What are Archean greenstone belts?
Archaean greenstone belts and associated granitic rocks comprise some of the most diverse rock types on the Earth’s surface and were formed during the early stages of the development of the planet from Eoarchaean to Neoarchaean times – a period extending back from about 4000 to 2500 million years ago.
Where is the Yilgarn Craton?
Western Australia
The Archaean Yilgarn Craton in the southern half of Western Australia covers an area of ~650 000 km2. It is bounded to the south and SE by the Mesoproterozoic Albany-Fraser Orogen, to the north by the Palaeoproterozoic Capricorn Orogen, and to the west by the Mesozoic Perth Basin.
Why is the Yilgarn Craton important?
It provides an analysis of regolith geology investigations that were conducted in many districts of contrasting contemporary geomorphic and climatic conditions. The Yilgarn Craton is composed of Archaean rocks, predominantly granitoids, that are crossed by north‐northwest‐trending belts of greenstones.
How was Yilgarn Craton formed?
The Yilgarn Craton appears to have been assembled between ~2.94 and 2.63 Ga by the accretion of a multitude of formerly present blocks or terranes of existing continental crust, most of which formed between 3.2 Ga and 2.8 Ga.
Why are greenstone belts Archean?
Greenstone belts have been interpreted as having formed at ancient oceanic spreading centers and island arc terranes. Greenstone belts are primarily formed of volcanic rocks, dominated by basalt, with minor sedimentary rocks inter-leaving the volcanic formations.
What is the significance of greenstone belts?
greenstone belt Greenstone belts are considered to represent ancient volcano—sedimentary basins bordered and intruded by granitic plutons. These formations represent an important phase of crustal evolution and currently it is commonly considered that they are remnants of back-arc basins.
How old is the Yilgarn Craton?
The Yilgarn, Pilbara and Kimberley cratons of Western Australia contain rocks more than 2.5 billion years old. Kalgoorlie is situated in the eastern part of the Yilgarn Craton (‘Yilgarn’ is a word used by Aboriginal people in the area of Southern Cross to describe quartz).
How were greenstone belts formed?
When were greenstone belts formed?
about 1.5 billion years ago
exposed along what are called greenstone belts. The basement of the Angaran platform was largely formed by about 1.5 billion years ago.
What is an Archean craton?
Abstract. Archaean cratons are the stable remnants of Earth’s early continental lithosphere, and their structure, composition and survival over geological time make them unique features of the Earth’s surface.
What is Yilgarn?
What is the significance of greenstone belt?
Where was the greenstone belt located?
Introduction. The Isua greenstone belt is located within a part of the Archaean gneiss complex of West Greenland (Bridgwater et al., 1976) that contains remnants of early Archaean tonalitic gneisses (Fig. 2.2-1).
How are Archean cratons formed?
Jordan proposed that cratons formed from a high degree of partial melting of the upper mantle, with 30 to 40 percent of the source rock entering the melt. Such a high degree of melting was possible because of the high mantle temperatures of the Archean.
What is greenstone belts made of?
A greenstone belt is a usually an elongate structure composed dominantly of metamorphosed volcanic and sedimentary rocks that, together with granitoids and gneiss, are the constituents of Archean and Proterozoic cratons.
What is the Yilgarn Block?
Yilgarn Block (Yilgarnia) The Yilgarn Block in Western Australia is one of the most ancient landscapes preserved anywhere on Earth. The Yilgarn Plateau is a craton, one of the original masses of rock that rose out of the sea in the Late Archaean, about 2700 ma to form the original landmass of Australia.