Abstract

Results are given of a detailed study of certain geologic features of the Pb-Zn deposit located at Daliangzi, Sichuan Province, China. The Daliangzi Pb-Zn deposit is strata bound in carbonate rocks. A systematic study of lead and sulfur isotopes, and a cluster and correlation analysis of trace elements (including rare earth elements) in the ores and the surrounding rocks, shows that mineralization was derived from several sources. A study of the hydrogen and oxygen isotopes of the fluid inclusions in sphalerite indicates that the ore-forming fluid belonged to a Ca (super +2) -Mg (super +2) -Cl (super -) -HCO (super -) 3 type of weak acidic to near-neutral pH solution whose salinity was about 4 wt percent NaCl. The fluid had a meteoric source. The ore was formed at a depth of about 1 km at a temperature of about 150 degrees to 200 degrees C during the main stage of ore deposition.From a comparison between the lead and sulfur isotopes and a study of the metallic complex solubilities, it appears that when hot solutions were passing through the mineralized area the metals and sulfur species were not transported in the same solution. The metals were moved as chloride complexes such as PbCl (super -) 3 , ZnCl (super -) 3 , and ZnCl 2 . The metal-bearing solution moved along deep faults to low-pressure zones, where the metal ions reacted with reduced sulfur and were precipitated as sulfides. The textures of the minerals were controlled by the rate at which the reduced sulfur was supplied.

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