The Triassic-Jurassic boundary is generally considered as one of the
major extinctions in the history of Phanerozoic. The high-resolution
ammonite correlations and carbon isotope marine record in the New York
Canyon area allow to distinguish two negative carbon excursions across
this boundary with different paleoenvironmental meanings. The Late
Rhaetian negative excursion is related to the extinction and regressive
phase.
The Early Hettangian delta(13)C(org) negative excursion is associated
with a major floristic turnover and major ammonite and radiolarian
radiation. The end-Triassic extinction-Early Jurassic recovery is fully
compatible with a volcanism-triggered crisis, probably related to the
Central Atlantic Magmatic Province. The main environmental stress might
have been generated by repeated release of SO(2) gas, heavy metals
emissions, darkening, and subsequent cooling. This phase was followed by
a major long-term CO(2) accumulation during the Early Hettangian with
development of nutrient-rich marine waters favouring the recovery of
productivity and deposition of black shales. (C) 2004 Elsevier B.V. All
rights reserved.