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Naish, Tim R; Barrett, Peter J; Dunbar, Gavin B; Woolfe, Ken; Dunn, A G; Henrys, Stuart A; Claps, Michele; Powell, Ross; Fielding, Christopher R (2001): Grain size analysis on CRP sediment cores from the Ross Sea, Antarctica. PANGAEA,, Supplement to: Naish, TR et al. (2001): Sedimentary cyclicity in CRP drillcore, Victoria Land Basin, Antarctica. Terra Antartica, 8(3), 225-244, hdl:10013/epic.28205.d001

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The upper 1200 m of pre-Pliocene sediment recovered by Cape Roberts Project (CRP) drilling off the Victoria Land coast of Antarctica between 1997-1999 has been subdivided into 54 unconformity-bound stratigraphic sequences, spanning the period c. 32 to 17 Ma. The sequences are recognised on the basis of the cyclical vertical stacking of their constituent lithofacies, which are enclosed by erosion surfaces produced during the grounding of the advancing ice margin onto the sea floor. Each sequence represents deposition in a range of offshore shelf to coastal glacimarine sedimentary environments during oscillations in the ice margin across the Western Ross Sea shelf, and coeval fluctuations in water depth. This paper applies spectral analysis techniques to depth- and time-series of sediment grain size (500 samples) for intervals of the core with adequate chronological data. Time series analysis of 0.5-l.0m-spaced grainsize data spanning sequences 9-11 (CRP-2/2A) and sequences 1-7 (CRP-3) suggests that the length of individual sequences correspond to Milankovitch frequencies, probably 41 k.y., but possibly as low as 100 k.y. Higher frequency periodic components at 23 k.y. (orbital precession) and 15-10 k.y. (sub-orbital) are recognised at the intrasequence-scale, and may represent climatic cycles akin to the ice rafting episodes described in the North Atlantic Ocean during the Quaternary. The cyclicity recorded by glacimarine sequences in CRP core provides direct evidence from the periphery of Antarctica for orbital oscillations in the size of the Oligocene-Early Miocene East Antarctic Ice Sheet.
Median Latitude: -77.005992 * Median Longitude: 163.719225 * South-bound Latitude: -77.006000 * West-bound Longitude: 163.719000 * North-bound Latitude: -77.005983 * East-bound Longitude: 163.719450
Date/Time Start: 1998-10-01T00:00:00 * Date/Time End: 1999-11-19T00:00:00
CRP-2 (14.2 km at 096° true from Cape Roberts) * Latitude: -77.005983 * Longitude: 163.719450 * Date/Time: 1998-10-01T00:00:00 * Elevation: -177.9 m * Recovery: 57.42 m * Location: off Cape Roberts, Ross Sea, Antarctica * Campaign: CRP-2 * Basis: Sampling/drilling from ice * Method/Device: Core wireline system (CWS) * Comment: 921 m at 284° from CRP-1. Sea-ice thickness: 2.0 m (1 Oct) to 2.2 m (23 Nov). Sea riser embedded to 13.03 mbsf. Lateral ice movement: 9.87 m to east from 17 Oct to 23 Nov. HQ core to 199.31 mbsf. NQ core to 624.15 mbsf
CRP-3 * Latitude: -77.006000 * Longitude: 163.719000 * Date/Time Start: 1999-10-09T00:00:00 * Date/Time End: 1999-11-19T00:00:00 * Elevation: -295.0 m * Penetration: 939 m * Recovery: 936 m * Location: Ross Sea * Campaign: CRP-3 * Basis: Sampling/drilling from ice * Method/Device: Core wireline system (CWS) * Comment: 11.76 km at 76° true from Cape Roberts, 2.04 km at 225° true from CRP-2. Fast ice thickness: 2.0 to 2.2 m. Sea rise embedded to 9.55 mbsf. Lateral ice movement from spudding 5.0 m to 82° true. HQ core to 345.85 mbsf. NQ core to 939.42 mbsf. Core recovery 97%. Phase 1 logging to 345 mbsf, Phase 2 logging to 773 mbsf, Phase 3 logging to 918 mbsf. Deepest Cenozoic lithology and depth: sandstone breccia from 822.87 to 823.11 mbsf. Age of oldest Cenozoic strata: earliest Oligocene or latest Eocene. Deepest core lithology and depth: light red-brown quartz-cemented quartz sandstone to 939.42 mbsf. Age of bedrock: (mid?) Devonian.
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