Sudden changes in fluvial style across the Permian−Triassic boundary in the eastern Iberian Ranges, Spain: Analysis of possible causes

Abstract

The sedimentary record of the Late Permian and Early Triassic of the eastern Iberian Ranges shows four major, sudden, or very rapid, vertical changes in fluvial style. The Late Permian sedimentary cycle starts with the Boniches Formation, of alluvial fan-braided fluvial origin, which grades vertically over within a few metres into the A1cotas Fonnation, deposited by low to high sinuosity, avulsion-prone rivers with extensive floodplains. The A1cotas Fonnation contains ca1cimorphic soils, plant remains and pollen and spore assemblages. However, the upper third of the unit is devoid of all organic remains and soils and is characterized by a dominant red colour, the sandstone levels were deposited by high-sinuosity, meandering rivers. This global cause was probably die-off of plant cover over extensive areas of the catchment, related to the end of the * Corresponding author. Tel.: +34 913974818; fax: +34 913944808.E-mail address: aarche@geo.ucm.es (A. Arche).Pennian mass extinction and possibly related to the emplacement of the West Siberian basaltic Large Igneous Province (LIP), responsible for drastic atmospheric and marine changes.

Integrated multi-stratigraphic study of the Coll de Terrers late Permian–Early Triassic continental succession from the Catalan Pyrenees (NE Iberian Peninsula): A geologic reference record for equatorial Pangaea

“…3G-I, 8). A similar energetic increase of the sedimentary style has been documented in the Permian-Triassic transition of the Iberian Basin (Arche and López-Gómez, 2005), Russia (Newell et al, 2010;Benton and Newell, 2014), central India (Chakraborty and Sarkar, 2005), South Fig. 7.…”

Structural style and evolution of a Late Triassic rift basin in the Central High Atlas, Morocco: controls on sediment deposition

“…The contact between the lower and middle members of the Oukaimeden Formation (F5) is marked by an extensive erosional surface, which is overlain by very coarse sandstone or conglomeratic deposits. A similar unconformity has been described in other Triassic basins along the Atlantic margins (Olsen et al 2000;Arche and López-Gómez 2005;Mader 2005). It has been suggested by previous workers that this boundary is due to a regional tectonic event which led to the reactivation of major fault systems (Olsen et al 2000), which increased relief and run-off, which produced the erosional surface and enhanced input of coarse-grained sediments into the basin.…”

Paleoecological and paleoenvironmental changes during the continental Middle–Late Permian transition at the SE Iberian Ranges, Spain

“…However, in the formation of certain types of laminar calcretes, the activity of root systems and other micro-organism is es sential (Wright et aI., 1988;Jones, 1992;Mack and James, 1994), and therefore humid conditions during some part of the year, suitable for this kind of vegetation, cannot be ruled out in the lower part of IS . This possibility is supported by a large number of multi-storey bodies in the infilling of channels, with noticeable reac tivation surfaces and erosive bases (Arche and L6pez-G6mez, 2005). Moreover, in the Rodeno paleosols of this lower part of the IS, the Bk depth is greater than in the upper part of the IS.…”