--> Abstract: Changing Our Own Thinking: The “Structural Styles” of Conventional and Unconventional Fold-Thrust Belts, by Ed Gilbert; #90072 (2007)

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Changing Our Own Thinking: The “Structural Styles” of Conventional and Unconventional Fold-Thrust Belts

Ed Gilbert
Devon Energy, Houston, TX

Less obvious than the plate tectonics “revolution” are equally fundamental changes in structural geology brought about by rigorous analytical techniques, improved seismic imaging, and access to formerly inaccessible environments. Most of us were and are trained to recognize a set of separate and distinctive “structural styles”, each with its suite of structural traps, and “rules” for their interpretation. The first rigorously analyzed “style” was the foreland fold-thrust belt (FTB), where quantitative concepts of material balance were developed. Most “rules” are based on principles developed for North American foreland FTBs, long considered paradigms. In reality, however, the Appalachians and Canadian Rockies are not universal paradigms. The foreland FTB is simply one – relatively limited – subtype of a broader FTB “style”, and one member of a very broad continuum that grades into other “styles”. As long as thirty years ago it was clear that several basic interpretational “rules” of the FTB style were violable. Subsequent work, illustrated by examples from various continents and geological environments, reveals considerable variation within the FTB style. In reality, the idea of styles is an artifact of the human desire to create bounded categories within a natural continuum that we only dimly understand. While styles are a useful classification system, we must never lose sight of the fact that “rules” associated with “styles” are not natural laws. The interpreter must remain willing to identify and accept exceptions to the rules. It is a reminder that ultimately there are no “unconventional” ideas, only minds open to new possibilities.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece