کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8911838 | 1638625 | 2017 | 27 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Graphite-(Mo,W)S2 intergrowth as a palaeoenvironmental proxy in metasedimentary rocks
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
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چکیده انگلیسی
Molybdenum enrichment in pristine organic-C-rich sedimentary rocks forms the basis for inferring the presence of dissolved oxygen in seawater. Organic matter removes dissolved hexavalent Mo from seawater where anoxic and euxinic conditions are attained. However, it is unknown whether this Mo-based proxy is retained under metamorphic conditions where organic C is no longer preserved. Here, we describe aggregates of graphite and molybdenite (MoS2) containing up to 21 mass per cent of W as tungstenite (WS2) in solid solution. These aggregates are disseminated in a sulfide-rich Mn-silicate-carbonate rock (queluzite), metamorphosed under amphibolite-facies conditions within the Archaean Barbacena greenstone belt in Minas Gerais, Brazil. Our finding indicates that: (i) W is, like Mo, a palaeoenvironmental proxy; (ii) the W proxy is sensitive to high fS2/fO2 environments; (iii) both Mo and W proxies survive amphibolite-facies overprint as (Mo,W)S2 intergrown with graphite. Archaean greenstones are potential candidates for storing palaeoenvironmental information as (Mo,W)S2-graphite intergrowths.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 294â295, December 2017, Pages 412-417
Journal: Lithos - Volumes 294â295, December 2017, Pages 412-417
نویسندگان
Alexandre Raphael Cabral, Armin Zeh, NÃvea Cristina da Silva Viana, Thomas Schirmer, Bernd Lehmann,