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Anatomical similarities and differences between spatially associated porphyry copper-gold deposits at the Reko Diq H14 and H15 complex, Balochistan, Pakistan

Abdul Razique, Richard Tosdal and Farhad Bouzari
Anatomical similarities and differences between spatially associated porphyry copper-gold deposits at the Reko Diq H14 and H15 complex, Balochistan, Pakistan (in Tectonics and metallogeny of the Tethyan orogenic belt, Jeremy P. Richards (editor))
Special Publication (Society of Economic Geologists (U. S.)) (2016) 19: 259-278

Abstract

The Reko Diq porphyry cluster in the western Chagai magmatic belt, Pakistan, contains a geologic resource of 5.9 billion tons (5.35 Bt)0.41% Cu and 0.22 g/t Au, largely in the H14 and H15 porphyry deposits. These two deposits, located approximately 1 km apart, are related to a series of petrologically similar, middle Miocene (12.6-12.0 Ma), calc-alkaline porphyry intrusions hosted by Oligocene andesitic volcanic and clastic sedimentary rocks. The porphyry intrusions are characterized by phenocrysts of plagioclase, biotite, quartz, and amphibole in a microcrystalline mafic silicate-bearing quartzofeldspathic groundmass. Potassic, sericitechlorite, sericitic, and propylitic alteration assemblages are zoned about the porphyry intrusions. The early and intermineral porphyry intrusions are overprinted by a pervasive potassic alteration assemblage composed of hydrothermal biotite-K-feldspar-magnetite + or - anhydrite with associated chalcopyrite and bornite. Chalcopyrite, bornite, and lesser pyrite are disseminated or are associated with a stockwork of quartz + or - magnetite + or - K-feldspar A- and B-type and less common sulfide-only veins. Bornite characterizes a distinct high-grade core to the H14 deposit, but it is less common and always subsidiary in volume to chalcopyrite in the slightly older H15 deposit. Local sulfide mineral assemblages of pyrite-covellite-bornite-chalcopyrite associated with pervasive quartz-sericite alteration assemblages in the H15 deposit form narrow, steeply dipping vein-like zones or strata-bound horizons restricted to felsic tuff or sandstone. The late porphyry intrusions are weakly altered and mineralized, lack volumetrically significant veins, and generally have low Cu and Au concentrations. Sulfide-deficient potassic alteration assemblages at greater than 1,000 m depth are overprinted by a texturally destructive alteration assemblage of albite-epidote + or - actinolite + or - chlorite, inferred to represent a sodic-calcic alteration assemblage. Total sulfide contents at these depths are less than 1%. At shallow depths, a sericitechlorite alteration assemblage overprints potassic alteration mainly along late-stage centimeter-scale chalcopyrite-pyrite D-type veins. The sericite-chlorite assemblage is much more extensive in the H15 deposit than in the H14 deposit. An outer sericitic alteration assemblage composed of quartz-muscovite-pyrite + or - chalcopyrite flanks the sericite-chlorite assemblage. An intermediate argillic alteration assemblage composed of clay minerals (illite, smectite, montmorillonite) and carbonate is common in remnants of plagioclase within the sericitechlorite and sericitic alteration assemblages. A propylitic alteration assemblage of chlorite-epidote-albite + or - pyrite-carbonate is developed in the peripheral volcanic and sedimentary host rocks surrounding the H14-H15 porphyry complex.


ISSN: 1547-3112
Serial Title: Special Publication (Society of Economic Geologists (U. S.))
Serial Volume: 19
Title: Anatomical similarities and differences between spatially associated porphyry copper-gold deposits at the Reko Diq H14 and H15 complex, Balochistan, Pakistan
Title: Tectonics and metallogeny of the Tethyan orogenic belt
Author(s): Razique, AbdulTosdal, RichardBouzari, Farhad
Author(s): Richards, Jeremy P.editor
Affiliation: University of British Columbia, Mineral Deposit Research Unit, Vancouver, BC, Canada
Affiliation: University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada
Pages: 259-278
Published: 2016
Text Language: English
Publisher: Society of Economic Geologists, Littleton, CO, United States
References: 46
Accession Number: 2018-013081
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, geol. sketch maps
N28°28'43" - N28°28'43", E65°38'37" - E65°38'37"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 201807
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