New research links continents to key transitions in Earth's oceans,
atmosphere and climate

Date:
February 1, 2022
Source:
University of Wisconsin Oshkosh
Summary:
A new study advances the understanding of the role that continents
have played in the chemical evolution of Earth's oceans, with
implications for understanding atmospheric oxygenation and global
climate oscillations.



FULL STORY ==========================================================================
A new study led by University of Wisconsin Oshkosh geologist
Timothy Paulsen and Michigan Tech geologist Chad Deering advances the understanding of the role that continents have played in the chemical
evolution of Earth's oceans, with implications for understanding
atmospheric oxygenation and global climate oscillations.


==========================================================================
The team of researchers analyzed a global database of the chemistry
of tiny zircon grains commonly found in the Earth's continental rock
record. The research team includes other scientists from Michigan
Technological University and ETH Zurich in Switzerland.

The study was featured on the cover of the February issue of GSA Today
by the Geological Society of America, which highlights timely, innovative articles that appeal to a broad geoscience audience.

"Oceans cover 70% of Earth's surface, setting it apart from the other terrestrial planets in the solar system," said Paulsen, the lead author
on the paper. "Geologists have long recognized that there have been
profound changes in ocean chemistry over time." Yet there are significant questions about the drivers for changes in ocean chemistry in Earth's
past, especially associated with the ancient rock record leading up to
the Cambrian explosion of life approximately 540 million years ago.

"Continents tend to be worn down by weathering and rivers tend to
transport this sediment to the oceans leaving scattered puzzle pieces for geologists to fit together," said Deering, a coauthor on the paper. "There
is increasing evidence that important pieces of the puzzle are found
in the ancient beach and river sediments produced through continental weathering and erosion." The researchers' findings, based on an analysis
of an exceptionally large zircon data set from sandstones recovered
from Earth's major continental landmasses, may signify key links in the evolution of the Earth's rock cycle and its oceans.

"Our results suggest that two major increases in continental input from
rivers draining the continents were related to the break-up and dispersal
of continents, which caused increased weathering and erosion of a higher proportion of radiogenic rocks and high-elevation continental crust,"
Paulsen said.

"Both episodes are curiously associated with snowball Earth glaciations
and associated steps in oxygenation of the atmosphere-ocean
system. Geologists have long recognized that oceans are required
to make continents. It would appear based on our analyses that the
continents, in turn, shape the Earth's oceans, atmosphere and climate." ========================================================================== 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 Bachman. Continental Magmatism and Uplift as the Primary
Driver for First-Order Oceanic 87Sr/86Sr Variability with
Implications for Global Climate and Atmospheric Oxygenation. GSA
Today, 2022; 32 (2): 4 DOI: 10.1130/GSATG526A.1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220201161052.htm

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