Could acidity be the reason behind the Early Triassic biotic crisis on land?

Abstract

In recent years there is growing evidence of the importance of the Smithian-Spathian (Early Triassic) ecological crisis to explain the delayed recovery of life after the Permian-Triassic Boundary mass extinction. This study focuses on sedimentary continental rocks of middle Permian to Middle Triassic age from four different Peritethys basins in subequatorial latitudes. Similar distribution patterns of aluminum phosphate-sulfate (APS) minerals contents in these rocks in the four studied basins provide evidence of increased acidity during the Smithian-Spathian transition, coinciding with a lack of indicators of organic activity in the same interval. Thus, this period of high acidity on land, may have been one of the causes of this biological crisis. Based on the quantification of APS minerals in the studied sedimentary sequences, we propose that it was not until acidity in the environment diminished, that biotic recovery was possible. APS data may also be useful to interpret other past biotic crises.