Abstract
The Jurassic of Store Koldewey comprises a Middle Jurassic succession towards the south and an Upper Jurassic succession towards the north. Both successions onlap crystalline basement and coarse sediments dominate. Three main lithostratigraphical units are recognised: the Pelion Formation, including the Spath Plateau Member, the Payer Dal Formation and the Bernbjerg Formation. Rich marine macrofaunas include Boreal ammonites and the successions are dated as Late Bathonian – Early Callovian and Late Oxfordian – Early Kimmeridgian on the basis of new collections combined with material in earlier collections. Fine-grained horizons and units have been analysed for dinoflagellate cysts and the stratigraphy of the diverse and well-preserved flora has been integrated with the Boreal ammonite stratigraphy. The dinoflagellate floras correlate with contemporaneous floras from Milne Land, Jameson Land and Hold with Hope farther to the south in East Greenland, and with Peary Land in North Greenland and Svalbard towards the north. The Middle Jurassic flora shows local variations in East Greenland whereas the Upper Jurassic flora gradually changes northwards in East Greenland. A Boreal flora occurs in Peary Land and Svalbard. The characteristic and stratigraphically important species Perisseiasphaeridium pannosum and Oligosphaeridium patulum have their northernmost occurrence on Store Koldewey, whereas Taeniophora iunctispina and Adnatosphaeridium sp. extend as far north as Peary Land. Assemblages of dinoflagellate cysts are used to characterise significant regional flooding events and extensive sequence stratigraphic units.
Highlights
The Jurassic of Store Koldewey comprises a Middle Jurassic succession towards the south and an Upper Jurassic succession towards the north
The Jurassic succession of Store Koldewey is divided into the Pelion, Payer Dal and Bernbjerg Formations
The Pelion Formation is dated as Late Bathonian – Early Callovian, in the Middle Jurassic, and the Payer Dal and Bernbjerg Formations are dated as Late Oxfordian – Early Kimmeridgian in the Late Jurassic
Summary
18oW parties from the Geological Survey of Greenland (GGU; since 1995 part of the Geological Survey of Denmark and Greenland) studied the geology of the island as part of regional mapping projects (Stemmerik & Piasecki 1990; Henriksen 1997). The upper part of the exposed succession is of Early to Middle Callovian age and biostratigraphically equivalent to the new Spath Plateau Member on Hold with Hope (Vosgerau et al 2004, this volume) where the same two ammonite zones are recorded This part of the Store Koldewey succession provides dinoflagellate cyst data from an interval that is not so well documented in Jameson Land (Milner & Piasecki 1996). Lower Callovian assemblage is characterised by abundant Chytroeisphaeridia hyalina and Pareodinia pachyceras, together with many species not present below e.g. Pareodinia stegasta, Aldorfia aldorfiense and Paraevansia brachythelis. The dinoflagellate cyst assemblage of the lower part of the succession (Bathonian) correlates with assemblages of the A. arcticus – A. cranocephaloide Chronozones from both Milne Land (Assemblages 2 and 3 in: Larsen et al 2003) and Jameson Land (Milner & Piasecki 1996) in central East Greenland. The assemblages in the Charcot Bugt Formation (Assemblages 4 and 5 in: Larsen et al 2003) are not precisely dated but are not older than the A. cranocephaloide Chronozone (Bathonian) and not younger than the Erymnoceras coronatum Chronozone (top Middle Callovian)
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