کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4729592 1356544 2006 19 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Petrology and geochemistry of the Neoproterozoic Nguba and Kundelungu Groups, Katangan Supergroup, southeast Congo: Implications for provenance, paleoweathering and geotectonic setting
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Petrology and geochemistry of the Neoproterozoic Nguba and Kundelungu Groups, Katangan Supergroup, southeast Congo: Implications for provenance, paleoweathering and geotectonic setting
چکیده انگلیسی

The Nguba and Kundelungu Groups constitute the middle and upper parts of the Neoproterozoic Katangan Supergroup, respectively, and consist of conglomerates, sandstones, mudrocks and carbonates. During deposition, the Katangan basin received sediments originating from both northern and southern sources. The Nguba and Kundelungu Groups siliciclastic rocks have elemental abundances and ratios suggestive of a relatively felsic TTG source, although slightly more mafic compositions occur in the Nguba Group and the overlying “Petit Conglomérat” Formation at the base of the Kundelungu Group. Modal compositions of the Nguba Group rocks indicate a basement uplift provenance, and geochemical parameters indicate the source of both the Nguba and Kundelungu Groups had an active continental margin character.Source area weathering was moderate in the Nguba Group. Low Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) indices and relatively uniform chemical compositions of the “Grand Conglomérat” and the “Petit Conglomérat” Formations lying respectively at the bases of the Nguba and Kundelungu Groups are compatible with deposition in a cool or frigid climate, and support their presumed petrographic based glaciogenic origin. High CIA and PIA indices in Upper Kalule rocks in the middle part of the Kundelungu Group point to the intensification of source weathering, possibly under tropical to subtropical climate under steady state conditions. Geochemical similarities between the Nguba Group and the “Petit Conglomérat” are compatible with a change from an extensional setting to compression, with derivation of the “Petit Conglomérat” by reworking of the underlying units during basin inversion. Change in provenance signatures and weathering indices in the Upper Kalule Formation may reflect reduced tectonism and resumption of supply of more weathered extrabasinal detritus, similar to that which fed the basal Roan Group.Overall the data suggest derivation mainly from pre-Katangan Proterozoic sources with continental arc characteristics. The adjacent Paleoproterozoic Ubendian Belt, particularly the Bangweulu block calcalkaline plutonic and volcanic province, is a suitable candidate as the source for the Nguba and Kundelungu Group sedimentary rocks. However, Mesoproterozoic and Archaean terrains have also contributed a minor component to the basin.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of African Earth Sciences - Volume 44, Issue 1, January 2006, Pages 97–115
نویسندگان
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