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Gabbro specimen Photomicrograph of a thin section of gabbro. Gabbro (/ ˈ ɡ æ b r oʊ / GAB-roh) is a phaneritic (coarse-grained and magnesium- and iron-rich), mafic intrusive igneous rock formed from the slow cooling magma into a holocrystalline mass deep beneath the Earth's surface.
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
Diabase (/ ˈ d aɪ. ə ˌ b eɪ s /), also called dolerite (/ ˈ d ɒ l. ə ˌ r aɪ t /) or microgabbro, [1] is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained to aphanitic chilled margins which may ...
The cumulate rock is a plagioclase-pyroxene cumulate (a gabbro) and the melt is now more felsic and aluminous in composition (trending towards andesite compositions). In the above example, the plagioclase and pyroxene need not be pure end-member compositions (anorthite-enstatite), and thus the effect of depletion of elements can be complex.
Examples of phaneritic igneous rocks are gabbro, diorite, and granite. Porphyritic textures develop when conditions during the cooling of magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a ...
Types of trap rock include basalt, peridotite, diabase, and gabbro. [1] Trap is also used to refer to flood (plateau) basalts , such as the Deccan Traps and Siberian Traps . [ 2 ] The erosion of trap rock created by the stacking of successive lava flows often creates a distinct stairstep landscape from which the term trap was derived from the ...
The principal difference between norite and gabbro is the type of pyroxene of which it is composed. Norite is predominantly composed of orthopyroxenes, largely high-magnesian enstatite or an iron-bearing hypersthene. The principal pyroxenes in gabbro are clinopyroxenes, generally iron-rich augites. [2] [3]
Diorite is an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and sometimes pyroxene.The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite.