| 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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| 引用本文：苗卫良,马海州,张西营,张玉淑,李永寿.2013.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[J].地球学报,34(5):537-546. |
| DOI：10.3975/cagsb.2013.05.04 |
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| 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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| 中文摘要:SHK4孔揭示了晚白垩世含盐系勐野井组(K2me)地层, 根据岩性特征将该孔划分为三个粘土矿物单元, 依次反映了从淡化期到成盐期再到淡化期的转换过程。单元Ⅰ粘土矿物主要为伊利石(70.6%)和高岭石(26.7%), 以及极少量的绿泥石(2.7%)。处于高盐度环境下的单元Ⅱ沉积物粘土矿物主要为伊利石(53.6%)和绿泥石(46.4%)。而这一时期物源区面积的急剧减小在一定程度上改变了粘土矿物的输入类型。单元Ⅲ的粘土矿物主要为伊利石(44.5%)、绿泥石(41.8%)和高岭石(10.7%)。另外粘土矿物组合与沉积过程中的卤水演化程度有着良好的对应关系, 表明富K、Mg的高盐度环境对粘土矿物的形成转化应具有一定的制约作用。考虑到含盐系地层发育时研究区的地质构造背景, 以及SHK4孔伊利石结晶度(平均0.35°Δ2θ)与化学指数(>0.5)的特征, 认为埋藏成岩作用对SHK4孔粘土矿物的形成也具有一定程度的影响。 |
| 中文关键词:含盐系 粘土矿物分析 高盐度环境 晚白垩世 兰坪—思茅盆地 |
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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 |
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| Abstract: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. |
| keywords:salt-bearing strata analysis of clay minerals hypersaline environment late Cretaceous Lanping-Simao Basin |
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