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Sea Level Changes |
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We have chosen the Maldive Islands for our INQUA Commissional Research Project (ICRP) because we believe that this is an area where we can make a significant contribution to Sea Level Research. The reasons are four-folded: (1) The Maldive Islands remain virtually unexplored with respect to sea level changes despite it potentials and strategic position. (2) The Maldive 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 addresses 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. |
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. (2) Reconstructing
the Holocene sea level history in details. (3) Answering
the question on tropical climate at 20 ka and around 12 ka.
Subsequent transgressional positions and the last interglacial level.
Documenting decadal signals.
Tracing possible evaporation effects on dynamic sea surface.
Reconstructing ocean circulation changes.
Dating past sea level positions
Tracing the corresponding climatic conditions
Modeling the controlling global system
Confirmed international
participation: Nils-Axel
Mörner Sweden coordinator,
on-shore geology M Richard
Fairbanks USA dating,
general expert M Peter Ramsay
South Africa off-shore
geophysics & diving M Colin Woodroffe Australia micro-atoll
sampling M Michael
Tooley England paleoenvironmental
studies M Douglas
Grant Canada
on-shore
geology M Roger McLean
Australia micro-atoll
sampling M Chas Anderson
the Maldives submarine
notches M Bjarne
Lembke Sweden medical
doctor, diving M Young scientists: Mohamed
Ali the Maldives local leader,
island formation M Sue Dawson
Scotland
micropaleontology,
tsunamis W
Jacques
Laborel
France
reef
bioecology & diving
M
Shahidul
Islam
Bangladesh
lagoonal
core analysis
M
Caroline
Rufin
France
geomorphology
W
V.J.
Loveson
India
remote
sensing
M
Researcher-1-3
South
Africa
assistance
to Ramsay
MW
Researcher-4-6
USA
assistance
to Fairbanks
MW
Researcher-7
Sri Lanka
project
participant
MW
others
to be added
regional
students
from the region
MW
Local
Male representatives
Ismail
Shafeeu
the
Maldives
Minister,
environment
M
Mohamed
Khaleel
the Maldives
Director
of Environment
M
Hussain
Naeem
the
Maldives
environmental
assistant
M
Hussan
Maniku
the Maldives
diver, local specialist
M
Sea
Explorers
the
Maldives
diving
MW
Omar
Naseer
the
Maldives
submarine
(Whale Submarine)
M
others
to be added
the
Maldives
local
input
MW
Duration: 2000 Reconnaissance inspection
and site selection Field expedition-1 lagoonal
coring, diving on-shore
and near-shore studies Analyses dating,
sediment core analyses 2001 Field expedition-2 off-shore
geophysics, coring, diving island
studies, micro-atoll samples Analyses interpretation
and analyses 2002 Field expedition-3 coral core
drillings core sampling Analyses core sample
analyses Workshop
integration data presentation
and Syntheis results
and conclusions
2003
Analyses
summary
and conclusions
presentation
at INQUA in Reno
Workshops/meetings: (1) project
workshop-1 on the Maldives in 2000 (2) training
course (TP-2) in 2001 or 2002 (3) project
workshop-2 on the Maldives in 2001 (4) concluding
project meeting in 2002 (5) report
at INQUA in Reno in 2003
Relations to other
international projects: (1) ODP
Sea Level Project (a direct link via Fairbanks) (2) IGCP-437
new sea level project (3) PAGES-LOIZC
project (4) INQUA
Commission on Paleoclimate (5) The
Alliance of Small Island States (6) IPCC
(the sea level part)
Communications: We will
continually report on the progress of the project by updating this entry
in our homepage. You are also invited to communicate directly to anyone
of the team members and especially the co-ordinator (Email:
sea@pog.su.se). Nils-Axel
Mörner
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. 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.
Integrated Coastal Zone Management, , p. 17-20. ICG Publ. Ltd ODP, 1990.
Leg. 115, Hole 714A and 716B (the Maldives). Prudy,
E.G., 1981. Evolution of the Maldive atolls, Indian Ocean. Proc 4th
Int. Coaral Reef Symp, 1, 659. Woodroffe,
C.D., 1992. Morphology and evolution of reef islands in the Maldives.
Proc. 7th Int. Coral Reef Symp, Gaum, 1992, 2, 1217-1226. Purdy,
E.G. & Beertrand, G.T., 1992. Atoll carbonate platform development in
the Maldives, Indian Ocean. AAPG, Studies in Geology, 34, 1-56. Report
from the 1st Expedition of the Maldives Project
Anderson, 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.
From October 7 to October 28, we run the 1st Expedition of the Maldives
Project in collaboration with the Ministry of Environment in Male.
5 days research in Male and neighbouring areas
10 days boat-expedition to the Goidhoo—Baa Atolls
7 days research in Male and neighbouring areas
We note the following main results:
The recording of Last Interglacial beds (for the first time)
The collection of 7 sediment cores of lagoonal mud (for the first time)
The recording of notches and caves in pre-Holocene reefs
The identification of different Holocene sea level stands
Sampling of soil sections and two mangrove swamps
The recording of a total absence of any recent sea level rise
The recording of a young (last 20 years) sea level fall
The documentation of present coral reef status (post-bleaching)
Establishment of a fine local network for coming studies
WE DID IT: found Last Ingerglacial rocks, took lagoonal sediment cores,
collected several samples for dating sea level changes, and finally
recorded a total absence of traces of a present sea level rise —
on the contrary a significant regression.
The boat of the Ministry with the team: Niklas, the crew, Sue, Francois,
Caroline, Shahidul, Bjarne and Dago. Motto: "je planche —
donc, je sui" (neo-Cartesius, 2000).
VILIGILI ISLAND: multiple sea level indicators.
VILIGILI ISLAND: the Last Interglacial corals and beachrock in the foreground
and the lonely tree on the rockshore (this tree has remained in this
position for some 40 years and was a marker for the prisoners coming
and leaving this island).
FOHODOO ISLAND: beachrock cut into a rock cut platform at a slightly
higher sea level and today’s bioerosion not reaching up to this
level, hence indicating a recent regression (like in so many other islands
visited).
SHAHIDUL’S SWAMP, GOIDHOO: a marine embayment became successively
more shallow and turned into a mangrove swamp which was later transformed
into an alluvial basin.
Informant: Nils-Axel Mörner