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  • richardmitnick 12:04 pm on June 17, 2021 Permalink | Reply
    Tags: "10000 Years of Climate Memory Have Been Preserved in The Oldest Ice From The Alps", , Ca' Foscari University of Venice [Università Ca' Foscari Venezia] (IT), , , Paleogeology   

    From Ca’ Foscari University of Venice [Università Ca’ Foscari Venezia] (IT): “Ice Memory mission accomplished-10000 Years of Climate Memory Have Been Preserved in The Oldest Ice From The Alps” 

    From Ca’ Foscari University of Venice [Università Ca’ Foscari Venezia] (IT)

    10/06/2021
    Enrico Costa

    1
    The tent used for core sampling on Colle Gnifetti. On the ridge is Capanna Margherita, the highest mountain refuge in Europe.

    The Ice Memory mission on Monte Rosa has been accomplished. After working on the Gorner glacier for five days at 4,500m, scientists extracted two shallow core samples and two deep samples over 82m long.

    In the section closest to the rock, the sample could contain information on the climate and environment of ten thousand years ago. If analyses confirm this, it would mean that the most ancient ice in the Alps will be stored in Antarctica.

    2
    The last section of the first ice core (82.7m) is extracted.

    The mission was organised by the Institute of Polar Sciences (ISP) of the CNR Italian National Research Council [Consiglio Nazionale delle Ricerche] (IT) and Ca’ Foscari University of Venice, in collaboration with the SwissFEL | Paul Scherrer Institut (PSI) [freies Elektron ][électron libre] (CH).

    Ice Memory is an international programme that aims “to provide, now and for decades and centuries to come, the raw material and data necessary for scientific advances and political decisions that contribute to the sustainability and well-being of humanity”. It aims to do so by creating, in Antarctica, an archive of ice cores from the Earth’s mountain glaciers currently in danger of degradation or disappearance.

    “The mission was a success: the team obtained two ice cores over 80m deep from a very important site, which contains information on the climate of the last ten thousand years,” says Carlo Barbante, director of the CNR-ISP and professor at Ca’ Foscari. “The team worked well despite the harsh weather conditions, with strong gusts of wind and snow. Now this precious archive of the climate history of the Alps will be preserved for the future.”

    2
    The team at work during a blizzard.

    “Ice Memory is one of Ca’ Foscari’s most significant projects,” says Tiziana Lippiello, Rector of Ca’ Foscari. “Our university was among the first to engage in the study of climate change and of its impact on various fields (economics, science, society, culture). Our climate is in a state of emergency. In order to face this crisis, we need to understand the causes and find possible solutions, so research and teaching are necessary. With the Ice Memory project, Ca’ Foscari is committed to making a relevant contribution, together with CNR and the other international partners.”

    The mission

    On 1 June, the team left Alagna Valsesia (Vercelli) at the foot of Monte Rosa. The researchers spent two days at Capanna Gnifetti refuge (3,600m), in order to acclimatise. Then they continued on to Colle Gnifetti to carry out deep core sampling.

    For the duration of the mission, the scientists stayed at Capanna Margherita – the highest mountain refuge in Europe, built on a rocky peak 128 years ago for the purpose of contributing to scientific research in the field of physiology and, more recently, of climatology and natural science. Thanks to the support of Rifugi Monterosa, Capanna Margherita was opened just to host the scientists. The refuge will open again during the second half of June to welcome mountaineers.

    The team included Margit Schwikowski (Psi), Theo Jenk (team leader, Psi), François Burgay (Psi), Jacopo Gabrieli (Cnr/Ca’ Foscari), Fabrizio de Blasi (Cnr/Ca’ Foscari), Andrea Spolaor (Cnr/Ca’ Foscari), Paolo Conz (mountain guide), Sabine Harbeke (ZHdK, PolARTS project), Riccardo Selvatico (videomaker).

    The expedition on Monte Rosa was funded by the Italian Ministry of Education, University and Research (with the special supplementary fund for research, FISR) and by the Paul Scherrer Institute.

    The mission was sponsored by AKU and Karpos and featured the collaboration of Comune di Alagna Valsesia, Alagna’s Mountain Guides, Rifugi Monterosa, Monterosa 2000 spa, Camp, AVIS, ARPA Piemonte, ARPA Valle d’Aosta, Comitato Glaciologico Italiano, Ente di gestione delle aree protette della Valle Sesia, Fondazione Montagna Sicura, the University of Turin, Einwohnergemeinde Zermatt, Sektion Naturgefahren Kanton Wallis.

    See the full article here.

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    Please help promote STEM in your local schools.

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    Ca’ Foscari University of Venice [Università Ca’ Foscari Venezia] (IT) is a public university in Venice, Italy; it is usually known simply as Università Ca’ Foscari. Since its foundation in 1868 it has been housed in the Venetian Gothic palace of Ca’ Foscari, from which it takes its name. The palace stands on the Grand Canal, between the Rialto and San Marco, in the sestiere of Dorsoduro.

    The institute became a university in 1968. It currently has eight departments and almost 21,000 students. It is one of the highest ranked universities in Italy, ranking 5th in 2017 out of 89 universities.

    The institution was founded as the Regia Scuola Superiore di Commercio (“royal high school of commerce”) by a Royal Decree dated 6 August 1868, and teaching commenced in December of the same year. The idea of establishing such a school had arisen after the annexation of the Veneto to the new Kingdom of Italy in 1866, and was promoted by three people in particular: the Jewish political economist Luigi Luzzatti, later Prime Minister of Italy; Edoardo Deodati, senator of the Kingdom of Italy and vice-president of the province of Venice; and the Sicilian political economist Francesco Ferrara, director of the school for its first thirty years.

    The school was the first institute of higher education in commerce in Italy, and was from the outset conceived as a national rather than a regional institution; it had a diplomatic arm to prepare commercial consular staff for overseas service, and was also a training college for secondary school teachers of commercial subjects. Foreign languages were taught from the start. The school was modelled on the Institut Supérieur de Commerce d’Anvers, founded in 1853 in Antwerp, Belgium.

    Following the establishment of a national syllabus for university teaching in 1935, the Istituto Superiore di Economia e Commercio di Venezia, as it was by then called, was authorised to teach and award four-year laurea degrees. In 1968 it obtained university status, and the name was changed to Università degli Studi di Venezia. In the following year two new faculties were created, of industrial chemistry and of philosophy and letters.

    Currently, Ca’ Foscari hosts eight strategic research centers: the Center for Cultural Heritage and Technology, the Euro-Mediterranean Center on Climate Change, the European Centre for Living Technology, the Center for Humanities and Social Change, the Institute for Global Challenges, the Marco Polo Centre, the Venice Centre for Digital and Public Humanities, and the Venice Centre in Economic and Risk Analytics for Public Policies.

     
  • richardmitnick 4:36 pm on June 8, 2021 Permalink | Reply
    Tags: "Seafloor Seismometers Look for Clues to North Atlantic Volcanism", A new project called Structure Evolution and Seismicity of the Irish Offshore (SEA-SEIS)., An ongoing project is using seafloor seismometer data to investigate the origin of the lava eruptions., an upwelling of hot mantle rock originating from the core-mantle boundary that causes the tectonic plate in this region to flex upward., , Did the mantle plume that fuels Iceland’s volcanoes today cause eruptions in Ireland and Great Britain long ago?, , , Eruptions occurring 60 million years ago were not focused in the same area but rather were scattered across thousands of kilometers., , Giant’s Causeway in Northern Ireland formed as lava cooled slowly contracting and cracking in the process., Heated debates about the origins of North Atlantic volcanoes continue to stimulate multidisciplinary research and lead to a deeper understanding of mantle dynamics and its relationship to magmatism., North Atlantic Igneous Province (NAIP), Paleogeology, SEA-SEIS data should also inform understanding of the Iceland plume itself., SEA-SEIS has now delivered broadband seismic data from across a vast stretch of the North Atlantic seafloor., Seismologists from the Dublin Institute for Advanced Studies (DIAS) deployed 18 ocean bottom seismometers (OBSs) to the bottom of the northeastern Atlantic at depths of 1–4 kilometers., The breakup leading to the opening of the North Atlantic Ocean however was a complex multistage process., The Giants Causeway is only a small part of the Antrim Lava Group which comprises formations resulting from flood basalt eruptions in the Paleocene- about 60 million years ago., The thickness of Earth’s tectonic plates varies laterally and is typically between 60 and 300 kilometers., The volcanism and the abnormally shallow bathymetry of the northeastern Atlantic basin are thought to be caused by the Iceland plume, Today volcanic activity in the northeastern Atlantic continues through numerous volcanoes in Iceland., , We need data from seismic stations deployed on the North Atlantic seafloor—data that were not available until the SEA-SEIS project.   

    From Eos: Women in STEM-Maria Tsekhmistrenko “Seafloor Seismometers Look for Clues to North Atlantic Volcanism” 

    From AGU
    Eos news bloc

    From Eos

    6.8.21
    Sergei Lebedev
    sergei@cp.dias.ie

    Raffaele Bonadio

    Maria Tsekhmistrenko

    Janneke I. de Laat

    Christopher J. Bean

    Did the mantle plume that fuels Iceland’s volcanoes today cause eruptions in Ireland and Great Britain long ago? A new project investigates, while also inspiring students and recording whale songs.

    1
    Basalt columns at Giant’s Causeway in Northern Ireland formed as lava cooled slowly contracting and cracking in the process. An ongoing project is using seafloor seismometer data to investigate the origin of the lava erupted at this location and elsewhere around the North Atlantic Ocean. Credit: Sergei Lebedev/DIAS.

    The famous Giant’s Causeway on the coast of Northern Ireland comprises tens of thousands of spectacular basalt columns created as ancient lava flows slowly cooled and fractured into characteristic polygonal forms. Impressive in size though it is, the causeway is only a small part of the Antrim Lava Group, which comprises formations resulting from flood basalt eruptions that covered large areas with lava in the Paleocene, about 60 million years ago [Ganerød et al., 2010*].

    *See below for all references.

    At that time—just prior to continental separation and the onset of seafloor spreading in the northeastern Atlantic Ocean—these large eruptions were scattered across the entire region, forming the vast North Atlantic Igneous Province (NAIP). Remnants of these flood basalts are found on both sides of the Atlantic, from western Greenland and Baffin Island in the west to the northwestern European margin—including at Giant’s Causeway, Fingal’s Cave in Scotland, and elsewhere around Ireland and Great Britain—in the east [Peace et al., 2020*].

    Today volcanic activity in the northeastern Atlantic continues through numerous volcanoes in Iceland. This volcanism is unusual in that it occurs on a plate tectonic boundary—that separating the Eurasian and North American plates—but is not caused just by tectonic activity.

    3
    North American-Eurasian plate boundary.
    MARIO / Alamy Stock Photo [Used under “Fair Use” for academic teaching purpose with no monetary gain.]

    Instead, the volcanism and the abnormally shallow bathymetry of the northeastern Atlantic basin are thought to be caused by the Iceland plume, an upwelling of hot mantle rock originating from the core-mantle boundary that causes the tectonic plate in this region to flex upward [Morgan, 1971*].

    The formation of the NAIP has also been attributed to this plume [White and McKenzie, 1989*]. In contrast to recent eruptions, however, those occurring 60 million years ago were not focused in the same area but rather were scattered across thousands of kilometers. Explaining this broadly distributed volcanism, as well as many other outstanding questions about the dynamics and evolution of the Iceland plume and North Atlantic lithosphere, has long motivated scientific inquiry, but clear answers have been hard to come by because of gaps in seismic data coverage.

    Recently, researchers working on a new project called Structure Evolution and Seismicity of the Irish Offshore (SEA-SEIS), have collected data that will provide new insights into these old questions and that may finally tell us whether and how the Iceland plume could have caused havoc across the North Atlantic 60 million years ago [White and Lovell, 1997*].

    Hot Mantle, Heated Debates

    Hot plumes of rock that rise slowly from Earth’s core-mantle boundary to the surface are conventionally thought to be the cause of large igneous provinces, such as the NAIP, and of continental rifting and breakup [Morgan, 1971*]. The breakup leading to the opening of the North Atlantic Ocean however was a complex multistage process accompanied by compositionally variable and geographically scattered magmatic events—events that are far from fully understood [Peace et al., 2020*].

    Whereas some researchers have countered the plume model with alternatives that attempt to explain NAIP volcanism solely through lithospheric processes, others debate mechanisms by which magma from a relatively narrow mantle plume can be distributed over a much broader area of the surface. In particular, to what extent might topography at the base of the lithosphere have influenced the NAIP?

    The thickness of Earth’s tectonic plates varies laterally and is typically between 60 and 300 kilometers. Just as the topsides of these plates can have differing topography—shaped by tectonic forces, by volcanism, and by weathering and sedimentation processes at the planet’s surface—the undersides can as well, as a result of interactions between the lithosphere of the plates and the hotter, more ductile asthenosphere. This topography at the lithosphere-asthenosphere boundary (LAB) can include channels that guide lateral flows of buoyant material supplied by mantle plumes for many hundreds of kilometers. Such thin-lithosphere channels have been observed in seismic tomography models at the base of the currently active East Africa–Arabia volcanic region [Celli et al., 2020*]. They have also been detected beneath Greenland [Lebedev et al., 2018*], offering a potential explanation for Paleocene volcanism that occurred simultaneously along both its western and eastern coasts [Steinberger et al., 2019*].

    Could the topography of the LAB beneath the stretched continental lithosphere to the west and northwest of present-day Ireland—the westernmost portion of the Eurasian plate—have channeled hot material from the Iceland plume all the way to Ireland and Great Britain? If so, some of that topography might still be present today, as it is beneath Greenland, despite the continuing thermal evolution and reshaping of the LAB. Land-based seismic instruments do not offer the needed resolution to detect and map such features. Rather, we need data from seismic stations deployed on the North Atlantic seafloor—data that were not available until the SEA-SEIS project.

    Seismometers Dive Deep

    In September and October 2018, seismologists from the Dublin Institute for Advanced Studies (DIAS) in Ireland deployed 18 ocean bottom seismometers (OBSs) from the R/V Celtic Explorer, operated by Ireland’s Marine Institute, to the bottom of the northeastern Atlantic at depths of 1–4 kilometers (Figure 1). The network covered offshore waters south, west, and northwest of Ireland, as well as south of Iceland. The OBS units were NAMMUs, manufactured by Umwelt- und Meerestechnik Kiel (K.U.M.) in Germany, equipped with Trillium Compact 120-second broadband seismometers. They recorded three ground motion components and a broadband hydrophone channel, all at 250 samples per second.

    2
    Fig. 1. Locations of the 18 broadband, ocean bottom seismic stations (red circles) deployed by the SEA-SEIS project are shown on this map of the northeastern Atlantic region (left). Blue triangles show locations of broadband stations on land and wideband stations offshore from other permanent and temporary networks in the region. The SEA-SEIS stations were named by school students from across Ireland and in Italy (right).

    The station retrieval cruise took place from April to May 2020, at the height of the first wave of the COVID-19 pandemic, requiring organization and planning efforts by DIAS and the Marine Institute above and beyond those of typical research cruises. Each of the scientists involved self-isolated for 14 days prior to the survey before a private bus delivered them from their homes in Dublin to the ship in Galway. On board, each person had their own cabin and observed social distancing and other measures, like staggered mealtimes, for the duration of the cruise, which was completed without illness or other incident.

    Of the 14 instruments retrieved, one recorded data for 17 months, and the other 13 recorded for the full 19 months of the deployment, thanks to the batteries powering the instruments well past their 14-month nominal life span. Four of the instruments (Allód, Harry, Nemo, and Sebastian; see Figure 1) responded to communications from the ship but failed to detach from their anchors and, at the time of writing, remain on the seafloor. Recovery with a remotely operated underwater vehicle at a later date is now the most realistic—albeit challenging—option.

    3
    The deployment (top left, top right, and bottom left) and retrieval (bottom right) of ocean bottom seismometers are shown in this sequence. During deployment, the instrument is craned overboard and released into the water, where it descends to the seafloor. During retrieval, the instrument receives an acoustic command from the ship, detaches from its anchor, and slowly ascends (at roughly 1 meter per second) to the surface. The orange flag makes the seismometer easy to spot from the ship, and it is hooked and lifted onto the deck. Credit: Raffaele Bonadio, Janneke de Laat, and the SEA-SEIS team/DIAS.

    Earthquakes and Whale Songs

    SEA-SEIS has now delivered broadband seismic data from across a vast stretch of the North Atlantic seafloor. The new data will shed light on patterns and locations of offshore seismicity west of Ireland, which remains poorly understood but includes earthquakes larger than those occurring onshore Ireland. From preliminary analyses, the data indeed show clear recordings of both regional and teleseismic (distant) earthquakes; an example of one of these recordings is presented in the video clip below.


    A North Atlantic earthquake.

    These recordings will facilitate tomographic imaging and other seismic studies, which will yield new information about the lithospheric structure and evolution of the North Atlantic region. This information will reveal the structure and thickness of the lithosphere, which has been observed to be generally colder and thicker in the eastern compared with the western half of the northeastern Atlantic basin [Celli et al., 2021*]. We will use the new imaging to search for thin-lithosphere channels connecting Iceland with volcanic areas in and around Ireland and Great Britain.

    SEA-SEIS data should also inform understanding of the Iceland plume itself. Many whole-mantle tomography models show a major low-seismic velocity anomaly, interpreted as the Iceland plume, in the shallow lower mantle (below 660-kilometer depth) to the southeast of Iceland [Bijwaard and Spakman, 1999*]. Recent waveform tomography, by contrast, showed a tilted low-velocity anomaly rising toward Iceland from the northwest, beneath eastern Greenland [Celli et al., 2021*]. The new data will fill the large existing sampling gap and help us to reconcile these and other puzzling and seemingly contradictory observations.

    Beyond revealing new information about regional seismic activity, lithospheric structure, and volcanism past and present, SEA-SEIS data will aid other investigations as well. Recordings of the ambient noise between earthquakes, created as the ocean interacts with the seafloor and the continental shelf, will be analyzed to study noise generation and propagation in the North Atlantic [Le Pape et al., 2021*]. The SEA-SEIS data set also presents 19 months of continuous recordings of baleen whale vocalizations (a sample of which is given in the video clip below) collected across an area spanning more than half the width of the northeastern Atlantic Ocean.


