MINERAL CHEMISTRY AND SHRIMP U-Pb GEOCHRONOLOGY OF MESOPROTEROZOIC POLYCRASE-TITANITE VEINS IN THE SULLIVAN Pb-Zn-Ag DEPOSIT, BRITISH COLUMBIA

Slack, John F.; Aleinikoff, John N.; Belkin, Harvey E.; Ransom, P W

doi:10.3749/canmin.46.2.361

Cited by 9 publications

(2 citation statements)

References 36 publications

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“…1220 Ma, i.e., broadly Grenvillian(Arkadakskiy et al, 2009). Other evidence of hydrothermal mineral precipitation (or recrystallization) of Grenvillian age in the Belt-Purcell Basin was reported bySlack et al (2008) for polycrase and titanite in the Sullivan Pb-Zn-Ag deposit at ca. 1150-1050 Ma, and byAleinikoff et al (2015) for xenotime at ca.…”

mentioning

confidence: 70%

Re-Os systematics and geochemistry of cobaltite (CoAsS) in the Idaho cobalt belt, Belt-Purcell Basin, USA: Evidence for middle Mesoproterozoic sediment-hosted Co-Cu sulfide mineralization with Grenvillian and Cretaceous remobilization

Saintilan

Creaser

Bookstrom

2017

Ore Geology Reviews

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We report the first study of the Re-Os systematics of cobaltite (CoAsS) using disseminated grains and massive sulfides from samples of two breccia-type and two stratabound deposits in the Co-Cu-Au Idaho cobalt belt (ICB), Lehmi Sub-basin to the Belt-Purcell Basin, Idaho, USA. Using a 185 Re+ 190 Os spike solution, magnetic and non-magnetic fractions of cobaltite mineral separates give reproducible Re-Os analytical data for aliquot sizes of 150 to 200 mg. Cobaltite from the ICB has highly radiogenic 187 Os/ 188 Os ratios (17-45) and high 187 Re/ 188 Os ratios (600-1800) but low Re and total Os contents (ca. 0.4-4 ppb and 14-64 ppt, respectively). Containing 30 to 74% radiogenic 187 Os, cobaltite from the ICB is amenable to Re-Os age determination using the isochron regression approach.Re-Os data for disseminated cobaltite mineralization in a quartz-tourmaline breccia from the Haynes-Stellite deposit yield a Model 1 isochron age of 1349 ± 76 Ma (2σ, n = 4, mean squared weighted deviation MSWD = 2.1, initial 187 Os/ 188 Os ratio = 4.7 ± 2.2). This middle Mesoproterozoic age is preserved despite a possible metamorphic overprint or a pulse of metamorphic-hydrothermal remobilization of pre-existing cobaltite that formed along fold cleavages during the ca. 1190-1006 Ma Grenvillian orogeny. This phase of remobilization is tentatively identified by a Model 3 isochron age of 1132 ± 240 Ma (2σ, n = 7, MSWD = 9.3, initial 187 Os/ 188 Os ratio of 9.0 ± 2.9) for cobaltite in the quartztourmaline breccia from the Idaho zone.All Mesoproterozoic cobaltite mineralization in the district was affected by greenschist-to lower amphibolites-facies (garnet zone) metamorphism during the Late Jurassic to Late Cretaceous Cordilleran orogeny. However, the fine-to coarse-grained massive cobaltite mineralization from the shear zonehosted Chicago zone is the only studied deposit that has severely disturbed Re-Os systematics with evidence for a linear trend of mixing with (metamorphic?) fluids.The new Re-Os ages and extremely high initial 187 Os/ 188 Os ratios of cobaltite reported here favor a magmatic-hydrothermal genetic model for a multi-stage REE-Y-Co-Cu-Au mineralization occurring at ca. 1370 to 1349 Ma, and related to the emplacement of the Big Deer Creek granite pluton at ca. 1377 Ma. In our model, deposition of paragenetically early xenotime and gadolinite was followed by an influx of Mesoproterozoic evaporitic brines and magmatic-hydrothermal fluids containing metals and reduced sulfur derived from mafic and oceanic island-arc Archean to Paleoproterozoic rocks in the Laurentian basement. Cobaltite mineralization (and the closure of the Re-Os isotopic system in this mineral) occurred upon cooling of these fluids at an inferred temperature of 300ºC or below.

