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Regional Mapping of Basement and Sedimentary Interfaces in the Deep Waters of the Andaman Sea Basin using Marine Magnetic and Gravity Data

Kivior, Irena¹; Chandola, Sandeep K.²; Lee, Beng Chong²; Nordin, Aisyah M.²; Markham, Stephen¹; Hagos, Fasil¹
¹Archimedes Consulting, Adelaide, SA, Australia.
²PETRONAS Carigali, Kuala Lumpur, Malaysia.

A magnetic and gravity study, aimed at mapping the top of crystalline basement and other detectable sedimentary interfaces as well as magnetic lineaments, was conducted over part of the deep water Andaman Sea basin, in offshore Myanmar. Marine magnetic and gravity data acquired simultaneously with a regional 2D seismic survey, was interpreted to produce depth maps of the Pre-Tertiary crystalline and economic basement as well as a Tertiary inter-sedimentary erosional surface.

Horizon interpretation was conducted by applying Energy Spectral Analysis techniques in a two stage process. First the Multi-Window Test (MWT) was applied to both the magnetic and gravity data on a coarse mesh of stations with the aim of identifying a depth-plateau corresponding to the particular horizon of interest. The depth plateaus correspond to interfaces where there is a significant magnetic susceptibility or density contrast. These plateaus were then laterally related to produce a coarse skeleton map of each horizon. In the second stage, the ESA-Moving Window procedure was applied on a dense mesh to the potential field data, using the optimal window sizes derived from the MWT stage.

The deepest horizon mapped is interpreted as the top of the crystalline basement, while the shallower horizon was found to have good correlation with depth estimates of seismic (acoustic) basement. Comparison with seismic interpretation undertaken along some seismic profiles indicate that the shallowest horizon shows broad correlation with a Tertiary, erosional surface event detected from the seismic.

 

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012