    Fin whale song, offshore Ireland.

    The frequency band of the seismic and hydrophone data—determined at the high-frequency limit by the 250-per-second sampling rate—is sufficient to capture the ranges of blue and fin whale vocalizations, as well as the low-frequency parts of the ranges of humpbacks and North Atlantic right whales. The SEA-SEIS data set will be used to map the acoustic environment of these great whales, to detect and track them, and to study their migration patterns.

    4
    When the R/V Celtic Explorer retrieved OBS Charles, an octopus that had attached itself to the buoyant orange foam shell hitched a ride to the surface from the seafloor 1,127 meters below. The pressure tube holding the seismometer and data logger is visible at left. Credit: Sergei Lebedev and the SEA-SEIS team/DIAS.

    We were reminded often of the close presence of whales and other sea life while at sea. Fin whales that passed by were easily spotted by their tall columnar blows. Large groups of pilot whales surrounded the ship when we stopped and communicated with OBSs via an overboard transducer. They seemed curious about these acoustic communications, which are low amplitude by design, and the transducer picked up their constant squeaky chatter. When we lifted the seismometers onto the deck, we found that the ones from greater depths had been populated by hydroids, mollusks, and sponges. The two seismometers retrieved from depths of less than 1,200 meters each carried three octopuses guarding eggs laid on the devices.

    The mix of seismic, biological, and human signals in the SEA-SEIS data is awe-inspiring. When the signals are transformed into frequencies audible by the human ear, they give the listener the powerful experience of perceiving Earth and the ocean directly. Listen, for example, to the sample in the video below produced by the Sounds of the Earth project using recordings collected from the “Brian” OBS.


    Sounds of the Earth – Microseisms with passing ships and whales.

    A Clearer View Below the Seafloor

    Heated debates about the origins of North Atlantic volcanoes continue to stimulate multidisciplinary research and lead to a deeper understanding of mantle dynamics and its relationship to magmatism. Uncertainty has persisted, however, because of a vast gap in data sampling related to the lack of seismometers on the North Atlantic seafloor. The SEA-SEIS seismic stations fill a big part of this gap, allowing us to see deep below the North Atlantic seafloor and address long-standing and fundamental questions.

    These data should help reveal the deep structure of the Iceland plume, past and current dynamics of the North Atlantic lithosphere, and interactions between the two—all with greatly improved clarity. As for Giant’s Causeway, we plan to find out whether its distinctive columns really do share the same deep-mantle origins as the volcanoes now active in Iceland.

    Acknowledgments

    The OBSs and logistical support were provided by the Insitu Marine Laboratory for Geosystems Research (iMARL). We are grateful to Capt. Denis Rowan and the crew of the R/V Celtic Explorer and to R/V manager Aodhán Fitzgerald, Rosemarie Butler, and others at the Marine Institute for their expert assistance in collecting these unique data. The OBSs were NAMMU models, manufactured by K.U.M. in Germany. The data, now undergoing extensive preprocessing, quality control, and preparation for use in research, will be made openly available after the end of the project, scheduled for 2024. SEA-SEIS is cofunded by Science Foundation Ireland, the Geological Survey of Ireland, and the Marine Institute (grant 16/IA/4598). SEA-SEIS would not be possible without the dedication and hard work of everybody on the SEA-SEIS team.

    References:

    Bijwaard, H., and W. Spakman (1999), Tomographic evidence for a narrow whole mantle plume below Iceland, Earth Planet. Sci. Lett., 166, 121–126, https://doi.org/10.1016/S0012-821X(99)00004-7.

    Celli, N. L., et al. (2020), African cratonic lithosphere carved by mantle plumes, Nat. Commun., 11, 92, https://doi.org/10.1038/s41467-019-13871-2.

    Celli, N. L., et al. (2021), The tilted Iceland plume and its effect on the North Atlantic evolution and magmatism, Earth Planet. Sci. Lett., in press.

    Ganerød, M., et al. (2010), The North Atlantic Igneous Province reconstructed and its relation to the Plume Generation Zone: The Antrim Lava Group revisited, Geophys. J. Int., 182(1), 183–202, https://doi.org/10.1111/j.1365-246X.2010.04620.x.

    Lebedev, S., et al. (2018), Seismic tomography of the Arctic region: Inferences for the thermal structure and evolution of the lithosphere, in Circum-Arctic Lithosphere Evolution, edited by V. Pease and B. Coakley, Geol. Soc. Spec. Publ., 460, 419–440, https://doi.org/10.1144/SP460.10.

    Lebedev, S., et al. (2019), Education and public engagement using an active research project: Lessons and recipes from the SEA-SEIS North Atlantic Expedition’s programme for Irish schools, Geosci. Commun., 2, 143–155, https://doi.org/10.5194/gc-2-143-2019.

    Le Pape, F., D. Craig, and C. J. Bean (2021), How deep ocean–land coupling controls the generation of secondary microseism Love waves, Nat. Commun., 12, 2332, https://doi.org/10.1038/s41467-021-22591-5.

    Morgan, W. J. (1971), Convection plumes in the lower mantle, Nature, 230, 42–43, https://doi.org/10.1038/230042a0.

    Peace, A. L., et al. (2020), A review of Pangaea dispersal and large igneous provinces: In search of a causative mechanism, Earth Sci. Rev., 206, 102902, https://doi.org/10.1016/j.earscirev.2019.102902.

    Steinberger, B., et al. (2019), Widespread volcanism in the Greenland–North Atlantic region explained by the Iceland plume, Nat. Geosci., 12, 61–68, https://doi.org/10.1038/s41561-018-0251-0.

    White, N., and B. Lovell (1997), Measuring the pulse of a plume with the sedimentary record, Nature, 387, 888–891, https://doi.org/10.1038/43151.

    White, R., and D. McKenzie (1989), Magmatism at rift zones: The generation of volcanic continental margins and flood basalts, J. Geophys. Res., 94(B6), 7,685–7,729, https://doi.org/10.1029/JB094iB06p07685.

    Author Information

    Sergei Lebedev (sergei@cp.dias.ie), Raffaele Bonadio, Maria Tsekhmistrenko, Janneke I. de Laat, and Christopher J. Bean, Dublin Institute for Advanced Studies (IE), Ireland.

    See the full article here .

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  • richardmitnick 3:53 pm on May 16, 2021 Permalink | Reply
    Tags: "Earth’s Oldest Minerals Date Onset of Plate Tectonics to 3.6 Billion Years Ago", , , , High-aluminum zircons can only be produced in a limited number of ways which allows researchers to use the presence of aluminum to infer what may have been going on., Paleogeology, , Plate tectonics emerged roughly 3.6 billion years ago., Prior research on the 4 billion-year-old Acasta Gneiss in northern Canada also suggests that Earth’s crust was thickening and causing rock to melt deeper within the planet., Reconstructing how the Earth changed from a molten ball of rock and metal to what we have today., , The aluminum content of each zircon was also of interest to the research team., The oldest of the zircons in the study which came from the Jack Hills of Western Australia were around 4.3 billion years old., The results from the Acasta Gneiss give scientists more confidence in our interpretation of the Jack Hills zircons., The scientists deciphered a marked increase in aluminum concentrations roughly 3.6 billion years ago., The study uses zircons-the oldest minerals ever found on Earth-to peer back into the planet’s ancient past., These minerals provide the closest thing researchers have to a continuous chemical record of the nascent world., These nearly indestructible minerals formed when the Earth itself was in its infancy-only roughly 200 million years old., This work is part of the museum’s new initiative called Our Unique Planet.   

    From smithsonian.com “Earth’s Oldest Minerals Date Onset of Plate Tectonics to 3.6 Billion Years Ago” 

    smithsonian

    From smithsonian.com

    May 14, 2021

    Media Only
    Ryan Lavery
    (202) 633-0826
    laveryr@si.edu

    Randall Kremer
    (202) 633-0817
    kremerr@si.edu

    Press Office
    Media only
    Phone: (202) 633-2950
    Fax: (202) 786-2982

    Ancient Zircons From the Jack Hills of Western Australia Hone Date of an Event That Was Crucial To Making the Planet Hospitable to Life.

    1
    Credit: Michael Ackerson, Smithsonian.

    Scientists led by Michael Ackerson, a research geologist at the Smithsonian’s National Museum of Natural History, provide new evidence that modern plate tectonics, a defining feature of Earth and its unique ability to support life, emerged roughly 3.6 billion years ago.

    Earth is the only planet known to host complex life and that ability is partly predicated on another feature that makes the planet unique: plate tectonics. No other planetary bodies known to science have Earth’s dynamic crust, which is split into continental plates that move, fracture and collide with each other over eons. Plate tectonics afford a connection between the chemical reactor of Earth’s interior and its surface that has engineered the habitable planet people enjoy today, from the oxygen in the atmosphere to the concentrations of climate-regulating carbon dioxide. But when and how plate tectonics got started has remained mysterious, buried beneath billions of years of geologic time.

    The study, published May 14 in the journal Geochemical Perspective Letters, uses zircons-the oldest minerals ever found on Earth-to peer back into the planet’s ancient past.

