The Quaternary vertebrate fauna of the limestone cave Gruta do Ioio, northeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização hidrogeoquímica, isotópica e diagenética do sistema aquífero Bauru no Estado de São Paulo

Pós-graduação em Geociências e Meio Ambiente - IGCE

Caracterização hidrogeoquímica, isotópica e diagenética do sistema aquífero Bauru no Estado de São Paulo

Pós-graduação em Geociências e Meio Ambiente - IGCE

Facies associations and controls on the evolution from a coastal bay to a lagoon system, Santa Catarina Coast, Brazil

The diverse Holocene morphological features along the south coast of the state of Santa Catarina include lagoons and residual lakes, a barrier, a delta (constructed by the Tubarao River), and pre-existing incised valleys that have flooded and filled. This scenario contains the sedimentary record of the transition from a bay to a lagoon system, which occurred during the rise and subsequent semi-stabilisation of the relative sea-level during the Holocene. The geomorphological evolution of this area was investigated using a combination of morphology, stratigraphic analysis of rotary push cores, vibracores and trenches with radiocarbon dating, taxonomic determination and taphonomic characterisation of Holocene fossil molluscs. Palaeogeographic maps were constructed to illustrate how the bay evolved over the last 8000 years. The relative sea-level rise and local sedimentary processes were the prime forcing factors determining the depositional history and palaeogeographic changes. The Holocene sedimentary succession began between 8000 and 5700 cal BP with the deposits of transgressive sandsheets. These deposits correspond to the initial marine flooding surface that was formed while the relative sea-level rose at a higher rate than the input of sediments, prior to the formation of the coastal barrier. The change from a bay to a lagoon system occurred around 5700 and 2500 cal BP during the mid-Holocene highstand with the formation of the barrier and with the achievement of a balance between sea-level rise and sedimentary supply. Until 2500 cal BP, the presence of this barrier, the following gentle decline in sea level and the initial emergence of back-barrier features restricted the hydro-dynamic circulation inside the bay and favoured an increase in the Tubarao River delta progradation rate. The final stage, during the last 2500 years, was marked by the increasing back-barrier width, with the establishment of salt marshes, the arrival of the delta in the back-barrier, and the advance of aeolian dunes along the outer lagoon margins. This study shed light on the mechanisms of coastal bay evolution in a setting existed prior to the beginning of barrier lagoon sedimentation. (C) 2012 Elsevier B.V. All rights reserved.

Evidenze micropaleontologiche e sedimentologiche di cicli deposizionali e climatici circa millenari nei Depositi Tardoquaternari della Piana dell'Arno e del Delta del Po

