کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4730288 1356745 2015 17 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Petrological and geochemical features of the Jingtieshan banded iron formation (BIF): A unique type of BIF from the Northern Qilian Orogenic Belt, NW China
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Petrological and geochemical features of the Jingtieshan banded iron formation (BIF): A unique type of BIF from the Northern Qilian Orogenic Belt, NW China
چکیده انگلیسی


• The studied BIFs are primarily controlled by Fe, Si, CO32− and Ba.
• Dominated sources are high-temperature hydrothermal solutions.
• The whole ocean anoxia is not required when Jingtieshan BIFs formed.
• The Jingtieshan BIFs are a unique type of BIF.

The Jingtieshan banded iron formation (BIF) is located in the Northern Qilian Orogenic Belt (NQOB) in NW China. The BIFs are hosted in Mesoproterozoic Jingtieshan Group, a dominantly clastic-carbonate sedimentary formation, and was metamorphosed to lower greenschist facies. The Jingtieshan BIFs include oxide-, carbonate- and mixed carbonate–oxide facies, and consist of alternating iron-rich and silica-rich bands. The BIFs are composed essentially of specularite and jasper, with minor carbonate minerals and barite. The SiO2 + Fe2O3 content is markedly high in the oxide facies BIF, followed by FeO, CO2 and Ba, with the other elements usually lower than 1%, suggesting that the original chemical sediments were composed of Fe, Si, CO32− and Ba. The positive correlation between Al2O3, TiO2 and Zr in the BIFs indicates that these chemical sediments incorporate minor detrital components. Oxide facies BIF shows low HFSE, low ∑REE and low Y/Ho. The Post Archean Australian Shale-normalized REE patterns for Jingtieshan BIFs are characterized slight LREE depletion, strong positive Eu anomalies and lack of significant negative Ce anomalies. Siderite in the carbonate- and mixed carbonate–oxide facies BIF shows negative δ13C values varying from −8.4‰ to −3.0‰, and δ18O values show a range of −16.6‰ to −11.7‰. The geochemical signatures and carbon–oxygen isotopes suggest origin from high-temperature hydrothermal fluids with weak seawater signature for the sediments of Jingtieshan BIFs. The absence of negative Ce anomalies and the high Fe3+/∑Fe ratios of the oxide facies BIF do not support ocean anoxia. In contrast to the three main types (Algoma-, Superior- and Rapitan-type) of global BIFs, the Jingtieshan BIFs represent a unique type with features similar to those of sedimentary-exhalative mineralization.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Asian Earth Sciences - Volume 113, Part 3, 1 December 2015, Pages 1218–1234
نویسندگان
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