| Title | Carnian-Norian (Late Triassic) climate change: evidence from conodont oxygen isotope thermometry with implications for reef development and Wrangellian tectonics |
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| Author | Sun, Y D ;
Orchard, M J; Kocsis, Á T; Joachimski, M M |
| Source | Earth and Planetary Science Letters vol. 534, 116082, 2020 p. 1-14, https://doi.org/10.1016/j.epsl.2020.116082 |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200181 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | British Columbia |
| NTS | 93O/13; 93O/14; 93O/15; 93O/16; 94B/01; 94B/02; 94B/03; 94B/04; 94B/05; 94B/06; 94B/07; 94B/08; 103K/02; 103K/03 |
| Area | Williston Lake; Peace Reach; Haida Gwaii; Frederick Island; Black Bear Ridge |
| Lat/Long WENS | -124.0000 -122.0000 56.5000 55.7500 |
| Lat/Long WENS | -133.1667 -132.8333 55.3333 54.1667 |
| Subjects | Nature and Environment; paleontology; geochemistry; Science and Technology; Upper Triassic; Carnian; Norian; paleoclimatology; paleotemperatures; thermal history; paleoenvironment; oceanography; reefs;
biostratigraphy; micropaleontology; microfossils; conodonts; isotopic studies; oxygen isotopes; ecology; environmental impacts; microfaunal assemblages; fossil zones; Canadian Cordillera; Insular Belt; Wrangelia Terrane; Climate change; Phanerozoic;
Mesozoic; Triassic |
| Illustrations | location maps; logs; tables; figures; plots; schematic models |
| Released | 2020 01 21 |
| Abstract | The Carnian-Norian (C-N) transition (Late Triassic) has long been postulated as an interval of major climatic changes, though the nature of such changes and their ecological impact remains largely
unexplored. We use oxygen isotopes measured on monogeneric conodont assemblages (delta O-18(pO4)) from the Canadian Cordillera to trace seawater temperature evolution at the western margin of Pangea and in the allochthonous Wrangellia Terrane.
Different conodont taxa show conspicuous offsets in delta O-18(pO4), suggesting that they had preferential habitat depths and genus-specific temperature corrections must be applied. Thus, delta O-18(pO4) from the Williston Lake sections indicates low
mid-latitude sea surface temperatures (SSTs) ranging from similar to 28 to 35 degrees C, favouring a generally warm Late Triassic climate scenario. The parvus Subzone of C-N transition, which marks the peak faunal turnover, records major climatic
perturbations: SSTs peaking at similar to 34 degrees C then decreasing to similar to 29 degrees C. This is followed by a quick temperature rebound and a second pulse of cooling from 33 to 27 degrees C in the asymmetrica Norigondolella Subzone,
marking the coldest temperatures in the similar to 20 Myr study interval. A secular warming trend towards the late Norian reinstated after the transient cooling in the earliest Norian, coinciding with reef expansions in the Late Triassic. The
middle-late Norian (Alaunian 3-Sevatian 1) represents a hothouse climate comparable to the Paleocene-Eocene Thermal Maximum and its warmth supressed both diversity and origination rates of reef-building biota. Early Norian delta O-18(pO4) data from
Frederick Island, Haida Gwaii (part of the Wrangellia Terrane) are more depleted in O-18 compared to coeval samples from the Black Bear Ridge, indicating similar to 3-5 degrees C warmer temperatures than the Laurentian epicontinental sea. The
temperature difference supports a more southern, probably sub-equatorial position for at least part of the Wrangellia Terrane during the earliest Norian. |
| GEOSCAN ID | 326593 |
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