کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4722314 1639589 2016 19 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A late Paleoproterozoic key pole for the Fennoscandian Shield: A paleomagnetic study of the Keuruu diabase dykes, Central Finland
ترجمه فارسی عنوان
یک قطب کلیددار پایلوپروتروزیوسیال قدیمی برای سپر افسانه ای: یک مطالعه پالئومغناطیس دایکای دیاباز کیوروو، فنلاند مرکزی
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی


• A late-Paleoproterozoic paleomagnetic key pole for Baltica.
• New isotope ages for Keuruu diabase dykes.
• Asymmetry in dual polarity magnetization attributed to an unremoved secondary component.
• Fennoscandian Shield positions at low latitude at 1.87 Ga.

We present an updated paleomagnetic pole and a new isotope age for the late Paleoproterozoic (Svecofennian) diabase dykes from Keuruu, Central Finland. The paleomagnetic results reveal a dual-polarity remanent magnetization with asymmetry, which we explain by an unremoved secondary component contaminating both normal (N) and reversed (R) vectors. The ChRM is carried by magnetite, most of which are primary grains crystallized from basaltic magma. The primary nature of the ChRM is further supported by positive baked contact tests. An R polarity dyke shows a U-Pb concordia age of 1870 ± 9 Ma. Zircons from another dyke of N polarity reveal a mean Pb-Pb age of 1867 ± 8 Ma. The combined N and R mean ChRM direction is D = 340.4°, I = 35.2°, α95 = 5.8°, k = 31.3, N = 21 dykes (yielding a paleomagnetic pole of Plat = 45.7°, Plon = 230.9°, A95 = 5.5°. This positions the Fennoscandian Shield at low latitudes (19.4°), and aligns with Superior Craton in a way that would naturally proceed into the 1.8–1.2 Ga NENA (North Europe–North America) configuration. Paleosecular variation analysis of N polarity dykes is consistent with the low latitude position of Baltica.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 286, November 2016, Pages 379–397
نویسندگان
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