Sedimentologisk och morfologisk undersökning av Gyllebo-Baskemöllafältet, östra Skåne

Summary: Gyllebo-Baskemöllafältet is situated in eastern Skåne, some kilometers north of Simrishamn (fig. 1). It is an area consisting mostly of glaciofluvial and glaciolacustrine sediments. The area is surrounded by till (fig 2). Most of the previous investigations in the area concern the glaciolacustrine deposits around Rörum, while this investigation mainly deal with the glaciofluvial deposits. The purpose of this investigation is to make a morphologic interpretation and dividing of Gyllebo-Baskeöllafältet into subareas and to reconstruct the sedimentation processes and the sedimentary environment that prevailed when a central plateau area was formed. Aireal photos, maps, information concerning boreholes and field studies have been used to study the morphology. Sections in two gravelpits, Sofielust and Örnaberga, in the central plateau area were documented. Description of sediment and structures were combined with drawing of sketches. Samples were collected for analysis of particle size, particle shape and roundness, maximum particle size and petrographical composition. Paleocurrent measurements and fabric analysis have also been made. Gyllebo-Baskemöllafältet has been divided into five subareas based on differences in morphology, topography, thickness of the deposits and type of sediment (fig. 2). Subarea 1 has glaciolacustrine sediment and is the lowest lying subarea. Subarea 2 is the central glaciofluvial plateau area. Subarea 3 lies on an elevation in the bed rock and has a thin cover of till. Subarea 4 has glaciofluvial sediment strongly influenced by stagnant ice. Subarea 5 is also a glaciofluvial subarea. It has a undulating surface with hills in a northwest-southeast trending direction. The sediments at the Sofielust gravelpit are interpreted as sediment deposited in a subaqueous fan. Several fans might have overlapped to form the plateau. At Örnaberga the sediments are interpreted as esker sediments, deposited in an open channel in stagnant ice. Thus the sedimentation took place close to the icemargin. The wide extension of the formation shows that the draining system must have been complex. Gyllebo-Baskemöllafältet was formed as the glacier retreated towards northeast. The glaciofluvial deposits were deposited close to the icemargin in a local ice-dammed lake, that reached 85 m.a.s.l. when the central plateau area was formed. The glaciolacustrine deposits were deposited in front of the icemargin but more distal to the tunnel mouth.