Seismic stratigraphy of the Shatsky Rise sediment cap and implications for pelagic sedimentation on oceanic rises

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Author(s): Sager, W. W.; Clark, R. W.; Weil, A. B.
Author Affiliation(s): Primary:
University of Houston, Department of Earth and Atmospheric Sciences, Houston, TX, United States
Bryn Mawr College, Bryn Mawr, PA, United States
Volume Title: AGU 2016 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2016; American Geophysical Union 2016 fall meeting, San Francisco, CA, Dec. 12-16, 2016. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Shatsky Rise, an oceanic plateau in the northwest Pacific, contains several basement highs (Tamu, Ori, and Shirshov massifs), each capped with an expanded record of pelagic sedimentation since the early Cretaceous. A common view is that these layers reflect basin-wide oceanographic conditions, including such major events as Cretaceous ocean anoxia and the Paleocene-Eocene Thermal Maximum. In previous years, the seismic stratigraphy for the Shatsky Rise sediment cap has been interpreted from DSDP and ODP drilling data and low-quality seismic reflection profiles from several cruises. These studies focused primarily on the southern summit of Tamu Massif and concluded that sedimentation was continuous except during major oceanographic events resulting in hiatuses across Shatsky Rise (e.g. increased circulation or shoaling of the carbonate compensation depth). The accepted stratigraphic model, based on data from Tamu Massif, includes five major layers punctuated by four unconformities. Recent, high-quality seismic reflection data and additional drilling allow us to revisit this model. The data reveal that deposition was more heterogeneous than previously thought. While all three sediment caps appear to have similar depositional histories, the records of each massif also display local variability. Both Ori and Shirshov have unique stratigraphic sequences that deviate from the five-part model of Tamu Massif. At a finer scale, each sediment cap exhibits significant internal complexities within seismic units, in contrast to the expected uniform deposition. The stratigraphic model determined in one part of the sediment cap cannot be confidently applied to the rest of the massif (or to adjacent massifs) without additional evidence to aid correlations. Our study suggests that factors such as variable currents flowing over the plateau topography contributed to significant lateral variability of the sedimentation atop Shatsky Rise.
Year of Publication: 2016
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Cenozoic; Deep Sea Drilling Project; North Pacific; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; Paleocene-Eocene Thermal Maximum; Paleogene; Shatsky Rise; Tertiary; West Pacific
Record ID: 2018001683
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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