کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4694187 | 1636904 | 2008 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Defining the southern margin of Avalonia in the Pontides: Geochronological data from the Late Proterozoic and Ordovician granitoids from NW Turkey
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We provide new isotopic data from the Pontides, which substantiate the presence of a Cadomian basement with latest Proterozoic granitoids but also show the existence of Ordovician intrusives. Before the opening of the Black Sea, the Pontides formed a Palaeozoic orogenic belt at the margin of the East European Platform (Baltica) in an analogous position to the Variscan terranes in the central Europe. The Pontides consist of three terranes: The Strandja terrane has a Variscan basement with Carboniferous and Permian granitoids and an epicontinental Triassic to Jurassic sedimentary cover. The I.stanbul terrane has a Cadomian basement overlain by a sedimentary sequence of Ordovician to Carboniferous age. It underwent contractional deformation during the Late Carboniferous. The Sakarya terrane is characterized by Carboniferous high temperature metamorphism and plutonism. The boundary between the I.stanbul and Sakarya terranes forms a complex tectonic zone several tens of kilometres wide. The new age data come from this boundary zone in the Armutlu peninsula in northwest Turkey. Metagranitoids, which intrude amphibolites in the Armutlu peninsula, give latest Proterozoic and Ordovician U-Pb zircon laser ablation MC-ICP-MS and Pb-Pb evaporation ages. The latest Proterozoic (ca. 570Â Ma) granitoids are similar in age to those reported previously from the basement of the I.stanbul terrane; they all form part of the widespread Pan-African granitoid plutonism on the margins of Gondwana. The Mid to Late Ordovician granitoids (460Â Ma), on the other hand, probably have formed during the rifting of the I.stanbul terrane away from Gondwana during the opening of the Rheic ocean. In terms of the tectonic position, stratigraphy and geological evolution, the I.stanbul and Sakarya terranes are comparable to the Avalonia and the Armorican terrane assemblage in central Europe, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tectonophysics - Volume 461, Issues 1â4, 1 December 2008, Pages 252-264
Journal: Tectonophysics - Volume 461, Issues 1â4, 1 December 2008, Pages 252-264
نویسندگان
Aral I. Okay, Erdin Bozkurt, Muharrem Satır, Erdinç YiÄitbaÅ, Quentin G. Crowley, Cosmas K. Shang,