贵州晴隆沙子锐钛矿矿床与黔西南红土型金矿床的成矿差异性

Metallogenic Difference between Qinglong Shazi Anatase Deposits and Lateritic Gold Deposits in Southwestern Guizhou Province

黔西南有些地段的大厂层——金矿源岩残存裸露于地表的古喀斯特洼地中,第四纪强风化作用导致矿源岩中金元素富集,形成黔西南红土型金矿床。贵州晴隆沙子一带中二叠统茅口组灰岩顶部形成古喀斯特高地与喀斯特洼地,在低温、低压、弱碱性水体中锐钛矿晶出被玄武质黏土及褐铁矿等吸附,形成锐钛矿矿床。大厂层——金矿源岩覆盖于锐钛矿体之上,使已形成的锐钛矿得以保存。同时,玄武质黏土、玄武岩残块等,阻碍上覆大厂层——金矿源岩以下的喀斯特进一步发育,使其大厂层——金矿源岩风化不彻底,导致金不富集,仅表现为弱矿化,不能形成红土型金矿床,这就是导致两者成矿差异性的原因。

The ＂gold source rocks of Dachang layer＂ in some area of southwestern Guizhou Province were aintained in the ancient Karst depressions on the earth surface.The strong weathering in Quaternary caused the gold of source rocks to be enriched,forming the lateritic gold deposit in southwestern Guizhou Province.The ancient Karst highland and depressions were formed at the top of Maokou Formation limestone（P2）in Qinglong Shazi area.The anatase was crystallized from alkalescent water in the conditions of low temperature and low pressure,leading to the formation of the anatase deposit by basaltic clay and limonite adsorption.The ＂gold source rocks of Dachang layer＂ covered on the formed anatase ore body to make it preserved.The basaltic clay,basalt residual block,etc.,impeded the upper ＂gold source rocks of Dachang layer＂ and below furthered Karst development,which led to the incomplete weathering of the ＂gold source rocks of Dachang layer＂.The gold there could not be lateritic gold deposit.This was the cause of the ore-forming differences between the two ore deposits.