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The result is a distinct boundary of very fine grain igneous rock along the border of the country rock. [3] The surrounding rock may be "baked" through contact metamorphism, resulting in non-foliated metamorphic rocks. [1] Rocks that were originally limestone, quartz sandstone, and shale become marble, quartzite, and hornfels, respectively.
Contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained [46] [47] and extremely tough. [48] The Yule Marble used on the Lincoln Memorial exterior and the Tomb of the Unknown Soldier in Arlington National Cemetery was formed by contact ...
This kind of regional metamorphism is known as burial metamorphism. This tends to produce low-grade metamorphic rock. [29] Much more common is metamorphic rock formed during the collision process itself. [30] The collision of plates causes high temperatures, pressures and deformation in the rocks along these belts. [31]
The sanidinite facies is a rare facies of extremely high temperatures and low pressure. It can only be reached under certain contact-metamorphic circumstances. Due to the high temperature the rock experiences partial melting and glass is formed. This facies is named for the mineral sanidine. It is characterized by the following mineral assemblages:
A sample of banded hornfels, formed by contact metamorphism of sandstones and shales by a granite intrusion. Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. [1]
In contact metamorphism (metamorphism caused by high temperatures at low pressure in the vicinity of an igneous intrusion) a local contact aureole of zones is formed around a heat source. In rocks in subduction zones, that are transported to great depths in relatively low temperatures, rare types of metamorphic zones can develop. Two facies ...
These rocks are fine-grained and sometimes cool so rapidly that no crystals can form and result in a natural glass, such as obsidian, however the most common fine-grained rock would be known as basalt. Any of the three main types of rocks (igneous, sedimentary, and metamorphic rocks) can melt into magma and cool into igneous rocks.
Metamorphic rocks are formed by subjecting any rock type—sedimentary rock, igneous rock or another older metamorphic rock—to different temperature and pressure conditions than those in which the original rock was formed. This process is called metamorphism, meaning to "change in form". The result is a profound change in physical properties ...