Heterogeneous Os isotope compositions in the Kalatongke sulfide deposit, NW China: the role of crustal contaminationReport as inadecuate




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Mineralium Deposita

, Volume 47, Issue 7, pp 731–738

First Online: 12 April 2012Received: 22 November 2010Accepted: 25 January 2012

Abstract

Re–Os isotope compositions of mantle-derived magmas are highly sensitive to crustal contamination because the crust and mantle have very different Os isotope compositions. Crustal contamination may trigger S saturation and thus the formation of magmatic Ni–Cu–PGE sulfide deposits. The ∼287-Ma Kalatongke norite intrusion of NW China are hosted in carboniferous tuffaceous rocks and contain both disseminated and massive sulfide mineralization. The Re–Os isotope compositions in the intrusion are highly variable. Norite and massive sulfide ores have γOs values ranging from +59 to +160 and a Re–Os isochron age of 239 ± 51 Ma, whereas disseminated sulfide ores have γOs values from +117 to +198 and a Re–Os isochron age of 349 ± 34 Ma. The variability of Os isotope compositions can be explained as the emplacement of two distinct magma pulses. Massive sulfide ores and barren norite in the intrusion formed from the same magma pulse, whereas the disseminated sulfide ores with more radiogenic Os isotopes formed from another magma pulse which underwent different degrees of crustal contamination. Re–Os isotopes may not be suitable for dating sulfide-bearing intrusions that underwent variable degrees of crustal contamination to form magmatic sulfide deposits.

KeywordsRe–Os isotopes Sulfides Sulfide-bearing intrusions Crustal contamination Sulfide segregation Editorial handling: F. Barra

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Author: Jian-Feng Gao - Mei-Fu Zhou - Peter C. Lightfoot - Wenjun Qu

Source: https://link.springer.com/







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