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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 ...
Excessive water present during cooling and quenching of rhyolitic lava causes obsidian to hydrate (i.e., water entering the obsidian glass converts it to perlite). Where perlite is incompletely hydrated, fresh obsidian cores remain as pebbles of marekanite, or Apache tears; this origin has been occasionally described in the geologic literature ...
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 ...
Perlite softens when it reaches temperatures of 850–900 °C (1,560–1,650 °F). Water trapped in the structure of the material vaporises and escapes, and this causes the expansion of the material to 7–16 times its original volume. The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles.
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.
Subduction zone chemistry: The subducted sediments and crust dehydrate and release water-rich fluids into the overlying mantle, causing mantle melting and fractionation of elements between the surface and deep mantle reservoirs, producing island arcs and continental crust. Hot fluids in subduction zones also alter the mineral compositions of ...
Serpentinite is formed from mafic rock that is hydrated by carbon dioxide-deficient sea water that is pressed into the rock at great depths below the ocean floor. [9] This occurs at mid-ocean ridges and in the forearc mantle of subduction zones. [10] [11]
The internal structure of Earth. Earth's mantle is a layer of silicate rock between the crust and the outer core.It has a mass of 4.01 × 10 24 kg (8.84 × 10 24 lb) and makes up 67% of the mass of Earth. [1]