胶东金矿区矿田体系中基性-中酸性脉岩的碳、氧同位素地球化学研究  

Research on C, O Isotopic Geochemistry of Intermediate-Basic and Intermediate-Acid Dykes In Goldfields of Jiaodong Peninsula

作　　者：孙景贵[1] 胡受奚[1] 沈昆 姚凤良[3] 

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室,南京210093 [2]山东省地质科学研究院,济南250013 [3]吉林大学地球科学学院,长春130061

出　　处：《岩石矿物学杂志》2001年第1期47-56,共10页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目! ( 4913312 0 )资助

摘　　要：胶东金矿区矿田体系产出的脉岩是一套富含碳酸盐矿物相的中基性 -中酸性脉岩 ,岩石类型主要有煌斑岩、安山玢岩类。对部分矿田体系产出脉岩的碳酸盐 (方解石 )碳、氧同位素及全岩氧同位素的研究表明 :该套脉岩的δ18OSMOW ,方解石 、δ13 CPDB ,方解石 和δ18OSMOW ,全岩 值分别为 6 .9‰～ 11.6‰、- 0 .9‰～ - 3.6‰、5.8‰～ 7.4‰。通过对源区的δ13 CPDB、δ18OSMOW 特征和同位素效应与就位环境关系的探讨 ,初步认为 :各矿田内的脉岩为同源岩浆演化的产物 ;初始岩浆来源于洋壳俯冲提供的流体与岩石圈地幔发生交代作用而形成的富集地幔 ,源区的δ18OSMOW ,碳酸盐 、δ13 CPDB ,碳酸盐 、δ18OSMOW ,岩浆 分别为 9.2‰±、- 4 .4‰±和 5.8‰± ;岩浆演化过程中同位素效应的差异是导致各矿田体系脉岩的碳。The intermediate_basic and intermediate_acid dykes existent in the gold fields of Jiaodong peninsula, China, belong to a suite of intermediate_basic and intermediate_acid carbonate minerals_rich rocks consisting of lamprophyres and andesite porphyrites. Detailed studies of carbon and oxygen isotopes of carbonate minerals of the dykes and oxygen isotopes of the dykes in the gold fields (i.e. Linglong, Rushan and Sanjia gold deposits) show that δ 13 C PDB, calcite , δ 18 O SMOW calcite and δ 18 O SMOW,whole-rock values of the intermediate_basic and intermediate_acid dykes in the gold fields are in the range of -3.6‰～-0.9‰, 6.9‰～11.6‰ and 5.8‰～7.4‰ respectively. These data were used to determine the δ 18 O SMOW,whole-rock , δ 18 O SMOW calcite and δ 13 C PDB,calcite values of the magmas in the source region and to study the isotope exchange of the magmas with the country rocks. Combined with the study of the geological setting for emplacement of the dykes, it is suggested that the magmas forming the intermediate_basic and intermediate_acid dykes in the gold fields are products of the evolution of the cognate magmas. The parent magmas originated from an enriched mantle (δ 18 O SMOW,carbonate :9.2‰、 δ 13 C PDB,carbonate :-4.4‰ and δ 18 O SMOW, magma : 5.8‰), which experienced metasomatism of the lithosphere mantle with the fluids that were generated during the subduction of the oceanic plate and then infiltrated into the lithosphere. Different isotopic effects in the evolution of magma seem to have been the main factors leading to the distinctive features of carbon and oxygen isotopes in the gold fields.

关 键 词：中基性-中酸性脉岩 氧同位素 地球化学 碳同位素 金矿区 成矿作用 

分 类 号：P618.510.2[天文地球—矿床学] P588.13[天文地球—地质学]