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Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. ... generally less than 10 kilometers thick; however, it is denser, ...
Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium).
Oceanic crust is thin (~6 km thick) and dense (about 3.3 g/cm 3), consisting of basalt, gabbro, and peridotite. Consequently, most oceanic crust is subducted easily at an oceanic trench. In contrast, continental crust is thick (~45 km thick) and buoyant, composed mostly of granitic rocks (average density about 2.5 g/cm 3).
Young oceanic lithosphere, found at mid-ocean ridges, is no thicker than the crust, but oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. The oldest oceanic lithosphere is typically about 140 kilometres (87 mi) thick. [ 3 ]
Oceanic crust is thinner than continental crust and is generally less than 10 km (6.2 mi) thick. Continental crust is about 35 km (22 mi) thick, but the large crustal root under the Tibetan Plateau is approximately 70 km (43 mi) thick. [4] The thickness of the upper mantle is about 640 km (400 mi). The entire mantle is about 2,900 km (1,800 mi ...
CLIP formed as a large igneous province and now forms a thickened zone of oceanic crust between the North American and South American plates. [2] In some places the oceanic crust is 2–3 times as thick as normal oceanic crust (15–20 km (9.3–12.4 mi) vs 7 km (4.3 mi). Its composition is similar to that of the Ontong Java Plateau. [3]
NASA/Goddard Space Flight Center The roughly 60,000-square-mile piece of crust has been hiding below the eastern Mediterranean Sea for about 340 million years (give or take 30 million years).
Continental crust is a tertiary crust, formed at subduction zones through recycling of subducted secondary (oceanic) crust. [17] The average age of Earth's current continental crust has been estimated to be about 2.0 billion years. [20] Most crustal rocks formed before 2.5 billion years ago are located in cratons.