Die geodynamische Entwicklung der Thiersee- und der Karwendelmulde (Nördliche Kalkalpen)

Zusammenfassung Die Thiersee- und die Karwendelmulde in den Nördlichen Kalkalpen sind als zwei getrennte, E-W-verlaufende Synklinen entwickelt. Ihre Länge zwischen Kufstein und Mittenwald beträgt über 70 km.Systematische geologische Aufnahmen — Kartierung, Stratigraphie, Sedimentologie und Gefügekunde — ergaben, daß die Thierseemuide im Raum von Achenkirch nicht — wie früher vermutet wurde — in die Karwendelmulde umbiegt. Die Auswertung von mehr als 45 000 Gefügemessungen mit Hilfe eines EDV-Programms bewies vielmehr, daß Thierseemuide und Karwendelmulde zwei parallele, unabhängige Strukturen sind, die durch die komplizierte tektonische Zone von Achenkirch getrennt werden.Die paläogeographische Entwicklung und der Ablauf der Bewegungen werden im Überblick skizziert.

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Systematic geological survey showed that the Thiersee and Karwendel synclines in the Northern Calcareous Alps are two parallel structures, separated by a slightly folded intersection. The synclines do not turn into each other, as was presumed by earlier workers.The tectonic situation in the area of Achenkirch was cleared by evaluation of more than 45,000 field texture data by a computer program. Mapping as well as stratigraphical and sedimentological analysis supports the tectonic model. The paleogeographic development and tectonic history are briefly described.

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Résumé Les dépressions du «Thiersee» et du «Karwendel», dans les Alpes calcaires du Nord, sont deux synclinaux indépendants de direction Est-Ouest. Elles font 70 km de long entre Kufstein et Mittenwald.Des relevés géologiques systématiques — levés géologiques, stratigraphie, sédimentologie et structurologie — démontrèrent que, dans la région d'Achenkirch, la dépression du «Thiersee» ne contourne pas la dépression du «Karwendel» (comme on l'a longtemps supposé!). L'exploitation par ordinateur de plus de 45.000 mesures structurales révéla au contraire, que ces dépressions sont deux structures parallèles et indépendantes, séparées par la zone tectonique complexe d'Achenkirch.Le développement paléogéographique et le déroulement des mouvements font l'objet d'une vue d'ensemble.

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The application of computer-assisted photogrammetric methods in the structural analysis of part of the North Greenland Fold Belt

The development of computer support in photogrammetric measurements has facilitated quick calculations of structural geological elements such as strike and dip, fold axes and axial planes. Computer-assisted photogrammetric methods have been applied in a structural analysis of 3000 km² in central Peary Land, North Greenland. Detailed studies have been carried out in an area covered by a single stereo model representing part of the southernmost margin of the North Greenland Fold Belt. On the basis of the aerial photos, a map with both lithological boundaries and structural measurements may be drawn. In little known areas with complex structural relationships field work is necessary to control the interpretation. In the present study refolded thrust fault structures were investigated. Preparatory photogrammetric studies allow the limited time available for field work to be effectively utilised, and accurate geological maps to be produced relatively quickly.     

A shale buchite xenolith with Al-armalcolite and native iron in a lava from Asuk,Disko, central West Greenland

A native iron bearing buchite xenolith enclosed in basalt in a native iron bearing lava from Disko is similar in chemistry, apart from volatile components, to unheated Mesozoic to early Tertiary carbonaceous shale sediments from West Greenland, believed to have been the major contaminant and reducing agent causing the formation of the native iron in the volcanic rocks on Disko. The shale buchite has preserved original sedimentary lamination and experienced only a comparatively short-lived heating which allowed only short-range equilibration. The xenolith contains native iron and graphite, while the immediately enclosing basalt does not, and demonstrates the indigenous reducing properties of the shales when heated to high (1,150–1,200 ° C) temperatures at low pressures. Sedimentary clastic iron titanium oxide grains have reacted with the immediately surrounding matrix and completely recrystallized to aggregates of rutile and Al-armalcolite with up to 24 mol% Al₂TiO₅. The Al-armalcolites contain 5 to 11 mol% of the anosovite (Ti₃O₅) component. They show a considerable variation in iron-magnesium ratio due to small-scale variations in bulk chemistry to varying f _O2 and to the effects of progressive melting of the sediment. Glassy veins in the buchite, formed along original fractures in the sediment, contain an assemblage of cordierite, low Ca-pyroxene, plagioclase, ilmenite, ferropseudobrookite-rich armalcolite, iron metal, troilite and acid glass, and crystallized under higher oxygen fugacities than the buchite interior, probably due to influx from the less reduced enclosing basalt magma.     

Acidic compounds in biodegraded petroleum

Twelve oil samples have been characterised by titration, FT-IR and chromatographic analysis to determine the differences between the organic acid composition of biodegraded and non-biodegraded oils. The biodegraded oils have higher total acid and total base contents, both by titration and extraction. The molecular weight ranges of the extracted acids are lowest in the biodegraded oils, and the equivalent weight calculations indicate a dominance of multi-functional molecules. Gel permeation chromatography gives a molecular weight range with most of the molecules between 300 and 500 g/mol. FT-IR shows that the extracted acids from biodegraded oils are more carboxylic and aliphatic while the non-degraded oils are more phenolic. Molecular analysis of the derivatised extracts give UCM envelopes for biodegraded oils, and no molecular identification. The results indicate that the acidic constituents in biodegraded oils are a product of the biodegradation, as the composition is very different from the non-biodegraded oils.     

震后地形变与孔隙压力瞬态变化的相互关系

大震改变地壳的应力,从而触发地震及其余震。一系列随时间变化的过程,包括余滑、孔隙流体的流动、下地壳和上地幔粘性的张驰、断层附近应力和孔隙压力调整以及地震的触发进程。然而,尽管进行过多次尝试,但通过直接场地的观测,很难将这些过程区分开来。这里我们采用一种星载雷达干涉图和冰岛南部地震带两个6.5级地震地热井水位变化过程结合的测量法。干涉图记录到的形变既不能用余滑也不能用粘-弹性张驰来解释,但它与地震发生后最初两个月孔隙弹性物质的回跳一致,这可以用地震引起水位变化的快速恢复(1—2个月)来证实,相反余震序列的持续时间达到3.5年,这表明余震的持续时间并不是由孔隙流体的流动控制的,但是,因为表面应变是由地壳浅部孔隙压力的变化控制的,因此,我们不能排除在余震发生深度存在较长时间的孔隙压力瞬态变化。余震的持续时间与随速度和状态变化的摩擦定律控制的地震活动变化速率模型是一致的。     

Testing theories of the vertical stratification of the ACC against observations

Recent theories of the Antarctic Circumpolar Current (ACC) suggest that its lateral and vertical stratification is controlled by its baroclinic instability: eddies in the ACC not only feed-off the available potential energy stored in sloping isopycnals but play a central role is setting up that stratification. Simple theory makes predictions about how the depth of the thermocline in the ACC depends on the surface winds, the air–sea buoyancy flux and transfer by baroclinic eddies. By examining gridded hydrographic data, here we test some of these predictions against observations. We show that, to a remarkable degree, the buoyancy field in the ACC decays exponentially with depth beneath the mixed layer. The e-folding depth increases equatorward, from less than 500 m on the poleward flank of the ACC to greater then 1000 m on its equatorial flank, in a manner that is broadly consistent with the theory.     

Hydrological modelling in the anthroposphere: predicting local runoff in a heavily modified high-alpine catchment

Hydrological models within inflow forecasting systems for high-alpine hydropower reservoirs can provide valuable information as part of a decision support system for the improvement of hydropower production or flood retention. The information, especially concerning runoff, is however rarely available for the calibration of the hydrological models used. Therefore, a method is presented to derive local runoff from secondary information for the calibration of the model parameters of the rainfallrunoff model COSERO. Changes in water levels in reservoirs, reservoir outflows, discharge measurements at water intakes and in transport lines are thereby used to derive the local, “natural” flow for a given sub-catchment. The proposed method is applied within a research study for the ÖBB Infrastructure Railsystem division in the Stubache catchment in the central Austrian Alps. Here, the ÖBB operates the hydropower scheme “Kraftwerksgruppe Stubachtal”, which consists of 7 reservoirs and 4 hydropower stations. The hydrological model has been set up considering this human influences and the high natural heterogeneity in topography and land cover, including glaciers. Overall, the hydrological model performs mostly well for the catchment with highest NSE values of 0.78 for the calibration and 0.79 for the validation period, also considering the use of homogeneous parameter fields and the uncertainty of the derived local discharge values. The derived runoff data proved to be useful information for the model calibration. Further analysis, examining the water balance and its components as well as snow cover, showed satisfactory simulation results. In conclusion, a unique runoff dataset for a small scale high-alpine catchment has been created to establish a hydrological flow prediction model which in a further step can be used for improved and sustainable hydropower management.     

Data-moderate assessments of Cape monkfish Lophius vomerinus and west coast sole Austroglossus microlepis in Namibian waters

There is global interest in providing scientific advice on optimal harvesting of all commercially exploited fish stocks. Nevertheless, many commercially important stocks lack analytical assessments. Therefore, we evaluate a data-moderate stock assessment method: the stochastic surplus production model in continuous time (SPiCT). The method was applied to two Namibian stocks: (i) the data-rich Cape monkfish Lophius vomerinus, where results are compared to a new data-rich assessment using a state–space assessment model (SAM); and (ii) the data-moderate west coast sole Austroglossus microlepis, which is an important bycatch species in the Cape monkfish fishery, but currently unassessed. The information available to the data-moderate assessment is total commercial catch, commercial catch per unit effort (CPUE), and survey CPUE. SPiCT and SAM gave largely consistent estimates of relative fishing mortality (F/F_MSY) and relative exploitable biomass (B/B_MSY) for the Cape monkfish stock, although with some discrepancies. Differences in the biomass estimates between the two assessments suggest that further investigation is required to understand the cause, and that some caution is necessary when considering the biomass of the stock. SPiCT shows that the west coast sole may be overexploited, although the confidence bounds were too wide for a firm conclusion. Similarity in the estimates of F/F_MSY for Cape monkfish in recent years, using SPiCT relative to SAM, likewise indicates the suitability of SPiCT for managing west coast sole.