Melt-water pulses

So far, the most complete and accurate sea-level record that encompassed the period between the Last Glacial Maximum and the present day is based on cores drilled offshore the Barbados coral reef . This record suggests a non-monotonous sea-level rise punctuated by dramatic accelerations, the so-called Melt Water Pulse events, that correspond to massive inputs of continental ice. The most extreme of these events, the so-called MWP1-A, initially identified in the coral-based sea level record from the Barbados island, suggests a sea-level rise of ∼20 meters between 14.1 and 13.6 ka . However, this event remains enigmatic and controversial. Barbados Island is relatively close to the former North-American ice sheet and the island itself belongs to an accretionary prism overlying an active subduction zone. The possibility remains that the apparent sea-level record may be flawed by tectonic or isostatic complications. Several records are consistent with its occurrence , but no broad agreement emerges about its timing and amplitude. Because of this lack of consensus, the temporal relationship between the MWP1-A and the abrupt, millennial-timescale, climatic events that punctuated the last deglaciation is a subject of controversial debates . Furthermore, the ice source responsible for such a step in sea-level rise is still elusive . Consequently, it remains a key issue to fully confirm the existence and amplitude of the MWP-1A by a precise coral reef record in a far-field site located in a oceanic basin distant from Barbados. The recent IODP Expedition 310 "Tahiti Sea Level" offers a unique opportunity to extend the existing Tahiti sea-level curve that documents the deglacial sea level rise for the last 13.8 ka . Located at a considerable distance from the major former ice sheets and characterized by slow and regular subsidence rates, the Tahiti coral reefs provide an ideal setting to constrain MWP events that are thought to have punctuated the last deglaciation. The offshore coring operations carried out during Expedition 310 recovered more than 400 m of post-glacial reef material, ranging from 122 to 40 m below modern sea level . Post-glacial coral material was selected using strict mineralogical and isotopic screening criteria in order to preclude any post-mortem diagenetic alteration of the coral skeleton. More than 60 U-Th ages were obtained on various types of corals characterizing shallow to deeper environments that extend the previous Tahiti record to 16 ka and allow to document the sea-level rise during the key period of the MWP-1A. Our results confirm the occurrence of an acceleration of the sea-level rise during that period. However, the timing and duration of this event differ significantly from observations from Barbados [3,. These new results indicate that the MWP-1A occurred at about 14.6 ka BP, synchronously with the Bølling onset. This allows us to revisit the relationship between the MWP-1A and the climate history of the last deglaciation. Their implications in terms of the potential sources of the ice that generated the MWP-1A will be also discussed.

It/hose tillIe, faci 1 ities and radiographic expertise were indispensable to th i s resea rch. Mr J. Hudson, from DuPont Corporation, for endless suppl ies of X-ray film. Mr D. Duncan, t~aster of the R.V. James Kirby, and crew members of that sturdy vessel, for their friendship, versatil ity, and sterling seamanship. The reef scientists of the North Queensland institutions, James Cook University, A.I .M.S. and G.B.R.M.P.A., who \<Jere ever ready with advice and support. Among others, Drs D.

Dep. of Earth and Planetary Sc., Nagoya Univ., Geocoastal Research Group, Univ. of Sydney, Dep. de Estrat. y Paleont., Univ. de Granada, Inst. of Geol. and Paleont., Tohoku Univ., Dep. of Ecol. & Evol. Bio., Univ. of California, AORI, Univ. of Tokyo, ANSTO, Inst. for Env. Res., Australia, Res. Sch. of Earth Sc., Austral. Nation. Univ., Lamont-Doherty Earth Observatory, USA, School of GeoSciences, Univ. of Edinburgh

The Birch effect is a pulse in soil C and N mineralization caused by the wetting of dry soils, but the role of the soil moisture increment (ΔSWC) is still poorly understood. We quantified the relationship between ΔSWC and the Birch effect, and its interactions with pre-wetting soil moisture (preSWC) and substrate supply. Two soils (clay loam and sandy loam) under a Pinus halepensis forest were subjected to rewetting in laboratory treatments combining different ΔSWC and preSWC values, with or without additional substrate (5 mg g -1 P. halepensis needles). Respiration flush (ΔR), changes in microbial biomass C (MBC) and net N mineralization (NMIN) were measured. Overall, we found a relationship with the form: ΔR=a ΔSWC +b, where the slope (a) was significant only when pre-wetting water potential was below a threshold value in the range of - * Corresponding author.

Introduction: Despite warmer conditions during the Last Interglacial, coral colonies of Orbicella were abundant and reached large sizes on many Caribbean reefs, including the extinct O. nancyi. Methods: To explore variation in growth rates, we examined the yearly mean linear extension of growth bands in two fossil Orbicella species and compared them with two modern species of the same genus from shallow waters of the wider Caribbean.We measured the linear extension of corals exposed in a fossil reef and their modern counterparts, from both in situ colonies and coral slab X-rays. Results: Few coral colonies showed autocorrelation or a linear trend on their linear-growth time series. A Bayesian ANOVA showed lower linear-extension rates of fossils compared to modern colonies and similar or lower than other fossil corals from the Pleistocene. Growth rates and growth form contribute significantly to the amount of tissue and size of coral colonies and can be a decisive trait for inter and intra specific competition. Discussion: It is unlikely that temperature or interspecific competition explain modern coral extension rates and the low rates of the fossils data, which seem to be controlled instead by past habitat conditions.

