Mineralogical and grain size analysis of ODP Hole 119-745B from the Southern Ocean, supplement to: Ehrmann, Werner; Grobe, Hannes (1991): Cyclic sedimentation at sites 745 and 746. In: Barron, J; Larsen, B; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 119, 225-237


The upper Miocene to Pleistocene sediments recovered at ODP Sites 745 and 746 in the Australian-Antarctic Basin are characterized by cyclic facies changes. Sedimentological investigations of a detailed Quaternary section reveal that facies A is dominated by a high content of siliceous microfossils, a relatively low terrigenous sediment content, an ice-rafted component, low concentrations of fine sediment particles, and a relatively high smectite content. This facies corresponds to interglacial sedimentary conditions. Facies B, in contrast, is characteristic of glacial conditions and is dominated by a large amount of terrigenous material and a smaller opaline component. There is also a prominent ice-rafted component. The microfossils commonly are reworked and broken. The clay mineral assemblages show higher proportions of glacially derived illite and chlorite. A combination of four different processes, attributed to glacial-interglacial cycles, was responsible for the cyclic facies changes during Quaternary time: transport by gravity, ice, and current and changes in primary productivity. Of great importance was the movement of the grounding line of the ice shelves, which directly influenced the intensity of ice rafting and of gravitational sediment transport to the deep sea. The extension of the ice shelves was also responsible for the generation of cold and erosive Antarctic Bottom Water, which controlled the grain-size distribution, particularly of the fine fraction, in the investigated area.

DOI https://doi.org/10.1594/PANGAEA.587844
Related Identifier https://doi.org/10.2973/odp.proc.sr.119.123.1991
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.587844
Creator Ehrmann, Werner; Grobe, Hannes
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 1991
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Language English
Resource Type Supplementary Collection of Datasets; Collection
Format application/zip
Size 5 datasets
Discipline Earth System Research
Spatial Coverage (85.854 LON, -59.595 LAT); Indian Ocean
Temporal Coverage Begin 1988-02-09T15:30:00Z
Temporal Coverage End 1988-02-10T17:15:00Z