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  • richardmitnick 3:17 pm on February 20, 2020 Permalink | Reply
    Tags: "Victoria’s volcanic history confirms the state’s Aboriginal inhabitation before 34000 years", , Budj Bim Australian World Heritage property., , Paleogeology,   

    From University of Melbourne: “Victoria’s volcanic history confirms the state’s Aboriginal inhabitation before 34,000 years” 

    u-melbourne-bloc

    From University of Melbourne

    19 February 2020
    Dr Erin Matchan
    Professor David Phillips

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    Lake Surprise at Budj Bim, as it is today. (cafuego/Flickr/CC BY-SA 2.0)

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    Eugene von Guerard’s Tower Hill, 1855.

    New techniques for dating volcanic eruptions, a lone axe and Indigenous oral traditions give us a new minimum age for human occupation in Victoria.

    The questions of when people first arrived in Australia and the nature of their dispersal across the continent are subjects of ongoing debate.

    A lack of ceramic artefacts and permanent structures has resulted in an apparent scarcity of dateable archaeological sites older than about 10,000 years, yet what evidence there is suggests occupation across much of the continent for 30,000 or more years.

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    Budj Bim is the only Australian World Heritage property listed exclusively for its Aboriginal cultural values. Picture: AAP

    In western Victoria, the Budj Bim Cultural Landscape World Heritage Site in Victoria contains the world’s oldest known aquaculture system, built by the Gunditjmara People more than 6,000 years ago, near a volcano called the Budj Bim Volcanic Complex.

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    Crater of Mount Eccles (Victoria). Flickr: Crater of Mount Eccles (Victoria)

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    The Budj Bim Cultural Landcape was inscribed on the World Heritage List on 6 July 2019. https://www.environment.gov.au

    However, the Gunditjmara have lived in this area for much longer than this, and now, using a new volcanic activity dating technique and matching this with physical archaeological evidence and the rich oral traditions of the Gunditjmara people we have confirmed human habitation in this region at least 34,000 years ago [GeoScience World-Geology].

    Existing evidence for the oldest known human habitations in Australia comes largely from radiocarbon (¹⁴C) dating of charcoal, and optically stimulated luminescence (OSL) dating of quartz grains in rock shelter sediments.

    In southeastern Australia, only six sites (located in what are now Tasmania, New South Wales, and South Australia) older than 30,000 years are considered definitively dated by ¹⁴C and/or OSL methods, with ages spanning 37,000 – 50,000 years.

    There is a need for independent age constraints to test some of the more controversial ages and add to the sparse age record.

    The oral traditions of Australian Aboriginal peoples have enabled perpetuation of ecological knowledge across many generations, providing a valuable resource of archaeological information.

    Some surviving traditions appear to reference geological events such as volcanic eruptions, earthquakes, and meteorite impacts, and it has been proposed that some of these traditions may have been transmitted for thousands of years.

    Examples include oral traditions around the 7,000 year old Kinrara volcano in north Queensland [Quaternary Geochronology], and a number of oral traditions implying much lower sea levels than present day and dramatic differences in vegetation reflecting cooler climates that existed thousands of years ago.

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    Schematic map showing the location of recent lavas and confirmed >30,000 year-old occupation sites in south-eastern Australia. Picture: Supplied/Modified from Allen & O’Connell, 2014.

    The plains of western Victoria and south eastern South Australia are punctuated by a number of conspicuous small hills and remarkably circular lakes.

    These striking features are the remnants of volcanoes that are geologically very young. While the more than 400 individual volcanoes are considered to be extinct, the volcanic province of which they are a part, the Newer Volcanic Province, is regarded as active.

    This region includes the youngest volcanoes in Australia, Mount Gambier and Mount Schank, both around 5,000 years old.

    Although precise ages remain elusive, a number of other volcanoes in the Newer Volcanic Province are thought to have erupted within the last 100,000 years, and the people living in this region tens of thousands of years ago would no doubt have witnessed volcanic activity.

    However, in Australia, little archaeological evidence has been found beneath volcanic ash deposits and lava flows – perhaps because very few studies have looked for this.

    A single stone artefact, the ‘Bushfield axe’, was serendipitously discovered in the 1940s during sinking of a post hole through a sequence of finely layered volcanic ash from the Tower Hill Volcanic Complex, about 40 kilometres southeast of the Budj Bim Volcanic Complex (formerly Mount Eccles).

    This ash from Tower Hill has not previously been dated.

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    The age of Tower Hill, associated as it is with the Bushfield axe, represents the minimum age for human presence in Victoria. Picture: Mertie/Flickr

    The only previous estimation of the eruption age is from a combined OSL and ¹⁴C dating study of sediments above and below the volcanic ash, which gave an age of 35,000 ± 3,000 years.

    However, that study did not consider the archaeological implications of this age, probably because the existence of the Bushfield axe is not widely known.

    Previous ages for the Budj Bim Volcanic Complex are variable, largely derived from ¹⁴C dating of sediments in the crater lake (Lake Surprise) and swamps that formed after the lava modified the regional drainage system.

    The oldest of these swamp sediment ages, ~31,400 ± 400 years, represents a minimum age for eruption of the Budj Bim Volcanic Complex.

    This is consistent with ages of 33,600 ± 5,200 years and 39,600 ± 7,000 years determined by lava surface exposure dating methods, but the precise eruption age was not definitively known until now.

    Another dating technique, called argon-argon (or ⁴⁰Ar/³⁹Ar dating) has been used to date much older volcanoes, including nearby Mount Rouse (284,400 +/- 1,800 years.

    Technological improvements over the last decade, including work in our lab at the University of Melbourne’s School of Earth Sciences, have firmly established that ⁴⁰Ar/³⁹Ar dating, which relies on the rate of natural radioactive decay of potassium into argon in minerals, can be successfully applied to archaeological timescales.

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    Schematic geological map showing the location of volcanoes in the study area and the ⁴⁰Ar/³⁹Ar sampling locations. Picture: Supplied.

    In our study, published in the journal Geology, in collaboration with Professor Fred Jourdan and Dr Korien Oostingh at Curtin University, we applied the ⁴⁰Ar/³⁹Ar dating technique to a ‘lava bomb’ from the Tower Hill eruption sequence and to a sample from the Tyrendarra lava flow, the biggest lava flow from the Budj Bim Volcanic Complex.

    This study was supported by a University of Melbourne McCoy Seed Fund grant with Museum Victoria and an ARC Discovery Grant.

    These analyses produced lava eruption ages of 36,800 ± 3,800 ka for Tower Hill and 36,900 ± 3,100 for the Budj Bim Volcanic Complex.

    These ages fall within the range of ¹⁴C and OSL ages reported for the six earliest known occupation sites in southeastern Australia. The age of Tower Hill, associated as it is with the Bushfield axe, represents the minimum age for human presence in Victoria.

    And if oral traditions surrounding Budj Bim do indeed reference volcanic activity, this could mean that these are some of the longest-lived oral traditions in the world.

    See the full article here .


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    u-melbourne-campus

    The University of Melbourne (informally Melbourne University) is an Australian public research university located in Melbourne, Victoria. Founded in 1853, it is Australia’s second oldest university and the oldest in Victoria. Times Higher Education ranks Melbourne as 33rd in the world, while the Academic Ranking of World Universities places Melbourne 44th in the world (both first in Australia).

    Melbourne’s main campus is located in Parkville, an inner suburb north of the Melbourne central business district, with several other campuses located across Victoria. Melbourne is a sandstone university and a member of the Group of Eight, Universitas 21 and the Association of Pacific Rim Universities. Since 1872 various residential colleges have become affiliated with the university. There are 12 colleges located on the main campus and in nearby suburbs offering academic, sporting and cultural programs alongside accommodation for Melbourne students and faculty.

    Melbourne comprises 11 separate academic units and is associated with numerous institutes and research centres, including the Walter and Eliza Hall Institute of Medical Research, Florey Institute of Neuroscience and Mental Health, the Melbourne Institute of Applied Economic and Social Research and the Grattan Institute. Amongst Melbourne’s 15 graduate schools the Melbourne Business School, the Melbourne Law School and the Melbourne Medical School are particularly well regarded.

    Four Australian prime ministers and five governors-general have graduated from Melbourne. Nine Nobel laureates have been students or faculty, the most of any Australian university.

     
  • richardmitnick 11:10 am on February 14, 2020 Permalink | Reply
    Tags: "Antarctic Ice Cores Might Be Older Than Dirt", , Cosmogenic nuclide dating, , Paleogeology   

    From Eos: “Antarctic Ice Cores Might Be Older Than Dirt” 

    From AGU
    Eos news bloc

    From Eos

    6 February 2020 [Just now in social media]
    Jessie Hendricks
    contactjessiescience@gmail.com

    Using cosmogenic nuclide dating, scientists determined a 10-meter core just below the surface to be over a million years old.

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    Researchers in Ong Valley, Antarctica, take pit samples above the ice during a field mission. Pictured left to right: Dan Morgan (Vanderbilt University), Greg Balco (Berkeley Geochronology Center), and Marie Bergelin (University of North Dakota, Grand Forks). Credit: Jaakko Putkonen

    A little over 500 kilometers from McMurdo Station, nestled in the Transantarctic Mountain Range, is the Ong Valley. This small, arid valley is about 6 kilometers long by 2.5 kilometers wide, and records suggest it has been visited by fewer people than the Moon.

    Jaakko Putkonen, associate professor and director of the Harold Hamm School of Geology and Geological Engineering at the University of North Dakota, Grand Forks, has been to the Ong Valley three times. He loves being one of the few: “You never know what’s behind the big rock because nobody’s ever looked there,” he said. “There are no footprints anywhere. Nothing.”

    Marie Bergelin, Putkonen’s Ph.D. student, joined him on his 2017–2018 expedition, in which a critical research team from multiple universities drilled into the Ong Valley’s ice bed and recovered two 10-meter ice cores. Putkonen and Bergelin presented their findings during a poster session at AGU’s Fall Meeting 2019 in San Francisco, Calif.

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    Jaakko Putkonen holds up a piece of debris-laden ancient ice recovered from Ong Valley, Antarctica. Credit: Marie Bergelin.

    One of the oldest sections of the cores, according to Bergelin, is likely to be around 2.6 million years old and at least no younger than the dirt above it, which was dated at 1.6 million years old. Putkonen and Bergelin are quick to note that the core may be older or younger than 2.6 million years, however. Determining the date of ice is a complex process, Putkonen said, and the numbers come out more “as a range of scenarios” rather than one specific date.

    The trick to dating ice cores is not the ice itself, but quartz grains embedded in or around it. And the trick to preserving ice is the layer of dirt on top of it.

    Dating the Ice

    Scientists use cosmogenic nuclide dating [ArcticGlaciders.org], which analyzes isotopes produced in quartz by cosmic rays at or near Earth’s surface. “The longer time it’s exposed to the surface and sitting at the surface, the higher concentrations of isotopes build up,” Bergelin said.

    The cosmic rays that produce these isotopes penetrate only a few meters. Below that, the isotopes stop building up, which helps scientists predict the age of a subsection of Earth or ice containing the debris.

    Bergelin extracted quartz grains from the full length of a core to determine the age of the ice inside. As suspected, the oldest section was at the bottom of the core.

    Preserving the Ice

    It’s well known that a sufficient amount of debris acts as a shield for ice, preventing it from melting or sublimation, the process by which ice bypasses a liquid stage and turns directly into vapor. (Sublimation is common in extremely arid climates like Antarctica.) “The soil cover is critical to preserving [the ice],” Putkonen said, “but even then we don’t fully understand the [preservation] process.”

    What scientists do know is that as ice sublimates and disappears, dirt dispersed in the ice will be left behind. The more ice sublimates, the more layers of dirt and debris will build up. Eventually, this layer of dirt will become thick enough that it inhibits the ice underneath from sublimating. Less than 5 centimeters of the right kind of dirt will actually enhance the melting of ice, but a thicker layer, maybe around 30 centimeters or more, said Putkonen, “will act as an insulating blanket and preserve the ice.”

    Without the protection of 60 centimeters of dirt on top of the ice, the 10-meter cores collected by Putkonen and Bergelin might have sublimated away in just over 100 years. Instead, the ice in the core is over a million years old.

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    This partial section of one of the 10-meter ice cores was drilled from below a blanket of dirt in Ong Valley, Antarctica. Credit: Marie Bergelin

    Brenda Hall, a professor in the School of Earth and Climate Sciences at the University of Maine, wrote in an email to Eos, “Bergelin and Putkonen have demonstrated the great antiquity of the buried ice and its potential for providing a glimpse into an environment that existed in the distant past. Perhaps more exciting, their work implies that this site may not be a ‘one off’ location, but rather that there is potential for old ice throughout the Transantarctic Mountains that can be used to reconstruct Earth’s past.”

    Bergelin and Putkonen have already found pollen, DNA, dust, and atmospheric gases trapped inside of the ice cores, which they continue to analyze.

    “In a way this is like opening up a window into a snapshot of the past conditions,” Putkonen said. “Once we start understanding the system better, there could be opportunities for a whole new way of looking into paleoconditions through pockets of preserved ice.”

    See the full article here .

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    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 6:27 pm on January 27, 2020 Permalink | Reply
    Tags: "Hidden past of Earth’s oldest continents unearthed", , , , Paleogeology, University of St Andrews   

    From University of St Andrews: “Hidden past of Earth’s oldest continents unearthed” 

    U St Andrews bloc

    University of St Andrews

    27 January 2020

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    New international research led by the University of St Andrews presents a novel way to understand the structure and formation of our oldest continents.

    The research, published in the journal Earth and Planetary Science Letters reveals how the team from St Andrews, Greenland, Australia, Denmark, and Canada, used magmatic rocks, sourced from deep within the Earth, to sample the interior of cratons as a means to understand how they were formed.

    Cratons are the ancient, stable, heart of the Earth’s continents, and their formation was a pre-requisite for the evolution of complex life. The North Atlantic Craton extends from Northern Scotland through Greenland to North America, and contains the oldest crust known on Earth – up to 3.8 billion years old. How these ancient cratons were built is a major scientific debate, informing on one of the most fundamental questions in Earth science: when did plate tectonics begin operating?

    Plate tectonics – the cycle of rigid tectonic plates in constant horizontal motion across the surface of the planet – makes Earth unique within the rocky planets of the solar system. Plate tectonics started at some point after the Earth formed 4.6 billion years ago, but it is unclear exactly when. Some scientists believe craton formation occurred as a result of plate tectonics, whereby they were assembled via horizontal stacking of crust. Others believe cratons were formed through non-plate tectonic processes, growing via so-called “vertical tectonics”.

    The ability to understand the architecture of cratons and therefore how and when they were formed is, however, problematic, due to the difficulty in sampling rocks from within the deep crust and mantle, which in West Greenland is up to 250 km thick.

    To address this, the research team used deep-sourced magmatic rocks known as kimberlites to sample the deep parts of the North Atlantic Craton. Kimberlites, which are famous for bringing diamonds to the surface, originate from the upper mantle, more than 100 km below Earth’s surface. As they ascend through the craton, their magma collects pieces of crust along the way, pieces that are hidden at the surface. In this way, kimberlites can sample parts of the deep continent that are otherwise inaccessible.

    The researchers sampled a kimberlite from the coast of West Greenland, near Maniitsoq, and extracted from it microscopic zircon grains, each less than the width of a human hair, originating from crust deep within the craton. The team analysed these grains using high-precision laser ablation mass spectrometry.

    Analysis revealed the age and chemistry of the zircon grains, which suggested that beneath the 3.0 billion-years old crust which today forms the Maniitsoq region, lies much older 3.8 billion-year-old crust. This older crust is today only found at the surface 150 km south of the kimberlite locality. Therefore, for it to have been sampled by the kimberlite, parts of it must have been transported laterally beneath the crust that is now at the surface, sometime after 3.0 billion years ago.

    Lead scientist Dr Nick Gardiner of the School of Earth and Environmental Sciences, University of St Andrews, said: “The kimberlite sample offers up these ancient zircon grains which imply the North Atlantic Craton was assembled by horizontally stacking different-aged slices of continental crust, likely in the late Archaean Eon after 3.0 billion years ago. These findings imply some cratons were formed through plate tectonic processes.”

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    See the full article here .

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    U St Andrews campus

    St Andrews is made up from a variety of institutions, including three constituent colleges (United College, St Mary’s College, and St Leonard’s College) and 18 academic schools organised into four faculties. The university occupies historic and modern buildings located throughout the town. The academic year is divided into two terms, Martinmas and Candlemas. In term time, over one-third of the town’s population is either a staff member or student of the university. The student body is notably diverse: over 120 nationalities are represented with over 45% of its intake from countries outside the UK; about one-eighth of the students are from the rest of the EU and the remaining third are from overseas — 15% from North America alone. The university’s sport teams compete in BUCS competitions, and the student body is known for preserving ancient traditions such as Raisin Weekend, May Dip, and the wearing of distinctive academic dress.

     
  • richardmitnick 2:27 pm on January 17, 2020 Permalink | Reply
    Tags: "An evolving understanding of extinction", Capetown, Johannesburg, , , , Paleogeology, , South Africa natural wonders,   

    From University of the Witwatersrand, Johannesburg, South Africa via phys.org: “An evolving understanding of extinction” 

    From University of the Witwatersrand, Johannesburg, South Africa

    via

    phys.org

    January 17, 2020
    Christine Steininger
    Bruce Rubidge

    1
    Encyclopædia Britannica, Inc.

    Few things related to science capture the imagination more than the magic of worlds past. This includes the origins of life, dinosaurs, mass extinctions, meteorite impacts, and the evolution of our species. Understanding the evolution of life is central to the way we view ourselves and others and developing this field is thus critical.

    Furthermore, South Africa’s rich palaeontological, palaeo-anthropological and archaeological record provides a unique competitive advantage to local heritage-related scientists.

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    Images of the natural wonders of South Africa, various sources.

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    Capetown. No image credit

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    Johannesburg. Britannica

    Palaeosciences is the only discipline dedicated to understanding the origin and development of past life and its interactions with changing environments. It is the responsibility of these scientists to ensure understanding of the depth of our dependence on Earth as a life support system. Additionally, paleosciences research can provide knowledge of how to manage human interactions with the planet responsibly.

    As our knowledge of the Earth expands, we begin to realise far more synergy and mutualistic relationships with the biological world—built up over millions of years—in many of the fundamental processes to secure biodiversity, soils, water, minerals, energy, and other resources.

    South Africa rocks

    South Africa is poised to become a global leader in an area of geographic advantage.

    Because of the country’s immense diversity, antiquity, and continuity of geological, palaeontological, and archaeological records, and its rich genetic heritage, South Africa is unique in the world.


    The DST-NRF Center of Excellence in Paleosciences. Credit: Wits University

    The country boasts some of the most significant mineral deposits on Earth and preserves, amongst others, the oldest evidence of life on Earth from over 3,500-million years; the most distant ancestors of dinosaurs from 200-million years ago; and a remarkable record of human origins and achievements over four-million years.

    Erasing Earth

    The study of past biodiversity has recognised that five global extinction events have occurred in the last 500-million years, where between 65 percent and 95 percent of species went extinct over a relatively short period. South Africa has a record of four of these five extinction events. Many scientists consider that the Earth has now entered a new epoch—the Anthropocene. Like other transitions between geological eras, the marker for this transition is a mass extinction event, although this one—uniquely—is human-induced. And avoidable.

    The current rate of species extinction is estimated to be 10 to 1,000 times higher than the natural, background rate. This is likely to increase as habitat destruction, global change, and other human-induced stresses on the natural environment accelerate.

    South Africa is the only country in the world with the necessary fossil resources to undertake a research initiative over such an extensive period. Our fossil archives provide case studies throughout Earth’s history to understand how climactic and environmental change affect biodiversity.

    Decoding the mechanisms that lead to population extirpation [localised extinction] and ultimately species extinction under climate change is critical for scenario-planning, interpreting, and possibly predicting its impact on biodiversity and to inform policy to conserve South African biodiversity in future.

    See the full article here .

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    The University of the Witwatersrand, Johannesburg (/vətˈvɑːtəsrənt/), is a multi-campus South African public research university situated in the northern areas of central Johannesburg. It is more commonly known as Wits University or Wits (/vəts/ or /vɪts/). The university has its roots in the mining industry, as do Johannesburg and the Witwatersrand in general. Founded in 1896 as the South African School of Mines in Kimberley, it is the third oldest South African university in continuous operation.

    The university has an enrolment of 40,259 students as of 2018, of which approximately 20 percent live on campus in the university’s 17 residences. 63 percent of the university’s total enrolment is for undergraduate study, with 35 percent being postgraduate and the remaining 2 percent being Occasional Students.

    The 2017 Academic Ranking of World Universities (ARWU) places Wits University, with its overall score, as the highest ranked university in Africa. Wits was ranked as the top university in South Africa in the Center for World University Rankings (CWUR) in 2016. According to the CWUR rankings, Wits occupies this ranking position since 2014.

     
  • richardmitnick 1:00 pm on January 17, 2020 Permalink | Reply
    Tags: "In death of dinosaurs it was all about the asteroid — not volcanoes", , Cretaceous-Paleogene extinction event 66 million years ago, , , , Paleogeology, Site of the asteroid strike 66 million years ago is an impact crater buried underneath the Yucatán Peninsula in Mexico. The asteroid doomed the dinosaurs., The Chicxulub crater, , Walter and Luis Alvarez and Iridium,   

    From Yale University: “In death of dinosaurs, it was all about the asteroid — not volcanoes” 

    From Yale University

    January 16, 2020
    Jim Shelton

    1
    (© stock.adobe.com)

    Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers. It was all about the asteroid.

