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Stable carbon‐isotope record of shallow‐marine evaporative epicratonic basin carbonates, Ordovician Williston Basin, North America
Author(s) -
Husinec Antun,
Bergström Stig M.
Publication year - 2015
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/sed.12152
Subject(s) - geology , conodont , ordovician , paleontology , isotopes of carbon , diagenesis , biostratigraphy , evaporite , carbonate , chemostratigraphy , facies , structural basin , geochemistry , total organic carbon , ecology , materials science , metallurgy , biology
Secular variations in stable carbon‐isotope values of marine carbonates are used widely to correlate successions that lack high‐resolution index fossils. Various environmental processes, however, commonly may affect and alter the primary marine carbon‐isotope signal in shallow epicratonic basins. This study focuses on the marine carbon‐isotope record from the carbonate–evaporite succession of the upper Katian (Upper Ordovician) Red River Formation of the shallow epicratonic Williston Basin, USA . It documents the carbon‐isotope signal between the two major Ordovician positive shifts in δ 13 C, the early Katian Guttenberg and the Hirnantian excursions. Eight δ 13 C stages are identified based on positive excursions, shifts from positive to negative values and relatively uniform δ 13 C carb values. A correlation between carbon‐isotope trends and the relative sea‐level changes based on gross facies stacking patterns shows no clear relation. Based on the available biostratigraphy and δ 13 C trends, the studied Williston Basin curves are tied to the isotope curves from the North American Midcontinent, Québec (Anticosti Island) and Estonia, which confirm the Late Katian age ( Aphelognathus divergens Conodont Zone) of the upper Red River Formation. The differences in the δ 13 C overall trend and absolute values, coupled with the petrographic and cathodoluminescence evidence, suggest that the carbon‐isotope record has been affected by the syndepositional environmental processes in the shallow and periodically isolated Williston Basin, and stabilized by later burial diagenesis under reducing conditions and the presence of isotopically more negative fluids.