陕北奥陶系钾盐层位的发现与研究

Discovery and Study on Ordovician Potash Salt Horizons in Northern Shaanxi

陕北奥陶系是一个大型海相蒸发岩盆地,笔者在盆地东侧下奥陶统马家沟组,发现了钾石盐、光卤石等钾盐矿物,这是世界上首次在奥陶系发现钾盐。笔者较详细地研究了地质条件、含盐岩系剖面特征、物质成分和地球化学等,探讨了蒸发岩沉积的古地理环境和成盐模式。据蒸发岩组成特征、结构构造、赋存状态、组合关系、地球化学诸方面的综合研究,认为陕北盆地钾盐沉积形成于残留卤水湖和干盐湖阶段。

The Ordovician in northern Shaanxi constitutes a large marine evaporite basin. In the Early Ordovician Majiagou Formation, on the east side of the basin, the authors have discovered such potash salts as sylvite, carnallite and rinneite, which is the first discovery of potash salts in the Ordovician in the world. Geochemical study indicates that the potassium content in samples may reach a maxium of 2. 50% and that the bromine content is generally 400 × 10-6. The assemblage of saline minerals is the same as that in other marine potash deposits in the world.