Mesozoic Multi-phase Magmatism and Gold Mineralization in the Early Precambrian North China Craton,Eastern Hebei Province,China:SHRIMP Zircon U-Pb Evidence
会议名称:《中国科学院地质与地球物理研究所2008学术年会》
会议日期:2009年
学科分类:070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金:supported by the Ministry of Science and Technology of China(grant No.2006CB403504) the National Natural Science Foundation of China(grant No.40473030) the Department of Land and Resources of Hebei Province (grant No.2005-038) the China/Western Anstralia Economic and Technology Fund
摘 要:The early Precambrian North China craton(NCC) in eastern Hebei Province(also known as the Jidong area) was intruded by granitic batholiths and plutons spatially associated with gold deposits. No consensus has been reached regarding timing and tectonic setting of the gold deposits,chiefly due to the lack of reliable geochronological *** gold deposits in the district are localized by NE-striking faults within granite plutons and/or nearby Archean amphibolites,as well as in Proterozoic sedimentary *** mineralizations in the area are characterized by quartz(±albite) veinand sulfide-disseminated styles;both types of ores have relatively low sulfide contents(10 vol%) and similar sulfide mineral assemblages dominated by pyrite + chalcopyrite + pyrrhotite + galena + sphalerite,locally with molybdenite,tellurides,and *** alterations around the gold lodes include K-feldspathization,sericitization,silicification,chloritization,and *** fluid inclusion data from all the deposits of the district show that the mineralizing fluids are characterized by relatively high salinities(3 to 17 wt%NaCl equiv.),HO-CO±CH,N solutions, with CO contents in the inclusions ranging from 5 to 40 mol%.Fluid inclusion homogenization temperatures are between 240 and 400℃,and estimates of the trapping pressures vary significantly from 0.5 to 3.7 *** isotope(O,H,S,C,and Pb) data from these deposits indicate a major magmatic component in the mineralizing fluids and the ore-forming materials,with a partial contribution by Archean host rocks,suggesting that these deposits are basically intrusion-related. SHRIMP zircon U-Pb geochronology of the gold-hosting granitic intrusions,in combination with previous Ar-Ar and Rb-Sr dates on hydrothermal minerals(e.g.,sericite),indicates that there was no Archean gold mineralization,but instead suggests that at least three episodes of granitic magmatism and associated gold mineralization took place during the Mesozoic.