CRUISE REPORT MARINE GEOLOGICAL CRUISE TO VESTFJORDEN AND EASTERN NORWEGIAN SEA R.V. Jan Mayen 29.05. -08.06. 2003 by Gaute Mikalsen Torbjørn Dalhgren DEPARTMENT OF GEOLOGY UNIVERSITY OF TROMSØ N-9037 TROMSØ, NORWAY Introduction The cruise was a joint cruse between four projects at The Department of Geology, University of Tromsø. For the last part of the cruise we were joined by one scientist and tow technicians from the Norwegian Collage of Fisheries, they embarked in Andenes. Their work spanned the last two days of the cruise And is not reported here. Objectives and Projects The main objective for this cruise was to retrieve sediment cores and seismics for the projects SPONCOM, NORDPAST-2, EUROSTRATAFORM and Dr. T. Dalhgrens project (Statoil). SPONCOM: “Sedimentary Processes and Palaeoenvironment on Northern Continental Margins” is a strategic university programme at Department of Geology, University of Tromsø founded by the Norwegian Research Council. The primary goal is to assess the changes in the physical environment of the seafloor and its overlying water and ice of West Spitsbergen and North Norwegian fjords and continental margin during the last glacial – interglacial cycle. On this cruise the aim was to retrieve material from North-Norwegian fjords and the continental margin elucidating the following sub goals: 1). The chronology and dynamics of the last glaciation – deglaciation. 2). Processes and fluxes of fjord, continental shelf and – slope sedimentation. 3). Rapid palaeoceanographic and palaeclimatic changes, particularly during the last deglaciation and the Holocene. NORPAST-2: “Past Climate of the Norwegian Region – 2” is a national project founded by the Norwegian Research Council. The primary goal is to advance the knowledge of patterns and variability of past climate in the Norwegian region and to contribute to the understanding of climate forcing factors. The material retrieved on this cruise aim to elucidate the following sub-goals: 1) Identify patterns and frequencies of natural climate variability on decadal to seasonal time scales during the last millennium. 2) Identify long term pattern and geographical distribution of gradual changes in natural climate during the Holocene and the late glacial. 2 3) Study the relative importance of the various forcing factors. 4) Investigate the origin of the climate during the recent past (natural/anthropogenic origin). 5) Develop, improve and test proxy methods for climatic reconstructions. EUROSTRATAFORM: The high-resolution seismic data acquired on the continental slope offshore Lofoten will be studied as part of the EU-funded EUROSTRATAFORM project (2002 - 2005). Our aim is to study canyon processes. The type of sediment transport into these systems is not known. At present they may act as a trap for sediments winnowed and transported by alongslope flowing ocean currents and/or they could be fed from upper slope mass wasting. During glacial periods glacigenic sediments provided additional sediment input. Our results will later be compared with studies of canyon processes on the non-glaciated margins offshore Portugal and the western Mediterranean. Project Dr. T. Dalhgren (Statoil): Seismic lines were acquired and a sediment core retrieved on the outermost Vøring Plateau and in the Lofoten Basin for a project supported by Statoil. The overall aim was to improve the chronology of seismic units in the area through ties to DSDP site 343, and to provide ties between already existing seismic lines. Seismic line 03JM0507 was received in order to extend and tie previous University of Tromsø lines (01-043 and 01-044) to DSDP site 343, in addition, these lines now provide a complete section of the slope from the Vøring marginal high down into the Lofoten basin. Seismic line 03JM0508 runs ENE from DSDP 343, the objective behind this line was to extend the chronology of this borehole to the margin off Lofoten. However, basement protrudes (volcanic mounds?) to seabed along a portion of this line, thus inhibiting such a correlation. Nevertheless, the line provides important ties for a number of University of Tromsø lines collected in 2002 in the Lofoten Basin, as well as, NPD lines on the Lofoten margin. The line also transverses the distal portion of the Trænadjupet Slide deposits. 