Late Campanian-Maastrichtian planktic foraminiferal biostratigraphy, taxonomy, and isotope paleoecology of ODP Leg 198 Sites 1209 and 1210, Shatsky Rise

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Author(s): Clark, Kendra R.
Source: Institution: University of Massachusetts at Amherst, Amherst, MA, United States
Note: In English. Master's thesis
Summary: Well-preserved and diverse assemblages of late Campanian-Maastrichtian age (76.5-65.5 Ma) planktic foraminifera from Ocean Drilling Program Sites 1209 and 1210 on Shatsky Rise provide an excellent source of data to better understand the environmental and biotic changes of the end-Cretaceous Period in the tropical Pacific. A thorough taxonomic and biostratigraphic study of planktic foraminifera has revealed significant differences in species ranges when compared to detailed studies from the western North Atlantic and eastern South Atlantic. These observations are attributed to site locations with different ocean current and productivity conditions. During the globally recognized "mid-Maastrichtian Event", inoceramid clams, rare at Shatsky Rise, dramatically increased (∼69.3 Ma) before suddenly going extinct (69.1 Ma). This Inoceramid Acme Event (IAE), occurs during high sedimentation rates (∼21.8-m/myr) and is indicated in planktic foraminifera by a 0.50 ppm positive shift in δ18O values (∼2°C cooling), a 0.24 ppm negative shift in δ13C values of and high species richness. A simultaneous decrease in both the δ18O and δ13C gradients between surface and thermocline dwelling planktic foraminifera indicate the IAE was possibly initiated by an increase in surface productivity due to the upwelling of cooler, nutrient-rich waters. A dissolution event was identified at ∼66.1 Ma lasting to the Cretaceous/Paleogene boundary (65.5 Ma) and is characterized by chalky, highly fragmented planktic foraminifera, increased dissolution of larger Globotruncanids, increased small (<63 µm) planktic foraminifera, large and increasingly abundant benthic foraminifera, a sharp decrease in species richness and increased sedimentation rates (∼19.9-m/myr). This event follows a transitional interval at ∼66.7 Ma where preservation is highly variable. The dissolution event, reported in previous studies at Shatsky Rise (Caron, 1975; Premoli Silva et al., 2005), is not reported in the North and South Atlantic but may help to explain the high diachroneity in species occurrences between ocean basins. These events may indicate that the calcite carbonate compensation depth (CCD) shoaled to shallower depths than previously reported (Theirstein, 1979) due to changing deep or intermediate water mass sources. Alternatively, the timing the dissolution is approximately coincident with the main pulse of Deccan Trap volcanism on the Indian subcontinent suggesting a possible link through ocean acidification.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Biostratigraphy; C-13/C-12; Campanian; Carbon; Cretaceous; Foraminifera; Globigerinacea; Globotruncanidae; Invertebrata; Isotope ratios; Isotopes; Leg 198; Maestrichtian; Mesozoic; Microfossils; North Pacific; Northwest Pacific; ODP Site 1209; ODP Site 1210; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleoecology; Protista; Rotaliina; Shatsky Rise; Stable isotopes; Taxonomy; Upper Campanian; Upper Cretaceous; West Pacific
Coordinates: N323900 N324000 E1583100 E1583000
N321300 N321300 E1581600 E1581600
Record ID: 2016038206
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