Precambrian Large Igneous Provinces: An Overview of Geochronology, Origins and Impact on Earth Evolution

摘要

Precambrian large igneous provinces flourished during the Proterozoic and some, such as the 1 27 Ga Mackenzie event in North America, resemble their Phanerozoic counterparts with good evidence for the production of large volumes of mafic magma in short periods of geologic time (<10 m y), a specific focus of this magmatism, and regional uplift prior to the onset of volcanism In many Precambrian examples, the flood basalts have been largely removed by erosion and only the root zone (eg,, dyke swarm, layered mafic intrusion) of these large igneous provinces is preserved. The short duration of this magmatism and the geometric relationship between linear dyke swarms and basement geology can potentially provide a robust geological pin in continental reconstructions The extensive 2 37 Ga E-W trending Bangalore dyke swarm in the Dharwar craton, India cross-cuts N-S trending Neoarchean greenstone belts and the 2 51 Ga Closepet granite and is a good example of the potential for providing a cornerstone in Paleoproterozoic continent reconstruction In contrast, the 1 89 Ga Southern Bastar-Cuddapah large igneous province in southern India is one of several large igneous provinces formed at this time on different continents, including the 1,89-1 88 Ga cireum-Superior mafic/ultramafic magmatism in North America and the 1.88-1.87 Ga Waterberg Group sills in South Africa, and is part of a global period of enhanced mantle melting, A challenge for future attempts at Precambrian continent reconstruction is to distinguish between discrete global periods of enhanced mantle melting and a single specific focus large igneous province.