A new study attempted to determine understanding of Earth’s crust by testing and debunking one popular hypothesis about why continental crust is lower in iron and more oxidized compared to oceanic crust. The iron-poor composition of the continental crust is the main reason why huge parts of the Earth’s surface stand above sea level as dry land, making terrestrial life possible today.
The research was conducted by Elizabeth Cottrell and Megan Holycross and showed through laboratory experiments that the oxidized, iron-depleted chemistry typical of the Earth’s continental crust probably did not originate from the crystallization of the mineral garnet.
Understanding of Earth’s crust by testing and debunking
One popular hypothesis about why continental crust is lower in iron and more oxidized compared to oceanic crust. The iron-poor composition of the continental crust is the main reason why huge parts of the Earth’s surface stand above sea level as dry land, making terrestrial life possible today.
The research was conducted by Elizabeth Cottrell and Megan Holycross and showed through laboratory experiments that the oxidized, iron-depleted chemistry typical of the Earth’s continental crust probably did not originate from the crystallization of the mineral garnet. The study helps to better understand the building blocks of the new continental crust.
The composition of the Earth’s iron-poor continental crust did not originate from the crystallization of the mineral garnet, as previously believed. The study attempted to determine the understanding of the Earth’s crust by testing and ultimately dispelling one popular hypothesis about why continental crust has less iron and is more oxidized compared to oceanic crust.
The research was conducted by Elizabeth Cottrell, a research geologist and curator of rocks at the Smithsonian’s National Museum of Natural History, and lead study author Megan Holycross, formerly a Peter Buck and National Science Foundation fellow at the museum and now an assistant professor at Cornell. University. The study uses laboratory experiments to show that the oxidized, iron-depleted chemistry typical of Earth’s continental crust likely did not originate from garnet crystallization.
The building blocks of the new continental crust emerge from deep within the Earth in places known as continental arc volcanoes, which are located in subduction zones where an oceanic plate sinks beneath a continental plate.
In the garnet explanation for the iron-depleted and oxidized state of the continental crust, the crystallization of garnet in the magmas beneath these continental arc volcanoes removes unoxidized (reduced or ferric, as it is known among scientists) iron from the Earth’s plates while depleting it. molten magma of iron and leaves it more oxidized.
One of the key consequences of the low iron content of Earth’s continental crust compared to oceanic crust is that continents are less dense and buoyant, causing continental plates to sit higher on the planet’s mantle than oceanic plates. This difference in density and buoyancy is the main reason why continents have dry land while oceanic crust is under water, and also why continental plates always rise to the top when they collide with oceanic plates.
The iron-poor composition of the continental crust is the main reason why huge parts of the Earth’s surface stand above sea level as dry land, making terrestrial life possible today. The study’s findings shed new light on our understanding of the Earth’s crust and the processes that shape our planet’s surface.
In the grand scheme of things, the study’s results suggest that the iron-depleted, oxidized chemistry of Earth’s continental crust likely did not originate from garnet crystallization, as previously believed. The results of the study provide new insight into the processes that shape the surface of our planet and help us better understand the composition of the Earth’s crust.
Written by: Vaishali verma
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