Re-Os isotopic evidence for an enriched-mantle source for the Noril'sk-type, ore-bearing intrusions, Siberia

Walker, Richard J.; Morgan, John; Horan, M. F.; Czamanske, Gerald K.; Krogstad, E. J.; Fedorenko, V. A.; Kunilov, Vladimir E.

doi:10.1016/0016-7037(94)90272-0

Cited by 200 publications

(82 citation statements)

References 48 publications

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“…Chalcophile elements have been widely used to study the origin of magmatic sulfide deposits because they have very high partition coefficients between sulfide liquid and magma (Bezmen et al, 1994;Fleet et al, 1999) and are therefore good indicators for sulfide segregation. Re-Os isotopes are useful in detecting crustal contamination of mantle-derived magma during ore formation (e.g., Walker et al, 1994;Sproule et al, 1999;Lambert et al, 2000;Lesher and Burnham, 2001). A combination of lithophile-chalcophile trace elements and Sr-Nd-Os isotopes is widely used in assessing the role of fractional crystallization and crustal contamination in the formation of magmatic sulfide deposits.…”

Section: Introductionmentioning

confidence: 99%

Origin of PGE-Depleted Ni-Cu Sulfide Mineralization in the Triassic Hongqiling No. 7 Orthopyroxenite Intrusion, Central Asian Orogenic Belt, Northeastern China

Wei¹,

Wang²,

Li³

et al. 2013

Economic Geology

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The ~216 Ma Hongqiling No. 7 intrusion is located in the southern margin of the Central Asian orogenic belt, northeastern China. It was the second largest Ni producer after Jinchuan in China. The intrusion crops out in an area of ~0.013 km 2 on the surface. It intruded gneisses and marbles of the Paleozoic Hulan Formation. The intrusion is mainly composed of orthopyroxenite (~95 vol %), with minor harzburgite and norite. Over 90 vol % of the intrusion contains disseminated, net-textured or massive sulfides. The bulk sulfide ores (recalculated to 100% sulfide) have low average PGE concentrations (5.6 ppb Os, 3.1 ppb Ir, 4.7 ppb Ru, 2.2 ppb Rh, 31 ppb Pt, and 11 ppb Pd) and high Cu/Pd ratios (3 × 10 5 −3 × 10 7 ), consistent with the compositions of sulfide liquids segregated from PGE-depleted magma. Olivine composition (Fo <86 mol %) indicates a fractionated parental magma. Back calculation shows that the parental magma was possibly derived by olivine fractionation from a primary magma containing ~16 wt % MgO. Numerical modeling indicates that PGE depletion in the parental magma of the Hongqiling No. 7 intrusion was due to previous sulfide segregation in the staging chamber. Whole-rock data show light rare earth element (REE) enrichments, negative Nb-Ta anomalies, and positive eNd (t = 216 Ma) values from 3 to 5, which can be explained by mixing of a mantle-derived magma with a granitic melt formed by magma underplating in the crust. The gOs (t = 216 Ma) values of sulfide ores vary from 50 to 187. The highly variable gOs(t) values coupled with similar eNd(t) values indicate preferential assimilation of crustal sulfides during magma rock interaction. Based on the observations, we propose that the parental magma of the Hongqiling No. 7 intrusion formed by contamination of mantle-derived, S-undersaturated magma by crustally derived granitic melt, together with olivine crystallization, in a staging chamber. The contaminated magma became PGE depleted due to sulfide segregation in response to crustal contamination. The PGE-depleted magma became S undersaturated again during ascent due to the negative effect of pressure on the maximum solubility of sulfur in magma. Upon arrival near the present level of the Hongqiling No. 7 intrusion a second event of sulfide segregation took place due to addition of crustal sulfides from immediate country rocks. The immiscible sulfide liquids and orthopyroxene crystallizing from the magma were retained in a dynamic conduit to form the ore-bearing intrusion while much of the magma left the conduit to form some of the nearby sulfidepoor intrusions. We suggest future exploration in the region to focus on olivine-bearing and orthopyroxenedominant intrusions with ages similar to that of the Hongqiling No. 7 intrusion.

