Geochemistry on smectites in sediment cores CRP-1 and CRP-2 from the Ross Sea, Antarctica

• Main Authors: Setti, Massimo, Marinoni, L, Lopez-Galindo, A, Delgado-Huertas, Antonio
• Format: Dataset
• Language: English
• Published: PANGAEA 2000
• Subjects: 14.2 km at 096° true from Cape Roberts; 16 km ENE Cape Roberts; Cape Roberts Project; Core wireline system; CRP; CRP-1; CRP-2; CRP-2A; CWS; off Cape Roberts; Ross Sea; Antarctica; Sampling/drilling from ice; Sampling/drilling ice; Cape Roberts; Roberts Cape; Transantarctic Mountains; Antarc*
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.510756; https://doi.org/10.1594/PANGAEA.510756

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.