西藏邦铺钼多金属矿床碳氧同位素组成及意义  

Oxygen and Carbon Isotopic Composition and its Significance of Bangpu Molybdenum Polymetallic Deposit in Tibet

作　　者：周雄[1] 温春齐[2] 费光春[2] 张贻[1] 周玉[1,2] 岳相元[1] 温泉[2] 

机构地区：[1]中国地质科学院矿产综合利用研究所,四川成都610041 [2]成都理工大学地球科学学院,四川成都610041

出　　处：《金属矿山》2014年第1期92-95,共4页Metal Mine

基　　金：国土资源部公益性行业科研专项(编号:201011013);"十一五"国家科技支撑计划项目(编号:2006BAB01A04)

摘　　要：对西藏邦铺钼铜多金属矿床中的灰岩、方解石进行了C、O同位素测定。测试结果表明,早期的灰岩具有相对较高的δ13C V-PDB(3.1‰~4.0‰)、δ18O V-SMOW(5.2‰~12.5‰)和Z值(136.44~141.72),晚期的方解石的δ13C V-PDB(-5.6‰^-3.8‰)、δ18O V-SMOW(1.3‰~5.5‰)和Z值(118.57~120.17)则偏低。δ13C V-PDB-δ18O V-SMOW碳酸盐岩来源判别图解显示碳主要来源于蚀变及再沉积碳酸盐岩,δ13C V-PDB-δ18O V-SMOW流体来源判别图解显示成矿流体中的碳来源于岩浆及碳酸盐岩的溶解作用,但明显混合了大气降水。综合分析认为,早期为同生期成岩环境,后期为埋藏混合水环境,流体中的碳可能主要来源于海相碳酸盐岩的溶解作用,但不排除岩浆岩对碳的贡献。碳氧同位素结果显示,当大气降水强度加大时,δ13C V-PDB向低、负值方向偏移,δ18O V-SMOW发生强烈的负偏移,即氧同位素漂移。The limestone and calcite of Bangpu Mo-Cu polymetallic deposit are surveyed by Carbon, oxygen isotope deter- mination. The results show that there are high carbon （δ13 Cv _ PDB = 3. 1‰-4. 0‰） , oxygen isotope compositions （δ18 Ov -smow = 5.2%0 - 12. 5‰） and carbonate salinity index value of Z （ 136.44 - 141.72） from the early period of limestone ,while low carbon （ -5.6‰- -3.8‰）, oxygen isotope compositions （1.3‰ -5.5‰） and Z value （118.57 - 120. 17） from later peri- od of calcites. δ13 Cv - PDB -δ18 Ov-suow diagram for the carbonate source shows that carbon mainly originates from the alteration of sedimentary carbonate rocks δ13 Cv - PDB -δ18 Ov- SMOW diagram for the source of the fluid shows that carbon in the ore-forming fluid mainly comes from magma and dissolution of carbonate rocks which obviously mixed atmospheric precipitation. It is con- cluded that it is the syngenetic diagenetic environment during the early period while buried mixed water environment during the later period. Carbon in ore-forming fluid was mainly derived from the dissolution of marine carbonate formation, but magmatic rock is also an important factor of carbon formation. Carbon and oxygen isotope results shows that when rainfall intensity in- creased,δ13 Cv -PDB shift to a low and negative direction and δ18 Ov- SMOW with a negative excursion which means isotope excur- sion.

关 键 词：碳氧同位素 溶解作用 钼铜多金属矿床 邦铺 

分 类 号：P597[天文地球—地球化学]