Calcification of microbial mats adds significant amounts of calcium carbonate to primary coral reef structures that stabilizes and binds reef frameworks. Previous studies have shown that the distribution and thicknesses of late Quaternary microbial crusts have responded to changes in environmental parameters such as seawater pH, carbonate saturation state, and sediment and nutrient fluxes. However, these studies are few and limited in their spatio-temporal coverage. In this study, we used 3D and 2D examination techniques to investigate the spatiotemporal distribution of microbial crusts and their responses to environmental changes in Integrated Ocean Drilling Program (IODP) Expedition 325 (Great Barrier Reef Environmental Changes) fossil reef cores that span 30 to 10 ka at two locations on the GBR reef margin. Our GBR microbialite record was then combined with a meta-analysis of 17 other reef records to assess global scale changes in microbialite development (i.e., presence/ absence, thickness) over the same period. The 3D results were compared with 2D surface area measurements to assess the accuracy of 2D methodology. The 2D technique represents an efficient and accurate proxy for the 3D volume of reef framework components within the bounds of uncertainty (average: 9.45 ± 4.5%). We found that deep water reef frameworks were most suitable for abundant microbial crust development. Consistent with a previous Exp. 325 study (Braga et al., 2019), we also found that crust ages were broadly coeval with coralgal communities in both shallow water and fore-reef settings. However, in some shallow water settings they also occur as the last reef framework binding stage, hundreds of years after the demise of coralgal communities. Lastly, comparisons of crust thickness with changes in environmental conditions between 30 and 10 ka, show a temporal correlation with variations in partial pressure of CO 2 (pCO 2), calcite saturation state (Ω calcite), and pH of seawater, particularly during the past~15 kyr, indicating that these environmental factors likely played a major role in microbialite crust development in the GBR. This supports the view that microbialite crust development can be used as an indicator of ocean acidification.

Integrated Ocean Drilling Program (IODP) Expedition 325 cored submerged reefs along the shelf edge of the Great Barrier Reef (GBR) to study sea-level and environmental changes and their impacts on reef communities and reef growth since the Last Glacial Maximum (LGM). Previous work defined five reef sequences (Reef 1

Reef response to Last Interglacial (LIG) sea level and palaeoenvironmental change has been well documented at a limited number of far-field sites remote from former ice sheets. However, the age and development of LIG reefs in the Great Barrier Reef (GBR) remain poorly understood due to their location beneath modern living reefs. Here we report thirty-nine new mass spectrometry U-Th ages from seven LIG platform reefs across the northern, central and southern GBR. Two distinct geochemical populations of corals were observed, displaying activity ratios consistent with either closed or open system evolution. Our closed-system ages (~129-126 ka) provide the first reliable LIG ages for the entire GBR. Combined with our open-system model ages, we are able to constrain the interval of significant LIG reef growth in the southern GBR to between ~129-121 ka. Using age-elevation data in conjunction with newly defined coralgal assemblages and sedimentary facies analysis we have defined three distinct phases of LIG reef development in response to major sea level and oceanographic changes. These phases include: Phase 1 (>129 ka), a shallow-water coralgal colonisation phase following initial flooding of the older, likely Marine Isotope Stage 7 (MIS7) antecedent platform; Phase 2 (~129 ka), a near drowning event in response to rapid sea level rise and greater nutrient-rich upwelling and; Phase 3 (~128-121 ka), establishment of significant reef framework through catch-up reef growth, initially characterised by deeper, more turbid coralgal assemblages (Phase 3a) that transition to shallow-water assemblages following sea level stabilisation (Phase 3b). Coralgal assemblage analysis indicates that the palaeoenvironments during initial reef growth phases (1 and 2) of the LIG were significantly different than the initial reef growth phases in the Holocene.

Samples of corals from all three previously reported Pleistocene localities in eastern Australia have been dated anew using the 230Th/234U technique. Results for two sites are confirmed, but the new results for the third site are older than previously reported and do not support a high sea level for isotope substage 5c. All sites are now referred to substage 5e.

D-alloisoleucine/L-isoleucine (D/L) ratios were measured in Tridacna gigas (the giant clam) whose ages were calibrated against radiometrically dated coral reef terraces from New Guinea and storm ridges on coral islands from the Great Barrier Reef. The results of 52 samples show several distinct intervals encompassing a fast epimerization phase at a rate of 0.077/ka for the first 8 ka, a transitional interval for the next 60 ka during which epimerization evolves at the rate of 0.006/ka, and the final phase between 60 and 185 ka when D/L ratios attain quasi-equilibrium (-1.30) at an average rate of 0.003/ka. The demonstrated relation between the D/L ratios and the radiometric ages is useful for estimating ages of undated or insufficiently dated terraces. A comparison of the "New Guinea curve" and other less completely dated curves from elsewhere demonstrates the effect of sedimentary temperature on the rate of epimerization through time. Refinements of the D/L reaction among coral reef terraces, coupled with a better definition of the kinetic model presented here, would improve our knowledge of the temperature history and the chronostratigraphy of Quaternary coral reefs.

Estimating the impact of environmental processes on vertical reef development in geological time is a very challenging task. pyReef-Core is a deterministic carbonate stratigraphic forward model designed to simulate the key biological and environmental processes that determine vertical reef accretion and assemblage changes in fossil reef drill cores. We present a Bayesian framework called Bayesreef for the estimation and uncertainty quantification of parameters in pyReef-Core that represent environmental conditions affecting the growth of coral assemblages on geological timescales. We demonstrate the existence of multimodal posterior distributions and investigate the challenges of sampling using Markov chain Monte-Carlo (MCMC) methods, which includes parallel tempering MCMC. We use synthetic reef-core to investigate fundamental issues and then apply the methodology to a selected reef-core from the Great Barrier Reef in Australia. The results show that Bayesreef accurately estimates and provides uncertainty quantification of the selected parameters that represent environment and ecological conditions in pyReef-Core. Bayesreef provides insights into the complex posterior distributions of parameters in pyReef-Core, which provides the groundwork for future research in this area.

ABST~CCr: Geologic reefs are the end-products of not only constructive processes that produce calcium carbonate, but also of destructive processes (e.g., bioerosion and wave action) that reduce solid substrate to sediment, and of physical processes that rework the reef fabric and transport sediment. A study was conducted at Cane Bay on the island of St. Croix, U.S. Virgin Islands to quantify the suite of processes that have influenced Holocene reef development. Data on carbonate production, reef accretion, bioerosion, and sediment transport were used to construct a detailed "carbonate budget" and to apply the findings of this study to the character of reefs observed in the fossil record. Total carbonate production on the reef ranged from 0 to 5.78 kg/m 2 per year, with a reef-wide average of 1.21 kg/m 2 per year (1.13 by corals; 0.02 by coralline algae; 0.06 by primarily molluscs, forams and echinoderms). Based on 7 cores, only 0.91 kg/m 2 per year of this have been retained within the reef interior. The remaining 0.24 kg/m 2 per year of sediment, along with the 0.06 kg/ m-' per year contributed directly by molluscs, etc., are deposited within reef channels and are probably flushed from the reef by major storms. Of the material recovered in the cores, 58% was either loose sediment and rubble or open void space. Much of the recognizable coral material was demonstrably reworked and out of place. Accretion rates across the shelf generally increased with water depth, as a result of active slumping along the steepening reef faee over the past 2,000-3,000 years. The importance of detrital material in the reef fabric and the major role played by secondary processes that constantly rework the substmte have resulted in a reef whose interior is more of a "garbage pile" than an in-place assemblage of corals cemented together into a rigid "framework." The physical similarities between the detrital fabric of the reef at Cane Bay and those found in many ancient deposits imply that the general processes operating along the Cane Bay shelf have persisted during much of the evolution of ancient reefs. It is proposed that our modern models overemphasize the importance of in-place framework as a criterion for an "ecologic reef.'"

