کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8912634 | 1639568 | 2018 | 53 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The eastern boundary of Sveconorwegian reworking in the Baltic Shield, defined by 40Ar/39Ar geochronology across the southernmost Sveconorwegian Province
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
New 40Ar/39Ar dates of hornblende, biotite and muscovite from 13 localities along a 130â¯km transect in southern Sweden provide insight into the cooling and exhumation history during Sveconorwegian orogeny, from 970 to 880â¯Ma. The Eastern Segment represents Baltican continental crust underthrust below the western Sveconorwegian terranes at 990-970â¯Ma. The western part of the Eastern Segment consists of amphibolite- to granulite-facies pervasively deformed gneisses, in which hornblende and biotite 40Ar/39Ar dates between 901 and 889â¯Ma record the cooling and exhumation through 530-330â¯Â°C. In the easternmost part of the orogen is a c. 25â¯km wide boundary zone characterized by non-penetrative greenschist- to amphibolite-facies deformation zones. There, muscovite apparent ages range from 882 to 902â¯Ma, biotite from 892 to 906â¯Ma, and hornblende from 1.37 to 1.47â¯Ga, meaning that muscovite and partly biotite record Sveconorwegian overprint, while amphibole was disturbed. Several biotite samples record ages in the interval 0.9-1.4â¯Ga, reflecting excess Ar components. East of the Sveconorwegian Province, in the Blekinge-Bornholm Province, hornblende and mica apparent ages spread between 1.13 and 1.41â¯Ma, implying that neither mineral underwent complete Sveconorwegian resetting. The data pattern reflects that the Eastern Segment experienced slow cooling (â¼3â¯Â°C/Ma) from peak metamorphism of 800-700â¯Â°C at 980-960â¯Ma to 900â¯Ma, when significant cooling though greenschist-facies conditions set in (â¼26â¯Â°C/Ma). This cooling was related to tectonically driven extension, accommodated by greenschist-facies shear zones along the eastern boundary zone.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 307, April 2018, Pages 201-217
Journal: Precambrian Research - Volume 307, April 2018, Pages 201-217
نویسندگان
Jan Ulmius, Charlotte Möller, Laurence Page, Leif Johansson, Morgan Ganerød,