Clay-mineral composition and biogenic opal content of Late Neogene to Quaternary sediments of the Antarctic Peninsula region

• Main Authors: Hillenbrand, Claus-Dieter, Ehrmann, Werner
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2005
• Subjects: 178-1095; 178-1096; 178-1101A; ANT-IV/4; ANT-VI/3; ANT-VIII/6; Atka Bay; COMPCORE; Composite Core; DRILL; Drilling/drill rig; Fram Strait; Giant box corer; GKG; Gravity corer (Kiel type); Joides Resolution; Leg178; Maud Rise; Ocean Drilling Program; ODP; Polarstern; PS08; PS08/564; PS12; PS12/291; PS1451-1; PS1588-1; PS1588-3; PS16; PS16/541; PS1824-1; PS1824-2; SL; South Pacific Ocean; Antarc*; Antarctic; Antarctic Peninsula; Bellingshausen Sea; Ice cap; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.735191; https://doi.org/10.1594/PANGAEA.735191

Clay-mineral composition and biogenic opal content in upper Miocene to Quaternary drift sediments recovered at two Ocean Drilling Program (ODP) sites from the continental rise in the Bellingshausen Sea had been analyzed in order to reconstruct the climatic and glacial history of the Antarctic Peninsula. The clay mineral composition at both sites is dominated by smectite, illite, and chlorite, and alternates between a smectite-enriched and a chlorite-enriched assemblage throughout the last 9.3 my. The spatial distribution of clay minerals in Holocene sediments west of the Antarctic Peninsula facilitates the identification of particular source areas, and thus the reconstruction of transport pathways. The similarity to clay mineral variations reported from upper Quaternary sequences suggests that the short-term clay-mineralogical fluctuations in the ODP cores reflect glacial-interglacial cyclicity. Thus, repeated ice advances and retreats in response to a varying size of the Antarctic Peninsula ice cap are likely to have occurred throughout the late Neogene and Quaternary. The clay minerals in the drift sediments exhibit only slight long-term variations, which are caused by local changes in glacial erosion and in supply of source rocks, rather than by major climatic changes. The opal records at the ODP sites are dominated by long-term variations since the late Miocene. We infer that the opal content in the drift sediments, although it is influenced by dissolution in the water column and the sediment column and by the burial with lithogenic detritus, provides a signal of paleoproductivity. Because the annual sea-ice coverage is regarded as the main factor controlling biological productivity, the opal signal helps to reconstruct paleoceanographic changes in the Bellingshausen Sea. Slightly enhanced opal deposition during the late Miocene indicates slightly warmer climatic conditions in the Antarctic Peninsula area than at present. During the early Pliocene, enhanced opal deposition in the Pacific sector of the ...