Institut für Ökosystemforschung

The AIG10 borehole provided direct access to hydraulic conditions. The first results of two open-hole pumping tests and one artesian production test are presented. From the first pumping test in the conglomerates, a hydraulic conductivity of 10−5– was derived and it was suggested that there is a closed hydraulic system bounded by the Aigion Fault zone and other faults farther north. A second pumping test, in the Olonos–Pindos limestones, showed artesian flow (water pressure of 0.5 MPa and flow of ). The transmissivity is about . Below the fault zone, pressure and flux increased, suggesting karstic water-flow conditions. Water-pressure difference of more than 0.5 MPa between the hangingwall and the footwall provides evidence that the Aigion Fault zone acts as an impervious zone. An artesian production test for the interval 708–1001 m showed a fluid pressure of >1 MPa and natural flow of . A transmissivity of 2– was determined. A preliminary conceptual hydrogeological model, containing flow parameters and flow paths, is developed, based on data from AIG10 and other wells and springs. To cite this article: V. Giurgea et al., C. R. Geoscience 336 (2004).Le forage AIG10 a permis un accès direct aux conditions hydrogéologiques du flanc sud du graben de Corinthe. Dans ce forage, on a identifié un système aquifère formé par cinq aquifères. Trois d'entre eux sont constitués de graviers et de conglomérats. Un essai de pompage dans ces derniers suggère qu'il s'agisse d'un système hydraulique fermé. Un deuxième essai de pompage, effectué dans les calcaires du compartiment supérieur de la faille d'Aigion, révèle un aquifère artésien et une transmissivité faible. Au-dessous de la zone de la faille, la pression et le débit augmentent, suggérant des conditions d'écoulement karstique. La différence de pression entre les deux compartiments prouve que la faille est presque imperméable. Un essai de production artésienne, réalisé au-dessous de la faille, a mis en évidence une haute pression ainsi qu'un débit naturel haut et constant. À partir des résultats de AIG10, on a pu proposer un modèle hydrogéologique conceptuel, qui prenne également en compte les résultats des mesures hydrologiques et géochimiques d'autres forages et sources. Pour citer cet article : V. Giurgea et al., C. R. Geoscience 336 (2004).

The island of Isla de los Estados is situated at 54.5°S, 64°W, east of Argentinian Tierra del Fuego, and is located in a sensitive geographic position in relation to the zonal circulation between Antarctica and South America. Its terrestrial records of the last deglaciation, recording atmospheric conditions but within an oceanic setting, can help to clarify changes of regional circulation patterns, both atmospheric and marine. Here, we present geochemical analyses from 16–10 ka cal BP of a peat core from Lago Galvarne Bog at the northern coast of the island, and a lake sediment core from Laguna Cascada 3 km further south. The data comprise TC, TN, loss on ignition analyses and continuous XRF scanning on both cores as well as age–depth modeling based on AMS-14C dating. Deglaciation and onset of peat formation in the coastal areas began before 16 ka cal BP followed by a rapid glacial retreat and the start of lacustrine sedimentation further inland. Data suggest initially windy conditions with permafrost succeeded by gradually warmer and wetter conditions until ca 14.5 ka cal BP. The warming trend slows down until ca 13.5 ka cal BP, followed by arid conditions culminating around 12.8 ka cal BP. Our data suggest fairly warm conditions and the establishment of denser peat and forest vegetation ca 10.6 ka cal BP, contemporaneous with the onset of the Antarctic thermal optimum. This indicates large-scale shifts in the placement of zonal flow and the Westerlies at the beginning of the Holocene.

