| 云南兰坪—思茅盆地江城勐野井钾盐矿床SHK4孔含盐系粘土矿物特征及其成钾环境指示意义 |
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| 关键词:salt-bearing strata analysis of clay minerals hypersaline environment late Cretaceous Lanping-Simao Basin |
| 基金项目:国家“973”计划项目第四课题“兰坪—思茅新生代残留盆地成钾条件、机理和后期演化”(编号: 2011CB403004) |
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| Clay Mineral Characteristics of Salt Sequence in Drill Hole SHK4 of the Mengyejing Potassium Deposit of Jiangcheng, Lanping-Simao Basin, Yunnan Province, and Their Sylvite-forming Significance |
| This paper made a detailed study of clay minerals in salt-bearing strata from drill hole SHK4 located in the Jiangcheng potassium salt basin in the south of Yunnan Province. The authors attempted to reveal the distribution of clay mineral assemblage and its influencing factors, and the significance of these factors for salt (potash) formation. According to the lithology and deposition process, the sequence can be subdivided into three clay mineral units that reflect the transition from dilute phase to salt-forming period and dilute phase. Unit I is characterized mainly by illite (70.6%) and kaolinite (26.7%) with minor amounts of chlorite (2.7%), indicating strong chemical weathering under the condition of hot and rainy climate. The sediments of Units II in the hypersaline environment with mainly illite (53.6%) and chlorite (46.4%) represent a hot arid climate. The main source area also decreased sharply in this period, and this situation to some extent changed the type of clay minerals. Minor amounts of kaolinite (10.7%) and large amounts of illite (44.5%) as well as chlorite (41.8%) appear in Units III, suggesting the intensification of chemical weathering. In addition, good correspondence between the clay mineral assemblage and the brine evolution of SHK4 indicates that the hypersaline environment (rich in K, Mg) had certain restriction on the formation and transformation of clay minerals. Besides, based on the geological structure background of the salt forming period and the characteristics of illite crystallinity (an average of 0.35°Δ2θ) and chemical index (>0.5), the authors hold that the burial diagenesis also had some effect on clay formation. |
| MIAO Wei-liang,MA Hai-zhou,ZHANG Xi-ying,ZHANG Yu-shu,LI Yong-shou.2013.Clay Mineral Characteristics of Salt Sequence in Drill Hole SHK4 of the Mengyejing Potassium Deposit of Jiangcheng, Lanping-Simao Basin, Yunnan Province, and Their Sylvite-forming Significance[J].Acta Geoscientica Sinica,34(5):537-546. |
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