Miocene microflora and palaeoclimatic estimates of the Stetten section (Austria)

Pollen analyses have been proven to possess the possibility to decipher rapid vegetational and climate shifts in Neogene sedimentary records. Herein, a c. 21-kyr-long transgression-regression cycle from the Lower Austrian locality Stetten is analysed in detail to evaluate climatic benchmarks for the early phase of the Middle Miocene Climate Optimum and to estimate the pace of environmental change. Based on the Coexistence Approach, a very clear signal of seasonality can be reconstructed. A warm and wet summer season with c. 204-236 mm precipitation during the wettest month was opposed by a rather dry winter season with precipitation of c. 9-24 mm during the driest month. The mean annual temperature ranged between 15.7 and 20.8 °C, with about 9.6-13.3 °C during the cold season and 24.7-27.9 °C during the warmest month. In contrast, today's climate of this area, with an annual temperature of 9.8 °C and 660 mm rainfall, is characterized by the winter season (mean temperature: -1.4 °C, mean precipitation: 39 mm) and a summer mean temperature of 19.9 °C (mean precipitation: 84 mm). Different modes of environmental shifts shaped the composition of the vegetation. Within few millennia, marshes and salt marshes with abundant Cyperaceae rapidly graded into Taxodiaceae swamps. This quick but gradual process was interrupted by swift marine ingressions which took place on a decadal to centennial scale. The transgression is accompanied by blooms of dinoflagellates and of the green alga Prasinophyta and an increase in Abies and Picea. Afterwards, the retreat of the sea and the progradation of estuarine and wetland settings were a gradual progress again. Despite a clear sedimentological cyclicity, which is related to the 21-kyr precessional forcing, the climate data show little variation. This missing pattern might be due to the buffering of the precessional-related climate signal by the subtropical vegetation. Another explanation could be the method-inherent broad range of climate-parameter estimates that could cover small scale climatic changes.

Sediment composition and sedimentation rates of four Holes in ODP Leg 166

To date, work on the Great Bahama Bank's western, leeward margin has centred chiefly on seismic-scale expressions of carbonate sequences and systems tracts. However, periplatform, slope sediments also exhibit very well developed cyclicity on scales of decimetres to several metres. It is these small-scale, high-frequency cycles within the larger-scale facies successions of the Quaternary which form the main topic of this paper. Previous studies have shown that the small-scale cycles correlate to the orbitally forced, high-frequency sea-level changes. Therefore these cycles should indicate how sea level has affected the slope development and thus platform-margin evolution during this period. Through detailed, high-resolution sequence stratigraphy of the Great Bahama Bank's leeward margin, obtained via delta18O isotope and mineralogical (XRD) analyses, confined by U/Th dating and nannofossil bioevents, a greater understanding of the bedding geometries within the Pleistocene-Holocene seismic sequences and clues as to the nature of the slope development has been achieved. The high-resolution seismic profiles indicate that since the Plio-Pleistocene change in geometry, in which the Great Bahama Bank developed into a rimmed platform, continued steepening and subsequent progradation of the leeward margin has typified slope development during the Quaternary, which is described as an accretionary slope. However, on the basis of our observations we conclude that only the early to lower middle Pleistocene section (isotope stages 45-20) and the Holocene (isotope stage 1) of the leeward margin is accretionary. This indicates that a degree of erosion and/or by-passing has occurred on the leeward margin since the lower middle Pleistocene (isotope stage 19). During the first part of this period (isotope stages 19-12) erosion and/or by-passing occurred in the middle to lower slope regions and toe-of-slope. By the end of the upper middle to late Pleistocene phase (isotope stages 11-2) erosion also occurred on the upper slope. This erosion by currents at the toe-of-slope and oversteepening of the upper and middle slopes have led to back-cutting upslope and resulted in the progressive retreat of the toe-of-slope towards the platform to the east. However, the rise in sea level since the Last Glacial Maximum to its present-day level has allowed high productivity on the platform top during the Holocene and the deposition of a thick sediment wedge on the slope and sedimentation across the entire leeward flanks. This has led to the redevelopment of an accretionary slope and continued westward progradation of the Great Bahama Bank's western, leeward margin.

