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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.
Continental crust is also less dense than oceanic crust, whose density is about 2.9 g/cm 3 (0.10 lb/cu in). At 25 to 70 km (16 to 43 mi) in thickness, continental crust is considerably thicker than oceanic crust, which has an average thickness of around 7 to 10 km (4.3 to 6.2 mi).
North China Craton – Continental crustal block in northeast China, Inner Mongolia, the Yellow Sea, and North Korea; Ossa-Morena plate; Piemont-Liguria plate – Former piece of oceanic crust that is seen as part of the Tethys Ocean; Proto-Alps Terrane; Rhenohercynian plate – Fold belt of west and central Europe, formed during the Hercynian ...
The estimated average density of the continental crust is 2.835 g/cm 3, with density increasing with depth from an average of 2.66 g/cm 3 in the uppermost crust to 3.1 g/cm 3 at the base of the crust. [13] In contrast to the continental crust, the oceanic crust is composed predominantly of pillow lava and sheeted dikes with the composition of ...
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 ...
Most areas of oceanic crust show characteristic stripes due to periodic magnetic reversals during formation at a mid-oceanic ridge. The continental crust is by contrast typically magnetically quiet. This method is dependent on stripes being present and will not work for oceanic crust created during the Cretaceous Quiet Zone. On some magma-rich ...
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 ...
When oceanic lithosphere and continental lithosphere collide, the dense oceanic lithosphere subducts beneath the less dense continental lithosphere. An accretionary wedge forms on the continental crust as deep-sea sediments and oceanic crust are scraped from the oceanic plate. Volcanic arcs form on continental lithosphere as the result of ...