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Section: Introductionmentioning

confidence: 99%

Origin of PGE-Depleted Ni-Cu Sulfide Mineralization in the Triassic Hongqiling No. 7 Orthopyroxenite Intrusion, Central Asian Orogenic Belt, Northeastern China

Wei¹,

Wang²,

Li³

et al. 2013

Economic Geology

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“…In contrast, the 187 Os/ 188 Os of the PGE sulfide ores from the Bushveld Complex, South Africa, are between 0.15 and 0.20 (29). The 187 Os/ 188 Os of base-metal sulfide deposits are variable; in some cases they are similar to the PGE ores [e.g., Noril'sk, Russia (30), and Yilgarn craton, Australia (31)], and in other cases they are highly radiogenic because of involvement of continental crust in their formation [e.g., Sudbury, Canada (32)]. Chromites of all ages have uniformly low 187 Os/ 188 Os values, ranging from 0.12 to 0.14 (33).…”

mentioning

confidence: 99%

Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

Chen

Sedwick

Sharma

2009

Proc. Natl. Acad. Sci. U.S.A.

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Osmium is one of the rarer elements in seawater, with typical concentration of Ϸ10 ؋ 10 ؊15 g g ؊1 (5.3 ؋ 10 ؊14 mol kg ؊1 ). The osmium isotope composition ( 187 Os/ 188 Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (Ϸ1.3) and mantle/cosmic dust (Ϸ0.13). Here, we show that the 187 Os/ 188 Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (Ϸ0.2) that are processed to extract platinum and other metals to be used primarily in automobile catalytic converters. Present-day surface seawater has a lower 187 Os/ 188 Os ratio (Ϸ0.95) than deep waters, suggesting that human activities have altered the isotope composition of the world's oceans and impacted the global geochemical cycle of osmium. The contamination of the surface ocean is particularly remarkable given that osmium has few industrial uses. The pollution may increase with growing demand for platinum-based catalysts.pollution ͉ seawater ͉ isotopes ͉ platinum group metals ͉ precipitation

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“…The γOs(t) value is thus an important parameter because it is capable of indicating the involvement of crustal material in the metallogenic system (Walker et al 1994 On a common Os vs. Re/Os diagram (Fig. 8), the Hulu sulfide ores plot in the fields between Duluth sulfides and S-rich sediments, also suggesting that sulfide-bearing sediments might have been added during formation of the sulfide ores.…”

Section: Evidence For Crustal Contaminationmentioning

confidence: 99%

SIMS U-Pb zircon dating and Re-Os isotopic analysis of the Hulu Cu-Ni deposit, eastern Tianshan, Central Asian Orogenic Belt, and its geological significance

Han¹,

Xiao

Zhao³

et al. 2013

J. Geosci.

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Exploration of the Hulu Cu-Ni-Co sulfide deposit in Eastern Tianshan, Central Asian Orogenic Belt, has detected horizons of sulfide mineralization in pyroxenite and peridotite units. SIMS U-Pb zircon ages of the gabbro-hosting Cu-Ni-Co sulfide deposit indicate that the Hulu intrusion was emplaced at 282.3 ± 1.2 Ma (95% confidence level, MSWD = 3.30, n = 13). Osmium isotopic data suggest that the Hulu intrusion and associated Cu-Ni mineralization were derived from crustally-contaminated mantle melts. The intrusions clearly show island-arc geochemical signatures, such as negative Nb, Ta, Zr and Ti anomalies and enrichment in LILE. These geochemical tracers indicate that the Hulu mafic-ultramafic intrusions, along with the Cu-Ni deposit, formed as a result of subduction of oceanic crust in the Early Permian. The arc-related geodynamic setting of the Hulu Cu-Ni deposit is unusual for magmatic sulfide deposits. This new type of ore deposit offers an alternative perspective for Cu and Ni exploration.

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Re-Os isotopic evidence for an enriched-mantle source for the Noril'sk-type, ore-bearing intrusions, Siberia

Cited by 200 publications

References 48 publications

Origin of PGE-Depleted Ni-Cu Sulfide Mineralization in the Triassic Hongqiling No. 7 Orthopyroxenite Intrusion, Central Asian Orogenic Belt, Northeastern China

Origin of PGE-Depleted Ni-Cu Sulfide Mineralization in the Triassic Hongqiling No. 7 Orthopyroxenite Intrusion, Central Asian Orogenic Belt, Northeastern China

Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

SIMS U-Pb zircon dating and Re-Os isotopic analysis of the Hulu Cu-Ni deposit, eastern Tianshan, Central Asian Orogenic Belt, and its geological significance

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