Age and strontium isotope composition for Cretaceous in DSDP Hole 74-525

Firm stratigraphic correlations are needed to evaluate the global significance of unconformity bounded units (sequences). We correlate the well-developed uppermost Campanian and Maestrichtian sequences of the New Jersey Coastal Plain to the geomagnetic polarity time scale (GPTS) by integrating Sr-isotopic stratigraphy and biostratigraphy. To do this, we developed a Maestrichtian (ca. 73-65 Ma) Sr-isotopic reference section at Deep Sea Drilling Project Hole 525A in the southeastern Atlantic Ocean. Maestrichtian strata can then be dated by measuring their 87Sr/86Sr composition, calibrating to the GPTS of S. C. Cande and D. V. Kent (1993, personal commun.), and using the equation Age (Ma) = 37326.894-52639.89 (87Sr/86Sr). Sr-stratigraphic resolution for the Maestrichtian is estimated as +-1.2 to +-2 m.y. At least two unconformity-bounded units comprise the uppermost Campanian to Maestrichtian strata in New Jersey. The lower one, the Marshalltown sequence, is assigned to calcareous nannofossil Zones CC20/21 (~NC19) and CC22b (~NC20). It ranges in age from ~74.1 to 69.9 Ma based on Sr-isotope age estimates. The overlying Navesink sequence is assigned to calcareous nannoplankton Zones CC25-26 (~NC21-23); it ranges in age from 69.3 to 65 Ma based on Sr-isotope age estimates. The upper part of this sequence, the Tinton Formation, has no calcareous planktonic control; Sr-isotopes provide an age estimate of 66 +- 1.2 Ma (latest Maestrichtian). Sequence boundaries at the base and the top of the Marshalltown sequence match boundaries elsewhere in the Atlantic Coastal Plain (Owens and Gohn, 1985) and the inferred global sea-level record of Haq et al. (1987); they support eustatic changes as the mechanism controlling depositional history of this sequence. However, the latest Maestrichtian record in New Jersey does not agree with Haq et al. (1987); we attribute this to correlation and time-scale differences near the Cretaceous/Paleogene boundary. High sedimentation rates in the latest Maestrichtian of New Jersey (Shrewsbury Member of the Red Bank Formation and the Tinton Formation) suggest tectonic uplift and/or rapid progradation during deposition of the highstand systems tract.

Radar profiles from South Shetland Islands/Western Antarctic Peninsula

The sedimentary architecture of polar gravel-beach ridges is presented and it is shown that ridge internal geometries reflect past wave-climate conditions. Ground-penetrating radar (GPR) data obtained along the coasts of Potter Peninsula (King George Island) show that beach ridges unconformably overlie the prograding strand plain. Development of individual ridges is seen to result from multiple storms in periods of increased storm-wave impact on the coast. Strand-plain progradation, by contrast, is the result of swash sedimentation at the beach-face under persistent calm conditions. The sedimentary architecture of beach ridges in sheltered parts of the coast is characterized by seaward-dipping prograding beds, being the result of swash deposition under stormy conditions, or aggrading beds formed by wave overtopping. By contrast, ridges exposed to high-energy waves are composed of seaward- as well as landward-dipping strata, bundled by numerous erosional unconformities. These erosional unconformities are the result of sediment starvation or partial reworking of ridge material during exceptional strong storms. The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches. The frequency of ridge building ranges from decades in the low-energy settings up to 1600 years under high-energy conditions. Beach ridges in the study area cluster at 9.5, 7.5, 5.5, and below 3.5 m above the present-day storm beach. Based on radiocarbon data, this is interpreted to reflect distinct periods of increased storminess and/or shortened annual sea-ice coverage in the area of the South Shetland Islands for the times around 4.3, c. 3.1, 1.9 ka cal BP, and after 0.65 ka cal BP. Ages further indicate that even ridges at higher elevations can be subject to later reactivation and reworking. A careful investigation of the stratigraphic architecture is therefore essential prior to sampling for dating purposes.

