Records from Lake Magadi in Kenya suggest environmental variability caused by changes in Earth’s orbit.


Deocampo et al. Collect samples of the Lake Magadi drill core at the National Lake Core Facility. Photo Provider Hominin Sites and Paleolakes Drilling Project. Credits: Photo credits Hominin Sites and Paleolakes Drilling Project.

The Rift Lake Valley in East Africa is home to diverse ecosystems, ranging from freshwater systems to highly alkaline systems. These Rift Valley lakes are also deposits and provide high-resolution environmental records that can be used to better understand the environmental and climatic conditions of human evolution over the last million years in East Africa. . To bring.

A new study published yesterday Geology Examine the geochemical records of drill core deposits collected in Lake Magadi – Saltwater, Alkaline Lake Located in the southern part of Kenya Lift. It provides nearly a million years of paleoenvironmental records of the rare Rift Valley Lake system.

Georgia State University lead author Dan Deocampo and a group of international co-authors drilled Lake Magadi as part of the Hominin and Paleolakes Site Drilling Project (HSPDP), which collected sediment core deep in the lake basins of the Great Rift Valley in East Africa. low.

“We are trying to understand how the Earth’s surface environment has changed over the past millions of years and how it has affected the earliest habitats of Hominini.” Deo Campo said. “We used many different indicators of the ancient environment to see how the environment has changed, how the habitat has changed, and therefore how the dangers and resources of the early Hominini changed over time. I understand how it has changed. “

Geochemical analysis of samples from Lake Magadi has shown some of the highest concentrations of elements such as molybdenum, arsenic and vanadium reported so far in lake sediments. The over-accumulation of these elements has never been observed in other lakes in East Africa and generally requires normal conditions. The normal state is that the lake water is both anaerobic and sulphurous, usually caused during negative water balance episodes such as drought.

A glimpse of Lake Magadi from the west shore. Photo Provider Hominin Sites and Paleolakes Drilling Project. Credits: Hominin sites and Paleolakes drilling project

“The amount of molybdenum accumulated in the sulphide-rich sediments of the lake does not tell us the structure of the habitat inhabited by the Hominini, but the variation between their normal and freshwater conditions. He will tell you. Changes in the environment. “

Deocampo and his co-authors found that Euxinia became common around 700,000 years ago and has since tended to occur at intervals where the Earth’s orbit becomes more elliptical. It happens every 100,000 years. As the Earth’s orbit becomes more elliptical, the Earth can move away from the Sun, causing more seasonal climate change. Lesse episodes are an important indicator of the severe drought that occurred in the region during the Generalized Ice Age.

These large-scale environmental changes that facilitated a shift between normal and well-mixed lake conditions would have had a significant impact on water availability and vegetation over the evolutionary timescale. ..

Records from Lake Magadi in Kenya suggest environmental variability caused by changes in Earth's orbit.

Dig the carrot of the site of Lake Magadi. Photo Provider Hominin Sites and Paleolakes Drilling Project. Credits: Photo credits Hominin Sites and Paleolakes Drilling Project.

The environmental variability suggested by geochemical records from Lake Magadi is associated with the renewal of mammalian species and the first emergence of Middle Stone Age technology in the southern Kenya Rift 500,000 to 320,000 years ago. I am.

“He’s a kind of paleoanthropologist who thinks about changes in the magnitude of environmental changes and their relationship to changes in gene pools and habitat structures, first and last appearances. It’s a touching point, ”explains Deocampo.


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For more information:
DM Deocampo et al, Pleistocene Euxinia Orbit Control on Lake Magadi, Kenya, Geology (2021). DOI: 10.1130 / G49140.1

Provided by
American Geological Society

Quote: Changes in Earth’s orbit obtained from https://phys.org/news/2021-09-lake-magadi-kenya-environmental- on September 21, 2021, according to records from Lake Magadi, Kenya (2021 ) The variability of the environment caused by (September 21, 2014) has been suggested. variability.html

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Records from Lake Magadi in Kenya suggest environmental variability caused by changes in Earth’s orbit.

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