MAJOR, MINOR, AND TRACE ELEMENT ANALYSIS OF THE MONTNEY FORMATION, PEACE RIVER EMBAYMENT (EASTERN ALBERTA, CANADA) FOLLOWING THE PERMIAN-TRIASSIC MASS EXTINCTION

The Permian-Triassic mass extinction led to an estimated loss of about 88 to 96% of all marine species, and also led to heavy losses to many terrestrial vertebrate families as well. Life eventually recovered by the Middle Triassic, although recovery was complex for ocean life and dependent on environmental conditions. Examination of a drill core (14-17-74-10W6) through Lower Triassic sedimentary rocks from the Peace River basin of eastern Alberta, Canada allows the reconstruction of paleoenvironmental conditions during the middle Early Triassic (Dienerian to Smithian). The Dienerian to Smithian-aged rocks consists of 4 distinct sequences, with the lowermost sequence (D6 – uppermost Dienerian) consisting of laminated black shale with some fish debris, S0 (lowermost Smithian) made up of laminated black to grayish colored siltstone, S1 consisting of laminated phosphatic black shale, and S3 made up of mottled to faintly laminated, very fine sandstone and siltstone. The sedimentology of the unit provides strong evidence for a widespread anoxic event that persisted across the Dienerian and Smithian, which will be examined in detail using trace elemental data, including Ba, Cu, Ni, and Zn to determine paleoproductivity and Mo and V to examine whether ocean waters were oxic, anoxic, or euxinic. If results demonstrate high primary productivity and low benthic oxygenation, then they will provide evidence for productivity-driven anoxia and support the hypothesis of Algeo and Twitchett (2010) that denudation of the continents and enhanced weathering rates drove anoxic conditions in marginal marine environments. If productivity indicators imply low or dampened rates of primary productivity, then this will suggest that anoxic conditions in the region were due to the influence of a deep, anoxic water mass in eastern Panthalassa, and support the hypothesis of Isozaki (1997) that much of Panthalassa was anoxic from the Upper Permian to the Middle Triassic. Overall, the results of this study should shed light not only the role of environmental conditions, specifically anoxia, in determining the timing and shape of recovery from the Permian-Triassic mass extinction, but also the drivers of those conditions.