【摘要】 本文分析了四川—重庆华蓥山地区天青石矿床的野外宏观特征和微观特征,对三种主要类型的天青石矿石:层状天青石矿石、巨晶天青石矿石和条带状天青石矿石中的暗色条带天青石和白色条带天青石进行了野外产状、结构构造特征、稀土元素含量特征、天青石包裹体成分和包裹体盐度的比较分析,结果表明,层状矿石和条带状矿石中的暗色条带天青石是沉积形成的,巨晶矿石和条带状矿石中的白色条带天青石属热卤水成因。更多还原

【Abstract】 Celestite deposits in the Huaying Mountains area, in Sichuan Province and new formed Chongqing Municipality, ever called eastern Sichuan celestite deposits, are made up of three natural ore types;banded celestite ore,megacryst celestite ore and bedded celestite ore. According to the ore occurrence,celestite inclusion composition and salinity,and rare earth element characteristics, these ores can be divided into two genetic types. Megacryst ore is pure in quality. Bedded ore is made up of granular celestite and dolomiic mud filling the interstices of celestite crystals. Banded ore is made up of dark celestite bands and white celestite bands,both occuring as interbeds. The dark celestite band is composed of granular celestite with dolomitic mud filling the interstices of granular celestite. The white celestite band is composed of coarse-grained celestite, which is pure in quality. The boundaies between dark celestite bands and white celestite bands is clear-cut. The dark celestite bands are in some cases cut by white celestite bands. In terms of composition of celestite inclusions, bedded ores and dark banded celestite in the banded ores are approximately the same; while megacryst celestite ores are close to white banded celestite in the banded ore. The salinities of celestite inclusions of the former two are 2. 0-2. 7 wt%NaCl equiv. ; while those of the latter two are 6. 2-11. 2 wt% NaCl equiv. The δEu values of the former two are 0. 71 -0. 91 , showing negative anomaly; while the δEu values of the latter two are 1. 25-1. 94. showing positive anomaly. These characteristics indicate that the former two and the latter two do not belong to the same genetic type.Macroscopic and microscopic evidence indicate that the bedded celestite ore and the dark banded celestite are of sedimentary origin,while the megacryst celestite ore and the white banded celestite are of hot-brine origin.The main evidence of sedimentary celestite ore is as follows:① The ore is composed of granular celestite, and has an anhedral granular texture and the interstitial material is dolomite. ② There is parallel bedding in bedded celestite ore. ③ Bedding bypasses celestite grains. ④ There are celestite gravels with a patina in the dark celestite bands. ⑤ There is quartzine among the ce-lestite grains in the bedded celestite ore, which represents an evaporative enviroment. ⑥ The sulphur and strontium isotopic compositions show that sulphur and strontium in the celestite ore came from sea water. ⑦ There are clear stratabound characteristics and the ore beds are controlled by strata strictly. ⑧ It is found that bedded celestite ore drops down from the roof, which is encircled by megacryst celestite.The main evidence of celestite of hot-brine origin is as follows:① Megacryst celestite ore and white banded celestite are made up of giant- coarse-grained celestite,which is pure in quality, and there is no interstitial materal. ② The homogenization temperature of the inclusions is higher. ③ The δEu values of celestite are positive, which are similar to these of the Pacific hot spring waters and the Red Sea hot-brine waters. ④ Megacryst celestite ore occurs in the upper part of the structure and is limited by structural space and not persistent laterally. ⑤ Megacryst celestite ores contain some celestite ores dropping down from the roof, which indicates that megacryst celestite was formed simultaneously with or after folding.更多还原