Laser-Derived Particle Size Data from CRP-3, Victoria Land Basin, Antarctica: Implications for Sequence and Seismic Stratigraphy

• Main Authors: Fielding, Christopher R., Dunbar, G. B, Bryce, S. M
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2001
• Subjects: Earth Sciences; Victoria Land; Antarc*; Antarctica
• Online Access: https://digitalcommons.unl.edu/geosciencefacpub/142; https://digitalcommons.unl.edu/context/geosciencefacpub/article/1143/viewcontent/Fielding_TA_2001_Laser_derived_particle.pdf

Seven hundred and nineteen samples from throughout the Cainozoic section in CRP-3 were analysed by a Malvern Mastersizer laser particle analyser, in order to derive a stratigraphic distribution of grain-size parameters downhole. Entropy analysis of these data (using the method of Woolfe & Michibayashi, 1995) allowed recognition of four groups of samples, each group characterised by a distinctive grain-size distribution. Group 1, which shows a multi-modal distribution, corresponds to mudrocks, interbedded mudrock/sandstone facies, muddy sandstones and diamictites. Group 2, with a sand-grade mode but showing wide dispersion of particle size, corresponds to muddy sandstones, a few cleaner sandstones and some conglomerates. Group 3 and Group 4 are also sand-dominated, with better grain-size sorting, and correspond to clean, well-washed sandstones of varying mean grain-size (medium and fine modes, respectively). The downhole disappearance of Group 1, and dominance of Groups 3 and 4 reflect a concomitant change from mudrock- and diamictite-rich lithology to a section dominated by clean, well-washed sandstones with minor conglomerates. Progressive downhole increases in percentage sand and principal mode also reflect these changes. Significant shifts in grain-size parameters and entropy group membership were noted across sequence boundaries and seismic reflectors, as recognised in other studies.