Stable Isotope and Trace Element Geochemistry of Carbonate Sediments across the Cretaceous/Tertiary Boundary at Deep Sea Drilling Project Hole 577, Leg 86

Abstract

Detailed analyses of well-preserved carbonate samples from across the Cretaceous/Tertiary boundary in Hole 577 have revealed a significant decline in the δ 13 C values of calcareous nannoplankton from the Maestrichtian to the Danian Age accompanied by a substantial reduction in carbonate accumulation rates. Benthic foraminifers, however, do not exhibit a shift in carbon composition similar to that recorded by the calcareous nannoplankton, but actually increase slightly over the same time interval. These results are similar to the earlier findings at two North Pacific Deep Sea Drilling Project locations, Sites 47.2 and 465, and are considered to represent a dramatic decrease in oceanic phytoplankton production associated with the catastrophic Cretaceous/Tertiary boundary extinctions. In addition, the change in carbon composition of calcareous nannoplankton across the Cretaceous/Tertiary boundary at Hole 577 is accompanied by only minor changes in the oxygen isotope trends of both calcareous nannoplankton and benthic foraminifers, suggesting that temperature variations in the North Pacific from the late Maestrichtian to the early Danian Age were insignificant.

Global change at the Paleocene-Eocene boundary: climatic and evolutionary consequences of tectonic events

“…(Zachos et al, 1989) Site *, Benthics (Zacho~ et al, 1989;Miller et al, 1987) 577 "'"tr'--FF & Bulk (Zachos et al, 1985;Shackletun et al, 1985) 8 13C ( Site -----o--Bulk (Shackleton & Hall, 1984) 528 . Benthics (Shackleton et al, 1984) Fig extinction event near the end of the Paleocene.…”

“…In addition to the opening and closing of oceanic gateways, which effect global transport paths of heat and moisture, the chemistry, especially the CO2 content, of oceans and atmospheres changes on tectonic timescales in response to sea-floor hydrothermal activity (Berner et al, 1983) and to volcanism (Arthur et al, 1985). Both hydrothermal activity (Owen and Rea, 1985;Rea and Leinen, 1986;Lyle et al, 1987;Olivarez and Owen, 1989) and volcanism (Rea and Vallier, 1983;White and McKenzie, 1989) are much more intense during times of continental rifting and oceanic plate boundary rearrangements; the geochemical consequences of these tectonic events, which include the CO 2 budget (Owen and Rea, 1985), may even be reflected in the biosphere (Rich et al, 1986).…”

Uppermost Cretaceous to middle Oligocene carbon and oxygen isotope stratigraphy of Southwest Pacific: Holes 1121B and 1124C, ODP Leg 181

“…We interpret that a small hiatus exists somewhere in the interval between 461.68 and 462.81 mbsf, spanning a missing period of 61-64.8 m.y. Zachos et al (1985) and Shackleton et al (1985). A total of six chemostratigraphic correlation lines are assigned.…”

“…2, 3). After establishing the general chronological scheme, we correlated the Paleocene carbon isotope profiles of the two studied sites with that of DSDP 577 generated from bulk sediments (Shackleton et al 1985;Zachos et al 1985) for a more detailed calibration.…”

“…4). The δ 13 C records of bulk carbonates were compiled by stacking measurements reported by Shackleton et al (1985) and Zachos et al (1985) (Fig. 5).…”