A New Coral Reef Province in the Gulf of Carpentaria, Australia: Colonisation, Growth and Submergence During the Early Holocene

Multibeam sonar mapping, drill cores and underwater video data have confirmed the existence of a previously unknown reef province in the Gulf of Carpentaria, Australia. Seven reefs, comprised of coral limestone that support living corals have been mapped so far and as many as 50 other reefs may exist in the region. U/Th ages show that reef growth commenced shortly after limestone pedestals were submerged by rising sea level around 10.5 kyr BP, making them the oldest reefs known in Australia. Reef growth persisted for ~2.0 kyr but it had ceased at most locations by ~8.0 kyr BP. Measurements of reef growth rates (0.95 to 4 m kyr-1), indicate that the reefs were unable to keep pace with contemporaneous rapid sea level rise (>10 m kyr-1), which is consistent with a 'give up' reef growth history. Core samples from reef platforms demonstrate that Pleistocene limestone is exposed in depths of 27 and 30 m below present mean sea level. These depths represent regionally significant phases of reef growth during a prolonged sea level still stand. We conclude that the reefs are therefore mostly relict features, whose major phase of growth and development relates to an earlier, pre-Holocene sea level stillstand.

多波束声呐测绘（Multibeam sonar mapping）、钻探岩心（drill cores）与水下视频数据证实，澳大利亚卡奔塔利亚湾（Gulf of Carpentaria）内存在一处此前未被发现的礁域。截至目前，已测绘出7座由珊瑚灰岩构成且支撑活体珊瑚生长的礁体，该区域内或存在多达50座同类礁体。铀钍测年（U/Th ages）结果显示，约在距今10.5 kyr BP海平面上升淹没灰岩基座后不久，礁体便开始发育，使其成为澳大利亚已知最古老的礁体。礁体发育持续了约2.0 kyr，但到距今8.0 kyr BP时，多数区域的礁体发育已停止。对礁体生长速率（0.95至4 m kyr⁻¹）的测量结果表明，这些礁体无法跟上同期快速的海平面上升（>10 m kyr⁻¹），这与“停止发育”的礁体发育历史相符。取自礁台的岩心样本显示，更新世（Pleistocene）灰岩裸露于现今平均海平面（mean sea level）以下27米与30米的深度处。这些深度对应了长期海平面稳定期内区域内重要的礁体发育阶段。我们据此推断，这些礁体大多为遗迹特征，其主要发育阶段与更早的全新世前（pre-Holocene）海平面稳定期相关。