the rock picture below is a dark magic igneous rock most of this rock is compose
ID: 158472 • Letter: T
Question
the rock picture below is a dark magic igneous rock most of this rock is composed of tiny crystals but there are some much larger yellow green olive igneous mineral
by using texture (aphantic ,phaneritic,pyroclastic etc) and composition (Felsic: quartz, potassium feldspar,/ mafic has pyroxene,Olivine, plagioclase feldspar minerals)
what type of igneous rock is in the picture? and how did it formed it's magmatic history where did magma come from and how was it formed how the magma travelled and cooled into solid rock. provide evidences
Explanation / Answer
Answer:
Igneous rock is in the picture is SERPENTINITE
Formation of Serpentine: It is formed by the metamorphism of Peridotite, or the minerals in peridotite such as olivine. Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization.Serpentinization is a geological low-temperature metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized and hydrolyzed with water into serpentinite. Peridotite, including dunite, at and near the seafloor and in mountain belts is converted to serpentine, brucite, magnetite, and other minerals. In the process large amounts of water are absorbed into the rock increasing the volume and destroying the structure.
from mid-ocean ridges, drilling into the magma-poor passive margins of Newfoundland-Iberia demonstrates that carbonate-serpentinite associations build up the interface between tectonically exhumed serpentinized mantle and the post-rift sedimentary cover (e.g., Tucholke and Sibuet, 2007). However, the mass fraction of carbonates and serpentinites that formed during exposure on the seafloor, relative to the mass fraction that formed later under a thick pile of post-rift sediments, is poorly constrained.
Serpentinite is formed from olivine via several reactions, some of which are complementary. Olivine is a solid solution between themagnesium-endmember forsterite and the iron-endmember fayalite. Serpentinite reactions 1a and 1b, below, exchange silica between forsterite and fayalite to form serpentine group minerals and magnetite. These are highly exothermic reactions.
Reaction 1a:
Fayalite + water magnetite + aqueous silica + hydrogen
3Fe2SiO4 + 2H2O 2Fe3O4 + 3SiO2 + 2H2
Reaction 1b:
Forsterite + aqueous silica serpentine
3Mg2SiO4 + SiO2 + 4H2O 2Mg3Si2O5(OH)4
Reaction 1c:
Forsterite + water serpentine + brucite
2Mg2SiO4 + 3H2O Mg3Si2O5(OH)4 + Mg(OH)2
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