青海兴海赛什塘铜矿区条带状构造成因研究

Genesis of Ribbon Structure in Saishitang Copper Oredistrict, Xinghai County,Qinghai Province

在新的宏微观资料的分析研究基础上,依内部组构与发育特征的不同,将青海省兴海县赛什塘铜矿床的条带状构造分为两类。研究表明它们形成于同构造的区域变质变形与接触(交代)变质间的复合叠加作用,属先成或同生面状构造影响控制下的等化学变质与选择性(交代)蚀变生成的一种变余或新生优选定向组构(//S1或S0)。从构造早期的脆韧性变形到晚期脆性变形过程中,成生发育两个世代的同构造新生矿物组合,分别组成反映其形成阶段和发育特点的两类条带状构造。这为矿床的成因演化研究提供了新的依据。

Based on the new macro--microscopic data, two ribbon types have been differentiated according to the internal fabric and developmental characteristics of the ribbon structure in the Saishitang copper deposit, Xinghai County, Qinghai Province. Detailed studies revealed that ribbon structure is a palimpsest or neomorphic directional texture （//SI or SO ） as a result of isochemical metamorphism and selection replacement of protolith, typically controlled by early-formed and syntectonic planer structures, and reflects the superposition of the syntectonic contact metasomatism and regional metamorphism and deformation. Two styles of ribbon structures, respectively defined by two generations of syntectonic mineral assemblage representing the structural development and formation stage, are developed during the transition from early-stage brittle ductile deformation to late-stage brittle fracture for deformation manner of the host rocks. It is significant to carry out study of ribbon structures in Saishitang and to gain further knowledge about genesis and evolution of deposit.