Chloritisation along the Thanewasna shear zone, Western Bastar Craton, Central India: Its genetic linkage to Cu–Au mineralisation

Dora, M. L.; Randive, Kirtikumar

doi:10.1016/j.oregeorev.2015.03.018

Cited by 32 publications

(12 citation statements)

References 51 publications

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“…Chlorite thermometer was used in gold deposits to assist the constraints on the metallogenic temperature [9,10,41]. Typically, basal spacing d 001 of chlorite shows a positive correlation with its crystallographic temperature [42].…”

Section: Physicochemical Conditions Of Chloritementioning

confidence: 99%

Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers

Sun

Zhang

et al. 2019

Minerals

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The Zhengchong gold deposit, with a proven gold reserve of 19 t, is located in the central part of Jiangnan Orogenic Belt (JOB), South China. The orebodies are dominated by NNE- and NW- trending auriferous pyrite-arsenopyrite-quartz veins and disseminated pyrite-arsenopyrite-sericite-quartz alteration zone, structurally hosted in the Neoproterozoic epimetamorphic terranes. Three stages of hydrothermal alteration and mineralization have been defined at the Zhengchong deposit: (i) Quartz–auriferous arsenopyrite and pyrite; (ii) Quartz–polymetallic sulfides–native gold–minor chlorite; (iii) Barren quartz–calcite vein. Both invisible and native gold occurred at the deposit. Disseminated arsenopyrite and pyrite with invisible gold in them formed at an early stage in the alteration zones have generally undergone syn-mineralization plastic-brittle deformation. This resulted in the generation of hydrothermal quartz, chlorite and sulfides in pressure shadows around the arsenopyrite and the formation of fractures of the arsenopyrite. Meanwhile, the infiltration of the ore-forming fluid carrying Sb, Cu, Zn, As and Au resulted in the precipitation of polymetallic sulfides and free gold. The X-ray elements mapping of arsenopyrite and spot composition analysis of arsenopyrite and chlorite were carried out to constrain the ore-forming physicochemical conditions. The results show that the early arsenopyrite and invisible gold formed at 322–397 °C with lgf(S2) ranging from −10.5 to −6.7. The crack-seal structure of the ores indicates cyclic pressure fluctuations controlled by fault-valve behavior. The dramatic drop of pressure resulted in the phase separation of ore-forming fluids. During the phase separation, the escape of H2S gas caused the decomposition of the gold-hydrosulfide complex, which further resulted in the deposition of the native gold. With the weakening of the gold mineralization, the chlorite formed at 258–274 °C with lgf(O2) of −50.9 to −40.1, as constrained by the results from mineral thermometer.

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Section: Physicochemical Conditions Of Chloritementioning

confidence: 99%

Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers

Sun

Zhang

et al. 2019

Minerals

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“…Multiple episodes of Precambrian mafic magmatism formed dyke swarms, mafic volcanic rocks, and mafic dykes (Ramachandra, Mishra, & Deshmukh, 1995;Challapathi Rao et al, 2011;Srivastava & Gautam, 2009). The Western Bastar Craton occurring along the northern shoulder of Godavari Graben is dotted with numerous occurrence of base metal mineralization confined to NNW-SSE-to N-S-trending brittle shear zone/fault zone (Dora & Randive, 2015;Sashidharan, 2007).…”

Section: Geological Frameworkmentioning

confidence: 99%

Characterization of copper ± (gold) vein‐type mineralization along terrain boundary fault, Dubarpeth in Central India: Constraints from fluid inclusion, stable isotope, and in situ trace element geochemistry of sulphides

et al. 2019

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We present the findings on in situ trace element geochemistry of sulphides by LA-ICPMS, sulphur isotope, and hydrothermal fluid evolution of copper ± gold mineralization at Dubarpeth, Central India. Mineralization is associated with chloritizedsilicified alteration zones, structurally localized along the terrain boundary fault between Archean TTG quartz diorite (2.5 Ga) of Western Bastar Craton and Paleo-Mesoproterozoic cover sediments of Pranhita-Godavari (PG) Valley. Studies reveal that the Cu ± Au mineralization occurs in the form of dissemination, stringers, and veins along the microfaults and fractures. We infer three stages of mineralization based on the field observations and petrography studies. The early stage is characterized by the quartz-pyrite-chalcopyrite assemblage, while the middle stage is represented by quartz-chlorite-chalcopyrite ± pyrite. Calcite ± epidote is conspicuous in the late stage. Fluid inclusion microthermometry and Raman spectroscopy studies indicate that the early-stage veins are mainly aqueous rich, mixed carbonicaqueous, and minor vapour-rich aqueous inclusions. FIs in the early stage displayed evidence of vein formation during episode of fluid immiscibility with the homogenization temperatures and salinities up to 259°C and 27 wt.% NaCl equiv., respectively, indicating initial ore-forming fluids of moderate temperature, moderate to high salinity in H 2 O-CO 2 -NaCl systems. Copper mineralization stage is liquid-and vapour-rich (H 2 O-CO 2 -CH 4 + N 2 ) aqueous inclusions, with homogenization temperatures of 174-221°C and salinities of 6.37 to 13.9 wt.% NaCl equiv. This temperature range has been further supported by empirical chlorite thermometry based on Fe/Mg, Al IV , and Al V . The sulphur isotope values of pyrite and chalcopyrite showed δ 34 S interval of 2.29‰ to −10.85‰, characteristic of highly oxidized nature of the fluids and attributing sulphur source to magmatic origin. The ore-forming fluids gradually became SO 2− 4 enriched and relatively oxidized during Cu mineralization. High Co-Ni trace element signatures of pyrite by LA-ICPMS substantiate this observation, further indicating remobilization from a magmatic-hydrothermal fluid. The presence of CH 4 favours either a source of deep crustal nature or a mantle for the ore-

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“…The study area comprises of 1000-1500 m thick deformed and undeformed Proterozoic sedimentary sequence, exposed over 20 km strike length, between Pomburna and Dhaba outlines bounded by Archaean basement rocks in the east and fault controlled linear Gondwana rocks in the west (figure 2A). The Archaean rocks exposed in the east include hornblendegneiss, quartzo-feldspathic gneiss, charnockite, meta-pyroxenite and gabbro intruded by undeformed Mesoproterzoic granite (Sashidharan and Ganvir 2004;Mukharjee et al 2007;Sashidharan 2007;Dora 2012;Dora and Randive 2015;Rao et al 2017). Sedimentary sequences are similar to Devalmari and Somanpalli Groups, and comprise a cyclic arenite-pelite-carbonate association, exposed near Dongargaon, Gondpipri, Gojoli, Dubarpet, Chintal Dhaba, Kimara, Dewada Khurd, Dongarhaldi and Jam Tukum (figure 2A).…”

Section: Geology Of the Dhaba-pomburna Areamentioning

confidence: 99%

Petrography and geochemistry of the Proterozoic sandstones of Somanpalli Group from Pomburna area, Eastern Belt of Pranhita–Godavari Valley, central India: Implications for provenance, weathering and tectonic setting

et al. 2018

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In this paper, we, for the first time, report geochemistry of sandstone from Somanpalli Group from Pomburna area in the Eastern Belt of Pranhita-Godavari (PG) Valley, central India and studied to infer their provenance, intensity of paleo-weathering and depositional tectonic setting. Petrographic study of sandstones show QFL modal composition of arenite. Chemical results show high SiO 2 and CIA but lower Al 2 O 3 , TiO 2 , Rb, Sr, K 2 O indicating mixed sources. Major elements chemistry parameters such as, K 2 O/Al 2 O 3 ratio and positive correlation of Rb with K 2 O, reflects a warm and humid climate for study area. The tectonic discrimination plots (SiO 2 /20-K 2 O+Na 2 O-TiO 2 +Fe 2 O 3 +MgO; K 2 O/Na 2 O vs. SiO 2 ; Th-Sc-Zr/20) indicate dominantly passive margin and slight active tectonic setting. Concentrations of Zr, Nb, Y, and Th are higher compared to the UCC values and the trends in Th/Cr, Th/Co, La/Sc and Cr/Zr ratios support a felsic and mafic source for these sandstones and deposition in passive margin basin. Chondrite normalized REE pattern reflects LREE depletion, negative Eu anomaly and flat HREE similar to UCC, felsic components. ICV value (0.95) also supports tectonically quiescent passive margin settings. CIA values (74) indicate high degree of chemical weathering and warm and humid paleoclimatic condition.

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Chloritisation along the Thanewasna shear zone, Western Bastar Craton, Central India: Its genetic linkage to Cu–Au mineralisation

Cited by 32 publications

References 51 publications

Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers

Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers

Characterization of copper ± (gold) vein‐type mineralization along terrain boundary fault, Dubarpeth in Central India: Constraints from fluid inclusion, stable isotope, and in situ trace element geochemistry of sulphides

Petrography and geochemistry of the Proterozoic sandstones of Somanpalli Group from Pomburna area, Eastern Belt of Pranhita–Godavari Valley, central India: Implications for provenance, weathering and tectonic setting

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