%0 Journal Article
%A López Gómez, José
%A Arche, Alfredo
%A Marzo Carpio, Mariano
%A Durand, Marc
%T Stratigraphical and palaeogeographical significance of thecontinental sedimentary transition across the Permian–Triassicboundary in Spain
%D 2005
%@ 0031-0182
%U https://hdl.handle.net/20.500.14352/50275
%X The Permian–Triassic transition, a time of phenomenal palaeoenvironmental and palaeogeographical change, represents thelargest episode of mass extinctions known to palaeontologists. This episode is, however, very poorly understood, and a lack ofsediments and palaeontological data, particularly in the continental record, is a feature common to every basin. Despitecompelling information on the continental Permian–Triassic boundary (PTB) emerging from recent efforts evaluating vertebrateevolution, fungal events and isotope curves, results are still insufficient to make any valuable correlations among continentalbasins and are even less appropriate for relating sediments of continental to those of marine origin. The present report discussesand attempts to locate the PTB in the basins of Iberia and Balearic Islands through an analysis of the palaeontological andsedimentary record across the Permian–Triassic transition. The aim of the paper is to contribute to our present knowledge of thepalaeogeographical and stratigraphical significance of the Permian and Triassic continental units of Western Europe.The present-day Iberian Ranges, Catalonian Ranges and Balearic Islands hold the most complete Late Permian–EarlyTriassic sedimentary record in Iberia. This record consists of alluvial sediments, mainly of braided fluvial systems, correspondingto the bSaxonianQ and Buntsandstein facies. All the units examined so far have been dated through palynological associations.The two bSaxonianQ facies formations are of Thuringian age, although the lower one shows some palynological elements ofAutunian affinities. The Buntsandstein units range from Thuringian to Anisian in age, there being no evidence up to now ofthe Scythian in Iberia. The exact position of the PTB in Iberia is up to now impossible to pinpoint with the precision of themarine series. Sedimentary characteristics and palynological data in the Iberian Ranges point that it lies at the sedimentaryinterval, 10 to 30 m thick, formed by the upper member of the La Hoz del Gallo Formation and the lowermost beds of theCan˜ izar Formation or its time equivalent the Prades and Eramprunya´ units in the Catalonian Ranges and the Asa´ and B-1 inthe Balearic Islands. We compare a normalized standard Late Permian–Middle Triassic column of the Iberian Ranges withstandards from Western and Central Europe and the Southern Urals using recent Permian time scales. A palaeogeographic essay map of the Permian–Triassic transition is provided for the Iberian Plate. The plate was located in a northern subtropicalposition, 200–400 km from the westernmost Tethys coast, as part of the Central Pangean Mountain Range comprised of theAppalachian–Mauretanide–Variscan orogenic belts of estimated altitudes 2000–4000 m. Based on this palaeogeographiclocation, sedimentary characteristics and the main wind flows established for the Tethys, we can infer conditions of highprecipitation dominated by monsoon and seasonal regimes with isolated semiarid areas for the Iberian Plate during thetransition.
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