A multidisciplinary study was carried out on the Late Quaternary-Holocene subsurface deposits of two Mediterranean coastal areas: Arno coastal plain (Northern Tyrrhenian Sea) and Modern Po Delta (Northern Adriatic Sea). Detailed facies analyses, including sedimentological and micropalaeontological (benthic foraminifers and ostracods) investigations, were performed on nine continuously-cored boreholes of variable depth (ca. from 30 meters to100 meters). Six cores were located in the Arno coastal plain and three cores in the Modern Po Delta. To provide an accurate chronological framework, twenty-four organic-rich samples were collected along the fossil successions for radiocarbon dating (AMS 14C). In order to reconstruct the depositional and palaeoenvironmental evolution of the study areas, core data were combined with selected well logs, provided by local companies, along several stratigraphic sections. These sections revealed the presence of a transgressive-regressive (T-R) sequence, composing of continental, coastal and shallow-marine deposits dated to the Late Pleistocene-Holocene period, beneath the Arno coastal plain and the Modern Po Delta. Above the alluvial deposits attributed to the last glacial period, the post-glacial transgressive succession (TST) consists of back-barrier, transgressive barrier and inner shelf deposits. Peak of transgression (MFS) took place around the Late-Middle Holocene transition and was identified by subtle micropalaeontological indicators within undifferentiated fine-grained deposits. Upward a thick prograding succession (HST) records the turnaround to regressive conditions that led to a rapid delta progradation in both study areas. Particularly, the outbuilding of modern-age Po Delta coincides with mud-belt formation during the late HST (ca. 600 cal yr BP), as evidenced by a fossil microfauna similar to the foraminiferal assemblage observed in the present Northern Adriatic mud-belt. A complex interaction between allocyclic and autocyclic factors controlled facies evolution during the highstand period. The presence of local parameters and the absence of a predominant factor prevent from discerning or quantifying consequences of the complex relationships between climate and deltaic evolution. On the contrary transgressive sedimentation seems to be mainly controlled by two allocyclic key factors, sea-level rise and climate variability, that minimized the effects of local parameters on coastal palaeoenvironments. TST depositional architecture recorded in both study areas reflects a well-known millennial-scale variability of sea-level rising trend and climate during the Late glacial-Holocene period. Repeated phases of backswamp development and infilling by crevasse processes (parasequences) were recorded in the subsurface of Modern Po Delta during the early stages of transgression (ca. 11,000-9,500 cal yr BP). In the Arno coastal plain the presence of a deep-incised valley system, probably formed at OSI 3/2 transition, led to the development of a thick (ca. 35-40 m) transgressive succession composed of coastal plain, bay-head delta and estuarine deposits dated to the Last glacial-Early Holocene period. Within the transgressive valley fill sequence, high-resolution facies analyses allowed the identification and lateral tracing of three parasequences of millennial duration. The parasequences, ca. 8-12 meters thick, are bounded by flooding surfaces and show a typical internal shallowing-upward trend evidenced by subtle micropalaeontological investigations. The vertical stacking pattern of parasequences shows a close affinity with the step-like sea-level rising trend occurred between 14,000-8,000 cal years BP. Episodes of rapid sea-level rise and subsequent stillstand phases were paralleled by changes in climatic conditions, as suggested by pollen analyses performed on a core drilled in the proximal section of the Arno palaeovalley (pollen analyses performed by Dr. Marianna Ricci Lucchi). Rapid shifts to warmer climate conditions accompanied episodes of rapid sea-level rise, in contrast stillstand phases occurred during temporary colder climate conditions. For the first time the palaeoclimatic signature of high frequency depositional cycles is clearly documented. Moreover, two of the three "regressive" pulsations, recorded at the top of parasequences by episodes of partial estuary infilling in the proximal and central portions of Arno palaeovalley, may be correlated with the most important cold events of the post-glacial period: Younger Dryas and 8,200 cal yr BP event. The stratigraphic and palaeoclimatic data of Arno coastal plain and Po Delta were compared with those reported for the most important deltaic and coastal systems in the worldwide literature. The depositional architecture of transgressive successions reflects the strong influence of millennial-scale eustatic and climatic variability on worldwide coastal sedimentation during the Late glacial-Holocene period (ca. 14,000-7,000 cal yr BP). The most complete and accurate record of high-frequency eustatic and climatic events are usually found within the transgressive succession of very high accommodation settings, such as incised-valley systems where exceptionally thick packages of Late glacial-Early Holocene deposits are preserved.

Integrating new and traditional approaches for the estimate of slip-rates of active faults: examples from the Mw 6.3, 2009 L’Aquila earthquake area, Central Italy

