Characteristics of chlorine isotope distribution and analysis on sylvinite deposit formation based on ancient salt rock in the western Tarim Basin |
| |
| Authors: | Email author" target="_blank">Hongbing?TanEmail author Haizhou?Ma Yingkai?Xiao Haizhen?Wei Xiying?Zhang Wandong?Ma |
| |
| Institution: | 1. Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China;Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
2. Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China |
| |
| Abstract: | During formation of the Tarim Basin, there repetitively happened seawater invasion for it was ever connected with wide Paleo-mediterranean
Sea. At the same time, for the application of tectonic and paleoenvironmental condition, the basin deposits many sequences
of thick strata of evaporites, especially in its two largest subbasins of Kuqa in the north and Shaqa in the southwest. Therefore,
the western Tarim Basin has been considered to be a favorable location to prospect ancient sylvinite deposit. But it is unfortunate
that the Br×103/Cl ratio, as a common geochemical index to uncover clues of sylvinite deposit, is almost invalid to indicate the stage of
ancient brine condensation for very low content of bromine in salt rock samples (less than 10−6 commonly) in the western Tarim Basin evaporites. Fortunately, we noticed recently that the values of chlorine isotope (δ
37Cl value) for salt rock samples follow some clear laws from place to place, which in the Shaqa subbasin, all δ 37Cl values of salt rock samples behaved negatively and on the contrary, they all surprisingly showed positive values in the
Kuqa subbasin. Based on conclusions of previous research and referring to the ratios of Br×103/Cl for salt rock or brine samples, we proved that the chlorine isotope (δ 37Cl) could be used as an effective index to find ancient sylvinite deposit in those evaporites rock basin with low content
of Br element background, such as the Tarim Basin. Thus according to the new index of chlorine isotope, we conclude that the
concentration of ancient brines formed ancient salt rocks is much more concentrated in the Shaqa subbasin than that in the
Kuqa subbasin. Particularly, the δ 37Cl value of salt rock in Kashi depression of the western Shaqa subbasin is greatly negative (<-1.00‰), which may predicate
that the ancient brine has been concentrated to the terminal stage of salt deposit or even the later stage of sylvinite deposit.
Then it is possible to find sylvinite-bearing deposits around the western region (periphery of Kashi depression) of the Shaqa
subbasin if we carry out more careful exploration in later works. |
| |
| Keywords: | the Tarim Basin chlorine isotope ancient salt rock ancient sylvinite deposit deposit stage |
| 本文献已被 CNKI 万方数据 SpringerLink 等数据库收录！ |
|
