Austrian Journal of Earth Sciences最新文献

{"title":"Runout-modelling of shallow landslides in Carinthia (Austria)","authors":"W. Poltnig, R. Bäk, W. Berg, Teja Keršmanc","doi":"10.17738/AJES.2016.0004","DOIUrl":"https://doi.org/10.17738/AJES.2016.0004","url":null,"abstract":"Shallow translational landslides and earth-flows (mixing process between landslide and flow process) are the most common and most problematic types of landslides relating to the weathering of the bedrock and unconsolidated slope deposits in Carinthia. These types of landslides can reach high speeds and travel long distances. Usually only the uppermost meters of loose sediments of the slope are affected and heavy rain events after a pre-saturation of the soil are typically triggers for such landslides. As part of a research project in Carinthia an Add-In for ArcGIS 10x was developed. This Add-In calculates the runout for these common types of mass movements on the basis of available data on a regional scale. The runout modelling assumes that the soil is presaturated and additional precipitation in susceptible area triggers the landslides. The calculation of the runout distances is performed using a specially programmed ArcGIS Add-In. The calculation requires the following information: Initiation cells of high susceptibility to landslide processes (slope failure initiation zones); digital elevation model (DEM); geology; surface roughness (generated from the landuse map); and curvature (this affects the drainage of the mass movement). The runout modelling takes into account the variability of the „trigger“ and mobility as a function of water saturation in shallow landslides. The calibration of the parameters is based on simulations of initiation cells with known events so that it can be assumed that the simulation results match the conditions corresponding to events observed in the region. The model allows easy and fast recalculation for parts of the area if needed (new findings due to events). Von den unterschiedlichen Rutschungstypen sind die Translationsrutschungen und Hangmuren, die die Verwitterungsund Lockersedimentüberlagerung betreffen, die häufigsten und problematischten in Kärnten. Meist sind nur die obersten Meter der Lockersedimente eines Hanges betroffen und als Auslöser für derartige Rutschungen ist meist ein Starkregenereignis nach einer Vorsättigung des Bodens mit Wasser verantwortlich. Diese Rutschungstypen können große Geschwindigkeiten und große Reichweiten erreichen. Im Rahmen eines Forschungsprojektes des Landes Kärnten wurde ein Add-In für ArcGIS entwickelt, welches für diesen häufig auftretenden Typ von Massenbewegungen den Runout auf der Basis vorhandener Daten im regionalen Maßstab berechnen soll. Die Runoutmodellierung geht davon aus, dass der Boden mit Wasser vorgesättigt ist und ein zusätzlicher Niederschlag Rutschungen in den Startbereichen hoher Suszeptibilität auslöst. Die Berechnung der Runout-Reichweiten erfolgt mittels eines eigens programmierten ArcGIS Add-Ins. Zur Modellierung der Wirkungsräume werden folgende Datensätze verwendet: Suszeptibilitätsflächen (Startzellen), digitales Höhen modell, Geologie, Oberflächenrauigkeit (generiert aus der Landnutzung) und Curvature (Parameter für die Wölbung, beeinflusst u.a. ","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbially-driven formation of Cenozoic siderite and calcite concretions from eastern Austria","authors":"Lydia M. F. Baumann, D. Birgel, M. Wagreich, J. Peckmann","doi":"10.17738/AJES.2016.0016","DOIUrl":"https://doi.org/10.17738/AJES.2016.0016","url":null,"abstract":"Carbonate concretions from two distinct settings have been studied for their petrography, carbon and oxygen stable isotope patterns, and lipid biomarker inventories. Siderite concretions are enclosed in a Paleocene-Eocene deep-marine succession with sandy to silty turbidites and marl layers from the Gosau Basin of Gams in northern Styria. Septarian calcite concretions of the southern Vienna Basin from the sandpit of Steinbrunn (Burgenland) are embedded in Upper Miocene brackish sediments, represented by calcareous sands, silts, and clays. Neither for the siderite, nor for the calcite concretions a petrographic, mineralogical, or stable isotope trend from the center to the margin of the concretions was observed, implying that the concretions grew pervasively. The δC values of the Gams siderite concretions (-11.1 to -7.5‰) point to microbial respiration of organic carbon and the δO values (-3.5 to +2.2‰) are in accordance with a marine depositional environment. The low δC values (-6.8 to -4.2‰) of the Steinbrunn calcite concretions most likely reflect a combination of bacterial organic matter oxidation and input of marine biodetrital carbonate. The corresponding δO values (-8.8 to -7.9‰) agree with carbonate