Attempts to model the Lower Cretaceous pelagic sedimentary cover of Shatsky Rise (NW Pacific Ocean) from downhole geophysical records

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doi: 10.1016/j.sedgeo.2008.08.007
Author(s): Robinson, Stuart A.; Williams, Trevor
Author Affiliation(s): Primary:
University College London, Department of Earth Sciences, London, United Kingdom
Other:
Lamont-Doherty Earth Observatory, United States
Volume Title: Sedimentary Geology
Source: Sedimentary Geology, 212(1-4), p.1-11. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0037-0738 CODEN: SEGEBX
Note: In English. Based on Publisher-supplied data; illus., incl. 2 tables, geol. sketch map
Summary: Ocean Drilling Program (ODP) Leg 198 to Shatsky Rise cored Lower Cretaceous sediments at three sites (Sites 1207, 1213, and 1214). Unfortunately, core recovery was poor at all sites, most likely due to the contrast in physical properties between poorly cemented, very soft carbonate ooze/chalk and well-cemented, very hard biosiliceous chert. Downhole geophysical logs from two sites (1207 and 1213) provide continuous, in situ records of physical and chemical properties that can be used to elucidate the sedimentary history of Shatsky Rise in the early Cretaceous. The downhole logs show that at both sites two stratigraphic intervals (dated as late Barremian-Aptian and early Albian) are characterised by low porosity, high resistivity sediments. The timing of these intervals is synchronous at both sites and it has been previously proposed that the 'resistivity highs' are the result of increased biosiliceous sedimentation and subsequent silica cementation. In order to test this hypothesis, we use matrix algebra to invert the logging data from Site 1207 to produce two compositional models - the first reconstructs lithology, the second reconstructs mineralogy. The results of the lithology model suggest that the abundance of chert is highest during the resistivity highs. The results of the mineralogical model are more complex because of the probable presence of additional minerals such as barite. Abstract Copyright (2008) Elsevier, B.V.
Year of Publication: 2008
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 20 Geophysics, Applied; Albian; Aptian; Barremian; Carbonate rocks; Chalk; Chemically precipitated rocks; Chert; Clastic sediments; Cretaceous; Downhole methods; Leg 198; Lithofacies; Lower Cretaceous; Mesozoic; Mineral composition; North Pacific; Northwest Pacific; ODP Site 1207; ODP Site 1213; Ocean Drilling Program; Ooze; Pacific Ocean; Pelagic sedimentation; Sedimentary rocks; Sedimentation; Sediments; Shatsky Rise; Well-logging; West Pacific
Coordinates: N374700 N374800 E1624600 E1624500
N313500 N313500 E1571800 E1571800
Record ID: 2009091491
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands