吉林延边地区斑岩型－浅成热液型金铜矿床

PORPHYRY-EPITHERMAL COPPER-GOLD DEPOSITSIN YANBIAN AREA, JILIN PROVINCE

吉林延边地区为我国滨太平洋带的一个重要的金属成矿区。与中生代火山－次火山侵入活动有关的斑岩型。浅成热液型矿床在时空上、成因上构成一个成矿系列。本文选择四个代表性矿床（小西南岔、闹枝、五凤和刺猬沟），较详细地介绍它们的成矿地质背景、矿床地质特征、流体包裹体、稳定同位素及成矿机制等。通过这些矿床的描述，勾画出一幅从中生代火山盆地边缘的隆起带的斑岩型矿床（小西南岔）→中生代火山盆地内部的断隆块的斑岩－浅成热液过渡型矿床（闹枝）→中生代火山盆地内部断裂带的浅成热液型矿床（五凤和刺猬沟）的全景。

Yanbian area of Jilin is an important metallogenic province in the circum-Pacific belt ofChina. Spatially and genetically, the porphyry-epithermal copper-gold deposits related toMesozoic volcanic-subvolcanic-intrusive activities make up a metallogenic series. Exemplifiedby four typical ore deposits , namely , Xiaoxinancha , Naozhi , Wufeng and Ciweigou , the pre-sent paper deals with geological characteristics and ore-forming mechanism of this metallogenic.series. The Xiaoxinancha copper-gold deposit , a deposit of porphyry type, occurs in the up-warped zone on the margin of the Mesozoic volcanic basin ; mineralization is controlled by con-cealed Yanshanian granite porphyry and diorite porphyrite dike, with the major mineralizedbodies present in Variscan diorite at the top of the concealed granite porphyry body and inLower Paleozoic biotite felsic hornfels ; the temperature and the salinity of the ore fluids vary inthe range of 100￣550℃ and 27.9￣56 wt % NaCl respectively , suggesting that the ore fluidsare mainly magmatic water, mixed with some subordinate meteoric water. The Naozhi gold(copper) deposit , being of porphy-ryepithermal transitional type ,occurs in the uplifted districtwithin the Mesozoic volcanic basin ; mineralization is controlled jointly by faults and Yanshani-an subandesite porphyrite , with the major mineralized bodies existent in Variscan granodiorite ;the temperature and the salinity vary in the range of 150￣450℃ and 0.8￣50 wt % NaCl re-spectively, implying that both magmatic water and meteoric water make up remarkable pro-portion , The Wufeng and Ciweigou gold deposits, belonging to epithermal type, occur in theinterior of the Mesozoic volcanic basin; mineralization is controlled by faults, and the majormineralized bodies exist in Mesozoic volcanic rocks, with the deep mineralized body extendingto the basement rock ;the temperature and the salinity of ore fluids are 100￣400℃ and 0. 2￣5. 5 wt % NaCl respectively, suggesting that meteoric water plays a dominant role and mag-matic water is less important ; the metallogenic position corresponds to the discharge system ofthe geothermal spring.