Tectonic implications of the Nan suture zone and its relationship to the Sukhothai Fold Belt, northern Thailand
Singharajwarapan, S and Berry, RF, Tectonic implications of the Nan suture zone and its relationship to the Sukhothai Fold Belt, northern Thailand, Journal of Asian Earth Sciences, 18, (6) pp. 663-673. ISSN 1367-9120 (2000) [Refereed Article]
The Nan Suture and the Sukhothai Fold Belt reflect the processes associated with the collision between the Shan-Thai and Indochina Terranes in southeast Asia. The Shan-Thai Terrane rifted from Gondwana in the Early Permian. As it drifted north a subduction complex developed along its northern margin. The Nan serpentinitic melange is a thrust slice within the Pha Som Metamorphic Complex and in total this unit is a Late Permian accretionary complex containing offscraped blocks from subducted oceanic crust of Carboniferous and Permian age. The deformational style within the Pha Som Metamorphic Complex supports a west-dipping subduction zone. The Late Permian to Late Triassic fore-arc basin sediments are preserved in the Sukhothai Fold Belt and include a near continuous sedimentary record, at least locally. The whole sequence was folded and complexly thrust in the Late Triassic as a result of the collision. Late syn- to post-kinematic granites place an upper limit of 200 Ma on the time of collision. Post-orogenic sediments prograded across the suture in the Jurassic. (C) 2000 Elsevier Science Ltd. All rights reserved.