| 云南勐野井钾盐矿床特征,微量元素地球化学及成因探讨 |
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| 引用本文：许效松,吴嘉陵.1983.云南勐野井钾盐矿床特征,微量元素地球化学及成因探讨[J].地球学报,5(1):17-36. |
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| 中文摘要:勐野井钾盐矿床位于云南兰坪、恩茅拗陷带的南部。该带地处藏滇印支地槽褶皱系中段,点苍山、哀牢山断裂带以西,澜沧江断裂带以东。区内发育有巨厚的中新生代红色碎屑岩和含盐建造,本区的主要含盐层为晚白垩世至老第三纪勐野井组。 勐野井组有上下两套含盐层,中部为棕红色钙泥质粉砂岩,下含盐层在区域上是含膏层;上含盐层为石盐岩夹钾盐透镜体。下覆地层是上白垩统扒沙河紫红色石英砂岩,上覆为老第三系等黑组棕红色粉砂岩。矿区为一向斜构造呈北西—南东向分布,盐矿体呈穹窿状,石盐层平均厚196米,钾盐厚29米,NaCl平均含量71.67％ KCl 8.70％,为混有碎屑物的氯化物型钾盐矿床。 本文研究了富钾盐层剖面结构、碎屑物沉积特征、溴、铷、锶、硼等微量元素赋存规律及其在寻找钾盐矿床工作中的标志意义,并探讨了盐矿床的成因。全文蒙袁见齐教授审阅,并提出修改意见,在此表示感谢。 |
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| POTASH DEPOSITS IN MENGYEJING, YUNNAN——A STUDY OF CERTAIN CHARACTERISTICS, GEOCHEMISTRY OF TRACE ELEMENTS AND GENESIS OF THE DEPOSITS |
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| Abstract:The Mengyejing potash deposits, found in the "red" Mengyejing Formation of Upper Cretaceous to Paleogene ages, are located in the southof the Lanping-Simao depression zone between the Ailaoshan and Lancangjiang faults. The salt sequence consists of mixed (sedimentary rocks characterizedby repeated occurrence of chemical evaporites and clastic sediments. Thetypical section may be subdivided into nine rhythmical layers which fallinto three compositional units, i.e., the upper and lower halite beds andmiddle potash member. Trace elements of the deposits have been studied rather systematically. The average content of Br in halite is 127 ppm, in grey sylvite, 2060ppm, and in carnallite, 1399 ppm, with the exception of low Br contentin carnallite, that of the other two falls within the respective theoretical value. The average amounts of Rb in sylvite and carnallite are respectively 50 ppm and 60 ppm. Although Rb in the sylvite is more than thatof the theoretical value from sea water, however, that in the carnallitefalls within the theoretical value. This shows that the parent brine wasof marine and deep-level water source. The red sylvite associated with carnallite has abnormally low Br(1229 ppm) and abnormally high Rb (67 ppm) as compared with primarygrey sylvite. These facts can be explained satisfactorily if it is a secondary leaching product from carnallite. Br in the halite profile increases upward slightly. But there is evident rising of the Br curve at the points where the lower or the upperhalite bed passes into the middle potash member with saw-like variationin between, indicating that the brine giving rise to the potash precipitation has reached the "dry-lake" stage. Strontium and boron have substituted respectively for Ca++ and SO_4in anhydrite, thus denoting the diluting of the brine, while celestite, boracite and the presence of boron in absorption form are related closelyto the potash layers and may indicate its concentration in related salts. |
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