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Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside. [ 1 ] This texture is common in aphanitic , or glassy, igneous rocks that have come to the surface of the Earth, a process known as extrusion .
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. [ 1 ] [ 2 ] It is typically dark in color (brown, black or purplish-red), and basaltic or andesitic in composition.
Basalt (UK: / ˈ b æ s ɒ l t,-ɔː l t,-əl t /; [1] [2] US: / b ə ˈ s ɔː l t, ˈ b eɪ s ɔː l t /) [3] is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon.
Basalt is a very common volcanic rock with low silica content. Rhyolite is a volcanic rock with high silica content. Rhyolite has silica content similar to that of granite while basalt is compositionally equal to gabbro. Intermediate volcanic rocks include andesite, dacite, trachyte, and latite. [citation needed]
The basement rock of the Marsili Basin is vesicular basalt. [6] Due to the abundance (10–30% of rock volume) and size (up to 3 or 4 mm) of the vesicles, it is likely that the basalt was emplaced as a flow rather than a sill. Overlaying the basement is 250 meters of calcareous mud and ooze with interbedded volcanoclastic layers.
Zeolites are microporous silicate minerals that can be produced by the reaction of pore fluids with basalt and pelagic sediments. The zeolite facies conditions typically only affect pelitic sediments undergoing burial, but is commonly displayed by the production of zeolite minerals within the vesicles of vesicular basalt.
The vesicular and massive basalts occur in alternating bands, with the vesicular bands usually being the top and base of each flow. [ 10 ] [ 12 ] The basalt mineralogy consists of mainly of plagioclase , augite , magnetite , some ilmenite and volcanic glass .
Flaked stone artefacts from Australia, made of tachylite. A second mode of occurrence of tachylite is in the form of lava flows.Basaltic rocks often contain a small amount of glassy ground-mass, and in the limburgites this becomes more important and conspicuous, but vitreous types are far less common in these than in the acid lavas.