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The Precambrian could be divided into five "natural" eons, characterized as follows: [47] Accretion and differentiation: a period of planetary formation until giant Moon-forming impact event. Hadean: dominated by heavy bombardment from about 4.51 Ga (possibly including a cool early Earth period) to the end of the Late Heavy Bombardment period.
The Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 539 Ma).It includes the first three of the four eons of Earth's prehistory (the Hadean, Archean and Proterozoic) and precedes the Phanerozoic eon.
The Grouse Creek block is a Precambrian basement province of 2.45 to 2.70 billion year old orthogneisses. [ 2 ] [ 3 ] The Grouse Creek block is one of several Proterozoic and Archean accreted terranes that lie to the north and west of the Wyoming craton , including the Farmington Canyon Complex (<2.5 Ga ), the Selway terrane (2.4-1.6 Ga), the ...
The Precambrian basement of Wyoming consists mainly of three major geologic terranes, the Archean Wyoming Craton or Province, the Paleoproterozoic Trans-Hudson orogen, and the Paleoproterozoic Colorado orogeny. The Colorado orogen collided with the Wyoming Craton at 1.78–1.75 Ga. Collision of the Colorado orogen and the Trans-Hudson orogen ...
Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. [4] [5] [6] Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with ...
The majority of continental crust on the planet is around 1 to 3 billion years old, and it is theorised that there was at least one period of rapid expansion and accretion to the continents during the Precambrian. Much of the basement rock may have originally been oceanic crust, but it was highly metamorphosed and converted into continental crust.
According to evidence from radiometric dating and other sources, Earth formed about 4.54 billion years ago. [7] [8] [9] The current dominant theory of planet formation suggests that planets such as Earth form in about 50 to 100 million years but more recently proposed alternative processes and timescales have stimulated ongoing debate in the planetary science community. [10]
The earliest geological units found in the Western Block are formed in Neoarchean, [8] when the major crustal accretion and reworking took place. [10] The Neoarchean rocks in the Precambrian basement are mainly composed of greenstones, high-grade metamorphic rocks and granitoids. [16]