Provenance analysis of Lower Palaeozoic siliciclastic rocks of the Southwestern Iberia (Ossa-Morena Zone) : distal shelf deposition on the North Gondwana passive margin
| Autor: | U. Linnemann, C. Lopes, Martim Chichorro, M. Hofmann, Ana Rita Solá, José Silva, Manuel Francisco Pereira |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Provenance
Paleozóico inferior Gondwana Paleozoic Câmbrico médio Península Ibérica (Sudoeste) 010502 geochemistry & geophysics 01 natural sciences Devonian Devónico inferior Paleontology Basement (geology) Rochas siliciclásticas Geocronologia Ordovician Siliciclastic 010503 geology Zona de Ossa-Morena Zircão Geology Ordovícico 0105 earth and related environmental sciences Zircon Câmbrico superior |
| Zdroj: | Springer Geology ISBN: 9783319043630 |
| Popis: | U–Pb dating of detrital zircons from the lower Palaeozoic siliciclastic rocks of southwestern Iberia (the Ossa–Morena Zone or OMZ: comprising the Fatuquedo, Ossa, Colorada, and Terena formations) shows that sedimentation during the middle–late Cambrian to Early Devonian was marked by slight variations in the source areas, involving the denudation of crustal blocks with similar zircon-forming events typical of North Gondwana and the absence of volcanism younger than ca. 470 Ma. The potential source areas of the middle–upper Cambrian to Lower Devonian sediments of the basins of the OMZ could be the Neoproterozoic basement of the OMZ (the Serie Negra) intruded by Cambrian and Early Ordovician plutonic rocks, and/or the lower Palaeozoic sedimentary sequences of the OMZ with Cambrian and Early Ordovician volcanics. In the oldest siliciclastic rocks, the most relevant populations of detrital zircons have Cryogenian and Ediacaran ages (the Ossa and Fatuquedo formations). Futhermore, in the youngest siliciclastic rocks, in addition to Cryogenian and Ediacaran zircon grains there are relevant clusters of Cambrian and Tonian ages (the Colorada Formation). Cambrian and Ordovician zircon ages found in the Lower Devonian greywackes (the Terena Formation) suggest intense denudation of the OMZ during the Early Devonian. No evidence was found of sources outside North Gondwana. The lack of zircon-forming events younger than ca. 470 Ma seems to indicate that the middle–upper Cambrian to Lower Devonian siliciclastic rocks of southwestern Iberia were deposited on a distal shelf of the North Gondwana passive margin related to the opening of the Rheic Ocean and in the absence of magmatic activity. |
| Databáze: | OpenAIRE |
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