The Atacama Desert is known to be one of the driest places on earth. However, in the study area between Ica and Nasca, South Peru (75–76°W, 14–15°S), palaeoclimate proxies show several semi-arid phases during the Holocene. A more humid period during the early Holocene favoured an open grass land, which allowed the accumulation of desert loess [Eitel, B., Hecht, S., Mächtle, B., Schukraft, G., Kadereit, A., Wagner, G., Kromer, B., Unkel, I., Reindel, M., 2005. Geoarchaeological evidence from desert loess in the Nazca-Palpa Region, Southern Peru: palaeoenvironmental changes and their impact on pre-Columbian cultures. Archaeometry, 47, 137–158.]. The Paracas and Nasca cultures existing in that region between the 9th century BC and 7th century AD had propitious conditions to evolve and to settle close to the rivers fed by the monsoonal precipitation in the Cordillera Occidental. Culminating aridity after 600 AD might have caused the collapse of the Nasca civilization. The onset of semi-arid climate towards the end of the Late Intermediate period (∼14th century AD), allowed a reoccupation of the area. Here, we present 14C and OSL data from sediments of river terraces, a debris flow and loess snails (Scutalus sp.), indicating appreciable geomorphic activity between 1390 and 1714 cal AD. This phase is isochronous to the Little Ice Age period on the northern hemisphere and to an increase in the ice accumulation on the Quelccaya glacier in the Peruvian Altiplano [Thompson, L.G., Mosley-Thompson, E., Bolzan, J.F., Koci, B.R., 1985. A 1500-year record of tropical precipitation in ice cores from the quelccaya ice cap, Peru. Science, 229, 971–973.].

Southernmost Patagonia, located at the relatively narrow passage between Antarctica and South America, is a highly sensitive region for recording meridional and zonal changes in the pattern of oceanic and atmospheric circulation. The island of Isla de los Estados, situated at 54.5°S, 64°W, east of Argentinean Tierra del Fuego, provides an exceptional possibility, to investigate terrestrial records of atmospheric conditions in an oceanic setting during the last deglaciation and the Holocene. Here we present geochemical and diatom analyses from 10 600 to c. 1500 cal BP of one sequence (LGB) with peat, lake sediments and lagoon deposits at the northern coast of the island, and a lake sediment sequence (CAS) 3 km further inland. The data comprise TC, TN, loss on ignition analyses and continuous XRF scanning as well as age–depth modeling based on AMS-14C dating on both cores. Diatom analysis of the CAS record complements the geochemical proxies. During the Holocene, our two sites have been impacted by two different forcings: changes in the regional climate regime largely influenced by the varying strength and position of the Southern Hemisphere Westerlies (SHW), while relative sea-level changes affected the deposits of the coastal site. In concert with the onset of the Antarctic thermal optimum, our data suggest fairly warm conditions and the establishment of denser peat and forest vegetation on the island c. 10 600 cal BP. Between 8500 and 4500 cal BP geochemistry and diatoms from the CAS record indicate stronger Westerlies at this latitude, which means higher wind speed or higher storm frequency and more precipitation, resulting in more pronounced surface run-off. After 4500 cal BP, the geochemical proxies and large changes in diatom assemblages indicate a decrease in precipitation, weaker winds and possibly cooler conditions, probably as an effect of weaker SHW and/or a latitudinal shift. The depositional environment of CAS changed from gyttja to peat around 1000 cal BP. At LGB, the onset of gyttja sedimentation around 7900 cal BP shows that the former wet land with peat accumulation had become a lake with a fairly rapid sedimentation. The chemical data from LGB imply a gradually increasing marine influence, probably as an effect of both rising sea level and increased impact of storms and maximum high tides. After a marine high-stand during the mid-Holocene, the LGB site returned into a peat bog again around 3400 cal BP. Our data suggest that since then relative sea level first dropped back below present sea level followed by a rise to present day sea level.

A key feature of Greece is the large amount of historical and archaeological records. The sedimentary record of the Etoliko Lagoon, Aetolia, Western Greece, offers an ideal opportunity to study human–environment interaction and to disentangle natural and anthropogenic imprints in the sedimentary record. By applying an interdisciplinary approach of combining geoscientific methods (XRF, LOI, grain size analysis) with archaeological and historical records, the 8.8 m long sedimentary sequence ETO1C reveals the palaeoenvironmental history of the lagoon and its catchment since 11,670 cal BP. With a thorough chronology based on 14C age-depth-modelling including varve counting, different evolutionary stages were put in a chronological context. These stages include a lake period (11,670–8310 cal BP) followed by a period of sporadic saltwater intrusion (8310–1350 cal BP) as a result of continuing transgression. Phases of limnic predominance associated with freshwater inflow of episodically activated distributaries (around 5230 cal BP) still occurred. By 1350 cal BP, ongoing sea level rise had connected the lagoons of Etoliko and Messolonghi and freshwater influence had ceased. With the onset of settlement activity in the Late Helladic (1700–1100 cal BC) humans took advantage of the prevailing environmental landscape. A sudden increase in coarse sedimentation correlates with the history of human occupation with its peak of prosperity from the Late Helladic until the end of the Hellenistic Period (30 cal BC).

We have analyzed an almost 14,000 year old peat sequence on the island of Isla de los Estados (55° S, 64° W), east of Tierra del Fuego, in the core of the Southern Hemisphere Westerlies. A multitude of methods have been used: high resolution 14C dating; detailed lithologic descriptions including humification degree; loss on ignition; magnetic susceptibility; bulk density; pollen and spore analysis and determination of Aeolian sand influx. By combining proxies for wind and precipitation we have been able to reconstruct how the westerlies have varied over time in the Atlantic sector of the Southern Ocean. It shows that this westerly wind belt was most intense at the onset of the record, 13,600–13,200 cal BP, coinciding with the mid to late part of the Antarctic Cold Reversal, followed by a gradual decline. At 12,200 cal BP the westerlies seem to have shifted to a position south of Tierra del Fuego and this phase, the calmest and driest period on the island throughout the sequence, ended at 10,000 cal BP when the westerlies moved equatorward again. Since then the westerlies have been present but with a variable impact on the 55° S latitude of the Atlantic. Mostly conditions have been fairly similar to today, but occasionally with a wider or narrower and/or weaker or stronger wind belt. At 7200 cal BP wind intensity began to increase and between 4500 and 3500 cal BP these southern latitudes experienced a distinct wind and precipitation maximum, both in terms of perseverance and intensity. Our results show a both wide and strong wind belt, with possible niveo-aeolian activity in Tierra del Fuego in winter, and possibly creating milder summers around the Antarctic Peninsula. In the later part of the Holocene, expansion–contraction phases of the wind belt, especially in winter, seem to have been a common phenomenon.► A record of wind and precipitation variability at 55°S back to 13.6 ka BP. ► Changes in strength and latitudinal position of southern westerlies (SHW). ► Most intense SHW in southernmost S America during the Antarctic Cold Reversal. ► SHW displaced south of Tierra del Fuego 12.2–10.0 ka BP. ► Changing SHW during the Holocene with a maximum intensity 4.5–3.5 ka BP.

Based on AMS-14C-dates we reconstruct the active phases of a characteristic earth flow in the Northern Alps.We correlate these phases with known climate fluctuations during the Holocene.The earth flow was reactivated after more than 3000 years of dormancy.The Stambach mass movement (Austria) is a large and deep-seated mass movement in the Austrian Alps. It consists of a complex and compound mass movement system. The latest major reactivation of the Stambach mass movement was initiated in 1982 by rock fall activity that triggered an earth flow, which transformed into a mud flow. Six sediment cores were taken along the entire earth flow body showing a complex mixture of rock fall blocks and earth flow material. Whenever the earth flow was active, numerous wooden remains were buried within the flow mass. Thirteen of these remains sampled from the sediment cores were radiocarbon dated. The results indicate that the first activation of the Stambach mass movement occurred at least around 9750–9900 cal BP, followed by at least three further events during the Holocene, around 6310–5650, 2320–1880, and 1600–1180 cal BP. Accumulation of toppled rock towers in the head area of the earth flow, followed by a sudden collapse and saturated, undrained loading of the earth flow body, is the main trigger for activating the earth flow. These long lasting preparatory processes make it difficult to determine certain recurrence intervals. However, our data show that the Stambach mass movement was (and most probably still can be) reactivated after more than 3000 years of dormancy.

