(Supplement Table S2) Results of 230Th/U-dating

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

Pollen record and dating of a sediment profile from Ahlequellmoor in Germany

A pollen diagram from the Ahlequellmoor in the Solling area shows the history of vegetation and settlement over the last 7,800 years. In the early Atlantic period mixed deciduous forest with mainly Tilia together with Ulmus and Quercus grew in the area. In the late Atlantic period Quercus became most abundant. Fagus spread in the Sub-boreal period at about 2700 B.C. Since ca. 900 B.C. the Solling was covered by beech forests with some oak. In prehistoric times woodland grazing is indicated. Only in Medieval times are two settlements in the vicinity of the Ahlequellmoor reflected in the pollen diagram. The earlier one is dated to about A.D. 750-1020, and may be connected with the former Monastery of Hethis, which is thought to have existed close to the fen from A.D. 815 to 822. The second Medieval settlement dates to the 11th-12th century. The large-scale woodland destruction of late Medieval and modern times is not clearly visible. The silvicultural measures of the last 200 years are reflected by increasing values of spruce and grassland taxa.

Radiocarbon dating on four sediment profiles from Bunger Hills, East Antarctica

Radiocarbon dating was carried out on the total organic carbon of 19 lacustrine and marine sediment samples from the Bunger Hills. The results indicate that radiocarbon contamination is negligible throughout two sediment sequences from a fresh water lake. In contrast, two sequences from marine basins are irregularly influenced by the Antarctic Marine Reservoir Effect, which today amounts to more than 1000 years, depending on the degree of dilution with meltwater. All sediments were deposited during Holocene time.

SHRIMP U-Pb dating of high-grade migmatites and related magmatites from Northwestern Oates Land, East Antarctica

High- to very-high-grade migmatitic basement rocks of the Wilson Hills area in northwestern Oates Land (Antarctica) form part of a low-pressure high-temperature belt located at the western inboard side of the Ross-orogenic Wilson Terrane. Zircon, and in part monazite, from four very-high grade migmatites (migmatitic gneisses to diatexites) and zircon from two undeformed granitic dykes from a central granulite-facies zone of the basement complex were dated by the SHRIMP U-Pb method in order to constrain the timing of metamorphic and related igneous processes and to identify possible age inheritance. Monazite from two migmatites yielded within error identical ages of 499 +/- 10 Ma and 493 +/- 9 Ma. Coexisting zircon gave ages of 500 +/- 4 Ma and 484 +/- 5 Ma for a metatexite (two age populations) and 475 +/- 4 Ma for a diatexite. Zircon populations from a migmatitic gneiss and a posttectonic granitic dyke yielded well-defined ages of 488 +/- 6 Ma and 482 +/- 4 Ma, respectively. There is only minor evidence of age inheritance in zircons of these four samples. Zircon from two other samples (metatexite, posttectonic granitic dyke) gave scattered 206Pb-238U ages. While there is a component similar in age and in low Th/U ratio to those of the other samples, inherited components with ages up to c. 3 Ga predominate. In the metatexite, a major detrital contribution from 545 - 680 Ma old source rocks can be identified. The new age data support the model that granulite- to high-amphibolite-facies metamorphism and related igneous processes in basement rocks of northwestern Oates Land were confined to a relatively short period of time of Late Cambrian to early Ordovican age. An age of approximately 500 Ma is estimated for the Ross-orogenic granulite-facies metamorphism from consistent ages of monazite from two migmatites and of the older zircon age population in one metatexite. The variably younger zircon ages are interpreted to reflect mineral formation in the course of the post-granulite-facies metamorphic evolution, which led to a widespread high-amphibolite-facies retrogression and in part late-stage formation of ms+bi assemblages in the basement rocks and which lasted until about 465 Ma. The presence of inherited zircon components of latest Neoproterozoic to Cambrian age indicates that the high- to very-grade migmatitic basement in northwestern Oates Land originated from clastic series of Cambrian age and, therefore, may well represent the deeper-crustal equivalent of lower-grade metasedimentary series of the Wilson Terrane.

Benthic foraminiferal record and age dating of sediment cores from the Gullmar Fjord at the west coast of Sweden

A high-resolution study of benthic foraminiferal assemblages was performed on a ca. eight metre long sediment core from Gullmar Fjord on the west coast of Sweden. The results of 210Pb- and AMS 14C-datings show that the record includes the two warmest climatic episodes of the last 1500 years: the Medieval Warm Period (MWP) and the recent warming of the 20th century. Both periods are known to be anomalously warm and associated with positive NAO winter indices. Benthic foraminiferal successions of both periods are compared in order to find faunal similarities and common denominators corresponding to past climate changes. During the MWP, Adercotryma glomerata, Cassidulina laevigata and Nonionella iridea dominated the assemblages. Judging from dominance of species sensitive to hypoxia and the highest faunal diversity for the last ca. 2400 years, the foraminiferal record of the MWP suggests an absence of severe low oxygen events. At the same time, faunas and d13C values both point to high primary productivity and/or increased input of terrestrial organic carbon into the fjord system during the Medieval Warm Period. Comparison of the MWP and recent warming revealed different trends in the faunal record. The thin-shelled foraminifer N. iridea was characteristic of the MWP, but became absent during the second half of the 20th century. The recent Skagerrak-Kattegat fauna was rare or absent during the MWP but established in Gullmar Fjord at the end of the Little Ice Age or in the early 1900s. Also, there are striking differences in the faunal diversity and absolute abundances of foraminifera between both periods. Changes in primary productivity, higher precipitation resulting in intensified land runoff, different oxygen regimes or even changes in the fjord's trophic status are discussed as possible causes of these faunal differences.

Location and ages of terrestrial peatlands located on continental shelves and in coastal sediments

This synthesis dataset contains records of freshwater peat and lake sediments from continental shelves and coastal areas. Information included is site location (when available), thickness and description of terrestrial sediments as well as underlying and overlying sediments, dates (when available), and references.