Abstract This paper presents the results of a study that assesses a new non-taxonomic biostratigraphical technique as a tool for refining reservoir correlations. In this example from the Paleocene Maureen Formation, Fleming Field, UKCS, morphostratigraphy provides greater biostratigraphical resolution than a more conventional biozonation or bioevent approach and significantly improves reservoir correlation. As a result, a different reservoir sand connectivity model is proposed. This model explains production anomalies experienced in the field. The study also clearly demonstrates the applicability of morphostratigraphy to refine correlations within deep marine turbidite settings.

Abstract: Transgressive barriers of the embayed Atlantic and Gulf coast are generally similar in overall form, processes, and landward migration in response to relative sea-level rise, but they vary greatly in potential sources and volume of sand supply. Delaware's transgressive barriers vary in thickness from 25 m to less than 5 m; dunes may rise to 20 m above sea level, whereas barrier-spit and inlet sand reach depths of 10–18 m below sea level. Widths vary between 0 m at eroding headlands and 4–6 km near tidal delta and spit complexes. A complete Holocene paralic sequence for Delaware includes a basal sand and/or gravel overlain by marsh, lagoon, and barrier lithosomes. Shoreface erosion, as the barrier lithosome moves landward, occurs to an average depth of 10 m, with about 50% of eroded sediment derived from Holocene and Pleistocene lagoonal mud outcrops. Since the suspended material is carried out of the shoreface, its removal requires a re-evaluation of the volumetric model commonly inferred from the Bruun mechanism. Also, the third dimension of longshore transport of coarse material needs to be considered. As transgression continues, the ravinement surface exposes lagoonal sediments, marsh mud, irregularly shaped basal remnants of the Holocene barrier lithosome, or varied Pleistocene strata. These are then blanketed by varying thicknesses of inner-shelf sand. Ultimately, the transgressive barrier and associated paralic environments migrate landward to peak interglacial positions where the entire transgressive record may be preserved. A relatively complete vertical sequence of transgressive coastal lithosomes might also be preserved at the outer edge of the continental shelf at glacial sea-level minima. Thus, the optimal chance for total preservation of a transgressive coastal lithosome sequence lies at the extremes, landward at the peak interglacial when eustatic sea-level rise stops and the coastal lithosome sequences become stranded, and possibly on the outer edge of the shelf as deglaciation begins and there is rapid rate of sea-level rise.

Abstract Large ice fields (>25 km 2) formed over the Tazaghart and Iouzagner plateaus of the High Atlas, Morocco during the Late Pleistocene. The plateau ice fields were drained by large valley glaciers forming a series of moraine assemblages. Four moraine units have been mapped and subdivided on the basis of their morphostratigraphy and the degree of soil weathering. Soil profile development index values indicate that the moraine units are widely separated in time; the oldest moraines are deeply weathered and degraded, whereas soils are absent on the youngest moraines. The highest moraine unit was formed by a small niche glacier that was present as recently as the mid-twentieth century. The Pleistocene glaciers are likely to have been associated with wetter conditions than today and colder air temperatures. Combined with ice in neighbouring areas, such as the Toubkal massif, the SW High Atlas supported some of the largest glaciers in Africa during the Pleistocene. The extent of glaciation, with ice exploiting and breaching drainage divides, has major implications for landscape development. The evolution of the High Atlas has been strongly shaped by glaciation that was closely intertwined with tectonic, fluvial and slope processes.

Abstract Late Pleistocene and Holocene geology of the northeastern Gulf of Mexico shelf offshore Alabama and northwest Florida was investigated using 47 vibracores, foraminiferal and macrofaunal assemblages, and bathymetric data. The morphologic and stratigraphic signatures of the last rise of eustatic sea level were examined along this passive continental margin characterized by low subsidence. Major shelf features include shore-oblique sand ridges, mid-shelf linear shoals, and shelf-edge deltas. Surficial shelf sediments consist of >90% sand, <2.7% mud, and <2% granules and fine in a westerly direction from medium to fine sand. The sharp boundary that separates these two surficial sand types (Apalachicola and Mobile subprovinces) is identified for the first time in this study. Six facies and two erosional surfa ces characterize the shelf stratigraphy. Facies 1 is a Pleistocene soil horizon. This facies is truncated by a major erosional unconformity (Type 1 sequence boundary [SB]) that was created by subaerial exposure during the last sea level lowstand and during the bay ravinement process (flooding surface [FS]) of the ensuing transgression (FS/SB). Fine-grained estuarine deposits (Facies 2, 3, or 4 [lower transgressive systems tract]) overlie the unconformity. Facies 3 or 4 are truncated by a shoreface ravinement diastem (flooding surface) and are overlain by a marine shell-bed (Facies 5; lower shoreface). Facies 5 grades into Facies 6, a quartz sand with open marine foraminifera that re presents a shelf sand sheet Facies 5 and 6 comprise the upper transgressive systems tract, which is up to 5.5 m thick. The mid-shelf is characterized by two long (30-120 km), narrow (<6 km), shore-parallel to subparallel sand shoals that average 4 m thick. North Perdido Shoal is located 15-25 km offshore at the 20-25-m isobath, whereas South Perdido Shoal lies 20-70 km offshorc at approximately the 35-m isobath. Both shoals trend southwest-northeast. The linear shoals are not in situ or degraded barriers (Stubblefield et al., 1984a, b), offshore shelf-ridge (bar) complexes (Tillman and Martinsen, 1984, 1987; Gaynor and Swift, 1988), or lowstand/transgressive incised shoreface deposits (Bergman,1994; WalkerandWiseman,1995) because the sediments that comprise the shoals Jie above the shoreface ravincment diastem, and open marine species dominate the foraminiferal and molluscan assemblages. Although shelf morphology is similar to modern barrier island geo morphology, shelf morphostratigraphy is related to transgressive and post-transgressive processes. Shoal form and orientation are dictated by underlying transgressive topography (escarpments) that was cut into the Pleistocene substrate during the post-glacial transgression. During transgression, erosional shoreface retreat produced a trailing sand sheet that draped the transgressive topography. Consequently, 1) the linear nature of the shoals is derived from their formation along the shoreface (i.e., depositional strike) at lower stands of sea level during an overall transgression; 2) sediment transport from the present shoreline across the shelf appears to have little influence on shoal development; 3) the interplay between relative sea-level changes and sediment supply caused translation of the shoreface profile, thus dictating the position of the linear shoals; and 4) post-transgressive reworking and subaqueous landward migration in response to storm processes are integral parts of shoal evolution.