Litostratigrafi och paleomiljöutveckling i Langelandselv-området, Jameson Land, östra Grönland

Summary: This sedimentological study was carried out within Theme B of the ESF associated programme PONAM (Polar North Atlantic Margins - Late Cenozoic Evolution). This part of the programme is focused on the glaciation history during the last interglacial-glacial cycle in the Scoresby Sund area, East Greenland, and the Svalbard archipelago. The main objective of Theme B is to compare the history of high-latitude glaciation with that at mid latitudes. This is believed to increase the understanding of the dynamic response of different earth systems (atmosphere, oceans, glaciers and biosphere) to the orbital forcing on major climatic changes. The aim of this study was to make a palaeoenvironmental reconstruction for the last interglacial-glacial cycle in a small area on south-western Jameson Land, East Greenland. The reconstruction was based upon a lithostratigraphy for the area, which was established from sedimentological investigations in four sections. The investigated area, the Langelandselv area, is situated on the Scoresby Sund coast of Jameson Land. It is characterized by a thick pile of Quaternary sediments deposited on top of the Jurassic sandstone and shale. Earlier investigations have revealed three stratigraphical units in the area; the Langelandselv interglaciation (Eemian), the Jameson Land marine episode (Early to Mid-Weichselian) and the Flakkerhuk glaciation (Mid- or Late Weichselian). The non-glacial deposits have been described as shallow water marine and deltaic sediments, while the sediments associated with the Flakkerhuk glaciation have been charactcrized as tills. The methods used in the sections, which were cut out in the sides of two of the numerous ravines, were sketch drawing combined with thorough description of sediments and structures, photo documentation, measuring of tectonic elements and palaeocurrents, fabric analysis and sampling for absolute dating, mollusc analysis, lithological analysis and foraminifera analysis. The reconstructed palaeoenvironmental evolution starts with a period of transgression, followed by a glaciation of the area. This glacial phase was followed by a period of regression, according to the sedimentological evidence in the investigated sections. During the initial transgression, sublittoral or/and braided river sediments were deposited together with deltaic sediments. The glacial phase resulted in deposition of tills and glacio-marine sediments in the area. The subsequent regression caused deposition of shallow water marine sediments and solifluction of the earlier deposited sediments. This palaeoenvironmental evolution is in essence consistent with the earlier presented stratigraphy for the area. The transgressive phase might correspond to the Langelandselv interglaciation and the Jameson Land marine episode. The glacial phase may be correlated with the Flakkerhuk glaciation, and the subsequent regressional phase might correspond to the Holocene regression of the area. Since the absolute dating of samples from the sections has still not been carried out, it is presently impossible to draw any further conclusions about the timing of the events