Abstract
The early structural evolution of the embayment is evaluated by interpretation of sedimentary features at the contact between Precambrian basement and the overlying sediments and by interpreting vertical facies relationships within the Cretaceous sediments.
Highlights
In the Nugssuaq embayment the unconformity between the Precambrian basement rocks and the Mesozoic cover is exposed only in a few localities
Additional difficulties are introduced by a number of young coast parallel fauIts; generally they are normal slip fauIts, but there is at least one possibie major oblique slip fauIt present
At the time of the field investigations from 1972 to 1974 the biostratigraphic position of the sediments was based on Koch (1964), who assumed an unconformity between the Lower Cretaceous Korne Formation and the younger Atane Formation
Summary
A second haly silty band again around 30 cm thick overlies the more massive 'granite wash' bed It is followed upwards by fine flaggy andstones, rich in dispersed organic debris and with concentralion of mica and coaly matter on the partings. The lack of clay sized weathering products can either be ascribed to gentle winnowing or may be related to chemical conditions The absence of both ferric and ferrous colorations below the first concentration of organic matter in the carbonaceous siltstone band would indicate acid environment in which most mica minerals are unstable (Fuchtbauer & Muller, 1970). Upwards the development of lenticular bedded siltstone and thinly bedded, flaggy, medium grained sandstone indicates continuous shallow water environment; the intercalations of coarser sands could be produced by catastrophic pulses like storms or floods providing increased influx of materiaL That deposition of the 'granite wash' was quick is indicated by the slight loading produced in the upper laminated fine sandstone. A prograding shore environment, either marine or lacustrine, might be considered
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