    The oldest of the zircons in the study which came from the Jack Hills of Western Australia were around 4.3 billion years old—which means these nearly indestructible minerals formed when the Earth itself was in its infancy-only roughly 200 million years old. Along with other ancient zircons collected from the Jack Hills spanning Earth’s earliest history up to 3 billion years ago, these minerals provide the closest thing researchers have to a continuous chemical record of the nascent world.

    “We are reconstructing how the Earth changed from a molten ball of rock and metal to what we have today,” Ackerson said. “None of the other planets have continents or liquid oceans or life. In a way, we are trying to answer the question of why Earth is unique, and we can answer that to an extent with these zircons.”

    To look billions of years into Earth’s past, Ackerson and the research team collected 15 grapefruit-sized rocks from the Jack Hills and reduced them into their smallest constituent parts—minerals—by grinding them into sand with a machine called a chipmunk. Fortunately, zircons are very dense, which makes them relatively easy to separate from the rest of the sand using a technique similar to gold panning.

    The team tested more than 3,500 zircons, each just a couple of human hairs wide, by blasting them with a laser and then measuring their chemical composition with a mass spectrometer. These tests revealed the age and underlying chemistry of each zircon. Of the thousands tested, about 200 were fit for study due to the ravages of the billions of years these minerals endured since their creation.

    “Unlocking the secrets held within these minerals is no easy task,” Ackerson said. “We analyzed thousands of these crystals to come up with a handful of useful data points, but each sample has the potential to tell us something completely new and reshape how we understand the origins of our planet.”

    A zircon’s age can be determined with a high degree of precision because each one contains uranium. Uranium’s famously radioactive nature and well-quantified rate of decay allow scientists to reverse engineer how long the mineral has existed.

    The aluminum content of each zircon was also of interest to the research team. Tests on modern zircons show that high-aluminum zircons can only be produced in a limited number of ways which allows researchers to use the presence of aluminum to infer what may have been going on, geologically speaking, at the time the zircon formed.

    After analyzing the results of the hundreds of useful zircons from among the thousands tested, Ackerson and his co-authors deciphered a marked increase in aluminum concentrations roughly 3.6 billion years ago.

    “This compositional shift likely marks the onset of modern-style plate tectonics and potentially could signal the emergence of life on Earth,” Ackerson said. “But we will need to do a lot more research to determine this geologic shift’s connections to the origins of life.”

    The line of inference that links high-aluminum zircons to the onset of a dynamic crust with plate tectonics goes like this: one of the few ways for high-aluminum zircons to form is by melting rocks deeper beneath Earth’s surface.

    “It’s really hard to get aluminum into zircons because of their chemical bonds,” Ackerson said. “You need to have pretty extreme geologic conditions.”

    Ackerson reasons that this sign that rocks were being melted deeper beneath Earth’s surface meant the planet’s crust was getting thicker and beginning to cool, and that this thickening of Earth’s crust was a sign that the transition to modern plate tectonics was underway.

    Prior research on the 4 billion-year-old Acasta Gneiss in northern Canada also suggests that Earth’s crust was thickening and causing rock to melt deeper within the planet.

    “The results from the Acasta Gneiss give us more confidence in our interpretation of the Jack Hills zircons,” Ackerson said. “Today these locations are separated by thousands of miles, but they’re telling us a pretty consistent story, which is that around 3.6 billion years ago something globally significant was happening.”

    This work is part of the museum’s new initiative called Our Unique Planet, a public–private partnership, which supports research into some of the most enduring and significant questions about what makes Earth special. Other research will investigate the source of Earth’s liquid oceans and how minerals may have helped spark life.

    Ackerson said he hopes to follow up these results by searching the ancient Jack Hills zircons for traces of life and by looking at other supremely old rock formations to see if they too show signs of Earth’s crust thickening around 3.6 billion years ago.

    Funding and support for this research were provided by the Smithsonian and the National Aeronautics and Space Administration (NASA).

    See the full article here .

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    Smithsonian magazine and smithsonian.com place a Smithsonian lens on the world, looking at the topics and subject matters researched, studied and exhibited by the Smithsonian Institution — science, history, art, popular culture and innovation — and chronicling them every day for our diverse readership.

    The Smithsonian Institution (US) is a trust instrumentality of the United States composed as a group of museums and research centers. It was founded on August 10, 1846, “for the increase and diffusion of knowledge”. The institution is named after its founding donor, British scientist James Smithson. It was originally organized as the “United States National Museum”, but that name ceased to exist as an administrative entity in 1967.

    Termed “the nation’s attic” for its eclectic holdings of 154 million items, the Institution’s 19 museums, 21 libraries, nine research centers, and zoo include historical and architectural landmarks, mostly located in the District of Columbia. Additional facilities are located in Maryland, New York, and Virginia. More than 200 institutions and museums in 45 states, Puerto Rico, and Panama are Smithsonian Affiliates.

    The Institution’s 30 million annual visitors are admitted without charge. Its annual budget is around $1.2 billion, with two-thirds coming from annual federal appropriations. Other funding comes from the Institution’s endowment, private and corporate contributions, membership dues, and earned retail, concession, and licensing revenue. Institution publications include Smithsonian and Air & Space magazines.

    Research centers and programs

    The following is a list of Smithsonian research centers, with their affiliated museum in parentheses:

    Archives of American Art
    California State Railroad Museum
    Carrie Bow Marine Field Station (Natural History Museum)
    Center for Earth and Planetary Studies (Air and Space Museum)
    Center for Folklife and Cultural Heritage
    Marine Station at Fort Pierce (Natural History Museum)
    Smithsonian Migratory Bird Center (National Zoo)
    Museum Conservation Institute
    Smithsonian Asian Pacific American Center
    Smithsonian Astrophysical Observatory and the associated Harvard–Smithsonian Center for Astrophysics
    Smithsonian Conservation Biology Institute (National Zoo)
    Smithsonian Environmental Research Center
    Smithsonian Institution Archives
    Smithsonian Libraries
    Smithsonian Institution Scholarly Press
    Smithsonian Latino Center
    Smithsonian Provenance Research Initiative (SPRI)
    Smithsonian Science Education Center
    Smithsonian Tropical Research Institute (Panamá)
    Woodrow Wilson International Center for Scholars

    Also of note is the Smithsonian Museum Support Center (MSC), located in Silver Hill, Maryland (Suitland), which is the principal off-site conservation and collections facility for multiple Smithsonian museums, primarily the National Museum of Natural History. The MSC was dedicated in May 1983. The MSC covers 4.5 acres (1.8 ha) of land, with over 500,000 square feet (46,000 m^2) of space, making it one of the largest set of structures in the Smithsonian. It has over 12 miles (19 km) of cabinets, and more than 31 million objects.

     
  • richardmitnick 7:14 pm on April 5, 2021 Permalink | Reply
    Tags: "First continents formed with a dash of mantle water", , , , , , Paleogeology   

    From Curtin University (AU) via COSMOS (AU): “First continents formed with a dash of mantle water” 

    From Curtin University (AU)

    via

    Cosmos Magazine bloc

    COSMOS (AU)

    5 April 2021

    Chris Kirkland, Curtin University
    Hugh Smithies, Curtin University
    Tim Johnson, Curtin University

    1
    Karijini National Park, in the Pilbara region of Western Australia. Credit: TED MEAD / Getty Images.

    Earth is an amazing planet. As far as we know, it’s the only planet in the universe where life exists. It’s also the only planet known to have continents: the land masses on which we live and which host the minerals needed to support our complex lives.

    Experts still vigorously debate how the continents formed. We do know water was an essential ingredient for this — and many geologists have proposed this water would have come from Earth’s surface via subduction zones (as is the case now).

    But our new research [Nature] shows this water would have actually come from deep within the planet. This suggests Earth in its youth behaved very differently to how it does today, containing more primordial water than previously thought.

    How to grow a continent

    The solid Earth is comprised of a series of layers including a dense iron-rich core, thick mantle and a rocky outer layer called the lithosphere.

    But it wasn’t always this way. When Earth first formed about 4.5 billion years ago, it was a ball of molten rock that was regularly pummelled by meteorites.

    As it cooled over a period of a billion years or so, the first continents began to emerge, made of pale-coloured granite. Exactly how they came to be has long intrigued scientists.

    2
    Earth comprises a core, mantle and outer crust. Credit: Shutterstock.

    To make granitic continental crust capable of floating, dark volcanic rocks known as basalts have to be melted. Basalts, which are formed as a result of melting in the mantle, would have covered Earth when the planet was starting out.

    However, to make continental crust from basalt requires another essential ingredient: water. Knowing how this water got into the rocks at enough depth is key to understanding how the first continents formed.

    One mechanism of taking water to depth is through subduction. This is how most new continental crust is produced today, including the Andes mountain range in South America.

    In subduction zones, rocky plates at the bottom of the ocean chill and become increasingly dense until they’re forced under the continents and back into the mantle below, taking ocean water with them.

    When this water interacts with basalt in the mantle, it creates granitic crust. But Earth was much hotter billions of years ago, so many experts have argued subduction (at least in the form we currently understand) couldn’t have operated [Nature].

    Long linear mountain belts such as the Andes contrast starkly with the structure of the granitic crust preserved in the Pilbara region of outback Western Australia.

    This ancient crust viewed from above has a “dome-and-keel” pattern, with balloons (domes) of pale-coloured granite rising into the surrounding darker and denser basalts (the keels).

