Tectonic and climatic forcing on the Panj river system during the Quaternary

Abstract HKT-ISTP 2013 B

Deformationsanalyse und mechanische Kopplung eines aktiven fore-arcs in Raum und Zeit, Kamtschatka, Russische Föderation

Seit dem Mesozoikum wächst die kontinentale Kruste am aktiven Plattenrand von Kamtschatka durch Akkretion allochthoner Terrane. Dieses Wachstum manifestiert sich in der differenziellen Exhumierung und Hebung tektonischer Blöcke innerhalb des Akkretionskeils, parallel zum Kamtschatka- Graben. Die Kinematik der Exhumierung soll mittels strukturgeologischer und neotektonischer Deformationsanalyse erfasst und mit thermochronologischen Untersuchungen an Apatiten bis etwa ins Untere Pliozän quantifiziert werden.conferenc

Geologie, Paläontologie und Geochronologie des Eem-Beckens Neumark-Nord 2 und Vergleich mit dem Becken Neumark-Nord 1 (Geiseltal, Sachsen-Anhalt)

Den Schwerpunkt dieser Arbeit bilden die Ergebnisse sedimentologischer, palynologischer, malakologischer und chronometrischer Untersuchungen an Sedimenten aus dem Zentralbereich des Paläoseebeckens Neumark-Nord 2. Die interdisziplinären Untersuchungen an dem 11 m mächtigen Hauptprofil A und benachbarten Profilen zeigen übereinstimmend, dass die limnische Sedimentation vom Ende des Saale-Komplexes über die Eem-Warmzeit bis in die Weichsel-Kaltzeit erfolgte. Das Profil lässt Seespiegelschwankungen mit einer generellen Tendenz der Verflachung und Verlandung sowie wechselnde Sedimentationsraten erkennen. Durch die palynologischen Untersuchungen sind außerdem mit Erosion und Sedimentumlagerungen verbundene Hiaten festgestellt worden. Eine von Laurat et al. (2006) und Mania et al. (2008, 2010) im Profil ausgewiesene zusätzliche Warmzeit, die durch eine Kaltphase von der Eem-Warmzeit separiert und zudem jünger als das Interglazial von NN1 sein soll, existiert nicht. Vor allem die palynostratigraphische, aber auch die malakologische Koinzidenz der Becken NN1 und NN2 belegt die Gleichaltrigkeit der Ablagerungen. Somit ist in Neumark-Nord zwischen der Saale-Grundmoräne der Zeitz-Phase und den periglaziären Bildungen der Weichsel-Kaltzeit nur eine Warmzeit nachweisbar, das Eem. Dies wird durch neue geochronologische Daten eindeutig verifiziert. Daher können die zuletzt von Mania et al. (2010) dokumentierten Lagerungsbeziehungen, nach denen die Beckenfolge von NN2 über der von NN1 liegen soll, nicht bestätigt werden. In Neumark-Nord werden die klimatischen Besonderheiten des Mitteldeutschen Trockengebietes während der Eem-Warmzeit deutlich. Insofern bietet der Vergleich der Eem-Vorkommen von Neumark-Nord, Gröbern und Grabschütz ein Lehrbeispiel für die standortspezifische Variabilität benachbarter synchroner Warmzeitprofile.researc

The raised bogs of Mecklenburg-Vorpommern - First analysis of the investigations for the raised bog conservation programme in Mecklenburg-Vorpommern, FRG

Der gegenwärtige Arbeitsstand am Regenmoor-Schutzprogramm des Bundeslandes Mecklenburg-Vorpommern wird vorgestellt. Im Rahmen der für das Schutzprogramm notwendigen Untersuchungen wurden die Moore vegetationskundlich und hydrologisch kartiert. Zahlreiche lithostratigraphische und geochronologische Untersuchungen trugen dazu bei, die ökologische und geologische Entwicklung der Moore zu klären. Die Ergebnisse zeigen, daß eine erfolgreiche Renaturierung nur dann erfolgen kann, wenn die Moore zusammenhängend, in ihrem gesamten ehemaligen Ausmaß, d.h. auch mit den umgebenden Niedermoorbereichen vernäßt werden. Die Ergebnisse von 3 Jahren werden zusammengefaßt dargestellt.The state of a research project on preparing a raised bog conservation programme in the Mecklenburg-Vorpommem region (NE-Germany) is presented. Mapping of the vegetation and hydrological conditions of the bogs has been carried out. By the help of lithostratigraphic and geochronologic research the ecological and geological evolution of the raised bogs could be reconstructed in that region. The results show, that a successful renaturalization is only possible by rewetting the bogs over the entire former area, which includes the fen area too. The results of 3 years of research study are presented in summarized form.researchDFG, SUB Göttingen, DGM

Rates of river incision across the main tectonic units of the Pamir identified using optically stimulated luminescence dating of fluvial terraces

Calculated incision rates along the Panj, the main river of the Pamir, are used to investigate any influence by tectonics or climate on the architecture of the river. The depositional ages of Panj River terraces were calculated using optically stimulated luminescence (OSL) dating of terrace sand. Fluvial incision rates were generated by integrating the terrace depositional ages with accurate kinematic GPS measurements of terrace heights above the modern Panj. We investigated 16 terraces along the Panj at the western Pamir margin and one terrace from the Vakhsh River to the north of the Pamir. The results reveal brief periods of fluvial deposition over the past 26 kyr. The oldest Panj terrace depositional ages coincide with early MIS 2 and MIS 2/1 glaciations on the Pamir Plateau. Younger terrace ages have no apparent link with glacial cycles. Terraces with varying heights above the modern Panj at different localities yielded similar depositional ages. This suggests that local conditions have determined fluvial incision rates. Combining all of the terrace measurements, the average incision rate of the Panj over the last 26 kyr has been ~ 5.6 mm/yr. A high mean incision rate of ~ 7.3 mm/yr was calculated from terraces where the Panj has cut a steep-sided valley through the Shakhdara dome. Significantly lower incision rates (~ 2–3 mm/yr) were calculated from terraces where the Panj flows along the southern boundaries of the Shakhdara and Yazgulom domes. At those localities, graded segments of the Panj River profile and increased valley widths are indicative of local base levels. Downstream of the Yazgulom dome, river incision rates are generally lower (~ 4–5 mm/yr) than the Panj average. However, there is one exception where higher incision rates (~ 6 mm/yr) were calculated upstream of the Darvaz Fault Zone, a major tectonic feature that forms the western boundary of the Pamir. The Vakhsh River terrace to the north of the Pamir yielded a lower incision rate (~ 3 mm/yr) compared to the Panj average. Variation in incision rates along the Panj does not correspond to changes in rock type or river catchment area. Instead, incision rates appear to have been primarily influenced by river capture across the southern and central metamorphic domes of the Pamir. Wherever the Panj cuts these domes it displays a convex river profile. The combination of localized river profile convexity and changes in incision rates across the Pamir domes indicates that the dome boundaries have been active recently

Exploring the potential of luminescence methods for dating Alpine rock glaciers

Rock glaciers contain valuable information about the spatial and temporal distribution of permafrost. The wide distribution of these landforms in high mountains promotes them as useful archives for the deciphering of the environmental conditions during their formation and evolution. However, age constraints are needed to unravel the palaeoclimatic context of rock glaciers, but numerical dating is difficult. Here, we present a case study assessing the potential of luminescence techniques (OSL, IRSL) to date the inner sand-rich layer of active rock glaciers. We focus on the signal properties and the resetting of the signal prior to deposition by investigating single grains. While most quartz shows low signal intensities and problematic luminescence characteristics, K-feldspar exhibits much brighter and well-performing signals. Most signals from plagioclases do not show suitable properties. Luminescence signals far below saturation indicate distinct but differential bleaching. The finite mixture model was used to determine the prominent populations in the equivalent dose distributions. The luminescence ages represent travel times of grains since incorporation into the rock glacier and hence, minimum ages of rock glacier formation. Luminescence ages between 3 ka and 8 ka for three rock glaciers from the Upper Engadine and Albula region (Swiss Alps) agree well with independent age estimates from relative and semi-quantitative approaches. Therefore, luminescence seems to have the potential of revealing age constraints about processes related to the formation of rock glaciers, but further investigations are required for solving some of the problems remaining and reducing the dating uncertainties

Age determinations in Lena Delta

The age correlation between the three main geomorphological terraces in the Lena Delta, especially that of the second sandy terrace (Arga Island) and the third terrace (Ice Complex and underlying sands) is still being discussed, Knowledge about the age of the lee Complex and its underlying sands, and the Arga sands is necessary for understanding the past and modern structure of the delta. Geochronometrie data have been acguired for three sediment seguences from the Lena Delta by lumineseence dating using the potassium feldspar IR-OSL technique. Additionally, 14C dates are available for geochronological discussion. Typical sediments of the upper part of Arga Island as found in the area of Lake Nikolay are of Late Pleistoeene age (14.5-10.9 ka), Typical third terrace sediments from two seguenees located at the Olenyokskaya branch are older. At the profile "Nagym" sandy seguences were most probably deposited between about 65 ka and 50 ka before present. The lower part of the sandy seguence at "Kurungnakh Island" is possibly older than the sediments of the section at Nagym. However, methodological difficulties in luminescence dating (insufficient bleaching at the time of deposition) and younger 14C dates make the discussion of the results difficult