Content with the tag: “early earth”
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Iron Isotope Record Reflects Microbial Metabolism Through Time
NAI’s University of Wisconsin team presents a review of iron isotope fingerprints created through biogeochemical cycling in the May, 2008 issue of Annual Review of Earth and Planetary Sciences. This landmark paper brings together for the first time the co-evolution records of photosynthesis, bacterial sulfate reduction, and bacterial iron reduction in the early Earth. They review data on natural systems and experiments, looking at both abiological and biological processes, and conclude that the temporal carbon, sulfur,...
August 27, 2008 / Posted by: Daniella Scalice
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Jack Hills Zircons: New Information About Earth's Earliest Crust
Members of NAI’s University of Wisconsin, Madison team have a new paper in Earth and Planetary Science Letters presenting their analyses of 4.35 – 3.36 billion year old detrital zircons from the Jack Hills, Western Australia. Their data reveal relatively high lithium abundances compared to other zircons, as well as lithium isotope ratios that are similar to continental crust weathering products rather than ocean floor basalts. The results support the hypothesis that continental-type crust and oceans existed...
August 27, 2008 / Posted by: Daniella Scalice
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Oxygen in Earth's Early Atmosphere
Researchers from NAI’s Carnegie Institution of Washington Team have a paper in this week’s Nature describing evidence that Earth’s Mesoarchean atmosphere (3.2 and 2.8 Gya) possessed very low amounts oxygen. These findings contrast with prior claims that Earth’s atmosphere underwent its first rise in oxygen during the Mesoarchean, and indicate that oxygen first rose above parts per million levels sometime between 2.45 and 2.4 billion years ago.
October 10, 2007 / Posted by: Shige Abe
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Oceans from Comets, A How-To
Last week, teachers in the SETI Institute’s Astrobiology Summer Science Experience workshop probed questions about the Earth’s formation, including “where did the water come from?” The answer discussed was comets, and a classroom activity on how to make them is shared on Space.com…
July 1, 2007 / Posted by: Shige Abe
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Greenhouse Gases on Early Earth Helped Keep It Warm
A team of researchers including members of NAI’s University of Colorado, Boulder Team have provided the first direct field evidence supporting the theory that high concentrations of greenhouse gases could have helped avoid global freezing on the early Earth. They analyzed iron carbonates from 3.75-3.8 billion year old rocks in northern Québec, and conclude that the atmosphere of early Earth contained high levels of CO2. Their paper appears in a recent issue of Earth and Planetary Science Letters.
February 6, 2007 / Posted by: Shige Abe
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Organic Hazes on Early Earth and Titan
Researchers from NAI’s Unviersity of Colorado, Boulder and University of Arizona Teams have published a new study in PNAS this week about the atmospheres of both present day Titan and early Earth. For Titan, their experiments modeled conditions measured by the Huygens probe from NASA’s Cassini mission, and CO2 was added to model the early Earth conditions. They conclude that organize haze can form over a wide range of methane and carbon dioxide concentrations.
November 6, 2006 / Posted by: Shige Abe
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NASA Study Shows Titan and Early Earth Atmospheres are Similar
Organic haze in the atmosphere of Saturn’s moon, Titan, is similar to haze in early Earth’s air — haze that may have helped nourish life on our planet— according to a NASA Astrobiology Institute study released Nov. 6, 2006.
November 5, 2006 / Posted by: Shige Abe
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Photosynthesis in the late Archean
A new study on carbon isotopes in sedimentary rocks from Western Australia by researchers from NAI’s Penn State and Carnegie Institution of Washington Teams supports the idea that small, shallow pools of water containing photosynthetic microbes existed on the early Earth ~ 2.72 Gya, about 300 million years before the rise of oxygen in the atmosphere. Their findings suggest a “global-scale expansion” of these habitats, and a progression away from anaerobic ecosystems and toward photosynthetic communities before the oxygenation...
October 16, 2006 / Posted by: Shige Abe
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A New Book on the Evoution of Earth's Early Atmosphere
With significant contribution from NAI’s Penn State University Team, a new book entitled “Evolution of Early Earth’s Atmosphere, Hydrosphere, and Biosphere – Constraints from Ore Deposits”, edited by Stephen E. Kesler and Hiroshi Ohmoto, is available. It grew from a 2002 Pardee Symposium held during the Geological Society of America Annual Meeting sponsored in part by the NAI.
September 7, 2006 / Posted by: Shige Abe
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Earlier Evolution of Oxygenic Photosynthesis - Surviving Snowball Earth
Roger Buick from NAI’s University of Washington Team and his colleagues report in the current issue of Geology their analysis of oil-bearing fluid inclusions in 2.45 billion year old rocks from Canada. They assert that the oil is derived from an overlying formation, becoming trapped in the host rock before 2.2 billion years ago – prior to the Great Oxidation Event. Abundant biomarkers for cyanobacteria and eukaryotes were identified in the study, suggesting that aqueous environments at the time...
June 13, 2006 / Posted by: Shige Abe
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Biodiversity Rocks the Cover of Nature
The cover of this week’s Nature belongs to Abigail Allwood of the Australian Centre for Astrobiology, one of NAI’s International Partners. She and her colleagues put forward the latest research on the ancient rocks of the Pilbara Craton in Western Australia, which points to evidence of life on Earth 3.43 billion years ago. Their description of a shallow marine environment, and identification of seven stromatolite morphotypes makes a strong argument for early life. NAI supported Allwood’s work with...
June 6, 2006 / Posted by: Shige Abe
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Timelines for the Evolution of Cyanobacteria
Former NAI Principal Investigator, Andy Knoll of Harvard University, and colleagues discuss the evolution of cyanobacteria in their new paper, “The evolutionary diversification of cyanobacteria: Molecular-phylogenetic and paleontological perspectives” in the April 4th issue of PNAS. The evolutionary timeline has implications for the rise of atmospheric oxygen on Earth.
Image courtesy of Micro*scope
April 17, 2006 / Posted by: Shige Abe
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Habitable Conditions on the Early Earth
Direct information concerning the first 500 million years of Earth history – the Hadean Eon – is very limited, since practically no crustal rocks from that time have survived. We do know that the Earth collided much more frequently than it does today with asteroids and comets, as witnessed by the heavily cratered highlands of the Moon. Astronomers also tell us that the Sun was about 30 percent fainter then, so that the Earth may have been cold, unless there was a large greenhouse effect to trap the Sun’s heat and raise surface temperatures above the freezing point. Also of special interest is the apparent fact that life arose on Earth either during or shortly after the Hadean Eon.
January 23, 2006 / Posted by: Shige Abe
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Further Studies on the Rise of Atmospheric Oxygen
Lee Kump of NAI’s Pennsylvania State University Lead Team is co-author on a new paper in GSA Today examining the rise of atmospheric oxygen at the Archean-Proterozoic transition, 2.5-2.0 billion years ago. The team of international researchers studied sedimentary and volcanic rocks from the Fennoscandian Shield, which provides a fairly complete record of the hallmark events of that transition.
November 28, 2005 / Posted by: Shige Abe
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Astrobiologists Find Evidence of Early Life on Land
Scientists with NASA’s Astrobiology Institute have discovered evidence that microbial life emerged on land between 2.6 billion and 2.7 billion years ago, much earlier than previously thought.
January 17, 2001 / Posted by: Shige Abe
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Life Under Bombardment
Does Greenland give a clue as to whether life was seeded twice: ‘stock’ cultures surviving one big impact event? Life Under Bombardment looks for the evidence of our terrestrial past.
November 26, 2000 / Posted by: Shige Abe
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Leonid Meteors Yield Rich Astrobiology Research Results
In search of meteor showers, an airborne research mission indicates that the chemical precursors to life found in comet dust may well have survived a plunge into early Earth’s atmosphere.
November 26, 2000 / Posted by: Shige Abe
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