Late Triassic mollusk-dominated hydrocarbon-seep deposits from TurkeyShow others and affiliations
2017 (English)In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 44, p. 751-754Article in journal (Refereed) Published
Abstract [en]
Deep-sea hydrothermal vents and hydrocarbon seeps host unique ecosystems relying on geochemical energy rather than photosynthesis. Whereas the fossil and evolutionary history of these ecosystems is increasingly well known from the Cretaceous onward, their earlier history remains poorly understood and brachiopods are considered to have played a dominant role during the Paleozoic and Mesozoic. Here we report five new hydrocarbon-seep deposits from the Upper Triassic Kasımlar shales in southern Turkey. The pyritiferous seep limestones predominantly consist of 13C-depleted micrite with δ13C values as low as −10.4‰, and contain only sparse 13C-depleted rim cement (δ13C as low as −12.0‰), interpreted to result from the recrystallization of banded and botryoidal crystal aggregates of fibrous cement. The geologic ages of the studied seep deposits were determined as late Carnian and early Norian using conodonts. The associated fauna is dominated by modiomorphid and anomalodesmatan bivalves, and also includes a diversity of gastropods and the dimerelloid brachiopod Halorella. These faunal assemblages allow a comparison between seep faunas from the two major Triassic ocean basins—the present assemblages being from Tethys, and the only previously known examples being from eastern Panthalassa—and indicate that a cosmopolitan, seep-restricted fauna as in the present-day oceans has existed since the Late Triassic. With almost 20 species, the seep fauna of the Kasımlar shales approaches the diversity of Cretaceous to present-day seep faunas, further emphasizing the ecological similarity of seep faunas since the early Mesozoic. Our findings also highlight that brachiopods and bivalves had a more complex history of coexistence at seeps than currently appreciated.
Place, publisher, year, edition, pages
Boulder: Geological Society of America, 2017. Vol. 44, p. 751-754
Keywords [en]
Asia, Gastropoda, geochemistry, aragonite, Brachiopoda, carbonate rocks, oxygen, Middle East, O-18/O-16, Mollusca, Taurus Mountains, sulfides, carbon, carbonates, C-13/C-12, Bivalvia, calcite, Triassic, Turkey, Invertebrata, isotope ratios, isotopes, limestone, Mesozoic, paleoecology, sedimentary rocks, Upper Triassic, pyrite, stable isotopes
National Category
Other Earth Sciences
Research subject
Ecosystems and species history
Identifiers
URN: urn:nbn:se:nrm:diva-2505DOI: 10.1130/G39259.1OAI: oai:DiVA.org:nrm-2505DiVA, id: diva2:1156232
Note
Financial support was provided by the Fonds zur Förderung der wissenschaftlichen Forschung through grant M1779-N29 to Kiel and Peckmann
2017-11-102017-11-102025-02-07Bibliographically approved