Sr, S, and O Isotope Compositions of Evaporites in the Lanping-Simao Basin, China

被引：17

作者：

Shen, Lijian ^{[1
]}

Wang, Licheng ^{[2
]}

Liu, Chenglin ^{[1
]}

Zhao, Yanjun ^{[1
]}

机构：

[1] Chinese Acad Geol Sci, Inst Minerals Resources, MNR Key Lab Metallogeny & Mineral Assessment, Beijing 100037, Peoples R China

[2] Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Continental Collis & Plateau Uplift, CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China

来源：

MINERALS | 2021年 / 11卷 / 02期

基金：

中国国家自然科学基金;

关键词：

evaporites; the Lanping– Simao Basin; continental setting; sulfates; Sr; S; O isotopes;

D O I：

10.3390/min11020096

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

Evaporites are widely distributed within continental "red beds" in the Lanping-Simao Basin, west Yunnan, China. Sr (Strontium), S (Sulfur), and O (Oxygen) isotope compositions have been measured on 54 sulfate or/and sulfate-bearing samples collected from Lanping, Nuodeng, Jinggu, Mengyejing, Baozang throughout the Lanping-Simao Basin. The Sr-87/Sr-86 ratios of all samples (0.708081 to 0.710049) are higher than those of contemporaneous seawater, indicating a significant continental contribution to the drainage basin. Sulfates in the Lanping Basin have higher Sr-87/Sr-86 ratios (0.709406 to 0.710049) than those (0.708081 to 0.709548) in the Simao Basin. Nevertheless, the delta S-34 values of gypsums (13.4 parts per thousand to 17.6 parts per thousand) in Lanping and Baozang fall within the range of Cretaceous seawater. Gypsums from a single section in Baozang have trends of decreasing delta S-34 values and increasing Sr-87/Sr-86 ratios from base to top, indicating continental input played an increasingly significant role with the evaporation of brines. High delta S-34 values (20.5 parts per thousand to 20.7 parts per thousand) of celestites in Lanping are probably caused by bacterial sulfate reduction (BSR) process in which S-34 were enriched in residual sulfates and/or recycling of Triassic evaporites. The reduced delta S-34 values of gypsums (9.5 parts per thousand to 10.4 parts per thousand) in Nuodeng could have been caused by oxidation of sulfides weathered from Jinding Pb-Zn deposit. The complex O isotope compositions indicate that sulfates in the Lanping-Simao Basin had undergone sulfate reduction, re-oxidation, reservoir effects, etc. In conclusion, the formation of continental evaporites was likely derived from seawater due to marine transgression during the Cretaceous period. Meanwhile, non-marine inflows have contributed to the basin significantly.

引用

页码：1 / 20

页数：21