RECORD OF END-PERMIAN AND EARLY TRIASSIC CRISIS FROM A HIGH-RESOLUTION SECTION IN EAST GREENLAND

The 252-Ma Permian-Triassic boundary (PTB) crisis, which decimated marine and terrestrial biotas and was associated with a major thermal event linked to elevated atmospheric CO₂ (Schneebeli-Hermann et al., 2013, Geology 41:579), has been extensively studied in low-latitude Tethyan sections but less so in high-latitude regions. In this study, we generated chemostratigraphic records for a composite section from Black Ridge West, Blue Elv, and Nasutdal in northeastern Greenland ranging from the late Changhsingian (Late Permian) Ravnefjeld Fm through the Griesbachian to mid-Dienerian (Early Triassic) Wordie Creek Fm. The entire succession was deposited in a rapidly subsiding marine rift basin that accumulated ~700 m of deltaic sediment in <1 million years, hence offering an unprecedented degree of resolution for chemostratigraphic studies. We generated major- and trace-element concentration data for >600 samples in this section, yielding a temporal resolution of <2000 years per sample. Our results document a major change in lithology at the end-Permian extinction horizon, marked by an increased flux of siliciclastics, a shift towards greater terrestrial chemical weathering intensity, the development of weakly reducing conditions, and possibly elevated marine productivity. These observations are consistent with an extreme warming event that commenced at the PTB and continued into the Early Triassic (Joachimski et al., 2012, Geology 40:195; Sun et al., 2012, Science 338:366; Romano et al., 2013, Nature Geoscience 6:57). The response of this high-latitude site to extreme Early Triassic warming thus differs in important respects from that of low-latitude Tethyan sites.