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Geologists are interested in the sedimentary cycle—erosion from mountains that forms sand that is carried out to the ocean—because it’s foundational for understanding how the planet works.
It’s also crucial for understanding the global sand budget and planning offshore operations like oil extraction, wind farms, and carbon sequestration. Now, researchers have taken a broad look at ancient Earth’s sedimentary cycle during an extremely hot period in search of clues about the impacts of extreme climate events.
By synthesizing global data on deep-sea sand deposits, researchers identified a signal or “fingerprint” of extreme climate change from about 50 million years ago: turbidite deposits. These deposits, evidence of ancient rapid submarine water currents, are thought to be caused by the downslope transport of sediment that has accumulated at the top of the continental slope.
“This suggests that extreme weather events and exacerbated global climatic conditions contributing to increased erosion of landscapes could amplify delivery of sand into the deep ocean,” said Stanford University adjunct lecturer Zack Burton, lead author on a study detailing the findings published Feb. 8 in Scientific Reports.
High seas
The research challenges a long-held notion that sea-level changes are the dominant influence on sand deposits in the deep sea. When sea level is low, there’s a better chance for sediment eroded off mountains to find its way to the deep sea. Many researchers have theorized that high seas prevent sand from being deposited to deep seas because coastal plains and underwater continental shelves could be barriers to sand reaching deep waters.
But according to the study authors’ compilation of 59 instances of early Eocene turbidite systems active 56…
2023-02-08 05:00:02 How did ancient extreme climate affect sand in the deep sea?
Article from phys.org
In recent years, scientists have increasingly become aware of the changing climate of the Earth’s distant past and the subsequent impact on our world today. Part of this study focuses on how extreme climates from long ago shaped the deep ocean’s sediments.
Sediment in the deep sea is largely made up of a mix of silica, clay, and sand. A variety of processes, such as running water, wind and sea currents, result in particles accumulating over time to form vast deposits on the seafloor. Through research of core samples from the deep sea taken off the coasts of various countries, geologists have been able to piece together a picture of ancient climate cycles.
It has been established that during the last ice age, extreme climate conditions had a notable effect on deep-sea sediment. The colder temperatures brought lower ocean levels, exposing the continental shelves to greater wave action, which dissembled large sand and gravel grains, transporting them far out to deeper parts of the ocean.
On the other hand, during warmer temperatures, ocean levels would have been higher, resulting in more of these particles connecting with beaches and other shoreline structures. In addition, glaciers during the ice age were likely responsible for introducing large amounts of silt and clay particles, due to melting runoff.
Ultimately, by observing shifts in the different sediment types within core samples and through analysis of changing ocean levels, geologists are now better equipped to comprehend how ancient climates affected the malleable characteristics of deep sea sands.
From these findings, it is clear that extreme climate conditions previously experienced had an enduring impact on sediments in the deep sea, thereby allowing for a better understanding of present-day environment .