| Autor: |
J.F. Lecolle, G. Cabioch |
| Rok vydání: |
1988 |
| Předmět: |
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| Zdroj: |
Marine Geology. 81:241-260 |
| ISSN: |
0025-3227 |
| DOI: |
10.1016/0025-3227(88)90030-8 |
| Popis: |
The Holocene-Pleistocene unconformity is identified from radiocarbon dating of coral samples taken from drill holes through the Ricaudy fringing reef at Noumea (New Caledonia). Analysis of facies and diagenetic features permit the reconstruction of the Recent reef history and allow the recognition of an unconformity between Holocene and Pleistocene coral limestones. The Holocene-Pleistocene boundary appears at different depths in the fringing reef: about −3 m near the shoreline and −5 to −6 m near the seaward reef edge. This unconformity is related to emergence and subaerial exposure of a Pleistocene reef which has retained freshwater diagenetic features and an overlying paleosol. The overlying Holocene coral reef complex formed during the following transgression. Radiocarbon dating of the Holocene reef samples indicates that reef growth reached rates of 5 mm/yr. Two ages of 5690 ± 90 yrs B.P. and 4910 ± 420 yrs B.P. are found at low tide level. This indicates the age at which the reef reached sea level. Two hypotheses can be proposed to explain the cessation of reef growth in the Ricaudy fringing reef at 5500 yrs B.P.: (1) active uplift coeval with Holocene transgression, and (2) high sea level in the Holocene. The occurrence of a high stand in the sea level at 5400 yrs B.P. is the most probable; ample evidence is found in some places on New Caledonia. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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