Greening the Earth

Late Precambrian carbonate outcropping is visable at the south end of Death Valley, California. Carbon isotopes in these layers bear evidence of the first extensive greening of the Earth
One of the most dramatic and seemingly inexplicable events in the history of Earth’s biosphere occurred roughly 540 million years ago when multi-cellular life exploded all over the planet. This large-scale diversification of life is known as the ‘Cambrian explosion’ and lead to the variety of organisms we see on Earth today. Scientists have often attributed the Cambrian explosion to significant geologic or climatic changes on our planet, but new NASA-sponsored research may have a better explanation.

Rather than catastrophic disruptions in Earth’s climate, a new study indicates that the Cambrian explosion may have been caused by more...

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Source: [Nature]

August 26, 2009 / Written by: Aaron Gronstal

Rock Bands Spin an Oxygen Record

The rise of oxygen on early Earth may have been caused by a microbial changing of the guard between methane-producers and oxygen-producers. This swap may have been initiated by a drop in the ocean’s nickel abundance. Continuing studies of the world’s largest iron ore deposits could cement the case.

Source: [Astrobiology Magazine]

June 22, 2009 / Written by: Michael Schirber

Evidence for the Great Oxidation Event Challenged

The timing of the rise of oxygen in Earth’s atmosphere is a key question in astrobiology. It is coupled not only to the question of when organisms capable of oxygenic photosynthesis first evolved on Earth, but also what signs of life might be found on young Earth-like planets around other stars.

Members of NAI’s Penn State and Carnegie Institution of Washington Teams report in the current issue of Science that certain sulfur isotopes found in many sedimentary rocks older than 2.4 billion years may not be the result of photochemical reactions in an oxygen-free atmosphere as previously thought....

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April 17, 2009 / Posted by: Daniella Scalice

Early Oxygen

Cores retrieved from layers of deep-sea rocks that are 3.46 billion years old suggest that oceans contained abundant oxygen and that the atmosphere of the Earth was as rich in oxygen as it is today. The cores were obtained in northwestern Western Australia, and contain evidence that the deep ocean 3.46 billion years ago was so rich in oxygen that oxygen-producing organisms must have been actively producing it. This means that oxygen-producing organisms like cyanobacteria were present much earlier in Earth’s history than previously believed.

Source: [Astrobiology Magazine]

March 28, 2009 / Posted by: Aaron Gronstal

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.

Source: [Link]

October 11, 2007 / Posted by: Shige Abe

Oxygen in Earth's Atmosphere Before Great Oxidation Event

NAI’s Astrobiology Drilling Program supported researchers in 2004 to obtain subsurface core samples from the Hamersley Basin in Western Australia. Those samples, representing the time just before the Great Oxidation Event, have been analyzed, and two research papers detailing the results (Anbar, et al. and Kaufman, et al.) appear in September 28, 2007 issue of Science. Both groups found unexpected, correlated changes that reveal the presence of small but significant amounts of O2 in the environment 2.5 billion years ago, ~50-100 milion years before the Great Oxidation Event, and a shift from lower O2 abundance prior to that time.

Source: [Link]

September 28, 2007 / Posted by: Shige Abe

Subaerial Volcanoes Shift Oxygen Levels on Early Earth

Biomarkers in rocks prior to the rise in Earth’s atmospheric oxygen 2.5 billion years ago show cyanobacteria released oxygen at the same levels as today. What was happening to that oxygen? A new paper in this week’s Nature from NAI’s Penn State Team proposes that the rise of atmospheric oxygen occurred because the predominant sink for oxygen—enhanced submarine volcanism—was abruptly and permanently diminished during the Archaean–Proterozoic transition by a shift from predominantly submarine volcanism to a mix of subaerial and submarine volcanism.

Source: [Link]

August 31, 2007 / Posted by: Shige Abe

Biogeochemistry and Oxygenic Photosynthesis

Researchers from NAI’s University of Colorado, Boulder Team recently reported in Earth and Planetary Science Letters their new biogeochemical model relating to the Great Oxidation Event. With ion microprobe data for individual sulfides from water-lain sedimentary units in the 2.45–2.22 Ga Huronian Supergroup, the team proposes a new model where enhanced weathering rates during interglacial thawing stimulated blooms of oxygenic photosynthesis, the demise of methane, and ultimately the irreversible rise in atmospheric oxygen between the first and second Huronian glaciations. The paper’s lead author was also the recipient of an NAI Research Scholarship in 2004.

Source: [Link]

February 8, 2007 / Posted by: Shige Abe

Oxygen and Life in the Precambrian

The December 2006 issue of Geobiology is a collection of papers focusing on the history of Earth’s biogeochemistry, from the earliest sedimentary rocks in Greenland to the late Proterozoic. The rise of atmospheric oxygen provides a thematic link. The papers in this issue, edited by David Catling and Roger Buick of NAI’s University of Washington Alumni Team, grew out of a session of the Earth System Processes 2 conference in Calgary, Canada, 8–11 August 2005, sponsored by the NAI.

Source: [Link]

November 27, 2006 / Posted by: Shige Abe

Romer's Gap Confirmed

Peter Ward from NAI’s Alumni Team at the University of Washington and his collaborators have a new paper out in PNAS this week providing supportive evidence for Romer’s Gap. Their results link this gap in vertebrate terrestrialization with a low atmospheric oxygen interval. This paper supports Ward’s new book on the evolution of effective respiratory systems, entitled “Out of Thin Air.”

Source: [Link]

October 25, 2006 / Posted by: Shige Abe

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.

Source: [Link]

November 29, 2005 / Posted by: Shige Abe

More on the Rise of Earth's Oxygen Levels

A new paper in Earth and Planetary Science Letters from NAI’s Carnegie Institution of Washington Lead Team and NAI’s International Partner, the Australian Centre for Astrobiology, explores environmental changes during the rise of atmospheric oxygen and the relationship between tectonics, atmospheric oxygen, and climatic changes.

Source: [Link]

October 17, 2005 / Posted by: Shige Abe