John P. Grotzinger

Grotzinger during the WEF 2013

John P. Grotzinger (* 1957 ) is an American paleontologist .

life and work

Grotzinger received his bachelor's degree from Hobart College in 1979 and his master's degree from the University of Montana in 1981 . In 1985 he received his PhD from the Virginia Polytechnic Institute ( Evolution of Early Proterozoic passive-margin carbonate platform, Rocknest Formation, Wopmay Orogen, NWT, Canada ). In 1988 he became a professor at the Massachusetts Institute of Technology , where he was director of the Earth Resources Laboratory . In 1996 he became a visiting associate professor at Caltech , where he has been the Fletcher Jones Professor of Geology since 2005 and was also a Moore Scholar in 2004.

In 2007 he received the Charles Doolittle Walcott Medal for the study of fossil stromatolites in limestone and detailed field studies of the time course of early evolution. He also researches life possibilities on other planets for NASA, among others, and was involved in NASA's Mars Exploration Rover Project in 2003. In 2004 he and colleagues found evidence of water on Mars:

• Occurrence of small spheres 1 to 2 mm in diameter in the rocks with a random distribution without accumulation in certain layers,
• small disc-shaped cavities ( vugs ) about 1 cm long , possibly caused by dissolved gypsum crystals
• References to the mineral jarosite , an iron sulfate hydrate.

He is the lead scientist of the Mars Science Laboratory Rover Mission (2011). With Thomas H. Jordan (* 1948) he publishes the new editions of the widespread geology textbook Understanding Earth by Raymond Siever and Frank Press .

In 2002 he was admitted to the National Academy of Sciences and in 2019 to the American Academy of Arts and Sciences . He received the National Science Foundation Young Investigator Award, the Fred Donath Medal of the Geological Society of America, and the Henno Martin Medal of the Geological Society of Namibia.

In 2000 he described the with Cloudina oldest known metazoan fossils with calcareous skeletons, namacalathus , both from the small shelly fauna and found in the Nama Formation in Namibia - Cloudina back in the early 1970s, namacalathus by Grotzinger early 1990s (in the same Layers and together with Cloudina ).

Grotzinger also investigated the bio-geochemistry of Precambrian sediments, with techniques newly developed by him also being used in oil exploration. In doing so, he also found (after a one-year expedition to Oman in 2001, during which he examined samples from oil exploration from a depth of a few thousand meters, the then oldest bedrock in which oil was extracted), indications in support of his hypothesis about the puzzling origin of the Cambrian explosion (the relatively sudden development of the main animal phyla in the Cambrian around 540 million years ago). According to him, this was the result of a previous mass extinction in an environmental disaster that led to a lack of oxygen in the oceans due to a lack of circulation in the oceans. Cloudina and Namacalathus fossils disappeared into the layers during the transition to the Cambrian. In the distribution of the carbon isotopes, there were indications of a lack of oxygen as the cause, possibly as a result of the release of gases such as methane and carbon dioxide after the circulation in the oceans began again. Further investigation of rocks from Oman from the turn of the Precambrian to Cambrian (around 580 million years old) by Grotzinger and colleagues in 2006 showed evidence of better oxygen mixing even in deep areas of the oceans as a further cause of the Cambrian explosion.

Previously, other hypotheses had been favored, such as the development of hard shells that led to better conservation than fossils, or the advent of predators with corresponding evolutionary pressures.

John Grotzinger is an honorary member of the Geological Society of Oman.

Fonts

• with Frank Press , Thomas H. Jordan, Raymond Siever : General Geology . 5th edition, Spektrum Akademischer Verlag, Heidelberg / Berlin 2008 (original title: Understanding Earth, Freeman, New York, NY, 1993, translated by Volker Schweizer), ISBN 3-8274-1812-7 .
• with Thomas H. Jordan: The essential Earth , Freeman, New York, NY 2008, 2012, ISBN 978-1-429-25524-0 ( English ).

Individual evidence

1. ↑ Hobart Alumni Grotzinger ( Memento of the original dated November 17, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
2. ^ Official website of the Walcott Medal
3. ↑ NASA on the Walcott Prize for Grotzinger ( Memento of the original from September 30, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.  
4. ^ MIT News, 2004
5. ↑ Grotzinger, WA Watters, Andrew H. Knoll Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia. Paleobiology, Vol. 26, 2000, pp. 334-359
6. ↑ Andrew Knoll put forward a similar hypothesis
7. ^ Technology Review, MIT, March 2003 Evolutions missing link
8. ↑ Grotzinger, David Fike, Lisa Pratt, Roger Summons, Oxidation of the Ediacaran Ocean , Nature, Volume 44, p. 744. December 2006, Abstract , Just Breathe , Caltech 2006 ( Memento of the original from August 16, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 

Web links

• Homepage at Caltech