Final conference, Rome October 11, 2016 Extreme Meltwater events in the Arctic: the marine sedimentary record of Meltwater Pulse 1a R.G. Lucchi1, L. Sagnotti2, A. Camerlenghi1, P. Macri2, M. Rebesco1, Giorgetti3 1 Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42c, 34010 Sgonico (TS), Italy (rglucchi@inogs.it); 2 Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Roma, Italy. 3 Dipartimento di Scienze fisiche, della Terra e dell’ambiente, Via Laterina 8, 53100 Siena, Italy. Abstract The upper continental slope of the Storfjorden-Kveithola Trough Mouth Fans (NW Barents Sea) contains a several m-thick late Pleistocene sequence of ice meltwater derived deposits (plumites). Radiocarbon ages revealed that deposition occurred during about 130 years at a very high sedimentation rate of 3.4 cm a-1. Palaeomagnetic and rock magnetic analyses confirm the existence of a prominent, short-living sedimentary event. On the acoustic record the plumites appear laterally continuous and were correlated with the sedimentary sequences described west of Svalbard and neighbouring glacial depositional systems representing a major event at regional scale that was appointed to correspond to the deep-sea sedimentary record of the Meltwater Pulse-1a. Introduction A meltwater pulse (MWP) is a short-lived, global acceleration in sea-level rise resulting from intense front- and subglacial meltwater release, surging ice-streams into oceans and iceberg discharge during ice-sheets disintegration. Four main meltwater pulses have been pointed to have occurred during the last deglaciation phase: MWP-19ka, also known as MWP-1a0, about 19 cal ka BP (Clark et al. 2004); MWP-1a, 14.650- 14.310 cal a BP (Deschamps et al. 2012); MWP- 1b, 11.500-11.000 cal a B.P. (Bard et al. 2010); and MWP-1c at about 8.000 cal a BP (Harris et al. 2008). Of these events, MWP-1a was possibly the most prominent leading to a global sea-level rise of about 20 m in the course of 340 a (Deschamp et al. 2012). Evidences of the existence MWP-1a have been found in many low-latitude areas but straightforward evidence is still lacking in polar areas where the event is thought to have originated. Four ice-sheets are considered as possible candidates responsible for shaping the global sea-level curve: the Laurentide, Fennoscandian, Barents and Antarctic ice-sheets. Scarce and ambiguous evidences of MWP-1a imprints in the polar areas are puzzling and do not help resolve the controversy on its origin. Ten sediment cores collected during the projects SVAIS (2007), EGLACOM (2008), and CORIBAR (2013) on the Storfjorden-Kveithola TMFs (Fig. 1), evidenced the existence of a prominent interlaminated deposit that in the upper slope is over 4.5 m- thick. Sub-bottom profiles indicate that this deposit is continuously distributed over the area reaching thickness of 20 m offshore the Storfjorden lobe III and Kveithola Trough (Fig. 1). The sediments cores were analyses for physical, compositional and palaeomagnetic characteristics. The age model was based on rocks palaeomagnetic parameters and 50 C14 radiometric dating. Figure 1: Map of the study area with inferred direction of the main ice streams during LGM. Red dots indicate the location of the studied cores. SV=SVAIS cores; EG= EGLACOM; C=CORIBAR; GZW=Grounding Zone Wedges. ( ( ( ( ( ( 1 1  ( 12'$7$    NLORPHWUHV %-51<$ 63,76%(5*(1 .9(,7+2/$ 70) 1 ( ' 5 2 - ) 5 2 7 6 ) 0 7 12'$7$ 1 ( ' 5 2 - ) 5 2 7 6 0 $ ( 5 7 6  ( & , 2 ( / $ 3 ',67$/,&( 6285&(6 352;,0$/ ,&(6285&( .9(,7+2/$ 3$/(2,&(675($0 352;,0$/ ,&(6285&( , ( % 2 / ,, ( % 2 / ,,, ( % 2 / 68%, &( 67 5( $0 , 68%,& ( 6 75($0 , , 6 8%,&( 67 5($ 0 ,,, 68%,&( 675($0 287(5 %$1. 287(5 %$1. 125' )/$.(7 68%0$5,1( /$1'6/,'(6                                  1 ( * 5 ( % 6 7 , 3 6 1 ( . 1 $ % ' ( 6 $ %  ( 1 , 5 $ 0 ( 0 2 '  ( & , 352;,0$/ ,&(6285&(   