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SESSION NO. 9 is closely coupled with facies distribution of marine or nonmarine deposits, the geometry of regional unconformities and drainage patterns of syndepositional fluvial systems. It has direct impact on the regional distribution of today’s geopotentials of these deposits, e. g. for hydrocarbon exploration, mineral water resources, CO 2 sequestration, or industrial minerals. During the last years, the Geological Survey of Baden-Wuerttemberg (Germany) has improved the resolution of 3D modeling on a regional scale. From this modeling a consistent set of isopach maps and cross sections has been derived. The lateral scale of the thickness variations in Late Permian to late Jurassic epicontinental sediments ranges from local sinks and uplifts only a few kilometres across to intrabasinal zones of retarded or increased subsidence 10 - 100 km wide. Their position and orientation has remained stable over most of the studied time span, i. e., for more than 100 Ma, but variations in subsidence rates were not in phase at different locations. Temporal variations of differential subsidence between neighbouring locations range in scale from relatively short local subsidence pulses within single 100 ka or 400 ka depositional cycles to long-term spatial trends of thickness gradients over several biostratigraphic zones and even stages. Yet, temporal variability and spatial differentiation of these isopach anomalies and larger subsidence structures are not in accordance with simple thermal subsidence after an initial basin-forming tectonic event. We interpret these isopach structures as near-surface reflection of slow but ongoing shear along older, large-scale basement shear zones. The relevance of this long intracontinental deformation to paleogeographic reconstruction of plate boundaries and outlines has yet to be investigated. 9-9 BTH 27 Nitsch, Edgar CLIMATIC VS. TECTONIC CONTROL ON FACIES AND SALINITY CHANGES IN AN EOCENE RIFT LAKE, UPPER RHINE GRABEN, CENTRAL EUROPE NITSCH, Edgar1 , WIELANDT-SCHUSTER, Ulrike1 , RUPF, Isabel1 , and BECCALETTO, Laurent2 , (1) Landesamt für Geologie, Rohstoffe und Bergbau, RP Freiburg, Albertstr. 5, Freiburg i. Br, 79095, Germany, Edgar.Nitsch@rpf.bwl.de, (2) Geology Division, BRGM- French Geological Survey, 3 av. Cl. Guillemin, Orléans, 45060, France The Upper Rhine Graben (URG) is a complex rift and wrench basin about 300 km long, 35 to 50 km wide and filled with up to 3500 m of Eocene to Quaternary sediments. Middle to Late Eocene lacustrine and saline deposits cover an area of c. 7500 km² of the central and southern segment of the URG. Thicknesses vary from a few metres of palustrine limestone to more than 1000 m of halite-bearing marls. Lithofacies associations include bedded halite-bituminous marl alternations with salic paleosols, laminated marls with poor freshwater fauna, partly with intercalated paleosol horizons, poorly bedded marls with paleosols and sandstone beds, and palustrine limestone with pisolites and freshwater gastropods. A marginal facies belt of cyclic channelized alluvial conglomerates, sandstones and rooted overbank mudstones is typically only a few kilometres wide and rapidly replaced by block conglomerates of steeply sloped fandelta deposits close to the rift margins. There is a first-order shift of facies boundaries in the Eocene succession, indicating rapid transgressive drowning of the internal parts of the basin in the Lutetian and successive progradation of fluviolacustrine environments during the Priabonian. Paleosol facies and fossil content do not show significant changes in the overall climate regime over this transgressiveregressive cycle, spanning almost 10 Ma. Thus, we attribute this first-order cycle trend mainly to early syn-rift tectonics creating accommodation space and its subsequent autocyclic fill-up. In any of these facies there is evidence for high-frequency cyclic variations in lake level and salinity, e. g. by alternations of halite deposits and fossiliferous freshwater marls, recurring pedogenic overprint on laminated hypolimnion deposits, and subaqueous green clay intercalations within successions of palustrine carbonates. They suggest rapid lake level oscillations between deep freshwater lake phases and intense droughts, reducing the openwater surface to a small and shallow salt lake in the deepest parts of the Graben. The time scale of these oscillations is poorly constrained. According to the maturity of the paleosols, time intervals seem to represent cycles well within the Milankovich frequency band, i. e., 104 to 105 yr, and thus suggest a climatic control on these small-scale cycles. 9-10 BTH 28 Bebiolka, Anke CHARACTERISTICS OF UPPER PALEOZOIC AND MESOZOIC SEDIMENTS AS DEPICTED FROM BOREHOLE EVIDENCE IN THE GERMAN NORTH SEA BASIN BEBIOLKA, Anke, Federal Institute for Geosciences and Natural Resources, Stilleweg 2, Hannover, 30655, Germany, anke.bebiolka@bgr.de and KUHLMANN, Gesa, Federal Institute for Geosciences and Natural Resources, Branch office Berlin, Wilhelmstr. 25-30, Berlin, 13593, Germany The joint research project “Geopotential of the German North Sea” (GPDN) determine and supply geological basic information with regard to a better understanding of the deeper underground and its potential usage. Based on available maps from Baldschuhn et al. (2001) together with the first mapping of the northwest part of the German North Sea, a geological 3D model is constructed within the project that serves as framework for a 3D facies model. The aim of our study will be the elaboration of a 3D facies model to gain a better understandig of the spatial distribution of reservoir and seal rocks in different stratigraphic levels in the deeper subsurface. As a first step, we selected a suite of boreholes from the eastern part of the German North Sea that comprise Permian and Mesozoic formations to construct 2D profiles through the study area. For stratigraphic correlation we use markers that include both, information from well descriptions and seismic interpretation. Furthermore, we show the reconstruction and interpretation of the lithology based on cuttings and core descriptions as well as other available data like geophysical logs (GR and Sonic). The selected cross section runs from NE to SW from the Westschleswig Block to the border of the Netherlands. The basis of the Upper Rotliegend formation as the deepest existing stratigraphic marker in the wells is located at depths between 4000 and 5200 m. Jurassic sediments are missing throughout the section. The greatest variation of thickness can be observed in the Upper Rotliegend, Zechstein and in the Keuper deposits. Based on the situation in the centre of the Southern Permian Basin the facies differs considerably in time and only in minor part in the stratigraphic extent. Baldschuhn, R., Binot, F., Fleig, S. & Kockel, F. (2001): Tectonic Atlas of Northwest Germany and the German North Sea Sector. – Geol. Jb., A 153, Hannover. 9-11 BTH 29 Thöle, Hauke LATE CENOZOIC DELTA DEPOSITION IN THE GERMAN NORTH SEA THÖLE, Hauke1 , REINHARDT, Lutz1 , and KUHLMANN, Gesa2 , (1) Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, Hannover, 30655, Germany, Hauke.Thoele@bgr.de, (2) Federal Institute for Geosciences and Natural Resources, Branch office Berlin, Wilhelmstr. 25-30, Berlin, 13593, Germany Within the framework of the GPDN project (www.geopotenzial-nordsee) we study the sedimentary evolution in the southern North Sea Basin during the Neogene. The Neogene sedimentary succession of the southern North Sea Basin is dominated by a large fluvio-deltaic system, also known as the “Eridanos delta system”. It drained the Fennoscandian and Baltic Shield through the present Baltic Sea and delivered huge amounts of sediments into the basin. The dimensions of the paleo-drainage area and the thickness of the deltaic deposits as A14 FRAGILE EARTH: Geological Processes from Global to Local Scales seen in the present North Sea are comparable to those of the largest recent delta systems in the world (Overeem et al., 2001). An almost complete coverage of the offshore parts of the delta with high-quality 2D and 3D seismic data in the German North Sea, together with new biostratigraphic datings of well samples allow studying the delta system in unprecedented detail filling the gap between former Dutch and Danish studies. The combined data sets collected within the framework of the “GPDN” project and a previous BGR North Sea project enables us to image the detailed architecture of the prograding delta system, and to identify areas of main subsidence during the Neogene. Initial studies of the delta system have provided detail insights about the location of delta complexes, collapse of the delta slope, migration of depocentres through time and age of delta sequences. Overeem, I., et al. (2001): The Late Cenozoic Eridanos delta system in the Southern North Sea Basin: a climate signal in sediment supply?, Basin Research, 13(3), 293-312. 9-12 BTH 30 Weber, Karolin FROM FACIES VARIATIONS TO PETROPHYSICAL PROPERTIES: EXAMPLES FROM THE LOWER TRIASSIC OF THE NORTH-EASTERN GERMAN BASIN WEBER, Karolin, GAST, Sascha, and KUHLMANN, Gesa, Federal Institute for Geosciences and Natural Resources, Branch office Berlin, Wilhelmstr. 25-30, Berlin, 13593, Germany, karolin.weber@bgr.de The Buntsandstein is stratigraphically the lowermost part of the tripartite German Triassic which is characterised by multiple successions of reddish to brownish sandstones and claystones. In the north-eastern German Basin these sediments are typically deposited by fluvial to brackish environmental systems. This work describes lower Triassic sediments with the help of geophysical measurements from deep boreholes. From lithological descriptions clastic, fluvial to lacustrine and brackish deposits could be depicted showing grain size variations from clay to sand. By the construction of an E-W/N-S profile the variability of the sediment composition and their respective facies could be depicted together with the according petrophysical properties. The basis for our correlation is a borehole set taken from Hoth et al. (1993) together with their geophysical log measurements like gamma ray, acoustic and resistivity logs. With the use of these logs porosity and grain-size distribution have been calculated by petrophysical methods as used as standard method in hydrocarbon exploration. Finally, these results will be compared to regional maps that have been elaborated geothermal studies for the working area by Diener et al. (1989). First results of the well correlation show on the one hand that the porosity and the lithology vary with respect to the basin rim and basin centre but on the other hand as well from older to younger stratigraphic levels, i.e.Volpriehausen to Solling Formation. Additionally to the ‘manual’ well correlation we aim to correlate the logs based on a statistical method introduced by Olea (2002) to fit the log pattern of distinct lithological intervals between the boreholes. References Diener, I. et al. (1989), Geothermische Ressourcen im Nordteil der DDR. ZGI Berlin, 72p.. Hoth, K.; Rusbült, J.; Zagora, K.; Beer, H.; Hartmann, O. (1993), Die tiefen Bohrungen im Zetralabschnitt der Mitteleuropäischen Senke – Dokumentation für den Zeitabschnitt 1962 – 1990. Verlag der Gesellschaft für Geowissenschaften e. V. (i. G.). Berlin. Schriftenreihe für Geowissenschaften Olea, R. A. (2002), Correlator 5.2 – Computer program and user’s manual. Open File Report No. 2002-52, December 2002 9-13 BTH 31 Slama, Jiri TESTING THE ACCURACY OF DETRITAL ZIRCON AGE PROVENANCE – NATURAL AND EXPERIMENTAL APPROACH SLAMA, Jiri and KOSLER, Jan, Department of Earth Sciences, University of Bergen, Allegaten 41, Bergen, 5007, Norway, jiri.slama@geo.uib.no Several factors affecting the accuracy of detrital zircon age provenance studies have been investigated. We have aimed for quantifying the effects of individual factors that deviate the measured detrital age spectra from the real zircon age distribution in the sediment and in the sediment source. The effects of variable redistribution of zircons from source rocks into the stream have been studied in a natural catchment in Scotland that represent simple twocomponent source system. The factors affecting reproducibility of the age spectra of the sample were investigated on synthetic sediment prepared on purpose for this study using zircon-free quartz sand and known number of zircon grains of known age distribution. Our results show that the zircon fertility of the source rocks and physical parameters of zircon grains represent the most important factors affecting the distribution of zircon age populations in the stream sediments. It can account for a several-fold difference between the ratio of the rocks in the source area and abundance of zircon in the sediment. Additional age biases are introduced during sample preparation and data processing. The sample preparation and grain picking result in loss of small grains and errorneous amplification of the age component represented by larger grains. This can, together with the preference for larger grains during handpicking, cause several-fold difference compared to the real age distribution in the sediment sample. These factors are more important for the reproducibility of zircon age spectra than is the number of zircon grains analyzed per sample. Even the most abundant age population in the sample may deviate by tens of percent from its real content in the sediment after hundred or more analyses have been done. It is therefore difficult to relate the peak intensity in the age spectra to the sediment quantity contributed from different sources. The analytical limits of the dating techniques must always be considered when evaluating potential overlap of zircon populations that are closely spaced in time. Although the visualization of U-Pb data in probability density plots is commonly used for comparison between samples, the detrital zircon age spectra must always be interpreted relative to the volume of individual age populations, not to the intensities of the age peaks.
SESSION NO. 10, 08:30 Monday, 5 September 2011 T3E. Transient Deformation in the Lithosphere at Conditions Changing over Short Periods of Time (Posters) Ludwig-Maximilians-Universität München, Poster Hall P1 (E110, Senatsraum, 1st floor) 10-1 BTH 15 Dokukina, Ksenia HIGH-VELOCITY DEFORMATION AND SYNCHRONOUS MAFIC MELT INTRUSION DOKUKINA, Ksenia, Russian Academy of Sciences, Geological Institute of RAS, Pyzhevsky Lane 7, Moscow 119017 Russia, dokukina@mail.ru The Tastau volcanoplutonic complex of the Chara transpressional belt, Eastern Kazakhstan, contains the mafic microintrusions (1-70 cm) in the form of strings of globules and other bodies that resemble stretched and boudinaged dykes in low-grade sedimentary rock. All mafic bodies have got chilled margins and are located exclusively in the linear zone of tectonic brecciation of metagreywacke host rock. In outcrop, the mafic bodies thus often look like beads that connected by a bead string. These structures are result of primary magma emplacement rather than postconsolidation stretching. The formation of these mafic microintrusions was controlled by compressive shear deformations. Progressive stretching during a high-speed decompression deformation of metasedimentary rock was accompanied by intrusion of mafic melt. Magma fragmentation due to the significant decrease in matrix viscosity took place during high-velocity shearing and cataclastic flow. The synkinematic model of fragmentation and mingling between magma and deforming rock on the hypabyssal level of crust is offered. In the Tastau area the melt fragmentation structures and tectonites are evidence of dramatic changes in the tectonic regime from compression to extension and again to compression. Two main factors determined such inversion: (1) regional tectonics and (2) magmatic fluid pressure, which could operate simultaneously. The model assumes a relative long preservation of regional compressive conditions. Impenetrable areas impeded the magmatic melt motion and produced a fluid overpressure. At excess of limiting pressure a deviator stress relaxation and a hydrofracturing were realized which appeared in the tectonic crushing. The disintegration of host rock was accompanied by a mafic melt filling of fractures. Softening of the crushed matrix, a loss of mechanical solidity and viscosity decrease of matrix (up to acquisition of quasi-liquid property) took place in ruptured zones with the participation of melt fluid. Consequently stress relaxation was realized with cataclastic flow and melt injection in northwest linear local fault zones in the compression conditions. 10-2 BTH 16 Wassmann, Sara THE RECORD OF STRESS CYCLES IN FRONT OF A PROPAGATING THRUST FAULT NÜCHTER, Jens-Alexander, WASSMANN, Sara, and STÖCKHERT, Bernhard, Ruhr- Universität Bochum, Geology, Mineralogy and Geophysics, Universitätsstraße 150, Bochum, 44801, Germany, sara.wassmann@rub.de Juvenile faults grow by propagation. If a fault grows during repeated earthquakes, the crust facing the fault front is subject to consecutive stress cycles as the fault front approaches the site of observation. When the front of a thrust fault has passed the site of observation, the hanging wall becomes decoupled from its former substratum, and can be transported as a nappe. If so, the pre-decoupling stress history may be preserved in the rocks at the nappe base. The base of the Preveli nappe, Crete, is formed by a 30 m thick cataclasite. Above the cataclasite, the metamorphic rocks in the interior of the nappe show structures, indicating (1) deformation of quartz by dislocation creep at high differential stress, (2) brittle failure and vein formation controlled by ductile creep of the host rock, and (3) deformation of the vein quartz in the regime of low-temperature plasticity. Overprinting relations show that these features formed in a systematic sequence. All microstructures are also observed inside the rotated clasts in the cataclasite. The cataclasite is crosscut by undeformed pseudotachylite veins. For our site of observation we propose: (1) The stress cycles recorded in the quartz microfabrics are related to a sequence of earthquakes, during which the fault front propagated closer to the site of observation. (2) The cataclasite formed immediately after passage of the fault front from an intensively fractured wake left behind by the process zone. (3) Formation of pseudotachylite veins indicates injection of frictional melts after cataclasite formation. (4) The undeformed preservation of these pseudotachylite veins indicates localization of any subsequent deformation into the underlying weak thrust plane. Notably, nappe transport after pseudotachylite injection did not leave a discernible imprint at the site of observation. (5) All this happened in the middle crust, as indicated by the composition of phengites grown in the pseudotachylite matrix during devitrification. We propose that cataclasite and pseudotachylite formation mark the end of a history of coseismic loading and postseimic stress relaxation at the site of observation. Such type of record may be systematically found at the base of thrust sheets decoupled in the middle crust. 10-3 BTH 17 Kruhl, Jörn H. QUARTZ MICROFABRICS AS INDICATORS OF HIGH- TO LOW-TEMPERATURE SHEARING UNDER VARIABLE RATES OF DEFORMATION KRUHL, Jörn H. and STÄB, Christian, Tectonics and Material Fabrics Section, Technical University of Munich, Arcisstr. 21, Munich, 80333, Germany, kruhl@tum.de We present an investigation on microfabrics of quartz-porphyric veins from the Western Alps where various parameters of deformation and metamorphism can be determined and information about high strain-rate variations can be inferred. (1) Cooling rates of the wall rocks are known. (2) Based on deformation of euhedral magmatic quartz and on biotite orientation in the ground mass, strain can be determined. (3) The initial vein thickness can be calculated, ranging from ~ 1 to > 50 m. (4) Vein composition leads to the temperature of the magma, which – together with vein thickness and wall-rock temperature – allows to model cooling rates of the veins. Since the magma was injected at T-peak of regional metamorphism, the quartz-porphyric veins cooled rapidly down to T ~ 450-600°C and then experienced slow cooling of regional metamorphism. A variety of high-T deformation fabrics developed in quartz, such as chessboard subgrain patterns, large recrystallized grains that partly grew up to the size of the magmatic host grain, and coarse grain-boundary sutures. Medium- to low-T fabrics include subgrains, dynamically recrystallized grains and small-scale grain-boundary suturing. Brittle or semi-brittle deformation structures developed within this sequence of ductile structures and indicate variation of deformation rate: (1) fractures, along which arrays of recrystallized grains are formed; (2) kink-bands that are changed to arrays of subgrains and, by grain-boundary migration recrystallization, to arrays of dynamically recrystallized grains; (3) kink-band boundaries that are transformed to deeply serrated high-angle grain boundaries. SESSION NO. 10 In general, the detailed knowledge about various properties of the veins and their wall-rocks as well as the conditions of regional metamorphism and deformation allows far-reaching analyses of the interaction between rock fabrics and variable deformation rates. 10-4 BTH 18 Druiventak, Anthony G. KICK AND COOK OF PERIDOTITE: COSEISMIC LOADING AND POSTSEISMIC RELAXATION VERSUS STEADY-STATE CREEP DRUIVENTAK, Anthony G. 1 , TREPMANN, Claudia A. 2 , MATYSIAK, Agnes K. 1 , and RENNER, Jörg1 , (1) Institute of Geology, Mineralogy and Geophysics, Ruhr-Universität Bochum, Universitätstraße 150, Bochum, 44801, Germany, anthony.druiventak@rub.de, (2) Ludwig-Maximilians-Universität München, München, Germany Experiments comprising a sequence of deformation at moderate temperature (600°C) and annealing at higher temperature (700 to 1000°C) were performed on samples of natural peridotite to simulate the natural stress history in the suboceanic upper mantle just below the seismogenic zone. Analyses of the olivine microfabric development revealed that deformation of olivine takes place by microcracking and dislocation glide in the low-temperature plasticity field. During annealing, recovery and recrystallization in olivine are driven by the reduction of strain and grain boundary energy. High strain zones generated during deformation are replaced by olivine subgrains and recrystallized olivine grains at low and high annealing temperatures, respectively. Furthermore, the microstructures after annealing at high temperature (1000°C) are characterized by large olivine clasts surrounded by small recrystallized grains, which resemble the microstructures found in naturally deformed peridotites in the Western Alps. Such microstructures, commonly described as core-and-mantle structures, have previously been addressed as evidence for incipient dynamic recrystallization during steady-state dislocation creep. The average size of the recrystallized grains is then used in conjunction with experimentally constrained paleo-piezometer relations to infer constraints on paleo-stress. Our deformation and annealing experiments suggest an alternative scenario of initial high stress deformation followed by recrystallization at rapidly decaying stresses (or hydrostatic stress) - considered to mimique the sequence of mechanical states during an earthquake – for the development of such microstructures, so that paleo-piezometers do not apply to the natural stress history. 10-5 BTH 19 Dokukina, Ksenia MEZOARCHEAN METAPSEUDOTACHYLITE AS EVIDENCES OF SEISMIC DEFORMATION OF THE EARLY PRECAMBRIAN CONTINENTAL CRUST (BELOMORIAN ECLOGITE PROVINCE) DOKUKINA, Ksenia1 , BAYANOVA, Tamara B. 2 , KONILOV, Alexander1 , and VAN, K.V. 3 , (1) Russian Academy of Sciences, Geological Institute of RAS, Pyzhevsky Lane 7, Moscow, 119017, Russia, dokukina@mail.ru, (2) Russian Academy of Sciences, Geological Institute KSC RAS, Fersman str. 14, Apatity, Murmansk rgn, 184209, Russia, (3) Russian Academy of Sciences, Institute of Experimental Mineralogy, Chernogolovka, Moscow region, 142432, Russia We studied metapseudotachylite acid veins in central domain of Izbnaya Luda island (Mezo- Neorchean Belomorian eclogite province), VGS-84: N 65º54’, E 34º45’. It is underlain by felsic gneiss, in which occur bodies of eclogite, amphibolite, garnet-clinopyroxene amphibolite, metaperidotite, metapyroxenite, and microcline granite. The area studied may be divided into western, central and eastern domains. Central domain rocks have a prevailing northwesterly and westerly foliation trends. Gneiss foliation is cut by minor faults (several centimeters to several meters displacement) of main northernly and secondary westerly directions. Movement along faults produced tectonic breccia. The layered quartzofeldspathic gneiss contains fragments, 10 cm to 5 m in size, of garnet (± clinopyroxene) amphibolite, eclogite, tonalite and pink K-rich granite. The granite and tonalite fragments are angular or are elongated parallel to the foliation. A fault networks are irregularly distributed in area. Locally, early fold relicts are preserved within the network of faults. Tectonic breccia contains thin (from few millimeters to few centimeters) metapseudotachylite veins are presented fine-grained aplite-like rocks and they cross-cut all rocks of breccia. Relatively large-scale aplite veins contain small fragments of plagiogneiss and K-rich granite. Sometimes thin aplite veins form a thick net that envelops of gneiss and granite fragments. Metapseudotachylite represents garnet – biotite – plagioclase - potassium feldspar – quartz ± clinopyroxene ± hornblende metamorphized rock. Metapseudotachylite composition (SiO2 68.7-70.4, TiO 0.4, Al O 14.9-15.4, Fe O 3.5-3.8, MnO 0-0.1, MgO 1.2-1.4, CaO 3.0-3.4, 2 2 3 2 3 Na O 3.7-3.8, K O 1.9, P O 0.1-0.2) corresponds to average composition of the rocks of 2 2 2 5 tectonic breccia. Eight samples of metapseudotachylite were dated by bulk rock Sm/Nd method and yielded T model ages from 2787 to 3148 Ma. Thus metapseudotachylite veins are an DM important evidence of a high-velocity seismic deformation of the Mezoarchean continental crust. Errochrone dependence gave age about 1.53 Ga, which obviously answer alteration of Sm/Nd isotopic system at the amphibolite-grade overprinting in the Svecofennian Orogeny. 10-6 BTH 20 Matysiak, Agnes K. CYCLIC NON-STEADY STATE DEFORMATION RECORDED BY PERIDOTITES OF THE FINERO COMPLEX (IVREA ZONE, WESTERN ALPS) MATYSIAK, Agnes K. 1 , STÖCKHERT, Bernhard1 , and TREPMANN, Claudia2 , (1) Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Universitätsstr. 150, Bochum, 44801, Germany, agnes.matysiak@rub.de, (2) Ludwig-Maximilians-Universität, München, Germany The microfabrics of deformed peridotites of the Finero complex (Ivrea Zone, western European Alps) are investigated by optical and electron microscopic techniques (SEM/EBSD, TEM). The rocks are lherzolites and contain minor amounts of amphibole and/or phlogopite. They have undergone multiple stages of deformation and metamorphism. The SPO of large elongate olivine grains (long axis up to 15 mm) defines the foliation of the peridotite. These grains are inhomogeneously deformed, containing abundant kink bands and deformation bands sub parallel to (100). Kink bands are characterized by discrete boundaries with a misorientation of up to 35°. Kink band boundaries and grain boundaries are sutured indicating strain-induced grain boundary migration after inhomogeneous deformation. Deformation bands are defined by sub parallel, more or less straight but diffuse low angle grain boundaries. Their orientation sub parallel (100) indicates the activation of a glide system with [100] as glide direction, which is reported to be characteristic for high temperature deformation. Locally, kink band boundaries cut deformation bands at a low angle; otherwise both features are sub parallel. In zones of localized deformation, olivine microstructures reveal at least two stages of recrystallization. An earlier generation of recrystallized grains, 0.1-0.3 mm in diameter, shows a foam structure, which implies annealing at low differential stress. A later generation of recrystallized grains, less than about 0.05 mm in diameter, is confined to shear zones about parallel to the foliation. These grains show an irregular grain shape and a weak CPO, indicating deformation in the dislocation creep regime. These shear zones (mm-cm wide) appear to have been repeatedly reactivated. The latest deformation stage is represented by ultrafine grained, cataclastic and metasomatized domains containing serpentine, talc and dolomite. The microstructures in the Finero peridotites indicate episodic, markedly non-steady state deformation, recording several cycles with initially high differential stress and subsequent stress relaxation. The stress cycles which occurred under distinct conditions are attributed to Munich, Germany A15 Monday
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Page 132 and 133: SESSION NO. 27 Our seismic data pro
Page 134 and 135: SESSION NO. 28 has been sheared dur
Page 136 and 137: SESSION NO. 31 the case of minerals
Page 138 and 139: SESSION NO. 31 well-sorted fluvial
Page 140 and 141: SESSION NO. 33 Whether the higher C
Page 142 and 143: SESSION NO. 34 size, while mafic St
Page 144 and 145: SESSION NO. 36 along the Emperor ch
Page 146 and 147: SESSION NO. 36 36-14 16:50 Meier, T
Page 148 and 149: SESSION NO. 37 37-10 15:10 Mulch, A
Page 150 and 151: SESSION NO. 38 the Rotliegend to th
Page 152 and 153: SESSION NO. 39 39-13 15:30 Zellmer,
Page 154 and 155: SESSION NO. 41 Taking into account
Page 156 and 157:
SESSION NO. 42 42-10 BTH 19 Douille
Page 158 and 159:
SESSION NO. 43 We found the analog
Page 160 and 161:
SESSION NO. 45 SESSION NO. 45, 14:0
Page 163 and 164:
A Abdel Moneim, Ahmed 40-6 Abe, Ste
Page 165 and 166:
Mori, Jim 35-2* Morton, Andrew C. 3
Page 167 and 168:
Notes:
Page 169 and 170:
Notes:
Page 171 and 172:
Mud-Logging Service Drilling Monito
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