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On Granitic Tectono-Magmatic Assemblages

WANG De-zi,SHU Liang-shu   

  1. Department of Earth Sciences, Nanjing University, Nanjing 210093, China
  • Received:2007-09-20 Revised:2007-09-20 Online:2007-09-20 Published:2007-09-20

Abstract: Granitic tectono-magmatic assemblages mainly reflect the genetic connections between the magma types of granites and tectonic environments. Viewing from the global scope, particularly looking at the situation in China,the granitic tectono-magmatic assemblages could be divided into five major types: (1) oceanic crust subduction type, such as continental margins on both sides of the Pacific Ocean; (2) continent continent collision type, e.g., the Himalaya-Gangdise collisional belt; (3) extensional continental margin type, such as the Southeast China extensional margin and the Basin and Range Province, USA; (4) inland faulted depression type, such as the Lower Yangtze faulted depression and the Qiantan-Xinjiang faulted depression; (5) rift type, such as the Eastern African Rift and the Panxi Rift of China. By calculating the calc-alkali index (CA) and alumina saturation index (ASI), the magma types of the granites can be roughly determined. The temporal and spatial evolution of orogenic granitic belt shows certain kind of regularities: subduction type granites → collision type granites → extensional type granites. Or, it may be described as: precollision granites → syncollision granites → postcollision granites. However, instead of giving general assumptions, we should carefully examine and analyze actual cases and conditions before reaching a conclusion.