کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4724796 | 1639734 | 2006 | 19 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Mafic intrusions in southwestern Siberia and implications for a Neoproterozoic connection with Laurentia
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Mafic intrusions in southwestern Siberia and implications for a Neoproterozoic connection with Laurentia Mafic intrusions in southwestern Siberia and implications for a Neoproterozoic connection with Laurentia](/preview/png/4724796.png)
چکیده انگلیسی
Geochemical and geochronological studies reveal three distinct groups of Neoproterozoic to Early Paleozoic mafic intrusions in the Biryusa metamorphic massif of southwestern Siberia. Group 1 includes mafic sills that intruded Neoproterozoic passive-margin sediments, and were sourced from mantle-derived melts contaminated by crustal components. One sill yielded a plagioclase 40Ar-39Ar age of 741 ± 4 Ma, similar to ages of sills in the adjacent Sharyzhalgai metamorphic massif (all ages are ±2Ï or 95%). Group 2 is represented by north-trending dolerite dykes, one of which furnished a 40Ar-39Ar age of 612 ± 6 Ma. Group 2 dykes may have formed by passive asthenospheric upwelling and decompression during lithospheric stretching within the Neoproterozoic passive margin, a suggestion supported by the occurrence of coeval carbonatites and alkaline ultramafic rocks in the adjacent Sharyzhalgai massif. Group 3 consists of NW-trending dolerite dykes produced by melting of a lithospheric mantle source metasomatised by subduction-related fluids. Zircons from one Group 3 dyke provided a SHRIMP U-Pb zircon age of 511 ± 5 Ma, similar to the age of regional metamorphism during Early Paleozoic orogenesis. Our results show that mafic intrusions, broadly similar in age to the Franklin intrusions of northern Laurentia, exist along the southwestern margin of Siberia. Paleomagnetic data permit a reconstruction in which southern Siberia is located opposite northern Canada, but at a sufficient distance to accommodate other crustal blocks (e.g. northern Alaska, Chukchi Peninsula), and in which Group 1 intrusions could be distal products of the mid-Neoproterozoic Franklin mantle plume that affected northern Laurentia.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 147, Issues 3â4, 5 July 2006, Pages 260-278
Journal: Precambrian Research - Volume 147, Issues 3â4, 5 July 2006, Pages 260-278
نویسندگان
D.P. Gladkochub, M.T.D. Wingate, S.A. Pisarevsky, T.V. Donskaya, A.M. Mazukabzov, V.A. Ponomarchuk, A.M. Stanevich,