Introduction: Despite warmer conditions during the Last Interglacial, coral colonies of Orbicella were abundant and reached large sizes on many Caribbean reefs, including the extinct O. nancyi. Methods: To explore variation in growth rates, we examined the yearly mean linear extension of growth bands in two fossil Orbicella species and compared them with two modern species of the same genus from shallow waters of the wider Caribbean.We measured the linear extension of corals exposed in a fossil reef and their modern counterparts, from both in situ colonies and coral slab X-rays. Results: Few coral colonies showed autocorrelation or a linear trend on their linear-growth time series. A Bayesian ANOVA showed lower linear-extension rates of fossils compared to modern colonies and similar or lower than other fossil corals from the Pleistocene. Growth rates and growth form contribute significantly to the amount of tissue and size of coral colonies and can be a decisive trait for inter and intra specific competition. Discussion: It is unlikely that temperature or interspecific competition explain modern coral extension rates and the low rates of the fossils data, which seem to be controlled instead by past habitat conditions.

Contemporary understanding of Holocene coral reef development is based primarily on sub-surface investigations of reef flat, back reef and lagoon zones. Few studies of Holocene fore reef development exist, constituting a significant gap in our understanding of reef evolution. The spur and groove (SaG) zone is a distinct, understudied, feature of fore reefs worldwide. We review SaG development from previous studies and present 29 new SaG short cores with 52 14 C and UeTh ages from six fore reef regions of Heron and One Tree reefs, the first such data from the Great Barrier Reef. Remarkably, we found that SaGs do not necessarily accrete in the same direction as their adjacent reef flat. We identified three modes of reef flat and SaG lateral accretion: Mode 1 e lagoonward accretion of both the reef flat and SaGs; Mode 2 elagoonward accretion of the reef flat but seaward accretion of the SaGs; Mode 3seaward accretion of both the reef flat and SaGs. Most SaG zones (five of the six studied) accreted in a seaward direction (Modes 2 or 3). Hydrodynamic conditions and local topography appear to be the dominant factors determining which mode occurs. Episodic high-energy events are also likely to play an important role in SaG formation. Our findings suggest that traditionally held models of reef evolution whereby lagoonal, mature reefs fill, developing into senile platform reefs, may not hold. Rather, reef flats may continue to expand seaward on their leeward, and semi-exposed fronts to increase in size while maintaining their lagoons.

Climate plays a central role in coral-reef development, especially in marginal environments. The highlatitude reefs of southeast Florida are currently non-accreting, relict systems with low coral cover. This region also did not support the extensive Late Pleistocene reef development observed in many other locations around the world; however, there is evidence of significant reef building in southeast Florida during the Holocene. Using 146 radiometric ages from reefs extending ~ 120 km along Florida's southeast coast, we test the hypothesis that the latitudinal extent of Holocene reef development in this region was modulated by climatic variability. We demonstrate that although sea-level changes impacted rates of reef accretion and allowed reefs to backstep inshore as new habitats were flooded, sea level was not the ultimate cause of reef demise. Instead, we conclude that climate was the primary driver of the expansion and contraction of Florida's reefs during the Holocene. Reefs grew to 26.7° N in southeast Florida during the relatively warm, stable climate at the beginning of the Holocene Thermal Maximum (HTM) ~ 10,000 years ago, but subsequent cooling and increased frequency of winter cold fronts were associated with the equatorward contraction of reef building. By ~ 7800 years ago, actively accreting reefs only extended to 26.1° N. Reefs further contracted to 25.8° N after 5800 years ago, and by 3000 years ago reef development had terminated throughout southern Florida (24.5-26.7° N). Modern warming is unlikely to simply reverse this trend, however, because the climate of the Anthropocene will be fundamentally different from the HTM. By increasing the frequency and intensity of both warm and cold extreme-weather events, contemporary climate change will instead amplify conditions inimical to reef development in marginal reef environments such as southern Florida, making them more likely to continue to deteriorate than to resume accretion in the future.

Samples of corals from all three previously reported Pleistocene localities in eastern Australia have been dated anew using the 23@T'f134U technique. Results for two sites are confirmed, but the new results for the thud site are older than previously reported and do not support a high sea level for isotope substage 5c. All sites are now referred to substage 5e. 0 1989 University of Washington.

Late Pleistocene raised coral reef terraces form extensive outcrops up to 5 km wide along the Saudi coast. Porites coral were dated using U/Th while clastic sediment from Jeddah was dated using thermoluminescence. The pooled mean age for the coral samples is 121.5±0.2 ka suggesting MIS 5e, even for the uplifted 16-20 m high terrace in the north at Haql. In Jeddah the MIS 5e back-reef succession is overlain by fluvial sediment that gave a TL age of 66±13 ka. The structure and faunal composition of the coral terraces suggests that they accumulated in broad shallow embayments following the last interglacial transgression. The consistent elevation of these terraces suggests that the central and southern Saudi coast has been tectonically stable for at least the past 125,000 years and the coral reef terraces (at 3.5-5.5 m elevation) are consistent with the MIS 5e sea level high-stand that peaked at 6-9 m above present sea level. The Saudi coastal coral terrace north of Duba shows progressive uplift to 16-20 m near Haql since 108-120 ka as a result of ongoing transform faulting in the Gulf of Aqaba.

