Search results
Results from the WOW.Com Content Network
Metamorphic rock can be formed locally when rock is heated by the intrusion of hot molten rock called magma from the Earth's interior. The study of metamorphic rocks (now exposed at the Earth's surface following erosion and uplift) provides information about the temperatures and pressures that occur at great depths within the Earth's crust.
The history of alteration and metamorphism in the Nuvvuagittuq Greenstone Belt remains poorly understood in many regards. However, attempts have been made to constrain the history using structural techniques, [1] and geochronometric [3] high-pressure deformation is evident throughout the belt as one of the earliest periods of deformation. [1]
The belt contains variably metamorphosed mafic volcanic and sedimentary rocks, and is the largest exposure of Eoarchaean supracrustal rocks on Earth. [3] Due to its age and low metamorphic grade [ 4 ] relative to many Eoarchaean rocks, the Isua Greenstone Belt has become a focus for investigations on the emergence of life [ 5 ] [ 6 ] and the ...
Metamorphism of crustal rocks in which peak temperature exceeds 900 °C, recognized either by robust thermobarometry or by the presence of a diagnostic mineral assemblage in an appropriate bulk composition and oxidation state, such as assemblages with orthopyroxene + sillimanite + quartz, sapphirine + quartz or spinel + quartz, generally at pressure conditions of sillimanite stability in ...
Impactite is rock created or modified by one or more impacts of a meteorite. [1] [2] Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact. [3] On Earth, impactites consist primarily of modified terrestrial material, sometimes with pieces of the original meteorite. [3]
Eoarchean geology is the study of the oldest preserved crustal fragments of Earth during the Eoarchean era from 4.031 to 3.6 billion years ago. Major well-preserved rock units dated to this era are known from three localities, the Isua Greenstone Belt in Southwest Greenland, the Acasta Gneiss in the Slave Craton in Canada, and the Nuvvuagittuq Greenstone Belt in the eastern coast of Hudson Bay ...
Hornfels – Group of metamorphic rocks Calcflinta – A type of hornfels found in the Scottish Highlands; Litchfieldite – Nepheline syenite gneiss; Marble – Type of metamorphic rock – a metamorphosed limestone; Migmatite – Mixture of metamorphic rock and igneous rock; Mylonite – Metamorphic rock – A metamorphic rock formed by shearing
The rock is greasy-looking with annealed quartz and feldspar, and syn-granulite facies leucosomes cutting across metamorphic banding, and subsequently deformed by later metamorphism. The Dugel Gneiss is considered to be intruded into the older Meeberrie Gneiss, possibly as sheets or sills , but most contacts are overprinted by ductile ...