Wednesday, June 19, 2013

Highlights—Post-Extinction Recovery: Hindered by Acid Flashbacks

Extinction events mark crises in the history of life, and recovery from these events commonly is protracted.  To better understand the timing, nature, and controls of post-Permian biotic recovery, Galán-Abellán et al. document petrography, whole-rock geochemistry, and isotopic analyses of early diagenetic aluminium-phosphate-sulphate (APS) minerals in Early-Middle Triassic continental sandstones in the Iberian Ranges (Iberian Peninsula).  Sr and S isotopes indicate mixed sources for these elements, derived from the dissolution of pre-existing detrital minerals (phosphates, K-feldspar, clay minerals and pyrite) and from marine and volcanic aerosols. The formation of APS minerals is interpreted to be related to acid meteoric waters, which in turn reflect arid, acidic conditions unfavorable to biotic recovery after the Permian–Triassic biotic crisis.  The study suggests that analysis of APS minerals and Sr and S isotopes, coupled with sedimentologic and stratigraphic analysis, can provide enhanced means to assess on paleoenvironmental change and biotic recovery.

Sources of Sr and S inaluminum-phosphate–sulfate minerals in Early–Middle Triassic sandstones(Iberian Ranges, Spain) and paleoenvironmental implications for the west Tethys by Belén Galán-Abellán, Jacinto Alonso-Azcárate, Robert J. Newton, Simon H. Bottrell, José F. Barrenechea, M. Isabel Benito, Raúl De la Horra, José López-Gómez, and Javier Luque

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