云南都龙锡锌矿床中白钨矿微量元素及稀土元素地球化学

The trace and rare earth elements in scheelites and their implication for the mineralization in Dulong Sn-Zn polymetal ore deposit,Yunnan Province

云南马关都龙Sn-Zn多金属矿床位于滇东南老君山锡锌钨多金属成矿区南部,是我国三大锡石硫化物矿床之一,近年来矿区外围西部-金石坡矿段的地质勘探与找矿,发现矿区深部燕山期隐伏花岗岩外接触带存在大量W(-Cu-Mo)矿化,呈细脉(网脉)状、星点状、团斑状产于碎裂状石榴石-透辉石夕卡岩、节理与裂隙发育的夕卡岩化大理岩及片岩和花岗岩顶部硅化壳接触带.研究表明,其中矿石矿物-白钨矿以富集Sn,Mo,Pb,Zn,Cu为特征,Sr和Ba相对富集,其稀土配分模式为中等向右倾斜曲线,这些微量元素富集与稀土元素元素组成特征与隐伏花岗岩基本一致,仅Eu正异常明显,可能是继承了花岗岩中长石类矿物的Eu正异常特征所致,W等成矿物质主要来源于深部燕山晚期隐伏花岗岩,其矿化应与深部隐伏花岗岩侵入活动过程中的结晶分异作用有关,该成矿阶段,成矿流体具有较高的温度和氧逸度.此外,从矿区深部(靠近隐伏岩体)至地表浅部,矿化类型(W-Fe-Cu-Mo-Sn→Sn-Zn)和夕卡岩类型(无水夕卡岩:石榴石化和透辉石→含水夕卡岩:绿泥石、阳起石、透闪石)均呈有规律变化,其垂直分带特征与典型夕卡岩型矿床较类似.因此,都龙Sn-Zn多金属矿床应属于与燕山晚期花岗岩有关的夕卡岩型多金属矿床,其中层状夕卡岩的形成应为成矿流体顺层交代的结果,矿化类型和围岩蚀变的差异与隐伏岩体距离和控矿构造有关.

As one of the three largest Sn-Zn polymetal ore deposits in China,Dulong ore deposit is located on the southern Laojunshan Sn-Zn-W polymetal mineralization province in south-eastern Yunnan. By geological exploring for the Jinshipo ore block,western of Dulong ore area in recent years, a new mineralization type of W（-Cu-Mo）was discovered. Its ore bodies are hosted in the garnet-diopside skarn and carbonatite with quartz-mica schist of the Middle Cambrian Tianpeng Formation,and the outer contact zones of Later Yanshanian concealed granite,in which the ore mineral-scheelite occur as fine（network）veins,star-like and massive-like. Our research shows that the scheel- ite is character by rich in Sn, Mo, Pb, Zn,Cu, Sr and Ba,and the Chondrite-normalized REE patterns of the scheelite belong to the LREE-rich type, corresponding to that of Later Yanshanian concealed granite except the obvious positive anomaly of Eu,which might inherit the Eu-rich feature of feldspar in granite. It is suggested that the metal logenic material（such as W etc.）main came from the granite, and the W mineralization is related to the crystallization differentiation of the intrusive rock, in which the metallogenic physical chemistry environment belong to a higher temperature and stronger oxidation environment. Moreover, the scheelite, molybdenite and chalcopyrite is main ore mineral of those ore-forming elements （W, Cu, Mo etc.）, and the wall-rock alteration is dominated by garnet and diopside in the deep of ore are. In contrast, the Zn and Sn are the ore-forming elements, which present as sphalerite and eassiterite,and the wall-rock alteration is dominated by chlorite and actinolite in the surface of ore area. The regular mineralization and skarn zoning in vertical mode is similar to that of typical skarn type deposits. It is suggested that Dulong Sn-Zn polymetal ore deposit is a skarn type deposit related to the Yanshanian granite,and the zoned mineralization and wall-rock alteration are controlled by the distance of rock mass.