This thesis is based on the integration of traditional and innovative approaches aimed at improving the normal faults seimogenic identification and characterization, focusing mainly on slip-rate estimate as a measure of the fault activity. The L’Aquila Mw 6.3 April 6, 2009 earthquake causative fault, namely the Paganica - San Demetrio fault system (PSDFS), was used as a test site. We developed a multidisciplinary and scale‐based strategy consisting of paleoseismological investigations, detailed geomorphological and geological field studies, as well as shallow geophysical imaging and an innovative application of physical properties measurements. We produced a detailed geomorphological and geological map of the PSDFS, defining its tectonic style, arrangement, kinematics, extent, geometry and internal complexities. The PSDFS is a 19 km-long tectonic structure, characterized by a complex structural setting and arranged in two main sectors: the Paganica sector to the NW, characterized by a narrow deformation zone, and the San Demetrio sector to SE, where the strain is accommodated by several tectonic structures, exhuming and dissecting a wide Quaternary basin, suggesting the occurrence of strain migration through time. The integration of all the fault displacement data and age constraints (radiocarbon dating, optically stimulated luminescence (OSL) and tephrochronology) helped in calculating an average Quaternary slip-rate representative for the PSDFS of 0.27 - 0.48 mm/yr. On the basis of its length (ca. 20 km) and slip per event (up to 0.8 m) we also estimated a max expected Magnitude of 6.3-6.8 for this fault. All these topics have a significant implication in terms of surface faulting hazard in the area and may contribute also to the understanding of the PSDFS seismic behavior and of the local seismic hazard.

Ancient Greek harbours used as geo-archives for palaeotsunami research : case studies from Krane (Cefalonia), Lechaion (Gulf of Corinth) and Kyllini (Peloponnese)

Since historical times, coastal areas throughout the eastern Mediterranean are exposed to tsunami hazard. For many decades the knowledge about palaeotsunamis was solely based on historical accounts. However, results from timeline analyses reveal different characteristics affecting the quality of the dataset (i.e. distribution of data, temporal thinning backward of events, local periodization phenomena) that emphasize the fragmentary character of the historical data. As an increasing number of geo-scientific studies give convincing examples of well dated tsunami signatures not reported in catalogues, the non-existing record is a major problem to palaeotsunami research. While the compilation of historical data allows a first approach in the identification of areas vulnerable to tsunamis, it must not be regarded as reliable for hazard assessment. Considering the increasing economic significance of coastal regions (e.g. for mass tourism) and the constantly growing coastal population, our knowledge on the local, regional and supraregional tsunami hazard along Mediterranean coasts has to be improved. For setting up a reliable tsunami risk assessment and developing risk mitigation strategies, it is of major importance (i) to identify areas under risk and (ii) to estimate the intensity and frequency of potential events. This approach is most promising when based on the analysis of palaeotsunami research seeking to detect areas of high palaeotsunami hazard, to calculate recurrence intervals and to document palaeotsunami destructiveness in terms of wave run-up, inundation and long-term coastal change. Within the past few years, geo-scientific studies on palaeotsunami events provided convincing evidence that throughout the Mediterranean ancient harbours were subject to strong tsunami-related disturbance or destruction. Constructed to protect ships from storm and wave activity, harbours provide especially sheltered and quiescent environments and thus turned out to be valuable geo-archives for tsunamigenic high-energy impacts on coastal areas. Directly exposed to the Hellenic Trench and extensive local fault systems, coastal areas in the Ionian Sea and the Gulf of Corinth hold a considerably high risk for tsunami events, respectively.Geo-scientific and geoarcheaological studies carried out in the environs of the ancient harbours of Krane (Cefalonia Island), Lechaion (Corinth, Gulf of Corinth) and Kyllini (western Peloponnese) comprised on-shore and near-shore vibracoring and subsequent sedimentological, geochemical and microfossil analyses of the recovered sediments. Geophysical methods like electrical resistivity tomography and ground penetrating radar were applied in order to detect subsurface structures and to verify stratigraphical patterns derived from vibracores over long distances. The overall geochronological framework of each study area is based on radiocarbon dating of biogenic material and age determination of diagnostic ceramic fragments. Results presented within this study provide distinct evidence of multiple palaeotsunami landfalls for the investigated areas. Tsunami signatures encountered in the environs of Krane, Lechaion and Kyllini include (i) coarse-grained allochthonous marine sediments intersecting silt-dominated quiescent harbour deposits and/or shallow marine environments, (ii) disturbed microfaunal assemblages and/or (iii) distinct geochemical fingerprints as well as (iv) geo-archaeological destruction layers and (v) extensive units of beachrock-type calcarenitic tsunamites. For Krane, geochronological data yielded termini ad or post quem (maximum ages) for tsunami event generations dated to 4150 ± 60 cal BC, ~ 3200 ± 110 cal BC, ~ 650 ± 110 cal BC, and ~ 930 ± 40 cal AD, respectively. Results for Lechaion suggest that the harbour was hit by strong tsunami impacts in the 8th-6th century BC, the 1st-2nd century AD and in the 6th century AD. At Kyllini, the harbour site was affected by tsunami impact in between the late 7th and early 4th cent. BC and between the 4th and 6th cent. AD. In case of Lechaion and Kyllini, the final destruction of the harbour facilities also seems to be related to the tsunami impact. Comparing the tsunami signals obtained for each study areas with geo-scientific data from palaeotsunami events from other sites indicates that the investigated harbour sites represent excellent geo-archives for supra-regional mega-tsunamis.

