491 Netherlands Journal of Sea Research 24 (4): 491-494 (1989) LATE QUATERNARY PALAEOCEANOGRAPHY OF THE BANDA SEA, EASTERN INDONESIAN PISTON CORES (SNELLIUS-II EXPEDITION, CRUISE G5) G. GANSSEN 1, S.R. TROELSTRA 1, B. FABER 1, W.A. VAN DER KAARS 2 and M. SITUMORANG 3 1Geomarine Centre Amsterdam, Institute of Earth Sciences, Free University, RO. Box 7161, 1007 MC Amsterdam, The Netherlands 2Department of Palynology and Palaeo/Actuo Ecology, Hugo de Vries Laboratory, Kruislaan 318, 1098 SM Amsterdam, The Netherlands 3Marine Geological Institute, Ministry of Mines and Energy, JI. Dr Junjunan 236, Bandung 40174, Indonesia ABSTRACT Two Banda Sea piston cores were analysed for CaCO 3 content, foraminiferal, radiolarian and spore-pollen distribution, and for oxygen and car- bon isotopes. Late Quaternary palaeoclimatology and -oceanography are deduced. In this tropical area the two-step deglaciation is seen in the oxy- gen isotope profile. It did not lead to higher sur- face water temperatures but to a wetter climate as recorded in concurrent changes of the palynofa- cies. The core record further shows effects of an increasing monsoon regime on ocean circulation and land climate around 10 ka. At about 10.5 ka cli- mate got wetter, while upwelling intensity in- creased around 9.2 ka and monsoonal intensity decreased again at about 2.7 ka. 1. INTRODUCTION Since the first Snellius Expedition (1929/30) the Ban- da Sea is known as an area where extremely high sediment accumulation rates occur, due to large ter- rigenous input. One of the main objectives of theme 1 of the Snellius-II Expedition was to characterize Banda Sea depositional environments (TROELSTRA et al., 1989). To achieve this, three transects across the island arc system have been sampled systematically during Cruise G5 when R.V. 'Tyro' took 142 box cores and 34 piston cores (see Snellius-II reports (in prep.) for core descriptions). The objective of this study is to reconstruct climatic and oceanographic changes during the last deglaci- ation using different disciplines: the micropalaeontol- ogy of pollen and spores, radiolaria, and foramini- fera, as well as stable oxygen and carbon isotopes, and 140 distribution. We used two piston cores selected on the CaCO 3 stratigraphy for undisturbed, continuous marine sediments (Fig. 1, Table 1). Acknowledgements,--Research has been carried out as a part of the Snellius-II Expedition, organized by the Indonesian Institute of Science (LIPI) and the Netherlands Council of Oceanic Research (NRZ). The authors would like to thank Dr. K. Van den Borg (Utrecht) for providing AMS 14C-data, and Prof. Dr. Willkomm and Dr. Erlenkeuser (Kiel, FRG) for access to their mass spectrometer facilities. Critical review and helpful discussions by J.E. Van Hinte are ap- preciated. This is contribution no 50 of the Geo- marine Centre Amsterdam. 2. METHODS Palynological preparation techniques are described by VAN DER KAARS (1989). For the micropalaeontolog- ical analysis of planktonic foraminifera and radiolaria about 10 cm 3 of sediment was washed over a 63 #m mesh sieve and dried at 50°C. From this residue about 10 specimens of the planktonic foraminifer Globigerinoides ruber were picked in the size fraction 250 to 400 ~m for isotope analysis (GANSSEN, 1986). The isotopic difference between sample-CO 2 and the PDB standard is reported in %0. Measurements were carried out on a Finnigan MAT 251 mass spec- trometer, partly in Amsterdam, partly with a fully auto- mated preparation device in Kiel (FRG). Standard deviation is 0.08 and 0.12%0 for ~180 and 0.12 and 0.09%o for (~13C in Kiel and Amsterdam, respectively. Reproducibility of samples measured in both labs is less than 0.10%0 for both (~180 and (~130. 10 mg calcium-carbonate of well preserved plank- tonic foraminifera from the >250 #m fraction was used for 14C-age determinations with the Accelera- tion Mass Spetrometer of the Van der Graaff Labora- tory at the University of Utrecht. Correction is applied for isotope fractionation by normalization with known (~130 tO (~130=-25%0. No correction has been applied for reservation age. 3. RESULTS AND DISCUSSION 3.1. CORE G5-6-149P Analytical results for core G5-6-149P are given in Fig. 2. The CaCO 3 pattern of increasing values in the up- per two metre of the core (Fig. 2a) suggests that we