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Continental and oceanic crust on the upper mantle. Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves.
Continental and oceanic crust on the Earth's upper mantle. Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates.
Earth's crust – Earth's outer shell of rock Continental crust – Layer of rock that forms the continents and continental shelves; Oceanic crust – Uppermost layer of the oceanic portion of a tectonic plate; Earth's mantle – A layer of silicate rock between Earth's crust and its outer core
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.
The thin parts are the oceanic crust, which underlies the ocean basins (5–10 km) and is mafic-rich [9] (dense iron-magnesium silicate mineral or igneous rock). [10] The thicker crust is the continental crust, which is less dense [11] and is felsic-rich (igneous rocks rich in elements that form feldspar and quartz). [12] The rocks of the crust ...
Oceanic crust is denser than continental crust because it has less silicon and more of the heavier elements than continental crust. [11] [12] As a result of this density difference, oceanic crust generally lies below sea level, while continental crust buoyantly projects above sea level. Average oceanic lithosphere is typically 100 km (62 mi ...
A crew towed three large sensors behind a boat, zigzagging across the sea during each trip to hunt for magnetic anomalies — the signatures of magnetic rocks locked in crust that was made by ...
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). Continental crust is subducted with difficulty, but it is subducted to depths of 90–150 km or more, as evidenced by ultra-high ...