Five Quaternary coral reef terraces have been recognized along Sharm E1Sheikh-Ras Mohammed coast, of which terraces 'V to II' form a well developed staircase at Um Seed, while recognized separately at Ras Mohammed. Terrace T was only observed as a reef patches at Sharm E1Sheikh-Ras Mohammed road. Terraces 'V to I' exist at elevations of-l(b.s.1.) to 0 m, 3-6 m, 10o12 m, 15-20 m and 25-35 m (a.s.1.), respectively. Uranium series dates of samples representing terraces 'V, IV, III, II and I' show ages grouped as ka, 118-125ka, 200ka, 280-300ka and older than 300ka, which are related to isotope stages 1, 5e, 7, 9 and 11, respectively. The variation of 8~80 for samples from these terraces show evidence of at least four major warm-wet climatic periods in relationship to high sea level and contemporaneous with the formation of the reef terraces. Faulting affects only the older terraces 'I and II', and along with the occurrence of terrace 'IV' of Last Interglacial age at elevation of 3-6 m suggest that the coastal area has not been subjected to major tectonic activities at least with the last 125 ka.

Understanding the transformation of unconsolidated sediments into their lithified equivalents is an essential concept in geology, and is especially complex for coral reef deposits accumulating at marine and terrestrial interfaces. Because corals are used as paleoclimatic and paleoenvironmental proxies, it is important to identify the extent of alteration to their skeletons. The geographic proximity of ancient limestone reefs and modern reefs in southern Florida provides an ideal location to study coral taphonomy in ...

The Houtman Abrolhos reefs, situated on the western continental margin of Australia, occupy a transitional position between cool-water shelf carbonate sediments to the south and more tropical environments to the north. Their existence at the outer limits of the geographical range for coral reef growth is a result of the warm, poleward-flowing Leeuwin Current. Though the modern reefs differ ecologically from tropical reefs, their geological characteristics have been little known until recently. Each of the three island groups in the Abrolhos consists of a central platform of Last Interglacial reefs, about which windward and leeward Holocene reefs have developed asymmetrically. In the Easter Group the subtidal windward reef in the west is ca. 10 m thick and is backed by a leeward-prograding, lagoon sand sheet which is 0 3 m thick. The emergent parts of the leeward reefs in the east consist of an upward-shallowing sequence comprising reef facies, peritidal rudstone facies, and coral rubble storm ridges. This is underlain by over 26 m of Holocene reef facies. Coring and dating of the Holocene reefs (using both U/Th TIMS and 14C methods) in the Easter Group has shown significantly different lithofacies in the windward and leeward reefs, and has allowed reconstruction of Holocene reef growth and sea-level history. Coralline algal bindstones and interbedded coral framestone facies characterise the relatively slow-growing windward Holocene reefs, whereas the fastgrowing leeward reefs consist of coral framestone facies which are dominated by Aeropora. The leeward reefs commenced growth about 10,000 U/Th years ago and the Morley reef grew to 0.3 m above present sea level by 6400 U/Th years B.P., recording a relative high sea-level event. This generated Holocene constructional topography characterised by "blue-hole" terrain. Windward Holocene reef growth commenced after 8200 U/Th years B.P. following erosion of the windward part of the Last Interglacial platform. High wave energy and competition with macroalgae limited coral growth, and the coralline algal-dominated windward reefs grew more slowly to sea level. The Holocene sea-level record provided by dates from the 26 m core of the Morley reef (a "keep-up'" reef) is the first such record from the western continental margin of Australia.

Reef response to Last Interglacial (LIG) sea level and palaeoenvironmental change has been well documented at a limited number of far-field sites remote from former ice sheets. However, the age and development of LIG reefs in the Great Barrier Reef (GBR) remain poorly understood due to their location beneath modern living reefs. Here we report thirty-nine new mass spectrometry U-Th ages from seven LIG platform reefs across the northern, central and southern GBR. Two distinct geochemical populations of corals were observed, displaying activity ratios consistent with either closed or open system evolution. Our closed-system ages (~129-126 ka) provide the first reliable LIG ages for the entire GBR. Combined with our open-system model ages, we are able to constrain the interval of significant LIG reef growth in the southern GBR to between ~129-121 ka. Using age-elevation data in conjunction with newly defined coralgal assemblages and sedimentary facies analysis we have defined three distinct phases of LIG reef development in response to major sea level and oceanographic changes. These phases include: Phase 1 (>129 ka), a shallow-water coralgal colonisation phase following initial flooding of the older, likely Marine Isotope Stage 7 (MIS7) antecedent platform; Phase 2 (~129 ka), a near drowning event in response to rapid sea level rise and greater nutrient-rich upwelling and; Phase 3 (~128-121 ka), establishment of significant reef framework through catch-up reef growth, initially characterised by deeper, more turbid coralgal assemblages (Phase 3a) that transition to shallow-water assemblages following sea level stabilisation (Phase 3b). Coralgal assemblage analysis indicates that the palaeoenvironments during initial reef growth phases (1 and 2) of the LIG were significantly different than the initial reef growth phases in the Holocene.

The recognition of key coral species (KCS) in the geological record, i.e. those that contribute to reef formation and maintenance of coral reef ecosystems, is important for understanding the development and evolution of reef ecosystems and for forecasting their responses to climate change and anthropogenic impacts in the near future. This study examined the contribution to reef formation and maintenance of KCS from Pleistocene and Holocene barrier reefs in New Caledonia, based on analyses of six cores retrieved from three different reefs: Islets Kendec, Amédée, and Bayes. Our results indicate that at least 19 genera and 33 species of corals contributed to reef formation and maintenance during the Holocene in New Caledonia. Among them, Goniastrea retiformis, Isopora palifera, Dipsastraea pallida/speciosa complex, corymbose Acropora sp., massive Porites sp., and encrusting Porites sp. were KCS during the Holocene. This observation suggests that KCS will potentially contribute to the formation and persistence of reefs in the near future under conditions of estimated global sea-level rise of 0.2-0.6 m/100 years. However, the distributions and abundances of these species are currently decreasing. This study emphasizes the need for further research on the restoration and conservation of potential KCS.

