Αποτελέσματα Αναζήτησης
1 Αυγ 2023 · The crust mainly consists of lighter rocks, such as basalt in the oceanic crust and granite in the continental crust. The Mohorovičić discontinuity, often referred to as the Moho, is the boundary between the Earth’s crust and the mantle.
Oceanic crust, the outermost layer of Earth’s lithosphere that is found under the oceans and formed at spreading centres on oceanic ridges, which occur at divergent plate boundaries. Oceanic crust is about 6 km (4 miles) thick. It is composed of several layers, not including the overlying sediment.
As we discussed in Chapter 10, oceanic crust is formed at sea-floor spreading ridges from magma generated by decompression melting of hot upward-moving mantle rock (Figure 10.18). About 10% of the mantle rock melts under these conditions, producing mafic magma.
1 Ιαν 2018 · Oceanic crust is the outermost solid layer of the lithospheric tectonic plates under the oceans that covers much of the Earth’s surface. It has a distinctive basaltic composition characterized by rocks that have relatively low concentrations of potassium and other highly incompatible trace elements (those typically excluded from minerals that ...
Tectonic lithosphere plates consist of lithospheric mantle overlain by either or both of two types of crustal material:oceanic crust (in older texts called sima from silicon and magnesium) and continental crust (sial from silicon andaluminium). Average oceanic lithosphere is typically 100 km (62 mi) thick; its thickness is a function of its age ...
The oldest large-scale oceanic crust is in the west Pacific and north-west Atlantic — both are about up to 180-200 million years old. However, parts of the eastern Mediterranean Sea could be remnants of the much older Tethys Ocean , at about 270 and up to 340 million years old.
Here, we highlight key findings that reveal the architecture of oceanic crust and the thermal, physical, and chemical processes that are responsible for the growth and structure of the oceanic lithosphere.
