This study examines the behavior of trace- and rare-earth elements (REE) in different hydrothermal alteration facies (silicic, advanced argillic and argillic) of Cijulang high-sulfidation epithermal gold deposit, West...This study examines the behavior of trace- and rare-earth elements (REE) in different hydrothermal alteration facies (silicic, advanced argillic and argillic) of Cijulang high-sulfidation epithermal gold deposit, West Java, Indonesia. The results of the study indicate that remarkable differences in the behavior of trace elements and REE are observed in the studied alteration facies. All REE in the silicic facies are strongly depleted. In advanced argillic facies, Heavy rare-earth elements (HREE) are strongly depleted whereas light rare earth elements (LREE) are quite enriched. REE concentrations in the argillic facies show little or no variation with respect to fresh rock counterparts. A strong depletion of REE in the silicic facies is likely to be favored by the highly acidic nature of the hydrothermal fluids, the abundance of complexing ions such as Cl ˉ, F ˉ, and in the hydrothermal solutions and the absence of the secondary minerals that can fix the REE in their crystal structures. An apparent immobility of LREE in advanced argillic facies is possibly due to the presence of alunite. The immobility of REE in the argillic facies suggests the higher pH of the fluids, the lower water/rock ratios and the presence of the phyllosilicates minerals. -展开更多
The Jalilabad Cu(±Au)deposit lies in the central section of the Tarom-Hashjin Metallogenic Belt,in northern Zanjan Province,NW Iran.Mineralization predominantly occurs within quartz-sulfide veins,veinlets,and bre...The Jalilabad Cu(±Au)deposit lies in the central section of the Tarom-Hashjin Metallogenic Belt,in northern Zanjan Province,NW Iran.Mineralization predominantly occurs within quartz-sulfide veins,veinlets,and breccia zones,primarily hosted by the Eocene volcanic and volcaniclastic units of the Karaj Formation.The mineralization trends NW-SE and is influenced by several strike-slip faults.Chalcopyrite and bornite are the principal hypogene sulfides,with chalcocite and covellite representing the supergene stage.The post-ore stage is characterized by brecciated calcite and quartz.Geochemical analyses show that the monzonite intrusion contains SiO_(2)levels ranging from 69.80 to 70.24 wt.%,K_(2)O+Na_(2)O values between 8.10 and 8.15 wt.%,and K_(2)O/Na_(2)O ratios of 1.36 to 1.61.The intrusion is enriched in light rare earth elements(LREEs)and large-ion lithophile elements(LILEs)while being depleted in high-field-strength elements(HFSEs).A low Hf/Sm ratio indicates an orogenic-related magma,and a low Nb/La ratio points to a depleted mantle source.Microthermometric studies of three quartz types reveal moderate to high formation temperatures(195.4-322.7℃)and salinities ranging from 8.10 to 11.82 wt.%NaCl_(equiv).Oxygen isotope data(δ^(18)O_(H2O)O)range from+4.8‰to+8.1‰,suggesting a magmatic origin for the ore-forming fluids,later diluted by meteoric water.Sulfur isotope values(δ^(34)S_(H2S))between−6.0‰and−9.1‰confirm a magmatic source.Fluid mixing and dilution are identified as the primary mechanisms for ore precipitation.Raman spectroscopy enables nondestructive identification of minerals through their unique vibrational peaks.Chalcopyrite(213,280,1304 cm^(−1)),hematite(214,282,469,689,1309 cm^(−1)),goethite(967 cm^(−1)),and quartz(125,198,458 cm^(−1))show distinct spectral fingerprints indicating mineral differentiation,alteration tracking,and structural analysis in geological studies.Based on its geological context,the Jalilabad Cu(±Au)deposit is interpreted as resembling a high-sulfidation epithermal deposit.展开更多
文摘This study examines the behavior of trace- and rare-earth elements (REE) in different hydrothermal alteration facies (silicic, advanced argillic and argillic) of Cijulang high-sulfidation epithermal gold deposit, West Java, Indonesia. The results of the study indicate that remarkable differences in the behavior of trace elements and REE are observed in the studied alteration facies. All REE in the silicic facies are strongly depleted. In advanced argillic facies, Heavy rare-earth elements (HREE) are strongly depleted whereas light rare earth elements (LREE) are quite enriched. REE concentrations in the argillic facies show little or no variation with respect to fresh rock counterparts. A strong depletion of REE in the silicic facies is likely to be favored by the highly acidic nature of the hydrothermal fluids, the abundance of complexing ions such as Cl ˉ, F ˉ, and in the hydrothermal solutions and the absence of the secondary minerals that can fix the REE in their crystal structures. An apparent immobility of LREE in advanced argillic facies is possibly due to the presence of alunite. The immobility of REE in the argillic facies suggests the higher pH of the fluids, the lower water/rock ratios and the presence of the phyllosilicates minerals. -
文摘The Jalilabad Cu(±Au)deposit lies in the central section of the Tarom-Hashjin Metallogenic Belt,in northern Zanjan Province,NW Iran.Mineralization predominantly occurs within quartz-sulfide veins,veinlets,and breccia zones,primarily hosted by the Eocene volcanic and volcaniclastic units of the Karaj Formation.The mineralization trends NW-SE and is influenced by several strike-slip faults.Chalcopyrite and bornite are the principal hypogene sulfides,with chalcocite and covellite representing the supergene stage.The post-ore stage is characterized by brecciated calcite and quartz.Geochemical analyses show that the monzonite intrusion contains SiO_(2)levels ranging from 69.80 to 70.24 wt.%,K_(2)O+Na_(2)O values between 8.10 and 8.15 wt.%,and K_(2)O/Na_(2)O ratios of 1.36 to 1.61.The intrusion is enriched in light rare earth elements(LREEs)and large-ion lithophile elements(LILEs)while being depleted in high-field-strength elements(HFSEs).A low Hf/Sm ratio indicates an orogenic-related magma,and a low Nb/La ratio points to a depleted mantle source.Microthermometric studies of three quartz types reveal moderate to high formation temperatures(195.4-322.7℃)and salinities ranging from 8.10 to 11.82 wt.%NaCl_(equiv).Oxygen isotope data(δ^(18)O_(H2O)O)range from+4.8‰to+8.1‰,suggesting a magmatic origin for the ore-forming fluids,later diluted by meteoric water.Sulfur isotope values(δ^(34)S_(H2S))between−6.0‰and−9.1‰confirm a magmatic source.Fluid mixing and dilution are identified as the primary mechanisms for ore precipitation.Raman spectroscopy enables nondestructive identification of minerals through their unique vibrational peaks.Chalcopyrite(213,280,1304 cm^(−1)),hematite(214,282,469,689,1309 cm^(−1)),goethite(967 cm^(−1)),and quartz(125,198,458 cm^(−1))show distinct spectral fingerprints indicating mineral differentiation,alteration tracking,and structural analysis in geological studies.Based on its geological context,the Jalilabad Cu(±Au)deposit is interpreted as resembling a high-sulfidation epithermal deposit.
