Print this page3-D Interpretation of Carbonate Margin Geometries from Digital Outcrop Models: The Escarpment of the Maiella Platform Margin
Maria Mutti1, John Thurmond2, David Hunt2, Uwe Baaske3, and Arndt Peterhänsel1
1University of Potsdam Germany, Potsdam, Germany
2Hydro Oil and Energy Research Center, Bergen, Norway
3Shell International Exploration and Production, The Hague, Netherlands
The Maiella platform margin outcropping in the central Apennines in Italy is a superb example of a Cretaceous escarpment margin, onlapped by basinal megabreccias, turbidites and pelagic carbonates. Although the location of the escarpment is undoubtedly recognizable from field relationships, geometrical and facies changes, the steep and often inaccessible terrain hinders a detailed mapping of its complex 3D form.
The integration of satellite images onto a globally referenced digital elevation model (DEM) has allowed the 3D rendering of geometrical and stratigraphic data previously acquired through field work. Through this methodology it is possible to visualize, analyze and interpret geological information at a regional scale and to extend the traditional 2-dimensional approach to true 3D, opening up an entirely new way of looking at large-scale stratigraphical correlations and geometrical reconstructions. The features mapped in 3D have been further checked with D-GPS point data.
The analysis of geometrical relationships between the horizontally bedded, massive platform units and the onlapping packages, consisting of megabreccias and recessive interbedded pelagic carbonate, has allowed to reconstruct the position of the escarpment surface. The escarpment surface is terraced into step-wise blocks, likely bounded by faults. Megabreccias tend to onlap the platform by resting on the least dipping portions of the blocks. Furthermore, the escarpment surface shows a significant lateral change in dip and orientation. The data acquired in this study suggest that the escarpment was not a line, but rather a knob feature onlapped by basinal deposits over at least 180°. This interpretation honors all existing field data and provides a simple explanation for the occurrence of megabreccias and pelagic carbonates in the inner platform area.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas