地质学报（英文版）2008，Vol.82Issue(4)：811-819,9.
Exhalative Lead-Zinc Deposits in Shallow Sea, Southern Xicheng Belt, Gansu Province
Exhalative Lead-Zinc Deposits in Shallow Sea, Southern Xicheng Belt, Gansu Province
摘要
Abstract
SEDEX-type lead-zinc deposits in the southern belt of the Xicheng Devonian basin, GansuProvince has been already identified. However, the sedimentary environment of the limestone andphilite of the Xihanshui Group within which the lead-zinc deposits occur is littoral and shallow sea.This is different from those in the northern belt such as the Changba-Lijiagou lead-zinc deposits, whichwere formed in deep sea. The reef and bioclastic limestone are widespread in the southern belt.Particularly they are associated with lead-zinc ores and there are no striae and banding but massive ordisseminated structures. It is discovered that the black chimney consists of sphalerite, ankerite, pyriteand galena, in which black, coarse and radial sphalerite occurs as irregularly veins or cylindricafitywith a width of 10-40 cm in the center, and it is surround by fine ankerite and minor celestite withribbon structure. The immediate wall rock of the chimney, reef limestone, was unaltered and theoutside reef and bioclastic limestone were intensively silicified. Those silicified reef and bioclasticlimestone host disseminated lead-zinc ores of the Lnoba and Bijiashan type. It is concluded that theexhalative system occurred in a shallow sea in the Givetian of the middle Devonian. Brine is boiled dueto low pressure, and a great deal of lead and zinc was dispersed in the interface between the limestoneand phyllite and formed a source bed. In the Triassic period, meta-hydrothermai fluids leached andextracted metals from the source bed, and then moved and mineralized in open space such as archesand inverse limbs of anticlines, and formed massive and vein ores such as the Jianyagou andDengjiashan type deposits.关键词
sedimentation-exhalation type, ore-forming model, shallow sea, Qinling, Gansu, ShaanxiKey words
sedimentation-exhalation type, ore-forming model, shallow sea, Qinling, Gansu, Shaanxi分类
天文与地球科学引用本文复制引用
ZHU Xinyou,WANG Dongbo,WEI Zhiguo,QIU Xiaoping,WANG Ruiting..Exhalative Lead-Zinc Deposits in Shallow Sea, Southern Xicheng Belt, Gansu Province[J].地质学报（英文版）,2008,82(4):811-819,9.基金项目
for their supports in this study.This study was funded by the China Geological Surey(No.G1999043200). （No.G1999043200）
