U-Pb detrital zircon provenance of metasedimentary rocks from the Cear谩 Central and M茅dio Corea煤 Domains, Borborema Province, NE-Brazil: Tectonic implications for a long-lived Neoproterozoic active continental margin

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• 作者：Carlos E. Ganade de Araujo^a ; ^b ; ^{caegeo@gmail.com} ; Umberto G. Cordani^a ; Miguel A.S. Basei^a ; Neivaldo A. Castro^c ; Kei Sato^a ; Walter M. Sproesser^a
• 关键词：Detrital zircon ; Provenance ; Borborema Province
• 刊名：Precambrian Research
• 出版年：2012
• 期刊代码：75_03019268
• 类别：ear
• 出版时间：June, 2012
• 卷：206-207
• 期：Complete
• 页码：36-51
• 文件大小：3298 K

摘要

U-Pb geochronological analyses have been acquired on detrital zircon grains collected from 14 samples in the Cear谩 Central (CCD) and M茅dio Corea煤 (MCD) tectonic domains, separated by the Transbrasiliano-Kandi Lineament (TKL) on the Borborema Province. To the West of this lineament, the basement of the MCD has a tectonic affinity with the West African and S茫o Luis Cratons, where Paleoproterozoic rocks predominate. Within this area, three samples of the S茫o Joaquim quartzite yielded Paleoproterozic and Archean ages only, with the youngest ²⁰⁶Pb/²⁰⁷Pb ages at ca. 1750 Ma. However, the Goiabeira Formation schist, in the same domain, yielded younger ²⁰⁷Pb/²³⁵U ages around 720 Ma, with predominance of zircons within the 750-1100 Ma interval. To the East of the TKL, the Borborema Province correlates well with the Transaharan Belt of West Africa, where the Paleoproterozoic-Archean basement was affected by a strong tectonic imprint of the Neoproterozoic Brasiliano-Pan African orogeny. Three samples from the region between the TKL and the Tamboril-Santa Quit茅ria granitic-migmatitic Complex (TSQgmC) yielded younger ²⁰⁷Pb/²³⁵U concordant ages (ca. 660-700 Ma), which are 20-60 Ma younger than those of the Goiabeira Formation. Further east within the CCD, eastern of the TSQgmC, six samples yielded two distinct detrital patterns, with some samples showing younger concordant ages (ca. 900 and 750 Ma), while others demonstrate a strong Paleoproterozoic source component with zircons older than ca. 1500 Ma. Finally, one sample of the post-collisional extensional Ja铆baras Trough, within the main axis of the TKL, yielded a maximum deposition age of ca. 540 Ma, with a strong source component ranging from 540 to 640 Ma, derived mainly from the TSQgmC. Evidence of a large ocean basin prior to 800 Ma, along the vicinity of the TKL, is well established in Central Brazil and West Africa. We believe that the strong source component at around 800-700 Ma, and possibly also the older ones at ca. 1000 Ma, were shed from magmatic arc systems developed at the margins of the ancient continent which makes up the basement of the Borborema Province. Abrupt cessation of the detrital zircons input at ca. 650 Ma, suggests a change in the tectonic regime at this time, marking the onset of collisional tectonics and main metamorphism in the province. This fact is supported by the ages spanning the 640-590 Ma interval found in the metamorphic domains of the studied zircons which are partially synchronous with the development of the main tectonic and magmatic stages of the TSQgmC.