The story of the oceanic crust and the deep carbon cycle

Where does a story start? Or should we better ask: Where does it end? Some stories even run in circles, happening all the time. One of those stories is the global cycle of chemical elements, a topic many geoscientists are investigating. In the ABYSS project, we all study phenomena that are more or less related to the formation of new oceanic crust. That is the start of a story: magma from the Earth’s mantle rises underneath mid-ocean ridges, where plates are moving apart below kilometers of water; the magma crystallizes and the resulting rocks form these new plates. We can already tell a lot of stories about the processes that happen while new crust is formed, in this dynamic zone of interactions between water, rocks and magma. But in this post, I would like to put those into a larger context: the story does not end after the oceanic crust cools down and is carried away from the mid ocean ridges, where it formed.

MM1_fig_1.png
Sketch of the deep carbon cycle – how carbon is transported through Earth`s interior.

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Ocean crust: What is beneath the seafloor?

Have you ever thought about what happens beneath the oceans? What rocks below the seafloor might look like? And how we know about them?

Well, almost 70% of the Earth`s surface is covered by oceans. This means that ocean crust makes up the biggest part of the whole Earth’s surface, notably more than the continental crust that we live on! Continue reading

How to reproduce inner Earth pressure and temperature in a laboratory

Earth’s inner structure
Earth’s inner structure.

Drilling allows us to collect samples from the inner Earth, which provide us an idea of its composition and internal hidden processes.The deepest scientific drilling on Earth reached 12.262 km into the crust (Kola Superdeep Borehole in Russia), but what does it represent? The Earth has a radius of 6,378 km which is significantly greater than the 12 km of crust drilled at depth in Russia (Image 1). However it is extremely costly, time consuming, and for the moment there is no existing technology that would allow us to drill deep in the upper mantle (from 5 to 100 km deep). Therefore in order to complete our knowledge of Earth’s interior, geologists have to use different strategies, for example geophysical imaging. Another, less known possibility is experimental petrology, or “how to cook your own rocks”. Continue reading