赣东南含黄玉花岗质岩石的成因探讨

本文讨论了出露于赣东南石城、寻乌等地燕山期含黄玉岩浆岩的主要岩石组合及其成矿关系.根据黄玉的结晶习性,提出有部分黄玉是在岩浆晚期至岩浆期后气相阶段结晶的.根据本区含黄玉岩石为强过铝质(ANKC=1.108～28.806),高 F/Cl 比(53～1000)和 Rb/Sr 比(41～176),高的 l_(Sr)(T)(0.7129～0.7308)和低的ε_(Nd)(T)(-5.93～-7.11)值,认为在成因上应属 S-型分异的,而非 A-型.

GENESTS OF TOPAZ-BEARING GRANITIC ROCKS IN SOUTHEASTERN JIANGXI PROVINCE

The principal lithologic assemblage and mineralization of topaz-bearing Yanshanian magmatic rocks in Shicheng and Xunwu counties of southeastern Jiangxi prov- ince were investigated.The crystal habits of topaz contained in these rocks suggest some to- paz may have crystallized during either a late magmatic stage or a post magmatic vapor-phase stage.These topaz components exhibit strong peralumina contents (ANKC=1.108-28.806),high ratios of high F/Cl(53-1000),Rb/Sr ratios of 41-176, high 1_(Sr)(T)(0.7129-0.7308)and enriched isotopic ratios of δ~(18)Oqz of 11.42-14.24‰,while lower ε_(Nd)(T)of-5.93 to -7.11. These analyzed characteristics imply genetic attributes of a highly fractionated S-type magma instead of an A-type magma.