酒西盆地下沟组湖相白烟型喷流岩岩石学特征

Lithological characteristics of sublacustrine white smoke type exhalative rock of the Xiagou Formation in Jiuxi Basin

酒西盆地下白垩统下沟组首次发现的湖相白烟型喷流岩,以其复杂的矿物组分和丰富的沉积构造业已引起众多地质工作者的重视。本文通过深入系统的岩石学研究,按物质组分的组合特征,从此类喷流岩中划分出6种热水矿物组合,分别为钠长石-铁白云石或铁白云石-钠长石组合、石英-钠长石-铁白云石组合、石英-重晶石-钠长石-铁白云石组合、石英-方沸石-钠长石-铁白云石组合、地开石-铁白云石组合和单一铁白云石组合,根据热水矿物组合和结构构造特征,可将下沟组喷流岩划分成4种成因类型,分别为脉状充填型、水爆角砾型、盆地沉积型和区域扩散型,不同成因类型的喷流岩具有不同的热水矿物组合特征和热水沉积地质意义,在此基础上,建立了下沟组湖相白烟型喷流岩热水沉积模式,

A number of geological workers take it seriously that sublacustrine white smoke type exhalative rock is firstly discovered and contains complicated mineral component and rich special sedimentary structure in Xiagou Formation, Lower Cretaceous in Jiuxi basin. The authors research thoroughly the lithological characteristics of the exhalative rock which is divided into six types of hydrothermal mineral assemblages mainly including albite-ferrodolomite, quartz-albite-ferrodolomite, quartz-barite-albite-ferrodolomite, quartz-analeite-albite-ferrodolomite, dickite-ferrodolomite and ferrodolomite according to assemblage characteristics of the material components and which is divided into four types of the sedimentary types, i e, filling lode rock type, water bursting breccia type, basin depositing type and region diffusing type in term of hydrothermal mineral assemblages and the texture and structure features. The different genetic type of the exhalative rock has the different hydrothermal mineral assemblage characteristic and the geological significance of hot water deposition. Based on all above, the authors establish sedimentary model of sublacustrine white smoke type exhalative rock in Xiagou Formation, Lower Cretaceous in Jiuxi Basin .