Citation:

odp.proc.sr.120.188.1992

Name: Chemobiostratigraphy of the Cretaceous/Paleocene boundary at ODP Hole 120-750A
Published: 1992
License: https://creativecommons.org/licenses/by/3.0/

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Abstract:

An integrated biostratigraphic and stable isotope investigation was conducted on a high-latitude sequence across the Cretaceous/Paleogene (K/P) boundary recovered in Hole 750A in the southern Indian Ocean. The sequence consists of nannofossil chalk and is discontinuous across the boundary; missing is an estimated 0.3-m.y. late Maestrichtian and early Danian interval. Nonetheless, because calcareous nannofossil Zones NP1 and NP2 are well-developed, micropaleontological studies of the sequence have yielded a detailed record of Danian high-latitude microplankton evolution. In addition, stable carbon isotope analyses of planktonic and benthic foraminifer and bulk samples provide a record of late Maestrichtian and early Danian surface- and deep-water carbon isotope variations. Together, the carbon isotope and carbonate accumulation records serve as an index of regional marine net productivity across the boundary.

Earliest Danian nannoplankton assemblages consisted mainly of persistent genera that were generally rare or absent in the Upper Cretaceous at Hole 750A. However, by 0.5-0.6 m.y. after the boundary, newly evolving Danian taxa became dominant. The turnover in nannofossil assemblages was accompanied by significant changes in rates of net productivity as gauged by carbon isotope distributions and carbonate accumulation rates. During the period dominated by persistent taxa, net productivity was extremely low, as reflected by the absence of vertical delta13C gradients and reduced carbonate accumulation rates. Later in the Danian, as new species evolved and flourished, vertical delta13C gradients reappeared and carbonate accumulation rates increased, signaling partial recovery of net productivity in this region. The absolute timing and magnitude of late Maestrichtian and early Danian biotic and geochemical changes in the southern Indian Ocean were similar to those recorded in other pelagic K/P boundary sequences from low- and mid-latitude Atlantic and Pacific sites, indicating that these events were ubiquitous.

Project(s):

Ocean Drilling Program (ODP)

Coverage:

Latitude: -57.592000 * Longitude: 81.240300

Date/Time Start: 1988-04-14T06:15:00 * Date/Time End: 1988-04-18T14:00:00

Event(s):

120-750A * Latitude: -57.592000 * Longitude: 81.240300 * Date/Time Start: 1988-04-14T06:15:00 * Date/Time End: 1988-04-18T14:00:00 * Elevation: -2041.0 m * Penetration: 460.5 m * Recovery: 68.63 m * Location: South Indian Ridge, South Indian Ocean * Campaign: * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 21 core; 189.3 m cored; 0 m drilled; 36.3 % recovery

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

4 datasets

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Datasets listed in this publication series

Zachos, JC; Aubry, M-P; Berggren, WA et al. (1992): (Table 1) Carbonate concentration of whole-rock samples from ODP Hole 120-750A. https://doi.org/10.1594/PANGAEA.728902
Zachos, JC; Aubry, M-P; Berggren, WA et al. (1992): (Table 3) Stable isotope ratios of foraminifera and bulk carbonate from ODP Hole 120-750A. https://doi.org/10.1594/PANGAEA.728909
Zachos, JC; Aubry, M-P; Berggren, WA et al. (1992): (Table 2) Abundances of nannofossils in the lower Danian of ODP Hole 120-750A. https://doi.org/10.1594/PANGAEA.728905
Zachos, JC; Aubry, M-P; Berggren, WA et al. (1992): (Figure 6) Range chart of planktonic foraminifers across the K/T boundary at ODP Hole 120-750A. https://doi.org/10.1594/PANGAEA.728914