Palaeotsunami imprints in the near-coast sedimentary records of the Gulfs of Lakonia and Argolis (Peloponnese, Greece)

From historical accounts it is well-known that the coasts of the Gulfs of Lakonia and Argolis (southern and eastern Peloponnese, Greece) have been repeatedly affected by tsunamis during historical times. It is assumed that these palaeotsunamis left sedimentological and geomorphological traces in the geological record which are still detectable these days. As both gulfs are located within one of the seismically most active regions in whole western Eurasia in particular the nearby Hellenic Trench is regarded as the main trigger for tsunami generation. Against this background, selected near-coast sedimentary archives were studied by means of sedimentological, geomorphological, geophysical, geochemical and microfaunal investigations in order to detect signatures of Holocene palaeotsunamigenic activity. The investigations revealed allochthonous sediment layers featuring distinctive sedimentary characteristics of marine high-energy event deposits in most of the investigated study areas. In order to differentiate between the geomorphodynamic driving mechanisms for the deposition of the associated marine high-energy event layers, a multi-method approach was used. The detected high-energy marine deposits are suggested to be of tsunamigenic origin. Radiocarbon dating results allowed establishing local event geo-chronostratigraphies and correlations on a local and regional scale as well as correlations with already described palaeotsunami findings on a supra-regional scale. The geochronological dataset attests repeated tsunamigenic activity at least since the 5th millennium BC up to the 17th century AD. For the studied areas in southeastern Lakonia up to four palaeotsunami event generations were identified, for central Lakonia three and for the investigated areas around the Argolis Gulf also up to four. Comparing the findings with literature data, chronological correlations were found with palaeotsunami deposits detected in near-coast geological archives of Akarnania, of the southwestern, the western and northwestern Peloponnese, with event deposits found on Crete and on the Ionian Islands of Cefalonia and Lefkada as well as with findings from southeastern Sicily (Italy) and Cesarea (Israel). By the identification of multiple palaeotsunami event layers, disturbing autochthonous near-coast sedimentary records of the Gulfs of Lakonia and Argolis during the last seven millennia, a significant tsunami frequency is attested for these regions.

Unique paleopathology in a pre-Columbian mummy remnant from Southern Peru--severe cervical rotation trauma with subluxation of the axis as cause of death

We describe the multidisciplinary findings in a pre-Columbian mummy head from Southern Peru (Cahuachi, Nazca civilisation, radiocarbon dating between 120 and 750 AD) of a mature male individual (40-60 years) with the first two vertebrae attached in pathological position. Accordingly, the atlanto-axial transition (C1/C2) was significantly rotated and dislocated at 38° angle associated with a bulging brownish mass that considerably reduced the spinal canal by circa 60%. Using surface microscopy, endoscopy, high-resolution multi-slice computer tomography, paleohistology and immunohistochemistry, we identified an extensive epidural hematoma of the upper cervical spinal canal-extending into the skull cavity-obviously due to a rupture of the left vertebral artery at its transition between atlas and skull base. There were no signs of fractures of the skull or vertebrae. Histological and immunohistochemical examinations clearly identified dura, brain residues and densely packed corpuscular elements that proved to represent fresh epidural hematoma. Subsequent biochemical analysis provided no evidence for pre-mortal cocaine consumption. Stable isotope analysis, however, revealed significant and repeated changes in the nutrition during his last 9 months, suggesting high mobility. Finally, the significant narrowing of the rotational atlanto-axial dislocation and the epidural hematoma probably caused compression of the spinal cord and the medulla oblongata with subsequent respiratory arrest. In conclusion, we suggest that the man died within a short period of time (probably few minutes) in an upright position with the head rotated rapidly to the right side. In paleopathologic literature, trauma to the upper cervical spine has as yet only very rarely been described, and dislocation of the vertebral bodies has not been presented.

Catastrophic Flooding In North-Central Pennsylvania: Geomorphic Findings From The September 2011 Event And Their Significance To

Tropical Storm Lee produced 25-36 cm of rainfall in north-central Pennsylvania on September 4th through 8th of 2011. Loyalsock Creek, Muncy Creek, and Fishing Creek experienced catastrophic flooding resulting in new channel formation, bank erosion, scour of chutes, deposition/reworking of point bars and chute bars, and reactivation of the floodplain. This study was created to investigate aspects of both geomorphology and sedimentology by studying the well-exposed gravel deposits left by the flood, before these features are removed by humans or covered by vegetation. By recording the composition of gravel bars in the study area and creating lithofacies models, it is possible to understand the 2011 flooding. Surficial clasts on gravel bars are imbricated, but the lack of imbrication and high matrix content of sediments at depth suggests that surface imbrication of the largest clasts took place during hyperconcentrated flow (40-70% sediment concentration). The imbricated clasts on the surface are the largest observed within the bars. The lithofacies recorded are atypical for mixed-load stream lithofacies and more similar to glacial outburst flood lithofacies. This paper suggests that the accepted lithofacies model for mixed-load streams with gravel bedload may not always be useful for interpreting depositional systems. A flume study, which attempted to duplicate the stratigraphy recorded in the field, was run in order to better understand hyperconcentrated flows in the study area. Results from the study in the Bucknell Geology Flume Laboratory indicate that surficial imbrication is possible in hyperconcentrated conditions. After flooding the flume to entrain large amounts of sand and gravel, deposition of surficially imbricated gravel with massive or upward coarsening sedimentology occurred. Imbrication was not observed at depth. These experimental flume deposits support our interpretation of the lithofacies discovered in the field. The sizes of surficial gravel bar clasts show clear differences between chute and point bars. On point bars, gravels fine with increasing distance from the channel. Fining also occurs at the downstream end of point bars. In chute deposits, dramatic fining occurs down the axis of the chute, and lateral grain sizes are nearly uniform. Measuring the largest grain size of sandstone clasts at 8-11 kilometer intervals on each river reveals anomalies in the downstream fining trends. Gravel inputs from bedrock outcrops, tributaries, and erosion of Pleistocene outwash terraces may explain observed variations in grain size along streams either incised into the Appalachian Plateau or located near the Wisconsinan glacial boundary. Atomic Mass Spectrometry (AMS) radiocarbon dating of sediment from recently scoured features on Muncy Creek and Loyalsock Creek returned respective ages of 500 BP and 2490 BP. These dates suggest that the recurrence interval of the 2011 flooding may be several hundred to several thousand years. This geomorphic interval of recurrence is much longer then the 120 year interval calculated by the USGS using historical stream gauge records.

Palaeohydrology, fires and vegetation succession in the southern Baltic during the last 7500 years reconstructed from a raised bog based on multi-proxy data

We present the first 7500 yr long multi-proxy record from a raised bog located at the southern Baltic coast, Poland. Testate amoebae, plant macrofossils, pollen and microscopic charcoal were used to reconstruct environmental changes in Pomerania (northern Poland, Kaszuby Lakeland) from a 7-m thick peat archive of Stążki bog dated 5500 BC–AD 1250. We obtained a record of proxies representing different spatial scales: regional vegetation changed simultaneously with local vegetation, and testate amoebae showed a pattern of change similar to that of pollen and plant macrofossils. On the basis of the combined proxies, we distinguished three hydroclimatic stages: moist conditions 5500–3450 BC, drier conditions with regionally increased fires up to 600 BC, and again moist conditions from 600 BC onward. During the drier interval, a first climatic shift to wetter conditions at 1700 BC is indicated by regional pollen as the replacement of Corylus by Carpinus, and locally by, e.g., the increase of Hyalosphenia elegans and mire plants such as Sphagnum sec. Cuspidata. Furthermore, we observed a correlation since 600 BC among the re-expansion of Carpinus (after a sudden decline ca. 950 BC), increased peat accumulation, increase of Hyalosphenia species, and fewer fires, suggesting lower evapotranspiration and a stable high water table in the bog. Fagus started to expand after AD 810 gradually replacing Carpinus, which was possibly due to a gradually more oceanic climate, though we cannot exclude human impact on the forests. Peat accumulation, determined by radiocarbon dating, varied with bog surface wetness. The hydroclimatic phases found in Stążki peatland are similar to moisture changes recorded in other sites from Poland and Europe. This is the first detailed record of hydroclimatic change during the Holocene in the southern Baltic region, so it forms a reference site for further studies on other southern Baltic bogs that are in progress.

Early and Middle Holocene Hunter-Gatherer Occupations in Western Amazonia: The Hidden Shell Middens

We report on previously unknown early archaeological sites in the Bolivian lowlands, demonstrating for the first time early and middle Holocene human presence in western Amazonia. Multidisciplinary research in forest islands situated in seasonally-inundated savannahs has revealed stratified shell middens produced by human foragers as early as 10,000 years ago, making them the oldest archaeological sites in the region. The absence of stone resources and partial burial by recent alluvial sediments has meant that these kinds of deposits have, until now, remained unidentified. We conducted core sampling, archaeological excavations and an interdisciplinary study of the stratigraphy and recovered materials from three shell midden mounds. Based on multiple lines of evidence, including radiocarbon dating, sedimentary proxies (elements, steroids and black carbon), micromorphology and faunal analysis, we demonstrate the anthropogenic origin and antiquity of these sites. In a tropical and geomorphologically active landscape often considered challenging both for early human occupation and for the preservation of hunter-gatherer sites, the newly discovered shell middens provide evidence for early to middle Holocene occupation and illustrate the potential for identifying and interpreting early open-air archaeological sites in western Amazonia. The existence of early hunter-gatherer sites in the Bolivian lowlands sheds new light on the region’s past and offers a new context within which the late Holocene “Earthmovers” of the Llanos de Moxos could have emerged.

Geomorphological and sedimentary evidence for late Pleistocene to Holocene hydrological change along the Río Mamoré, Bolivian Amazon

Aerial photography and satellite imagery reveal manifold geomorphological evidence of a dynamic evolution of past and present rivers in the Bolivian Amazon. Comparison of oxbow lake and meander scar dimensions along an inactive meander belt of the Río Mamoré (Llanos de Moxos, north-eastern Bolivia) and its modern counterpart suggests significant regional paleohydrological variability. We used these features as geomorphological and sedimentary archives to enhance our understanding of longer-term variations of the fluvial system. Late Pleistocene to Holocene hydrological changes of the Río Mamoré are inferred from: (i) the analysis of satellite imagery, (ii) discharge estimates from meander morphology, (iii) stratigraphic, and (iv) chronological information based on luminescence and radiocarbon dating. The combined data from three oxbows indicate that the now abandoned meander belt – the paleo-Mamoré – continued to be active at least until ∼5 ka, and likely even postdating 3 ka. An up to threefold increase in discharge is estimated for the modern Río Mamoré versus the paleo-Mamoré. The altered runoff regime may have triggered an avulsive shift towards the currently active Río Mamoré. The preceding increase in discharge in turn, was possibly related to a shift in climatic conditions, which changed markedly between the mid- and late Holocene in tropical South America. In addition, it may have been the indirect result of capturing the avulsive Río Grande system to the east of the Río Mamoré. Alternative explanations for the differences in dimensions of the paleo versus the modern Río Mamoré, i.e. contemporaneous activity of both rivers or alteration of site factors such as the channel/floodplain relationship, are considered to be unlikely.

New data on the Lateglacial period of SW Europe: a high resolution multiproxy record from Laguna de la Roya (NW Iberia)

High-resolution multiproxy analyses were performed on a 128 cm section of organic sediments accumulated in a small mountain lake in NW Iberia (Laguna de la Roya, 1608 m asl). The pollen stratigraphy together with radiocarbon dating provided the basis for a chronology ranging from 15,600 to 10,500 cal yr BP. Chironomid-inferred July air temperatures suggest a temperature range from 7 to 13 degrees C, also evidencing two well-established cold periods which may be equivalent to the INTIMATE stages GS-2a and GS-1. Furthermore, a number of short cold events (with summer temperatures dropping about 0.5-1 degrees C) appear intercalated within the Lateglacial Interstadial (possibly equivalent to the INTIMATE cold events GI-1d, GI-1c2 and GI-1b) and the early Holocene (possibly equivalent to the 11.2 k event). The temperature variations predicted by our reconstruction allow explaining the changes in local conditions and productivity of the lake inferred from the biological record of the same sediment core. Furthermore, they also agree with the local and regional vegetation dynamics, and the main oscillations deduced for the vegetation belts. Based on its chronology our multiproxy record indicates a similar temperature development in NW Iberia as inferred by the Greenland delta O-18 record, the marine deep-sea records off the Atlantic Iberian Margin, and other chironomid-based Lateglacial temperature reconstructions from Europe. Nevertheless, the impact of most of the less intense Lateglacial/early Holocene cold events in NW Iberia was most probably limited to very sensitive sites that were very close to ecotonal situations. Particularly, our new pollen record indicates that they were represented as three minor environmental crises occurring during the Lateglacial Interestadial in this area. The Older Dryas event (in our usage corresponding to the Aegelsee Oscillation in Central Europe and event GI-1d in central Greenland) has previously been described in this region, but its age and duration (ca 14,250-14050 cal yr BP) is now better constrained. The two subsequent stages, La Roya I (ca 13,600-13,400 cal yr BP) and La Roya II (ca 13,300-12,900 cal yr BP) have been described for first time in NW Iberia. (C) 2013 Elsevier Ltd. All rights reserved.

Distinct lake level lowstand in Lake Prespa (SE Europe) at the time of the 74 (75) ka Toba eruption

Abstract. The 74 (75) ka Toba eruption in Sumatra, Indonesia, is considered to be one of the largest volcanic events during the Quaternary. Tephra from the Toba eruption has been found in many terrestrial and marine sedimentary deposits, and acidity peaks related to the eruption have been used to synchronize ice core records from Greenland and Antarctica. Seismic profiles and sedimentological data from Lake Prespa on the Balkan Peninsula, SE Europe, indicate a lake level lowstand at 73.6±7.7 ka based on ESR dating of shells. Tephrostratigraphy, radiocarbon dating and tuning of the total organic carbon content with the NGRIP isotope record, corroborate that the lake level lowstand was a short-term event superimposed on the general cooling trend at the end of MIS 5, most likely at the onset of the Greenland Stadial GS- 20. Acknowledging that tectonic events or karst processes could have triggered this lake level lowstand, the chronological correspondence between the lowstand and the Toba eruption is intriguing. Therefore a Toba-driven short-term shift to aridity in the Balkan region, leading to lake level changes and triggering spatial expansion events in one of the lake’s most abundant benthic species, the carino mussel Dreissena presbensis, cannot be excluded.