QE344 : Mineralogy, geochemistry and genesis of the Golcheshmeh copper deposit, Northeast of Sabzevar
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2017
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Abstarct: Sabzevar ophiolites are one of the upper Cretaceous ophiolites which are located in the northern of the crust of the central Iranian continent. This ophiolite collection contains a development mantle sequence: harzburgite, lerzolite, donit with chromite that discontinued by diabetic to gabbro dikes. The crustal sequence of cumulus ultramafics and mafics, gabbros, pillowlavas with upper Cretaceous-paleocene sediments. The Golcheshmeh copper deposit is located in 30 km northeast of sabzevar, in the sabzevar subzone, in the North sabzevar ophiolitic sequence and within the Cretaceous sedimentary volcanic rocks. The host sequence of the deposit contain four mineral horizons from bottom to top: OH1: Semi massive to massive sulfide with brecciated texture with underliad silica- sulfide stringer zone, within gabbro and basalt host rocks (Golcheshmeh deposit), OH2: Sulfide stringer zones within gabbro and basalt (mineral occurrence 3), OH3: Massive sulfide with underneath silica-sulfide stringer zone in gabbro and basalt, and tuffaceous-cherty Mn-Fe unit at top (mineral occurance 2), OH4: Massive sulfide with underneath silica-sulfide stringer zone in gabbro and basalt, and exhalative sediment-bearing chert and Fe-Mn (exhalites) at top (minerals occurrence 1). According mineralogy and texture studies and construction, in the Golcheshmeh deposit, three different ore-bearing facies can distinguished: 1) quartz-sulfide vein-veinlets facies or feeder, 2) Semi massive to massive sulfide facies with brecciated to vein-veinlets texture, and 3) Fe-Mn sedimentary-exhalative unit. Primary minerals in the mineral horizon include, respectively, pyrite, chalcopyrite, magnetite, bornite, Sphalerite, pyrolusite, psilomelane and secondary malachite, covellite, chalcocite, digenite, goethite, hematite and other iron and manganese oxides. Gangue minerals mainly consist of chlorite, sericite and quartz. Wall rock alterations include chlorite, epidote and silicic-sericitic. Geochemical studies in mineralized facies indicate that the amount of Ag, As, Ba, Sr and Ce elements. In sedimentary-exhalative facies was higher than massive and vein-veinlet facies. The content of element for the second horizon are, 2.92, 81.06, 58.99, 25.33 ppm and 212.51 and for third horizone 29.86, 44.27, 15619.5, 4.7 and 3801.57 ppm, respectively. Frequency of copper in the massive facies from exhalite and stringer facies is higher than that in the massive facies in the second horizon of mineralization get to 998.94 ppm. According to the essential charactristics of mineralization, the Golcheshmeh deposite can classified in category of volcanic massive sulfide (VMS). The formation of this deposite is justified by buoyant plume model due to exhalite-hydrotermal activities with mafic volcanic activities in the ocean floor expansion.
Keywords:
#Volcanic-sedimentary sequence #copper #volcanogenic massive sulfide #upper cretaceous #Golcheshmeh #Sabzevar subzone Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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