کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5785506 1640173 2017 14 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mineral composition and geochemistry of the Upper Cretaceous siliciclastics (Nubia Group), Aswan District, south Egypt: Implications for provenance and weathering
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Mineral composition and geochemistry of the Upper Cretaceous siliciclastics (Nubia Group), Aswan District, south Egypt: Implications for provenance and weathering
چکیده انگلیسی
The statistical examination had revealed that the chemical constituents are loaded on three main geochemical trends; the siliceous, the argillaceous and the ferruginous. The enrichment factor shows that the geochemical behavior of the major and trace elements is uniform throughout the sandstones and mudstones of the Abu Aggag Formation. A significant geochemical contrast is documented between the sandstones and mudstones of both the Timsah and the Um Barmil formations. The provenance - critical elemental ratios Ti/Nb and Ti/Y are nearly constant throughout the sandstones and mudstones of the Abu Aggag Formation, and they fall within the range of granitic-granodioritic composition. The Timsah sandstones have Ti/Nb and Ti/Y ratios that are consistent with those of the Abu Aggag rocks, suggesting a similar provenance. These elemental ratios are extremely higher in the Timsah mudstones, reflecting a great influx of mafic material. The Um Barmil sandstones exhibit exceedingly dispersed values of Ti/Nb and Ti/Y, reflecting their derivation from large catchment's areas of different rock types with the eroded products being mixed in various relative proportions. The Ti/Nb and Ti/Y of the Um Barmil mudstones are closely akin to those of the Timsah mudstones suggesting analogous source. The chemical index of alteration (CIA) and the A-CN-K relation, together with the mineral composition, indicate that the siliciclastic rocks throughout the whole succession were derived mainly from deeply weathered detritus under steady-state weathering conditions. Recycling is limited in the Abu Aggag Formation and increases upwards to be more common in the Um Barmil rocks.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of African Earth Sciences - Volume 135, November 2017, Pages 82-95
نویسندگان
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