Stratigraphy of the Cretaceous-Paleogene transition interval at the Lord Howe Rise, southern Pacific

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http://abstractsearch.agu.org/meetings/2018/FM/PP41D-1879.html
Author(s): Kuroda, J.; Saito, S.; Usui, Y.; Hagino, K.; Bown, P. R.; Hsiung, K. H.; Sakai, S.; Hackney, R. I.; Ohkouchi, N.
Author Affiliation(s): Primary:
University of Tokyo, Atmosphere and Ocean Research Institute, Kashiwa, Japan
Other:
Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
Kochi University, Kochi, Japan
University College London, London, United Kingdom
Geoscience Australia, Canberra, A.C.T., Australia
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: During Deep Sea Drilling Project (DSDP) Leg 21, Cenozoic and latest Cretaceous pelagic sediments were recovered at Site 208 on the Lord Howe Rise, southwestern Pacific. We provide new geochemical, biostratigraphic and magnetostratigraphic data for cores from Site 208 to constrain stratigraphy around the Cretaceous/Paleogene boundary (K-Pg). The sediment is mainly composed of calcareous chalk interbedded with silicified mudstone and chert. Paleomagnetic polarity and calcareous nannofossil assemblages indicate that the Maastrichtian and Danian chalk between 550 and 590 meters below seafloor (mbsf) was deposited with an average sedimentation rate of 5-7 mm per thousand years. The sedimentation rate significantly decreased in an interval of silicified mudstone and chalk around 576-577 mbsf, which spans the transition between Maastrichtian and Danian. Variations in osmium isotopic composition (187Os/188Os) can be used for stratigraphic correlation, as the K-Pg boundary marks a low 187Os/188Os value of ≈0.15 compared to the Maastrichtian (≈0.5-0.6) and Danian (≈0.4). Our 187Os/188Os data indicate a similar variation with that of coeval ocean water, with a lowest 187Os/188Os value of ≈0.16 in a silicified mudstone sample at 576.8 mbsf. This suggests that the silicified mudstone represents the K-Pg boundary. Detail investigation on calcareous nannofossil assemblages is also consistent with the Os isotopic data. Our stratigraphic investigation has reveals that while the K-Pg boundary interval at Site 208 may not be as continuous as those preserved at Shatsky Rise, Maud Rise and Walvis Ridge, it nevertheless captures a time interval that is close to the asteroid impact.
Year of Publication: 2018
Research Program: DSDP Deep Sea Drilling Project
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Cretaceous; DSDP Site 208; Deep Sea Drilling Project; Leg 21; Lithostratigraphy; Lord Howe Rise; Mesozoic; Pacific Ocean; Paleogene; South Pacific; Southwest Pacific; Stratigraphic boundary; Tertiary; West Pacific
Coordinates: S260637 S260636 E1611317 E1611316
Record ID: 2019063642
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