3 Gravity core 03JM506 recovered 4.55 m of sediments from a low-accumulation area on the northeastern part of the Vøring Plateau. The locality has been identified from high-resolution seismics (line 03JM506), and Miocene sediments should occur below some 20-25 m of Pliocene to Pleistocene hemipelagics. The core was retrieved in order to provide knowledge of the characteristics of sediments in the area, such that long piston corers can be deployed safely at this location in the future. The locality offers a possibility to sample and date an early Pliocene unconformity in the area, as well as to recover a complete late Pliocene to Pleistocene sequence. Participants Dr. Gaute Mikalsen (Chief Scientist) Dr. Torbjørn Dahlgren Ing. Steinar Iversen Lab tek. Edel Ellingsen (29.05 to 06.06) Lab tek. Trine Dahl (29.05 to 0606) Ass Jan S Rørvik Equipment and methods. Box Corer The Box Corer samples the upper sea floor down to a maximum of 50 cm. Material retrieved consists of 50*50*max50 cm cube of sediment. If the sediment surface seemed intact, tubes with a diameter of 110mm was cored in to the sediment using a vacuum system. These cores were treated in two different ways, 1) the cores were stored upright and frozen. 2) the cores were slized in to 5mm slices and put on 96% alcohol with Bengal Stain. After a few hours the material was sieved on a 0.063mm sieve and then returned to alcohol with Bengal Stain. After c. 2 days the samples was sieved on 0.1 and 0.063 mm. 4 Gravity Corer The Gravity Corer is composed of a 6 m long steel pipe, with a core catcher in one end and c. 1.4 t heavy lead weight at the other end. Plastic liners with an outer diameter of 10 cm were used with the corer. Piston Corer The Piston corer has a 11.80 m long steel pipe (2 sections) and 1.6 t heavy lead weight. Plastic liners with an outer diameter of 10 cm were used also with this corer. Inside the liner is a piston that produces a vacuum as the corer penetrates in to the sediments, this allows longer cores to be sampled as compared to the gravity corer. The cores from both the GC and the PC was cut into c. 1m sections and logged on a MST-Logger. The material from the core catcher was sieved on 0.1mm and investigated for its foraminiferal content. Sleevegun array The high-resolution seismic data were aquired using an Sleevegun array composed of two 0,6 l guns together with a Fjord Instruments Streamer. The guns were towed in a steel frame 25 m behind the vessel at a water depth of 4 m. The firing pressure and the shooting rate was 130-140 bar and 8-10 s, respectively. The guns were tuned in order to obtain a spiked seismic source signal. The seismic records revealed a penetration of the sedimentary column in excess of 2 s TWT. Data were recorded digitally on a PC-based Delph2 recording and processing unit. The data were also printed online on a EPC 9800 printer. See the seismic log for details regarding filter settings, firing rate and pressure for the individual lines. Sparker A 9-electrode sparker was used together with the Fjord Instruments Streamer, the data were recorded on the Delph2 system and printed online on the EPC9800 printer. See the seismic log for details regarding the applied energy, shooting rate and filter settings for the individual lines. Pen Ecosonder The 3,5 kHZ echosounder data were acquired simultaneously to sleevegun/sparker profiling and the data were recorded on the Delph2 system, as well as printed online on the EPC9800 printer. A filter setting of 3-5 kHz was used. 5 Cruise Narrative Thursday 29.05: The ship was loaded with all equipment and left port in Tromsø at c. 12.00 local time. Overcast and calm sea. Wind was increasing approaching Vestfjorden. Friday 30.05: Strong winds make Piston coring dangerous, and no material could be retrieved with the Gravity Corer because of ship drift and heave. Four stations was left uncored. The ship entered Sagfjorden for shelter. One seismic line, one Gravity core and one Box Core was retrieved in this fjord. The ship heads towards Nordfolla, but is abrupt by a ship problem. F/F Jan Mayen has to be repaired and arrives in Svolvær at c. 20.00 local time. Saturday 31.05: Left Svolvær at 02.00 local time, the wind has decreased and the coring program in Vestfjorden is continued. Sunday 01.06: Calm wind and less sea. Samples were retrieved from the Trænadjupet area and Norskehavet. A suitable planned locality for Piston Coring was not found in the inner Trænadjupet. Monday 02.06: Calm sea and nice weather, seismic is running well. Tuesday 03.06: Calm sea overcast , Seismic is running well. Wednesday 04.06: Calm sea, foggy, Seismic is running well. Thursday 05.06: Nice weather, we returned to the stations that were aborted on Friday (30.05). One Piston Core station was not successful because of too little sediment. Short stop in Harstad to pick up some equipment for the boat. 6 Friday 06.06: Strong wind and high waves. The Gravity Core station west of Andenes was unsuccessful. Arrived of Andenes at 06.00 local time. Tow persons debarked and tree embarked by zodiac. Wind and waves decreases during the day. Saturday 07.06: Nice weather pen.