74 Shelf sand banks and sand dune fieIds from the Volgian-Valanginian Raukelv Formation of Jameson Land, Bast Greenland Finn Surlyk and Nanna Noe-Nygaard

The aims of the present study were: to interpret pre­ Cross-strata mayaiso show glauconite impregnation. cisely the depositional environment of the coarse­ Transport direction was towards the east. A diverse grained, cross-bedded sandstones of the Raukelv For­ marine fauna of bivalves, ammonites and crinoids char­ mation (Lower Volgian - Valanginian) of Jameson acterizes the facies. The giant-scale cross-beds are sep­ Land; to explain the upwards transition over a few arated by sheets of tabular to trough cross-bedded co­ metres from the underlying deep-shelf mudstones and sets 5-10 m thick. These units ean also be followed turbiditic sandstones ofthe Hareelv Formation; to make laterally over tens of kilometres and the top of the precise correlations and comparison with the Hartz co-sets is burrowed and impregnated with glauconite. Fjeld Formation of Milne Land to suggest an alternative They contain marine faunas showing high density and to the fan delta interpretation of Sykes & Brand (1976) diversity. Transport direction was towards the south or, which was proved inadequate by Birkelund et al. (1984); in rare cases, to the north. A few levels of bioturbated and finally to place the Raukelv Formation better within muddy siltstones occur between the coarse-structured the regional tectonic and provenance frarnework. sandstone sheets. The Raukelv Formation was erected by Surlyk et al. Deposition of the Raukelv Formation took place in a (1973) for a sequence up to 300 m thick of very coarse­ system of eastwards migrating sand banks. Bank con­ grained, cross-bedded sandstones of Early Volgian to struction was followed by mainly southwards migration Valanginian age. The formation crops out in southern of sand dune fields. The water depth was below fair Jameson Land where it forms the youngest preserved weather wave base and rate of deposition was slow, unit. Further details on lithology and biostratigraphy reflected by the glauconitized omission surfaces separat­ are given by Surlyk (1973, 1975) and Surlyk & Zak­ ing the sand sheets. harov (1982). The marine nature of the formation was The interpretation of the Raukelv Formation as -rep­ clearly recognized and the bulk of the sequence was resenting sand banks and sand dune fields formed in a interpreted in terms of a marine shelf sandwave system, relatively deep water shelf environment allows a total while a fan delta interpretation was suggested for the reinterpretation of the correlative lower Hartz Fjeld giant-scale cross-beds (Surlyk, 1975; Surlyk et al. 1981). Formation in Milne Land, and of isolated sets of giant­ A pure fan delta interpretation was presented by Sykes scale cross-sets occurring in other Jurassic formations in & Brand (1976) for the lower Hartz Fjeld Formation, a East Greenland. Finally, the upwards transition over a lateral correlative occurring in Milne Land. The latter few metres from the deep-shelf mudstones and turbid­ authors based their essentiaIly subaerial environment itic sandstones of the underlying Hareelv Formation to interpretation on the occurrence of abundant roodets the Raukelv Formation does not require a sea-level extending downwards from the top surfaee of large to drop of several hundred metres as would have been the giant-scale cross-beds. This interpretation was later case if the latter formation was of fan delta or very questioned by Birkelund et al. (1984) who demonstrated shallow marine origin. that the alleged roodets were actually long vertical D­ burrows Diplocraterion habichi of clear marine affinity. Acknowledgements. This study was undertaken while Surlyk They furthermore stressed the abundance of marine was recipient of a research professorship awarded by the Dan­ invertebrate fossils occurring in the Hartz Fjeld sand­ ish Natural Science Research CounciJ. stones. The coarse-grained sandstones of the Raukelv For­ References mation show spectacular examples of large and giant­ Birkelund, T., Callomon, J. H. & Fiirsich, F. T. 1984: The scale cross-bedding. The giant-scale cross-beds occur as stratigraphy of the Upper Jurassic and Lower Cretaceous single isolated sets 15-50 m thick, which ean be followed sediments of Milne Land, central East Greenland. Bul/. over tens of kilometres. The cross-strata are sigmoidal Grønlands geol. Unders. 147, 1-56. and simple or compound, being internally composed of Surlyk, F. 1973: The Jurassic-Cretaceous boundary in Jameson large-scale trough-shaped cross-beds. The set tops are Land, East Greenland. In Casey, R. & Rawson, P. F. (edit.) glauconitized and burrowed by Diplocraterion habichi. The Boreal Lower Cretaceous. Geol. J. Spec. Iss., 5,81-100.

Rapp. Grønlands geol. Unders. 145, 74-75 (1989) 75

Surlyk, F. 1975: Block faulting and associated marine sedi­ gin. In Ken, J. W. & Ferguson, A. J. (edit.) Geology of the mentation at the Jurassic-Cretaceous boundary, East North Atlantic borderlands. Mern. Can. Soc. Petrol. Geol. 7, Greenland. In Finstad, K. G. & Selley, R. C. (edit.) Jurassic 611---645. northern North Sea symposium 1975 (JNNSS-75). Norwe­ Surlyk, F. & Zakharov, V. A. 1982: Buchiid bivalves from the gian Petroleum Society, JNNSSI7, 1-31. Upper Jurassic and Lower Cretaceous of East Greenland. Surlyk, F., Callomon, J. H., Bromley, R. G. & Birkelund, T. Palaeontology 25, 727-753. 1973: Stratigraphy of the Jurassic - Lower Cretaceous sedi­ Sykes, R. M. & Brand, R. P. 1976: Fan-delta sedimentation: ments of Jameson Land and Scoresby Land, East Green­ an example from the late Jurassic - early Cretaceous of land. Bul!. Grønlands geol. Unders. 105,1-76. Milne Land, central East Greenland. Geologie en Mijnbouw Surlyk, F., Clemmensen, L. B. & Larsen, H. C. 1981: Post­ SS, 195-203. Paleozoic evolution of the East Greenland continental mar-

F. S., N. N.-N., Grønlands Geologiske Undersøgelse, lnst. for Historisk Geologi og Palæontologi, øster Voldgade 10, øster Voldgade 10, DK-1350 København K, DK-1350 København K, Danmark. Danmark.

Sedimentological studies of the Upper Triassic to Lower Jurassic succession in the Jameson Land Basin, central East Greenland Gregers Dam

Sedimentological studies of the Upper Triassic to Geological setting Lower Jurassic succession in central East Greenland were initiated in 1987 as a three-year research fellow­ The sediments of the Kap Stewart and Neill Klinter ship programme supported by British Petroleum Devel­ Formations were laid down in the Jameson Land Basin opment, London (Dam, 1988). The study is primarilya in central East Greenland, where they constitute the lithofacies analysis, but ichnology, palynology source­ lowermost two formations ofthe Jameson Land Group rock analysis, porosity/permeability analysis and diag­ (Surlyk et al., 1973). In age the formations span most of enetic studies are also included in the programme. The the Rhaetian-Toarcian interval. Their setting in the Ja­ stratigraphic interval includes the Kap Stewart and Neill meson Land basin was reviewed by Dam (1988). Klinter Formations which have many features in com­ mon with stratigraphically equivalent formations in off­ Kap Stewart Formation shore mid- and northem Norway that form some of the Seven facies associations are here recognized in the most important potential petroleum reservoirs in these Kap Stewart Formation: areas. The field work in 1988 was carried out by the author (1) Lacustrine (prodelta) association; (2) Interdistrib­ accompanied by A. Boesen, and lasted for 7 weeks from utary bay association; (3) Longshore directed shoal as­ late June to late August but was impeded in a three­ sociation; (4) Beach face association; (5) Distributary week period by bad weather in the region. channel association; (6) Interdistributary area associ­ The 1988 activities were concentrated in three main ation; (7) Delta abandonment association. areas; along the west coast of Hurry Inlet, in Lep­ idopteriselv and Liaselv just west of Carlsberg Fjord, Vertical and lateral distributions of environments. and in Ranunkeldal, a tributary valley to Schuchert Dal Along Hurry Inlet in the southeastem part of the basin (fig. 1). Sedimentological studies involved detailed lith­ the Kap Stewart Formation is approximately 200 m ofacies and ichnofacies analyses as well as sampling for thick. In this area Harris (1937) subdivided the forma­ palynofacies analyses, source rock analyses and reser­ tion into an upper 'plant-bearing-series' and a lower voir rock properties. 'barren sandstone'. Although this division has not been adopted in recent literature (Surlyk et al., 1973; Pe-

Rapp. Grønlands geol. Unders. 145, 75-79 (1989)