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Modelling and geochemical implications of intra-arc melting: consequences for the composition of the continental crust

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Mountain roots to mountain tops

EU-funded scientists focused on the boundaries of tectonic plates to shed light into the roots of mountain ranges.

Climate Change and Environment icon Climate Change and Environment

The uppermost layer of the mantle together with the crust form the rigid lithosphere of Earth, which is split up into plates moving relative to each other. The boundaries of tectonic plates are places where most of Earth's surface activity is concentrated. This is where the most active volcanoes are found and where, during volcanic eruptions, molten rock and gases that formerly lay deep within the mantle are forced skyward. But material that composes the plate moving under another is also recycled in the Earth's interior. Volcanic activity not only forms new islands, lava plains and mountain ranges, but also provided scientists working on the MELTARC project a brief glimpse into the dynamic processes that shape our planet. They had set out to examine the building blocks of exhumed island arcs at the Kohistan complex, near the continental margin of Asia and the Amalaoulaou complex in the Western Africa. At these two regions, the Asian and African continent are expected to be composed of rocks made of sediment laid on the ocean floor. Collisions between tectonic plates caused accretion of these deposits at the edges of the continents. Specifically, the MELTARC scientists described how compression, folding and faulting between the oceanic and continental plate created mountain ranges. On the other hand, investigation of the chemistry composition of the exposed roots of island arcs and the continental crust allowed them to establish several element and isotope ratios. These served as proxies for the processes operating within subduction zones. For example, friction between continental plates results in hot plumes of magma moving from the Earth's mantle upward, causing seafloor sediments to melt and mix up with mantle-derived magma. Scientists are still a long way from fully understanding volcano arcs or their role in shaping our planet and its atmosphere. But the MELTRAC project contributed to the body of knowledge that helps to define how the chemical exchange between the crust and the mantle influences the growth of continental crust.

Keywords

Mountain, root, tectonic plate, volcano, mantle, crust, ocean floor, magma, chemical composition

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