precipitation in a meteoric environment or fractionation in the course of bacterial sulfate reduction. Lipid biomarkers have been extracted before and after decalcification of the concretions in order to assess pristine signatures and to exclude secondary contamination. The siderite concretions did not yield indigenous biomarkers due to their high thermal maturity. The calcite concretions comprise abundant plant wax-derived long-chain n-alkanes, reflecting high terrestrial input. Bacterial-derived, terminally-branched fatty acids and hopanoids were found, but with overall low contents. The presence of framboidal pyrite, the moderately low δC values, and the biomarker inventory indicate that bacterial sulfate reduction contributed to the formation of the calcite concretions in a brackish environment. The low δC values of the siderite concretions, on the other hand, are best explained by bacterial iron reduction, since sulfate reduction and resultant hydrogen sulfide production would have inhibited siderite precipitation. This study documents a new example for an exception from the common pattern that siderite concretions preferentially precipitate in freshwater environments. The Gams siderite concretions formed within marine sediments, whereas the Steinbrunn calcite concretions formed in freshwater to brackish sediments. Karbonatkonkretionen aus verschiedenen Ablagerungsräumen wurden im Hinblick auf ihre Petrografie, stabile Kohlenstoffund Sauerstoffisotope und Lipidbiomarkerinhalt untersucht. Sideritkonkretionen entstammen paleozän-eozänen, tiefmarinen, sandigen bis schluffigen Turbiditen und Mergellagen des Gosaubeckens von Gams in der nördlichen Steiermark. Septarische Kalzitkonkretionen des südlichen Wiener Beckens aus der Sandgrube von Stei","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"24 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"About faunal life in Austrian aquifers - historical background and current developments","authors":"S. Hilberg, U. Eisendle-Flöckner","doi":"10.17738/AJES.2016.0009","DOIUrl":"https://doi.org/10.17738/AJES.2016.0009","url":null,"abstract":"In Austria all general types of aquifers (porous, karstic and fractured) are present and are subject of hydraulic and hydrochemical in- vestigations. However, in hydrogeological research it is a still widely neglected fact that groundwater flow is not only a flux of water, chemicals and heat within lithological units but that groundwater bodies may also act as habitats with very particular conditions for their inhabitants. In general groundwater inhabitants require three things: a place to live, oxygen and energy or food, respectively. Thus, the living conditions of groundwater animals are directly connected to hydrological and geomorphological conditions on a regional scale, and on a local scale, lithological and structural properties that control hydrogeological parameters such as porosity and hydraulic conductivity, recharge mechanisms and flow dynamics. In this paper we view Austrian hydrogeology from the perspective of groundwater fauna in order to elucidate the connection between the hydrogeological conditions and biological patterns. A brief review of groundwater biology research in general and spe- cifically in Austria, revealed that crustaceans are basically in the focus of groundwater research while other common groundwater dwellers, such as free-living nematodes, are less studied similarly. Porous aquifers are comparably well investigated by groundwater biologists, while fractured aquifers have rarely been considered as habitats to date. Due to the complex hydrogeological situation in Austria, with a greater portion of fractured and karstic aquifers, a systematic biological survey considering hydrogeological aspects may lead to a pronounced progress for the both disciplines, hydrogeology and groundwater biology. For hydrogeological purposes, the studies may provide the basis for using groundwater species (similar to the established method of using stable isotopes) as natural tracers in future studies. From the biological perspective, progress in the understanding of complex habitat-biota relations is expected to result from the investigation of hitherto unknown habitats. In addition, such a survey would not only be an important contribution to biodiversity and biogeography in Austria, it would also pro- mote groundwater research in a broader context, such as the need to protect groundwater as a valuable service providing system (e.g. water quality). Preliminary results from six test sites distributed to four different geological settings (Quaternary basin fill, Flysch-Zone, Northern Calcareous Alps and the Central Crystalline Zone within the Alps) show evidence for a link between the hydrogeological conditions and the present biological assemblages. However, a systematic survey is still required to understand which environmental factors mainly govern live in Austrian aquifers.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The drowning of ancient Limyra (Southwestern Turkey) by rising groundwater during Late Antiquity to Byzantine times","authors":"G. Rantitsch, W. Prochaska, M. Seyer, H. Lotz, C. Kurtze","doi":"10.17738/AJES.2016.0015","DOIUrl":"https://doi.org/10.17738/AJES.2016.0015","url":null,"abstract":"From the 6 th century BC to Byzantine times, the ancient city of Limyra was an important urban center of the Lycian territory at the southwestern coastal region of Asia Minor. Archaeological, geological, hydrochemical and surface elevation data, as well as 14 C age dating constrain a paleo-hydrogeological model, explaining the submergence of the city foundation walls below the groundwater table. In this model, tectonically induced subsidence of the acropolis (Tocak Dagi) initiated a debris flow into the area of the lower city. Both, natural and anthropogenic gravel accumulation resulted in the formation of a new aquifer pathway redirecting formerly bypassing karst water into the city center. Consequently, the inhabitants of Limyra had to fight against the rising ground water table at least since the 6 th to 10 th centuries AD. Die antike Stadt Limyra war vom 6. Jh. v.Chr. bis zu byzantinischer Zeit ein bedeutendes urbanes Zentrum in Lykien an der sud- westlichen Kuste von Kleinasien. Archaologische, geologische und hydrochemische Daten sowie ein Gelandemodell und ein 14 C Alter unterstutzen ein palao-hydrogeologisches Modell, welches das Absinken der Grundmauern der Stadt unter den Grundwasser- spiegel erklart. Das Modell beschreibt tektonisch induzierte Massenbewegungen vom Burgberg (Tocak Dagi) in die Unterstadt. Die naturliche und eine zusatzliche anthropogene Schuttanreicherung fuhrten zu einer Umleitung des ursprunglich vorbeifliesenden Grundwassers in das Stadtzentrum. Dies hatten die Bewohner von Limyra spatestens seit dem sechsten bis zehnten Jh. n. Chr. zu bewaltigen.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"64 1","pages":"203-210"},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depositional environment and provenance of the GrestenFormation (Dogger) on the southeastern slopes of the BohemianMassif (Czech Republic, subsurface data)","authors":"S. Nehyba, Vladimír Opletal","doi":"10.17738/AJES.2016.0020","DOIUrl":"https://doi.org/10.17738/AJES.2016.0020","url":null,"abstract":"The deposits of the Gresten Formation (Midle Jurassic) obtained from deep wells in the territory of southern Moravia (Czech Republic) have been newly examined with the aim to better describe their provenance and depositional environment. Deposition within a relatively broad flood plain with fluvial/distributive channels, crevasse channels, crevasses splays and coal-swaps have been recognised in the majority of well cores. Basinal/open marine deposits have been less common. The heavy mineral association is quite stable, with significant dominance of garnet and commonly also with high content of zircon. The mineralogical spectra of garnet types were broad with strong dominance of almandines. The rutiles were mostly derived from metapelites and additionally also from metamafic rocks and pegmatites. The results point to mixed sources from both intensively weathered crystalline rocks of the eastern margin of the Bohemian Massif (primary source) and the older sedimentary rocks - especially from the Moravo-Silesian Paleozoic deposits (recycled source).","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Albian microfossils in the calcarenite limestone from Dopplerhütte and Tulbingerkogel quarries (Northern Zone of the Rhenodanubian Flysch Zone, eastern Austria)","authors":"A. Ślączka, M. Gasiński, G. Wessely, P. Wójcik-Tabol","doi":"10.17738/AJES.2016.0011","DOIUrl":"https://doi.org/10.17738/AJES.2016.0011","url":null,"abstract":"Calcareous arenitic rocks exposed in the Dopplerhutte and Tulbingerkogel quarries northwest of Vienna were studied to establish their stratigraphic age. The whole succession is a part of the “Northern Zone” – the Tulbingerkogel thrust sheet – which represents the external part of the Wienerwald Flysch. These rocks were regarded commonly as Neocomian, however the analyses of the foraminifera within the intercalations of marly limestones proved the presence of Globorotalia sp. and assemblages with the index species Spiroplectinata annectens (Parker et Jones). Therefore, the depositional age of the studied rocks can be estimated neither older than Albian nor younger than Cenomanian. This indicates that also during the Albian calcareous sedimentation persisted within the northernmost unit of the Rhenodanubian Flysch Zone, which probably represented a detached part of the southern slope of the European continental margin and / or the Penninic Ocean. Es wurden die arenitischen Kalkgesteine, die in den Steinbruchen bei der Dopplerhutte und am Tulbinger Kogel nordlich von Wien aufgeschlossen sind, einer Studie unterzogen, um ihr stratigraphisches Alter zu erharten. Die gesamte Abfolge ist Teil der „Nordzone“ – Tulbingerkogel Schuppe – welche den externen Abschnitt des Wienerwald-Flysches vertritt. Diese Gesteine wurden herkommlich als Neokom- Klippen bezeichnet, jedoch erbrachten Untersuchungen der Foraminiferen aus Einschaltungen von mergeligen Kalken den Nachweis der Anwesenheit von Vergesellschaftungen mit Globorotalia sp. und der Leitform Spiroplectinata annectens (Parker et Jones). Daher konnen nach der Altersabschatzung die untersuchten Gesteine nicht alter als Albium und nicht junger als Cenomanium sein. Dies zeigt an, dass im jungeren Albium kalkige Sedimentation innerhalb der Nordzone andauerte, welche letztere wahrscheinlich einen abgetrennten Teil des sudlichen Hanges der Europaischen Platte bzw des penninischen Ozeans darstellt.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67599130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrophysical approach for estimating porosity, clay volume, and water saturation in gas-bearing shale: A case study from the Horn River Basin, Canada","authors":"Taeyoun Kim, Seho Hwang, S. Jang","doi":"10.17738/AJES.2016.0022","DOIUrl":"https://doi.org/10.17738/AJES.2016.0022","url":null,"abstract":"Shale gas exists partly as a gas adsorbed to clay mineral and partly as a free gas within the pores. To evaluate a shale gas reservoir and calculate total gas content, it is essential to accurately analyze porosity, clay volume, and water saturation. In this study, we estimate these factors for the Horn River Basin using various types of well log data such as density log, sonic log, resistivity log, and neutron porosity log. Because a simple density porosity equation results in unreasonable fluid densities, we estimate porosity using total organic carbon. Based on brittleness, an empirical equation for clay volume is defined. Because the correlation coefficient between core-tested clay volume and water saturation is greater than 0.9, the empirical equation for water saturation is also defined in terms of brittleness. For the shale gas reservoir in the Horn River Basin, porosity can be calculated by using a linear equation with the density log, and clay volume and water saturation can be calculated by using a linear relationship with Young’s modulus and Poisson’s ratio. This study suggests that porosity, clay volume, and water saturation models can be established using the elastic model built on seismic inversion.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67599217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aquifer geochemistry of crystalline rocks and Quaternary deposits in a high altitude alpine environment (Kauner Valley, Austria)","authors":"T. Strauhal, C. Prager, B. Millen, C. Spötl, C. Zangerl, R. Brandner","doi":"10.17738/AJES.2016.0002","DOIUrl":"https://doi.org/10.17738/AJES.2016.0002","url":null,"abstract":"In the Upper Kauner Valley of the Tyrolean Central Alps in Austria, some of the slopes, consisting of crystalline bedrock covered by Quaternary deposits, host groundwater of remarkable chemical composition. The bedrock consists mainly of a thick paragneiss series with intercalations of orthogneiss and amphibolite belonging to the Ötztal-Stubai Basement Complex. These metamorphic rocks are ubiquitously fractured and the fracture surfaces are coated with Fe-(hydr-)oxides and chlorite but also carbonates. Sul phides occur as dispersed accessory crystals and locally as small ore deposits. During the Quaternary, the valley floor, slopes, and cirques were covered by clastic sediments of differing thicknesses. A striking feature of the valley is that the slopes have been affected by different types of mass movements (rockfalls, debris flows and deep-seated rockslides). Data from extensive (hydro)geological field surveys, tunnels (exploration drift and water conduction galleries) and exploration drillings indicate that the groundwater preferentially flows within zones of highly weathered bedrock (i.e. the saprolite), brittle fault and fracture zones, deep-seated rockslides, and in the conductive Quaternary deposits, i.e. the talus, colluvium, debris flow and alluvial deposits. Interestingly, unusually high amounts of total dissolved solids (>1000 mg / l) were measured in some spring waters. Tritium and δO values indicate short residence times (<5 years) and the analysis of δO and δH data shows that the groundwater is of meteoric origin and that no fractionation or evaporation processes, leading to increased mineralisation, have taken place. Ca and Mg are the dominant cations and SO4 and HCO3 are the major anions present. Data correlation shows that the electric conductivity (EC) of the waters increases with increasing Ca, Mg and SO4 concentration, but not with HCO3. Low δS values indicate that the dissolved sulphate can be attributed to the oxidation of sulphides. Accordingly, the dissolution of carbonate fracture fillings and the oxidation of pyrite and other sulphides are regarded as the main processes responsible for the mineralised groundwater in the study area. Im hinteren Kaunertal der Tiroler Zentralalpen, welches aus metamorphen Gesteinen aufgebaut und durch quartäre Ablagerungen bedeckt wird, tritt Grundwasser von bemerkenswerter chemischer Zusammensetzung auf. Das Festgestein ist Teil des ÖtztalStubai-Komplexes und besteht vorwiegend aus mächtigen Paragneis-Serien mit Einschaltungen aus Orthogneis und Amphibolit. Diese metamorphen Gesteine treten durchgehend geklüftet auf. Die Kluftflächen weisen Fe-(hydr-)oxide und Chlorit sowie Karbonat überzüge auf. Sulfide treten einerseits feinverteilt akzessorisch und andererseits als kleine Erzkörper auf. Im Quartär wurden klastische Sedimente unterschiedlicher Mächtigkeiten im Talboden, auf den Hängen und in hochgelegenen Karen abgelagert. Ein besonderes Merkmal des Tales sind verschiedene Typen von Mas","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrology and geochemistry of metabasalts from the Taoxinghu ophiolite, central Qiangtang, northern Tibet: Evidence for a continental back-arc basin system","authors":"Yan-wang Wu, Cai Li, Meng-jing Xu, S. Xiong, Zheng-guo Fan, Chao-Ming Xie, Ming Wang","doi":"10.17738/AJES.2016.0012","DOIUrl":"https://doi.org/10.17738/AJES.2016.0012","url":null,"abstract":"Newly discovered ophiolitic metabasalts in the Taoxinghu area of central Qiangtang on the Qinhai-Tibet Plateau, here described for the first time, have important implications for reconstructions of the tectonic history of the Paleo-Tethys Ocean. Most of the metaba- salts belong to the tholeiitic basalt series and most have undergone greenschist-facies metamorphism. The distribution of rare earth elements and trace elements shows that the rocks are typical of sub-continental margin arc-basin lavas, similar to the environment of formation of the present-day Okinawa lava, suggesting that the Taoxinghu metabasalts represent the upper portions of a sup- ra-subduction zone (SSZ)-type ophiolite that formed in a continental back-arc basin tectonic environment. The Taoxinghu metaba- salts are mainly sourced from a depleted spinel mantle-source region, with a spinel lherzolite content equivalent to partial melting of 6 %-25 %. In addition, lava compositions were likely affected by melting of sediments during subduction, while the influence of aqueous fluids was minor. Combining with the existing knowledge on the ophiolites of Longmuco-Shuanghu-Lancang suture zone (LSLSZ), an evolutionary model is proposed. The LSLSZ Paleo-Tethys Ocean basin may have started to form during the Cambrian or earlier, and subducted in the early Carboniferous. As subduction proceeded, a continental back-arc basin was developed, the site of generation of most of the Taoxinghu metabasalts. The LSLSZ Paleo-Tethys Ocean finally closed in the Triassic.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative finite strain analysis of high-grade metamorphic rocks within the Mae Ping shear zone, western Thailand","authors":"Peekamon Ponmanee, P. Kanjanapayont, B. Grasemann, U. Klötzli, M. Choowong","doi":"10.17738/AJES.2016.0017","DOIUrl":"https://doi.org/10.17738/AJES.2016.0017","url":null,"abstract":"The NW trending Mae Ping shear zone exposes high-grade metamorphic rocks, the so called Lansang gneiss in the Tak region, western Thailand. The lithologies within the strike-slip zone mainly consist of orthogneisses and paragneisses. Using Fry’s method for 2-dimensional strain analysis we find that the averaged finite strain ratio (R s ) of the XY-plane is R s = 1.35-1.69. Based on the kinematic vorticity analysis of the mylonitic gneisses in the shear zone, the kinematic vorticity number is W k = 0.8-1.0 with an average of W k = 0.95. The results imply that the homogeneously deforming rocks within the Mae Ping shear zone have a strong simple shear component with a minor pure shear contribution of about 15 %. The kinematic indictors from both outcrop and micro scopic scales indicate a sinistral strike-slip shear sense. We conclude that the Mae Ping shear zone accommodated crustal scale sinistral transpression.","PeriodicalId":49319,"journal":{"name":"Austrian Journal of Earth Sciences","volume":"109 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67598869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}