摘要
月山地区矽卡岩型和热液脉型铜矿床氢、氧、硫、铅、碳和硅同位素组成及演化的特征显示，区内具工业价值铜矿床的成矿物质主要由闪长质岩浆经熔－流分离作用提供，主要成矿阶段的成矿热液以（广义）岩浆水为主，成矿中晚期大气降水混入量逐渐增多，三叠系和部分前三叠系提供了部分硫源和少量成矿物质。
The Yueshan area in Anhui Province is an important part of the concentrated mineralization area in the Middle and Lower Yangtze Valley. There are two types of copper deposits in Yueshan area:skarn copper deposits and hydrothermal vein ones. Based on the five models of δ 18 O δD isotope evolutional mechanism proposed by this study and the hydrogen and oxygen isotope compositions of each mineralization stage of the two types of copper deposits, it is concluded that the ore forming materials of the major ore deposits precipitated from magmatic water and/or magmatic waters with a complex evolutional history such as shifted or evolutional magmatic water. The two types of copper deposits are the products of the comagmatic hydrothermal system that evolved in different geochemical environments. The ore forming solutions of the large size copper deposits in the Middle and Lower Yangtze Valley were mainly derived from magmatic waters, and those of the small to medium ones seemed to be mixed solutions of magmatic and meteoric waters. It is suggested that when the proportion of meteoric water exceeds 30%, there will be no mi neralization of industrial value. The δ 34 S values of the skarn ore deposits and the vein deposits are -11 25‰～ +19 74‰ and +4 2‰～+8 7‰, respectively. The varying disequilibria of the solutions were caused by the variation in sulfur isotope composition of the sources and the extent of water rock interaction instead of by the change in physicochemical conditions. This paper proposes for the first time six models for the transferring of sulfur from sources into hydrothermal solutions. The results suggest that sulfur of skarn ore deposits was from magma (78%), pre Triassic clastic sedimentary rocks and Triassic carbonate strata that contain gypsum (salt) beds, whereas sulfur of the vein deposits was from magma (79‰～97.7%) and carbonate strata with gypsum (salt) beds. The mixing was caused by water rock interaction. The regional lead mixing model of the copper deposits in Yueshan can be mathematically expressed as ( 207 Pb/ 204 Pb) m=-0.1839( 208 Pb/ 204 Pb) m+3.2986/ 204 Pb m+2.7679(r=0 9836).The two types of copper deposits related to the Yueshan intrusion contain mixture of magmatic lead, upper crustal lead and Triassic sedimentary lead, whereas the vein ore spots related to the Zongpu and the Wuhen intrusions have lead from magma, sedimentary rocks and the upper crustal units. Studies on δ 13 C and δ 30 Si of these copper deposits give similar conclusions. It is concluded that the ore forming materials in Yueshan mainly came from the dioritic magma through melt fluid partition. Triassic and pre Triassic strata provided some sulfur and a small amount of ore forming materials, and the water rock interaction played an important role in copper mineralization.
出处
《矿床地质》
CAS
CSCD
北大核心
1996年第4期341-350,共10页
Mineral Deposits
基金
"攀登"项目
国家教委博士点基金
关键词
同位素地球化学
成矿作用
铜矿床
isotope geochemistry, mineralization, copper deposit, Yueshan area
