Early Triassic Fluvial–Aeolian Interaction in the Catalan Ranges (Northeastern Spain) and Its Palaeogeographical Significance for the Western Tethys

Abstract

The Early Triassic was still marked by the general perturbations related to the drastic palaeoenvironmental changes that occurred around the Permian–Triassic transition. These perturbations affected both marine and continental environments and were caused by events such as massive volcanism from the Siberian Traps and the consequent general geochemical anomalies that caused a widespread episode of mass mortality. When compared with the marine record, studies of continental rocks are scarce due to the decimated fossil record and important hiatuses. Some of these studies have been conducted in Central Europe series and in isolated areas of Antarctica, the Urals, and South Africa. During the late Early Triassic (Spathian), Central Europe was dominated by significantly dry conditions that allowed aeolian dune fields to develop. Southwards of this vast area, conditions were changing towards the more humid conditions that affected northern Africa. This chapter focuses on the Catalan Ranges, northeastern Spain, where exceptional outcrops of continental rocks of Early–Middle Triassic age allow detailed sedimentary and palaeoenvironmental studies to be made. These studies offer new information about the palaeogeography of the western Tethys area, the climatic variations south of Central Europe, and the first steps of life recovery in this area after the Permian–Triassic boundary crisis. Data in this chapter provide the basis for a sedimentological interpretation of the Lower Triassic sediments of the Catalan Ranges, where aeolian deposits are more important than previously thought. In addition, a new palaeogeography of the northeastern Iberian Peninsula is presented, which shows that fluvial deposits were dominant in the Iberian Ranges, but in the Ebro and Catalan Basin, aeolian deposits predominated in depressions among topographic highs of Palaeozoic rocks, receiving far less fluvial input and probably of local origin. This arrangement of facies is well known in Early Triassic basins of Western and Central Europe, but until now has been overlooked in the Iberian Peninsula.