Testing the Formation of Modern Atolls with a Unique Carbonate Core Record from the Maldives
Emeritus professor André Droxler was selected by the Royal Society for a Wolfson Visiting Professor Fellowship at the Queen Mary University in London for collaborative research that tests Darwin's subsidence theory on the formation of coral reefs.
"Darwin linked the different types of reefs together in an evolutionary model that elegantly explained their interrelated origin through the slow and steady subsidence of low latitude volcanic edifices," says Droxler, who goes on with reverence to say that the degree of detail in Darwin's original1840's reef maps are still quite accurate today.
Not so is Darwin's original model, which didn't account for quaternary glaciation and concomitant sea-level fluctuation impacts on reef architecture. More recent theories, such as the 1930's Antecedent Karst Theory, account for the influence of climate, yet are limited by the data available from ancient to modern atolls.
The Maldives may hold the key to pinning down the answer.
The ring of islands, which are rooted on Late Pliocene carbonate bank, will not only provide some of the more critical missing data, but may also address some of the more pressing conservation issues associated with our warming climate.
The core dilemma
Droxler has been working in the Maldives for most of his career, but during a more recent visit in 2023 facilitated by a Fulbright Scholarship, he gained access to unique set of geotechnical core samples drilled during the design phase of the Malé-to-Thilafushi Link Bridge Project. Droxler recognized that they represented a unique opportunity to conduct a detailed academic study of the Quaternary record of an unsampled margin of the North Malé Atoll.
Unfortunately, the cores were not conserved once the original survey was complete in 2020. Droxler, with the help of the Maldives Ministry of National Planning and Infrastructure was able to recover them for research. "Such a core collection along an atoll margin is unique, with the exception of the existing cored boreholes along a few atolls (i.e. along the Mururoa atoll margin) in the south central Pacific Ocean locations of past nuclear tests," says Droxler.
They hope to test the idea that the origin of atolls is more likely due to minimal dissolution along the margins, with maximal dissolution in the center during times of exposure associated with Quaternary lowstands of sea level, rather than preferential coral growth and reef accretion along margins of a flat-topped volcanic bank.
A detailed record of sea-level fluctuation
The cores will also provide constraints on the history of sea-level rise and fall over the last 1-3 million years. Droxler believes that these cores preserve an archive of global sea-level changes at unprecedented resolution, and hopes integrate their results with established climatic records and sea level fluctuations during the Quaternary to Late Pliocene.
This is the second high-profile research fellowship Droxler has received in support of his research in this part of the world. More importantly, he wants to share his comprehensive knowledge gained through almost 40 years of collaborative research between industry, academia, and government.
EEPS chair Juli Morgan commends Droxler's achievement, "You have been energetic and quite successful at bringing in resources to support your ongoing research, which is an inspiration for all of us."