摘要
老厂矿床是昌宁-孟连缝合带内唯一大型矿床,本文报道了老厂矿床Ag-Pb-Zn矿体中Ⅰ号矿体群下部块状矿体和上部网脉状矿体的方解石C-O同位素组成,以及Ⅰ、Ⅱ、Ⅳ三个矿体群内闪锌矿的Zn同位素组成。Ⅰ号矿体群下部块状矿体和上部网脉状矿体方解石δ^(13)C_(PDB)的范围分别为-6.17‰~2.71‰和-2.18‰~3.87‰,δ^(18)O_(PDB)的范围分别为-19.57‰~-17.23‰和-22.10‰~-16.21‰;计算获得对应成矿流体的δ^(13)C_(CO_(2))为-6.16‰~1.53‰和-2.39‰~6.43‰,δ^(18)O_(H_(2)O)分别为1.62‰~7.62‰和4.36‰~16.92‰,通过与岩浆CO_(2)(δ^(13)C=-2‰~-8‰)和围岩灰岩(δ^(13)C=-1.6‰~4.0‰)的δ^(13)C值相比较,指示块状矿体成矿流体中的碳主要来自岩浆,网脉状矿体成矿流体中的碳则主要来自围岩,说明老厂矿床深部水岩反应较强。10件闪锌矿的δ^(66)Zn和δ^(68)Zn值分别为0.17‰~0.25‰和0.33‰~0.49‰,与VMS型矿床以及现代海底热液流体的Zn同位素组成重合,不同标高均一的Zn同位素组成寓示老厂矿床Ag-Pb-Zn矿体中闪锌矿形成过程中几乎未受到温度、分馏和微生物作用的影响,可以直接反映金属源区的Zn同位素组成,揭示老厂矿床Ag-Pb-Zn矿体为VMS成因,成矿金属主要来自于下石炭统海底火山作用。
The Laochang deposit is the only large ore deposit in the Changning-Menglian suture zone.In this study,the C-O isotopic compositions of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰore bodies in Laochang Ag-Pb-Zn ore bodies and the Zn isotopic compositions of sphalerites from No.Ⅰ,Ⅱ,Ⅳore bodies are investigated.The range of δ^(13)C_(PDB) of calcites from the lower massive ore bodies and the upper stockwork ore bodies of No.Ⅰore bodies is-6.17‰~2.71‰and-2.18‰~3.87‰,respectively,and the range of δ^(18)O_(PDB) is-19.57‰~-17.23‰ and-22.10‰~-16.21‰,respectively.Theδ^(13)C_(CO_(2)) of the corresponding ore-forming fluids are calculated to be-6.16‰~1.53‰ and-2.39‰~6.43‰,respectively,and the δ^(18)O_(H_(2)O) are calculated to be 1.62‰~7.62‰ and 4.36‰~16.92‰,respectively.By comparison with the δ^(13)C of magmatic CO_(2)(δ^(13(C=-2‰~-8‰)and wall-rock limestone(δ^(13)C=-1.6‰~4.0‰),it indicates that the carbon in the ore-forming fluids of massive ore bodies mainly comes from magma,while the carbon in the ore-forming fluids of stockwork ore bodies mainly comes from limestone,which further shows that there is strong water-rock reaction in the deep part of Laochang deposit.The δ^(66)Zn and δ^(68)Zn values of ten sphalerites are 0.17‰~0.25‰ and 0.33‰~0.49‰,respectively,which coincides with the Zn isotopic compositions of VMS deposits and modern submarine hydrothermal fluids.The homogeneous Zn isotopic compositions at different elevations implies that the Zn isotopic compositions of sphalerite from Ag-Pb-Zn orebodies in Laochang deposit are almost unaffected by temperature,fractionation and microbial action.And it can directly reflect the Zn isotopic compositions of the metal source,revealing the genesis type of the Laochang Ag-Pb-Zn ore body as VMS-type,and the metallogenic metal mainly comes from the Lower Carboniferous submarine volcanism.
作者
唐鑫
陈福川
张鹏飞
李龚健
赵枫
陈威
TANG Xin;CHEN FuChuan;ZHANG PengFei;LI GongJian;ZHAO Feng;CHEN Wei(State Key Laboratory of Geological Process and Mineral Resources,China University of Geosciences,Beijing 100083,China;Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,China;School of Geogrophy and Resource Science,Neijiang Normal University,Neijiang 641100,China;Chengtun Mining Group Co.Ltd,Xiamen 361012,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第1期143-156,共14页
Acta Petrologica Sinica
基金
国家重点基础研究发展计划(2015CB452606)
国家自然科学基金重大研究计划(91855217)和国家自然科学基金青年项目(41902070)联合资助。