We present the first published evidence of uplift along the eastern coast of New Britain, Papua New Guinea based upon 230 Th dating of uplifted Holocene coral reefs. Although uplift rates of the nearby Huon Peninsula are well constrained ($2-3 m/ka), little is known about vertical motion along the eastern margin of New Britain. Based upon relative sea-level curves for Papua New Guinea, present sample elevations, and estimates of paleowater depth of four in-situ Holocene corals we calculate an average uplift rate of 1.6 ± 0.4 m/ka for the southeast coast of New Britain. We suggest underplating of subducted sediment as a possible mechanism for uplift of the reefs.

Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales. To investigate this geological impact, we report the configuration and development of a 4-km-long fringing reef at Punta Maroma along the northeast Yucatan Peninsula. Satellite-derived bathymetry (SDB) shows the crest is setback a uniform distance of 315 ±15 m from a mid-shelf slope break, and the reef-front decreases 50% in width and depth along its length. A 12-core drill transect constrained by multiple 230 Th ages shows the reef is composed of an ∼2-m thick layer of coral clasts that has retrograded 100 m over its back-reef during the last 5.5 ka. These findings are consistent with a hurricane-control model of reef development where large waves trip and break over the mid-shelf slope break, triggering rapid energy dissipation and thus limiting how far upslope individual waves can fragment corals and transport clasts. As SL rises and water depth increases, energy dissipation during wave-breaking is reduced, extending the clast-transport limit, thus leading to reef retrogradation. This hurricane model may be applicable to a large subset of fringing reefs in the tropical Western-Atlantic necessitating a reappraisal of their accretion rates and response to future SL rise.

Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales. To investigate this geological impact, we report the configuration and development of a 4-km-long fringing reef at Punta Maroma along the northeast Yucatan Peninsula. Satellite-derived bathymetry (SDB) shows the crest is setback a uniform distance of 315 ±15 m from a mid-shelf slope break, and the reef-front decreases 50% in width and depth along its length. A 12-core drill transect constrained by multiple 230 Th ages shows the reef is composed of an ∼2-m thick layer of coral clasts that has retrograded 100 m over its back-reef during the last 5.5 ka. These findings are consistent with a hurricane-control model of reef development where large waves trip and break over the mid-shelf slope break, triggering rapid energy dissipation and thus limiting how far upslope individual waves can fragment corals and transport clasts. As SL rises and water depth increases, energy dissipation during wave-breaking is reduced, extending the clast-transport limit, thus leading to reef retrogradation. This hurricane model may be applicable to a large subset of fringing reefs in the tropical Western-Atlantic necessitating a reappraisal of their accretion rates and response to future SL rise.

A database of more than 300 published alpha-counted uranium-series ages has been compiled for coral reef terraces formed by Late Pleistocene high sea-stands. The database was screened to eliminate unreliable age estimates (~-3~Fh/232Th < 20, calcite > 5%) and "those without quoted errors, and a distributed error frequency curve was produced. This curve can be considered as a finite mixture model comprising k component normal distributions each with a weighting cc By using an expectation maximising algorithm, the mean and standard deviation of the component distributions, each corresponding to a high sea level event, were estimated. Eight high sea-stands with mean and standard deviations of 129.0 + 33.0, 123.0 + 13.0, 102.5 + 2.0, 81.5 + 5.0, 61.5 + 6.0, 50.0 + 1.0, 40.5 + 5.0 and 33.0 + 2.5 ka were resolved. The standard deviations are generally larger than the values quoted for individual age estimates. Whilst this may be due to diagenetic effects, especially for the older corals, it is argued that in many cases geological evidence clearly indicates that the high stands are multiple events, often not resolvable at sites with low rates of uplift. The uranium-series dated coral-reef terrace chronology shows good agreement with independent chronologies derived for Antarctic ice cores, although the resolution for the latter is better. Agreement with orbitally-tuned deep-sea core records is also good, but it is argued that Isotope Stage 5e is not a single event, as recorded in the cores, but a multiple event spanning some 12 ka. The much earlier age for Isotope Stage 5e given by Winograd et al. (1988) is not supported by the coral reef data, but further mass-spectrometric uranium-series dating is needed to permit better chronological resolution.

Uplifted coral terraces at Huon Peninsula, Papua New Guinea, preserve a record of sea level, sea-surface temperature, and salinity from the penultimate deglaciation. Remnants have been found of a shallow-water reef that formed during a pause, similar to the Younger Dryas, in the penultimate deglaciation at 130,000 ± 2000 years ago, when sea level was 60 to 80 meters lower than it is today. Porites coral, which grew during this period, has oxygen isotopic values and strontium/calcium ratios that indicate that sea-surface temperatures were much cooler (22° ± 2°C) than either Last Interglacial or present-day tropical temperatures (29° ± 1°C). These observations provide further evidence for a major cooling of the equatorial western Pacific followed by an extremely rapid rise in sea level during the latter stages of Termination II.

Where multiple cores have been recovered from a single reef, growth models can be constructed. The reef growth model of Marshall and Davies (1982) suggests that following Pleistocene substrate inundation c. 8 ka, high-energy coral head facies and lower energy branching coral facies aggraded on the windward and leeward sides, respectively, with both initially lagging behind sea-level rise and the windward facies attaining modern sea-level sooner than the leeward after sea-level began to stabilise. Once sea-level was attained on the windward margin, progradation was directed primarily towards the backreef/lee. However, Hopley et al. (2007) noted from sparse data, that many GBR reefs evolved differently. Heron Reef affords observations of reef framework in large (m+) blocks dredged from the reef flat on the western end during enlargement of the boat harbor in 1988. These blocks provide good examples of the in situ coral framework. This paper proposes to place the Heron Reef framework and limited coring data in the context of regional geology of the southern Great Barrier Reef Province (GBRP). Regional Setting Heron Reef, in the southern GBRP had its geology outlined by Jell and Flood (1978) and the origin and evolution of the GBR have been reviewed by Davies (2011). The GBRP includes eastern Queensland's continental shelf that has been occupied or influenced by reefs and reef-derived sediments at any time since the initiation of reef growth. It represents the western margin of the Northeast Australian Carbonate Platform System, which also includes the reef provinces of the Gulf of Papua and the Eastern, Queensland, and Marion plateaus (Davies et al., 1988; Figure 1). The offshore plateaus and intervening troughs appear to be modified and subsided continental crust that originated from late Cretaceous-Paleogene rifting of the northeastern Australian Plate (Symonds et al., 1983). At 2,300 km long, from Bramble and Anchor cays in the Gulf of Papua (latitude 9 o 15'S) to S of Lady Elliot Island (latitude 24 o 10'S) and covering 265,000 km 2 , the GBRP is the largest reefal and carbonate-siliclastic shelf system in the present oceans, and is comparable in size to some of the large carbonate platforms in the geological record. The continental shelf is mostly a shallow (0-90 m, average 40 m), partially rimmed, high-energy platform, sloping gently (<1-4 m/km) from the coast to the shelf edge and deepening southward. Apart from the latter and the N being wetter than the S, there is little latitudinal variation. It is narrowest off Cooktown broadening to the N across Torres Strait into the Gulf of Papua and to the S off Broad Sound where the reefs occupy only mid to outer shelf areas. The shelf narrows considerably at its extreme southern margin where it is embayed by the Capricorn Channel. Throughout the length of the Heron Island has been the focal point for research on the southern Great Barrier Reef Province for the last 80 years. Heron Reef is an excellent example of a lagoonal platform reef with a sand cay developed on its leeward end, displaying typical reef morphological, sedimentological and ecological zonations allowing comparison of their windward and leeward development. Limited subsurface data indicate that the total reef section is only 150 m thick, consisting of stacked limestone packages, with a gently eastward sloping solution disconformity delineating the base of c. 15 m of Holocene reef growth. Holocene reef growth does not appear to fit the "classical" model, with evidence of much progradation on the windward margin relative to the associated leeward margin. Large dredged blocks of reefal material provide new data on the abundance of in situ framework in much of the reef and the importance of microbialite in the unification process.

Uplifted late Quaternary coral reefs on the island of Barbados record folding of the emergent crest of the Lesser Antilles accretionary prism (Barbados Ridge complex) since ca. 1 Ma. Three northeast-striking folds are defined by systematic changes in altitudes in the crest of First High Cliff, a mostly constructional reef terrace of about 125 ka, and Second High Cliff, a partially erosional reef terrace of about 500 ka. The folds have wavelengths of 6 to 8 km and fold axes extend about 10 km. The largest anticline rises to the northeast, where it has been breached by erosion exposing highly deformed Eocene to lower Miocene rocks of the Scotland District. Uplift rates based on heights of the last interglacial First High Cliff range from 0.07 to 0.44 mm/yr. Quaternary folding on Barbados indicates that the crest of the accretionary prism continues to be an active fold belt undergoing northwest-southeast shortening.

Previous drilling through submerged fossil coral reefs has greatly improved our understanding of the general pattern of sealevel change since the Last Glacial Maximum, however, how reefs responded to these changes remains uncertain. Here we document the evolution of the Great Barrier Reef (GBR), the world's largest reef system, to major, abrupt environmental changes over the past 30 thousand years based on comprehensive sedimentological, biological and geochronological records from fossil reef cores. We show that reefs migrated seaward as sea level fell to its lowest level during the most recent glaciation (~20.5-20.7 thousand years ago (ka)), then landward as the shelf flooded and ocean temperatures increased during the subsequent deglacial period (~20-10 ka). Growth was interrupted by five reef-death events caused by subaerial exposure or sea-level rise outpacing reef growth. Around 10 ka, the reef drowned as the sea level continued to rise, flooding more of the shelf and causing a higher sediment flux. The GBR's capacity for rapid lateral migration at rates of 0.2-1.5 m yr −1 (and the ability to recruit locally) suggest that, as an ecosystem, the GBR has been more resilient to past sea-level and temperature fluctuations than previously thought, but it has been highly sensitive to increased sediment input over centennial-millennial timescales.

Integrated Ocean Drilling Program (IODP) Expedition 325, designed to investigate the fossil reefs on the shelf edge of the Great Barrier Reef, was the fourth expedition to utilize a mission-specific platform and was conducted by the European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO). The objectives of Expedition 325 were to establish the course of sea level change, define sea-surface temperature variations, and analyze the impact of these environmental changes on reef growth and geometry for the region over the period of 20-10 ka. To meet these objectives, a succession of fossil reef structures preserved on the shelf edge seaward of the modern barrier reef were cored from a dynamically positioned vessel in February-April 2010. A total of 34 boreholes across 17 sites were cored in depths ranging from 42.27 to 167.14 meters below sea level (lowest astronomical tide taken from corrected EM300 multibeam bathymetry data). Borehole logging operations in four boreholes provided continuous geophysical information about the drilled strata. The cores were described during the Onshore Science Party (OSP) at the IODP Bremen Core Repository (Germany) in July 2010, where minimum and some standard measurements were made. Preliminary postcruise dating of core catcher samples and initial observations of the cores made during the OSP confirm that coral reef material ranging in age from >30,000 to 9,000 calendar years before present (years before 1950 AD) was recovered during Expedition 325. Further postcruise research on samples taken during the OSP is expected to fulfill the objectives of the expedition.

The history of sea level and sea-surface temperature (SST) variation associated with the last deglaciation is of prime interest to understanding dynamics of large ice sheets and their effects on Earth's isostasy. So far, the only sea level record that encompasses the whole deglaciation is based on offshore drilling of Barbados coral reefs that overlie an active subduction zone, implying that the apparent sea level record may be biased by tectonic movements. This proposal seeks to establish the course and effects of the last deglaciation in a reef setting that developed in a tectonically inactive area at sites located far away from glaciated regions in Tahiti (French Polynesia). At each site, we propose to sample a transect of several offshore drill holes using a dynamically positioned drilling vessel. The study will have three major objectives. The first objective will be to reconstruct the deglaciation curve for the period 20.00-10.00 ka in order to establish the minimum sea level during the Last Glacial Maximum (LGM) and to assess the validity, timing, and amplitude of meltwater pulses (so-called meltwater pulse 1A and 1B [MWP-1A and MWP-1B] events; ~13.80 and 11.30 ka, respectively) that are thought to have disturbed the general thermohaline oceanic circulation and, hence, global climate. Second, we will establish the SST variation accompanying the transgression at each transect. These data will allow us to examine the impact of sea level changes on reef growth, geometry, and biological makeup, especially during reef drowning events, and will help improve the modeling of reef development. The third major objective will be to identify and establish patterns of short-term paleoclimatic changes that are thought to have punctuated the transitional period between presentday climatic conditions following the LGM. We propose to quantify the variations of SSTs based on high-resolution isotopic and trace element analyses on massive coral colonies. When possible, we will try to identify specific climatic phenomena such as the El Niño-Southern Oscillation (ENSO) in the time frame prior to 10.00 ka.

So far, the most complete and accurate sea-level record that encompassed the period between the Last Glacial Maximum and the present day is based on cores drilled offshore the Barbados coral reef [1,2]. That record suggests a non-monotonous sea level rise punctuated by two dramatic accelerations, the MWP1-A and MWP1-B events, centred at ∼14,000 and ∼11,300 cal. yr BP respectively [3]. However, the occurrence, the hemispheric origin as well as the exact relationship between those events and the global climatic evolution remains enigmatic and controversial.

Uplifted reefs due to being important palaeoclimate archives and a rich source of information on past physical and geochemical changes globally have become the centre of marine research. The uplifted fossil Quaternary coral communities of Jiwani and Gwadar are perfect places to study the palaeoclimatic and geological changes that have shaped the Balochistan coast. Studies on the palaeodiversity of corals along the Makran coast of Pakistan are lacking. In the present study, the samples collected using line intercept method from four uplifted sites (Balochistan coast: one at Gwadar and three at Jiwani) were analysed. The relative distribution and diversity of scleractinian fossil corals was determined, and the factors responsible for coral decline along Pakistan coast were compared with modern coral distribution and diversity. A total of 48 fossil coral species were recorded in nine families and 22 genera. High coral diversity was recorded in the uplifted landward sites of Jiwani and Gwadar headland. Terraces close to the shore at Jiwani had lower diversity. The corals seem to be Quaternary: most likely Pleistocene to Holocene. The modern fauna lacks many species recorded in the fossil community, thus suggesting a faunal turnover in diversity and redistribution of coral fauna which may be linked with past geological events and increasing anthropogenic pressure.

Water availability is the main limiting factor in arid soils; however, few studies have examined the effects of drying and rewetting on nitrifiers from these environments. The effect of water availability on the diversity of ammonia-oxidizing bacteria (AOB) and archaea (AOA) from a semiarid soil of the Chilean sclerophyllous matorral was determined by microcosm assays. The addition of water every 14 days to reach 60% of the WHC significantly increased nitrate content in rewetted soil microcosms (p < 0.001). This stimulation of net nitrification by water addition was inhibited by acetylene addition at 100 Pa. The composition of AOA and AOB assemblages from the soils microcosms was determined by clone sequencing of amoA genes (A-amoA and B-amoA, respectively), and the 16S rRNA genes specific for β-proteobacteria (beta-amo). Sequencing of beta-amo genes has revealed representatives of Nitrosomonas and Nitrosospira while B-amoA clones consisted only of Nitrosospira sequences. Furthermore, all clones from the archaeal amoA gene library (A-amoA) were related to "mesophilic Crenarchaeota" sequences (actually, reclassified as the phylum Thaumarchaeota). The effect of water availability on both microbial assemblages structure was determined by T-RFLP profiles using the genetic markers amoA for archaea, and beta-amo for bacteria. While AOA showed fluctuations in some T-RFs, AOB structure remained unchanged by water pulses. The relative abundance of AOA and AOB was estimated by the Most Probable Number coupled to Polymerase Chain Reaction (MPN-PCR) assay. AOB was the predominant guild in this soil and higher soil water content did not affect their abundance, in contrast to AOA, which slightly increased under these conditions. Therefore, these results suggest that water addition to these semiarid soil microcosms could favor archaeal contribution to ammonium oxidation.

Problems in Palaeoclimatology Site characteristics Geological setting of materials studied Tectonic implications around northeast Huon General description of the raised terraces Analytical techniques Mass spectrometry measurements of 1Bo/ 1 6o and 13c/ 12 c ratios using a single collector and matched molecular flow leaks Reporting of oxygen and carbon isotope data in this study• Field and laboratory criteria for selecting reef material samples Collection and preparation of water samples for isotopic determinations Preparation of carbon dioxide gas for 1 Bo;l6o and 1 3c/ 12 c ratio measurements Preparation of water samples for lBo/ 16 0 and D/H ratio measurement Analytical techniques other than stable

We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater d 234 U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the d 234 U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222 Rn concentrations and d 234 U compositions, likely due to variations in subglacial residence time. Locations with high d 234 U have the potential to increase proximal seawater d 234 U. To better understand the impact of bulk glacial melt on global seawater d 234 U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater d 234 U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.

Understanding of global sea-level changes and coral reef development is poorly constrained during Marine Isotope Stage 3 (MIS 3; ~ 60 to 30 ka). Australia's North West Shelf (NWS), at depths of ~ 50 to 120 m below present sea-level (mbsl), represents an ideal natural laboratory to address these knowledge gaps. In this study, the authors investigate a unique suite of sea-bed rock drill (PROD) cores recovered as part of a geotechnical survey from the NWS ~ 150 km southeast of Ashmore Reef. Twenty cores, penetrating to 28 m below sea floor, were collected from the top of the now drowned platform complex in similar water depths (74.8 to 81.6 mbsl), forming two transects ~ 17 km apart. High-resolution 3D seismic and multibeam bathymetry data reveal three distinct, multigenerational platforms that are rimmed by smaller reef terraces and bisected by deeper channels, placing the core transects into a robust, regional geomorphic context that includes a succession of linear palaeo-shorelines and tidal-estuarine channel systems on the adjacent shelf between ~ 90 to 110 mbsl. The authors have completed detailed logging, highspatial resolution hyperspectral scanning, petrologic, mineralogic and sedimentary facies analysis of these cores, including a precise palaeoenvironmental reconstruction based on coral, algal and larger benthic foraminifera assemblages; and extensive radiometric dating. The authors have observed a complex suite of

