R/V “Hans Brattstrøm”

(1)

Marine Geological/Geophysical Cruise Report

from

Byfjorden and Herdlefjorden

R/V “Hans Brattstrøm”

UoB Cruise No. HB-12-176

19. - 23. September 2012

H.F. Kleiven J. Brendryen

S. Monsen

&

Student Team

University of Bergen, Department of Earth Science, Allegt. 41, N-5007 Bergen, Norway

(2)

Bibliographic reference:

Kleiven, H.F., Brendryen, J., Monsen, S. & Student Team, 2012. Marine Geological/Geophysical Cruise Report from Byfjorden, Herdlefjorden and Salhusfjorden. Report No. 100-03/12, Department of Earth Science, University of Bergen, Bergen, Norway, 21 pp.

University of Bergen

Department of Earth Science Allegt. 41,

N-5007 Bergen, Norway First Published 2012

ISSN

(3)

CONTENT

1. INTRODUCTION 1

1.1. Objectives 1 1.2. Scientific party 1

2. RESEARCH VESSEL and EQUIPMENT 2 2.1. Research vessel 2 2.2. Equipment 2 3. FIELD OPERATIONS 5

3.1. Weather and sea state conditions 5 3.2. Equipment Performance 5 3.3. General cruise performance 5

Figure 1: Overview map 6

Figure 2: Sub-bottom profile from Byfjorden Day 1 8 Figure 3 Sub-bottom profile from Byfjorden Day 2 9 Figure 4: Sub-bottom profile from Byfjorden Day 2 10

Figure 5: Sub-bottom profile from Herdlefjorden Day 3 11

Figure 6: Sub-bottom profile from Herdlefjorden Day 3 12

Figure 7: Sub-bottom profile from Byfjorden Day 4 13

Figure 11: CTD profile from Byfjorden 17

Figure 13: CTD profile from Herdlefjorden 18

Table I: Station Log 7

Table II: Survey Log 20

Table III: Sub-bottom profile Log 21

(4)

1. INTRODUCTION

1.1. Objectives

The marine geology cruise to Byfjorden and Herdlefjorden onboard R/V Hans Brattstrøm (Fig.

1) is an integrated part of the Department of Earth Science course GEOV108 “Introduction to marine geology and geophysics”. The students enrolled on the course are divided into five groups, each participating on a one-day cruise. The main objective of the cruise is to introduce the students to basic research techniques involved in marine geology sea studies.

This report gives a summary of the equipment used onboard R/V Hans Brattstrøm during the cruise and information on the seismic survey and stations that were chosen en-route. Figure 1 shows the survey areas and general survey logs are provided in Table I and II.

1.2. Scientific Party

Helga (Kikki) F. Kleiven UoB Lecturer, cruise leader

Jo Brendryen UoB Lecturer

Stig Monsen UoB Technician

Ole Meyer UoB Technician (Tuesday 18.09.2012)

Student team – UoB

Tale Maria Aabø, Kristian Albrektsen, Alan Amin, Torbjørn Andersson, Jørgen Bergeland, Annett Bergset, Merethe Bryn, Jørn Buch, Camilla Maria Christensen, Lars Tveit Christiansen, Karianne Drage, Tor Ellingsen, Cathrine Espeland, Håvard Fiksen, Heidi Synnøve Fossmark, Lina Gislefoss, Barbara Hansen, Emil Hansen, Audun Hegna, Linn Therese Heienberg, Thea Heimdal, Charlotte Helleland, Magnus Herrem, Marie Hesjedal, Frode Hoang, Ole Johan Hornenes, Morten Hovland, Heidi Ims, Martine Johnsen, Knut Jørgensen, Fredrik Sebastian Kjelkenes, Felix Kluge, Andreas Kongsgården, Johne Landa, Marie Larsen, Mette Lundberg, Bratje Lønøy, Sturla Meling, Anders Meltveit, Vetle Nordang, Kjersti Nylend, Ida Synnøve Olsen, Birgitte Opås, Åge Paulsen, Emilie Randeberg, Andreas Rasmussen, Maria Helena Seim, Jostein Soldal, Christian Solheim, Ole Christian Sollie, Maria Straume, Matias Sundal, Martin Sæterhaug, Christoffer Taule, Marita Thomassen, Linda Thorsen, Elin Thorsheim, Thomas Thuesen, Magnhild Torper, Anna Tran, Indun Vefring, Torbjørn Veland, Eirik Vårdal, Einar Øyehaug.

UoB: University of Bergen, Dept. of Earth Science, Allegt. 41, 5007 Bergen, Norway

(5)

RESEARCH VESSEL and EQUIPMENT

2.1. Research vessel

R/V Hans Brattstrøm is 24.3 m long, with a beam of 6.5 m, a displacement of 97 tonnes, and a top speed of 13 knots. The research vessel is owned by the University of Bergen and is operated by the Institute of Marin Research, Bergen. The main duties are research operations within the areas of fishery, environment research, seabed sampling and educational surveys with students. The research vessel has a crew of 2, and operates in the coastal areas out to 20 nautical miles from the coast.

2.2. Equipment

A sub-bottom profiler (SBP), SB-216S from EdgeTech, was used throughout the entire cruise to map the characteristics of the sub-seabed sediments (Figs. 2-10/Table III). The profiler operates in the frequency range of 2-16 kHz. The profiler has a theoretical penetration of up to 60 m. The profiler was towed behind the vessel, at a level of 1-2 m below the sea surface.

Sub-bottom profiler used during the cruise. (Photo: Eva Bjørseth; February 2009)

(6)

Throughout the entire cruise a box core was used to collect samples from the upper part of the sediment column (Fig.1; Table II).

Box core used during the cruise. (Photo: Eva Bjørseth; February 2009)

CTD profiles were collected in Byfjorden and Herdlefjorden (Figs. 1, 11-15; Table I). The CTD was connected to a winch, and lowered to the seabed before withdrawal.

CTD used on cruise.

(7)

Gravity cores with a core barrel length of 2.5 m were collected at five locations (Fig. 1, Table I).

Gravity corer used during the cruise. (Photo: Eva Bjørseth; February 2009)

(8)

3. FIELD OPERATIONS

The students were divided into five groups and each group had one day onboard the R/V Hans Brattstrøm. Totally, 63 students participated. A summary of the ship-board operations and ship survey is provided in Tables I and II

3.1. Weather and sea state conditions

The weather conditions during the cruise were generally good for surveying. The sea state was calm, with waves less than 1 m.

3.2. Equipment performance

• We had problems obtaining high-resolution data from the chirp the first day of the cruise.

However, the chirp functioned well during the rest of the survey days, and the data collected had an overall good quality. The sub-seafloor penetration depended very much on the sediment characteristics.

• The box corer functioned well throughout the cruise. One surface sediment sample was collected on station every day for further analyses at Department of Earth Science, UoB.

Pure alcohol (96%) and Rose Bengal was added to these samples.

• The gravity coring system was used without any problems, except for the first try at Station 1 where the core barrel was empty, presumably due to rocks and anthropogenic debris at the sediment surface as documented by sediments retrieved by the box core (HB12-176-01BC). The second try at a new location (Table I) was successful. The five gravity cores raised were labeled and transported to the Department of Earth Science, UoB, for further analyses and storage.

• The CTD functioned well throughout the cruise.

3.3. General cruise performance

• 5 box cores, 5 gravity cores and 5 CTD profiles were collected (Table I).

• A total of 10 seismic profiles were collected (Table III)

(9)

Figure 1. Overview map, showing locations of box cores, gravity cores and CTD stations (black dots). Red lines indicate approximate position of sub bottom profiles.

