کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8912775 | 1639573 | 2017 | 88 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Evidence for Neoarchean Ni-Cu-bearing mafic intrusions along a major lithospheric structure: A case study from the south Rae craton (Canada)
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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
Deformed and metamorphosed mafic to ultramafic intrusive rocks are common along and adjacent to the Snowbird Tectonic Zone, a major Paleoproterozoic structure separating the Rae and Hearne cratons. On the Rae side of this major lithospheric structure, we investigated a series of mafic bodies that intrude high-grade paragneiss and are associated with Ni-Cuâ¯Â±â¯PGE mineralization. By linking field observations, geochronology and metamorphic petrology, our results indicate Archean (â¼2.63â¯Ga) crystallization ages for these mafic intrusions over a minimum along-strike extent of â¼500â¯km and a later high-temperature (â¼820â¯Â°C and â¼7.5â¯kbar), Paleoproterozoic metamorphic overprint at tâ¯<â¯1.94â¯Ga. The youngest reproducible ages of detrital zircon from the host paragneiss indicate a maximum depositional age of â¼2.73â¯Ga for the paragneiss. These results indicate that the sedimentary rocks hosting the mineralized mafic intrusions are older than the mixed siliciclastic and carbonate sedimentary units previously described along the Snowbird Tectonic Zone (<2.07â¯Ga). Furthermore, in two localities (Thye and Yotin-Shagory lakes, in Northwest Territories and northern Saskatchewan), zircon from both the mafic and pelitic samples exhibit an unusual within-run fluctuation in the lead isotope signal during SHRIMP analysis, suggesting inhomogeneous redistribution of radiogenic Pb within the crystal lattice. Redistribution is interpreted to have occurred during the â¼1.94-1.90â¯Ga tectonometamorphic event. This behaviour, documented only in â¼10 (Ultra)High-Temperature localities worldwide, has not been observed in the other two studied localities (Currie and Axis lakes in northern Saskatchewan), suggesting either i) a different metamorphic history or ii) different re-crystallization processes occurring during the Paleoproterozoic high-temperature evolution (or a combination of the two). Our data indicate that (U)HT metamorphism and the absence of a fluid/melt phase are not a requirement for lead redistribution in zircon.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 302, November 2017, Pages 312-339
Journal: Precambrian Research - Volume 302, November 2017, Pages 312-339
نویسندگان
D. Regis, P. Acosta-Gongora, W.J. Davis, B. Knox, S.J. Pehrsson, E. Martel, L. Hulbert,