Marine anoxia and delayed Earth system recovery after the end-Permian extinction


Lau K. V., Maher K., ALTINER D., Kelley B. M., Kump L. R., Lehrmann D. J., ...Daha Fazla

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, cilt.113, sa.9, ss.2360-2365, 2016 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 113 Sayı: 9
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1073/pnas.1515080113
  • Dergi Adı: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.2360-2365
  • Anahtar Kelimeler: paleoredox, uranium isotopes, biogeochemical cycling, carbon isotopes, Early Triassic, URANIUM ISOTOPE FRACTIONATION, TRIASSIC BOUNDARY, MASS EXTINCTION, BIOTIC RECOVERY, OCEANIC ANOXIA, SOUTH CHINA, GREAT BANK, NANPANJIANG BASIN, GUIZHOU PROVINCE, REDOX CONDITIONS
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Delayed Earth system recovery following the end-Permian mass extinction is often attributed to severe ocean anoxia. However, the extent and duration of Early Triassic anoxia remains poorly constrained. Here we use paired records of uranium concentrations ([U]) and U-238/U-235 isotopic compositions (delta U-238) of Upper Permian- Upper Triassic marine limestones from China and Turkey to quantify variations in global seafloor redox conditions. We observe abrupt decreases in [U] and delta U-238 across the end-Permian extinction horizon, from similar to 3 ppm and -0.15 parts per thousand to similar to 0.3 ppm and -0.77%, followed by a gradual return to preextinction values over the subsequent 5 million years. These trends imply a factor of 100 increase in the extent of seafloor anoxia and suggest the presence of a shallow oxygen minimum zone (OMZ) that inhibited the recovery of benthic animal diversity and marine ecosystem function. We hypothesize that in the Early Triassic oceans-characterized by prolonged shallow anoxia that may have impinged onto continental shelves-global biogeochemical cycles and marine ecosystem structure became more sensitive to variation in the position of the OMZ. Under this hypothesis, the Middle Triassic decline in bottom water anoxia, stabilization of biogeochemical cycles, and diversification of marine animals together reflect the development of a deeper and less extensive OMZ, which regulated Earth system recovery following the end-Permian catastrophe.