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    K-T boundary (red arrow) along Interstate 25, Raton Pass, Colorado. The Cretaceous–Paleogene boundary of 66 million years ago, marking the temporal border between the Cretaceous and Paleogene periods of geological time, was identified by a thin stratum of iridium-rich clay. During the 1970s, Walter Alvarez was doing geologic research in central Italy. There he had located an outcrop on the walls of a gorge whose limestone layers included strata both above and below the Cretaceous–Paleogene boundary. Exactly at the boundary is a thin layer of clay. Walter told his father Luis that the layer marked where the dinosaurs and much else became extinct and that nobody knew why, or what the clay was about — it was a big mystery and he intended to solve it. A team led by Luis Alvarez proposed in 1980 an extraterrestrial origin for this iridium, attributing it to an asteroid or comet impact. Their theory, known as the Alvarez hypothesis, is now widely accepted to explain the extinction of the non-avian dinosaurs. A large buried impact crater structure with an estimated age of about 66 million years was later identified under what is now the Yucatán Peninsula (the Chicxulub crater)

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    The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. It was formed by a large asteroid or comet about 11 to 81 kilometers in diameter, the Chicxulub impactor, striking the Earth, and causing the dinosaur extinction.

    In a break from a number of other recent studies, Yale assistant professor of geology & geophysics Pincelli Hull and her colleagues argue in a new research paper in Science that environmental impacts from massive volcanic eruptions in India in the region known as the Deccan Traps happened well before the Cretaceous-Paleogene extinction event 66 million years ago and therefore did not contribute to the mass extinction.

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    Deccan Traps at Ajanta Caves. Shaikh Munir

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    The hardened lava flows of the Deccan Traps, in western India. Gerta Keller

    Most scientists acknowledge that the mass extinction event, also known as K-Pg, occurred after an asteroid slammed into Earth. Some researchers also have focused on the role of volcanoes in K-Pg due to indications that volcanic activity happened around the same time.

    “Volcanoes can drive mass extinctions because they release lots of gases, like SO2 and CO2, that can alter the climate and acidify the world,” said Hull, lead author of the new study. “But recent work has focused on the timing of lava eruption rather than gas release.”

    To pinpoint the timing of volcanic gas emission, Hull and her colleagues compared global temperature change and the carbon isotopes (an isotope is an atom with a higher or lower number of neutrons than normal) from marine fossils with models of the climatic effect of CO2 release. They concluded that most of the gas release happened well before the asteroid impact — and that the asteroid was the sole driver of extinction.

    “Volcanic activity in the late Cretaceous caused a gradual global warming event of about two degrees, but not mass extinction,” said former Yale researcher Michael Henehan, who compiled the temperature records for the study. “A number of species moved toward the North and South poles but moved back well before the asteroid impact.”

    Added Hull, “A lot of people have speculated that volcanoes mattered to K-Pg, and we’re saying, ‘No, they didn’t.’”

    Recent work on the Deccan Traps, in India, has also pointed to massive eruptions in the immediate aftermath of the K-Pg mass extinction. These results have puzzled scientists because there is no warming event to match. The new study suggests an answer to this puzzle, as well.

    “The K-Pg extinction was a mass extinction and this profoundly altered the global carbon cycle,” said Yale postdoctoral associate Donald Penman, the study’s modeler. “Our results show that these changes would allow the ocean to absorb an enormous amount of CO2 on long time scales — perhaps hiding the warming effects of volcanism in the aftermath of the event.”

    German researcher André Bornemann was co-lead author of the study. Yale researcher Ellen Thomas was a co-author of the study, along with additional researchers from institutions in Germany, the United Kingdom, France, Spain, Japan, Denmark, and the United States.

    The International Ocean Discovery Program, the National Science Foundation, and Yale University helped fund the research.

    See the full article here .

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    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 9:10 am on December 31, 2019 Permalink | Reply
    Tags: "An Australian Crater Could Force Us to Rethink How We Judge a Planet's Age", , , , , , , , Paleogeology   

    From Curiosity: “An Australian Crater Could Force Us to Rethink How We Judge a Planet’s Age” 

    Curiosity Makes You Smarter

    From From Curiosity

    December 20, 2019
    Elizabeth Howell

    1
    Wolfe Creek Crater: the second largest meteor impact site in the world. Dainis Dravins – Lund Observatory, Sweden.

    A rock the size of a semitrailer that smacked Australia more than 100,000 years ago could help us better understand the universe. Astronomers just recalculated the age of an ancient desert crater [Meteoritics & Planetary Science] and discovered that it’s much younger than previously thought. By studying craters on Earth, we can better estimate how often comets and meteorites smacked into worlds around our solar system, thereby calculating their ages — and based on this work, we may have to rethink everything we know.

    Younger Than It Looks

    The scar of that ancient collision in Australia is called Wolfe Creek Crater, and it’s rather large, having been formed by a meteorite that was likely 50 feet (15 meters) in diameter. The object slammed into the desert and created a divot that’s been deemed the second largest crater on Earth from which fragments of the meteorite were recovered. Craters often disappear underwater or via geologic activity, so we’re lucky to have this find available to us.

    Scientists initially pegged the crater as 300,000 years old, putting it at about the same age as the human species. But the new estimate suggests it’s actually quite a bit younger, at only 120,000 years old, dating back to a warmer period on Earth known as the Eemian interglacial period. (On a side note, the Eemian is interesting to scientists studying climate change today, as some studies suggest our Earth nowadays is as warm as it was way back then.)

    How did this new age estimate arise? It was probably in part due to the fact that we have better scientific equipment than we did before. Also, researchers used two independent dating techniques: exposure dating, which estimates how long the sediment has been exposed to cosmic rays on the Earth’s surface, and optically stimulated luminescence, which measures how long ago sediment — in this case, sand buried after the impact — was last exposed to sunlight.

    “Results from the two dating techniques mutually support each other within the same age range,” said lead author Tim Barrows in a statement.

    Counting Craters

    Re-dating the crater in Australia has implications that could rock our solar system. There are planets and moons and tiny worlds with rocky surfaces all over our planetary neighborhood, some of the more famous being Mercury, the Moon, and Pluto. Astronomers estimate the age of their surfaces by using a technique called crater counting, which is exactly what it sounds like: They count the number of craters in an area and compare that number with an estimate of how often a small world smacks into the surface.

