Geology, Geochemistry And Metallogenetic Model In The Fankou Lead Zinc Deposit

This paper integrates and analysizes the geology and geochemistry in the Fankou lead zinc deposit according as the basic geologic data. Since the origin of the Fankou lead zinc deposit has been previously discussed, here I attempt to deal with the source for metallogenic matter, metallogenic envirobment, metallogenetic structure and the origin model.The most important and basic geological feature of the Fankou lead zinc deposit is the regional metallogenetic geological environment. Beginning Devonian, the deposit were originated in the stage of platform troughs. The troughs are dowfaulted basins controlled by synsedimentary structures, NE-trending rift troughs in the Hunan-Guangdong region. The major ores in the deposit all exist in carbonate rocks in middle-upper Devonian, whicth controlled synsedimentary faults. The early metallogenetic processing was dominated by iron sulfides (pyrite). The activation, movement and aggregation of the metallogenetic matter occurred in the stage of diagenesis and metallogenesis. The most important metallogenesis occcured in the stage of the Diwa violent period (late Indochinanian and early Yanshanian). This paper suggests that the Fankou lead zinc deposit is a typical polygeneyic compound ore deposit.Orebody morphology is an intuitive indicator of origin deposits. For instance, a stratiform orebody is probably syngenetic in origin, while a vein orebody must be epigenetic. The morphology of the individual orebody is more complex, including bed-like orebody, lentoid orebody, erose orebody, vein-like orebody and so on. The combined morphology of orebodies is similar to melon and bine. It implies that structure is most important controlled factor for forming and orientation of ores in the Fankou.In regaed to the characteristic of trace element and minar element geochemistry of the well rock, Quren basin was a deoxidizing deposital environment in early metallogenesis. The magmatic process did not participate in forming of the Fankou lead zinc deposit. Dolomitizing had no effect on trace elements for the orebodies. Doleritic veins are made sure of mantle source, which did not mix with upper crust matter.A lot of isotope data about the Fankou lead zinc deposit have been accumulated. When plotted 206Pb/204Pb versus 207Pb/204Pb and 208Pb/204Pb, the data are grouped well above and to right of their stratigraghic model age based on Stacey-Kramers average crust growth curves. Its implying is taken as evidence of a upper crust source for the lead and, presumably, other metals of the deposit. A lot of sulfur isotope data about sulfide ores in the Fankou lead zinc deposit are available. It indicates thatthe sulfur of the mineralizing fluids may have well been derived from stratum sulfur. Comparing and analysizing oxygen isotopes and carbon isotopes between stratum and ores, the author considers that the fluid of the diagenesis and metallogenesis may mainly have been meteoric water. The thermodynamic power, structural network and meteoric water were the most basic factors of the fliud circulation. To summarize, this paper suggests that the forming and evolution of ores in the Fankou deposit related to the multiplicate processes of metallogenesis, repeating and compounding of the metallogenetic processes and the multiplicate controlling factors. Therefore, this paper gives a synthetical model of polygeneyic compound ore deposit for the Fankou lead zinc deposit.