Middle Miocene mineralogical events of Marion Plateau, northeast of Australia

Three ODP sites located on the Marion Plateau, Northeast Australian margin, were investigated for clay mineral and bulk mineralogy changes through the early to middle Miocene. Kaolinite to smectite (K/S) ratios, as well as mass accumulation rates of clays, point to a marked decrease in accumulation of smectite associated with an increase in accumulation of kaolinite starting at ~15.6 Ma, followed by a second increase in accumulation of kaolinite at ~13.2 Ma. Both of these increases are correlative to an increase in the calcite to detritus ratio. Comparison of our record with published precipitation proxies from continental Queensland indicates that increases in kaolinite did not correspond to more intense tropical-humid conditions, but instead to periods of greater aridity. Three mechanisms are explored to explain the temporal trends in clay on the Marion Plateau: sea-level changes, changes in oceanic currents, and denudation of the Australian continent followed by reworking and eolian transport of clays. Though low mass accumulation rates of kaolinite are compatible with a possible contribution of eolian material after 14 Ma, when Australia became more arid, the lateral distribution of kaolinite along slope indicates mainly fluvial input for all clays and thus rules out this mechanism as well as oceanic current transport as the main controls behind clay accumulation on the plateau. We propose a model explaining the good correlation between long-term sea-level fall, decrease in smectite accumulation, increase in kaolinite accumulation and increase in carbonate input to the distal slope locations. We hypothesize that during low sea level and thus periods of drier continental climate in Queensland, early Miocene kaolinite-rich lacustrine deposits were being reworked, and that the progradation of the heterozoan carbonate platforms towards the basin center favored input of carbonate to the distal slope sites. The major find of our study is that increase kaolinite fluxes on the Queensland margin during the early and middle Miocene did not reflect the establishment of a tropical climate, and this stresses that care must be taken when reconstructing Australian climate based on deep-sea clay records alone.

Sedimentological and palynological analysis of sediment cores from the northeastern Vietnamese Mekong River Delta

Three radiocarbon-dated sediment cores from the northeastern Vietnamese Mekong River Delta have been analysed with a multiproxy approach (grain size, pollen and spores, macro-charcoal, carbon content) to unravel the palaeoenvironmental history of the region since the mid Holocene. During the mid-Holocene sea-level highstand a diverse, zoned and widespread mangrove belt (dominated by Rhizophora) covered the extended tidal flats. The subsequent regression and coeval delta progradation led to the rapid development of a back-mangrove community dominated by Ceriops and Bruguiera but also represented locally by e.g. Kandelia, Excoecaria and Phoenix. Along rivers this community seems to have endured even when the adjoining floodplain had already shifted to freshwater vegetation. Generally this freshwater vegetation has a strong swamp signature but locally Arecaceae, Fabaceae, Moraceae/Urticaceae and Myrsinaceae are important and mirror the geomorphological diversity of the delta plain. The macro-charcoal record implies that natural burning of vegetation occurred throughout the records, however, the occurrence of the highest amounts of macro-charcoal particles is linked with modern human activity.

Benthic foraminifera and stable isotope record of ODP Leg 182 sites

Cores from Sites 1129, 1131, and 1132 (Ocean Drilling Program (ODP) Leg 182) on the uppermost slope at the edge of the continental shelf in the Great Australian Bight reveal the existence of upper Pleistocene bryozoan reef mounds, previously only detected on seismic lines. Benthic foraminiferal oxygen isotope data for the last 450,000 years indicate that bryozoan reef mounds predominantly accumulated during periods of lower sea level and colder climate since stage 8 at Sites 1129 and 1132 and since stage 4 at the deeper Site 1131. During glacials and interstadials (stages 2-8) the combination of lowered sea level, increased upwelling, and absence of the Leeuwin Current probably led to an enhanced carbon flux at the seafloor that favored prolific bryozoan growth and mound formation at Site 1132. At Site 1129, higher temperatures and downwelling appear to have inhibited the full development of bryozoan mounds during stages 2-4. During that time, favorable hydrographic conditions for the growth of bryozoan mounds shifted downslope from Site 1129 to Site 1131. Superimposed on these glacial-interglacial fluctuations is a distinct long-term paleoceanographic change. Prior to stage 8, benthic foraminiferal assemblages indicate low carbon flux to the seafloor, and bryozoan mounds, although present closer inshore, did not accumulate significantly at Sites 1129 and 1132, even during glacials. Our results show that the interplay of sea level change (eustatic and local, linked to platform progradation), glacial-interglacial carbon flux fluctuations (linked to local hydrographic variations), and possibly long-term climatic change strongly influenced the evolution of the Great Australian Bight carbonate margin during the late Pleistocene.

