کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4728695 1640204 2015 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The oldest rock of Ivory Coast
ترجمه فارسی عنوان
قدیمی ترین سنگ ساحل عاج
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
چکیده انگلیسی


• The gneiss of Balmer is a fairly peraluminous TTG with characters that are similar to the average TTG.
• The zircon population corresponds to a high-temperature type with clear magmatic zoning.
• We obtain two ages: 3207 ± 7 Ma (magmatic protolith) and 3155 ± 17 Ma (gneissification).

The tonalitic gneiss of Balmer (TGB), in the SASCA area of south-western Ivory Coast, previously dated at 3141 ± 2 Ma using the single zircon evaporation method, is regarded as a relic of Archean rock within the Paleoproterozoic (Birimian) formation of the West African Craton (WAC). We present new geochronological data for the TGB using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method. We obtain a U–Pb age of 3207 ± 7 Ma for abundant zircons extracted from the tonalitic gneiss, and interpret this age as that of the magmatic protolith because of the igneous-type homogeneous zircon population. Certain magmatic zircon edges and some round zircons define an upper intercept age of 3155 ± 17 Ma which could represent overgrowths during gneissification. It appears that the TGB was not affected by the events posterior to its genesis, i.e. the Liberian (2.9–2.7 Ga) and Eburnean (2.4–2.0 Ga) events. Additionally, the TGB proves to be a juvenile Leonian rock, as indicated by the Nd model age of 3456 Ma, and could also constitute the protolith of the granulitic grey gneisses and charnockites of the Man area, which are 150–400 Ma younger.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of African Earth Sciences - Volume 103, March 2015, Pages 65–70
نویسندگان
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