    Simply put, if scientists find a crater that’s younger than expected, that might mean that the rate of objects hitting Earth (and other worlds) slightly increases. With this new measurement, the research team estimates that large objects smack into our planet about once every 180 years or so. In roughly the last century, we know of two such events: an object that flattened 800 square miles (2,000 square kilometers) of forest in Tunguska, Siberia in 1908, and another that shattered glass and injured people when it broke up over the Russian town Chelyabinsk in 2013.

    NASA is, of course, on the case with a fleet of telescopes scanning the sky for any possible threats to Earth. Fortunately, they’ve found nothing pressing that could flatten a city, although they continue the search just in case — and they’re also aware that smaller objects (like Chelyabinsk) can still sneak through since they’re below the detection threshold of some telescopes. However, don’t lose any sleep yet. The agency will let us know if they find something worrying.

    In the meantime, the larger implication to take from this study is that the ages of craters all over the solar system may have to be reconsidered. The famous Meteor Crater in Arizona, for example, got a similar treatment from these researchers. They calculated that it’s likely to be 61,000 years old, which is about 10,000 years younger than previously estimated. So it will be interesting to see how this changes our understanding of ancient climates and life on our own planet — and on other worlds

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Curiosity Makes You Smarter

    Curiosity is on a mission to make learning easier and more fun than it has ever been. Our goal is to ignite curiosity and inspire people to learn. Each day, we create and curate engaging topics for millions of lifelong learners worldwide.

    Experience Curiosity on our website, through our apps and across social media. We designed Curiosity with your busy life in mind. Our editors find interesting and important topics that you’ll want to know more about, and introduce you to the best ways to keep learning.

    We hope you make Curiosity part of your daily digital diet. Never stop learning!

     
  • richardmitnick 8:32 am on December 9, 2019 Permalink | Reply
    Tags: "How Life on Our Planet Made It Through Snowball Earth", , , Paleogeology   

    From The New York Times: “How Life on Our Planet Made It Through Snowball Earth” 

    New York Times

    From The New York Times

    Dec. 2, 2019
    Lucas Joel

    1
    An artist’s concept of the Earth frozen in snow, during one of the planet’s most severe ice ages.Credit: Chris Butler/Science Source

    Rusty rocks left over from some of our planet’s most extreme ice ages hint at oases for survival beneath the freeze.

    Today, the world is warming. But from about 720 to 635 million years ago, temperatures swerved the other way as the planet became encased in ice during the two ice ages known as Snowball Earth.

    It happened fast, and within just a few thousand years or so, ice stretched over both land and sea, from the poles to the tropics. Life lived in the oceans at the time, and the encroaching ice entombed that life, cutting it off from both the sun and the atmosphere.

    “This is the one time when Earth’s natural thermostat broke,” said Noah Planavsky, a biogeochemist at Yale University. “The question on everyone’s minds was: How did life actually make it through this?”

    Glaciations can drive mass extinctions of life. Yet life, including perhaps our distant animal ancestors, somehow survived these deep freezes. In research published Monday in Proceedings of the National Academy of Sciences, Dr. Planavsky and his colleagues report the discovery of oases just beneath the ancient ice sheets that likely helped life persevere.

    Snowball Earth came to an abrupt end over a half-billion years ago, but its marks still exist in remote corners of the planet. In 2015, to reach one of those corners, Max Lechte and his graduate adviser at the time, Malcolm Wallace, both sedimentologists at the University of Melbourne, drove 15 hours into the South Australian outback.

    They trekked over hills made of red-colored rock, and it was so hot out — about 122 degrees Fahrenheit — that the soles of Dr. Wallace’s boots melted.

    “A bit of duct tape fixed that up,” said Dr. Lechte, who led the new research.

    These red-hot rocks formed in the oceans during the snowball glaciations, and their color caught Dr. Lechte’s eye, so he took a few samples. Then, in 2015 and 2016, he traveled to Namibia and Death Valley in California and found more rocks — also red — that formed at the same time.

    2
    The iron-rich rocks of Death Valley in California provide a window into Earth’s most severe ice age.Credit: Maxwell A. Lechte

    The rocks’ color signaled to Dr. Lechte that they are rich in iron, which means they turned red for the same reason that old cars with iron exteriors turn red: They rusted.

    Oxygen needs to be present for iron to rust. It also needs to be present for animals and many other organisms to survive. If the iron rocks below the ancient oceans rusted, then there was also oxygen in those oceans. And if there was oxygen, then oxygen-breathing life-forms had a lifeline they could cling to.

    “This is the first direct evidence for oxygen-rich marine environments during Snowball Earth,” said Dr. Lechte, now a postdoctoral researcher at McGill University in Canada.

    But how that oxygen got into the oceans in the first place was a mystery. The atmosphere is a major source of oxygen for the oceans, and with the ice sheets of Snowball Earth acting as giant air-blocking shields, oxygen in seawater should’ve been nonexistent.

    “This could’ve led to anoxic oceans, which could’ve killed off life-forms that need oxygen to survive.” Dr. Lechte said. “It presents a bit of an unsolved problem.”

    In labs at Yale as well as Nanjing University in China, Dr. Lechte and his team crushed the iron-rich rocks, dissolved them in acid and measured the abundances of different iron isotopes. They found that the iron in rocks that formed far out in the open oceans rusted much less than the iron in rocks that formed closer to land, right where ice sheets dove from continents and into the oceans.

    Today, beneath ice sheets in Antarctica, glacial meltwater streams flow into the Southern Ocean. That water melts from ice that can have air bubbles trapped inside it, and those bubbles can seed the meltwater streams with oxygen. On Snowball Earth, Dr. Planavsky explained, such oxygen-laden streams flowed into the oceans around the edges of continents and sustained life.

