The Holocene 10,6 (2000) pp. 703–718 Bransfield Basin fine-grained sediments: late-Holocene sedimentary processes and Antarctic oceanographic conditions J. Fabre ´s, 1 A. Calafat, 1 * M. Canals, 1 M.A. Ba ´rcena 2 and J.A. Flores 2 ( 1 G.R.C. Geocie `ncies Marines, Departament d’Estratigrafia i Paleontologia, Universitat de Barcelona, Campus Universitari de Pebralbes, E-08028 Barcelona, Spain; 2 Departamento de Geologı ´a, Facultad de Ciencias, Universidad de Salamanca, E-37008 Salamanca, Spain) Received 28 July 1999; revised manuscript accepted 24 February 2000 Abstract: The Antarctic Peninsula is sensitive to climatic change due to its northerly position and to the relatively reduced volume and character of its ice cover. High-resolution palaeoclimatic records from the Ant- arctic Peninsula ice cores extend back only 500 years. A climatic record of 2850 years in the Bransfield Basin is investigated through the analysis of sediment gravity cores from the floor of the central subbasin (core GEBRA-1) and the slope of the eastern subbasin (core GEBRA-2). Sedimentological, mineralogical and geo- chemical properties have been systematically measured, together with Accelerator Mass Spectrometry (AMS) radiocarbon dating. The fine-grained sediments result from two main processes: hemipelagic settling from resuspensions and primary productivity, and turbidity currents. Hemipelagic sediments were selected to investi- gate the oceanographic and climatic conditions of the northern Antarctic Peninsula region during the last three millennia. Cold climatic periods are characterized by millimetric laminations and/or black layers with higher organic carbon, nitrogen and opal contents. Warm periods are recorded as massive to diffuse laminated facies with lower biogenic contents. The results include the ‘Little Ice Age’ (LIA) cold pulse as well as several 200– 300 year long fluctuations within the LIA and before this major climatic event of the Holocene. Key words: Bransfield Basin, late Holocene, marine sedimentology, geochemistry, palaeoceanography, palaeo- climatology, Antarctic. Introduction The increased interest in past climatic conditions, due to the need for an understanding of global climate and its fluctuations, has made possible the collection of palaeoclimatic records of different origin around the world. Detailed stratigraphy of deep-sea sedi- ment cores can provide information about palaeoceanographic aspects linked with climate evolution. Interest in the interpretation of the deep-sea sediment record in Antarctic Peninsula (AP) area is given by: (a) the environmental and ecological sensitivity of high-latitude areas covered by small ice caps to climatic change (Crowley and Baum, 1995); (b) the simple and high-speed response of those ice caps to climatic fluctuations (Barker et al., 1998); and finally (c) the lack of other kinds of high-resolution climatic records from this area for the last few thousand years (Leventer et al., 1996). * Corresponding author.  Arnold 2000 0959-6836(00)HL431RP A key point in palaeoenvironmental reconstructions from mar- ine sedimentary records is discriminating the different processes that control sedimentary particle deposition on the sea floor. The accurate determination of the contribution of each process is essential to assess the type and quality of the palaeoenvironmental information that will be extracted from the interpretation of a proxy. Sediments accumulated in deep areas of Bransfield subbasins have been described as opaline silica-rich muds and sandy muds with variable amounts of volcanic ash (Holler, 1989; Jeffers and Anderson, 1990; Yoon et al., 1994; Banfield and Anderson, 1995). Ba ´rcena et al. (1998) already published a first study on the micropalaeontogical content of GEBRA-1 and GEBRA-2 sedi- ments and its palaeoclimatic and palaeoceanographic significance. In the present study we focus on the sedimentary processes responsible for the accumulation of fine-grained sediments in the Bransfield Basin (BB) and on the likely regional and global sig-