和(县)含(山)硬石膏矿成因类型、沉积环境及赋矿规律

通过和(县)含(山)硬石膏矿勘查资料,分析研究了该区含矿地层周冲村组(东马鞍山组)岩矿成因类型和代表性剖面岩相划分,认为周冲村组是在早中三叠世缓慢海退和干旱蒸发作用下形成的一套由浅滩—局限海夹潮坪—咸化潟湖—潮上萨布哈的蒸发岩建造,其中的硬石膏矿体主要沉积于咸化潟湖环境;认为早中三叠世的海退和海水咸化过程是循序渐进式发展的,其间发生了许多次小规模海侵或风暴潮,使得咸化潟湖海水的补给和蒸发保持了相对平衡,形成了巨厚硬石膏矿体沉积所需的持续稳定的海水盐度和环境条件;认为早中三叠世的海退有自西向东的退出趋势。同时指出,由于环境差异,本区东部的硬石膏矿品质好于西部。

GenetiC typeS,SedimentAry environment And ore-forminG pAttern of roCkS And minerAlS of Anhydrite in hexiAn And hAnShAn

Based on exploration data on anhydrite in Hexian and Hanshan, this paper analyzed genetic types of rocks and minerals in the ore horizon of the Zhoucun Formation (Dongmaanshan Formation), and lithofacies of representative profile, thought that the Zhoucun Formation is a suit of shoal-restricted sea with tidal flat-salinized lagoon-supratidal sabuha evaporate formed in early-mid Triassic under slow regression and arid evaporation conditions, and anhydrite mainly deposited in salty lagoon environment, and that early-mid Triassic regression and seawater salinization are a process of gradual advance during which a number of small advances of sea or storm tides took place, as a result, the feed of salinized lagoon seawater kept a balance with evaporation, forming a constantly stable seawater salinity and environment condition for a very thick anhydrite deposit, and further that early-mid Triassic regression tended to withdraw from west to east, and the quality of anhydrite is better in east than in west due to environmental difference.