    2
    Satellite images of the Pilbara Craton, Western Australia. Pale-coloured granite domes are surrounded by dark-coloured basalts. Credit: Google Earth.

    But where did the water needed to produce these domes come from?

    Tiny crystals record Earth’s early history

    Our research, led by scientists at the Geological Survey of Western Australia and Curtin University, addressed this question. We analysed tiny crystals trapped in the ancient magmas that cooled and solidified to form the Pilbara’s granite domes.

    These crystals, made of a mineral called zircon, contain uranium which turns into lead over time. We know the rate of this change, and can measure the amounts of uranium and lead contained within. As such, we can obtain a record of their age.

    3
    Zircon crystals grown in an ancient magma.

    The crystals also contain clues to their origin, which can be unravelled by measuring their oxygen isotope composition. Importantly, zircons that crystallised in molten rocks hydrated by water from Earth’s surface have different compositions to zircons that formed deep in the mantle.

    Measurements show the water required for the most primitive ancient WA granites would have come from deep within Earth’s mantle and not from the surface.

    4
    Chris Kirkland (left) and Tim Johnson loading samples into a secondary-ion mass spectrometer, which shoots a beam of ions into zircon crystals to determine their age and oxygen isotope composition.

    Is the present always the key to the past?

    How the first continents formed is part of a broader debate regarding one of the central tenets of the physical sciences: uniformitarianism. This is the idea that the processes which operated on Earth in the distant past are the same as those observed today.

    Earth today loses heat through plate tectonics, when the ridged lithospheric plates that form the planet’s solid, outer shell move around. This helps regulate its internal temperature, stabilises atmospheric composition, and probably also facilitated the development of complex life.

    Subduction is one of the most important components of this process. But several lines of evidence [Terra Nova] are inconsistent with subduction and plate tectonics on an early Earth. They indicate strongly that our planet behaved very differently in the first two billion years following its formation than it does today.

    So while uniformitarianism is a useful way to think about many geological processes, the present may not always be the key to the past.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Curtin University (AU) (formerly known as Curtin University of Technology and Western Australian Institute of Technology) is an Australian public research university based in Bentley and Perth, Western Australia. The university is named after the 14th Prime Minister of Australia, John Curtin, and is the largest university in Western Australia, with over 58,000 students (as of 2016).

    Curtin would like to pay respect to the indigenous members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Wadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.

    Curtin was conferred university status after legislation was passed by the Parliament of Western Australia in 1986. Since then, the university has been expanding its presence and has campuses in Singapore, Malaysia, Dubai and Mauritius. It has ties with 90 exchange universities in 20 countries. The University comprises five main faculties with over 95 specialists centres. The University formerly had a Sydney campus between 2005 & 2016. On 17 September 2015, Curtin University Council made a decision to close its Sydney campus by early 2017.

    Curtin University is a member of Australian Technology Network (ATN), and is active in research in a range of academic and practical fields, including Resources and Energy (e.g., petroleum gas), Information and Communication, Health, Ageing and Well-being (Public Health), Communities and Changing Environments, Growth and Prosperity and Creative Writing.

    It is the only Western Australian university to produce a PhD recipient of the AINSE gold medal, which is the highest recognition for PhD-level research excellence in Australia and New Zealand.

    Curtin has become active in research and partnerships overseas, particularly in mainland China. It is involved in a number of business, management, and research projects, particularly in supercomputing, where the university participates in a tri-continental array with nodes in Perth, Beijing, and Edinburgh. Western Australia has become an important exporter of minerals, petroleum and natural gas. The Chinese Premier Wen Jiabao visited the Woodside-funded hydrocarbon research facility during his visit to Australia in 2005.

     
  • richardmitnick 4:17 pm on April 5, 2021 Permalink | Reply
    Tags: "Probing the Age of the Oldest Ocean Crust in the Pacific", , , , , Paleogeology, The current GPTS extends from today backward in time down to magnetic anomaly M29 (approximately 157 million years ago)., The geomagnetic polarity time scale (GPTS) is based on the marine magnetic anomalies- the striping pattern of strong and weak magnetic signals recorded by the ocean crust., Tominaga et al. [2021] extend the geomagnetic polarity time scale down to the Mid Jurassic (M44- about 170 million years ago) based on a composite of the Japanese lineation set they published previous   

    From Eos: “Probing the Age of the Oldest Ocean Crust in the Pacific” 

    From AGU
    Eos news bloc

    From Eos

    4.5.21
    Mark J. Dekkers

    1
    Map of magnetic anomaly field intensity in the study area in the Pacific Ocean, with the location of the magnetic anomaly profiles indicated with green lines. Blue colors indicate a positive polarity (normal field) and red colors negative polarity (reverse field); pale (intense) colors indicate weak (strong) magnetic anomaly expression. Credit: Tominaga et al. [2021] [below], Figure 8b.

    The geomagnetic polarity time scale (GPTS) is based on the marine magnetic anomalies- the striping pattern of strong and weak magnetic signals recorded by the ocean crust. Strong signals correspond to normal polarity and weak signals to reverse polarity. Adjacent normal and reverse stripes are numbered, backward in time from C1 (top = today) to C34, of which the normal portion is a long period of normal polarity in the Mid Cretaceous. Older magnetic stripes are referred to as the M-sequence (Mesozoic sequence) starting with M0 below the very long C34 anomaly.

    The current GPTS extends from today backward in time down to magnetic anomaly M29 (approximately 157 million years ago). Older oceanic crust is rare and typically has subdued magnetic anomaly patterns that are difficult to correlate. Thus, pre-M29 time scales remain controversial because the marine magnetic anomaly data is of rather poor quality. This complicates analysis of important features of the geomagnetic field: the reversal frequency and the expression of the Mesozoic dipole low (also termed Jurassic Quiet Zone).

    Tominaga et al. [2021] extend the geomagnetic polarity time scale down to the Mid Jurassic (M44- about 170 million years ago) based on a composite of the Japanese lineation set they published previously, and a new, highly detailed, multiscale magnetic anomaly profile of the Hawaiian lineation set, both from the western Pacific Ocean.

    The weak anomaly portion M41-M39 is best expressed in the Japanese profile and argued to represent the onset and maximum expression of the Mesozoic dipole low or the core of the Jurassic Quiet Zone, an important long-lasting low-intensity feature of the geomagnetic field. From the midwater reference profile, the Jurassic reversal frequency in the M29-M44 time span (157-170 million years ago) appears to have been about 19 reversals per million years, i.e. extraordinarily high, and double the previous estimates for that period.

    Citation: Tominaga, M., Tivey, M. A., & Sager, W. W. [2021] Journal of Geophysical Research: Solid Earth.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 2:28 pm on March 25, 2021 Permalink | Reply
    Tags: "Curtin research finds first clues to start of Earth’s supercontinent cycle", , , , , Paleogeology,   

    From Curtin University (AU): “Curtin research finds first clues to start of Earth’s supercontinent cycle” 

    From Curtin University (AU)

    24 March 2021

    Greta Carlshausen
    Media Officer
    Tel: +61 8 9266 3549
    Mob: +61 422 993 535
    greta.carlshausen@curtin.edu.au

    Vanessa Beasley
    Deputy Director
    Tel: +61 8 9266 1811
    Mob: +61 466 853 121
    vanessa.beasley@curtin.edu.au

    Curtin University research has uncovered the first solid clues about the very beginning of the supercontinent cycle of Earth, finding it was kick-started two billion years ago.

    1
    The Blue Marble.

    Detailed in a paper published in Geology, a team of researchers from Curtin’s Earth Dynamics Research Group found that plate tectonics operated differently before two billion years ago, and the 600 million years supercontinent cycle likely only started during the second half of Earth’s life.

    Lead researcher Dr Yebo Liu from Curtin’s School of Earth and Planetary Sciences said that the shift in plate tectonics marked a regime change in the Earth System.

    “This regime change impacted on the eventual emergence of complex life and even how Earth resources are formed and preserved,” Dr Liu said.

    “Pangea was the first supercontinent scientists discovered early last century that existed some 300 million years ago and lasted until the age of the dinosaurs.

    3
    Map of Pangaea 200 million years ago. Mollweide projection centred on 0°,0°. Made using GPlates and data sets listed below:

    Amante, C. and Eakins, B. W. 2009. ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and Analysis. NOAA Technical Memorandum NESDIS NGDC-24, 19.
    Matthews, K.J., Maloney, K.T., Zahirovic, S., Williams, S.E., Seton, M., and Müller, R.D. (2016). Global plate boundary evolution and kinematics since the late Paleozoic, Global and Planetary Change, 146, 226-250. DOI: 10.1016/j.gloplacha.2016.10.002
    Müller, R.D., Seton, M., Zahirovic, S., Williams, S.E., Matthews, K.J., Wright, N.M., Shephard, G.E., Maloney, K.T., Barnett-Moore, N., Hosseinpour, M., Bower, D.J. & Cannon, J. 2016. Ocean Basin Evolution and Global-Scale Plate Reorganization Events Since Pangea Breakup, Annual Review of Earth and Planetary Sciences, vol. 44, pp. 107 . DOI: 10.1146/annurev-earth-060115-012211.
    Credit: Fama Clamosa

    Geologists realised more recently that at least two older supercontinents existed before Pangea in the past two billion years (Ga) in a 600 million year cycle. But what happened in the first 2.5 billion years of Earth’s history is anybody’s guess.”

