| 川东盆地长寿地区三叠系杂卤石的发现及其成因研究 |
| Received:July 18, 2014 Revised:August 15, 2014 点此下载全文 |
| 引用本文：WANG ShuLi,ZHENG MianPing.2014.Discovery of Triassic polyhalite in Changshou area of East Sichuan Basin and its genetic study[J].Mineral Deposits,33(5):1045~1056 |
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| 基金项目:本文得到国家自然科学重点基金项目(编号: U0833601)、中国地质调查局项目(编号: 1212010011810)和青年科学基金项目(编号: 41403019)的联合资助 |
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| 中文摘要:笔者先后2次对川东盆地盐矿实地考察,并系统采集了样品。水溶化学分析结果表明,长寿地区T1j4-2地层中岩盐w(K+)较高,最高可达3.25%,明显高于其他盐矿点(合川盐矿、云阳盐矿及万州高峰盐矿)。岩盐Br-含量也较高;Br×103/Cl值相对较高,一般为0.26~0.36,最大可达0.41,已达到晚期石盐沉积,甚至是钾镁盐早期沉积阶段。而后又对K+含量较高的样品(不含KCl)进行配矿分析,同时结合岩矿鉴定及XRD分析验证,首次发现和确定长平3井的主要含钾矿物为杂卤石,样品中不含钾石盐(KCl)。通过对样品薄片镜下观察,杂卤石为自形-半自形的板状和柱状及叶片状形态,结合杂卤石与石盐的接触关系及Br×103/Cl值分析,认为长平3井杂卤石为原生沉积成因,而非如前人所认为的四川盆地其他地区的杂卤石成因——后期含钾镁较高的热卤水交代硬石膏而形成。这一认识对该区寻找可溶性钾盐具有一定的启示作用。 |
| 中文关键词:地球化学 三叠系 杂卤石 成因研究 沉积阶段 长寿地区 川东盆地 |
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| Discovery of Triassic polyhalite in Changshou area of East Sichuan Basin and its genetic study |
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| Abstract:This study was based on two times of field work and systematic sampling of rock salt and gypsum in the East Sichuan Basin. Water soluble chemical analyses of these samples show that the concentrations of K+ of T1j4-2 in the Changshou area are higher than those of other areas (Hechuan area, Yunyang area and Gaofeng area), with the maximum value reaching 3.25%. The values of bromine are higher, Br×103/Cl ratios of the halite are also high, with most of them ranging between 0.26 and 0.36 and the maximum even reaching 0.41, indicating that the halite concentration in this drill hole reached the late stage of halite deposition or even reached the early stage of the potassium-bearing salt. Based on the ore-blending analysis of the sample with relatively high K+, it is thought that the main potassium-bearing mineral is polyhalite. XRD analysis and rock-mineral determination show that there is no sylvite (KCl) in the samples. Based on the microscopic observation of the euhedral-subhedral platy, columnar and leaf-like shapes of polyhalite and the contact relation between polyhalite and halite as well as the Br×103/Cl ratios, the authors hold that the polyhalite genetically belongs to primary deposition rather than being formed by the replacement of anhydrite by late-stage high-potassium and high-magnesium hot brines as considered by some previous researchers for the genesis of polyhalite in some other areas of the Sichuan Basin. The authors' understanding is of some inspiration significance in the search for soluble potash salt deposits in this area. |
| keywords:geochemistry Triassic polyhalite genetic study depositional phase Changshou area East Sichuan Basin |
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