重庆玉峡天青石矿床矿石结构构造特征及成因意义

Characteristics of ore texture and structure of Yuxia celestite deposit in Chongqing and its genetic significance

在综合分析矿床的基本地质特征基础上,重点开展显微镜下矿石结构构造的分析研究,结合矿段的岩相古地理分析,探讨重庆铜梁县玉峡天青石矿床的成因机制。玉峡天青石矿床的矿石矿物主要是天青石和菱锶矿,以及少量硬石膏、石膏;脉石矿物主要是白云石和少量方解石。矿石构造主要有条纹-条带状构造、脉状构造、角砾状构造、次生淋滤构造(钟乳状、皮壳状、蜂窝状构造);矿石结构为自形-半自形晶粒结构、他形晶粒结构、交代结构及交代残余结构,表生期菱锶矿常见放射状、纤维状集合体。条纹条带状构造是主要矿石构造,与沉积作用有关;脉状构造、次生淋滤状构造、交代残余结构等也为矿床成因分析提供了重要依据。玉峡天青石矿床为蒸发沉积(盐类)矿床。

Based on the comprehensive analysis of the basic geological characteristics,the genetic mechanism of the Yuxia celestite deposit in Tongliang of Chongqing is discussed by study of ore texture and structure under the microscope and analysis of lithofacies paleogeography.It shows that ore minerals of the deposit are celestite(SrSO 4)and strontianite(SrCO 3),with minor anhydrite and gypsum.Gangue minerals are composed of dolomite with small amount of calcite.Ore structures include stripe structure,banded structure,vein structure,breccias structure,secondary leaching structures(stalactitic structure,crustose structure and honeycomb structures).Commonly occurred ore textures are euhedral-subhedral crystalline texture,poikilocrystallic texture,metasomatic texture and metasomatic relict texture.Radial and fibrous aggregates occur frequently in the epigenetic stage.Stripe structure is the major structure of the ore,which is related to sedimentation.Vein-like structures,secondary leaching-like structures,and metasomatic residual structure also provide important basis for the genetic analysis of the deposit.It is believed that the Yuxia celestite deposit is an evaporative deposit(salt)deposit.