Holocene evolution and accumulation rates for Rodrigues Fringing Reef in the Southwest Indian Ocean

Rodrigues is located at latitude 19°43' S and longitude 63°25' E in the Southwest Indian Ocean and features the best developed reefs in the Mascarenes.

In 2001 a field expedition to Rodrigues recovered six drill cores using a portable hydraulic drilling rig. In all, two cores were recovered from the windward margin (cores 10 and 17), with a maximum depth of penetration of 4 m. Four cores were recovered from the leeward margin (8, 14, 15, 18) where the maximum depth penetration attained was 4.2 m. Recovery ranged from 23 to 63 %.

Thin sections were made and examined petrographically. Radiocarbon dating was performed on selected corals from the base of each core interpreted to have grown in situ and to be free from intraskeletal contamination.

Radiometric dating suggests that Rodrigues reefs approached sea level between 3.1 ± 0.3 cal kyr BP and 1.3 ± 0.2 cal kyr BP. In fact, the windward margin apparently grew to within 2.5 m of present day sea level by approximately 2.7 ± 0.2 cal kyr BP. The leeward margin approached modern day sea level more recently between 1.3 ± 0.2 cal kyr BP and 2.4 ± 0.3 cal kyr BP. Rates of vertical accretion for the top 4 m of the cores range from 0.46 - 1.96 m / kyr.