Different Directions

Different Directions

Meteoritic Zircons Help Determine Age of Martian Crust

December 1st, 2013

By Sci-News.com

NWA (North West Africa) 7533 was unearthed by Bedouin tribesmen in the Sahara desert. It is a highlands breccia, which sets it apart from all other Martian meteorites. A breccia contains thousands of fragments of different geological samples and is the geological equivalent of a library containing the early history of Mars.

“As it turns out the crust is very old – about 4,430 million years old, which means that everything was happening very fast in the beginning on Mars,” said Dr Alexander Nemchin from Curtin University, a team member and the second author of a paper published in the journal Nature.

4.43-billion-year-old Martian meteorite NWA 7533. Image credit: Meteorites.tv.

4.43-billion-year-old Martian meteorite NWA 7533. Image credit: Meteorites.tv.



Bibliographic information
Humayun M et al. 2013. Origin and age of the earliest Martian crust from meteorite NWA 7533. Nature 503, pp. 513–516; doi: 10.1038/nature12764

3.48 Billion-Year-Old Fossilized Ecosystems

December 1st, 2013

Just found some time to look at this early Nov posting. Pushing the early Archean boundaries is really exciting.

From Nora Noffke et al. republished in Sci-News.com:

“The Pilbara region of Western Australia is one of the rare geological regions that provides insight into the early evolution of life on Earth,” explained Prof David Wacey from the University of Western Australia, who is a co-author of the paper published in the journal Astrobiology.

“Mound-like deposits created by ancient bacteria, called stromatolites, and microfossils of bacteria have previously been discovered in this region.”

“However, a phenomenon called microbially induced sedimentary structures had not previously been seen in rocks of this great age.”

Microbially induced sedimentary structures were created by microbial mats as the microbial communities responded to changes in physical sediment dynamics.

“A common example would be the binding together of sediment grains by microbes to prevent their erosion by water currents.”

“The significance of microbially induced sedimentary structures is that they not only demonstrate the presence of life, but also the presence of whole microbial ecosystems that could co-ordinate with one another to respond to changes in their environment.”

Left: 3.48 billion-year-old macrostructures from the Dresser Formation in Pilbara, Western Australia. Right: possible modern equivalents. Scale bars – 1 cm. Image credit: Nora Noffke et al.

Left: 3.48 billion-year-old macrostructures from the Dresser Formation in Pilbara, Western Australia. Right: possible modern equivalents. Scale bars – 1 cm. Image credit: Nora Noffke et al.


Bibliographic information
Nora Noffke et al. Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia. Astrobiology, published online November 8, 2013; doi: 10.1089/ast.2013.1030

Acid Rain, Ozone Depletion Contributed to Permian Extinction

November 30th, 2013

From Science Daily

Around 250 million years ago, at the end of the Permian period, there was a mass extinction so severe that it remains the most traumatic known species die-off in Earth’s history. Some researchers have suggested that this extinction was triggered by contemporaneous volcanic eruptions in Siberia. New results from a team including Director of Carnegie’s Department of Terrestrial Magnetism Linda Elkins-Tanton show that the atmospheric effects of these eruptions could have been devastating.

Base of the Siberian Traps volcanic sequence along Kotuy River in Arctic Siberia. (Credit: Image courtesy of Carnegie Institution)

Base of the Siberian Traps volcanic sequence along Kotuy River in Arctic Siberia. (Credit: Image courtesy of Carnegie Institution)

Journal Reference
B. A. Black, J.-F. Lamarque, C. A. Shields, L. T. Elkins-Tanton, J. T. Kiehl. Acid rain and ozone depletion from pulsed Siberian Traps magmatism. Geology, 2013; DOI: 10.1130/G34875.1

Controversial T. Rex Soft Tissue Find Finally Explained

November 28th, 2013

By Stephanie Pappas

The controversial discovery of 68-million-year-old soft tissue from the bones of a Tyrannosaurus rex finally has a physical explanation. According to new research, iron in the dinosaur’s body preserved the tissue before it could decay.

Credit: © Scott Hartman / All rights reserved

Credit: © Scott Hartman / All rights reserved

Earth’s Water Likely Came from Very Early Asteroid Strikes

October 27th, 2013

by Mike Wall, SPACE.com Senior Writer   |   October 25, 2013 11:56am ET

Earth got most of its water from asteroid impacts nearly 4.6 billion years ago, shortly after the solar system first took shape, a newstudy suggests.

An artist's illustration of a large asteroid headed for Earth. Credit: ESA

An artist’s illustration of a large asteroid headed for Earth.
Credit: ESA