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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 66 (1982)

Issue: 10. (October)

First Page: 1708

Last Page: 1708

Title: Analysis of Simultaneously Acquired Airborne Gravity and Aeromagnetic Data in Eastern Overthrust Area: ABSTRACT

Author(s): R. Hartman, D. Pasicznyk, C. Curtis

Article Type: Meeting abstract

Abstract:

Continuously recorded airborne gravity surveying is a new airborne geophysical technique, conducted in a gridded survey mode in combination with simultaneously acquired aeromagnetic data. The interpretation of the two data sets was achieved by fitting a series of layered structural surfaces to the gravity data, guided by the approximate depth to critical subsurface sources obtained from detailed analysis of the magnetic data. The interpretation of the aeromagnetic survey data indicates the presence of a very deep horizon in excess of 25,000 ft (1,620 m) in some areas. Although the possibility that these depths arise from intrabasement sources is strong, a structural surface based on the gravity field can be constructed to conform with this horizon which appears reasonable The more common depth to probable crystalline basement derived from the magnetic data is about 15,000 to 20,000 ft (4,570 to 6,100 m). The relief that occurs on this surface is again obtained from the analysis of gravity data.

The importance of being able to correlate both surfaces adds considerable credibility to the interpretation. It is believed that the major thrust surfaces may be identified by the recognition of density contrasts between the Cambrian-Ordovician rocks, particularly the limestones, and the overlying shales. In addition, through the correlation of the magnetic and gravity data, the depth and the relief on the thrust sheets as well as on the basement surface can be determined. Wedges of crystalline rock from the basement apparently incorporated into the thrust sheet in some locations are also suggested by the magnetic data, and this is supported by small increases in the density contrasts. These implications of the subsurface have great significance in the exploration for petroleum in the area.

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