TY - THES A1 - Schodlok, Martin C. T1 - Quantitative Analysen magmatischer Gesteine mittels reflexionsspektroskopischer Infrarot-Messungen Y1 - 2004 UR - http://www.gfz-potsdam.de/bib/pub/str0410/0410.htm UR - https://nbn-resolving.org/urn:nbn:de:kobv:b103-04100 ER - TY - JOUR A1 - Beauval, Céline A1 - Scotti, O. T1 - Quantifying sensitivities of PSHA for France to earthquake catalog uncertainties, truncation of ground-motion variability, and magnitude limits N2 - The results of this study clearly identify four key parameters controlling the estimation of probabilistic seismic hazard assessment (PSHA) in France in the framework of the Cornell-McGuire method. Results in terms of peak ground acceleration demonstrate the equally high impact, at all return periods, of the choice of truncation of the predicted ground-motion distribution (at + 2sigma) and of the choice between two different magnitude-intensity correlations. The choice of minimum magnitude (3.5/4.5) on hazard estimates can have an important impact at small return periods (<1000 years), whereas the maximum magnitude (6.5/7.0), on the other hand, is not a key parameter even at large return periods (10,000 years). This hierarchy of impacts is maintained at lower frequencies down to 5 Hz. Below 5 Hz, the choice of the maximum magnitude has a much greater impact, whereas the impact due to the choice of the minimum magnitude disappears. Moreover, variability due to catalog uncertainties is also quantified; these uncertainties that underly all hazard results can engender as high a variability as the controlling parameters. Parameter impacts, calculated at the centers of each source zone, show a linear trend with the seismicity models of the zone, demonstrating the lack of contributions coming from neighboring zones. Indeed, the region of influence that contributes to the PSHA estimate at a given site decreases with increasing return periods. The resulting overall variability in hazard estimates due to input uncertainties is quantified through a logic tree, obtained coefficients of variation vary between 10% and 20%. Until better physical models are obtained, the uncertainty on hazard estimates may be reduced by working on an appropriate magnitude-intensity correlation Y1 - 2004 SN - 0037-1106 ER - TY - BOOK A1 - Wilson, M. A1 - Neumann, Else Ragnhild A1 - Davies, G. R. A1 - Timmerman, Martin Jan A1 - Heeremans, Michel A1 - Larsen, Bjoern Tore T1 - Permo-carboniferous magmatism and rifting in Europe T3 - Geological Society special publication Y1 - 2004 UR - http://www.geolsoc.org.uk/template.cfm?name=bookshop_details&action=details&id=302 SN - 1-86239-152-1 VL - 223 PB - Geological Society CY - London ER - TY - THES A1 - Demory, François T1 - Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia) N2 - Der Baikalsee ist ein ideales Klimaarchiv für die Mitte Eurasiens. In dieser Arbeit wurde gesteinsmagnetische und paleomagnetische Analysen an hemipelagischen Sequenzen von vier Lokationen analysiert. Die Kerne erreichen ein Alter von maximal 300 ky. In Kombination mit TEM, XRD, XRF und geochemischen Analysen zeigt die gesteinsmagnetische Studie, dass detritischer Magnetit das magnetische Signal der glazialen Sedimente dominiert. Die magnetischen Signale der interglazialen Sedimente wurden durch diagenetische Prozesse verändert. Mittels HIRM können Hämatit und Goethit quantifiziert werden. Diese Methode eignet sich, den detritischen Eintrag in den Baikalsee abzuschätzen. Relative Paleointensitäten des Erdmagnetfeldes ergaben reproduizerbare Muster, welche in Korrelation mit gutdatierten Referenzproben die Ableitung eines alternativen Altersmodells für die Datierung der Baikalsedimente ermöglichten. Bei Anwendung des paleomagnetischen Altersmodells beobachtet man, dass die Abkühlung im Baikalgebiet und im Oberflächenwasser des Nordatlantiks wie sie aus den δ18 O-Werten planktonischer Foraminiferen abgeleitet werden kann, zeitgleich ist. Wird das aus benthischen δ18 O-Werten abgeleitete Altermdodell auf den Baikalsee angewandt, ergibt sich eine deutliche Zeitverschiebung. Das benthische Altersmodell repräsentiert die globale Veränderung des Eisvolumens, welche später als die Vänderung der Oberflächenwassertemperatur auftritt. Die Kompilation paleomagnetischer Kurven ergab eine neue relative Paleointensitätskurve “Baikal 200”. Mittels Korngrössenanalyse des Detritus konnten drei Faziestypen mit unterschiedlicher Sedimentationsdynamik unterschieden werden: 1) Glaziale Peroiden werden durch hohe Tongehalte infolge von Windeintrag und durch grobe Sandfraktion mittels Transport durch lokale Winde über das Eis charakterisiert. Dieser Faziestyp deutet auf arides Klima. 