Studies of Geology, Mineralisation and Fluid Involved in Lead and Zinc Indice of the Dareh Qileh (Northeast of Aligudarz(

Abstract

The tectono-magmatic evolution of NW Iran records the Paleozoic–early Mesozoic formation and consumption of the Neo-Tethys Ocean. Debate focus on how the regionally-distributed basement exposures and their diverse evolution setting are connected in the division of Iranian tectonic basins. The oldest sediments that are exposed in the study area are the Upper Triassic-Jurassic sediments and sandstones of the region have been altered by the Late Cimmerian phase to the level of the greenschist facies (biotite zone). The structural elements present in the area include faults, folds, joints, and plates. The Upper Triassic-Jurassic sediments and sandstones of the region have been altered by the Late Cimmerian phase to the level of the greenschist facies (biotite zone). The degree of alteration of the rocks in question, based on microscopic studies, is at the level of the albite, epidote-hornfels facies. The mineralization in this deposit has formed in the form of veins and lenses with layering and along the quartz veins. The mineralogy of the mineral includes sphalerite, galena, pyrite and to a very small extent chalcopyrite. In studies of the fluids involved, the homogenization temperature of the fluid inclusions varied in the temperature range between 115-215 degrees Celsius, and based on studies conducted on the samples, the salinity of the fluids involved is equal to 10 to 22 percent by weight equivalent to common salt. The density of the fluids also varies from 0.8 to more than 0.9. According to microthermometry studies, the evolution of the mineralizing fluid was due to mixing with surface waters in the mineralizing fluid, which led to the deposition of the mineral. It can be said that the mineralizing fluid shows a range of characteristics of basin brines and atmospheric fluids. In general, studies show that the deposition of metallic minerals occurred simultaneously from the hydrothermal fluid transported to the region and deposition along the vein quartz left by these fluids. According to the results of the studies and based on the tectonic environment, the type of host rock, the homogenization temperature and the salinity of the fluid interlayers, the deposit can be considered similar to the Irish-type zinc-lead deposits. Our study provides an evolution model that integrates the various complexes of NW Iran into a common Late Cambrian to Late Triassic evolution of the neo-Tethys.