气候变化领域集成服务门户(CCPortal): Paleomagnetism of Permo–Triassic volcanic units in northern Patagonia: are we tracking the final stages of collision of Patagonia?

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DOI	10.1007/s00531-018-01672-9
	Paleomagnetism of Permo–Triassic volcanic units in northern Patagonia: are we tracking the final stages of collision of Patagonia?
	Luppo T.; Martínez Dopico C.I.; Rapalini A.E.; López de Luchi M.G.; Miguez M.; Fanning C.M.
发表日期	2019
ISSN	14373254
起始页码	621
结束页码	647
卷号	108 期号:2
英文摘要	A paleomagnetic and geochronologic study was carried out on Late Permian-to-Early Triassic magmatic units exposed in the North Patagonian Massif, near the locality of Estancia La Esperanza (Río Negro Province, Argentina), to provide better paleogeographic and tectonic constraints on the evolution of Patagonia and its relations with Gondwana in the Late Paleozoic–Early Mesozoic. The study included the Late Permian (264 ± 2 Ma) Rhyolite Dome, the Collinao Dacite, for which we obtained a U–Pb zircon crystallization age of 253 ± 2 Ma, several basic dikes, that intrude older granite units (255 ± 2 Ma), and a swarm of acidic dikes for which an Early Triassic age had been previously assigned that we confirmed with a U–Pb zircon age of 244 ± 2 Ma. A paleomagnetic pole (C), computed on the basis of seven VGPs, was obtained for the Collinao Dacite and associated units (48.3°S, 349.9°E, N = 7, A95 = 15.1°). A single VGP for the somewhat older Rhyolite Dome falls close to that pole. A second paleomagnetic pole (A) which strongly disagrees with the C position was computed based on 12 VGPs from the same number of acidic dikes (87°S, 51.5°E, N = 12, A95 = 8.1°). The basic dikes, with ages bracketed between the dacitic and the rhyolitic dikes, yielded four VGPs, two of which are consistent with the C pole and the other two are close to the A pole. The C pole falls on a much older position (Late Carboniferous) on different Gondwana/South America reference paths, which is clearly anomalous based on its Late Permian age. The A pole, in turn, is consistent with the 250/240 Ma paleomagnetic poles in most reference paths for Gondwana/South America. Either regional tilting or rotation around a vertical axis to explain the anomalous C pole is unlikely considering the local geological evidence. A working model is presented to explain the discrepancy as due to around 30° CCW rotation of the whole North Patagonian Massif during the latest Permian and earliest Triassic, closing a V-shaped basin that separated it from southern Gondwana, as the final stages of collision of an allochthonous or para-autochthonous Patagonia terrane. This hypothesis is consistent with Late Permian-to-Early Triassic evidence of deformation in the Hespérides Basin as well as in northern Patagonia. Scarce previous paleomagnetic data from this region can be reconciled with this model, considering that they are very loosely constrained in age. © 2019, Geologische Vereinigung e.V. (GV).
英文关键词	Apparent polar wander path; Gondwana; La Esperanza volcanic rocks; Late Paleozoic; North Patagonian Massif
语种	英语
scopus关键词	apparent polar wander path; collision zone; geochronology; Gondwana; paleogeography; paleomagnetism; Permian-Triassic boundary; tectonic evolution; volcanic rock; Argentina; Patagonia; Rio Negro [Argentina]; Esperanza
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/147867
作者单位	Facultad de Ciencias Exactas y Naturales, Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires (IGEBA), Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Instituto de Geocronología y Geología Isotópica (INGEIS), Ciudad Universitaria, Pabellon INGEIS, Buenos Aires, Argentina; School of Earth Sciences, Australian National University, Canberra, Australia
推荐引用方式 GB/T 7714	Luppo T.,Martínez Dopico C.I.,Rapalini A.E.,等. Paleomagnetism of Permo–Triassic volcanic units in northern Patagonia: are we tracking the final stages of collision of Patagonia?[J],2019,108(2).
APA	Luppo T.,Martínez Dopico C.I.,Rapalini A.E.,López de Luchi M.G.,Miguez M.,&Fanning C.M..(2019).Paleomagnetism of Permo–Triassic volcanic units in northern Patagonia: are we tracking the final stages of collision of Patagonia?.International Journal of Earth Sciences,108(2).
MLA	Luppo T.,et al."Paleomagnetism of Permo–Triassic volcanic units in northern Patagonia: are we tracking the final stages of collision of Patagonia?".International Journal of Earth Sciences 108.2(2019).