Discovery of seismites in Upper Sinian stratiform lead-zinc deposits in Dadu River valley, Sichuan, China: Implication for ore genesis  

作　　者：LIN Fangcheng1,2 & PAN Guitang2 1. Geoscience College, Chengdu University of Technology, Chengdu 610059, China 2. Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, China 

出　　处：《Science China Earth Sciences》2006年第11期1135-1146,共12页中国科学（地球科学英文版）

摘　　要：A number of lead-zinc sulphide deposits have been discovered in recent years in dolo- mitic rocks of the Upper Sinian Dengying Formation in the Dadu River valley region, Sichuan Province, China. The lead-zinc mineralization is closely associated with a black siliceous exhalite that has been traced over 50 km of strike. This makes Dadu River valley the most extensive stratiform non-ferrous sulphide horizon having been discovered to date in China. In a previous study by the first author (LIN), these deposits were recognised as belonging to the broad spectrum of lead-zinc sedimentary exhala- tive (SEDEX) deposits. In this paper, seismites and seismogenetic structures occurring in close association with the Dadu River valley mineralized zone are described. The close spatial and temporal relationship between the seismites and mineralization provides strong evidence for the hypothesis that the lead-zinc SEDEX deposits formed in direct response to earthquake activities around the Sinian-Cambrian boundary. The earthquakes are postulated to be an effective dynamic mechanism for triggering the upward migration of deep circulating ore fluids along synsedimentary growth faults and their exhalation onto the sea-floor to form the extensive deposits of stratiform lead-zinc sulphide ore.A number of lead-zinc sulphide deposits have been discovered in recent yearsin dolo-mitic rocks of the Upper Sinian Dengying Formation in the Dadu River valley region, SichuanProvince, China. The lead-zinc mineralization is closely associated with a black siliceous exhalitethat has been traced over 50 km of strike. This makes Dadu River valley the most extensivestratiform non-ferrous sulphide horizon having been discovered to date in China. In a previous studyby the first author (LIN), these deposits were recognised as belonging to the broad spectrum oflead-zinc sedimentary exhala-tive (SEDEX) deposits. In this paper, seismites and seismogeneticstructures occurring in close association with the Dadu River valley mineralized zone are described.The close spatial and temporal relationship between the seismites and mineralization providesstrong evidence for the hypothesis that the lead-zinc SEDEX deposits formed in direct response toearthquake activities around the Sinian-Cambrian boundary. The earthquakes are postulated to be aneffective dynamic mechanism for triggering the upward migration of deep circulating ore fluids alongsynsedimentary growth faults and their exhalation onto the sea-floor to form the extensive depositsof stratiform lead-zinc sulphide ore.

关 键 词：seismites  earthquake  lead-zinc deposit  hydrothermal exhalation  Upper SINIAN Dengying Age. 

分 类 号：P618.4[天文地球—矿床学]