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Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, [44] the contact aureole, or simply the aureole. [45]
This water lowers the melting point of mantle rock, initiating melting. [5] Understanding the timing and conditions in which these dehydration reactions occur, is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust. [6] Pressure-temperature pathway for subducted crust
Within the upper crust, which is the only part of the Earth's crust geologists can directly sample, metamorphic rock forms only from processes that can occur at shallow depth. These are contact (thermal) metamorphism, dynamic (cataclastic) metamorphism, hydrothermal metamorphism, and impact metamorphism.
Buchan metamorphism occurs often in extensional settings, for example at rift basins. In contact metamorphism (metamorphism caused by high temperatures at low pressure in the vicinity of an igneous intrusion) a local contact aureole of zones is formed around a heat source.
Prograde (pre-peak) metamorphism: the process when the rock is buried and heated in environments such as basins or subduction zones. [3] Devolatilization reactions (release of gases e.g. CO 2, H 2 O) are common. [3] Peak metamorphism: the maximum temperature reached throughout the metamorphic history. [3]
Zeolite facies describes the mineral assemblage resulting from the pressure and temperature conditions of low-grade metamorphism.. The zeolite facies is generally considered to be transitional between diagenetic processes which turn sediments into sedimentary rocks, and prehnite-pumpellyite facies, which is a hallmark of subseafloor alteration of the oceanic crust around mid-ocean ridge ...
A contact can be formed during deposition, by the intrusion of magma, [2] or through faulting or other deformation of rock beds that brings distinct rock bodies into contact. [ 3 ] The geologic subdiscipline of stratigraphy is primarily concerned with depositional contacts, [ 4 ] while faults and shear zones are of particular interest in ...
Running water carries vast amounts of sediment in rivers back to the ocean and inland basins. The accumulated and buried sediments are converted back into rock. A less obvious role of water is in the metamorphism processes that occur in fresh seafloor volcanic rocks as seawater, sometimes heated, flows through the fractures and crevices in the ...