Petrogenesis of Indosinian Granitoids in Middle-Segment of South Qinling Tectonic Belt：Constraints from Sr-Nd Isotopic Systematics

• Published in: Acta geologica Sinica (Beijing) Vol. 85; no. 3; pp. 610 - 628
• Main Authors: LIU, Shuwen, LI, Qiugen, TIAN, Wei, WANG, Zongqi, YANG, Pengtao, WANG, Wei, BAI, Xiang, GUO, Rongrong
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2011; Wiley Subscription Services, Inc; Key Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education, Peking University, Beijing,100871, China%Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
• Edition: English ed.
• Subjects: early Mesozoic tectonic backgrounds; Geochemistry; Indonisian granitoids; Magma; Nd同位素; Petrochemistry; petrogenesis; South Qinling tectonic belt; Sr-Nd isotopic systematics; 中间段; 印支期花岗岩; 同位素体系; 岩浆来源; 成因; 秦岭构造带; 秦岭造山带; Sr-Nd isotopic systematics; petrogenesis; Petrochemistry; Indonisian granitoids; South Qinling tectonic belt; early Mesozoic tectonic backgrounds
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/j.1755-6724.2011.00455.x

South Qinling Tectonic Belt（SQTB）is located between the Shangzhou-Danfeng and Mianxian-Lueyang sutures.There are a lot of early Mesozoic granitoid plutons in its middle segment, comprising the Dongjiangkou-Zhashui granitoid plutons at the northeast,Huayang-Wulong-Laocheng granitoid plutons at the central part,Xiba granitoid pluton at the northwest and Guangtoushan-Liuba granitoid plutons at the southwest.These Indonisian granitoids contain a mass of various scale mafic enclaves,which show sometimes clear boundaries and sometimes transitional boundaries with their host granitoids.These granitoids also exhibit metaluminous to peraluminous series,commonly higher Mg# and a wide range of petrochemistry from low-K tholeiite series,through mid-K and high-K calc-alkaline series to shoshonite series and predominated samples are attributed to mid-K and high-K calc-alkaline series.Detailed analyses in Sr-Nd isotopic systematics and petrochemistry reveal that there may be regionally initial granitoid magma of the Indonisian granitoid plutons,comprising Dongjiangkou-Zhashui,Huayang-Wulong-Laocheng,Xiba,and Guangtoushan-Liuba granitoid plutons,which were produced by hybrids of magmas in various degrees,and the initial magmas were derived from both the mantle and the lower continental crust（LCC）sources in the SQTB.The initial granitoid magma further did the magma hybrid with the magmas from the LCC,crystallization fractionation,and assimilation with upper crustal materials during their emplacement to produce these granitoid plutons in the SQTB.These magmatism processes are most likely to occur under continent marginal arc and syn-collision to post-collision tectonic backgrounds.