Ancient mountains recorded in Antarctic sandstones reveal potential
links to global events

Date:
August 5, 2020
Source:
University of Wisconsin Oshkosh
Summary:
A new analysis of sandstones from Antarctica indicates there may
be important links between the generation of mountain belts and
major transitions in Earth's atmosphere and oceans. A team of
researchers analyzed the chemistry of tiny zircon grains commonly
found in the Earth's continental rock record to determine their
ages and chemical compositions.



FULL STORY ==========================================================================
A new analysis of sandstones from Antarctica indicates there may be
important links between the generation of mountain belts and major
transitions in Earth's atmosphere and oceans.


==========================================================================
A team of researchers analyzed the chemistry of tiny zircon grains
commonly found in the Earth's continental rock record to determine their
ages and chemical compositions. The team included scientists from the University of Wisconsin Oshkosh, Michigan Technological University and
ETH Zurich in Switzerland.

The study was published recently in the international peer-reviewed
journal Terra Nova, which features short innovative papers about the
solid Earth and planetary sciences.

"Mountain building occurs in association with the plate tectonic
motions of the continents," said Paulsen, the lead author on the
paper. "Geologists have long recognized that the generation of significant mountainous relief has the potential to profoundly influence the chemistry
of the Earth's oceans and atmosphere." Yet there are significant
questions about the patterns of mountain building in Earth's past,
especially associated with the ancient rock record leading up to the
explosion of life about 541 million years ago.

"Mountains tend to be worn down by water and wind that ultimately
transports their sedimentary remains to the oceans, leaving an incomplete puzzle for geologists to fit together," said Deering, a coauthor on
the paper. "However, there is increasing evidence that missing pieces
of the puzzle are found in the sands of ancient beaches and rivers,
which are essentially the remnants of mountains produced by weathering
and erosion." The researchers' findings, based on an analysis of a
large sample of zircon grains from sandstone recovered in Antarctica,
may signify key links in the evolution of the Earth's rock cycle and
its atmosphere and oceans.

"We found two primary periods of increased average crustal thickness
associated with volcanic chains along convergent plate boundaries,
implying an increased proportion of higher mountains at these times,"
Paulsen said.

"Both episodes occurred during major reorganization of the continents when
they separated and drifted on the Earth's surface over time. They also
overlap with snowball Earth glaciations -- when the whole Earth was frozen
over -- and associated steps in oxygenation of the atmosphere, which may
have been critical for the evolution of life. These correlations suggest
an important causal link between plate tectonics and major transitions
in Earth's atmosphere and oceans."

========================================================================== Story Source: Materials provided by
University_of_Wisconsin_Oshkosh. Original written by Natalie
Johnson. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Timothy Paulsen, Chad Deering, Jakub Sliwinski, Snehamoy Chatterjee,
Olivier Bachmann, Marcel Guillong. Crustal thickness,
rift‐drift and potential links to key global events. Terra
Nova, 2020; DOI: 10.1111/ ter.12485 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200805102030.htm

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