摘要
百炉沟矿床是近年来在盛产斑岩-矽卡岩型钼矿床的河南栾川地区新发现的一处铅锌矿床,位于豫西南牛心剁穹状背斜之西侧,与栾川地区的南泥湖、三道庄、上房沟、马圈等斑岩型及斑岩-矽卡岩型钼矿床相毗邻。矿体呈脉状、板状产在中元古界变质碳酸盐岩-碎屑岩层中,受NWW向层间断裂构造控制。矿石由闪锌矿、方铅矿、黄铁矿、石英、方解石等矿物组成。矿石中石英和闪锌矿所捕获的原生流体包裹体有富液体气液两相包裹体、富气体气液两相包裹体、纯气体包裹体、含子矿物三相包裹体等4种类型,邻近分布,其均一温度相近,表明成矿过程中可能存在流体沸腾作用。气液两相包裹体的均一温度为180～327℃,以中温(250～260℃)为主;盐度w(Na-Cleq)为4.0%～14.0%,以5.0%～9.0%为主;依据均一温度峰值所对应的压力(38.94～44.87MPa),求得成矿深度为1.44～1.66km。表明该矿床明显具有浅成、中温、低盐度热液成矿的特征。单个流体包裹体的气相成分至少有纯H2O蒸汽、N2+CO2+CH4、N2+CO2和N2+CH4等4种组合。矿石中石英和方解石内包裹体水的δDV-SMOW为-76‰～-90‰,方解石的δ13CV-PDB为-0.44‰～1.80‰,选取所对应的流体包裹体均一温度,计算得到包裹体水的δ18O水为2.51‰～10.96‰,反映出成矿流体的主体为岩浆热液。矿石中硫化物的δ34SV-CDT为-1.2‰～10.9‰,其峰值(1‰～2‰)与该地区斑岩型钼矿床中的硫化物相近,指示其具有岩浆来源硫的特征。矿石中硫化物206Pb/204Pb=17.552～18.426,207Pb/204Pb=15.451～15.5794,208Pb/204Pb=38.264～39.637,反映出成矿金属主要来自于岩浆,有少量地层岩石铅的加入。百炉沟铅锌矿床应属受层间构造控制的中温岩浆热液充填-交代矿床。
The Bailugou lead-zinc deposit,a newly-discovered ore deposit in Luanchuan area,Henan Province,is well-known for its porphyry-skarn type molybdenum ore bodies. It is hosted in the west limb of the Niuxinduo dome-like anticline,and is adjacent to the Nannihu,Sandaozhuang,Shangfanggou and Majuan porphyry-skarn type molybdenum deposits in this area. Ore bodies assume veinlike form and are hosted in Mesoproterozoic metamorphic carbonate-clastic rocks,apparently controlled by NWW-trending interlayer fractures. Ores mainly consist of sphalerite,galena,pyrite,quartz and calcite. Primary fluid inclusions trapped in quartz and sphalerite can be divided into four types：liquid-rich two-phase inclusions,gas-rich two-phase inclusions,pure gas inclusions and daughter-mineral bearing three-phase inclusions. These four types of inclusions are trapped in the same stage minerals,assume close distribution,and have similar homogenization temperatures,suggesting that boiling might have happened during mineralization. Thermometry of gas-liquid inclusions gives a range of homogenization temperature between 180 ℃ and 327 ℃ with the peak near mesothermal temperature （250 ℃ to 260 ℃）,and a range of salinity 〔w（NaCleq）〕 from 4.0% to 14.0% （mostly between 5.0% and 9.0%）. Using the pressure of the peak homogenization temperature （38.94 MPa to 44.87 MPa）,the authors estimated that the mineralization depth lies between 1.44 km and 1.66 km. It is thus held that mesothermal temperature,low salinity and shallow mineralization depth characterize the Bailugou lead-zinc deposit. Laser Raman Spectrometer analysis shows that gas phase of single inclusions includes at least four types：pure H2O vapor,N2＋CO2＋CH4,N2＋CO2 and N2＋CH4. δDV-SMOW values of fluid inclusion water in gangue minerals quartz and calcite are-76‰ to-90‰,δ^13CV-PDB of gangue calcite are-0.44‰ to 1.80‰,and calculated δ^18Owater of fluid inclusion water using homogenization temperature are 2.51‰ to 10.96‰,suggesting that ore-forming fluids are mainly magmatic solution. δ^34SV-CDT values of ore sulfides are from-1.2‰ to 10.9‰ and have a peak （1‰ to 2‰） very close to the values of sulfides from the porphyry type molybdenum deposits in this area,implying a magmatic sulfur origin. Sulfides in ores have ^206Pb/^204Pb ratios 17.552～18.426,^207Pb/^204Pb ratios 15.451～15.5794 and ^208Pb/^204Pb ratios 38.264～39.637,suggesting that the metallogenic metals were mostly derived from porphyries in this area with the participation of a certain amount of stratigraphic metals. The Bailugou lead-zinc deposit is a magmatic mesothermal filling-metasomatic type ore deposit controlled by interlayer fractures.
出处
《矿床地质》
CAS
CSCD
北大核心
2010年第5期810-826,共17页
Mineral Deposits
基金
地质过程与矿产资源国家重点实验室开放基金(GPRM200832)
高等学校学科创新引智计划(B07011)
国家自然科学基金(40772061
40472054)
长江学者和创新团队发展计划(IRT0755)的联合资助
关键词
地质学
地球化学
流体包裹体
H、C、O、S、Pb同位素
铅锌矿床
岩浆热液
百炉沟
栾川
河南
geology
geochemistry
fluid inclusion
H
C
O
S and Pb stable isotopes
lead and zinc deposit
magmatic-hydrothermal solution
Bailugou
Luanchuan
Henan Province
