Setti, M et al. (2000): Geochemistry on smectites in sediment cores CRP-1 and CRP-2 from the Ross Sea, Antarctica. doi:10.1594/PANGAEA.510756, Supplement to:Setti, Massimo; Marinoni, L; Lopez-Galindo, A; Delgado-Hubertas, A (2000): Compositional and morphological features of the smectites of the sediments of CRP-2/2A, Victoria Land Basin, Antarctica. Terra Antartica, 7(4), 581-587, hdl:10013/epic.28251.d001
TEM (transmission electron microscopy) observations and microanalyses on smectite microparticles in the sediments of the CRP-2A core were carried out to determine their origin (authigenic or detrital) and the source rocks. Smectites are dioctahedral and are Fe-rich members of the nontronite-beidellite series. They generally display both flaky and hairy shapes, but no large compositional difference between the two forms was observed. Flaky smectites are detrital while hairy smectites probably formed in situ through the reorganisation of previous flaky particles. The source rocks for smectites are probably represented by the McMurdo Volcanic Group to the south, but also by the Ferrar Dolerites and Kirkpatrick Basalts in the Transantarctic Mountains. CRP-2A smectites are Fe and Mg richer than those of the coeval or not coeval levels of the CIROS-I, DSDP 270 and 274 cores. The average compositions of smectite in CRP-1 and CRP-2A cores show a downcore trend toward more alluminiferous terms, which might reflect the increase of the chemical weathering processes on the continent.
CRP-1 (16 km ENE Cape Roberts) * Latitude: -77.007580 * Longitude: 163.755080 * Date/Time Start: 1997-10-17T01:30:00 * Date/Time End: 1997-10-24T02:00:00 * Elevation: -153.5 m * Penetration: 132.06 m * Recovery: 113.32 m * Location: off Cape Roberts, Ross Sea, Antarctica * Campaign: CRP-1 * Basis: Sampling/drilling ice * Device: Core wireline system (CWS) * Comment: sea ice thickness: 1.60 m, recovery 86 %. Age and lithology of oldest strata: 22-24 Ma; mudstone with scattered pebbles.
CRP-2A (14.2 km at 096° true from Cape Roberts) * Latitude: -77.005980 * Longitude: 163.719450 * Date/Time Start: 1998-10-16T07:30:00 * Date/Time End: 1998-11-25T14:20:00 * Elevation: -177.9 m * Recovery: 624 m * Location: off Cape Roberts, Ross Sea, Antarctica * Campaign: CRP-2 * Basis: Sampling/drilling from ice * 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. 13.03 to 45.97 mbsf, 11.29 m (34%) partially following CRP-2. 45.07 to 624.15 mbsf, 548.67 m (95%) new hole. Deepest core-lithology: hard sandy siltstone. Deepest core-age: earliest Oligocene (ca. 33 Ma on diatoms, nannofossils and dinoflagellates)