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The Interplay of Tectonics, Paleogeography and Paleoclimatology in Reconstructing Global Paleodrainage Systems Through Time

Previous HitPaulNext Hit J. Markwick1, John M. Jacques1, and Previous HitPaulTop J. Valdes2
1 Getech, Leeds, United Kingdom
2 Bristol University, Bristol, United Kingdom

The nature and flux of siliciclastics to the world's continental shelves is a direct consequence of the complex interplay of hinterland tectonics, geomorphology and climate. These factors change through time, which can affect not only the character and amount of sediment that is transported to downstream depositional basins, but also where that sediment is delivered. Understanding the dynamics of paleodrainage systems is therefore critical for predicting the distribution and character of clastic reservoir facies, especially in frontier areas.

In this study, we have applied an integrated, global GIS-based analysis of modern ‘blue-line' drainage network topology, river long-profiles, regional tectonics, landscape dynamics (paleogeography) and paleoclimate modelling, to define paleodrainage systems. We present examples from the Maastrichtian (Late Cretaceous) and Present Day.

The results demonstrate the importance of understanding the detailed paleogeographic context of margins and their hinterlands, which requires a thorough knowledge of the underlying tectonic framework. Paleodrainage reconstructions based solely on ‘blue-line' drainage net analysis (methods developed in the 1940 and 1950's by Horton and Strahler) provide powerful geometric descriptions of modern systems that may be used to identify discontinuities in the drainage topology. However, this should be viewed with caution when applied to areas affected by Pleistocene glaciation or in tectonically active areas such as SE Asia. Correctly defining the distribution of paleodrainage is especially important for geologic intervals with elevated global temperatures, such as the Mesozoic, for which model experiments indicate a greatly enhanced hydrological cycle (average Maastrichtian runoff values of 2.5x modern values).

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005