Wo war die Küste? : Rekonstruktion von kreidezeitlichen Meeresspiegel-Schwankungen

Wo sich während der verschiedenen Erdzeitalter die Küste befand, beeinflusst bis heute die Beschaffenheit des geologischen Untergrundes. Mit Hilfe von geochemischen Analysen an Bohrkernen untersuchen Wissenschaftler des Instituts für Geologie in Zusammenarbeit mit Wissenschaftlern der Bundesanstalt für Geowissenschaften und Rohstoffe die Zusammensetzung der Sedimentgesteine im Untergrund, um damit der Küstenlinie auf die Spur zu kommen. Für die Energiegewinnung oder Endlagerung von hochradioaktiven Abfällen kann dies von großer Bedeutung sein

Using high‐resolution XRF analyses as a sequence stratigraphic tool in a mudstone‐dominated succession (Early Cretaceous, Lower Saxony Basin, Northern Germany)

Delineation of stratigraphic sequences and their component systems tracts in mudstone‐dominated successions is challenging due to the relatively homogenous, fine‐grained nature of the strata. High‐resolution elemental intensity data from X‐ray fluorescence core scanning is used in order to develop a sequence stratigraphic framework for the Lower Cretaceous monotonous mudstone succession in the eastern Lower Saxony Basin. The study is based on four drill cores covering the Berriasian to Aptian interval. In addition, carbon isotope (δ13Corg), grain size and CaCO3 analyses were carried out on discrete samples. The studied cores represent both proximal and distal basinal environments of the eastern Lower Saxony Basin and can be reliably correlated by utilizing variations in selected X‐ray flourescence elemental ratios, K/Ti data have proven to be particularly suitable in this regard. The core correlation shows that chemostratigraphic variability within the studied succession is laterally reproducible in the eastern Lower Saxony Basin, and can be used to establish a sequence stratigraphic framework. Further, Si/Al and Ca/Ti ratios have been applied to characterize the cores in terms of variation in grain size and CaCO3 content, respectively. Vertical grading trends inferred from Si/Al changes were used to identify transgressive and regressive systems tracts within the studied succession. An important regression in the uppermost lower Valanginian coincides with the onset of the Valanginian Weissert Event, as indicated by the well‐known positive δ13C shift, and, thus, supports the idea that the initial interval of this event corresponds to enhanced supply of terrigenous material. The results of this study are also in agreement with previously recognized transgressive–regressive trends in the Lower Saxony Basin and adjacent areas. This clearly shows that systematic geochemical variations recorded in mudstone‐dominated basinal settings are suitable to establish sequence stratigraphic frameworks

Ein neues Querprofil durch die Harzaufrichtungszone östlich Blankenburg: Konsequenzen für Lithologie, Stratigraphie und Tektonik

kein Abstract vorhande

Newfoundland Neogene sediment drifts: transition from the Paleogene greenhouse to the modern icehouse

This workshop brought together specialists from various fields to develop a drilling proposal to fill the "Oligo-Miocene Gap" that exists in our understanding of the functions of Earth's systems. We propose to establish the first continuous high-deposition record of the Oligo-Miocene through new International Ocean Discovery Program (IODP) drilling in the North Atlantic to allow the development of a continuous Neogene cyclostratigraphy and to enhance our knowledge of Oligo-Miocene ocean–ice–climate dynamics. The workshop was held in Heidelberg from 15 to 17 September 2014 funded by ESF (EARTHTIME EU), NSF, and the ECORD MagellanPlus Workshop Series Program. A total of 24 participants from six different countries (Australia, France, Germany, the Netherlands, United Kingdom, and United States) attended the workshop, including several early career stage researchers. We discussed certain aspects of Cenozoic paleoceanography and paleoclimate and how the gaps in the Oligo-Miocene could be filled using scientific drilling. The ultimate goal of the workshop (to submit a pre-proposal to IODP) was achieved (IODP Proposal 874-pre was submitted 1 October 2014). Our workshop consisted of overview presentations followed by self-selected breakout groups that discussed different topics and produced text and figures for the proposal. Here, we give a short overview of the major topics discussed during the workshop and the scientific goals presented in the resulting IODP pre-proposal

Facies Distribution, Sequence Stratigraphy, Chemostratigraphy, and Diagenesis of the Middle-Late Triassic Al Aziziyah Formation, Jifarah Basin, NW Libya

This study presents the depositional facies, sequence stratigraphy, chemostratigraphy and diagenetic evolution of the Middle-Late Triassic Al Aziziyah Formation, Jifarah Basin northwest Libya. Eight measured sections were sampled and analyzed. High-resolution stable carbon isotope data were integrated with an outcrop-based sequence stratigraphic framework, to build the stratigraphic correlation, and to provide better age control of the Al Aziziyah Formation using thin section petrography, cathodoluminescence (CL) microscopy, stable isotope, and trace element analyses. The Al Aziziyah Formation was deposited on a gently sloping carbonate ramp and consists of gray limestone, dolomite, and dolomitic limestone interbedded with rare shale. The Al Aziziyah Formation is predominantly a 2nd-order sequence (5-20 m.y. duration), with shallow marine sandstone and peritidal carbonate facies restricted to southernmost sections. Seven 3rd-order sequences were identified (S1-S7) within the type section. North of the Ghryan Dome section are three mainly subtidal sequences (S8-S10) that do not correlate to the south. Shallowing upward trends define 4th-5th order parasequences, but correlating these parasequences between sections is difficult due to unconformities. The carbon isotope correlation between the Ghryan Dome and Kaf Bates sections indicates five units of δ13C depletion and enrichment (sequences 3-7). The enrichment of δ13C values in certain intervals most likely reflects local withdrawal of 12C from the ocean due to increased productivity, as indicated by the deposition of organic-rich sediment, and/or whole rock sediment composed of calcite admixed with aragonite. The depletion of δ13C is clearly associated with exposure surfaces and with shallow carbonate facies. Heavier δ18O values are related to evaporetic enrichment of 18O, whereas depletion of δ18O is related to diagenesis due to freshwater input. Al Aziziyah Formation diagenetic events indicate: 1) initial meteoric and shallow burial; 2) three types of dolomite D1, D2 and D3 were most likely formed by microbial, seepage reflux and burial processes, respectively; and 3) diagenetic cements cannot be related to the arid, mega-monsoonal climate of the Triassic and most likely formed subsequently in a humid, meteoric setting

Case studies of Mesozoic calcareous nannofossils

Kalkige Nannofossilien (KN) stellen seit dem Mesozoikum eine wichtige Komponente des marinen Phytoplanktons dar. Sie lassen sich zur Datierung mariner Sedimente und als paläoozeanografische Proxies nutzen. Die Ziele dieser Arbeit sind es, das Verständnis von Wechseln in den KN-Vergesellschaftungen (KNV) und von der Größenvariabilität einzelner Taxa im Hinblick auf vermutete Umweltveränderungen innerhalb verschiedener Zeitskalen zu verbessern. Hierzu wurden zwei Zeitscheiben untersucht. (1) DSDP-Bohrungen im Atlantik wurden im Hinblick auf Langzeit-Schwankungen (mehrere Mio. J.) in der Zusammensetzung der KNV während des Jura-Kreide Grenzbereichs bearbeitet. Außerdem wurde die Größenvariabilität von einigen KN-Taxa und der Anteil von KN an der pelagischen Sedimentation untersucht. (2) Paläoozeanografische Veränderungen auf Milankovitch-Zeitskalen (18-100 kJ) wurden für das "OAE 1d" (Alb) in SE Frankreich rekonstruiert und deren möglicher Einfluss auf die Morphologie der KN untersucht.Calcareous nannofossils (CN) are an important component of the marine phytoplankton since the Mesozoic. For the fossil record they serve as accurate stratigraphic markers and palaeoceanographic proxies. The overall objectives of this thesis are to improve our understanding of changes within the assemblages of CN and their morphological variability with respect to palaeoenvironmental changes on different timescales. In order to achieve this two time slices have been studied. (1) Long-term changes (several million years) in the CN assemblage have been investigated from DSDP sites in the Atlantic across the Jurassic-Cretaceous boundary. Furthermore, the morphology of common taxa and the contribution of CN to the pelagic sedimentation have been studied. (2) Short-term palaeoceanographic changes on the scale of Milankovitch cycles (18-100 kyr) have been reconstructed for the "OAE 1d" (Albian) in SE France and their possible influence on the morphology of CN has been evaluated

Changes in the pelagic carbonate production across the Jurassic/Cretaceous boundary

Bornemann André, Mutterlose Jörg. Changes in the pelagic carbonate production across the Jurassic/Cretaceous boundary. In: Documents des Laboratoires de Géologie, Lyon, n°156, 2002. STRATI 2002. 3ème congrès français de stratigraphie. Lyon, 8-10 juillet 2002. p. 56