The MIS 5 palaeoenvironmental record in the SE Mediterranean coast of the Iberian Peninsula (Río Antas, Almería, Spain)

Se realiza un estudio detallado del episodio cálido MIS 5 en la zona sureste de la Península Ibérica. Se realiza la reconstrucción paleoambiental a partir del estudio polínico y biomarcadores de un sondeo perforado en la costa de Almería. La cronología se estableció a partir del método de racemizaciónd e aminoácidos.Landwards of a MIS5 bar, a borehole core (SRA) was analyzed to establish the relationship between the lagoonal record and the raised beach deposits in the surroundings of the Antas river mouth and to reconstruct the Pleistocene palaeoenvironmental evolution 5 of the southern Mediterranean coast of the Iberian Peninsula. 63 samples were recovered for amino acid racemization dating, 86 samples for sedimentological and paleontological determination, 37 samples for pollen identification and 54 for biomarker analysis. AAR revealed that the borehole record contains MIS11, MIS6 and MIS5 deposits, the latter extensively represented. During the end of MIS6 and MIS5, a sand 10 barrier developed and created a shallow lagoon with alternating terrestrial inputs this process being common in other Mediterranean realms. Litho- and biofacies allowed the identification of distinct paleoenvironments through time, with the presence of a lagoonal environment alternating with alluvial fan progradation. Biomarkers indicated constant input from terrestrial plants, together with variable development of aquatic 15 macrophytes. The palynological content allowed the reconstruction of the paleoclimatological conditions during MIS6 and 5, with evidence of seven scenarios characterized by alternating arid and relatively humid conditions

Cyclically-arranged, storm-controlled, prograding lithosomes in Messinian terrigenous shelves (Bajo Segura Basin, western Mediterranean)

This work focuses on a Messinian shallow-marine terrigenous unit, termed the La Virgen Formation, which forms part of the sedimentary infill of the Bajo Segura Basin (Betic margin of the western Mediterranean). This formation was deposited during a high sea level phase prior to the onset of the Messinian Salinity Crisis. Stratigraphically, it comprises a prograding stack of sandstone lithosomes alternating with marly intervals (1st-order cyclicity). These lithosomes are characterized by a homoclinal geometry that tapers distally, and interfinger with pelagic sediments rich in planktonic and benthic microfauna (Torremendo Formation). An analysis of sedimentary facies of each lithosome reveals a repetitive succession of sandy storm beds (tempestites), occasionally amalgamated, which are separated by thin marly layers (2nd-order cyclicity). Each storm bed contains internal erosional surfaces (3rd-order cyclicity) that delimit sets of laminae. Two categories of storm beds have been differentiated. The first one includes layers formed below storm wave base (SWB), characterized by traction structures associated to unidirectional flows (scoured base, planar lamination, and parting lineation). The second category consists of layers deposited above the SWB which display typical high regime oscillatory flow structures (swaley and hummocky cross lamination). In both cases, the ichnological record is characterized by an oligotypic association of Ophiomorpha nodosa, which can be interpreted as the result of allochthonous tracemakers (crustaceans) transported during storm events together with the sediment. The benthic microfauna in the marly intervals that separate the sandstone lithosomes (1st-order cyclicity) indicates that the storm ebb surges were deposited at depths ranging from those of inner shelf settings (with Elphidium spp. and Cibicides lobatulus) to those of outer shelf (with Valvulineria complanata and Uvigerina cylindrica). At the distal end of the sandstone lithosomes, the planktonic microfauna is characterized by a high content of taxa indicative of warm-oligotrophic waters (Globigerinoides obliquus and Globigerinoides bulloideus). In contrast, in the marly intervals, the microfauna is dominated by species typical of cold-eutrophic waters (Globigerina and Neogloboquadrina). This alternation of planktic foraminiferal assemblages is interpreted as being the expression of climatic cycles, in which every episode of progradation of tempestite-dominated lithosomes corresponds to maximum insolation and warm waters, whereas episodes of marly deposition correspond to minimal insolation and cold waters. The 1st-order cyclicity recorded in the La Virgen Formation, in a context of terrigenous storm-dominated shelf, corresponds to sapropel/homogeneous marl cycles formed in a pelagic basin (Torremendo Fm). These cycles in pelagic sediments are commonplace throughout the Mediterranean during the Messinian and reflect precession orbital changes: repeated periods of maximum insolation – minimum precession (sapropels) and minimal insolation – maximum precession (homogeneous marls). The fact that the example of terrigenous unit studied herein is coetaneous with the well-developed reef complexes in the Mediterranean basins points out the importance of sediment supply in the formation of large-scale sandy lithosomes. This is a crucial aspect to understanding reservoir genesis as well as lateral stratigraphic relationships with potential seal and/or source rocks.

