Prospectivity of Mesoproterozoic magmatism in the northern Karbi Hills, NE India for porphyry copper mineralization

Majumdar, Dilip; Gogoi, Abhijit

doi:10.1016/j.oregeorev.2020.103467

Cited by 3 publications

(10 citation statements)

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“…The existence of calc‐alkaline host granitoids, absence of xenoliths, oxidized condition of magma, higher temperature of magma formation and high K and silica content all are indicators of porphyry fertility. All of these properties are found in Kuthori‐Bagori granitoids (Majumdar & Gogoi, 2020). As per the mechanism of ore concentration in magma, calc‐alkaline magma composition with a metaluminous character favours the creation of more octahedral coordination sites in the melt phase during magmatic crystallization and differentiation, enabling copper to remain in the melt phase till achieving the second boiling stage.…”

Section: Discussionmentioning

confidence: 96%

“…Granitoids and constituent sulphides both have a mantle signature, with a wholerock ( 87 Sr/ 86 Sr) ratio of 0.703 for granitoids and δ 34 S ( 34 S/ 32 S) is +4.5 ± 0.05‰ for constituent sulphides (Majumdar & Dutta, 2007). However, subsequent tectono‐magmatic activities were marked by an extensional episode that began ~1,644 ± 33 Ma (Gogoi et al, 2019), during which the previously formed granulitic crust partially melted, resulting in the production of A‐type granitoids in the Kuthori‐Bagori and other parts of the Karbi Hills (Majumdar & Gogoi, 2020). Granitoids of the granite‐granodiorite‐quartz monzonite clan showed a positive Hf ( t ) (+3.2 to +9.7) of constituent zircon (Gogoi et al, 2019; Majumdar & Dutta, 2007; Majumdar & Gogoi, 2020).…”

Section: Geology and Mineralization Featuresmentioning

confidence: 99%

“…However, subsequent tectono‐magmatic activities were marked by an extensional episode that began ~1,644 ± 33 Ma (Gogoi et al, 2019), during which the previously formed granulitic crust partially melted, resulting in the production of A‐type granitoids in the Kuthori‐Bagori and other parts of the Karbi Hills (Majumdar & Gogoi, 2020). Granitoids of the granite‐granodiorite‐quartz monzonite clan showed a positive Hf ( t ) (+3.2 to +9.7) of constituent zircon (Gogoi et al, 2019; Majumdar & Dutta, 2007; Majumdar & Gogoi, 2020). The Kuthori‐Bagori granitoids are grey‐coloured, fine‐grained and show hypidiomorphic, inequigranular granitic textures (Figure 2a–f).…”

Section: Geology and Mineralization Featuresmentioning

confidence: 99%

“…The Karbi Hills does not have any proven metalliferous deposit (Majumdar & Dutta, 2007, 2014; Majumdar & Gogoi, 2020; Saha et al, 2010). Prospecting for base metal sulphide in the Precambrian shield of the Karbi Hills has thus remained a difficult task.…”

Section: Introductionmentioning

confidence: 99%

“…(a) Geological map of the study area (modified after Majumdar & Gogoi, 2020). (b) Cross‐sectional view of Kuthori‐Bagori mineralized zone…”

Section: Introductionmentioning

confidence: 99%

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Geochemistry and magnetite mineral properties in a porphyry copper prospect in A‐type granitoids: A case study from the Karbi Hills of Northeast India

et al. 2022

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This paper discusses the porphyry copper mineralization in A‐type granitoids from the Precambrian shield of the Karbi Hills (Mikir Hills), NE India. The prospective zone lies in the Kuthori‐Bagori of Kaziranga locality of the north Karbi Hills. The host granitoids are characterized by intermediate to high SiO2 (66.30–72.97 wt.%), Na2O (up to 4.90 wt.%), Ba (up to 1,943 ppm), Zr (up to 410 ppm), Y (up to 70 ppm) and Al2O3 (up to 14.77 wt.%) with low concentrations of CaO (up to 1.53 wt.%), and Cu (up to 32.41 ppm) which suggest a consistent granodiorite‐monzogranite host composition, an intraplate emplacement, A‐type chemistry, shoshonitic to high‐K calc‐alkaline and a predominant metaluminous character. Minerals in the investigated granitoids show hypogene alteration features similar to ideal porphyry style mineralization. Remnants of early chalcopyrite‐bornite‐magnetite (Magnetite‐I) veins have been preserved in the distant propylitic zone. The central core zone of potassic alteration shows the dominance of pyrite‐chalcopyrite‐magnetite (Magnetite‐II) assemblages. Mineral chemistry confirms the presence of two types of magnetites: magmatic (Mag‐I) and hydrothermal (Mag‐II). Mag‐I is octahedral, less commonly cubic, or irregular. It has a porous core with trellis‐type ilmenite exsolution lamellae. Mag‐II is non‐porous, devoid of ilmenite exsolution lamellae, has irregular to distinctly octahedral crystal habit and contains micro‐inclusions of pyrite, chalcopyrite, aluminosilicates, manganite and apatite. The progressive chemical purification of igneous magnetite, exacerbated by hydrothermal re‐equilibration, has resulted in a significant reduction in trace element contents such as Ti, Al, Mg, Zn and Cr, and a significant increase in iron content from 89 to ~94 wt.%. A combination of [Ni/(Cr + Mn) vs. Ti + V], and [(Ca + Al + Mn) vs. Ti + V] variation diagrams and upper threshold concentrations for the Kuthori‐Bagori ore effectively separates Mag‐I and Mag‐II. Our field, petrographic and geochemical data indicate that the Kuthori‐Bagori of Kaziranga granitoid of the Karbi Hills (Mikir Hills) in NE India is an ideal location for porphyry copper mineralization.