    “Our research was essentially testing two hypotheses – one is that the supercontinent cycle started prior to two billion years ago. Alternatively, the ancient continents (called cratons) only managed to get together in multiple clusters called supercratons, instead of forming a singular supercontinent.”

    To conduct their tests, the Curtin researchers ventured into the hills east of Perth, Western Australia, an area known as the Yilgarn craton.

    Dr Liu said Yilgarn was a critical piece of the puzzle not only because it is old, but also because there are a series of dark rocks or dolerite dykes that recorded Earth’s ancient magnetic field at the time that the rocks formed.

    “By precisely dating the rocks and measuring the samples’ magnetic record, using a technique called palaeomagnetism, we are able to reconstruct where those rocks were (relative to the magnetic North pole) when they formed,” Dr Liu said.

    Co-author John Curtin Distinguished Professor Zheng-Xiang Li, from Curtin’s School of Earth and Planetary Sciences, said by analysing their new data from Yilgarn, and comparing it with data available globally for other cratons, one thing became clear.

    “It was clear that we can almost rule out the existence of a long-lived single supercontinent before two billion years ago (2 Ga), although transient supercontinents may have existed” Professor Li said.

    “More likely, there could have been two long-lived clusters of cratons, or supercratons, before 2 Ga that were geographically isolated from each other, never forming a singular supercontinent.”

    Professor Ross Mitchell of the Chinese Academy of Sciences, who was previously a member of Curtin’s Earth Dynamics Research Group, said the research goes some way to solving a long-standing mystery.

    “The idea of an even older supercontinent has been speculated about for years. But while it has been difficult to prove, it has also been difficult to disprove,” Professor Mitchell said.

    Dr Liu said more studies now need to be done.

    “This study surely isn’t the final word on the debate, but it’s certainly a step in the right direction and we need to collect data from a lot more similar rocks to further test the hypotheses,” Dr Liu said.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Curtin University (AU) (formerly known as Curtin University of Technology and Western Australian Institute of Technology) is an Australian public research university based in Bentley and Perth, Western Australia. The university is named after the 14th Prime Minister of Australia, John Curtin, and is the largest university in Western Australia, with over 58,000 students (as of 2016).

    Curtin would like to pay respect to the indigenous members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Wadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.

    Curtin was conferred university status after legislation was passed by the Parliament of Western Australia in 1986. Since then, the university has been expanding its presence and has campuses in Singapore, Malaysia, Dubai and Mauritius. It has ties with 90 exchange universities in 20 countries. The University comprises five main faculties with over 95 specialists centres. The University formerly had a Sydney campus between 2005 & 2016. On 17 September 2015, Curtin University Council made a decision to close its Sydney campus by early 2017.

    Curtin University is a member of Australian Technology Network (ATN), and is active in research in a range of academic and practical fields, including Resources and Energy (e.g., petroleum gas), Information and Communication, Health, Ageing and Well-being (Public Health), Communities and Changing Environments, Growth and Prosperity and Creative Writing.

    It is the only Western Australian university to produce a PhD recipient of the AINSE gold medal, which is the highest recognition for PhD-level research excellence in Australia and New Zealand.

    Curtin has become active in research and partnerships overseas, particularly in mainland China. It is involved in a number of business, management, and research projects, particularly in supercomputing, where the university participates in a tri-continental array with nodes in Perth, Beijing, and Edinburgh. Western Australia has become an important exporter of minerals, petroleum and natural gas. The Chinese Premier Wen Jiabao visited the Woodside-funded hydrocarbon research facility during his visit to Australia in 2005.

     
  • richardmitnick 11:12 am on March 13, 2021 Permalink | Reply
    Tags: "Ancient Magma From Earth's Early Days Discovered in Rocks From Greenland", An analysis of rocks from a formation in Greenland reveals traces of a geological journey that took place at a time when our rocky world was little more than a molten ocean of magma., , Carleton University(CA), , , Paleogeology, Particular attention paid to signature levels of iron isotopes in a powdered sample of basalt taken from the northern parts of the Isua Greenland Belt (ISB)., ,   

    From University of Chicago(US) and Carleton University(CA) via Science Alert(AU): “Ancient Magma From Earth’s Early Days Discovered in Rocks From Greenland” 

    U Chicago bloc

    From University of Chicago(US)

    via

    ScienceAlert

    Science Alert(AU)

    12 MARCH 2021
    MIKE MCRAE

    1
    Isua Greenland Belt. Credit: Hanika Rizo.

    Our planet’s surface has seen a thing or two in its 4.5 billion-odd-years of existence. Weathered by ocean, corroded by wind, and remolded by the relentless turnover of plate tectonics, we might assume nothing remains of Earth in its most primitive state.

    Yet an analysis of rocks from a formation in Greenland reveals traces of a geological journey that took place at a time when our rocky world was little more than a molten ocean of magma, and it could fill in missing details on our ancient past.

    Researchers from the University of Cambridge(UK) and Carleton University(CA) paid particular attention to signature levels of iron isotopes in a powdered sample of basalt taken from the northern parts of the Isua Greenland Belt (ISB).

    Along with a study of its tungsten, the chemical signatures reflect the basalt’s birth from a mix of components from different parts of the mantle at a time when Earth’s entirely molten surface was hardening.

    The Isua belt is a strip of crust in Greenland’s southwest that has remained relatively unchanged for a mind-blowing 3.7 billion years, officially making them the oldest rocks on Earth.

    For more than half a century the ISB has been a regular haunt for planetary scientists and biologists keen to learn more about how our planet’s crust formed, and how its chemistry – including the earliest forms of life – might have emerged.

    As old as the belt might be, Earth had already been a planet of sorts for a good half a billion years prior to their formation. Not that we’d recognize it now.

    Heated by frequent collisions of new material raining down from space and radioactive materials that hadn’t yet sunk to the planet’s core, there was no crust yet as such – just a churning blob of mineral soup.

    We can work that much out by applying models of planetary formation, but many of the finer details of what went on below remain sketchy. What kinds of currents were rising and falling in our planet’s guts? How was energy transferred? What sorts of minerals might have crystallized out of solution as it cooled?

    These are questions that could be answered if we had pristine samples of that magma. Fortunately, that’s just what happens to be locked up in Isua.

    “There are few opportunities to get geological constraints on the events in the first billion years of Earth’s history,” says lead study author, Earth scientist Helen Williams from the University of Cambridge.

    “It’s astonishing that we can even hold these rocks in our hands – let alone get so much detail about the early history of our planet.”

    Previous research [Earth and Planetary Science Letters] on the sample’s recipe of hafnium and neodymium isotopes had already hinted at the rock’s origins spewing out of the planet’s mantle some 3.7 billion years ago, potentially preserving signatures of a time when the magma ocean was still crystallizing.

    Measuring a specific isotope of iron in the rock’s make-up cemented speculations that at least some of it had been flowing as a liquid just beneath ancient Earth’s first skin.

    Other measurements suggested there was more to the story, though, revealing a component made up of minerals that had risen from much deeper down.

    That deeper rock shows signs of spending time in the lower mantle, with evidence of being forged by dynamic processes that involved a cycle of melting and crystallization before being blended with material in the upper mantle.

    Fresh new volcanic rocks blasted onto the surface in other parts of the world today display similar signs of mixing, suggesting it’s possible ancient processes close to the planet’s core are still at work deep beneath our feet today.

    Tying together the evidence to show exactly how our adolescent Earth chilled out and crusted up will take a lot more evidence.

    Ancient records of Earth’s distant past will continue to erode away slowly. Fortunately we’re quickly learning how to unravel the clues they contain.

    “The evidence is often altered by the course of time,” says Williams.

    “But the fact we found what we did suggests that the chemistry of other ancient rocks may yield further insights into the Earth’s formation and evolution – and that’s immensely exciting.”

    This research was published in Science Advances.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: Argonne National Laboratory, Fermi National Accelerator Laboratory, and the Marine Biological Laboratory in Woods Hole, Massachusetts.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts. The University of Chicago is a private research university in Chicago, Illinois. Founded in 1890, its main campus is located in Chicago’s Hyde Park neighborhood. It enrolled 16,445 students in Fall 2019, including 6,286 undergraduates and 10,159 graduate students. The University of Chicago is ranked among the top universities in the world by major education publications, and it is among the most selective in the United States.

    The university is composed of one undergraduate college and five graduate research divisions, which contain all of the university’s graduate programs and interdisciplinary committees. Chicago has eight professional schools: the Law School, the Booth School of Business, the Pritzker School of Medicine, the School of Social Service Administration, the Harris School of Public Policy, the Divinity School, the Graham School of Continuing Liberal and Professional Studies, and the Pritzker School of Molecular Engineering. The university has additional campuses and centers in London, Paris, Beijing, Delhi, and Hong Kong, as well as in downtown Chicago.

