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70 Summary of results The summit plateaus of the mountain range on Store Koldewey is covered by rocks dominantly of local material weathered to different degrees. On all the summits erratic material is occurring as smaller boulders from which no one was large enough to sample for SED. The erratic material is represented by white, red and purple quartzites. On the edges of the plateau scattered outcrops of bedrock occur. In the U-shaped valleys which intersect the plateau mountains glacial striae were observed, with a direction of c. 70°. On the ice scoured northern part of the island glacial striae have a direction of 96° and 104°. Both the area east of the plateau mountains and the southern lowland are covered by a ground moraine containing of the local gneisses and quartzite boulders. On the ground surface stone rings and other freeze-and-thaw features were observed. On the west coast of the island a series of accentuated moraine ridges were observed an a height of c. 100 m a.s.l. The freshness of these ridges suggests a Holocene age. 6.6 Onshore marine deposits O. Bennike In connection with the lake coring programme carried out during the ARK XIX/4 expedition, the opportunity arose to do some work on the raised marine and littoral deposits in the areas visited. Pre-Holocene deposits were found on Store Koldewey in 1907, but have not been revisited since then, and no Holocene marine deposits had been located on this island. Northeastern Geographical Society Ø was visited by Quaternary geologists more than 30 years ago, but few details from this investigation have been published (Funder & Hjort 1973, Hjort 1979, 1981). Pliocene (?) sediments on Store Koldewey Already in 1907 during the Danmark Ekspedition, shell bearing deposits were found above the Jurassic sediments on Store Koldewey. A few years later the shell fauna was described by the Danish zoologists Adolf Jensen. Eight species could be identified, and the fauna could be characterized as a high arctic fauna similar to that living in the region at the present. All species are extant, and Jensen considered the fauna of Quaternary age. However, the deposit was found at around 120 m a.s.l., much higher than any other shell bearing Quaternary deposit known from East Greenland at that time. In the 1970’s some of the shells were submitted for radiocarbon dating, yielding a non-finite age (>40 000 years BP, Lu-930, Hjort 1981). The Store Koldewey fauna shows some similarity to that from the Pliocene Kap København Formation in North Greenland. However, it was not until 2003 that the chance arose to revisit the Store Koldewey deposits. During the summer it was found that the Pliocene (?) sediments could be followed for about 30 km along the east coast of Store Koldewey. The deposits are everywhere
located above the Mesozoic sediments (Jurassic and Cretaceous), at elevations of 110-130 m a.s.l. The sequence may either have been lifted up by glacio-isostatic rebound, or by tectonic uplift. In this connection it may be mentioned that seven samples of bedrock were collected from Store Koldewey. These samples will be analysed for fission tracks, which may show if the island has been subject to anomalously high uplift rates in the Neogene. The sediments are overlain by till. The Pliocene (?) sediments consists of silt and fine sand with some pebble layers. Water escape structures and other penecontemporaneous deformation structures were seen, these point to a high sedimentation rate. The lack of trace fossils such as burrows in the sediments may be interpreted along the same line. The deposits are often disturbed by solifluction and slumping, and most exposures are only a few meters high, but at one site a higher section could be logged. Shells were collected at a number of sites, but the faunas are remarkably uniform, and similar to the fauna described by Jensen. Among the molluscs, Hiatella arctica and Mya truncata are the dominating species, but the fauna also includes Astarte borealis, Astarte montagui, Portlandia arctica, Portlandia sp., Cyrtodaria kurriana, Macoma calcarea, Macoma baltica, Serripes groenlandica, Clinocardium cilliatum, Nucula sp., Trophon sp., Natica sp. and Buccinum sp.. Surprisingly, the fauna also includes remains of a brachipod, probably an un-described extinct species of Terebratula. What appears to be the same species also occurs in the Kap København Formation and in Pliocene sediments from Ile de France in Northeast Greenland, and this is the main reason for currently suggesting that the sediments on Store Koldewey are of Pliocene age. The brachiopod material from Store Koldewey is much better preserved than earlier collected material from Greenland, and will probably allow us to erect a new species. Overall, the fauna indicates that the sediments were deposited on the inner shelf, at water depths of maybe 10-20 m. Some influence of fresh water is indicated by the occurrence of Cyrtodaria kurrinana. Most of the mollusk species currently live in Northeast Greenland, but at least one of the un-identified species probably represents a southern extra-limital species, pointing to higher sea water temperatures than at present. For dating the sediments, 40 orientated sediment samples have been collected for palaeomagnetic analyses, and bivalve shells have been collected for analyses of Strontium isotopes and aminoacid racemization ratios. Furthermore, samples have been collected for microfossil analyses, and hopefully the results from analyses of foraminifers, dinoflagellate cysts and other microfossils can help to constrain the age of the sediments. In addition, the microfossil results will throw light on palaeoenvironments, such as depositional environments, palaeo-oceanography, palaeotemperatures and former sea-ice cover. At one site poorly preserved small wood pieces were found, and at three sites thin layers rich in washed together plant remains were discovered. From the latter sites we collected samples, which are expected to provide data on the former vegetation and flora of this part of Greenland. 71
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the Expedition ARKTIS-XIX/4 of the
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1 Cruise summary W. Jokat The exped
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6 1.1 Wetterverlauf ARK XIX/4a Bei
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8 noch vor der Küste, fern davon a
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Page 32 and 33: 30 Preliminary results Along profil
Page 34 and 35: 32 In addition to the deep seismic
Page 36 and 37: 34 Fig. 2-5: Flight statistics for
Page 38 and 39: 36 Fig. 3-1: Seafloor topography of
Page 40 and 41: 38 In total, the PARASOUND system o
Page 42 and 43: 40 Figure 4.1-3: Example of PARASOU
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Page 46 and 47: 44 After PCR was finished, samples
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Page 62 and 63: 60 6.3 Diatom phytoplankton and phy
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Page 74 and 75: 72 Pre-Holocene shell material Pre-
Page 76 and 77: 74 Christensen, T.R. (1993): Methan
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