Possible retrogressive flow slide deposits from the Kongsfjord Formation: a Precambrian submarine fan, Finnmark, N. Norway

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ABSTRACT

Three thinning and fining-upward turbidite sequences are described from the Precambrian Kongsfjord Formation, a 3.5 km thick flysch succession. Their thicknesses range between about 2 and 5 m. They show a progressive upward decrease in bed thickness, bulk mean grain size and the ratio of the higher to lower energy division of the Bouma sequence. In one case, however, there is an initial upward bed thickness and grain size increase, with an increase in the proportion of the higher energy division. The absence of structureless mud of the Bouma E division and the presence of wavy interfaces between beds, together with similar palaeo-currents within each sequence suggest that these sequences resulted from related depositional events. These sequences are interpreted as the deposits of retrogressive flow slides, as an alternative to the classic mechanism of channel fill after abandonment.

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