    Paul Hoffman, a geologist at Harvard University who pioneered the Snowball Earth hypothesis [Science], thinks this idea for how oxygen made it into the oceans is solid. “I’m attracted to the idea, and I think it’s consistent with my own observations,” he said.

    But, Dr. Hoffman added, whether or not this oxygen pump was the main thing that helped many living things survive those ice ages is still an open question.

    “We just don’t know enough from a theoretical standpoint about how life would have responded to the challenge of a Snowball Earth,” he said.

    See the full article here .

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

    Please help promote STEM in your local schools.

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  • richardmitnick 1:47 pm on November 6, 2019 Permalink | Reply
    Tags: "Exceptional Fossils May Need a Breath of Air to Form", , , Jackson School of Geosciences, Paleogeology, , , The best-preserved fossil deposits are called “Konservat-lagerstätten.”,   

    From University of Texas at Austin – Jackson School of Geosciences: “Exceptional Fossils May Need a Breath of Air to Form” 

    U Texas Austin bloc

    From University of Texas at Austin – Jackson School of Geosciences

    November 5, 2019

    1
    A fossilized mantle of a vampyropod, a relative tothe vampire squid. The ink sacis the raised structure in the center, and muscles have a striated appearance. Credit: Rowan Martindale/The University of Texas at Austin Jackson School of Geosciences.

    Some of the world’s most exquisite fossil beds were formed millions of years ago during time periods when the Earth’s oceans were largely without oxygen.

    That association has led paleontologists to believe that the world’s best-preserved fossil collections come from choked oceans. But research led by The University of Texas at Austin has found that while low oxygen environments set the stage, it takes a breath of air to catalyze the fossilization process.

    “The traditional thinking about these exceptionally preserved fossil sites is wrong,” said lead author Drew Muscente. “It is not the absence of oxygen that allows them to be preserved and fossilized. It is the presence of oxygen under the right circumstances.”

    The research was published in the journal PALAIOS on November 5.

    Muscente conducted the research during a postdoctoral research fellowship at the UT Jackson School of Geosciences. He is currently an assistant professor at Cornell College in Mount Vernon, Iowa. The research co-authors are Jackson School Assistant Professor Rowan Martindale, Jackson School undergraduate students Brooke Bogan and Abby Creighton and University of Missouri Associate Professor James Schiffbauer.

    The best-preserved fossil deposits are called “Konservat-lagerstätten.” They are rare and scientifically valuable because they preserve soft tissues along with hard ones – which in turn, preserves a greater variety of life from ancient ecosystems.

    “When you look at lagerstätten, what’s so interesting about them is everybody is there,” said Bogan. “You get a more complete picture of the animal and the environment, and those living in it.”

    The research examined the fossilization history of an exceptional fossil site located at Ya Ha Tinda Ranch in Canada’s Banff National Park. The site, which Martindale described in a 2017 paper [Geology], is known for its cache of delicate marine specimens from the Early Jurassic – such as lobsters and vampire squids with their ink sacks still intact—preserved in slabs of black shale.

    During the time of fossilization, about 183 million years ago, high global temperatures sapped oxygen from the oceans. To determine if the fossils did indeed form in an oxygen-deprived environment, the team analyzed minerals in the fossils. Since different minerals form under different chemical conditions, the research could determine if oxygen was present or not.

    “The cool thing about this work is that we can now understand the modes of formation of these different minerals as this organism fossilizes,” Martindale said. “A particular pathway can tell you about the oxygen conditions.”

    The analysis involved using a scanning electron microscope to detect the mineral makeup.

    “You pick points of interest that you think might tell you something about the composition,” said Creighton, who analyzed a number of specimens. “From there you can correlate to the specific minerals.”

    The workup revealed that the vast majority of the fossils are made of apatite – a phosphate-based mineral that needs oxygen to form. However, the research also found that the climatic conditions of a low-oxygen environment helped set the stage for fossilization once oxygen became available.

    That’s because periods of low ocean oxygen are linked to high global temperatures that raise sea levels and erode rock, which is a rich source of phosphate to help form fossils. If the low oxygen environment persisted, this sediment would simply release its phosphate into the ocean. But with oxygen around, the phosphate stays in the sediment where it could start the fossilization process.

    Muscente said that the apatite fossils of Ya Ha Tinda point to this mechanism.

    3
    A fossilized lobster claw that may come from a new species. Rowan Martindale, the University of Texas at Austin.

    The research team does not know the source of the oxygen. But Muscente wasn’t surprised to find evidence for it because the organisms that were fossilized would have needed to breathe oxygen when they were alive.

    The researchers plan to continue their work by analyzing specimens from exceptional fossil sites in Germany and the United Kingdom that were preserved around the same time as the Ya Ha Tinda specimens and compare their fossilization histories.

    The research was funded by the National Science Foundation and the Jackson School of Geosciences.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Texas at Austin

    U Texas Austin campus

    In 1839, the Congress of the Republic of Texas ordered that a site be set aside to meet the state’s higher education needs. After a series of delays over the next several decades, the state legislature reinvigorated the project in 1876, calling for the establishment of a “university of the first class.” Austin was selected as the site for the new university in 1881, and construction began on the original Main Building in November 1882. Less than one year later, on Sept. 15, 1883,

     
  • richardmitnick 1:53 pm on September 14, 2019 Permalink | Reply
    Tags: "Study Reveals Lost Continent Demolished by Europe", , Greater Adria, Paleogeology, ,   

    From smithsonian.com: “Study Reveals Lost Continent Demolished by Europe” 

    smithsonian
    From smithsonian.com

    Painstaking research recreates the history of Greater Adria, which slipped under the Eurasian plate 120 million years ago.