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Section: Discussionmentioning

confidence: 96%

Section: Geology and Mineralization Featuresmentioning

confidence: 99%

Section: Geology and Mineralization Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…(a) Geological map of the study area (modified after Majumdar & Gogoi, 2020). (b) Cross‐sectional view of Kuthori‐Bagori mineralized zone…”

Section: Introductionmentioning

confidence: 99%

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Geochemistry and magnetite mineral properties in a porphyry copper prospect in A‐type granitoids: A case study from the Karbi Hills of Northeast India

et al. 2022

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Porphyry indicator zircons (PIZ) from the Kaziranga porphyry Cu–S mineralization, NE India: an exploratory tool assessing magma fertility

Majumdar,

Gogoi,

Cottle

et al. 2024

Int J Earth Sci (Geol Rundsch)

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Geochemical constraints on the petrogenesis of mafic rocks (metadolerites) from the Proterozoic Shillong Basin, Northeast India: implications for growth of the Greater Indian Landmass

et al. 2023

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The Paleo-Mesoproterozoic Shillong Basin of the Assam-Meghalaya Gneissic Complex is exposed in parts of Northeast India. The studied metadolerites are from the volcano-sedimentary sequence of Shillong Basin from the Borjuri area in the Mikir Massif. This episode of mafic magmatism can be correlated with the Columbia supercontinent formation and bears significance to its reconstruction. The present work discusses the field, petrography and geochemical characteristics of the metadolerites, which occur in close association with the quartzites of the Shillong Group of rocks (metasedimentary rocks of the Shillong Basin). Our data show distinctive characteristics of subduction-related magmatism exhibiting high LREE/HREE, large ion lithophile element/high field strength element ratios and pronounced negative Nb anomaly. Elemental ratios such as Zr/Ba (0.21–0.46), La/Nb (1.23–2.32) and Ba/Nb (30.08–56.90) point to a fluid-enriched lithospheric mantle source in a subduction regime. Metadolerites plot in the field of ‘back-arc basin basalts’ in tectonic discrimination diagrams reinforcing a subduction zone tectonic setting. The mafic rocks correspond to a 6–10 % partial melting of a mantle source incorporating spinel+garnet lherzolite. The metamorphic P-T of the metadolerites estimated from plagioclase-hornblende geothermobarometer (7–8 kbar, 664 °C) is indicative of amphibolite facies metamorphism in a medium P-T zone. Based on the comparative analysis of field observation, petrography, geochemistry and geological ages given by previous workers, we infer that the Shillong Basin represents a back-arc rift region and is the eastern continuation of the Bathani volcano-sedimentary sequence of the Chotanagpur Granite Gneiss Complex marking continuation of the Central Indian Tectonic Zone to the Mikir Massif.

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Prospectivity of Mesoproterozoic magmatism in the northern Karbi Hills, NE India for porphyry copper mineralization

Cited by 3 publications

References 46 publications

Geochemistry and magnetite mineral properties in a porphyry copper prospect in A‐type granitoids: A case study from the Karbi Hills of Northeast India

Geochemistry and magnetite mineral properties in a porphyry copper prospect in A‐type granitoids: A case study from the Karbi Hills of Northeast India

Porphyry indicator zircons (PIZ) from the Kaziranga porphyry Cu–S mineralization, NE India: an exploratory tool assessing magma fertility

Geochemical constraints on the petrogenesis of mafic rocks (metadolerites) from the Proterozoic Shillong Basin, Northeast India: implications for growth of the Greater Indian Landmass

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