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Stratigraphic Interpretation (stratigraphic + interpretation)
Selected AbstractsA NEW DEPOSITIONAL MODEL AND SEQUENCE STRATIGRAPHIC INTERPRETATION FOR THE UPPER JURASSIC ARAB "D" RESERVOIR IN QATARJOURNAL OF PETROLEUM GEOLOGY, Issue 3 2001H. Al-Saad Deposition of the Arab Formation on the Arabian Plate followed a eustatic sea-level high during the Oxfordian that deposited the open-marine shelfal carbonates of the Hanifa and Jubaila Formations. Oolite/peloidal shoals and local coral-algal stromatoporoid banks were subsequently deposited on the platform margin. These acted as barriers and led to the differentiation of intrashelf basins from open-marine (Tethyan) waters to the east. During the subsequent Kimmeridgian lowstand, gypsum wedges were laid down in the intrashelf basins. Slight changes in water depth, which exposed or flooded these barriers, are believed to be responsible for the cyclic nature of the Arab Formation sediments. Arab Formation cycles show a 4,h order frequency but have thicknesses more typical of 3rd order Vail-type sequences. This is probably explained by the 4th order flooding events merely topping-up pre-existing accommodation space of tens of metres water depth in the intrashelf basin. Diagenesis associated with movement of hypersaline brines may have been responsible for the development of widespread dissolution porosity and dolomitization. The laminated, organic-rich, bituminous lime mudstones of the Hanifa/Jubaila Formations are the probable source of oil in the Arab Formation in Qatar. The main reservoir types are oolitic-peloidal grainstones and dolomitized limestones. [source] Contribution of different kinematic models and a complex Jurassic stratigraphy in the construction of a forward model for the Montagna dei Fiori fault-related fold (Central Apennines, Italy)GEOLOGICAL JOURNAL, Issue 5-6 2010L. Di Francesco Abstract The Montagna dei Fiori has received attention from geologists over the past decades because of both its Jurassic stratigraphy and its complex present-day structure. The latter is the result of multiple phases of deformation, from the Early Jurassic, during the opening of the Tethyan Ocean, to Neogene evolution of the Apennines fold-and-thrust belt. In this paper, we present a new stratigraphic interpretation of the Jurassic palaeogeography, based on a new geological mapping project in the area. Using this new stratigraphy, we constructed two forward models, using a combination of different fault/fold interactions, in order to unravel the kinematic evolution of the Montagna dei Fiori fault-related fold. The first model was constructed manually using the fault-bend and fault-propagation theories from an initial configuration which included previous extensional features, whereas the second model was constructed using the software 2DMove (Midland Valley) using the fault-bend and trishear fault-propagation folding theories and starting from a layer-cake stratigraphy. Both forward models involved the same main steps and provided a reasonable geological simulation of the geometry of the Montagna dei Fiori structure. Copyright © 2010 John Wiley & Sons, Ltd. [source] Ground penetrating radar survey and stratigraphic interpretation of the Plan du Lac rock glaciers, Vanoise Massif, northern French AlpsPERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2008Sébastien Monnier Abstract Internal boundaries of the Plan du Lac rock glaciers in the northern French Alps were investigated using ground-penetrating radar (GPR) and were correlated with the surface morphology. Data collected using 50,MHz antennae along three profiles were processed in a novel manner by applying modulated automatic gain control to discriminate reflection events according to coherence and continuity patterns. Based on the GPR and morphological analyses, the stratigraphy appears complex, with prominent internal boundaries dividing the features into several depositional units, interpreted as sequential creeping or thrusting events. Copyright © 2008 John Wiley & Sons, Ltd. [source] Trajectory analysis: concepts and applicationsBASIN RESEARCH, Issue 5 2009W. Helland-Hansen ABSTRACT Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these trajectories provides a simple descriptive tool that complements and extends conventional sequence stratigraphic methods and models. Trajectory analysis offers four advantages over a sequence stratigraphic interpretation based on systems tracts: (1) each genetically related advance or retreat of a shoreline or shelf edge is viewed in the context of a continuously evolving depositional system, rather than as several discrete systems tracts; (2) subtle changes in depositional response (e.g. within systems tracts) can be identified and honoured; (3) trajectory analysis does not anticipate the succession of depositional events implied by systems-tract models; and (4) the descriptive emphasis of trajectory analysis does not involve any a priori assumptions about the type or nature of the mechanisms that drive sequence development. These four points allow the level of detail in a trajectory-based interpretation to be directly tailored to the available data, such that the interpretation may be qualitative or quantitative in two or three dimensions. Four classes of shoreline trajectory are recognized: ascending regressive, descending regressive, transgressive and stationary (i.e. nonmigratory). Ascending regressive and high-angle (accretionary) transgressive trajectories are associated with expanded facies belt thicknesses, the absence of laterally extensive erosional surfaces, and relatively high preservation of the shoreline depositional system. In contrast, descending regressive and low-angle (nonaccretionary) transgressive trajectories are associated with foreshortened and/or missing facies belts, the presence of laterally extensive erosional surfaces, and relatively low preservation of the shoreline depositional system. Stationary trajectories record shorelines positioned at a steeply sloping shelf edge, with accompanying bypass of sediment to the basin floor. Shelf-edge trajectories represent larger spatial and temporal scales than shoreline trajectories, and they can be subdivided into ascending, descending and stationary (i.e. nonmigratory) classes. Ascending trajectories are associated with a relatively large number and thickness of shoreline tongues (parasequences), the absence of laterally extensive erosional surfaces on the shelf, and relatively low sediment supply to the basin floor. Descending trajectories are associated with a few, thin shoreline tongues, the presence of laterally extensive erosional surfaces on the shelf, and high sediment supply to basin-floor fan systems. Stationary trajectories record near-total bypass of sediment across the shelf and mass transfer to the basin floor. [source] | ||||||||||