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mentioning

confidence: 70%

Re-Os systematics and geochemistry of cobaltite (CoAsS) in the Idaho cobalt belt, Belt-Purcell Basin, USA: Evidence for middle Mesoproterozoic sediment-hosted Co-Cu sulfide mineralization with Grenvillian and Cretaceous remobilization

Saintilan

Creaser

Bookstrom

2017

Ore Geology Reviews

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“…This Grenvillian event, which has been recently confirmed to have impacted geological units located in northwestern present-day North America, was responsible for widespread hydrothermal activity causing mineral precipitation (or recrystallization) in the Belt-Purcell Basin between ca. 1,160 and 1,040 Ma [21,39,59,63].…”

Section: Evaluation Of Re-os Dates and Timing Of Pyrite Andmentioning

confidence: 99%

Synsedimentary to Diagenetic Cu±Co Mineralization in Mesoproterozoic Pyritic Shale Driven by Magmatic-Hydrothermal Activity on the Edge of the Great Falls Tectonic Zone–Black Butte, Helena Embayment, Belt-Purcell Basin, USA: Evidence from Sulfide Re-Os Isotope Geochemistry

et al. 2021

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The ca. 1,500 to 1,325 Ma Mesoproterozoic Belt-Purcell Basin is an exceptionally preserved archive of Mesoproterozoic Earth and its paleoenvironmental conditions. The Belt-Purcell Basin is also host to world-class base metal sediment-hosted mineralization produced in a variety of settings from the rift stage of basin evolution through the subsequent influence of East Kootenay and Grenvillian orogenies. The mineral potential of this basin has not been fully realized yet. New rhenium-osmium (Re-Os) data presented here for chalcopyrite, pyrite, and black shale contribute to refine a robust genetic model for the origin of the Black Butte copper±cobalt±silver (Cu±Co±Ag) deposit hosted by the ca. >1,475 Ma Newland Formation in the Helena Embayment of the Belt-Purcell Basin in Montana, USA. Chalcopyrite Re-Os data yield an isochron age (1,488±34 Ma, unradiogenic initial 187Os/188Os composition Osi-chalcopyrite=0.13±0.11) that overlaps with the geological age of the Newland Formation. Further, the Re-Os data of synsedimentary to diagenetic massive pyrite yield evidence of resetting with an isochron age (1,358±42 Ma) coincident with the timing of the East Kootenay orogeny. The unradiogenic Osi-chalcopyrite at ca. 1,488 Ma (0.13±0.11) argues for derivation of Os from a magmatic source with a 187Os/188Os isotopic composition inherited from the upper mantle in the Mesoproterozoic (Osmantle 1,475 Ma=0.12±0.02). The unradiogenic Osi-chalcopyrite also suggests limited contamination from a continental crustal source. This source of Os and our new sulfur isotopic signatures of chalcopyrite (–4.1 to +2.1‰-VCDT) implies a dominantly magmatic source for metals. We integrate our new results and previously published geological and geochemical evidence to conceptualize a genetic model in which Cu and metals were largely contributed by moderate-temperature, reduced magmatic-hydrothermal fluids carrying reduced sulfur species with a magmatic origin and flowing as highly metalliferous fluids within the shale sequence. A subsidiary derivation of metals during thermally forced shale diagenesis is possible. Chalcopyrite mineralization replaced locally massive synsedimentary to diagenetic pyrite units close to the sediment-water interface, i.e., an ideal locus where magmatic-hydrothermal fluids could cool and the solubility of chalcopyrite would fall. We suggest that Cu mineralization was coeval with the timing of an enhanced thermal gradient in the Helena Embayment triggered until ca. 1,455 Ma by tholeiitic dike swarm that intruded into Archean basement rocks and intersected the NE-SW-trending Great Falls Tectonic Zone.

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Hydrothermal titanite from the Chengchao iron skarn deposit: temporal constraints on iron mineralization, and its potential as a reference material for titanite U–Pb dating

McFarlane

2017

Miner Petrol

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MINERAL CHEMISTRY AND SHRIMP U-Pb GEOCHRONOLOGY OF MESOPROTEROZOIC POLYCRASE-TITANITE VEINS IN THE SULLIVAN Pb-Zn-Ag DEPOSIT, BRITISH COLUMBIA

Cited by 9 publications

References 36 publications

Re-Os systematics and geochemistry of cobaltite (CoAsS) in the Idaho cobalt belt, Belt-Purcell Basin, USA: Evidence for middle Mesoproterozoic sediment-hosted Co-Cu sulfide mineralization with Grenvillian and Cretaceous remobilization

Re-Os systematics and geochemistry of cobaltite (CoAsS) in the Idaho cobalt belt, Belt-Purcell Basin, USA: Evidence for middle Mesoproterozoic sediment-hosted Co-Cu sulfide mineralization with Grenvillian and Cretaceous remobilization

Synsedimentary to Diagenetic Cu±Co Mineralization in Mesoproterozoic Pyritic Shale Driven by Magmatic-Hydrothermal Activity on the Edge of the Great Falls Tectonic Zone–Black Butte, Helena Embayment, Belt-Purcell Basin, USA: Evidence from Sulfide Re-Os Isotope Geochemistry

Hydrothermal titanite from the Chengchao iron skarn deposit: temporal constraints on iron mineralization, and its potential as a reference material for titanite U–Pb dating

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