Search results
Results from the WOW.Com Content Network
The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class. [9] Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava.
Gabbro (/ ˈɡæbroʊ / 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. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt.
Dike (geology) A magmatic dike (vertical) cross-cutting horizontal layers of sedimentary rock, in Makhtesh Ramon, Israel. In geology, a dike or dyke is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies ...
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 ...
The tholeiitic magma series (/ ˌθoʊliˈaɪtɪk /) is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic ...
Model of the crystallization of a subsurface magma chamber. The Skaergaard intrusion was formed 56 million years ago during the opening of the North Atlantic Ocean. [1] The intrusion was emplaced beneath the preexisting rock in the region, including plateau basalt and gneiss. [1][2] The intrusion has a general oval shape, which is atypical in ...
Mechanism of formation. Bimodal volcanism is normally explained as a result of partial melting of the crust, creating granitic magmas, during the emplacement of large volumes of relatively hot basaltic magma from a mantle source. The two magma types then form separate magma chambers giving rise to periodic eruption of both types of lava. [7][8]
The magmas that produce ultrapotassic rocks are produced by a variety of mechanisms and from a variety of sources, but generally occur in a heterogenous, anomalous, phlogopite-bearing upper mantle. [2] The following conditions are favorable for the formation of ultrapotassic magmas. [3] partial melting at a great depth; low degrees of partial ...