Evaluation and modelling of Tertiary source rocks in the central Arctic Ocean     

Ute Mann  Jochen Knies  Shyam Chand  Wilfried Jokat  Ruediger Stein  Janine Zweigel   《Marine and Petroleum Geology》2009,26(8):1624-1639

With the recently recovered organic-rich sediments of early Tertiary age from the Lomonosov Ridge by the Integrated Ocean Drilling Program (IODP) Expedition 302, the first data collection directly from source rocks of the central basins of the Arctic Ocean is now available. Using the results of seismic interpretations and published sedimentological and organic geochemical data from Expedition 302, the framework for the first quantitative assessment of source-rock quality and distribution of the Palaeogene sediments was modelled in the central Arctic Ocean. The modelling results suggest that an approximately 100-m-thick Early to Middle Eocene sedimentary sequence of good to very good source rocks exists along a 75 km long transect across the Lomonosov Ridge. In-situ generation of hydrocarbons is unlikely because the overburden (200–250 m) and consequently the thermal maturity are too low. Burial history and thermal modelling reveal that an additional overburden of at least 1000 m is necessary to start hydrocarbon generation along the ridge. However, source-rock modelling results show that good source-rock potential may exist in correlative units in the adjacent Amundsen Basin. Simulated organic carbon contents of 1.5–5%, coupled with an overburden of 1000–1200 m, and heat flow anomalies (117 and 100 mW m⁻²) due to the vicinity to the Gakkel Ridge spreading centre indicate that necessary conditions for hydrocarbon expulsion are already reached, and point to viability of a potential petroleum system. Our results support the hypothesis that deposition of a potentially good hydrocarbon source rock occurred across the entire Arctic Basin and adjacent margins during the early Tertiary.  相似文献   

Variography of submarine morphology: Problems of deregularization, and cartographical implications     

Ute Christina Herzfeld 《Mathematical Geology》1989,21(7):693-713

During the German Antarctic Expedition VI (leg 3, December 1987 to March 1988), bathymetric surveys were made in the Weddell Sea by the SEABEAM sonar system. For the first time geostatistical methods were applied in the SEABEAM-postprocessing. The investigations of variography that were necessary prior to the cartographical-geomorphological evaluation shed new light on classical geostatistical concerns. SEABEAM data provide a good example of a mean square, differentiable regionalized variable, where data are sampled over a two-dimensional support due to the technique of the sonar device. By deregularizations of the sample variograms, spatial continuity can be shown to be a property of seafloor depth as well as a point variable. The results are discussed in a sedimentological context. As an application of the regional variogram analyses, large-scale kriged bathymetric maps are presented.  相似文献   

Seismic hazard evaluation for dams in northern Colorado, U.S.A.     

Ute R. Vetter  Jon P. Ake  Roland C. Laforge 《Natural Hazards》1996,14(2-3):227-240

A seismic hazard evaluation for three dams in the Rocky Mountains of northern Colorado is based on a study of the historical seismicity. To model earthquake occurrence as a random process utilizing a maximum likelihood method, the catalog must exhibit random space-time characteristics. This was achieved using a declustering procedure and correction for completeness of recording. On the basis of the resulting a- and b-values, probabilistic epicentral distances for a 2 × 10^–5 annual probability were calculated. For a random earthquake of magnitude M _L 6.0–6.5, this distance is 15 km. Suggested ground motion parameters were estimated using a probabilistic seismic hazard analysis. Critical peak horizontal accelerations at the dams are 0.22g if median values are assumed and 0.39g if variable attenuation and seismicity rates are taken into account. For structural analysis of the dams, synthetic acceleration time series were calculated to match the empirical response spectra. In addition, existing horizontal strong motion records from two Mammoth Lakes, California earthquakes were selected and scaled to fit the target horizontal acceleration response spectra.  相似文献   

    

Ute Christina Herzfeld 《Mathematical Geology》1996,28(2):137-160

In 1963, Gandin published a monograph on optimum interpolation for the objective analysis of meteorological fields, ≓ a method that is similar mathematically to geodetical least-squares prediction and collocation, simple kriging, and spectral interpolation. The common problem is the interpolation or extrapolation or estimation of a continuous spatial property from finitely many observations. Gandin 's method is presented in an inverse-theoretical context with focus on a methodological comparison with related methods. Underlying mathematical assumptions as well as geological implications are discussed. An introductory overview of inverse methods in the earth sciences is given, with emphasis on methods with a structure analysis step.  相似文献   

A magnetotelluric study of the Damara Belt in Namibia: 2. MT phases over 90° reveal the internal structure of the Waterberg Fault/Omaruru Lineament     

Ute Weckmann  Oliver RitterVolker Haak 《Physics of the Earth and Planetary Interiors》2003,138(2):91-112

Magnetotelluric (MT) observations at some sites in the vicinity of the Waterberg Fault/Omaruru Lineament (WF/OL), a major tectono-stratigraphic zone boundary in the Central Zone of the Damara Belt, show evidence for strong three-dimensional (3D) effects. We observe very high skew values, phases over 90°, and a strong correlation of parallel components of the electric and magnetic fields at long periods. Because of the dense site spacing and good spatial coverage, we can positively attribute these effects to local geology and are able to resolve structural detail within the WF/OL. Mapping LaTorraca’s electric characteristic vectors in form of ellipses proved particularly useful in identifying key elements of the conductivity structure for subsequent modelling. 3D and 2D anisotropic modelling can reproduce most of the observed 3D effects. The conductivity anomalies revealed in the area are: (i) a conductive ring structure in the shallow crust along the northern part of the profile; (ii) an anisotropic region in the upper crust with high conductivity parallel to the WF/OL; (iii) anisotropy in the lower crust with a different but undetermined strike direction; and (iv) a shallow elongated conductor sub-normal to the WF/OL. Modelling studies further suggest that the (anisotropic) fault zone is approximately 10 km wide and may reach down to a depth of 14 km or more.  相似文献   

The Baltic Sea Experiment BALTEX: A brief overview and some selected results of the authors     

Ehrhard Raschke  Ute Karstens  Ralph Nolte-Holube  Rüdiger Brandt  Hans-Jörg Isemer  Dag Lohmann  Manfred Lobmeyr  Burkhardt Rockel  Rolf Stuhlmann 《Surveys in Geophysics》1998,19(1):1-22

The mechanisms responsible for the transfer of energy and water within the climate system are under worldwide investigation within the framework of the Global Energy and Water Cycle Experiment (GEWEX) to improve the predictability of natural and man-made climate changes at short and long ranges and their impact on water resources. Five continental-scale experiments have been established within GEWEX to enable a more complete coupling between atmospheric and hydrological models. One of them is the Baltic Sea Experiment (BALTEX).In this paper, the goals and structure of BALTEX are outlined. A short overview of measuring and modelling strategies is given. Atmospheric and hydrological model results of the authors only are presented. These include also the validation of precipitation using station measurements as well as validation of modelled cloud cover with cloud estimates from satellite data. Furthermore, results of a large-scale grid based hydrological model to be coupled to atmospheric models are presented.This research has never been possible without the contribution of research groups and operational institutions from all 10 member countries. We concentrate here on results obtained at the GKSS research center.  相似文献   

    

Patrick Armstrong  Ute Wardenga 《GeoJournal》1998,44(2):175

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