Detrital zircon geochronology data, petrographic point count data and paleocurrent indicator data of Triassic turbidites in the Nanpanjiang Basin, South China

Triassic turbidites of the Nanpanjiang basin of south China represent the most expansive and voluminous siliciclastic turbidite accumulation in south China. The Nanpanjiang basin occurs at a critical junction between the southern margin of the south China plate and the Indochina, Siamo and Sibumasu plates to the south and southwest. The Triassic Yangtze carbonate shelf and isolated carbonated platforms in the basin have been extensively studied, but silicilastic turbidites in the basin have received relatively little attention. Deciphering the facies, paleocurrent indicators and provenance of the Triassic turbidites is important for several reasons: it promises to help resolve the timing of plate collisions along suture zones bordering the basin to the south and southwest, it will enable evaluation of which suture zones and Precambrian massifs were source areas, and it will allow an evaluation of the impact of the siliciclastic flux on carbonate platform evolution within the basin. Turbidites in the basin include the Early Triassic Shipao Formation and the Middle-Late Triassic Baifeng, Xinyuan, Lanmu Bianyang and Laishike formations. Each ranges upward of 700 m and the thickest is nearly 3 km. The turbidites contain very-fine sand in the northern part of the basin whereas the central and southern parts of the basin also commonly contain fine and rarely medium sand size. Coarser sand sizes occur where paleocurrents are from the south, and in this area some turbidites exhibit complete bouma sequences with graded A divisions. Successions contain numerous alternations between mud-rich and sand-rich intervals with thickness trends corresponding to proximal/ distal fan components. Spectacularly preserved sedimentary structures enable robust evaluation of turbidite systems and paleocurrent analyses. Analysis of paleocurrent measurements indicates two major directions of sediment fill. The northern part of the basin was sourced primarily by the Jiangnan massif in the northeast, and the central and southern parts of the basin were sourced primarily from suture zones and the Yunkai massif to the south and southeast respectively. Sandstones of the Lower Triassic Shipao Fm. have volcaniclastic composition including embayed quartz and glass shards. Middle Triassic sandstones are moderately mature, matrix-rich, lithic wackes. The average QFL ratio from all point count samples is 54.1/18.1/27.8% and the QmFLt ratio is 37.8/ 18.1/ 44.1%. Lithic fragments are dominantly claystone and siltstone clasts and metasedimentary clasts such as quartz mica tectonite. Volcanic lithics are rare. Most samples fall in the recycled orogen field of QmFLt plots, indicating a relatively quartz and lithic rich composition consistent with derivation from Precambrian massifs such as the Jiangnan, and Yunkai. A few samples from the southwest part of the basin fall into the dissected arc field, indicating a somewhat more lithic and feldspar-rich composition consistent with derivation from a suture zone Analysis of detrial zircon populations from 17 samples collected across the basin indicate: (1) Several samples contain zircons with concordant ages greater than 3000 Ma, (2) there are widespread peaks across the basin at 1800 Ma and 2500, (3) a widespread 900 Ma population, (3) a widespread population of zircons at 440 Ma, and (5) a larger population of younger zircons about 250 Ma in the southwestern part which is replaced to the north and northwest by a somewhat older population around 260-290 Ma. The 900 Ma provenance fits derivation from the Jiangnan Massif, the 2500, 1800, and 440 Ma provenance fits the Yunkai massif, and the 250 Ma is consistent with convergence and arc development in suture zones bordering the basin on the south or southwest. Early siliciclastic turbidite flux, proximal to source areas impacted carbonate platform evolution by infilling the basin, reducing accommodation space, stabilizing carbonate platform margins and promoting margin progradation. Late arrival, in areas far from source areas caused margin aggradation over a starved basin, development of high relief aggradational escarpments and unstable scalloped margins.