    University of Chicago scholars have played a major role in the development of many academic disciplines, including economics, law, literary criticism, mathematics, religion, sociology, and the behavioralism school of political science, establishing the Chicago schools in various fields. Chicago’s Metallurgical Laboratory produced the world’s first man-made, self-sustaining nuclear reaction in Chicago Pile-1 beneath the viewing stands of the university’s Stagg Field. Advances in chemistry led to the “radiocarbon revolution” in the carbon-14 dating of ancient life and objects. The university research efforts include administration of DOE’s Fermi National Accelerator Laboratory(US) and DOE’s Argonne National Laboratory(US), as well as the U Chicago Marine Biological Laboratory in Woods Hole, Massachusetts (MBL)(US). The university is also home to the University of Chicago Press, the largest university press in the United States. The Barack Obama Presidential Center is expected to be housed at the university and will include both the Obama presidential library and offices of the Obama Foundation.

    The University of Chicago’s students, faculty, and staff have included 100 Nobel laureates as of 2020, giving it the fourth-most affiliated Nobel laureates of any university in the world. The university’s faculty members and alumni also include 10 Fields Medalists, 4 Turing Award winners, 52 MacArthur Fellows, 26 Marshall Scholars, 27 Pulitzer Prize winners, 20 National Humanities Medalists, 29 living billionaire graduates, and have won eight Olympic medals.

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics; establishing revolutionary theories of economics; and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts.

     
  • richardmitnick 9:48 pm on February 11, 2021 Permalink | Reply
    Tags: "Earth's mountains disappeared for a billion years and then life stopped evolving", , , , , , , , Paleogeology, Peking University [北京大学] (CN), , Studying ancient Earth's crustal thickness can be the best way to gauge how actively mountains formed in the past., The study authors analyzed the changing composition of zircon minerals that crystallized in the crust billions of years ago., The University of Science and Technology [中国科学技术大学] (CN),   

    From Peking University [北京大学] (CN), The University of Toronto (CA), Rutgers University (US) and The University of Science and Technology [中国科学技术大学] (CN) via Live Science: “Earth’s mountains disappeared for a billion years and then life stopped evolving” 

    From Live Science

    2.11.21
    Brandon Specktor

    A dead supercontinent may be to blame.

    1
    The supercontinent of Nuna-Rodinia broke up at the end of the Proterozoic era, ending a billion years of no new mountain formation, a new study says. © Fama Clamosa/ CC 4.0.

    A tetrad of researchers from Peking University [北京大学] (CN), the University of Toronto (CA), Rutgers University (US) and the University of Science and Technology [中国科学技术大学] (CN) has found evidence that suggests the Earth was mostly flat during its middle ages.

    2

    In their paper published in the journal Science, the group describes their study of europium embedded in zircon crystals and what it revealed about Earth’s ancient past.

    Earth, like so many of its human inhabitants, may have experienced a mid-life crisis that culminated in baldness. But it wasn’t a receding hairline our planet had to worry about; it was a receding skyline.

    For nearly a billion years during our planet’s “middle age” (1.8 billion to 0.8 billion years ago), Earth’s mountains literally stopped growing, while erosion wore down existing peaks to stumps, according to a study published Feb. 11 in the journal Science.

    This extreme mountain-forming hiatus — which resulted from a persistent thinning of Earth’s continental crust — coincided with a particularly bleak eon that geologist’s call the “boring billion,” the researchers wrote. Just as Earth’s mountains failed to grow, the simple life-forms in Earth’s oceans also failed to evolve (or at least, they evolved incredibly slowly) for a billion years.

    According to lead study author Ming Tang, the mountain of trouble on Earth’s continents may have been partially responsible for the slow going in Earth’s seas.

    “Continents were mountainless in the middle age,” Tang, an assistant professor at Peking University [北京大学] (CN) in Beijing, told Live Science in an email. “Flatter continents may have reduced nutrient supply [to the ocean] and hindered the emergence of complex life.”

    When mountains vanish

    At the convergent boundaries where Earth’s continental plates clash, mountains soar upward in a process called orogenesis.

    The tectonic plates of the world were mapped in 1996, USGS.

    The continental crust at these boundaries is thicker on average and buoyed by magma, lifting surface rocks up to dizzying heights. Meanwhile, erosion and gravity push back against the peaks; when the tectonic and magmatic processes below the surface stop, erosion wins out, whittling mountains away.

    Because even the mightiest mountains disappear over time, studying ancient Earth’s crustal thickness can be the best way to gauge how actively mountains formed in the past. To do that, the study authors analyzed the changing composition of zircon minerals that crystallized in the crust billions of years ago.

    Today, tiny grains of zircon are easily found in sedimentary rocks all over the planet’s surface. The precise elemental composition of each grain can reveal the conditions in the crust where those minerals first crystallized, eons ago.

    “Thicker crust forms higher mountains,” Tang said. Crustal thickness controls the pressure at which magma changes composition, which then gets recorded by anomalies in zircons crystallizing from that magma, he added.

    In a previous study published in January in the journal Geology, Tang and colleagues found that the amount of europium embedded in zircon crystals could reveal crust thickness at the time those crystals formed. More europium signifies higher pressure placed on the crystal, which signifies thicker crust above it, the researchers found.

    Now, in their new study in Science, the researchers analyzed zircon crystals from every content, and then used those europium anomalies to construct a history of continental thickness going back billions of years. They found that “the average thickness of active continental crust varied on billion-year timescales,” the researchers wrote, with the thickest crust forming in the Archaean eon (4 billion to 2.5 billion years ago) and the Phanerozoic (540 million years ago to the present).

    Right between those active mountain-forming eras, crustal thickness plummeted through the Proterozoic eon (2.5 billion to 0.5 billion years ago), reaching a low during Earth’s “middle age.”

    The eon of nothing

    It may not be a coincidence that Earth’s flattest eon on land was also its most “boring” eon at sea, Tang said.

    “It is widely recognized by our community that life evolution was extremely slow between 1.8-0.8 billion years ago,” Tang told Live Science. “Although eukaryotes emerged 1.7 billion years ago, they only rose to dominance some 0.8 billion years ago.”

    By contrast, Tang said, the Cambrian explosion, which occurred just 300 million years later, introduced almost all major animal groups that we see today. For whatever reason, life evolved achingly slowly during the “boring billion,” then jump-started just as the crust began thickening.

    What’s the correlation? If no new mountains formed during this period, then no new nutrients were introduced to Earth’s surface from the mantle below, the researchers wrote — and a dearth of nutrients on land also meant a dearth of nutrients making their way into the ocean through the water cycle. As mountain forming stalled for a billion years, a “famine” of phosphorus and other essential elements could have starved Earth’s simple sea critters, limited their productivity and stalled their evolution, the team suggests.

    Life, and mountains, eventually flourished again when the supercontinent Nuna-Rodinia broke apart at the end of the Proterozoic eon. But before then, this gargantuan continent may have been so massive that it effectively altered the structure of the mantle below, stalling plate tectonics during the “boring billion” and resulting in an eon of crustal thinning, the researchers wrote. But further research is needed to fully solve the mystery of Earth’s vanishing mountains.

    See the full article here .

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  • richardmitnick 10:38 am on February 8, 2021 Permalink | Reply
    Tags: "Geologists produce new timeline of Earth’s Paleozoic climate changes", , Carbonate muds, Clumped isotope geochemistry, , , , , Paleogeology, Paleozoic era, The temperature of a planet is linked with the diversity of life that it can support., Warmer climates favored microbial life whereas cooler temperatures allowed more diverse animals to flourish.   

    From MIT: “Geologists produce new timeline of Earth’s Paleozoic climate changes” 

    MIT News

    From MIT News

    February 1, 2021 [Just today in social media]
    Jennifer Chu

    1
    A small trilobite fossil from the Ordovician strata in Svalbard, Norway.
    Credit: Adam Jost

    The temperature of a planet is linked with the diversity of life that it can support. MIT geologists have now reconstructed a timeline of the Earth’s temperature during the early Paleozoic era, between 510 and 440 million years ago — a pivotal period when animals became abundant in a previously microbe-dominated world.

    In a study appearing today in the PNAS, the researchers chart dips and peaks in the global temperature during the early Paleozoic. They report that these temperature variations coincide with the planet’s changing diversity of life: Warmer climates favored microbial life, whereas cooler temperatures allowed more diverse animals to flourish.

    The new record, more detailed than previous timelines of this period, is based on the team’s analysis of carbonate muds — a common type of limestone that forms from carbonate-rich sediments deposited on the seafloor and compacted over hundreds of millions of years.

    “Now that we have shown you can use these carbonate muds as climate records, that opens the door to looking back at this whole other part of Earth’s history where there are no fossils, when people don’t really know much about what the climate was,” says lead author Sam Goldberg, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).

    Goldberg’s co-authors are Kristin Bergmann, the D. Reid Weedon, Jr. Career Development Professor in EAPS, along with Theodore Present of Caltech and Seth Finnegan of the University of California at Berkeley.

    Beyond fossils

    To estimate Earth’s temperature many millions of years ago, scientists analyze fossils, in particular, remains of ancient shelled organisms that precipitated from seawater and either grew on or sank to the seafloor. When precipitation occurs, the temperature of the surrounding water can change the composition of the shells, altering the relative abundances of two isotopes of oxygen: oxygen-16, and oxygen-18.

    “As an example, if carbonate precipitates at 4 degrees Celsius, more oxygen-18 ends up in the mineral, from the same starting composition of water, [compared to] carbonate precipitating at 30 degrees Celsius,” Bergmann explains. “So, the ratio of oxygen-18 to -16 increases as temperature cools.”

