Tectonic development of early Precambrian orogens
A review of recent literature shows that Archaean and Early Proterozoic orogens developed by tectonic processes that were largely comparable to those in operation today. During the Archaean the earliest crust segregated from the mantle, and greenstone belts largely formed as accretionary collages of...
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| Format: | Report |
| Language: | English |
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Department of Geology, Leiceter University
1998
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| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2336 http://id.nii.ac.jp/1291/00002336/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2336&item_no=1&attribute_id=18&file_no=1 |
| Summary: | A review of recent literature shows that Archaean and Early Proterozoic orogens developed by tectonic processes that were largely comparable to those in operation today. During the Archaean the earliest crust segregated from the mantle, and greenstone belts largely formed as accretionary collages of oceanic crust, island arcs, accretionary prisms, and possible plateaus. Calcalkaline magma genesis was controlled by slab melting without dehydration leading to common tonalite-trondhjemite-granodiorite suites, which are widely preserved today in Archaean granulite-gneiss belts. Rapid crustal growth and coalescence of terranes in the late Archaean led to formation of one or more supercontinents at ca. 2.5 Ga, the breakup of which gave rise to extensive passive continental margins and shelf sequences in the Early Proterozoic. The widespread development by subduction processes of island arcs and of magmatic arcs in active continental margins aids in demarcating Early Proterozoic suture zones within accretionary and collisional orogens which are comparable with those of the present-day. |
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