Emerged reefs

Abstract

The emerged reefs can be expressed by several morphological features from the single coral colony (microatoll) to extensive development of coral terraces. Several causes can be invoked to explain the occurrence of emerged reefs in the various regions of the world. Among these causes, the uplift of coral reefs in tectonically active regions is probably the most widespread. Nevertheless, the occurrence of such coral terraces in these tectonic zones is also dependant on eustatic sea-level variations. Several sites in the world display extensive sequences of raised reefs including the well-known sites from Barbados in the Caribbean, Papua New Guinea and Vanuatu in the Pacific Ocean, and Indonesia in the Indian Ocean. Uplifted atolls in some parts of the world can also attest to the presence of lithospheric flexures as observed in the Cook-Sociéty Islands or in the Loyalty Islands. Isostatic readjustments can be invoked to explain the mid-Holocene relative high sea level. The research carried out on these morphological features has highly improved our knowledge of Late Quaternary climatic and eustatic sea-level variations, their tectonic context, and also the upper earth rheology. Further studies will provide additional data on these topics of broad interest in the framework of earth science.