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Houston Geological Society Bulletin

Abstract


Houston Geological Society Bulletin, Volume 42, No. 3, November 1999. Pages 9-9.

Abstract: Structural Arrays and Depositional Geometries in Hydrocarbon Provinces: A View from Orbit

By

Patricia Wood Dickerson
Lockheed Martin Space Operation Geologist
NASA Office of Earth Sciences

Exploration success, whether for resources on Earth or on neighboring planets, depends on an explorer's skill in three-dimensional visualization and pattern recognition. In some provinces, fault and fracture patterns replicate from the scale of an entire orogen down to the scale of a thin-section. In repeatedly and complexly deformed regions, the challenge becomes one of discriminating among superposed patterns-critical for evaluating trap integrity and predicting porosity/permeability distribution. Three-dimensional relationships between structures, basin configurations, sediment-body geometries, and volcanic vent distribution are readily observable in photographs by astronauts. Photographic data can be registered to maps and plots of other data and co-displayed using off-the-shelf Previous HitcomputerNext Hit programs. Such displays reveal details of source-reservoir juxtapositions and variations in fracture networks over a basin.

The primary pattern of rifts, for example, is one of long, straight, steeply dipping faults bounding basins that are longer than they are wide. Basins are generally half-grabens, and the flanks with greatest structural relief are depositional sites for coalesced alluvial fans. Axial lakes with evaporites, abundant algae, and fine-grained, low-permeability sediments provide oil-prone source beds. Half-grabens are separated by transfer zones, across which the tilts of grabens reverse. Volcanic vents occur at rift/transfer-zone junctions and, less commonly, along basin-bounding faults; thermal effects on surrounding strata are minimal. Most of these attributes can be examined in single synoptic frames captured from orbit.

Geomorphologist Hoover Mackin observed that geology is rarely a Previous HitscienceNext Hit of brilliance; it is a Previous HitscienceTop of wisdom. The best geologist is one who has observed a lot of rocks from every possible vantage point. Orbiting spacecraft provide an exceptional vantage point for viewing rocks at the scale of an entire tectonic province, for the eyes and minds of informed observers.

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