S XVIIl2 E 2001 (Arctic Mid-Ocean Ridge Expedition) by J. Thiede and the Shipboard cientific Party Ber. Polarforsch. Meeresforsch. 421 (2002) ISSN 1618 - 3193 POLARSTERN ARK XVIIl2 CRUISE REPORT I FAHRTBERICHT: AMORE 2001 by J.Thiede and the Shipboard Scientific Party Contents Page AMORE 2001 : Executive Summary...................................................... 4.33 AMORE 2001 : Zusammenfassung ...................................................... 7% Introduction .......................................................................................................10 Structure and Composition of the Crust in the Eastern Arctic Ocean......................................................................................................... 10-13 The Partner Ship USCGC HEALY ...................................................... 1.337 Joint Operations of HEALY and POLARSTERN .............................1-8-20 Short Biography of Yakov Gakkel ....................................................... 21-22 . Expedition Narrative .............................................................................. 2340 Meteorological Conditions ................................................................4E.49 Sea Ice Measurements and Samplfng ................................................. 50 Ice Conditions along the Cruise Track ................................................ 51-53 NOAA-AVHRR Imagery........................................................................ 53-56 Ice Thickness Measurements................................................................ 56-67 Laser Profiling of Pressure Ridges ...................................................... 67-69 Spectral Albedo and Areal Coverage of Various Surface Types ..70-75 Salinity. Density and Texture of Ice Cores......................................... 76-77 The Role of Sea Ice On the Transport of Radionuclides ................. 77-79 Biological Studies.................................................................................... 79x81 Particulate Matter in Snow and Ice..................................................... 82-84 Icebergs: Types and Sediment Content.............................................. 84...85 Deployment of Drifting Meteorological Buoys................................... 85-86 A "Fishermans Camp"............................................................................ 86-88 Hydrography.................................................................................................. 89 Secchi Depth Measurements................................................................ 89-90 Evidence for Hydrothermal Activity. Gakkel Ridge........................... 90r.93 Bathymetry .............................................................................................. 94-99 Sediment Distributions........................................................................... 1.00 Parasound-Data.................................................................................. .1.QQ:1.1.0 Sediment Cores.................................................................................................. 111-115 Sediment Geochemistry.................................................................... 1-16:1.1.7 Petrogenesis of Crustal Rocks 118 Introduction........................................................................................................... 118-120 Planning arid Operations 120-128 Samples 129-132 ~bservations 132-141 Di~cussion............................................................................................................. 142-162 Conclusions......................................................................................................... 162- 1 64 . Geophysical Investigations................................................................... 1.65 Introduction.......................................................................................................... 165-169 Seismic Reflection Experiments...................................................... 1.6.9y.1.73 Refraction Experiments along Seismic Reflection Transects.. 174-1.77 Seismic Refraction Experiment along the Gakkel Ridge ............1.78-1.80 Gravimetric Measurements....................................................................... 1.81 Helicopter Based Magnetic............................................................... 181.:1.85 Heat Flow Measurements................................................................................ 186-190 Seismological Studies .......................................................................................191-201 Magnetotellurics on Drifting Ice Floes............................................ 201.206 Plans for Future Werk ....................................................................................207-2 10 Public Relations................................................................................ 21.7.21.3 Appendices Contents Appendices................................................................................. 2.23 1. Scientific Party ARK XVIIl2 ............................................................... 2.24:225 2. Participating Institutions ARK XVIIl2 .............................................. 22.6227 3. Ship's Crew ARK XVIIl2 .................................................................... 22.8-2.29 4.* Scientific Party on HEALY ........................................................................ 2.30 5. Station Log POLAl3STERN............................................................................. 231 -234 Station Log HEALY............................................................................. 2-3-5240 Petrology: Sampling Technologies.................................................. 241.245 Petrology: Sample Descriptions....................................................... 24628.1. Thin Sections Overview ..................................................................... 2822.88 Thin Section Descriptions ................................................................. 289-335 MAPR.................................................................................................................... 336-341 TV-Grab Video ............................................................................................. 342 OFOS Observations ..........................................................................................343 Sediment Core Descriptions............................................................. 344-350 Geophysical Investigations: Experience Report .......................... 351.-387 Polar University............................................................................................ 388 List of Abbreviations and Acronyms ...............................................38.9-390 Karasik Seamount ..............................................................................................391 -397 * only on CD AMORE 2001 : Executive Summary The AMORE 2001 (Arctic Mid-Ocean Ridge) expedition to the central Eastern Arctic Ocean combined the operations of 2 research ice-breakers to make cer- tain investigations possible at all, to improve Progress, efficiency and safety in the ice. The main target area was the ridge crest of the western Gakkel Ridge. Traverses from the north-eastern Barents Sea shelf to the Gakkel Ridge and from to the Lomonosov Ridge were used for continuous seismic reflection pro- files across the Nansen and Amundsen basins. The two ships operated in tandem for geophysics operations, and were able to either work together or to separate for sampling operations. Sampling was to be conducted via dredge, TV-grab, gravity and rock cores from both shipS. At sea observations include hand sample descriptions of all rock types encountered, preliminary geochemistry (carried out on HEALY) and thin section analyses (carried out on POLARSTERN). HEALY and POLARSTERN reached the North Pole on September 6, 2001. On August 23 a historic meeting of 3 research ice-breakers occurred on top of the Gakkel Ridge. More than 250 Crew and scientists from 17 nations On HEALY, the Swedish ODEN and POLARSTERN exchanged data and samples; the gathering On the ice comprised more scientists than ever had met at the Same time and place in the central Arctic Ocean. 00th ships succeeded in charting by multiswath sounding systems SEABEAM on HEALY, HYDROSWEEP on POLARSTERN) 33 000 Square kilometres of the Arctic Ocean floor, mostly of the Gakkel Ridge, including its shallowest (566 m) and deepest (5670 m) points, with unprecedented precision and detail. Multichannel seismic reflection profiles have been shot continuously along the transit trips across the Nansen and Amundsen basins, as well as up to 30 NM long Segments along the Gakkel Ridge, interspersed with rock sampling opera- tions, A substantial number of heat flow measurements has been conducted along the return trip from Lomonosov to Gakkel Ridge and along its ridge crest 1 rift valley. The values increase towards the active Gakkel Ridge in general, but the stations from the rift valley are highly variable. Both ships carried 2 helicopters each, for logistic and scientific purposes. PO- LARSTERN succeeded to deploy routinely helicopters for airborne investiga- tions: HELI-MAG-surveys of the magnetic anomalies of various ridge Segments, deployment of long-term geophysical stations On the ice, beside cargo and per- sonne1 transport between the two ships and ice reconnaissance. Systematic sampling of crustal rocks from the Gakkel Ridge has been carried out for petrological studies,