INTEGRATED MULTI-STRATIGRAPHIC INVESTIGATION OF THE LATE PERMIAN-EARLY TRIASSIC TERRESTRIAL SUCCESSION IN THE CATALAN PYRENEES (NE IBERIAN PENINSULA): THE COLL DE TERRERS SECTION

The Permian–Triassic boundary (PTB) around 252 Ma is still poorly understood in terrestrial settings, mainly due to a lack of suitable complete sections worldwide. This is particularly true along the Western Tethys region, located at Pangaea's equator, where continental successions are typically build-up of redbeds often characterized by a significant erosive gap at the base of the Triassic strata. Thus, the study of large, potentially complete terrestrial successions spanning the PTB might shed new light on the environmental and climatic conditions around the Permian mass extinction event and the subsequent Triassic ecosystem recovery.

Here, we present an integrated multi-stratigraphic investigation of the Coll de Terrers continental succession from the Catalan Pyrenees (NE Iberian Peninsula). The continental redbed successions were deposited in a long E-W extended narrow rift system (the Pyrenean Basin) and represent a nearly continuous sedimentary deposition as suggested by cyclostratigraphic analysis. Deposition evolved from meandering to playa-lake/ephemeral lacustrine environments (Upper Red Unit facies) and then again to meandering settings (Buntsandstein facies). Tetrapod ichnoassemblages suggest a late Permian age for the uppermost Permian units. Combined sedimentological, mineralogical and geochemical data allow us to infer a transition, in the uppermost Permian, from humid to semiarid conditions, in agreement with the overall aridification reported for the late Permian.

As already documented for other locations of equatorial Pangaea, the late Permian succession of Coll de Terrers was deposited under a monsoonal regime, in a low-energy setting (distal alluvial plain), with orbital forcing imprint recurrence conditions (i.e., potential eccentricity and long-term obliquity cycles). The potential record of the PTB in Coll de Terrers and in nearby sections like Coll de Creus and Sauvanyà is discussed. Preliminary results for these two sections are also presented.