东秦岭东段南阳独山玉矿成因和致色机理  

Genesis and Chromogenic Mechanism of Dushan Jade Ore of Nanyang in Eastern Section of East Qinling Mountions

作　　者：信涵 陈国超[1] 王皓宇 付星芮 李玟超 姬果果 王照雄 张璟 张锋 张荣臻 马娟娟 XIN Han;CHEN Guochao;WANG Haoyu;FU Xingrui;LI Wenchao;JI Guoguo;WANG Zhaoxiong;ZHANG Jing;ZHANG Feng;ZHANG Rongzhen;MA Juanjuan(School of Civil Engineering,Nanyang Institute of Technology;Henan Academy of Geology;Nanyang City Museum)

机构地区：[1]南阳理工学院土木工程学院,河南省南阳市473000 [2]河南省地质研究院,河南省南阳市473000 [3]南阳市博物院,河南省南阳市473000

出　　处：《现代矿业》2024年第11期40-45,共6页Modern Mining

基　　金：资源与生态环境地质湖北省重点实验室开放基金项目(编号:HBREGKFJJ-202304);河南省战略性金属矿产成矿规律与找矿预测研究项目(编号:2023-903-XM006)。

摘　　要：独山玉呈脉状产于南阳市独山辉长岩岩体内,选取干白玉、绿白玉、紫独玉、黑独玉和多色杂玉作为代表性样品,对其进行了矿物组成和显微构造研究,并结合早期成果,探讨了独山玉的成因、致色机理和地球动力学机制。研究表明,商丹洋的俯冲作用使弧后拉张,形成了二郎坪弧后洋盆;由于俯冲流体的交代,使地幔楔部分熔融,形成了独山辉长岩的原始镁铁质岩浆。岩浆经过堆晶作用,形成了层状辉长岩原岩,通过早期的动力变质作用以及晚期的热液变质作用,使原岩中的矿物蚀变、重结晶,进而形成独山玉,其颜色与矿物组成及微量元素分布相关。斜长石含量越高,平均颗粒度越小,斑晶含量越少,结合越紧密,独山玉越透明;黝帘石含量高,独山玉呈白色;暗色矿物角闪石、透辉石和透闪石含量高,独山玉呈黑色;微量元素Cr^(3+)、Fe^(3+)、Fe^(2+)、Ti^(4+)及Mn^(3+)可分别使独山玉呈绿色、紫色、黄色和红色。Dushan jade is produced in a vein shape in the Dushan gabbro of Nanyang City.Taking dry white jade,green white jade,purple jade,black jade and polychromatic mixed jade as representative samples,the mineral composition and microstructure of the samples are studied,and the genesis,chromogenic mechanism and geodynamic mechanism of Dushan jade are discussed.The results show that the subduction of Shangdan Ocean stretched the back arc and formed the Erlangping back arc ocean basin.Due to subduction fluid replacement,the mantle wedge partially melted and formed the original mafic magma of Dushan gabbro.The stratified gabbro protolith was formed by the accumulation of magma crystals.Through the early dynamic metamorphism and the late hydrothermal metamorphism,the minerals in the protolith were altered and recrystallized to form Dushan jade.Its color is related to the mineral composition and the distribution of trace elements.Higher plagioclase content,smaller average particle size,lower phenocryst content,closer combination,and greater transparency result in lighter Dushan jade.Higher zoisite content leads to white Dushan jade,while elevated levels of dark minerals like amphibole,diopside,and tremolite produce black Dushan jade.Trace elements such as Cr^(3+),Fe^(3+),Fe^(2+),Ti^(4+)and Mn^(3+)impart green,purple,yellow and red hues to Dushan jade,respectively.

关 键 词：独山玉 独山辉长岩 矿床成因 致色机理 

分 类 号：P619.28[天文地球—矿床学]