摘要
地质地球化学对比研究表明,玉龙含矿与非舍矿斑岩是由岩石圈地慢中交代成因的金云母-石榴石单斜辉石岩脉发生不同程度部分熔融而形成的。分矿斑岩是最早阶段熔融体,主要是由交代成因脉中副矿物(如磷灰石和碳酸盐矿物等)和舍水矿物金云母发生部分熔融而形成的,因而富含 F、Cl 和水等挥岌份,加上该阶段岩浆具有高氧化性特征,从而富含 Cu 等成矿元素;非含矿斑岩是交代成固咏相对较高熔融程度的产物,单斜辉石和石榴石介入了熔融作用,岩浆熔体相对贫乏F、Cl 和水等挥发份,加上该阶段岩浆具有较低的 f_(0_2),从而不利于成矿。斑岩体全岩的 F 和 Cl 含量(舍矿斑岩 F>1200 ppm,Cl>150 ppm;非含矿斑岩 F<1200 ppm,Cl<150 ppm)、K_2O/Na_2O(含矿斑岩>1.2,非含矿斑岩<1.2)和 Sm/Yb(含矿斑岩>6.5,非含矿斑岩<6.5)比值以及黑云母中的 Fe^(3+)/Fe^(2+)比值(含矿斑岩>0.7,非舍矿斑岩<0.7)是区分含矿与非含矿斑岩的重要地球化学参数。含矿斑岩与非分矿斑岩具有非常相似的 Sr-Nd-Pb 同位素组成,,表明含矿与非含矿班岩具有相同的源区。
Geological and geochemical comparison studies indicate that the ore-bearing and barren porphyries in the Yulong porphyry Cu deposit were derived by different degree partial melting of the vein of phlogopite-garnet clinopyroxenite in an lherzolitic lithosphere. The ore-bearing porphyry represents the earliest melt derived by partial melting of accessory phases such as apatite and carbonate and hydrous mineral of phlogopite, and thus contains high contents of volatiles such as F, Cl and water, which is preferred for Cu to be extracted and enriched. The barren porphyry is the product at relatively high degree partial melting involving clinopyroxene and garnet, and thus depleted in volatiles, which makes it to be evolved as barren one. F and Cl contents （F 〉 1200 ppm, Cl 〉 150 ppm for orebearing porphyry and F 〈 1200 ppm, Cl 〈 150 ppm for barren porphyry） and K2O/ Na2O （ 〉 1.2 for ore-bearing porphyry and 〈 1.2 for barren porphyry ） , Sm/Yb （ 〉 6. 5 for ore-bearing porphyry and 〈 6. 5 for barren porphyry ） ratios of porphyries and Fe^3＋/Fe^2＋ ratios （ 〉0. 7 for ore-bearing porphyry and 〈0. 7 for barren porphyry） of biotite are the important geochemical parameter to discriminate ore-bearing and barren porphyries. The ore-bearing porphyries share similar Sr-Nd-Pb isotopic compositions as the barren porphyries, suggesting they have similar source regions.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第10期2561-2566,共6页
Acta Petrologica Sinica
基金
国家重点基础研究发展规划项目(项目编号:2002CB412600)
国家基金委优秀创新群体项目(项目编号:40221301)资助
关键词
含矿斑岩
非含矿斑岩
地球化学对比研究
玉龙斑岩铜矿床
Ore-bearing porphyry, Barren porphyry, Geochemical comparison study, Yulong porphyry Cu deposit