    September 13, 2019
    Jason Daley

    1
    Remnants of Greater Adria in the Taurus Mountains (Utrecht University)

    Researchers uncovered traces of a lost continent that disappeared under what is today Europe about 120 million years ago.

    Geologists have seen hints of the continent, dubbed Greater Adria, for years. But the Mediterranean area is incredibly complicated, so piecing together its history took a decade of academic detective work. “The Mediterranean region is quite simply a geological mess,” geologist Douwe van Hinsbergen of Utrecht University, first author of the study in Gondwana Research says. “Everything is curved, broken, and stacked.”

    The story that the rocks tell begins on the supercontinent Gondwana, which would eventually split into Africa, South America, Australia, Antarctica and India. Greater Adria broke away from the mother continent about 240 million years ago, beginning a slow drift northward. Roughly 140 million years ago, it was about the size of Greenland, mostly submerged in a tropical sea, collecting sediment that hardened into rock. Then, roughly 100 to 120 million years ago, it hit the southern edge of future Europe, spinning counterclockwise and moving at about 3 to 4 centimeters per year.

    As Robin George Andrews at National Geographic reports, the destruction of Greater Adria was complex. It hit several subduction zones, or areas where tectonic plates meet. In this case, the Greater Adria plate was trumped by the European plate, and most of it dove down into Earth’s mantle. The overlying plate scraped the top layers of Great Adria off. That debris eventually formed mountain ranges in Italy, Turkey, Greece, the Balkans and in the Alps. A few bits of Greater Adria escaped the plunge into the mantle and still exist in Italy and Croatia.

    Figuring out the story of Greater Adria was difficult, not only because of the geology but also due to human factors. Information about the continent is spread across many countries, from Spain to Iran. “Every country has their own geological survey and their own maps and their own stories and their own continents,” Hinsbergen tells Yasemin Saplakolu at LiveScience. “[With this study] we brought that all together in one big picture.”

    They also spent time constructing the continent’s history by examining the orientation of tiny magnetic minerals created by bacteria trapped in the Adria rocks. From that data they were able to understand how much the rock layers rotated over time. They also pieced together structures like strings of volcanoes and coral reefs. New, more powerful software developed over the last 15 years or so also aided in reconstructing the lost land mass.

    Sid Perkins at Science reports that the new study isn’t the only evidence for Greater Adria. In 2016, another team identified slabs of the continent in Earth’s mantle using seismic waves. Nor is it the only “lost continent” out there. A large land mass called Zealandia is submerged under two-thirds of a mile of water in the South Pacific and is considered the “eighth continent” by some researchers. In 2017, other scientists announced that they found a sunken “mini-continent” under the island of Mauritius in the Indian Ocean.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

     
  • richardmitnick 2:11 pm on August 8, 2019 Permalink | Reply
    Tags: , , , Metamorphic rocks are those that transform as they are buried and heated when tectonic plates grind together., Paleogeology, Plate Techtonics origins, Plate tectonics evolved gradually over the past 2.5 billion years as our planet slowly cooled   

    From Curtin University: “Curtin research helps solve mystery of when plate tectonics emerged” 

    From Curtin University

    8 August 2019

    Lucien Wilkinson
    Media Consultant
    Supporting Humanities and Science and Engineering
    Tel: +61 8 9266 9185
    Mob: +61 401 103 683
    lucien.wilkinson@curtin.edu.au

    Yasmine Phillips
    Media Relations Manager, Public Relations
    Tel: +61 8 9266 9085
    Mob: +61 401 103 877
    yasmine.phillips@curtin.edu.au

    New Curtin University research into how Earth’s rocks formed billions of years ago has helped unlock the mystery of how the planet’s unique plate tectonic behaviour changed over its more than four billion-year lifetime.

    1

    In the article. No image credit.

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

    The research, published in Nature today, found that by comparing the temperature, pressure and age of ancient rocks, it was revealed that plate tectonics evolved gradually over the past 2.5 billion years as our planet slowly cooled.

    Lead Australian researcher Dr Tim Johnson, from the School of Earth and Planetary Sciences at Curtin University, said the new research helped settle the ongoing debate of when and how earth’s plate tectonics system began.

    “Metamorphic rocks are those that transform as they are buried and heated when tectonic plates grind together. Not only are they exceptionally beautiful, they may also hold the key to unlocking the mystery of how Earth’s unique plate tectonic behaviour changed throughout time,” Dr Johnson said.

    “Some geologists consider that Earth has had plate tectonics throughout its four-and-a-half billion-year existence, whereas others consider that plate tectonics appeared abruptly some one billion years ago.

    “Using a simple statistical analysis of the temperature, pressure and age of metamorphic rocks, we have revealed that plate tectonics evolved gradually over the past 2.5 billion years as our planet slowly cooled.”

    Dr Johnson said a large focus of the research was on how Earth’s tectonic processes might have changed through the Proterozoic Eon, 2.5 billion to 0.54 billion years ago, which represents nearly half of Earth’s history.

    “There is debate as to whether the plate tectonic processes we observe today can be used to interpret really ancient rocks or if Earth’s tectonic processes were fundamentally different in the deep geological past,” Dr Johnson said.

    “Understanding how the ancient Earth was different to the modern Earth is key to accurately interpreting how Earth’s rocks formed and why they are distributed across the continents in the patterns that we see, including where mineral resources occur, how extensive they might be, and where additional resources might be found.”

    The research paper was co-authored by Dr Robert Holder and Professor Daniel Viete of Johns Hopkins University and Professor Michael Brown from the University of Maryland.

    See the full article here .

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

    Please help promote STEM in your local schools.

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    Curtin University (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 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.

     
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