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Petrogenesis of Early and Late Paleozoic Plutons in Sanchakou Area of East Tianshan and Their Implications for Evolution of Kangur Suture Zone(PDF)

《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]

Issue:
2015年第05期
Page:
52-70
Research Field:
基础地质与矿产地质
Publishing date:

Info

Title:
Petrogenesis of Early and Late Paleozoic Plutons in Sanchakou Area of East Tianshan and Their Implications for Evolution of Kangur Suture Zone
Author(s):
WANG Chao CHEN Bin MA Xing-hua YAN Xue-long
1. School of Earth and Space Sciences, Peking University, Beijing 100871, China; 2. Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, Peking University, Beijing 100871, China; 3. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, Anhui, China; 4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
Keywords:
granite crust-mantle magma mixing Paleozoic island arc Kangur suture zone tectonic evolution East Tianshan Xinjiang
PACS:
P581
DOI:
-
Abstract:
The petrogenesis and tectonic setting of Sanchakou deposit pluton and East Sanchakou pluton in East Tianshan area were discussed. Sanchakou deposit pluton consists mainly of granodiorite-diorite, and LA-ICP-MS zircon U-Pb dating results indicate that Sanchakou deposit pluton forms at 443 Ma and is the product of Late Ordovician magmatism. This pluton exhibits island arc setting with the characteristics of enrichment in light rare earth element (LREE) and large ion lithophile element (LILE), and depletion in high field strength element (HFSE). High εNd(t) (6.6-7.5) and low initial N(87Sr)/N(86Sr) (0.703 69-0.703 89) suggest that the mafic end-member during magma mixing could have been originated from a young lithospheric mantle source, which is previously metasomatized by subduction zone melts/fluids in Early Paleozoic. Underplating of mantle-derived basaltic magma leads to partial melting of lower crust. Mixing of basaltic magma and the resultant crustal granitic melt forms the intermediate and acid magma. East Sanchakou pluton is mainly made up of granite-granodiorite-diorite, and LA-ICP-MS zircon U-Pb dating results suggest that this pluton is emplaced at about 322 Ma and is the product of post collisional magmatism of Central Asian orogenic belt. This pluton also exhibits island arc setting with the characteristics of enrichment in LREE and LILE, and depletion in HFSE, but the island arc setting characteristics are probably inherited from the lower crust source, which is dominated by Early Paleozoic deep island arc magmatite. This pluton is also formed by the mixing of crustal-mantle magma, and its mafic end-member can be simulated by the homochronous mafic-ultramafic pluton in East Tianshan area. The establishment of volcanic arc magmatic assemblage of Sanchakou deposit pluton shows that the subduction time in Kangur area can date back to Ordovician. Region tectonic transforms extrusion into extension at the early Late Carboniferous, East Sanchakou pluton is corresponding to the stage of regional post-collisional structural evolution.

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Last Update: 2015-09-28