230Th/U dating of Last Interglacial brain corals from Bonaire (southern Caribbean) using bulk and theca wall material

摘要: Abstract We compared the suitability of two skeletal materials Atlantic brain coral Diploria strigosa for 230Th/U-dating: commonly used bulk material comprising all elements and denser theca wall material. Eight fossil corals presumably Last Interglacial age from Bonaire, southern Caribbean Sea, were investigated, several sub-samples dated each coral. For four corals, both ages activity ratios agree within uncertainty. Three show significantly older their than as well substantially elevated 232Th content (230Th/238U) ratios. The samples another younger lower corresponding samples. This also contains a considerable amount 232Th. application available open-system models developed to account post-depositional diagenetic effects in shows that none can successfully be applied Bonaire corals. most likely explanation this observation is assumptions are not fulfilled by our data set. Comparison enables us obtain information about processes affected showing apparently probably contamination with secondary (detrital) phase. source detrital carbonate sand. higher (230Th/232Th) ratio implies would have much stronger impact on contaminant Earth threshold reliability criterion generally value 1 ng g−1. its was influenced more one process. A potential scenario combination U addition pore infillings. Our results dense D. less behaviour better suited 230Th/U-dating obvious fact reflect origin (∼125 ka), whereas either or younger. However, some 230Th/U-ages similar. strictly reliable obtained exceptionally well-preserved frequently findings should applicable (Mussidae) found tropical oceans worldwide may enable similar architecture, even if skeleton altered diagenesis. we consider (120–130 ka), along recently published 118 ka, provide first comprehensive dating reef terrace at (118–130 ka), which agreement timing duration other records.