Beach face and berm morphodynamics fronting a coastal lagoon

This study documents two different modes of berm development: (I) vertical growth at spring tides or following significant beach cut due to substantial swash overtopping, and (2) horizontal progradation at neap tides through the formation of a proto-berm located lower and further seaward of the principal berm. Concurrent high-frequency measurements of bed elevation and the associated wave runup distribution reveal the details of each of these berm growth modes. In mode I sediment is eroded from the inner surf and lower swash zone where swash interactions are prevalent. The net transport of this sediment is landward only, resulting in accretion onto the upper beach face and over the berm crest. The final outcome is a steepening of the beach face gradient, a change in the profile shape towards concave and rapid vertical and horizontal growth of the berm. In mode 2 sediment is eroded from the lower two-thirds of the active swash zone during the rising tide and is transported both landward and seaward. On the falling tide sediment is eroded from the inner surf and transported landward to backfill the zone eroded on the rising tide. The net result is relatively slow steepening of the beach face, a change of the profile shape towards convex, and horizontal progradation through the formation of a neap berm. The primary factor determining which mode of berm growth occurs is the presence or absence of swash overtopping at the time of sediment accumulation on the beach face. This depends on the current phase of the spring-neap tide cycle, the wave runup height (and indirectly offshore wave conditions) and the height of the pre-existing berm. A conceptual model for berm morphodynamics is presented, based on sediment transport shape functions measured during the two modes of berm growth. (c) 2006 Elsevier B.V. All rights reserved.

Paleoenvironments and geochemical signals from the late Barremian to the middle Aptian in a Tethyan marginal basin, northeast Spain: Implications for carbon sequestration in restricted basins

The hallmark of oceanic anoxic event 1a (OAE1a) (early Aptian ~125 Ma) corresponds to worldwide deposition of black shales with total organic carbon (TOC) content > 2% and a δ13C positive excursion up to ~5‰. OAE1a has been related to large igneous province volcanism and dissociation of methane hydrates during the Lower Cretaceous. However, the occurrence of atypical, coeval and diachronous organic-rich deposits associated with OAE1a, which are also characterized by positive spikes of the δ 13C in epicontinental to restricted marine environments of the Tethys Ocean, indicates localized responses decoupled from complex global forcing factors. ^ The present research is a high-resolution, multiproxy approach to assess the paleoenvironmental conditions that led to enhanced carbon sequestration from the late Barremian to the middle Aptian in a restricted, Tethyan marginal basin prior to and during OAE1a. I studied the lower 240 m of the El Pui section, Organyà Basin, Spanish Pyrenees. The basin developed as the result of extensional tectonism linked to the opening of the Atlantic Ocean. At the field scale the section consists of a sequence of alternating beds of cm – m-scale, medium-gray to grayish-black limestones and marlstones with TOC up to ~4%. ^ The results indicate that the lowest 85 m of the section, from latest Barremian -earliest Aptian, characterize a deepening phase of the basin concomitant with sustained riverine flux and intensified primary productivity. These changes induced a shift in the sedimentation pattern and decreased the oxygen levels in the water column through organic matter respiration and limited ventilation of the basin. ^ The upper 155 m comprising the earliest – late-early Aptian document the occurrence of OAE1a and its associated geochemical signatures (TOC up to 3% and a positive shift in δ13C of ~5‰). However, a low enrichment of redox-sensitive trace elements indicates that the basin did not achieve anoxic conditions. The results also suggest that a shallower-phase of the basin, coeval with platform progradation, may have increased ventilation of the basin at the same time that heightened sedimentation rates and additional input of organic matter from terrestrial sources increased the burial and preservation rate of TOC in the sediment.^

Vertical trends within the prograding Salt Wash distributive fluvial system, SW USA

Peer reviewed

Die mittelpleistozäne Flußentwicklung im nordöstlichen Harzvorland: Petrographie, Terrassenstratigraphie

