THE EXHALATIVE SEDEMENTARY MINERALIZATION AND ITS IMPLICATIONS FOR THE EXPLORATION IN LANPING BASIN ,YUNNAN,CHINA

Both Caizidi and Qingdianwan Pb-Zn deposits are in northeast of Lanping Basin, which, located in Yunnan province, south-west China, is well known to the world for the famous Jinding Zn-Pb deposit. Through detailed geological and petrographical investigation in the two deposits, a lot of classic texture and structure of the Pb-Zn ores are indentified, which are similar to those formed during exhalative sedimentary mineralztion, such as lamellar structure, soft sedimentary of pyrite, syngenetic slump structure, framboidal pyrite, concentric ring structure of pyrite and sphalerite etc. Analyses of the mineralzied elements indicate that there exists an element zoning sequence, which is the same as that in the SEDEX Pb-Zn deposit. Combine with the comprehensive analysis of the main element, trace element, rare element and sulfur isotope geochemistry of the two deposits, the conclusion is made that the Pb-Zn metallogenesis was related to the exhalative sedimentation in the intracontinent rift enviroment of the lanping basin at late triassic, not to the hydrothermal mineralization during thrusting movement in the plaeocene. In addition to add a new type of deposit to Lanping Basin, the indentification of the SEDEX deposit is also valuable to guide the exploration of Pb-Zn deposit in the basin and helpful to the comprehension of the regional ore-forming mechanism.