青海纳日贡玛斑岩钼(铜)矿含矿斑岩矿物学特征及成岩成矿意义  

Mineralogical Features of Porphyries in the Narigongma Mo(-Cu) Deposit,Southern Qinghai and their Implications for Petrogenesis and Mineralization

作　　者：郝金华[1,2] 陈建平[1,2] 田永革 李玉龙 尹京武[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学国土资源与高新技术研究中心,北京100083 [3]青海地质调查研究院,西宁810012

出　　处：《地质与勘探》2010年第3期367-376,共10页Geology and Exploration

基　　金：国家科技支撑计划子课题项目(2006BAB01A08);中国地质大调查项目(1212010630804)资助

摘　　要：本文侧重于矿物学特征分析对纳日贡玛赋矿斑岩进行了研究,结果表明:斑岩中黑云母斑晶种属为含铁金云母和富镁黑云母,角闪石种属为镁角闪石、透闪石与阳起石。纳日贡玛含矿斑岩属于I型花岗岩类,由幔源岩浆同熔壳源物质而形成;斑岩结晶压力值为1.18×108～1.39×108Pa;闪长玢岩和黑云母花岗斑岩的结晶温度为550℃～650℃,而浅色花岗斑岩则下降为500℃～550℃。斑岩中黑云母的Mg/Fe、Ti、Al、K、Na、Ca及F、Cl等元素含量及比值可以显示纳日贡玛具有良好的含矿性。纳日贡玛结晶压力、温度都较玉龙矿带低,反映纳日贡玛结晶岩浆房更靠近地表。纳日贡玛岩浆源区向壳源区靠近,而玉龙矿带则更靠近幔源区,表明成岩源区中壳幔物质混合比例的不同。This paper focuses on the study of the ore-bearing porphyry of the Narigongma deposit through mineralogical and geochemical analyses. The result reveals that the biotite phenocrysts in the deposit are ferri-phologopite or magnesium-rich biotite and the amphiboles are magnesium amphiboles,tremolites or actinolites. The porphyry should be classified as I-type granite,which was originated from the mantle,meanwhile assimilated crustal material is also present. The crystallization pressure of the porphyry is 1.18~1.39×108Pa. The crystallization temperature of the biotite porphyry is estimated to be 550℃~650℃,whereas that of the leucogranitic porphyry is about 500℃~550℃. The geochemical characteristics regarding ratio Mg/Fe and contents of Ti,Al,K,Na,Ca,F and Cl suggest favorable ore-forming potential in the Narigongma deposit. The crystallization temperature and pressure are both lower than that in the Yulong ore-forming belt,which indicates that the former was probably developed shallower than the latter. Besides,the inferred difference in the forming depth also suggests that more crustal material had contributed in the formation of the shallower Narigongma deposit.

关 键 词：矿物学特征 黑云母 成岩成矿 纳日贡玛 青海南部 

分 类 号：P618.65[天文地球—矿床学] P581[天文地球—地质学]