Jonathan R Ineson
The stratigraphy and sedimentology of the Brønlund Fjord and Tavsens Iskappe Groups (Cambrian) of Peary Land, eastern North Greenland
Ineson, Jonathan R
Proterozoic and Lower Palaeozoic strata in eastern North Greenland record two contrasting depositional regimes: a cratonic shelf bounded to the north by a deep-water basin. The shelf strata include the BrjSnlund Fjord and Tavsens Iskappe Groups, a carbonate-dominated succession up to 900m thick with an age range from late Early Cambrian to earliest Ordovician. The Brrfnlund Fjord Group is subdivided into eight formations; the Tavsens Iskappe Group comprises seven formations.
Twenty-four lithofacies are recognized and grouped into four associations. Association A consists of glauconitic, phosphoritic skeletal carbonates representing deposition on a sediment-starved, carbonate ramp. Association B comprises dark, argillaceous, nodular carbonates, graded carbonates and carbonate breccia beds representing deposition from suspension, turbidity currents and debris flows in a low-energy, open marine environment; an outer shelf-slope setting is envisaged. Evidence of early-diagenetic, submarine nodular cementation and slope creep processes is abundant. Cross-bedded ooidal grainstones characterize Association C which represents a high-energy, shallow-water environment at a carbonate platform margin. Foreslope facies in this association typically show inclined bedding U 30°) and interdigitate with outer shelf rocks. Facies assigned to Association D are burrowed dolomites, flat-pebble conglomerates, algal laminites and bioturbated, cross-bedded sandstones reflecting deposition in shallow subtidal and intertidal environments on a low-energy, restricted platform.
The vertical and lateral relationships between these associations outline a regressive sedimentation pattern, involving northward progradation of inner shelf, shallow-water facies (AssociationsC, D) over outer shelf facies (Associations A, B) and resulting in progressive exposure of the shelf. Evidence of intermittent platform progradation and discrete episodes of outer shelf instability probably record periods of differential shelf subsidence related to basin development.
|Publication Date||Jan 1, 1985|