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DOI	10.1007/s00531-020-01926-5
	Permo–Triassic metamorphism in the Mérida Andes; Venezuela: new insights from geochronology; O-isotopes; and geothermobarometry
	Tazzo-Rangel M.D.; Weber B.; Schmitt A.K.; González-Guzmán R.; Cisneros de León A.; Hecht L.
发表日期	2020
ISSN	14373254
英文摘要	Although there is a consensus about Pangea assemblage in northwestern Gondwana spanning from the Late Carboniferous to the Early Permian, the tectonics of the Permo–Triassic period, including the onset of Pangea breakup, is still controversial. In this context, three regional tectonic features need to be considered: (1) The Ouachita-Marathon-Sonora suture, (2) east-dipping subduction of the Panthalassa oceanic crust beneath Gondwana, and (3) an extensional setting documented in Colombia, Ecuador, and México suggesting Pangea breakup at ca. 240–220 Ma. A chemical, isotopic, and geochronological dataset is presented in this contribution to constrain the effects of these tectonic processes in the metamorphic basement of the Mérida Andes in western Venezuela. U–Pb Secondary Ion Mass Spectrometry analyses on unpolished surfaces of zircons from orthogneisses yielded an average age of 251 ± 4 Ma. The corresponding δ18O values suggest metamorphic recrystallization of zircon instead of high-T fluid interaction. Rb–Sr and Sm–Nd geochronology in white mica and garnet yielded ages of 234 ± 3 Ma and 249 ± 2 Ma, respectively, whereas a younger Rb–Sr date of 197 ± 1 Ma was obtained from biotite. U–Pb and Sm–Nd ages constrain the latest Permian–earliest Triassic metamorphism in the Mérida Andes at 251 ± 4 Ma. Geothermobarometry data suggest amphibolite-facies peak metamorphic conditions at ~ 685 °C and ~ 6.0 kbar. Metamorphism might be related to post-orogenic collapse, after the collision of Gondwana and Laurentia to form Pangea. Rb–Sr ages suggest retrogression and cooling, possibly caused by thermal relaxation of a tectonically overthickened crust and onset of extensional setting, followed by Pangea breakup during the Late Triassic–Early Jurassic. © 2020, Geologische Vereinigung e.V. (GV).
英文关键词	Geothermobarometry; Multi-isotopic system geochronology; Mérida Andes; Pseudosection modeling; Zircon oxygen isotopes
语种	英语
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147759
作者单位	Departamento de Geología, División de Ciencias de la Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana #3918, Ensenada, B.C. 22860, Mexico; Institute für Geowissenschaften, Heidelberg University, Im Neuenheimer Feld 234-236, Heidelberg, 69120, Germany; Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, Berlin, 10115, Germany
推荐引用方式 GB/T 7714	Tazzo-Rangel M.D.,Weber B.,Schmitt A.K.,等. Permo–Triassic metamorphism in the Mérida Andes; Venezuela: new insights from geochronology; O-isotopes; and geothermobarometry[J],2020.
APA	Tazzo-Rangel M.D.,Weber B.,Schmitt A.K.,González-Guzmán R.,Cisneros de León A.,&Hecht L..(2020).Permo–Triassic metamorphism in the Mérida Andes; Venezuela: new insights from geochronology; O-isotopes; and geothermobarometry.International Journal of Earth Sciences.
MLA	Tazzo-Rangel M.D.,et al."Permo–Triassic metamorphism in the Mérida Andes; Venezuela: new insights from geochronology; O-isotopes; and geothermobarometry".International Journal of Earth Sciences (2020).