- journal_title：Geology
- Contributor：Mark A. Sephton ; Ken Amor ; Ian A. Franchi ; Paul B. Wignall ; Robert Newton ; John-Paul Zonneveld
- Publisher：Geological Society of America
- Date：2002-
- Format：text/html
- Language：en
- Identifier：10.1130/0091-7613(2002)030<1119:CANIDA>2.0.CO;2
- journal_abbrev：Geology
- issn：0091-7613
- volume：30
- issue：12
- firstpage：1119
Major perturbations of organic carbon and nitrogen isotope ratios from a Norian-Rhaetian (Late Triassic) boundary section in British Columbia coincide with an extinction of the dominant, deep-water invertebrate fauna of the Late Triassic (monotids and most ammonoids). The carbon isotope excursion is attributed to the development of widespread oceanic stagnation that favored organic-rich shale deposition. The coincident nitrogen isotope excursion suggests that progressively more nitrate-limited productivity forced a change to nitrogen-fixing cyanobacteria populations as ocean stagnation created nutrient-starved conditions. The biotic crisis and geochemical events of the Norian-Rhaetian boundary predate the latest Rhaetian (end-Triassic) mass extinction. Thus, the Late Triassic interval was marked by more than one extinction event.