Discovery and paleoceanographic significance of unconsolidated Cretaceous pelagic sediment cover on northern Tamu Massif, Shatsky Rise (IODP Site U1348)

Author(s): Ando, A.; Littler, Kate; Woodard, S. C.; Herrmann, Sandra; Evans, Helen F.; Khim, B.; Robinson, Stuart A.; Huber, B. T.
Author Affiliation(s): Primary:
Smithsonian Institution, Washington, DC, United States
University College London, United Kingdom
Texas A&M University, United States
Eidgenössische Technische Hochshcule Zürich, Switzerland
Lamont-Doherty Earth Observatory, United States
Pusan National University, South Korea
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: IODP Expedition 324 to Shatsky Rise was primarily aimed at recovering the igneous basement rocks, thereby visiting the summit and steep-gradient flank sites overlain by thin sediment cover. Together with the use of rotary core barrel drilling, this expedition was deemed to be unsuitable for paleoceanographic study of sediments/sedimentary rocks. Fortunately, an intriguing suite of Cretaceous pelagic carbonate sediments was recovered from the ∼80 m-thick interval of Site U1348 on the northern summit of Tamu Massif (Southern High), albeit poor in core recovery and dominated by cherts at some intervals. Available carbonate materials were remarkably unconsolidated, and its softness warranted the sedimentological description as "ooze," meaning that the sediments escaped the normal diagenetic processes since their deposition. Highlights were the recoveries of the oldest known calcareous ooze of early Aptian age (recovered as 22 cm-thick interval in Core 10) and the freshest pelagic sedimentary record of the Santonian-Campanian transition (1.4 m-thick in Core 2). Detailed shore-based studies of calcareous microfossils, isotopic geochemistry (C, O and Sr isotopes), and/or magnetic reversals strengthen the above Cores 2 and 10 shipboard chronology and allow new insights to be presented for Cretaceous paleoceanography. Specifically, new stable isotope data from bulk carbonates and/or individual benthic foraminiferal separates enable us to extend the reliable oxygen isotope record of benthic foraminifera to 120 Ma and to document a hitherto unknown major cooling event around the Santonian-Campanian transition. These new findings also have significant bearing on the future direction of scientific deep-sea drilling. Namely, although Cretaceous pelagic sedimentary records in the central Pacific have been notoriously incomplete due largely to significant burial diagenesis of carbonates as well as silicification, pristine calcareous materials are still anticipated to be present at the summits of seamounts. Such a setting, at least northern Tamu Massif, will be an important target in future paleoceanographic expedition.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; 18 Geophysics, Solid-Earth; Aptian; Basement; Calcic composition; Carbonate rocks; Cretaceous; Crust; Expedition 324; IODP Site U1348; Integrated Ocean Drilling Program; Lower Cretaceous; Mesozoic; North Pacific; Northwest Pacific; Oceanic crust; Pacific Ocean; Paleo-oceanography; Santonian; Sedimentary rocks; Shatsky Rise; Tamu Massif; Upper Cretaceous; West Pacific
Record ID: 2017006591
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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