Entwicklung von Sedimentbecken
Final Report Abstract
The geological paradox of at least three Neoproterozoic glaciomarine diamictite intervals intercalated within apparently warm-water carbonates at tropical latitudes during the Neoproterozoic remains an unsolved puzzle. Several conceptual models have been proposed to explain these apparent rapid swings between climatic extremes, termed the Neoproterozoic climatic paradox (NCR), and the associated assumed isotopic changes in seawater chemistry. This paper concentrates on the major environmental change in the aftermath of one of these, the "Marinoan" interval in northern Namibia. In Oman, postglacial transgressive Infracambrian sedimentary successions represent important hydrocarbon source rocks. Their eventual source rock characteristics in other parts of the world are therefore of special economic interest. The relation of this postglacial sediments of northern Namibia with the underlying cap carbonate and diamictite succession is discussed and a model of the succession of events is presented. The paleotopography, caused possibly by glacial influence but more likely by ongoing tensional activity strongly influenced the petroleum system created and played an important role for the hydrocarbon prospectivity of this postglacial succession. Tensional activity on the shelf of the southern margin of the Congo craton was repeated, and different subbbasins were created before, during and after the "Marinoan" glaciation. The newly formed relief was flooded, and the different subbasins were affected by restricted circulation for quite some time. This general scenario bears many resemblances to the late Ordovician/early Silurian petroleum system, formed during post-glacial sea level rise as well.
Publications
- Spence, G.H., Jäger, H., Bechstädt, T., 2006, A sedimentary, isotopic (δ13C, δ18O) and geochemical (TOC, N, S) investigation of a Neoproterozoic negative carbon isotope stage associated with a cap carbonate in the Otavi Mountain Land of Namibia: Significance for the Snowball Earth Model. British Sedimentological Research Group, Annual Meeting, 17th-19th Dec. 2006, Aberdeen, Abstract vol. p. 106.
- T. Bechstädt, G. Spence and G. Werner, 2006, The Southern rifted margin of the Congo Craton (Cryogenian, Late Proterozoic, Northern Namibia): Outcrop analogs of potential hydrocarbon systems. Global Infracambrian Petroleum Systems and the Emerging Potential in North Africa, 29th - 30th November 2006, Burlington House, London, Abstract vol. p. 15-16.
- Seeling, M., Emmerich, A., Bechstädt, T. & Zühlke, R. (2005): Accommodation/sedimentation development and massive early marine cementation: Latemar vs. Concarena (Middle/Upper Triassic, Southern Alps).- Sedimentary Geology, 175, 439-457.
