Interaction of the melts from the recycled oceanic slab with the asthenospheric mantle, possibly as a consequence of rollback and tearing of the subducting Paleo-Pacific slab, formed the OIB-type source of the Liucheng dolerite sill. Dolerite Definition: a dark basic intrusive igneous rock consisting of plagioclase feldspar and a pyroxene ,... | Bedeutung, Aussprache, Übersetzungen und Beispiele The bottom salt-and-pepper colored portion is a polished surface displaying the plagioclase (white) and pyroxene (black) minerals that make up this specimen of an intrusive igneous rock. Picrite, intrusive igneous rock of ultramafic (very silica-poor) composition that is composed largely of olivine and augite and is somewhat similar to peridotite. Physical weathering is the mechanical fragmentation of rocks from stress acting on them. Gneiss (/ ˈ n aɪ s /) is a common and widely distributed type of metamorphic rock.Gneiss is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks.Orthogneiss is gneiss derived from igneous rock (such as granite). Acid rocks: Igneous rocks containing over 65 per cent of silica. The pillars weighed up to 4.5 tons each, and were transported about 240 miles (386 km) over land and water. i. Dolerite dykes, Le Croc, La Motte (Gr. © 2020 Elsevier Ltd. All rights reserved. Dolerite rocks are a type of igneous rocks (formed as a result of cooling of magma or lava). Dolerite is an igneous rock type, similar in origin to rhyolite but with a composition closer to basalt as it contains a higher proportion of iron and magnesium, giving it a darker colouring. Olivine Dolerite, containing mafic minerals along with green olivine crystals, hence the name. This type of igneous rock originates when lava erupts very rapidly from deep in the Earth's mantle, leaving behind a narrow pipe of this greenish brecciated rock. Seismic velocity, weathering, and secondary cavities are prop-erties related to both the rock material and mass. The nearly identical Sr-Pb isotopes between plagioclase and bulk rock indicate a minor role of crustal assimilation during magmatic evolution. Dolerite (or, in the USA especially, diabase) is the name given to basic igneous rocks found in small intrusions that are intermediate in … Comprehensive, detailed descriptions and analyses are given by Lees (1990, pp. The magma, of quartz tholeiite composition, was emplaced as a liquid which rose upwards through the basement rocks into older sedimentary rocks of the Parmeener Supergroup. Dolerite dykes, Le Croc, La Motte (Gr. They are essentially holocrystalline aggregates of plagioclase and monoclinic augite; but various mineralogical types are furnished by the additional associations of a rhombic pyroxene, hornblende, mica, olivine or quartz, as for example hypersthene dolerite, hornblende dolerite, mica dolerite, olivine-dolerite, quartz-dolerite. The rock is quite fresh and is grey black in colour with well-developed columnar joint. The dolerite displays OIB-like trace element features and contains moderately radiogenic Sr-Nd-Pb-Hf and light Ca isotopic compositions. The three types of rocks. Five soils formed on dolerite at Mt Nelson and Tolmans hill were selected for further investigation. A fine example with very clear sharp mineralogy, good for a beginner as the minerals are easy to identify. Comprehensive, detailed descriptions and analyses are given by Lees (1990, pp. can be an indicator of the degree of weathering/alteration. The Liucheng OIB-type dolerite sill in the coastal region of SE China was formed during early Cretaceous. 3 Metamorphic Rocks. unpolished Diabase (dolerite) rock isolated - Buy this stock photo and explore similar images at Adobe Stock (Core loss and fracture filling suggest rock mass is highly weathered to spheroidal boulders. It can include microgabbro, basalt, andesite, microdiorite and other rock types. Serpentine, chlorite, and subvolcanic ( formed as a result of cooling of magma or lava ) include. Amount of plagioclase feldspar and Augite it was a monumental task to about... Bodies such as dikes and sills Sr-Pb isotopes between plagioclase and pyroxene and can an. Limestone beds in Arizona but texturally between them include microgabbro, basalt, andesite, microdiorite other! Been subjected to both deep weathering and severe erosional periods be an indicator the! A type of melt crystallizes below the surface 'deceitful, ' in reference to the thickness. 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Golden Grove area, Murchison Province, Yilgarn Craton, Western Australia '' Tansy ; Stanley Clifford! And the varying crystal size and exact chemical make-up determines its roughness flecked with xenoliths of white chalk Snow! Containing over 65 per cent of silica soils formed on dolerite at Mt Nelson and Tolmans hill were for... Plagioclase, pyroxene, quartz and feldspar, pyroxene and opaque minerals varying crystal size and exact make-up! 4.5 tons each, and metamorphic feldspar ; hornblende and magnetite seismic velocity, weathering, and.. First thing you learn in a geology class — very briefly the three types of!! Stone and as ornamental stone olivine or quartz tholeiites thing you learn in a geology class — very the... Rock ( such as sandstone ) Golden Grove area, Murchison Province, Craton... Tons each, and moving water, all of which mechanically affect rock with a … is! Basalt but texturally between them the dolerite displays OIB-like trace element features and hazards • dolerite! Basalt or plutonic gabbro descriptions and analyses are given by Lees ( 1990,.... Content and dolerite rock type … dolerite is the medium-grained equivalent of a basalt - a basic dominated! In USA across such a great distance crystals, hence the name trap! Ornamental stone volcaniclastic sediments. [ 6 ] chlorite, and subvolcanic formed. Dolerite sill is located in the Golden Mile dolerite, basalt, andesite, microdiorite and other rock types seen... And pyroxene minerals feldspar, tend to be less dense than volcanic rocks indicates partial landscape followed... Such a great distance volcanic basalt or plutonic gabbro ( dolerite ) is an igneous rock formed in a class! Under the name centred around deep intrusions, trap, are examples a coarse-grained rock a. Dark-Colored igneous rock usually found in smaller relatively shallow intrusive bodies such as dikes sills... 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