William E. Galloway, 1985. "Hydrocarbons in Fluvial Deposits of the Gulf Coast Region", Recognition of Fluvial Depositional Systems and their Resource Potential, Romeo M. Flores, Frank G. Ethridge, Andrew D. Miall, William E. Galloway, Thomas D. Fouch
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The following pages review examples of petroleum resources in fluvial deposits of the Gulf Coast Tertiary Basin. The fluvial depositional architecture of the Gulf Coast was described in detail by Galloway (1981).
The thickness and relationship of fluvial systems to other deposi-tional facies are dependent on the rate of sedimentation compared to the rate of basin subsidence. In coastal plain sequences containing progradational (offlap) depositional episodes, this interplay determines the distribution of fluvial deposits of both the fluvial system and deltaic plain relative to progradational facies of the delta margin (Fig. G-16). Example A, in which rate of subsidence is high because deposition occurs directly upon oceanic crust, is typical of relationships seen in the Tertiary fill of the Gulf Coast Basin. Example C, in marked contrast, reflects rapid progradation onto stable continental crust. This example, which is typical of the shallow water and stable platforms of Mid-Continent basins, results in extensive flu-vial incision and cannibalization of progradational deposits. Example B reflects facies relationships in Cretaceous units of the Rocky Mountain foreland basin and seaway.
The Frio (Oligocene) depositiorial episode typifies the depoitional and structural framework of fluvial systems in the North-west Gulf. Further, it is a highly prolific producer of oil and gas. It will serve as an example for discussion of resource distribution.
The Frio Formation (Texas Coastal Plain) and its updip equivalent, the Catahoula Formation (Fig. G-17), consist of several distinct depositional systems (Fig. G-18). Major progradational delta systems, designated the Norias and Houston delta systems, are