Cambrian platform - outer shelf relationships in the Nordenskiöld Fjord region, central North Greenland

J.R Ineson,J.S Peel

doi:10.34194/rapggu.v133.7972

Abstract

Cambrian sequences around the head of Nordenskiöld Fjord, central North Greenland, preserve the transition from platform interior carbonates of the Ryder Gletscher Group (redefined) to outer shelf-slope and platform margin sequences assigned to the Brønlund Fjord and Tavsens Iskappe Groups. Study of this transition has allowed redefinition and integration of these two stratigraphic schemes. Shallow subtidal to intertidal, well-bedded carbonates of the platform interior grade north-eastwards into high-energy grainstones and algal boundstones of the platform margin complex. Platform foreslope facies show well-developed clinoform bedding and wedge out into dark carbonates and clastics of the outer shelf sequence.

Highlights

Cambrian sequences around the head of Nordenskiold Fjord, central North Greenland, preserve the transition from platform interior carbonates of the Ryder Gletscher Group to outer shelf-slope and platform margin sequences assigned to the Brønlund Fjord and Tavsens Iskappe Groups
Cambrian sediments are widespread in North Greenland, both in the largely undeforrned shelf sequences which tend to outcrop in the southern part of the region, just north of the ice margin, and in the strongly folded deep-water trough sediments forming the northern coast region
Platform carbonates of the Lower Cambrian Portfjeld Formation occur extensively in central and eastern areas. They form the lowest regionally recognised Cambrian unit, sporadicexposures of shales, sandstones and carbonates which collectively can be referred to the Skagen Group of Friderichsen et al (1982) occur at several localities from northern Wulff Land to north-eastern Peary Land beneath the Portfjeld Formation (Peel, 1982; Dawes & Peel, 1984; Higgins & Soper, 1985; Surlyk & Ineson, 1987)

Summary

Jungersen Gletscher

Peel & Wright (1985) had traced the Ryder Gletscher Group as far east as Nordenski6ld Fjord recognising an abrupt, but at that time poorly understood transition into the Brønlund Fjord Group and Tavsens Iskappe Group sequences on the eastern side of the fjord Among other details, they noted a very thick unit of paIe weathering dolomite into which formations of both sequences intergraded. It is recognised that this area marks the transition from shallow water platform sequences of the Ryder Gletscher Group in the west and south-west into the prograding platform margin and outer shelf slope deposits of the Brønlund Fjord and Tavsens Iskappe Groups, to the east and north-east. Ewx: Cl fi: Cass Fjord Cape Wood Cape Kent Wulff River Cape Ingersoll Cape Leiper

Ryder Gletscher Group

Kronprins Christian Land

INNER SHELF SANDSTONES