四川西部西康群新都桥组碳酸盐岩的锶同位素特征  

Sr Isotopic Characteristics of Carbonate Rocks in Xinduqiao Formation of Xikang Group,Western Sichuan,China

作　　者：曾宜君[1] 黄思静[1] 易同富[2] 郝雪峰[2] 熊昌利[2] 胡作维[1] 

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059 [2]四川省地质调查院,四川成都610081

出　　处：《地球科学与环境学报》2007年第2期126-129,共4页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金项目(40472068);教育部博士点基金项目(20050616005);中国地质调查局地质调查项目(200313000026)

摘　　要：四川西部松潘—甘孜地区广泛分布一套三叠系黑色砂板岩层系,由于其岩性单调、古生物化石贫乏,给该区地层划分、对比带来极大困难。因此,从锶同位素地层学基本原理出发,对甘孜北部西康群新都桥组中薄层状灰岩样品进行了锶同位素组成测定。结果表明,6件样品的N(87Sr)/N(86Sr)分别为0.708688、0.708659、0.708907、0.708223、0.708341、0.708266,平均为0.708514。表明该地层的碳酸盐岩样品可能遭受了不同程度的成岩蚀变,多数样品的锶同位素组成偏离同时代的全球海水锶同位素组成。The Triassic black sandstone-slate from the Xinduqiao Formation of Xikang Group, is widely distributed in the SongparrGanzi region of western Sichuan. Its division and correlation are difficult because of the monotony of lithology and few of fossils, Based on the principle of strontium isotope stratigraphy（SIS）, this paper measured the concentrations of Mn, St, SiO2, and the values of ^87 Sr/^86Sr ratios for the carbonate rocks interbed in the black sandstone-slate of the Xinduqiao Formation, Xikang Group, northern Ganzi. The strontium isotope datum for the carbonate are 0. 708 688, 0. 708 659, 0. 708 907, 0. 708 223, 0. 708 341, 0. 708 266 respectively, with an average of 0. 708 514. The carbonates underwent digenetic alteration in different degrees, leading ^87 Sr/^86Sr ratios of most samples to have some departures to coeval seawater, but some of them contains the information of seawater geochemically. Therefore, the isotope datum can be used to correlate the strata and to calibrate the age of key position of Xinduqiao Formation of Xikang Group.

关 键 词：四川西部 三叠系 西康群 锶同位素 地层学 

分 类 号：P53[天文地球—古生物学与地层学]