Publication Date:
2024-01-09
Description:
Ocean anoxic events were periods of high carbon burial that led to drawdown of atmospheric carbon dioxide, lowering of bottom-water oxygen concentrations and, in many cases, significant biological extinction (Arthur et al., 1990; Erbacher et al., 1996, doi:10.1130/0091-7613(1996)024〈0499:EPORAO〉2.3.CO;2; Kuypers et al., 1999, doi:10.1038/20659; Jenkyns, 1997; Hochuli et al., 1999, doi:10.1130/0091-7613(1999)027〈0657:EOHPAC〉2.3.CO;2). Most ocean anoxic events are thought to be caused by high productivity and export of carbon from surface waters which is then preserved in organic-rich sediments, known as black shales. But the factors that triggered some of these events remain uncertain. Here we present stable isotope data from a mid-Cretaceous ocean anoxic event that occurred 112 Myr ago, and that point to increased thermohaline stratification as the probable cause. Ocean anoxic event 1b is associated with an increase in surface-water temperatures and runoff that led to decreased bottom-water formation and elevated carbon burial in the restricted basins of the western Tethys and North Atlantic. This event is in many ways similar to that which led to the more recent Plio-Pleistocene Mediterranean sapropels, but the greater geographical extent and longer duration (~46 kyr) of ocean anoxic event 1b suggest that processes leading to such ocean anoxic events in the North Atlantic and western Tethys were able to act over a much larger region, and sequester far more carbon, than any of the Quaternary sapropels.
Keywords:
171-1049C; Blake Nose, North Atlantic Ocean; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Gyroidinoides nitidus, δ13C; Gyroidinoides nitidus, δ13C, standard deviation; Gyroidinoides nitidus, δ18O; Gyroidinoides nitidus, δ18O, standard deviation; Hedbergella aff. trocoidea, δ13C; Hedbergella aff. trocoidea, δ13C, standard deviation; Hedbergella aff. trocoidea, δ18O; Hedbergella aff. trocoidea, δ18O, standard deviation; Hedbergella speetonensis, δ13C; Hedbergella speetonensis, δ13C, standard deviation; Hedbergella speetonensis, δ18O; Hedbergella speetonensis, δ18O, standard deviation; Isotope ratio mass spectrometry; Joides Resolution; Leg171B; Ocean Drilling Program; ODP; Osangularia schloenbachi, δ13C; Osangularia schloenbachi, δ13C, standard deviation; Osangularia schloenbachi, δ18O; Osangularia schloenbachi, δ18O, standard deviation; Sample code/label
Type:
Dataset
Format:
text/tab-separated-values, 398 data points
Permalink