(10)

Table I. Overview of stations and activities during the HB12-176 student cruise

HB12-176 station 01-05 Activity Longitude Latitude

CRUISEDAY 1; 17.09.12 Lengthprofile, LP1 60° 24,036’N 005° 18.725’E

Byfjorden 60° 24.101’N 005° 18.299’E

60° 24.912'N 005° 17.666'E

Crossingline, TP1 60° 24.603'N 005° 18.187'E 60° 25.048'N 005° 17.053'E CTD & BC 60° 24.541'N 005° 18.427'E GC (new station) 60° 25.106'N 005° 16.698'E

CRUISEDAY 2; 18.09.12 Lengthprofile, LP2 60° 24.102'N 005° 17.196'E

Byfjorden 60° 25.287'N 005° 16.598'E

Crossingline, TP2 60° 25.105'N 005° 17.202'E 60° 25.086'N 005° 16.159'E CTD, BC, GC 60° 25.092'N 005° 16.559'E

Herdlefjorden 60° 30.750'N 005° 10.630'E

Byfjorden 60° 28.342'N 005° 14.824'E

Crossingline, TP4 60° 27.925'N 005° 16.019'E 60° 27.738'N 005° 14.431'E

CTD 60° 26.422'N 005° 16.035'E

BC (new station) 60° 26.557'N 005° 15.944'E GC (new station) 60° 27.423'N 005° 15.382'E

Byfjorden 60° 26.429'N 005° 15.978'E

(11)

Figure 2. Sub-bottom profile (LP1) across Station 01 area in Byfjorden. Station location in Fig. 1/Table I

(12)

Figure 3. Sub-bottom profile (LP2) from Byfjorden.

Location in Fig. 1/Table I

(13)

Figure 4. Sub-bottom profile (TP2) from Byfjorden. Location in Fig. 1/Table I.

(14)

Figure 5. Sub-bottom profile, (LP3), from Herdlefjorden. Location in Fig. 1/Table I.

(15)

Figure 6. Sub-bottom profile, (TP3), from Herdlefjorden. Location in Fig. 1.

(16)

Figure 7. Sub-bottom profile, (LP4), from Byfjorden. Location in Fig. 1/Table I.

(17)

Figure 8. Sub-bottom profile, (TP4), from Byfjorden. Location in Fig. 1/Table I.

(18)

Figure 9. Sub-bottom profile, (LP5), from Byfjorden. Location in Fig. 1/Table I.

(19)

Figure 10. Sub-bottom profile, (TP5), from Byfjorden. Location in Fig. 1/Table I.

(20)

Figure 11. CTD profile HB-12-176-01CTD collected in Byfjorden 17.09.12 Position in Fig. 1. Red curve is salinity and green curve is temperature.

Figure 12. CTD profile HB-12-176-02CTD collected in Byfjorden 18.09.12. Position in Fig. 1. Red curve is salinity and green curve is temperature.

(21)

Figure 13. CTD profile HB-12-176-03CTD collected in Herdlefjorden 19.09.12. Position in Fig. 1. Red curve is salinity and green curve is temperature.

(22)

(23)

Table II The survey log for student cruise HB12-176

Table I

General Survey log

GEOV108 student cruise HB-12-176, R/V Hans Brattstrøm

Date Time Subject

17.09.2012 08:45 – 10:00 Mobilization at Nykirkekaien.

10:30-14:00 Collection of seismic profiles, CTD, box core and gravity core from Byfjorden 14:30 End of day, arriving Nykirkekaien

18.09.2012

09:10 Leaving Marineholmen

09:30-14:15 Collection of seismic profiles, CTD, box core and gravity core from Byfjorden 14:30 End of day, arriving Marineholmen

19.09.2012

09:30:00-13:45 Collection of seismic profiles, CTD, box core and gravity core from Herdlefjorden

14:00 End of day, arriving Marineholmen.

20.09.2012

10:15-13:30 Collection of seismic profiles, CTD, box core and gravity core from Byfjorden

14:30 End of day, arriving Marineholmen. 09:00 Leaving Nykirkekaien

21.09.2012

09:10

Leaving Marineholmen 10:00-14:00 Collection of seismic profiles, CTD, box core and gravity core from

Herdlefjorden

09:45-13:00 Collection of seismic profiles, CTD, box core and gravity core from Byfjorden 14:30 End of day, arriving Nykirkekaien. End of cruise 13:15 End of day, arriving Nykirkekaien. Demobilization. End of cruise

(24)

Table III Overview of the sub-bottom profiles collected during the HB12-176 student cruise

Table III Seismic profiles

File name Date Location

LP1 17.09.12 Byfjorden

TP1 17.09.12 Byfjorden

LP3 19.09.12 Herdlefjorden TP3 19.09.12 Herdlefjorden