Delineating primary and secondary organic carbon in neoproterozoic glacial sediments

Jun 16, 2010

How do we begin to understand what early life was like on Earth about 700 million years ago as our planet shifted from an oxygen-free and probably ice-covered realm to the oxygen-rich world that we know today?

One geochemist who decodes the early record of life on Earth has found a method featuring a combination of chemical analyses for a significantly clearer picture of this dynamic environment. Alison Olcott Marshall of the University of Kansas presented her findings today at the Goldschmidt Conference in Knoxville, Tenn. The conference is attended by several thousand geochemists and features new scientific discoveries regarding the Earth, energy and the environment. It is hosted by the University of Tennessee, Knoxville, and Oak Ridge National Laboratory.

Marshall is particularly interested in the time called , a period at the end of the Precambrian Era when geochemists speculate that the world was covered from pole to pole with glacial ice and the existing organisms lived exclusively in water. At that time life was still primarily single-cell organisms. So Marshall looks at chemical fossils to recreate the environment. The chemical complexes left from the cell walls of these organisms are more abundant and more easily classified than body fossils within the samples.

Marshall's research carries her to southeast Brazil, where there is stable sedimentary rock from the late Precambrian era. Her samples come from exploratory drilling that reached eight hundred meters down into the core of black shale that was at
the bottom of a sea 700 million years ago.

"The one caveat with biomarkers (chemical fossils) is that there is always a danger of contamination," Marshall said. Her initial tests using an instrument that looks at by molecular weight often had questionable results due to the possibility of contamination from material of a later period. However, by using another type of high resolution analysis called Raman spectroscopy, she also measured the subtle nuances of vibration that occur at the molecular level. Her high resolution results revealed two previously undetected distinctions in time generations.

Explore further: Antarctic ice sheet is result of CO2 decrease, not continental breakup

Provided by University of Tennessee at Knoxville

4.5 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

Looking for signs of early life

Jul 08, 2009

(PhysOrg.com) -- Deciphering the very early history of life on Earth is difficult. In the darkest recesses of the first billion years there are no 'body' fossils - no physical remains. Instead, scientists ...

Recommended for you

NASA sees zombie Tropical Depression Genevieve reborn

13 hours ago

Infrared imagery from NASA's Aqua satellite helped confirm that the remnant low pressure area of former Tropical Storm Genevieve has become a Zombie storm, and has been reborn as a tropical depression on ...

Wave energy impact on harbour operations investigated

17 hours ago

Infragravity period oscillations—waves that occur between 25 and 300 seconds with a wavelength between 100m and 10km—can have an impact on berthing operations, depending on a harbour's geometry.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

kevinrtrs
Jun 17, 2010
This comment has been removed by a moderator.
Skeptic_Heretic
not rated yet Jun 25, 2010
The article should state that "It is speculated that at that time, life was still primarily single-celled organisms" just as they were honest enough to show that the geologists are still speculating.
It is not speculated, it is evidenced. You are speculating that the planet is 6000 years old, regardless of the fact that there is zero evidence for this figure, including within your holy books.