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The oxygen and carbon isotope composition of Carboniferous fossil components: sea‐water effects
Author(s) -
BRAND UWE
Publication year - 1982
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/j.1365-3091.1982.tb01715.x
Subject(s) - geology , calcite , carboniferous , diagenesis , meteoric water , pennsylvanian , carbonate , isotopes of oxygen , seawater , isotopes of carbon , paleontology , carbon fibers , oceanography , geochemistry , total organic carbon , environmental chemistry , chemistry , organic chemistry , structural basin , hydrothermal circulation , materials science , composite number , composite material
The aragonitic molluscs and lime‐mud of the Pennsylvanian Buckhorn asphalt (Deese Group) of southern Oklahoma precipitated calcium carbonate in oxygen and carbon isotopic equilibrium with ambient sea‐water. In addition, δ 18 O values indicate that the pelecypods precipitated their shells during the warmer months of the year. The coiled nautiloids probably precipitated their shells in the warm surface water and throughout the year. For the orthocone nautiloids, the δ 18 O values suggest that they precipitated their shells in deeper/cooler water. The low‐Mg calcite brachiopods of the Mississippian Lake Valley Formation of New Mexico precipitated shells in oxygen and carbon isotopic equilibrium with ambient sea‐water. The δ 18 O and δ 13 C values of the Buckhorn and Lake Valley faunas, in conjunction with other published results, suggest that Carboniferous sea‐water was, on a average, depleted in δ 18 O by 1·5 ± 2‰, PDB, relative to Recent sea‐water. However, the δ 13 C value of +2.6 ± 2‰, PDB, for average Carboniferous sea‐water is similar to that of Recent ocean water. Early diagenetic alteration of metastable carbonates probably occurs in a meteoric‐sea‐water mixing zone. In this zone the oxygen and carbon isotopic compositions of these components are increased by about 2‐4‰, PDB over their marine composition.