The mid-Maastrichtian event on Shatsky Rise, ODP Leg 198

Author(s): Clark, Kendra R.; Leckie, R. Mark; Burns, Stephen J.; Dameron, Serena; Frank, Tracy D.
Author Affiliation(s): Primary:
University of Massachusetts, Department of Geosciences, Amherst, MA, United States
University of Nebraska, United States
Volume Title: Geological Society of America, 2010 annual meeting
Source: Abstracts with Programs - Geological Society of America, 42(5), p.298; Geological Society of America, 2010 annual meeting, Denver, CO, Oct. 31-Nov. 3, 2010. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: ODP tropical Pacific sites 1209 and 1210 provide an unusual record of the mid-Maastrichtian Event (MME). Clusters of large Inoceramus prisms are restricted to several meters of section before abruptly disappearing. The significance of the short range of inoceramid bivalves over the shallowest sites of Shatsky Rise is currently not understood. New isotopic and benthic foraminiferal population data from these sites may provide a possible explanation to the limited stratigraphic range of inoceramids on Shatsky Rise. We suggest that this was a regional expression of a diachronous event. This study shows the MME is indicated in surface-dwelling planktic foraminifera by a 0.50ppm positive shift in δ18O values (∼2 °C cooling) and a 0.24ppm negative shift in δ13C values occurring at ∼69.3 Ma. This is coincident with the FO of inoceramids and changes in benthic foraminiferal populations. This cooling event is in contrast to a previous study of these sites by Frank et al. (2005; Paleoceanography) which showed a negative shift in surface δ18O values at the MME. Increased seasonality could account for differences in surface temperatures as recorded by two different species P. costulata (this study) and R. rugosa (Frank et al.) and may indicate a preference for cooler water and warmer water, respectively. Simultaneous is a collapse of both the δ18O and δ13C gradient between surface (P. costulata) and thermocline (G. stuartiformis) dwellers. The collapse of the surface δ13C gradient records higher productivity due to the upwelling of cooler, nutrient-rich (12C-rich) waters. There are no significant shifts in the δ18O and δ13C values of planktic foraminifera at the time inoceramids abruptly disappear from the record at Shatsky Rise. After this time the δ13C and δ18O gradient in the surface waters stayed high but variable before a sudden warming event in the planktic record at 68.7 Ma a date which is in good agreement for the global extinction of inoceramid bivalves in the North Pacific (Nifuku et al., 2009; Palaeo3). This supports our hypothesis that the short range of inoceramid bivalves at Shatsky Rise was a regional event brought on by changes in surface productivity and greater flux of food out of the surface waters, or by a change in deep waters.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Bivalvia; C-13/C-12; Carbon; Cretaceous; Extinction; Foraminifera; Inocerami; Inoceramidae; Inoceramus; Invertebrata; Isotope ratios; Isotopes; Leg 198; Maestrichtian; Mesozoic; Microfossils; Middle Maestrichtian; Mollusca; North Pacific; Northwest Pacific; Nutrients; O-18/O-16; ODP Site 1209; ODP Site 1210; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Planktonic taxa; Productivity; Protista; Pteriina; Pterioida; Senonian; Shatsky Rise; Stable isotopes; Thermocline; Upper Cretaceous; Upwelling; West Pacific
Coordinates: N323900 N324000 E1583100 E1583000
N321300 N321300 E1581600 E1581600
Record ID: 2011086969
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States