地质论评2013，Vol.59Issue(2)：225-233,9.
西藏班公湖岛弧带晚白垩世地壳伸展期间碳的壳内循环
The Crustal Carbon Cycling in the Late Cretaceous Extension of Bangong Lake Arc Zone in the Xizang (Tibetan) Plateau
摘要
Abstract
Magnesian carbonatite rocks in the Bangong Lake area are due to the crustal carbon cycling under the influence of magma and fluids in the process of Qinghai-Tibet plateau uplift. LA-MC-ICP-MS U-Pb isotope dating of metasomatic zircons from the magnesian carbonatites shows that the weighted average age is 80. 3 ± 1. 2 Ma (MSWD =3. 8). The results explain that metasomatic magnesian carbonatite was formed in Late Cretaceous, and was related to the activities of contemporary acid rock wall in this area. C and 0 isotope determinations of magnesite and siderite show δ13CV.PDB values ranges from 0. 9%e to 1.6%e, averagely 1. 25%c, and δ18 OV.SMOW values ranges from 15. 9%o to 21.7%e, averagely 18. 65%c, indicatings that the carbon was derived from the marine carbonate rocks in the surrounding rock. The carbon cycle conditions reveal that a lot of fluid as the carrier came from meteoric water, and circulating temperature was evaluated between 300 ~ 350℃ from the 100 m to 2. lkm underground. The slack tectonic setting in late Cretaceous contribute to magma upwelling and infiltration of meteoric water. More importantly, it provides an available driver to speed up the emissions of CO2, and carbon circulation in the crust.关键词
碳循环/镁质碳酸岩体/LA-MC-ICP-MS测年/同位素/西藏/班公湖Key words
carbon circulation/ magnesian carbonatite/ LA-MC-ICP-MS/ isotope/ Xizang ( Tibetan) plateau/ Bangong Lake引用本文复制引用
宋扬,曲晓明,辛洪波,王志云,杜德道..西藏班公湖岛弧带晚白垩世地壳伸展期间碳的壳内循环[J].地质论评,2013,59(2):225-233,9.基金项目
本文为国家重大基础研究发展计划项目(编号2011CB403103)、国家"十一五"科技支撑计划项目(编号2006BAB01A05)和中国地质调查局青藏专项(编号1212010818097)的成果. （编号2011CB403103）
