地质通报Issue(2)：274-282,9.
龙木错-双湖古特提斯洋俯冲记录--羌塘中部日湾茶卡早石炭世岛弧火山岩
Early Carboniferous subduction of Lungmu Co-Shuanghu Paleo-Tethys Ocean：Evidence from island arc volcanic rocks in Riwanchaka,Central Qiangtang
摘要
Abstract
Though Lungmu Co-Shuanghu suture experienced the evolution process from early Paleozoic to Triassic, the existing da⁃ta only show that there are numerous collision-related volcanic rocks along this suture in central Qiangtang, whereas information about subduction-related volcanic rocks is very insufficient. To tackle this problem, the authors report the zircon LA-ICPMS U-Pb dating results as well as petrological and whole-rcok geochemical data for andesites from the east side of Riwanchaka in the west part of the Lungmu Co-Shuanghu suture. One sample was dated at 330.6±2.8Ma, suggesting that the Riwanchaka andesites were formed in Early Carboniferous. Volcanic rocks were replaced by silicic fluid and display unstable SiO2 content (54.84%~72.84%) , but all the samples fall in the andesite field in the Nb/Y-Zr/TiO2×0.00001 diagram. Riwanchaka andesites belong to the low to medium-K calc-alkaline series in SiO2-K2O diagram. They are enriched in large-ion lithophile elements such as Rb, Th, U and K, and depleted in high field strength elements such as Nb, Ta and Ti, which are comparable with the characteristics of volcanic arc-related rocks. The Riwanchaka Early Carboniferous andesites in central Qiangtang were eventually emplaced at an island arc setting. The results ob⁃tained by the authors provide geochronologic and petrological evidence for early stage subduction process of Lungmu Co-Shuanghu paleo-Tethys Ocean.关键词
岛弧火山岩/早石炭世/龙木错-双湖结合带/日湾茶卡/羌塘中部/LA-ICP-MS锆石U-Pb年龄Key words
island arc volcanic rocks/Early Carboniferous/Lungmu Co-Shuanghu suture zone/Riwanchaka area/Central Qiang-tang/LA-ICP-MS zircon U-Pb dating分类
天文与地球科学引用本文复制引用
刘函,王保弟,陈莉,李小波,王立全..龙木错-双湖古特提斯洋俯冲记录--羌塘中部日湾茶卡早石炭世岛弧火山岩[J].地质通报,2015,(2):274-282,9.基金项目
国家自然科学青年基金项目(批准号41303028)、四川省基金项目(编号2014JQ0025)和中国地质调查局项目(编号12120114020601、1212011121262) （批准号41303028）
