The Maldives Project

This is a sea level project under the INQUA Commission on "Sea Level changes and Coastal Evolution", and relevant information are to be found under RT-1.

Preamble
(1) The Maldive Islands remain virtually unexplored with respect to sea level changes despite it potentials and strategic position.
(2) The Maltive Islands lie right in the deepest geoid hole in the world – some 100 m below the rotational ellipsoid. It is of the utmost importance to define the 20 ka regression limit in this area, because it would provide a direct clue to the possible deformation of the geoid relief. The same applies for successively younger sea level positions and the last interglacial level, too. In this area, we have ideal conditions to pinpoint this question.
(3) The Maldive Islands lie in an area where the dynamic sea surface is significantly lowered below the geoid level due to the extreme rate of evaporation. By investigating the Holocene sea level history in details, we may record changes in the evaporation rate. This also adresses a question of prime practical implications (global warming may lead to increased evaporation and, by that, to an increased lowering of the dynamic sea surface; i.e. a regional regression instead of a general transgression as often claimed).
(4) Fairbanks has proposed that the tropical region was significant cooler at 20 ka and that this acted to synchronize the two polar regions. Recent studies at Christmas Island show that this part of the tropics was significant cooler and without major variations at around the BÖ-YD oscillations. In the Maldive Islands, there are ideal possibilities to test these findings.

Project participants:

Nils-Axel Mörner Sweden coordinator, on-shore geology
ok
Mohamed Ali the Maldives local leader, island formation ok
Peter Ramsay South Africa off-shore geophysics & diving ok
+ group of 3-7 South Africa off-shore geophysics & diving ok
Michael Tooley England paleoenvironmental studies ok
Sue Dawson Scotland micropaleontology, tsunamis ok
Douglas Grant Canada on-shore geology ok
Roger McLean Australia micro-atoll sampling ok
Colin Woodroffe Australia micro-atoll sampling ok
Jacques Laborel France reef bioecology & diving ok
Richard Fairbanks USA dating, general expert ok
+ group of experts USA India core analyses, geochemistry ok
S. Islam Bangladesh Sub-commissional president ok

 

Anticipated results:
(1) Solving the burning sea level question of the long-term stability of the geoid relief.
establishing the 20 ka sea level position
subsequent transgressional positions
and the last interglacial level
(2) Reconstructing the Holocene sea level history in details.
documenting decadal signals
tracing possible evaporation effects on dynamic sea surface
reconstructing ocean circulation changes
(3) Answering the question on tropical climate at 20 ka and around 12 ka.
dating past sea level positions
tracing the corresponding climatic conditions
modelling the controlling global system

 

Program
Much of the work will be concentrated to the South Maalhosmadulu (Baa) and Goidhoo Atolls (Fig. 2-1-1) because circumstances are favourable here. Besides this is the area of Ali’s thesis (Ali, 2000).


Fig. 2-1-1. Nautical chart of the South Maalhosmadulu (Baa) and Goidhoo Atoll. Yellow area give the submarine channel where the 20 ka level should be able to trace with high precision. Blue areas are areas of lagoon coring. Red dot refers Hulhudhoo Island.


Fig. 2-1-2. Detailed nautical chart of the Goidhoo Atoll providing several traces of terraces and other shore features.


Fig. 2-1-3. Submarine topography of the Doru Kandu area rwcording terraces, a major channel and other shore features.


Fig. 2-1-4. The eastern part of the Goidhoo Atoll with basins, ridges and terraces, good for lagoonal coring and coral reef sampling.


Our intensions are to tackle the following issues:
The last interglacial and 20 ka island topography
Seismic profiling across the Baa Atoll
Studies and, maybe, drilling on land (e.g. Hulhudhoo island with red sandstone)
The 20 ka regression minimum
Geophysics over the Kuda Kanduolhi channel (Fig. 2-1-1)
Studies (and sampling) of the –130 m terrace (e.g. Fig. 2-1-3)
The submarine reef terraces
Geophysical studies of deeper terraces
The Doru Kandu terraces (Fig. 2-1-3)
The –70 m terrace at Kani and Rasov; diving & sampling
The east Goidhoo shore features
The terraces and thalias of the upper 30-40 m
Lagoonal coring (biostratigraphy, pollen, tsunamis)
The –50 m deep in the Baa atoll
The lagoon of Goidhoo (Figs. 2-1-2 & 4)
Micro-atoll studies
At suitable sites
Island migration and dynamics
At suitable sites
Soil stratigraphy & development
At suitable sites
Submerged buildings and old monuments
Viligili Island, the National Museum (Male)
Observations of present coastal trends
At suitable sites
Historical information
Collection of available information
Present and past tidal range
If possible

Selected references:
Agassiz, A., 1903. The coral reefs of the Maldives. Mem. Mus. Comp. Zool. Harvard Coll., 29, 1-168.
Ali, M., 2000. Reef island gemorphology: Formation, development, and perspectives of islands in Eta atoll, South Maalhosmadulu, the Maldives. Ph.D.-thesis, Univ. S. Wales, 296 pp.
Anderon, R.C., 1998. Submarine topography of Maldivian atolls suggests a sea level of 130 m below present at the last glaciation maximum. Coral Refs, 17 (4), 339-341.
Davis, P.S., Stoddart, D.R. & Sigeo, D.C., 1971. Reef forms of Addu Atoll, Maldive Islands. Symp. Zool. Soc. London, 28, 217-259.
Gardiner, J.S., 1902. The formation of the Maldives. Geogr. J., 19, 277-301.
Mörner, N.-A., 2000. Sea Level Changes and Coastal Dynamics in the Indian Ocean. In: Integrated Coastal Zone Management, p. 17-20. ICG Publ. Ltd
ODP, 1990. Leg. 115, Hole 714A and 716B (the Maldives)
Purdy, E.G., 1981. Evolution of the Maldive atolls, Indian Ocean. Proc 4th Int. Coaral Reef Symp, 1, 659.
Purdy, E.G. & Beertrand, G.T., 1992. Atoll carbonate platform development in the Maldives, Indian Ocean. AAPG, Studies in Geology, 34, 1-56.
Woodroffe, C.D., 1992. Morphology and evolution of reef islands in the Maldives. Proc. 7th Int. Coral Reef Symp, Gaum, 1992, 2, 1217-1226.