2) Während der Glazial/Interglazial-Übergänge steigt die Siltfraktion an. Dies deutet auf erhöhte Feuchtigkeit und damit verbunden erhöhte Sedimentdynamik. Windtransport und in den Schnee der Eisdecke eingetragener Staub sind die vorherrschenden Prozesse, welche den Silt in hemipelagischer Position zur Ablagerung bringen. 3) Während des klimatischen Optimum des Eeemian werden Grösse und Quantität des Silts minimal, was auf eine geschlossene Vegetationsdecke im Hinterland deutet. N2 - Lake Baikal provides an excellent climatic archive for Central Eurasia as global climatic variations are continuously depicted in its sediments. We performed continuous rock magnetic and paleomagnetic analyses on hemipelagic sequences retrieved from 4 underwater highs reaching back 300 ka. The rock magnetic study combined with TEM, XRD, XRF and geochemical analyses evidenced that a magnetite of detrital origin dominates the magnetic signal in glacial sediments whereas interglacial sediments are affected by early diagenesis. HIRM roughly quantifies the hematite and goethite contributions and remains the best proxy for estimating the detrital input in Lake Baikal. Relative paleointensity records of the earth′s magnetic field show a reproducible pattern, which allows for correlation with well-dated reference curves and thus provides an alternative age model for Lake Baikal sediments. Using the paleomagnetic age model we observed that cooling in the Lake Baikal region and cooling of the sea surface water in the North Atlantic, as recorded in planktonic foraminifera δ18 O, are coeval. On the other hand, benthic δ18 O curves record mainly the global ice volume change, which occurs later than the sea surface temperature change. This proves that a dating bias results from an age model based on the correlation of Lake Baikal sedimentary records with benthic δ18 O curves. The compilation of paleomagnetic curves provides a new relative paleointensity curve, “Baikal 200”. With a laser-assisted grain size analysis of the detrital input, three facies types, reflecting different sedimentary dynamics can be distinguished. (1) Glacial periods are characterised by a high clay content mostly due to wind activity and by occurrence of a coarse fraction (sand) transported over the ice by local winds. This fraction gives evidence for aridity in the hinterland. (2) At glacial/interglacial transitions, the quantity of silt increases as the moisture increases, reflecting increased sedimentary dynamics. Wind transport and snow trapping are the dominant process bringing silt to a hemipelagic site (3) During the climatic optimum of the Eemian, the silt size and quantity are minimal due to blanketing of the detrital sources by the vegetal cover. T2 - Paleomagnetic dating of climatic events in Late Quaternary sediments of Lake Baikal (Siberia) KW - Paleomagnetismus KW - Klima KW - Sedimentationsdynamik KW - diagenetische Prozesse KW - Paleomagnetism KW - climate KW - sedimentary dynamics KW - diagenesis Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001720 ER - TY - JOUR A1 - Thomas, R. A1 - Förster, Hans-Jürgen A1 - Rickers, Karen A1 - Webster, J. D. T1 - Origin and evolution of extremely F-rich hydrous melt fractions and hydrothermal fluids during differentiation of highly evolved tin-granite magmas Y1 - 2004 SN - 0016-7037 ER - TY - JOUR A1 - Letawe, G. A1 - Courbin, F. A1 - Magain, P. A1 - Hilker, M. A1 - Jablonka, P. A1 - Jahnke, Knud A1 - Wisotzki, Lutz T1 - On-axis spectroscopy of the z=0.144 radio-loud quasar HE 1434-1600 : an elliptical host with a highly ionized ISM N2 - VLT on-axis optical spectroscopy of the z = 0.144 radio-loud quasar HE 1434-1600 is presented. The spatially resolved spectra of the host galaxy are deconvolved and separated from those of the central quasar in order to study the dynamics of the stars and gas as well as the physical conditions of the ISM. We find that the host of HE 1434-1600 is an elliptical galaxy that resides in a group of at least 5 member galaxies, and that most likely experienced a recent collision with its nearest companion. Compared with other quasar host galaxies, HE 1434-1600 has a highly ionized ISM. The ionization state corresponds to that of typical Seyferts, but the ionized regions are not distributed in a homogeneous way around the QSO, and are located preferentially several kiloparsecs away from it. While the stellar absorption lines do not show any significant velocity field, the gas emission lines do. The observed gas velocity field is hard to reconcile with dynamical models involving rotating disk. modified Hubble laws or power laws, that all require extreme central masses (M > 10(9) M-circle dot) to provide only poor fit to the data. Power law models, which best fit the data, provide a total mass of M(<10 kpc) = 9.2 x 10(10) M-&ODOT;. We conclude that the recent interaction between HE 1434-1600 and its closest companion has strongly affected the gas velocity and ionization state, from the center of the galaxy to its most external parts Y1 - 2004 ER - TY - JOUR A1 - Scherbaum, Frank A1 - Cotton, Fabrice A1 - Smit, P. T1 - On the use of response spectral-reference data for the selection and ranking of ground-motion models for seismic-hazard analysis in regions of moderate seismicity : the case of rock motion N2 - The use of ground-motion-prediction equations to estimate ground shaking has become a very popular approach for seismic-hazard assessment, especially in the framework of a logic-tree approach. Owing to the large number of existing published ground-motion models, however, the selection and ranking of appropriate models for a particular target area often pose serious practical problems. Here we show how observed around-motion records can help to guide this process in a systematic and comprehensible way. A key element in this context is a new, likelihood based, goodness-of-fit measure that has the property not only to quantify the model fit but also to measure in some degree how well the underlying statistical model assumptions are met. By design, this measure naturally scales between 0 and 1, with a value of 0.5 for a situation in which the model perfectly matches the sample distribution both in terms of mean and standard deviation. We have used it in combination with other goodness-of-fit measures to derive a simple classification scheme to quantify how well a candidate ground-rnotion-prediction equation models a particular set of observed-response spectra. This scheme is demonstrated to perform well in recognizing a number of popular ground-motion models from their rock-site- recording, subsets. This indicates its potential for aiding the assignment of logic-tree weights in a consistent and reproducible way. We have applied our scheme to the border region of France, Germany, and Switzerland where the M-w 4.8 St. Die earthquake of 22 February 2003 in eastern France recently provided a small set of observed-response spectra. These records are best modeled by the ground-motion-prediction equation of Berge-Thierry et al. (2003), which is based on the analysis of predominantly European data. The fact that the Swiss model of Bay et al. (2003) is not able to model the observed records in an acceptable way may indicate general problems arising from the use of weak-motion data for strong-motion prediction Y1 - 2004 SN - 0037-1106 ER - TY - JOUR A1 - Hinzen, K. G. A1 - Weber, B. A1 - Scherbaum, Frank T1 - On the resolution of H/V measurements to determine sediment thickness, a case study across a normal fault in the Lower Rhine Embayment, Germany N2 - In recent years, H/V measurements have been increasingly used to map the thickness of sediment fill in sedimentary basins in the context of seismic hazard assessment. This parameter is believed to be an important proxy for the site effects in sedimentary basins (e.g. in the Los Angeles basin). Here we present the results of a test using this approach across an active normal fault in a structurally well known situation. Measurements on a 50 km long profile with 1 km station spacing clearly show a change in the frequency of the fundamental peak of H/V ratios with increasing thickness of the sediment layer in the eastern part of the Lower Rhine Embayment. Subsequently, a section of 10 km length across the Erft-Sprung system, a normal fault with ca. 750 m vertical offset, was measured with a station distance of 100 m. Frequencies of the first and second peaks and the first trough in the H/V spectra are used in a simple resonance model to estimate depths of the bedrock. While the frequency of the first peak shows a large scatter for sediment depths larger than ca. 500 m, the frequency of the first trough follows the changing thickness of the sediments across the fault. The lateral resolution is in the range of the station distance of 100 m. A power law for the depth dependence of the S-wave velocity derived from down hole measurements in an earlier study [Budny, 1984] and power laws inverted from dispersion analysis of micro array measurements [Scherbaum et al., 2002] agree with the results from the H/V ratios of this study Y1 - 2004 SN - 1363-2469 ER - TY - JOUR A1 - Holschneider, Matthias A1 - Teramo, A. A1 - Bottari, A. A1 - Termini, D. T1 - On the relevance of the spatial distribution of events for seismic hazard evaluation N2 - Seismic hazard evaluation is proposed by a methodological approach that allows the study of the influence of different modelling assumptions relative to the spatial and temporal distribution of earthquakes on the maximum values of expected intensities. In particular, we show that the estimated hazard at a fixed point is very sensitive to the assumed spatial distribution of epicentres and their estimators. As we will see, the usual approach, based on uniformly distributing the epicentres inside each seismogenic zone is likely to be biased towards lower expected intensity values. This will be made more precise later. Recall that the term "bias" means, that the expectation of the estimated quantity ( taken as a random variable on the space of statistics) is different from the expectation of the quantity itself. Instead, our approach, based on an estimator that takes into account the observed clustering of events is essentially unbiased, as shown by a Monte-Carlo simulation, and is configured on a 11011-isotropic macroseismic attenuation model which is independently estimated for each zone Y1 - 2004 SN - 0921-030X ER - TY - JOUR A1 - Scherbaum, Frank A1 - Schmedes, J. A1 - Cotton, Fabrice T1 - On the conversion of source-to-site distance measures for extended earthquake source models N2 - One of the major challenges in engineering seismology is the reliable prediction of site-specific ground motion for particular earthquakes, observed at specific distances. For larger events, a special problem arises, at short distances, with the source-to-site distance measure, because distance metrics based on a point-source model are no longer appropriate. As a consequence, different attenuation relations differ in the distance metric that they use. In addition to being a source of confusion, this causes problems to quantitatively compare or combine different ground- motion models; for example, in the context of Probabilistic Seismic Hazard Assessment, in cases where ground-motion models with different distance metrics occupy neighboring branches of a logic tree. In such a situation, very crude assumptions about source sizes and orientations often have to be used to be able to derive an estimate of the particular metric required. Even if this solves the problem of providing a number to put into the attenuation relation, a serious problem remains. When converting distance measures, the corresponding uncertainties map onto the estimated ground motions according to the laws of error propagation. To make matters worse, conversion of distance metrics can cause the uncertainties of the adapted ground-motion model to become magnitude and distance dependent, even if they are not in the original relation. To be able to treat this problem quantitatively, the variability increase caused by the distance metric conversion has to be quantified. For this purpose, we have used well established scaling laws to determine explicit distance conversion relations using regression analysis on simulated data. We demonstrate that, for all practical purposes, most popular distance metrics can be related to the Joyner-Boore distance using models based on gamma distributions to express the shape of some "residual function." The functional forms are magnitude and distance dependent and are expressed as polynomials. We compare the performance of these relations with manually derived individual distance estimates for the Landers, the Imperial Valley, and the Chi-Chi earthquakes Y1 - 2004 SN - 0037-1106 ER - TY - JOUR A1 - Halfar, Jochen A1 - Godinez-Orta, Lucio A1 - Mutti, Maria A1 - Valdez-Holguin, J. E. A1 - Borges, Jose M. T1 - Nutrient and temperature controls on modern carbonate production : an example from the Gulf of California, Mexico N2 - In addition to salinity and temperature, nutrient concentrations in surface waters are known to have a significant impact on distribution of carbonate-producing biota, but have never been quantitatively evaluated against different temperatures along a latitudinal transect. The western coast of the Gulf of California, Mexico, presents a natural laboratory for investigating the influence of oceanographic parameters such as salinity, temperature, and chlorophyll a, a proxy for nutrients, on the composition of a range of modern heterozoan and photozoan carbonate environments along a north-south latitudinal gradient spanning the entire warm-temperate realm (29degreesN-23degreesN). Chlorophyll a, measured in situ at half-hour resolution, is highly variable throughout the year due to short-term upwelling, and increases significantly from the southern to northern Gulf of California. Salinity, in contrast, fluctuates little and remains at an average of 35%. From south to north, carbonate production ranges from oligotrophic- mesotrophic, coral reefdominated shallow-water areas (minimum temperature 18.6 degreesC) through mesotrophic-eutrophic, red algal-dominated, inner-shelf carbonate production in the central gulf (minimum temperature 16 degreesC), and to molluscan-bryozoan, eutrophic inner- to outer-shelf environments (minimum temperature 13.7 degreesC). The Gulf of California data, supplemented with oceanographic and compositional information from a database compiled from a spectrum of modern carbonate systems worldwide, demonstrates the significance of nutrient control in the formation of heterozoan, photozoan, and transitional heterozoan-photozoan carbonate systems and serves as a basis for more accurately interpreting fossil carbonates Y1 - 2004 SN - 0091-7613 ER - TY - JOUR A1 - von Seckendorff, V. A1 - Timmerman, Martin Jan A1 - Kramer, W. A1 - Wrobel, P. T1 - New 40Ar/39Ar ages and geochemistry of late Carboniferous to early Permian lamprophyres and related volcanic rocks in the Saxothuringian Zone of the Variscan Orogen (Germany) Y1 - 2004 ER - TY - JOUR A1 - Bowman, Dan A1 - Korjenkov, Andrey A1 - Porat, Naomi A1 - Czassny, Birka T1 - Morphological response to quaternary deformation at an intermontane basin piedmont, the northern Tien Shan, Kyrghyzstan N2 - The Tien Shan is a most active intracontinental mountain-building range with abundant Quaternary fault-related folding. In order to improve our understanding of Quaternary intermontane basin deformation, we investigated the intermontane Issyk-Kul Lake area, an anticline that was up-warped through the piedmont cover, causing partitioning of the alluvial fan veneer. To follow the morphological scenario during the warping process, we relied on surface-exposed and trenched structures and on alluvial fans and bajadas as reference surfaces. We used air photos and satellite images to analyze the spatial -temporal morphological record and determined the age of near surface sediments by luminescence dating. We demonstrate that the up-warped Ak-Teke hills are a thrust-generated subdued anticline with strong morphological asymmetry which results from the coupling of the competing processes of up-warp and erosional feedback. The active creeks across the up-warped anticline indicate that the antecedent drainage system kept pace with the rate of uplift. The rivers which once sourced the piedmont, like the Toru-Aygyr, Kultor and the Dyuresu, became deeply entrenched and gradually transformed the study area into an abandoned morphological surface. The up-warp caused local lateral drainage diversion in front of the northern backlimb and triggered the formation of a dendritic drainage pattern upfan. Luminescence dating suggest that the period of up-warp and antecedent entrenchment started after 157 ka. The morphologically mature study area demonstrates the response of fluvial systems to growing folds on piedmont areas, induced by a propagating frontal fold at a thrust belt edge, following shortening. (C) 2004 Elsevier B.V All rights reserved Y1 - 2004 SN - 0169-555X ER - TY - JOUR A1 - Förster, Hans-Jürgen A1 - Rhede, Dieter T1 - Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : III. First indication of complete miscibility between tennantite and giraudite Y1 - 2004 ER - TY - JOUR A1 - Förster, Hans-Jürgen T1 - Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : II: Hessite, Ag2Te, and native Te (?), the first tellurium minerals N2 - Hessite, Ag2Te, and native tellurium (?) constitute two, previously unknown tellurium species within the complex mineral assemblage at Niederschlema-Alberoda, Erzgebirge, Germany. Hessite is always intimately associated with clausthalite and has a composition close to ideal stoichiometry. The mean empirical formula is (Ag1.98Sb0.01)(1.99)(Te0.96Se0.05)(1.01). Paragenetic relations and thermodynamic data suggest that hessite crystallized in equilibrium with clausthalite, berzelianite, and tiemannite under conditions of almost identical, high fugacitities of Se-2 and Te-2, which very locally were approached in the main selenide stage of Jurassic age. Native tellurium (?) formed as replacement product of hessite. Niederschlema-Alberoda provides the first record of hessite from an uranium deposit worldwide. Hessite and native Te are the first tellurium minerals reported from the Erzgebirge metallogenic province Y1 - 2004 ER - TY - JOUR A1 - Förster, Hans-Jürgen A1 - Rhede, Dieter A1 - Tischendorf, Gerhard T1 - Mineralogy of the Niederschlema-Alberoda U-Se-polymetallic deposit, Erzgebirge, Germany : I. Jolliffeite, NiAsSe, the rare Se-dominant analogue of gersdorffite N2 - The Niederschlema-Alberoda uranium deposit, in the Erzgebirge region of Germany, contains an uncommon assemblage of metallic minerals, in particular selenides, sulfides, arsenides, tellurides, and native elements, in addition to uraninite and coffinite. The complex mineralogy resulted from the superposition of several mineralizing events over the time interval from the Permian to the Cretaceous; these events introduced and redeposited a great variety of metallic elements within the hydrothermal uranium deposit (Pb, Ag, Cu, Hg, Tl, Bi, Co, Ni, As, Sb, Se, S, Te). One of the exotic minerals is jolliffeite, an arsenoselenide with end-member composition NiAsSe, so far only known from Lake Athabasca, Saskatchewan, Canada. A single, small, anhedral grain of jolliffeite from Niederschlema-Alberoda is included and partly replaced by sulfurian eskebornite. Associated minerals comprise hematite, Ni-Co-Se-bearing lollingite, clausthalite, tiemannite, mercurian hakite-giraudite solid solutions, sulfurian berzelianite, sulfurian umangite, hessite, Ni-Co-As-bearing pyrite, and Se-rich chalcopyrite. The sulfurian jolliffeite has the empirical formula (Ni0.85Cu0.09Co0.05Fe0.02Ag0.01)Sigma(1.02)As(0.98)(Se0.77S0.23)(Sigma1. 00) and differs from type jolliffeite mainly by substantial substitution of Cu (2.6-3.3 wt.%) for Ni and S (3.2-4.1 wt.%) for Se. Substantial S-for-Se substitution in jolliffeite implies extensive and probably complete miscibility between NiAsSe and its S-dominant analogue, gersdorffite-Pa3 (NiAsS). We suggest that a localized accumulation of Ni and As in the Se-(S)-bearing hydrothermal fluid gave rise to the crystallization of jolliffeite at some rare locations at a late stage of formation of the Jurassic selenide assemblage Y1 - 2004 ER - TY - JOUR A1 - Nabelek, Peter I. A1 - Wilke, Max A1 - Huff, T. A. T1 - Methane production during metamorphism of graphitic pelites, Black Hills, USA Y1 - 2004 SN - 0016-7037 ER - TY - JOUR A1 - Malischewsky, Peter G. A1 - Scherbaum, Frank T1 - Love's formula and H/V-ratio (ellipticity) of Rayleigh waves N2 - The ellipticity of Rayleigh surface waves, which is an important parameter characterizing the propagation medium, is studied for several models with increasing complexity. While the main focus lies on theory, practical implications of the use of the horizontal to vertical component ratio (H/V-ratio) to Study the subsurface structure are considered as well. Love's approximation of the ellipticity for an incompressible layer over an incompressible half-space is critically discussed especially concerning its applicability for different impedance contrasts. The main result is an analytically exact formula of H/V for a 2-layer model of compressible media, which is a generalization of Love's formula. It turns out that for a limited range of models Love's approximation can be used also in the general case. (C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0165-2125 ER - TY - JOUR A1 - Bowman, Dan A1 - Korjenkov, Andrey A1 - Porat, Naomi T1 - Late-Pleistocene seismites from Lake Issyk-Kul, the Tien Shan Range, Kyrghyzstan N2 - The aim of the study is to record the occurrence of sediment deformation structures in one of the tectonically most active areas on the globe, the Tien Shan range in Central Asia and to examine the significance of the deformations as indicators of palaeoseismicity. Soft-sediment deformation structures in form of balls and pseudo-nodules are exposed in the Issyk-Kul basin, within interfingering beds of shallow lacustrine, beach and fluviatile origin. Additional deformation structures that were encountered are: a complex and chaotic folded structure, giant balls and a "pillar" structure which has not been previously reported, where marl intrudes down into coarse pebbley sand and forms pillar morphology. Liquefaction features and bedforms related to storm and breaking waves were not encountered. Neither was there evidence of turbidites. Seven field criteria for relating soft-sediment deformation to palaeoseismic triggering provide strong evidence for a seismic origin of the deformation structures. Empirical relationships between magnitude and the maximum distance from an epicenter to liquefaction sites make the active epicentral zone north of Lake Issyk- Kul, with its frequent high magnitude events, the most favorable source for the deformation structures. Luminescence dating of the sediments gives a time window of 26 +/- 2.1 to 10.5 +/- 0.7 ka BP, indicating latest Pleistocene seismic activity.(C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0037-0738 ER - TY - THES A1 - Bookhagen, Bodo T1 - Late quaternary climate changes and landscape evolution in the Northwest Himalaya : geomorphologic processes in the Indian Summer Monsoon Domain N2 - The India-Eurasia continental collision zone provides a spectacular example of active mountain building and climatic forcing. In order to quantify the critically important process of mass removal, I analyzed spatial and temporal precipitation patterns of the oscillating monsoon system and their geomorphic imprints. I processed passive microwave satellite data to derive high-resolution rainfall estimates for the last decade and identified an abnormal monsoon year in 2002. During this year, precipitation migrated far into the Sutlej Valley in the northwestern part of the Himalaya and reached regions behind orographic barriers that are normally arid. There, sediment flux, mean basin denudation rates, and channel-forming processes such as erosion by debris-flows increased significantly. Similarly, during the late Pleistocene and early Holocene, solar forcing increased the strength of the Indian summer monsoon for several millennia and presumably lead to analogous precipitation distribution as were observed during 2002. However, the persistent humid conditions in the steep, high-elevation parts of the Sutlej River resulted in deep-seated landsliding. Landslides were exceptionally large, mainly due to two processes that I infer for this time: At the onset of the intensified monsoon at 9.7 ka BP heavy rainfall and high river discharge removed material stored along the river, and lowered the baselevel. Second, enhanced discharge, sediment flux, and increased pore-water pressures along the hillslopes eventually lead to exceptionally large landslides that have not been observed in other periods. The excess sediments that were removed from the upstream parts of the Sutlej Valley were rapidly deposited in the low-gradient sectors of the lower Sutlej River. Timing of downcutting correlates with centennial-long weaker monsoon periods that were characterized by lower rainfall. I explain this relationship by taking sediment flux and rainfall dynamics into account: High sediment flux derived from the upstream parts of the Sutlej River during strong monsoon phases prevents fluvial incision due to oversaturation the fluvial sediment-transport capacity. In contrast, weaker monsoons result in a lower sediment flux that allows incision in the low-elevation parts of the Sutlej River. N2 - Die Indisch-Eurasische Kontinentalkollision ist ein beeindruckendes Beispiel für weitreichenden, tektonisch kontrollierten klimatischen Einfluss. Um den Einfluss von klimatisch bedingter Erosion auf die Orogenese zu testen, habe ich erosive Oberflächenprozesse, Monsunvariationen und fluviatilen Massentransfer auf verschiedenen Zeitscheiben analysiert. Um genaue Niederschläge auf einem grossen Raum zu quantifizieren, habe ich durch Wettersatelliten aufgezeichnete passive Mikrowellendaten für die letzten zehn Jahre untersucht. Erstaunlicherweise variiert der Niederschlag nur wenig von Jahr zu Jahr und ein Großteil des Regens wird durch orographische Effekte gesteuert. Im Jahre 2002 allerdings, habe ich ein abnormal starkes Monsunjahr feststellen können. Zu dieser Zeit ist der Monsunniederschlag weiter in das Gebirge vorgedrungen und hat viele Massenbewegungen wie z.B. Schuttströme und Muren ausgelöst. Dabei verdoppelten sich die Erosionsraten im Einzugsgebiet. Ich zeige anhand von Satellitenbildern, aufgenommen vor und nach dem Monsun, dass sich hierbei vor allen Dingen kleine, neue Flußläufe entwickeln. In höher gelegenen, normalerweise trockenen Gebieten findet man auch Überreste von enormen Bergstürzen und dahinter aufgestauten Seen. Datierungen dieser geomorphologischen Phänomene zeigen, dass sie nur in zwei Phasen während der letzten 30.000 Jahre auftreten: Im späten Pleistozän vor rund 27.000 Jahren und im frühen Holozän vor 8000 Jahre. Diese Zeiten sind durch einen starken Monsun, der durch die Insolation kontrolliert wird, gekennzeichnet. Analog zur Niederschlagsverteilung im Jahre 2002 ist der Monsun aber nicht nur für ein Jahr, sondern mehrere hundert oder tausend Jahre lang kontinuierlich in die heute ariden Gebiete vorgedrungen. Der erhöhte Porenwasserdruck und die erstarkten Flüsse lösten dann durch laterale Unterschneidung große Bergstürze aus, die zu keiner anderen Zeit beobachtet wurden. Die temporären Becken in den Hochlagen, die durch Bergstürze entstanden sind, entstehen in Feuchtphasen und werden in schwächeren Monsunphasen von Flüssen abgetragen und verdeutlicht die komplexe Beziehung zwischen Klima und Massentransfer verdeutlicht. ---- Anmerkung: Der Autor wurde 2005 mit dem 7. Publikationspreis des Leibniz-Kollegs Potsdam für Nachwuchswissenschaftler/innen in Naturwissenschaften ausgezeichnet. T2 - Late quaternary climate changes and landscape evolution in the Northwest Himalaya : geomorphologic processes in the Indian Summer Monsoon Domain KW - Monsun KW - Himalaja KW - Klima KW - Indien KW - Bergstürze KW - Geomorphologie KW - Asian monsoon KW - Himalaya KW - climate KW - landslides KW - geomorphology Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001956 ER -