Tertiary sedimentary development of the Broad Fourteens area, the Netherlands

The Broad Fourteens Basin is a NW-SE trending Mesozoic structural element t hat was affected by inversion movements during the Late Cretaceous (Subherc ynian Phase) and Early Tertiary (Laramide Phase). Since the overlying Terti ary section of this area is relatively little studied, a multi-disciplinary investigation was initiated using both seismic and well data. The present study is the first phase of that project and deals exclusively with the str atigraphical framework and sedimentary development based on well logs from approximately forty wells. The Tertiary sedimentary section in this area (maximum thickness up to appr oximately 800 m) consists of siliciclastic rocks that generally correlate w ell with the established lithostratigraphical framework of the Netherlands. However, the highly variable thickness of these lithological units, illust rated by isopach maps for all units, reflect the intricate pattern of sea l evel movements, differential vertical movements and the ensuing erosion, th at took place in this tectonically active area. Well P06-02, one of the most complete sections in the center of the area, w as selected for detailed biostratigraphical analysis to support further str atigraphical subdivision and correlation. This yielded information on both the distribution pattern of various lithological units and the influence of large, partly global, events during basin development. It is concluded tha t application of detailed sequence stratigraphy in the study area is very p roblematic and only 2(nd) and some 3(rd) order cycles could be recognized.