PGE geochemistry of the Eagle Ni–Cu–(PGE) deposit, Upper Michigan: constraints on ore genesis in a dynamic magma conduit

Ding, Xun‐Lei; Ripley, Edward M.; Li, Chusi

doi:10.1007/s00126-011-0350-y

Cited by 53 publications

(10 citation statements)

References 28 publications

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“…; Ding et al. ). While the above suggests that pentlandite exsolves from pyrrhotite, Hawley () suggested that some natural pyrrhotite grains could form via exsolution from the slow cooling of a sulfur‐rich pentlandite.…”

Section: Discussionmentioning

confidence: 98%

Heterogeneous histories of Ni‐bearing pyrrhotite and pentlandite grains in the CI chondrites Orgueil and Alais

Berger

Лауретта

Zega

et al. 2016

Meteorit & Planetary Scien

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Compositional and structural analyses of CI chondrite iron–nickel sulfide grains reveal heterogeneity both across and within the Orgueil and Alais meteorites. Orgueil grains with the 4C monoclinic pyrrhotite structure have variable metal‐to‐sulfur ratios and nickel contents. These range from the nominal ratio of 0.875 for Fe7S8 with <1 atom% nickel to a high metal‐to‐sulfur ratio of 0.97 with 15 atom% nickel. These data reveal a previously unrecognized low‐temperature solid solution between Fe7S8 and Fe5Ni3S8. We have also identified 6C monoclinic pyrrhotite among the Orgueil iron–nickel sulfides. The occurrence of pentlandite in Orgueil is confirmed for the first time crystallographically. In contrast, sulfide grains in Alais do not show the same spread in composition and structure; rather they represent the endmembers: low‐Ni 4C monoclinic pyrrhotite and pentlandite. We investigate possible formation/alteration scenarios: crystallization from a melt, solid‐state diffusion and/or exsolution, oxidation of pre‐existing sulfides, and precipitation from a fluid. Sulfide grains are sensitive to alteration conditions; these data suggest that the structures and compositions of the sulfide assemblages in Orgueil and Alais were established by late‐stage parent body aqueous alteration, followed in some cases by low‐temperature solid‐state processes. The samples record different alteration histories, with Orgueil experiencing lower equilibration temperatures (25 °C) than Alais (100–135 °C). We conclude that millimeter‐scale heterogeneity existed in alteration conditions (e.g., temperature, pH, oxygen fugacity, sulfur fugacity, duration of alteration) on the parent body. This variability is evidenced by the diversity among sulfide grains located within millimeters of one another.

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Section: Discussionmentioning

confidence: 98%

Heterogeneous histories of Ni‐bearing pyrrhotite and pentlandite grains in the CI chondrites Orgueil and Alais

Berger

Лауретта

Zega

et al. 2016

Meteorit & Planetary Scien

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“…Quantifying the proportion of crustal contamination is highly dependent on concentrations chosen for the country rock contaminant (e.g., Thomson Formation), as well as the mechanism of element liberation (selective enrichment via devolatilization, partial melting, etc. ; see Ripley and Li (2011);Ding et al (2012)). Using an average composition of the Thomson Formation as an end-member with 9.77 ppm Th, the data suggest that in some portions of the TIC between 20 and 55% of the Th could be derived from the Thomson formation.…”

Section: Trace Element Characteristicsmentioning

confidence: 94%

Petrogenesis of the Ni–Cu–PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota

Taranovic

Ripley

et al. 2015

Lithos

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“…The Eagle deposit is one of the smallest magmatic sulfide deposits in the world. It contains ~4 Mt of sulfide ores with average grades of 3.6 wt % Ni and 2.9 wt % Cu (Ding et al, 2012). These data indicate that the Erbutu deposit is smaller than the Eagle deposit.…”

Section: Geology and Petrographymentioning

confidence: 81%

The Erbutu Ni-Cu Deposit in the Central Asian Orogenic Belt: A Permian Magmatic Sulfide Deposit Related to Boninitic Magmatism in An Arc Setting

Peng

Yusheng

et al. 2013

Economic Geology

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The Erbutu Ni-Cu sulfide deposit is hosted in a small ultramafic intrusion located at the southern margin of the Central Asian orogenic belt, Inner Mongolia. This deposit is the first case of a magmatic sulfide deposit related to boninitic magmatism in an arc setting. The host intrusion is composed of orthopyroxenite and olivine orthopyroxenite. More than three quarters of the intrusion contains economic, disseminated sulfide mineralization. SHRIMP U-Pb dating of zircons from the intrusion gives a crystallization age of 294.2 ± 2.7 Ma, similar to the age of the Permian Tarim plume in northwest China. Olivine orthopyroxenite is characterized by olivine crystals with relatively high Fo contents (85−88 mol %) and extremely low Ca contents (<250 ppm). Coexisting orthopyroxene crystals have clinoenstatite composition with enstatite from 86 to 88 mol %. Whole-rock data show characteristic enrichments of light REE relative to heavy REE, pronounced negative Nb-Ta anomalies, and moderately positive Hf anomaly. The d 34 S values of sulfide separates are 4 to 5‰, significantly higher than the typical mantle value (0 ± 2‰). The eHf values of zircons are from -4 to -9. These data indicate that the parental magma was a boninite. Crustal contamination was involved during magma evolution and ore formation.

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PGE geochemistry of the Eagle Ni–Cu–(PGE) deposit, Upper Michigan: constraints on ore genesis in a dynamic magma conduit

Cited by 53 publications

References 28 publications

Heterogeneous histories of Ni‐bearing pyrrhotite and pentlandite grains in the CI chondrites Orgueil and Alais

Heterogeneous histories of Ni‐bearing pyrrhotite and pentlandite grains in the CI chondrites Orgueil and Alais

Petrogenesis of the Ni–Cu–PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota

The Erbutu Ni-Cu Deposit in the Central Asian Orogenic Belt: A Permian Magmatic Sulfide Deposit Related to Boninitic Magmatism in An Arc Setting

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