    In this way, scientists have used ancient carbonate shells to backtrack the temperature of the surrounding seawater — an indicator of the Earth’s overall climate — at the time the shells first precipitated. But this approach has taken scientists only so far, up until the earliest fossils.

    “There is about 4 billion years of Earth history where there were no shells, and so shells only give us the last chapter,” Goldberg says.

    A clumped isotope signal

    The same precipitating reaction in shells also occurs in carbonate mud. But geologists assumed the isotope balance in carbonate muds would be more vulnerable to chemical changes.

    “People have often overlooked mud. They thought that if you try to use it as a temperature indicator, you might be looking at not the original ocean temperature in which it formed, but the temperature of a process that occurred later on, when the mud was buried a mile below the surface,” Goldberg says.

    To see whether carbonate muds might preserve signatures of their original surrounding temperature, the team used “clumped isotope geochemistry,” a technique used in Bergmann’s lab, which analyzes sediments for clumping, or pairing, of two heavy isotopes: oxygen-18 and carbon-13. The likelihood of these isotopes pairing up in carbonate muds depends on temperature but is unaffected by the ocean chemistry in which the muds form.

    Combining this analysis with traditional oxygen isotope measurements provides additional constraints on the conditions experienced by a sample between its original formation and the present. The team reasoned that this analysis could be a good indication of whether carbonate muds remained unchanged in composition since their formation. By extension, this could mean the oxygen-18 to -16 ratio in some muds accurately represents the original temperature at which the rocks formed, enabling their use as a climate record.

    Ups and downs

    The researchers tested their idea on samples of carbonate muds that they extracted from two sites, one in Svalbard, an archipelago in the Arctic Ocean, and the other in western Newfoundland. Both sites are known for their exposed rocks that date back to the early Paleozoic era.

    In 2016 and 2017, teams traveled first to Svalbard, then Newfoundland, to collect samples of carbonate muds from layers of deposited sediment spanning a period of 70 million years, from the mid-Cambrian, when animals began to flourish on Earth, through the Ordovician periods of the Paleozoic era.

    When they analyzed the samples for clumped isotopes, they found that many of the rocks had experienced little chemical change since their formation. They used this result to compile the rocks’ oxygen isotope ratios from 10 different early Paleozoic sites to calculate the temperatures at which the rocks formed. The temperatures calculated from most of these sites were similar to previously published lower-resolution fossil temperature records. In the end, they mapped a timeline of temperature during the early Paleozoic and compared this with the fossil record from that period, to show that temperature had a big effect on the diversity of life on the planet.

    “We found that when it was warmer at the end of the Cambrian and early Ordovician, there was also a peak in microbial abundance,” Goldberg says. “From there it cooled off going into the middle to late Ordovician, when we see abundant animal fossils, before a substantial ice age ends the Ordovician. Previously people could only observe general trends using fossils. Because we used a material that’s very abundant, we could create a higher-resolution record and could see more clearly defined ups and downs.”

    “This is the best recent isotopic study addressing the critical question of whether early animals experienced hot early temperatures,” says Ethan Grossman, a professor of geology at Texas A&M University, who was not a contributor to the study. “We should use all the tools at our disposal to explore this important time interval.”

    The team is now looking to analyze older muds, dating back before the appearance of animals, to gauge the Earth’s temperature changes prior to 540 million years ago.

    “To go back beyond 540 million years ago, we have to grapple with carbonate muds, because they are really one of the few records we have to constrain climate in the distant past,” Bergmann says.

    See the full article here .


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  • richardmitnick 10:58 pm on December 21, 2020 Permalink | Reply
    Tags: "Volcanic eruptions directly triggered ocean acidification during Early Cretaceous", , During this age in the Early Cretaceous Period -OAE1a- an entire family of sea-dwelling nannoplankton virtually disappeared., , , Nannoplankton and many other marine organisms build their shells out of calcium carbonate., Northwestern researchers examined a 1600-meter-long sediment core taken from the mid-Pacific Mountains., , OAE-oceanic anoxic event, Paleogeology, The Ontong Java Plateau large igneous province (LIP) erupted for seven million years., Thermal ionization mass spectrometry, When atmospheric CO2 dissolves in seawater it forms a weak acid that can inhibit calcium carbonate formation and may even dissolve preexisting carbonate.   

    From Northwestern University: “Volcanic eruptions directly triggered ocean acidification during Early Cretaceous” 

    Northwestern U bloc
    From Northwestern University

    December 21, 2020
    Amanda Morris

    1
    Calcium carbonate samples from a sediment core drilled from the mid-Pacific Mountains.

    Around 120 million years ago, the earth experienced an extreme environmental disruption that choked oxygen from its oceans.

    Known as oceanic anoxic event (OAE) 1a, the oxygen-deprived water led to a minor — but significant — mass extinction that affected the entire globe. During this age in the Early Cretaceous Period, an entire family of sea-dwelling nannoplankton virtually disappeared.

    By measuring calcium and strontium isotope abundances in nannoplankton fossils, Northwestern earth scientists have concluded the eruption of the Ontong Java Plateau large igneous province (LIP) directly triggered OAE1a. Roughly the size of Alaska, the Ontong Java LIP erupted for seven million years, making it one of the largest known LIP events ever. During this time, it spewed tons of carbon dioxide (CO2) into the atmosphere, pushing Earth into a greenhouse period that acidified seawater and suffocated the oceans.

    “We go back in time to study greenhouse periods because Earth is headed toward another greenhouse period now,” said Jiuyuan Wang, a Northwestern Ph.D. student and first author of the study. “The only way to look into the future is to understand the past.”

    The study was published online last week (Dec. 16) in the journal Geology. It is the first study to apply stable strontium isotope measurements to the study of ancient ocean anoxic events.

    Andrew Jacobson, Bradley Sageman and Matthew Hurtgen — all professors of earth and planetary sciences at Northwestern’s Weinberg College of Arts and Sciences — coauthored the paper. Wang is co-advised by all three professors.

    Clues inside cores

    Nannoplankton and many other marine organisms build their shells out of calcium carbonate, which is the same mineral found in chalk, limestone and some antacid tablets. When atmospheric CO2 dissolves in seawater, it forms a weak acid that can inhibit calcium carbonate formation and may even dissolve preexisting carbonate.

    To study the earth’s climate during the Early Cretaceous, the Northwestern researchers examined a 1,600-meter-long sediment core taken from the mid-Pacific Mountains. The carbonates in the core formed in a shallow-water, tropical environment approximately 127 to 100 million years ago and are presently found in the deep ocean.

    “When you consider the Earth’s carbon cycle, carbonate is one of the biggest reservoirs for carbon,” Sageman said. “When the ocean acidifies, it basically melts the carbonate. We can see this process impacting the biomineralization process of organisms that use carbonate to build their shells and skeletons right now, and it is a consequence of the observed increase in atmospheric CO2 due to human activities.”

    Strontium as corroborating evidence

    Several previous studies have analyzed the calcium isotope composition of marine carbonate from the geologic past. The data can be interpreted in a variety of ways, however, and calcium carbonate can change throughout time, obscuring signals acquired during its formation. In this study, the Northwestern researchers also analyzed stable isotopes of strontium — a trace element found in carbonate fossils — to gain a fuller picture.

    “Calcium isotope data can be interpreted in a variety of ways,” Jacobson said. “Our study exploits observations that calcium and strontium isotopes behave similarly during calcium carbonate formation, but not during alteration that occurs upon burial. In this study, the calcium-strontium isotope ‘multi-proxy’ provides strong evidence that the signals are ‘primary’ and relate to the chemistry of seawater during OAE1a.”

    “Stable strontium isotopes are less likely to undergo physical or chemical alteration over time,” Wang added. “Calcium isotopes, on the other hand, can be easily altered under certain conditions.”

    The team analyzed calcium and strontium isotopes using high-precision techniques in Jacobson’s clean laboratory at Northwestern. The methods involve dissolving carbonate samples and separating the elements, followed by analysis with a thermal ionization mass spectrometer.

    Researchers have long suspected that LIP eruptions cause ocean acidification. “There is a direct link between ocean acidification and atmospheric CO2 levels,” Jacobson said. “Our study provides key evidence linking eruption of the Ontong Java Plateau LIP to ocean acidification. This is something people expected should be the case based on clues from the fossil record, but geochemical data were lacking.”

    Modeling future warming

    By understanding how oceans responded to extreme warming and increased atmospheric CO2, researchers can better understand how earth is responding to current, human-caused climate change. Humans are currently pushing the earth into a new climate, which is acidifying the oceans and likely causing another mass extinction.

    “The difference between past greenhouse periods and current human-caused warming is in the timescale,” Sageman said. “Past events have unfolded over tens of thousands to millions of years. We’re making the same level of warming (or more) happen in less than 200 years.”

    “The best way we can understand the future is through computer modeling,” Jacobson added. “We need climate data from the past to help shape more accurate models of the future.”

    The study, “Stable Ca and Sr isotopes support volcanically-triggered biocalcification crisis during Oceanic Anoxic Event 1a,” was supported by the David and Lucile Packard Foundation (award number 2007-31757) and the National Science Foundation (award number EAR-0723151). This work was jump-started with supported from the Ubben Program for Climate and Carbon Science at Northwestern University, which funded previous, related work on the topic.

    See the full article here .

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    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
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