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This piece of mantle can be identified using seismic velocity imaging as well as earthquake maps. [1] Subducting oceanic slabs carry large amounts of water; this water lowers the melting temperature of the above mantle wedge. [2] Melting of the mantle wedge can also be contributed to depressurization due to the flow in the wedge.
The temperature of the mantle increases rapidly in the thermal boundary layers at the top and bottom of the mantle, and increases gradually through the interior of the mantle. [22] Although the higher temperatures far exceed the melting points of the mantle rocks at the surface (about 1,500 K (1,200 °C; 2,200 °F) for representative peridotite ...
The source of obsidian for cultures inhabiting the territory of and around Greece was the island of Milos; the Starčevo–Körös–Criș culture obtained obsidian from sources in Hungary and Slovakia, while the Cardium-Impresso cultural complex acquired obsidian from the island outcrops of the central Mediterranean.
Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as ...
Water carried into the mantle eventually returns to the surface in eruptions at mid-ocean ridges and hotspots. [8] This circulation of water into the mantle and back is known as the deep water cycle or the geologic water cycle. [9] [10] [11] [5] Estimates of the amount of water in the mantle range from 1 ⁄ 4 to 4 times the water in the ocean ...
Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times. [34] Obsidian scalpels have been investigated for use in delicate surgery. [ 35 ] Pumice, also typically of rhyolitic composition, finds important uses as an abrasive , in concrete , [ 36 ] and as a soil amendment . [ 37 ]
The most commonly investigated volatiles are water and carbon dioxide as they are the primary volatiles to drive volcanic and magmatic processes. [4] The absorbance of total water and molecular water is approximately 3450 cm-1 and 1630 cm-1. [2] The peak height of the absorption bands for CO 2 and CO 3 2− are 2350 cm −1 and 1430 cm −1 ...
Earth's outer core is a fluid layer about 2,260 km (1,400 mi) thick, composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. [1] [2] [3] The outer core begins approximately 2,889 km (1,795 mi) beneath Earth's surface at the core-mantle boundary and ends 5,150 km (3,200 mi) beneath Earth's surface at the ...