The paper presents proxies from an interdisciplinary geoarchaeological working group. Sediment analyses and geomorphological studies, radiocarbon ages of snail shells and luminescence dating of loess allow a preliminary chronology of the environmental evolution of the eastern Atacama desert, Nazca–Palpa region (southern Peru). Until now, typical desert loess was unknown from the arid western flank of the Andes (southern Peru). The loess points to periods of more humid conditions with open grasslands at the eastern Atacama desert margin in the early and middle Holocene. In the footzone of the Andes, aridification set in before the Paracas Culture (c. 800–200 bc) evolved, but the Cordillera Occidental remained semi-arid. A second push of increasing aridity started at the latest in the Middle Nazca Period (after ad 250). During this time, the Nazca settlement centres moved upstream through the river oasis, following the eastward-shifting desert margin. It is possible that culminating aridity after ad 600 caused the collapse of the Nazca civilization. During the Late Intermediate Period (ad 1000–1400), more humid conditions favoured the massive reoccupation of the eastern Atacama up to a distance of about 40 km from the Pacific coast. Since the 14th and 15th centuries, the Palpa region has again been part of the hyper-arid Atacama. The study shows that in the Nazca–Ica region, the deep cultural changes of Pre-Columbian civilizations were not caused by catastrophic run-off of El Niño events, but by a shifting eastern desert margin due to the changing monsoonal influence.

Isla de los Estados (54° 45′S, 63° 10′–64° 46′W) lies east of the main island of Tierra del Fuego and is the southeastern-most point in Argentina. Because of its geographic position near the latitudes of the Southern Hemisphere Westerlies and the strong influence of the Antarctic Circumpolar Current (ACC), the area is suitable for paleoecological and paleoclimate research. The island is not far north of the Subantarctic Front, which limits the northern boundary of the ACC. Paleoenvironmental study in this geographic location can shed light on past changes in atmospheric and marine circulation patterns. Diatom analysis of the lower part of a sediment sequence from Laguna Cascada (54° 45′ 51.3′′S, 64° 20′ 20.07′′W) enabled inference of changing lake conditions between 16 and 11.1 cal ka BP. Between 16 and 14.4 cal ka BP fragilarioid diatom species, often a pioneer group, dominated the record. Their presence shows seasonally open-water conditions from the onset of sedimentation. In zone II (14.4–12.8 cal ka BP), the dominance of planktonic/tychoplanktonic Aulacoseira spp. might represent longer ice-free periods and windier conditions, which would have kept this heavy species suspended in the water column. This period corresponds to the Antarctic Cold Reversal, when the Southern Hemisphere Westerlies were possibly centered on the latitudes of Tierra del Fuego, resulting in windy and wet conditions. Zone III (12.8–11.1 cal ka BP) is dominated by benthic diatom taxa that are mainly associated with peat and wetland vegetation. This suggests that climate conditions had become milder and less windy, favoring aquatic productivity and terrestrial vegetation development. This change in environmental conditions may have been a consequence of the southward movement of the Southern Hemisphere Westerlies at the start of the Antarctic Holocene thermal optimum.

In drei Horizonten wurde in den Mauerer Sanden nach Kleinsäugerresten gesucht. Zusätzlich zu einer bisher schon bekannten Waldmaus-Art sowie mehreren Wühlmaus-Arten wurde erst­ mals die Spitzmaus-Gattung Sorex gefunden. Damit wird die Existenz einer 'Mauerer Waldzeit', in welcher der Homo heidelbergensis lebte, auch durch weitere Kleinsäuger bestätigt.

[On the micromammal fauna in the Middle Pleistoecene 'Mauer Sands']
We searched three horizons of the ' Mauer Sands' for micromammal remnants, In addition to a previously known species of wood mouse as well as several vole species we found the shrew mouse Sorex for the tirst time. Therewith the existence or a warm period named 'Mauer forest time' du ring which Homo heidelbergensis lived is confirmed by additional micro mammals.

