Magmatism during continental collision, subduction, exhumation and mountain collapse in collisional orogenic belts and continental net growth： A perspective

• Published in: Science China. Earth sciences Vol. 58; no. 8; pp. 1284 - 1304
• Main Authors: Song, ShuGuang, Wang, MengJue, Wang, Cao, Niu, YaoLing
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01-08-2015; Springer Nature B.V
• Subjects: Continental crust; Earth and Environmental Science; Earth Sciences; Exhumation; Lithosphere; Magma; Marine; Metamorphic rocks; Mountains; Oceanic crust; Research Paper; Upwelling; 俯冲带; 地壳增厚; 大陆岩石圈; 大陆深俯冲; 大陆碰撞; 山体崩塌; 岩浆活动; 碰撞造山带; collisional orogeny; continental deep subduction; magmatism; continental net growth; orogen unrooting and collapse
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-015-5102-x

Continental orogens on Earth can be classified into accretionary orogen and collisional orogen. Magmatism in orogens occurs in every periods of an orogenic cycle, from oceanic subduction, continental collision to orogenic collapse. Continental collision requires the existence of prior oceanic subduction zone. It is generally assumed that the prerequisite of continental deep sub- duction is oceanic subduction and its drag force to the connecting passive-margin continental lithosphere during continental collision. Continental subduction and collision lead to the thickening and uplift of crust, but the formation time of the related magmatism in orogens depends on the heating mechanism of lithosphere. The accretionary orogens, on the other hand, have no strong continental collision, deep subduction, no large scale of crustal thrusting, thickening and uplift, and no UHP eclo- gite-facies metamorphic rocks related to continental deep subduction. Even though arc crust could be significantly thickened during oceanic subduction, it is still doubtful that syn- or post-collisional magmatism would be generated. In collisional oro- gens, due to continental deep subduction and significant crustal thickening, the UHP metamorphosed oceanic and continental crusts will experience decompression melting during exhumation, generating syn-collisional magmatism. During the orogen unrooting and collapse, post-collisional magmatism develops in response to lithosphere extension and upwelling of astheno- spheric mantle, marking the end of an orogenic cycle. Therefore, magmatism in orogens can occur during the continental deep subduction, exhumation and uplift after detachment of subducted oceanic crust from continental crust, and extensional collapse The time span from continental collision to collapse and erosion of orogens （the end of orogenic cycle） is 50-85 Myr. Colli- sional orogens are the key sites for understanding continental deep subduction, exhumation, uplift and orogenic collapse. Magmatism in collisional orogens plays important roles in continental reworking and net growth.