Contents 1 Introduction 2 Geologic setting 3 Previous studies 4 Methods 5 Results 5.1 Lithology of unit Q 1 5.2 Lithology of unit Q2 5.3 Lithology of unit Q3 5.4 Lithology of unit Q4 5.5 Lithology of unit QSe 5.6 Lithology of post-Q5e units 5.7 Diagenesis of Q units 5.8 Chronology 5.9 Paleokarst features 5.10 Quartz in the Key Largo Limestone 5.11 Florida Bay bedrock 5.12 Paleotopography and platform tiring 6 Discussion 6.1 Variability of facies 6.2 QI and Q2: early facies evolution 6.3 Q3: flourishing reef facies 6.4 Q4 and Q5e: lagoonal/patch reef facies 6.5 Post-Q5e: shelf-margin wedge 6

Coral reef terraces are one of the best recorders of relative sea-level changes during the last glacial cycle. Thus far, knowledge of relative sea-level record based on coral reefs during the marine Oxygen Isotope Stage (OIS) 3 has been limited to studies of the Huon Peninsula, Papua New Guinea. High-precision a a-spectrometric 230 Th/ 234 U dating demonstrated an offlapping sequence of five coral reef complexes, ages of which are B66, B64, B62, B55 and B52 ka, in the northern part of Kikai Island, central Ryukyus of Japan. Interstadial reefs, characterized by deepening-upward sequences of coral assemblages, recorded three hemicycles from transgression to highstand at B52, B62, and B66 ka, during which these reefs were drowned. These highstands in the relative sealevel record can be correlated with the eustatic record reconstructed from the Huon reef terraces and with the interstadials 14, 18, and 19 of the GISP 2 oxygen isotope record. This consistency confirms the Huon sea-level record of OIS 3 and implies that the eustatic sea level responded to the millennial-scale climate changes even during the glacial period of OIS 4.

Coral reef is one of the best archives of a climate change. The reefs record the condition of environment where they developed. Indonesia as a tropical country has abundant coral reefs from Tertiary to Recent. The ancient reefs are commonly found along the coast and they form terraces. This research is located at the Selayar limestone of Bulukumba Regency, South Sulawesi. The objective of this research is to define paleoclimate change based on the coral development and sea level fluctuation. Sample collection was done by applying five intersect lines perpendicular to the cliff. Petrographic analyses of fossils, and microfacies study as well as the sea level fluctuation were analyzed by studying organism, reef development, and morphology. This article is focused on the sea level fluctuation analysis. There are three stages of the reef development and sea level fluctuation. It was initiated within a protected shallow marine to a reef front slope unconformably overlying siliciclastic rock. The second period of the reef development is characterized by the growing of branching, delicate, robust, and massive corals associating giant Tridacna sp. The third period is the formation of bafflestone delicate branching coral and robust branching corals. Following the Pleistocene reef development three beach abrasions (notches) were identified indicating the sea level fluctuation. Beach abrasions occurred during the Pleistocene reef development as the first notch. The second notch occurred at the reef crest and back reef during the first sea level fall and finally the recent sea level as the third notch.

New core and seismic data suggest that widespread reef building started on Lang Bank by 8,900 CalBP and was dominated by Acropora palmata for the next three millennia. Accretion rates averaged 5.81 m ky-1 , a rate that was sufficient for reefs to keep pace with rising sea level on the bank throughout their history. Seismic data show a deep platform interior that was flooded well in advance of reef building along the elevated rim. As a result, those reefs were buffered from sediment stress by their higher positions and active water flow to the west. A. palmata disappeared from the shallow margin by 6,350 yr ago, and reef building on Lang Bank largely ceased by 5,035 CalBP. The reasons for these dramatic events are unclear. Water depth over the reefs was generally shallower than when they started to build, and sea level was slowing dramatically. The new data described here show that reefs flourished on Lang Bank throughout the hiatus suggested by earlier studies (10-7 kyrs BP), and the ultimate demise of shelf-edge reefs is clearly not associated with either poor water quality or sudden sea-level rise. In addition, accretion rates from eastern St. Croix and throughout the Caribbean were well below the high values (C10 m ky-1) that have been widely assumed. These data collectively argue against models that require extreme environmental or oceanographic phenomena to drown reefs on Lang Bank where reef building was too fast to be outpaced by Holocene sea-level rise. This also bears on more generalized Caribbean models that depend on the presumed reef history on eastern St. Croix.

In this work, radiochemical results obtained by spectrometry on 80 unrecrystallized fossil coral samples from the Egyptian shoreline of the northwestern Red Sea are presented and discussed. The coral samples were collected in Egypt from the emerged 5e coral reef terraces over 500 km from The Ras Gharib-Ras Shukeir depression (28 • 10) in the north to Wadi Lahami (north of Ras Banas, 24 • 10) in the south. The statistical description of radiochemical results (concentrations of U and Th radioisotopes, 234 U/ 238 U activity ratios and ages) obtained on a great number of coral samples showed that it is possible to establish methodological criterions which could be used to validate the measured ages before confronting them to the geological context of sampling sites. The obtained results confirm that the unrecrystallized corals (232 Th < 3%) constitute the reliable means of determining the timing of Pleistocene sea-level fluctuations in the past. A few number of measured younger ages could be explain as a result of a rejuvenation due to latter addition of a "younger" uranium to the initial stock entered just after coral death. The obvious rejuvenation observed and confirmed is due to a recent cementation of aragonitic deposit on the fossil coral. 238 U varies between 2.2 and 4.9 ppm around an average of 3.18 ± 0.65 ppm. 234 U/ 238 U activity ratios are between 1.08 and 1.28 with an averaged value of 1.164 ± 0.016 which exceeds that of present day sea water but which is in agreement with the ratio of 1.16 measured by a precise mass spectrometry in many Pleistocene coral samples. Except three samples dated at least 100 ka, the radiochemical age of 5e coral samples vary between 108 and 131 ka with an average value of 122.2 ka and a standard deviation of 4.3 ka. Except for samples from the Zeit area, the reef terrace is between 2 and 6 m above the present sea level. This position is similar to the highest sea level from the last interglacial according to the glacio-isostatic rebound calculated for stable regions. This work proves that the large tectonic motions which affected the studied area after the Oligocene ceased after at least the last interglacial period.