摘要:
位于陕北奥陶纪盐盆东二盐凹东部的钾盐科学勘查井——绥钾1井,揭示了奥陶系马家沟组马五6亚段厚度为118.17 m,其中岩盐厚度累计100.38 m。本次工作将该井马五6亚段划分为4个成盐韵律,并利用示钾微化反应和岩盐样品溴、氯、钾元素分析为主要分析手段对绥钾1井岩盐段的含钾性进行评价,结果表明:该井马五6亚段发育累计厚度达64.7 m的厚层钾石盐高矿化段,发育4套成盐韵律,含钾石盐分布在相对完整的韵律II和韵律III中大部分的褐红色和褐色石盐中,以韵律II含钾性最好,石盐顶部的泥质夹层起到了保护作用;本井整体 K+含量在0.08%~1.24%之间,一般在0.1%以上,平均为0.23%,局部井段钾含量接近边界工业品位; Br-含量在90×10-6~400×10-6之间,平均为242×10-6; Br-×103/Cl-(溴氯系数)在0.17~0.98之间,平均为0.45。溴值和溴氯系数绝大部分达到钾石盐-光卤石沉积阶段。利用绥钾1井和盐盆内其他地区9口盐探井的平均钾含量数据编制了陕北奥陶纪盐盆马五6亚段 K+含量(%)变化趋势图,该图指示东南部的东二盐凹是研究区较有利的含钾盐凹。绥钾1井马五6亚段厚层钾石盐高矿化段的发现,不仅揭示了该盐盆巨大的找钾前景,也为今后钾盐勘查工作部署指明了方向。
Abstract:
Located on the east side of the Suide salt depression in Northern Shaanxi salt basin, the scientific potash prospecting well of SJ1 encountered 118.17 m of theM56 member of the Ordovician Majiagou Formation. The cumulative thickness of the salt series in the member is 100.38 m. In this study, theM56 member of well SJ1 was divided into 4 salt rhythms, and the potassium content in the salinastone section was evaluated by in-situ micro-chemical reaction testing and quantitative analysis in the laboratory. The data obtained indicate that the cumulative thickness of mineralized potash in theM56 member is 64.7 m, comprising 3 salt rhythms. Potash salt monolayer is brownish red or brown in color in the relatively complete rhythm II and rhythm III, and potash salt in rhythm II has the highest content of potassium, with the argillaceous interlayer at the top playing the protective role. The potassium content for part of the section is close to industrial grade, with potassium ion content ranging from 0.08% to 1.24%, mostly in excess of 0.1% and averagely 0.23%. The Br- content is from 90×10-6 to 400×10-6, averaging 242×10-6; the Br-×103/Cl- ratio ranges from 0.17 to 0.98, averaging 0.45. The content of Br- and the Br-×103/Cl- ratio indicate that most of the samples have reached the precipitation stage for potash and carnallite. Using the average K+ (%) content values for well SJ1 and the other eight boreholes in the salt depression, the authors drew a trend map for the change in the K+ (%) content, which shows that the better potash depression is the second east salt depression. The discovery of the thick highly mineralized sylvite layer in the well not only supports the potential for potash prospecting in the area but also provides clear indications for the exploration of potash salt.
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