Open AccessUpper Cenozoic sequences in the southeastern North Sea Basin
Author(s) -
Jan C. Sørensen,
Olaf Michelsen
Publication year - 1995
Publication title -
bulletin of the geological society of denmark
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.674
H-Index - 28
eISSN - 2245-7070
pISSN - 0011-6297
DOI - 10.37570/bgsd-1995-42-08
Subject(s) - progradation , geology , cenozoic , unconformity , paleontology , marine transgression , structural basin , sedimentary depositional environment , fluvial , erosion , geomorphology
The Upper Cenozoic deposits, which cover the "mid-Miocene unconformity" in thesoutheastern North Sea Basin are subdivided into thirty-one sequences. Progradation fromthe east to the west is observed. The lowstand systems tracts appear seismically asprograding wedges. The top lowstand surface is recognized as a toplap surface in areaswhere high-angle progradation dominates the stratal pattern, indicating the presence of abypass zone formed during lowstand progradation. The maximum flooding surface isidentified on logs as a maximum gamma ray peak, which separates an upward fining froman upward coarsening trend. The two trends represent the transgressive and the highstandsystems tracts, respectively.Sequence boundaries are commonly associated with widespread erosion. The presenceof both fluvial and submarine erosion is interpreted on the basis of the orientation ofincision and the position of erosion relative to the depositional shoreline break of thepreceding sequence.In Late Miocene times the Ringkøbing-Fyn High partly separated the southeastern NorthSea into two embayments, which were connected by a deep seaway towards the west.Sediment accumulation rates seem to have culminated during periods with decreasingpalaeo-temperatures. During relatively cold periods, the sequences were deposited as prograding wedges with a limited lateral extent. Two periods with maximum palaeotemperatures are time-equivalent with the two most distinct maximum flooding surfacesand intervals characterized by low sediment accumulation rates.