Coral Reefs (1988) 7:57 68 Coral Reefs @ Springer-Verlag 1988 Late Holocene sea level indicators from twelve atolls in the central and eastern Tuamotus (Pacific Ocean) P.A. Pirazzoli 1,4, L. F. Montaggioni z, 4, B. Salvat 3, 4 and G. Faure 2, 4 1 (CNRS) 16 rue de la Grange Bateli+re, F-75009 Paris, France 2 Universit6 de la Rbunion, B.P. 5, F-97490 Sainte-Clotilde, R6union Island, France DOM 3 Laboratoire de Biologie Marine et Malacologie, E.P.H.E., Centre Biol. Ecol. Trop. M6d., Universit6 de Perpignan, F-66025 Perpignan Cddex, France 4 Antenne Museum - EPHE, Centre de l'Environnement de Moorea, B.P. 1013, Moorea, French Polynesia Accepted 2 September 1987 Abstract. New sea-level data for the late Holocene period are reported from twelve atolls of the Tuamotu archipe- lago: Faaite, Hikueru, Marokau, Hao, Amanu, Ta- takoto, Pukarua, Nukutavake, Vairaatea, Tureia, Nuku- tipipi, and Hereheretue. The data come from coral con- glomerate outcrops, coral colonies in growth position, in situ reef framework and marine notches; they give consis- tent results, and their ages are controlled by 29 radiocar- bon datings. The Holocene MSL remained 0.8_+0.2 m higher than at present, from before 4000 years BP until at least 1500 years BP, then dropped gradually to the present level. This pattern is very similar to that reported from the northwest Tuamotus, suggesting the absence of measurable differential vertical movements over a dis- tance greater than 1300 km during the late Holocene. Ef- fects of the 1983 cyclones on reef morphology are re- ported from some atolls and radiocarbon dates of some storm-generated reef blocks are given. Introduction In October 1983 one of the authors (P.A.P.) joined a French Polynesian Administration team on board the "Astrolabe" on one of its biannual tours of 14 atolls in the central and eastern Tuamotus. The visit to each atoll was usually brief, generally last- ing one whole day, though only a few hours in some cases. Consequently, the geomorphological survey was not systematic and most often limited to a distance of a few kilometres from the landing point, usually on the lee- ward side of the atolls near a village. The main objective of the survey was a search for evidence of former sea-level stands, in order to compare them with other data from the South Pacific and to help test global and regional models of relative sea-level change. During the tour we observed effects of the 1983 cyclones in several atolls and sampled reef blocks previously projected on reef flats by former cyclones. Out of the 14 atolls visited, three (Reao, Vahitahi and Anaa) provided sufficient data for a separate publication (Pirazzoli et al. 1987 a, b; 1988). The present paper gives results obtained in the remaining eleven atolls (Faaite, Hikueru, Marokau, Hao, Amanu, Tatakoto, Pukarua, Nukutavake, Vairaatea, Tureia and Hereheretue), for which sea level records are presented for the first time. In addition this paper incorporates observations made by B.S. in 1982 in Nukutipipi atoll. The report on Hao in- cludes dates from drill holes already mentioned by Deli- brias et al. (1974). L.F.M. provided petrological and mineralogical anal- yses and G.F. identified the corals; radiocarbon dating was performed at the Nieders/ichsisches Landesamt ffir Bodenforschung (Hannover). Geological and geographical setting of the Tuamotu islands The Tuamotu Archipelago consists of two main chains of islands including some 80 atolls spread over a distance of about 1600 km in a WNW-ESE direction. According to the bathymetric maps of Monti and Pautot (1973-1974) the Tuamotu atolls cap the top of a volcanic basement, which rises steeply from a huge rocky ridge, forming wide shelves at depths varying from 1500 to 3000 m. The age of the basement of the islands has been esti- mated to be at least 37.5 and 44 m.y. in the northwestern Tuamotu ridge according to the paleofauna (Clague and Jarrard 1973), and to conventional K-Ar dating (Duncan and Clague 1985). If the rate of horizontal translation of the Pacific plate in this area is taken into account (about 110 mm/year), the age of the basement near Tureia is probably 12 m.y. younger than near the northwestern Tuamotu border. The northwestern ridge is bordered in its southern part (Fig. 1) by a second chain of islands, from Pitcairn to Hereheretue, some of which are much younger than the northwestern Tuamotu atolls. Surface volcanic rocks