کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4722395 1639599 2016 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
New isotopic constraints on age and origin of Mesoarchean charnockite, trondhjemite and amphibolite in the Ntem Complex of NW Congo Craton, southern Cameroon
ترجمه فارسی عنوان
محدودیت های جدید ایزوتوپیک بر سن و منشا چارناکیت مازورا، تاندونیمیت و آمفیبولیت در مجتمع مادری نیو کنگو کراتون، جنوب کامرون
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی


• Charnockite, TTG and amphibolite in Ntem Complex formed at ∼2.92 and 2.87–2.86 Ga, respectively.
• Zircon O–Hf isotopes suggest different sources for charnockitic and TTG suite rocks.
• Charnockites may be genetically related to extensive mantle plume activity at 2.92 Ga.
• TTG formed by high-P melting of ancient crustal sources triggered by synchronous mafic magmatism.
• A ∼3.8 Ga-old ancient proto-crust may have existed in the NW Congo Craton.

Integrated in-situ analyses of zircon U–Pb ages and Hf–O isotopes are reported for charnockite, trondhjemite and associated amphibolite in the Archean Ntem Complex of the NW Congo Craton, southern Cameroon. The charnockite crystallized at ∼2.92 Ga, coincident with the timing of extensive occurrence of high-temperature magmatism possibly related to mantle plume activity worldwide. They are characterized by zircon δ18O values of ∼5.9‰ and ɛHf(t) values of ∼0.0, with Hf model ages of ∼3.5–3.3 Ga. On the basis of the new isotopic and literature data we suggest that the charnockites were generated by partial melting of a Paleoarchean mafic crustal source possibly triggered by 2.92 Ga mantle plume activity. The trondhjemite and associated amphibolite protolith crystallized synchronously at ∼2.87–2.86 Ga. The trondhjemite exhibits zircon δ18O values of ∼6.0‰ and negative ɛHf(t) values of ca. −3.7, with Hf model ages of ∼3.8–3.5 Ga, whereas the amphibolite has positive zircon ɛHf(t) values of ∼2.3 and δ18O values of ∼4.6‰, lower than that (∼5.3‰) of zircons from juvenile mantle-derived magmas. The trondhjemite was most likely generated by high-pressure partial melting of an Eoarchean crustal protolith possibly triggered by the synchronous mafic magmatism. An ancient ∼3.8 Ga-old proto-crust may have existed in the NW Congo Craton.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 276, May 2016, Pages 14–23
نویسندگان
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