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[54] [55] [1] Before the mid-1970s, geologists utilized the metamorphic facies classification to investigate metamorphic rocks and determined their P-T characteristics. [1] However, little was known about the evolutionary processes of these P-T conditions and how metamorphic rocks reach the surface at that time.
Metamorphic rocks are formed when existing rock is transformed physically or chemically at elevated temperature, without actually melting to any great degree. The importance of heating in the formation of metamorphic rock was first noted by the pioneering Scottish naturalist, James Hutton, who is often described as the father of modern geology ...
[1] Monazite geochronology is a dating technique to study geological history using the mineral monazite. It is a powerful tool in studying the complex history of metamorphic rocks particularly, as well as igneous, sedimentary and hydrothermal rocks. [2] [3] The dating uses the radioactive processes in monazite as a clock.
The Tetons and other north-central ranges contain folded and faulted rocks of Paleozoic and Mesozoic age draped above cores of Proterozoic and Archean igneous and metamorphic rocks ranging in age from 1.2 billion (e.g., Tetons) to more than 3.3 billion years (Beartooth Mountains). [16]
The prominent black diabase dike on Mount Moran is representative of similar dikes formed about 1.3 billion years ago. Sometime around 2.5 billion years ago, blobs of magma intruded into the older rock, forming plutons of granitic rock. [3] Extensive exposures of this rock are found in the central part of the range.
The oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon, which is defined to start with the formation of the oldest intact rocks on Earth.
[33] [34] Subsequent erosion of the mountains exposes the roots of the orogenic belt as extensive outcrops of metamorphic rock, [35] characteristic of mountain chains. [33] Metamorphic rock formed in these settings tends to shown well-developed foliation. [33] Foliation develops when a rock is being shortened along one axis during metamorphism.
In Greenland the rock was formed by two consecutive metamorphic overprints of an originally igneous rock. [3] The intrusion took place in the Archean around 2800 million years ago and the metamorphic overprint was dated at 2700 and 2500 million years ago.