As part of the lagoon barrier accretions plain characterizing the NW coast of the Peloponnese, the Kotychi Lagoon is believed to
have formed in the prograding delta of the Palaeo-Peneus River over 7000 years ago. Geochemical/sedimentological proxies-data
(XRF, grain size, OC-, IC-, C/N-analysis) combined with Bayesian age-depth-modeling revealed that from 8500 to 8000 cal BP
marine conditions were prevailing. Around 8000 cal BP, a short-lived sequence of coastline progradation and barrier accretion
created lagoonal conditions. Thus, the first chronological control for the onset of lagoon formation in coastal Elis is presented.
Pronounced lagoonal conditions developed approximately 6300 cal BP, simultaneously to the period of circum-Mediterranean
lagoon formation. A rapidly varying sedimentary record indicates a phase of geomorphological instability between 5200 and 3500
cal BP terminating with the erosional unconformity of a river channel. This evolution reflects a two-phase development: (1) Early
Holocene morphology was controlled by the postglacial sea level rise; (2) with receding of the ice sheets by mid-Holocene, the
preeminent role of the eustatic signal was overwhelmed giving local and regional processes, such as human-induced soil erosion
and climatic forcing an accentuated role. Thus, the evolution of the Elean coastline shows analogies to circum-Mediterranean
lagoon formation.

The Gulf of Corinth is one of the most active continental rift systems showing one of the highest opening rates world-wide. In 2000 the EU started to support research in this unique natural laboratory with different projects. Besides surface-exploration there are several deep drilling projects planned onshore and offshore within the Gulf-region. Therefor in summer 2002 the first continental deep drilling project, AIG 10, was carried out in the harbour area of
Aigion-city at the southern margin of the Corinth-rift....

Here, we present a well-dated terrestrial charcoal chronology covering the interval ~ 41,000–7050 cal BP and identifying the millennial-scale variability in biomass burning for the tropical Leizhou Peninsula, south China. Our results show that changes in biomass burning closely followed regional temperature and precipitation variations on orbital timescales, i.e., more biomass burning occurred during the warm/wet Marine Isotope Stage (MIS) 3, and less biomass burning occurred during the cold/dry MIS 2. Superimposed on this general trend, our charcoal record shows millennial-scale variability in biomass burning corresponding to the rapid climate changes associated with Dansgaard–Oeschger (D–O) cycles, i.e., biomass burning increased during D–O warming events, whereas biomass burning decreased during intervals of rapid cooling terminated by Heinrich events. During the cooler/drier periods, low biomass burning can be explained by the decline of vegetation productivity, whereas the warmer/wetter periods are characterized by higher biomass burning related to increasing fuel availability. Therefore, climate control can be considered as the major forcing factor of biomass burning from 41,000–7050 cal BP on both orbital and millennial timescales in the northern Leizhou Peninsula.

A well-dated palynological record spanning the interval ~ 40,500–7060 cal yr BP, retrieved from a peatland on the Leizhou Peninsula in south China, clearly shows regional vegetation and climate changes during the last glacial period. Pollen data showed that the study region was mainly covered by subtropical evergreen trees during Marine Isotope Stage 3 (MIS 3), indicating a subtropical climate with relatively high temperature and precipitation. During MIS 2, subtropical evergreen-deciduous forest with large areas of grassland occurred, implying cooler and drier conditions. Some tropical forest elements increased during the early Holocene, indicating a warm and wet trend. Several millennial-scale oscillations of the pollen records appeared to correlate with the cold anomalies in the North Atlantic region. Our records agree well with many records from other regions, but they are a bit different than that inferred from the neighboring Huguang Maar Lake. Furthermore, our results suggest that the vegetation surrounding Xialu peatland was strongly influenced by the migration of the intertropical convergence zone (ITCZ) and variability in the East Asian summer monsoon (EASM). Changes of atmospheric CO2 concentration (pCO2) levels may have also affected the long-term vegetation changes in the study region