About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 9. (September)

First Page: 1582

Last Page: 1583

Title: Meteoritic Impact--Reservoir-Forming Process: ABSTRACT

Author(s): C. John Mann, John F. Mchone, Jr.

Article Type: Meeting abstract


Known impact sites caused by meteoritic bodies falling to earth's surface, together with frequency distributions for observed rates of material infall and those inferred from lunar, martian, and mercurian data for the Phanerozoic, indicate that meteoritic-impact features have been sufficiently common and large to justify their recognition by petroleum geologists. The rock-shattering and dome-forming process of impact cratering can and does result in unconventional petroleum reservoirs.

End_Page 1582------------------------------

Two oil fields in the Williston basin and one potential gas field in Algeria are interpreted to be reservoirs in fractured strata beneath buried impact structures.

In addition to fractured domal structures, impact events in water-bearing, poorly consolidated materials can produce large bodies comparable to sand-flow volcanoes and clastic dikes. Such permeable features, after burial and lithification, may or may not be found in sedimentary environments, such as starved basins, deltas, or lagoonal areas, in which petroleum reservoirs normally occur.

Impact features with petroleum accumulations are most likely to be formed in relatively young, shallow-marine depositional environments (water depths less than 200 m) merely because these structures are most favorably located relative to the time and place of petroleum origin and its later migration. Terrestrial impact sites in well-lithified ancient strata, even crystalline rocks, however, may become reservoirs if a subsequent transgression results in deposition of a basal marine sequence of petroleum-generating sediments.

The best means of recognizing subsurface-impact features are detailed stratigraphic analyses, local structural-anomaly recognition, and high-recognition seismic data. Potential reservoirs of impact origin will be randomly distributed geographically and temporally throughout stratigraphic sequences; prediction of their location will therefore be difficult. Lack of trends, preferential location, or predictable distribution of impact sites precludes systematic search strategies during petroleum exploration. Commonly, magnetic and gravimetric signatures of buried impact features tend to be so subtle as to be ignored by geologists and geophysicists, although known large surface impact sites typically display gravity deficiencies. Only those isolated anomalies which show an obvious circular ty can be readily distinguished as possible subsurface impact features. Constant alertness for subtle clues to the presence of subsurface impact structures during routine stratigraphic, structural, and seismic data analyses will be most effective in achieving their discovery.

End_of_Article - Last_Page 1583------------

Copyright 1997 American Association of Petroleum Geologists