--> Abstract: Topographic-keyed Sequence Models: Explaining and Predicting the Development of Basin-floor (Lowstand) Fans within Sequences, by Art D. Donovan; #90914(2000)
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Art D. Donovan1
(1) Exxon Ventures, Houston, TX

Abstract: Topographic-keyed Previous HitSequenceNext Hit Models: Explaining and Predicting the Development of Basin-floor (Lowstand) Fans within Previous HitSequencesNext Hit

Depositional Previous HitsequencesNext Hit display depositional topography along Previous HitsequenceNext Hit boundaries (erosional), within Previous HitsequencesNext Hit (constructional), and as relict physiographic relief. Analysis of Previous HitsequencesNext Hit deposited in a variety of tectonic settings indicates that lowstand fan development is directly related to depositional relief of the underlying Previous HitsequenceNext Hit boundary.

In the datasets studied, three distinct types of depositional Previous HitsequencesNext Hit were identified. Low-relief Previous HitsequencesNext Hit have Previous HitsequenceNext Hit boundaries with slopes of <1 degree and relief of < 50 meters. As might be expected, these Previous HitsequencesNext Hit lack lowstand fans. Moderate-relief Previous HitsequencesNext Hit have Previous HitsequenceNext Hit boundaries with slopes of .5 to 3 degrees and relief of 50-150 meters. Although these Previous HitsequencesNext Hit display distinct clinoform development, they lack lowstand fans. High-relief Previous HitsequencesNext Hit have Previous HitsequenceNext Hit boundaries with slopes of 1-3 degrees and relief 180 meters. These Previous HitsequencesNext Hit contain lowstand fans.

These relationships indicate that there is a Critical Depositional Shelf Break that controls slope stability or failure during relative sea-level falls. In basins where depositional relief is less than the Critical Shelf Break, progradation continues during relative sea-level falls. Resulting low- to moderate- relief Previous HitsequencesNext Hit lack lowstand fans. In basins where depositional relief is greater than the Critical Shelf Break, slumping, canyon development, fluvial capture, sediment by-pass, and fan development occurs during relative sea-level falls. In the datasets studied, the threshold for the Critical Shelf Break and the development of high-relief Previous HitsequencesNext Hit is erosional depositional relief of 150-180 meters. Topographic-keyed Previous HitsequenceTop models provide explorationists with a powerful tool to explain and predict fan development in a wide variety of depositional basins.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana