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引用本文:谢韬,胡世学,周长勇,张启跃,黄金元,文芠. 云南含罗平生物群层位锶同位素组成与演化[J]. 中国地质, 2019, 46(3): 642-650.
XIE Tao,HU Shixue,ZHOU Changyong,ZHANG Qiyue,HUANG Jinyuan,WEN Wen. Composition and evolution of strontium isotope from the fossiliferous layers of the Luoping biota, Yunnan[J]. Geology in China, 2019, 46(3): 642-650(in Chinese with English abstract).
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云南含罗平生物群层位锶同位素组成与演化
谢韬, 胡世学, 周长勇, 张启跃, 黄金元, 文芠
中国地质调查局成都地质调查中心, 四川 成都 610081
摘要:
现有公布的数据显示,海水87Sr/86Sr值在中三叠世安尼期较为平稳,有别于早三叠世因环境导致的动荡变化,为二叠纪末生物大灭绝之后生物复苏的加速期,而罗平生物群就是该加速期的标志性生物群。本文研究了含罗平生物群层位标准剖面-大凹子剖面上连续沉积的26件碳酸盐岩样品的锶同位素组成与演化,用于了解含罗平生物群层位沉积海水锶同位素的变化趋势。结果显示:(1)碳酸盐岩中Sr平均值大于2000×10-6,主要来自于文石和海洋成岩作用;(2)低Mn和Mn/Sr<0.4说明:87Sr/86Sr数据在很大程度上能代表同时期海水中的87Sr/86Sr比值;(3)这些样品的87Sr/86Sr值变化在0.707969~0.708253,平均值为0.708025,锶同位素比值变化曲线呈小幅度的起伏波动,其值明显大于同时期欧洲等地公布的数据,但同华南其他地区公布的数据具有相似性,推测含罗平生物群层位锶同位素组成仅代表区域事件,受印支运动影响。
关键词:  锶同位素  罗平生物群  安尼期  海相碳酸盐岩  云南
DOI:10.12029/gc20190314
分类号:P597
基金项目:中国地质调查局项目“贵州1:5万兴义县、郑屯、安龙县幅区域地质矿产调查”(12120114068101)“、南盘江成矿区贞丰和富宁地区地质矿产调查”(DD20160020)和国家自然科学基金项目“应用同步加速器X射线层析显微技术重建云南罗平中三叠世牙形石多分子器官”(41502013)联合资助。
Composition and evolution of strontium isotope from the fossiliferous layers of the Luoping biota, Yunnan
XIE Tao, HU Shixue, ZHOU Changyong, ZHANG Qiyue, HUANG Jinyuan, WEN Wen
Chengdu Center of China Geological Survey, Chengdu 610081, Sichuan, China
Abstract:
The 87Sr/86Sr curve of seawater is relatively stable in the Anisian period of Middle Triassic according to data available, which is different from the situation of frequent changes in the Early Triassic. The recovery of marine ecosystem from the endPermian mass extinction experienced an accelerating phase during the Anisian period. The Luoping biota is one of the typical representatives of the Triassic biota. The authors studied the composition and evolution of the strontium isotope in 26 carbonate samples from the standard section, i.e., Dawazi section, of the Luoping biota, in order to know the change of strontium isotope from the fossiliferous layers which contain the Luoping biota. The results show three remarkable characteristics:(1) The average value of Sr is more than 2000×10-6 from the carbonate, which is mainly caused by the aragonite and diagenesis; (2) the low value of Mn and the Mn/Sr ratios less than 0.4 show that the these 87Sr/86Sr ratios can represent the composition of Sr isotope of the coeval seawater; (3) the ratios of 87Sr/86Sr of all samples range between 0.707969 and 0.708253, with the average ratio 0.708025. It is notable that the ratios of the 87Sr/86Sr are larger than the data for the same geological time published from Europe. Nevertheless, they are similar to Sr isotopic values from other areas in southern China. The authors therefore hold that the strontium isotope composition of the fossiliferous layers of the Luoping biota was not directly connected to global geological events, but affected by the regional event, such as the indosinian movement.
Key words:  strontium isotope  Luoping biota  Anisian period  marine carbonate rocks  Yunnan