The present study deals with the evolution of the middle Pleistocene river system in the north-eastern foreland of the Harz Mtns. Sediments of the middle fluvial terrace level (early Saalian time) are the main objectives. By using these sediments supplementary with some results of upper fluvial terrace level (early Elesterian time or older) the fluvial palaeogeography within the area has been reconstructed. The sediments were investigated with respect to their gravel spectra, heavy mineral record, sedimentary structures and altitude above the recent river beds. Due to the resulting specifics the sediments have been attributed to particular rivers in the area. Furthermore it is possible to distinguish between fluvial sediments and Elsterian as well as Saalian fluvioglacial deposits. Together with discernible middle or upper terrace characteristics this led to a spatio-temporal reconstruction of the palaeo river system of the Harz Mtns. It revealed that not only during upper terrace sedimentation but even while middle terraces were deposited the rivers partly diversed. These river diversions were mainly caused by hydrodynamic changes reflecting interaction of the fluvial system with Elsterian and Saalian ice shield formation in the north. The Rivers Ecker, Ilse, Rammelsbach, Holtemme, Goldbach, Bode, Selke and Eine were affected by this development as follows: Upper terrace level formation: • The Ecker River formerly ran between its recent river bed and that of the Use River in direction to the Großer Fallstein Mtn. • The Use River flowed to the NE towards the Huy Mtn. • The Goldbach River and the Holtemme River mutually ran to the NW south of the Huy Mtn. After uniting with the Use River and Ecker River it ran south of the Großer Fallstein Mtn. Middle terrace level formation: • The Ecker River flowed far more NE. • Near to the Harz Mtns. the Use River flowed more in the E. The tributary junction of the Rammelsbach River was located far more downstream. Thereafter the Use River ran to the N between Huy Mtn. and Großer Fallstein Mtn. to end up flowing in the area of the Großes Bruch. • The Holtemme River kept its course. Its recent tributary the Goldbach River flowed to the NE and joined the Bode River after leaving the Harz Mtn. Range. • The Eine River ran to the NW when passing todays city of Aschersleben. After flowing together with the Selke River in the area of the Seeländerei it became a tributary to the Bode River. • The Bode River within the recent tributary junction of the Holtemme ran far more in the W. In the area of the Espenbruch it flowed eastwards to the Saale River. The following general implications resulted out of the study: • The so called “mixed sediments” sensu Rosenberger & Altermann (1975) have now been interpreted as proximal fluvioglacial deposits. • High altitudes of middle terrace fluvial deposits in the courses of the Ecker River and Use River were formerly assigned to post middle Pleistocene uplift of the Großer Fallstein Mtn. (Feldmann, 2002). The present study suggests that the unusual high altitudes should rather be attributed to post middle terrace level erosion of the shortened Ilse- Rammelsbach river system or fluvioglacial processes below the glacier. • Within the north-eastern foreland of the Harz Mtns. middle terrace level deposits have previously been subdivided by cryoturbation horizons or short-term progradation of Saalian glaciation. This is not supported by own results for the examined area.

Sedimentary archives of climate and sea-level changes during the Holocene in the Rhone prodelta (NW Mediterranean Sea)

A 7.38 m-long sediment core was collected from the eastern part of the Rhone prodelta (NW Mediterranean) at 67 m water depth. A multi-proxy study (sedimentary facies, benthic foraminifera and ostracods, clay mineralogy, and major elements from XRF) provides a multi-decadal to century-scale record of climate and sea-level changes during the Holocene. The early Holocene is marked by alternative silt and clay layers interpreted as distal tempestites deposited in a context of rising sea level. This interval contains shallow infra-littoral benthic meiofauna (e.g. Pontocythere elongata, Elphidium spp., Quinqueloculina lata) and formed between ca. 20 and 50 m water depth. The middle Holocene (ca. 8.3 to 4.5 ka cal. BP), is characterized, at the core site, by a period of sediment starvation (accumulation rate of ca. 0.01 cm yr−1) resulting from the maximum landward shift of the shoreline and the Rhone outlet(s). From a sequence stratigraphic point of view, this condensed interval, about 35 cm-thick, is a Maximum Flooding Surface that can be identified on seismic profiles as the transition between delta retrogradation and delta progradation. It is marked by very distinct changes in all proxy records. Following the stabilization of the global sea level, the late Holocene is marked by the establishment of prodeltaic conditions at the core site, as shown by the lithofacies and by the presence of benthic meiofauna typical of the modern Rhone prodelta (e.g. Valvulineria bradyana, Cassidulina carinata, Bulimina marginata). Several periods of increased fluvial discharge are also emphasized by the presence of species commonly found in brackish and shallow water environments (e.g. Leptocythere). Some of these periods correspond to the multi-decadal to centennial late Holocene humid periods recognized in Europe (i.e. the 2.8 ka event and the Little Ice Age). Two other periods of increased runoffs at ca. 1.3 and 1.1 ka cal. BP are recognized, and are likely to reflect periods of regional climate deterioration that are observed in the Rhone watershed.