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Book Chapter

The Volcanic Basement of the Maldives

January 01, 2004


The nature and age of the Maldive basement are based on material recovered at ODP Site 715 and the two industry exploration wells, NMA-1 and ARI-1. Site 715, on the eastern oceanward slope of the Maldivian archipelago (Figure 3), recovered 76.6 m of basalt lava flows. Three limestone units with basalt clasts were interbedded with the basalt lava flows in the upper part of the section. The upper parts of the individual basalt flows were weathered and oxidized; these have been interpreted as lava flows erupted under subaerial conditions (Backman et al., 1988). With 40Ar/39Ar dating, these basalts yielded an age of 57.2 ± 1.8 m.y. (Duncan and Hargraves, 1990).

The Elf Aquitaine well NMA-1, drilled in the North Male atoll lagoon, penetrated 115.5 m of basalts below the carbonate section. Alternating hard and soft, weathered 10-m-thick lava beds were composed of black to green aphanitic basalts with olivine. The age of these basalts was determined with the 40Ar/39Ar method to be 55 m.y. (Aubert and Droxler, 1996). This is consistent with the age from the ODP Site 715 and shows that these two dates provide reliable information about the timing of the basalt basement formation.

The Shell ARI-1 well was drilled in the central part of the Inner Sea (Figure 5). In its bottom section, the well encountered 50 m of weathered basalts. The severe degree of basalt alteration prevented reliable dating.

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AAPG Studies in Geology

Seismic Expressions and Interpretation of Carbonate Sequences: The Maldives Platform, Equatorial Indian Ocean

Andrei V. Belopolsky
Andrei V. Belopolsky
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André W. Droxler
André W. Droxler
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American Association of Petroleum Geologists
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January 01, 2004




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