Basin formation during the post-collisional evolution of the Eastern Alps: the example of the Lavanttal Basin     

Doris Reischenbacher  Reinhard F. Sachsenhofer 《International Journal of Earth Sciences》2013,102(2):517-543

The Miocene Lavanttal Basin formed in the Eastern Alps during extrusion of crustal blocks towards the east. In contrast to basins, which formed contemporaneously along the strike-slip faults of the Noric Depression and on top of the moving blocks (Styrian Basin), little is known about the Lavanttal Basin. In this paper geophysical, sedimentological, and structural data are used to study structure and evolution of the Lavanttal Basin. The eastern margin of the 2-km-deep basin is formed by the WNW trending Koralm Fault. The geometry of the gently dipping western basin flank shows that the present-day basin is only a remnant of a former significantly larger basin. Late Early (Karpatian) and early Middle Miocene (Badenian) pull-apart phases initiated basin formation and deposition of thick fluvial (Granitztal Beds), lacustrine, and marine (Mühldorf Fm.) sediments. The Mühldorf Fm. represents the Lower Badenian cycle TB2.4. Another flooding event caused brackish environments in late Middle Miocene (Early Sarmatian) time, whereas freshwater environments existed in Late Sarmatian time. The coal-bearing Sarmatian succession is subdivided into four fourth-order sequences. The number of sequences suggests that the effect of tectonic subsidence was overruled by sea-level fluctuations during Sarmatian time. Increased relief energy caused by Early Pannonian pull-apart activity initiated deposition of thick fluvial sediments. The present-day shape of the basin is a result of young (Plio-/Pleistocene) basin inversion. In contrast to the multi-stage Lavanttal Basin, basins along the Noric Depression show a single-stage history. Similarities between the Lavanttal and Styrian basins exist in Early Badenian and Early Sarmatian times.  相似文献   

The Antarctic viewpoint of the Central Paratethys: cause, timing, and duration of a deep valley incision in the Middle Miocene Alpine–Carpathian Foredeep of Lower Austria     

Holger Gebhardt  Reinhard Roetzel 《International Journal of Earth Sciences》2013,102(4):977-987

Global, glacio-eustatic sea-level changes massively influenced the depositional history of the Central Paratethyan region. Here, we correlate Middle Miocene global δ¹⁸O-shifts with ice volume changes on Antarctica and sea-level changes with corresponding phases of erosion (valley incision) and deposition in the Lower Austrian part of the Alpine–Carpathian Foredeep. This allows the exact dating of the valley formation. Two periods of positive δ¹⁸O-shifts resulted in sea-level drops of about 60 and 40 m, respectively. The first drop in the late Langhian (middle Badenian) at c. 13.9 Ma (Mi3b) was fast and caused severe erosion on the emerged foredeep. In a second, less pronounced step around 13.0 Ma (Mi4) in the middle Serravallian (late Badenian), the base level was further deepened after a period of alternating erosion and deposition. The combined sea-level change (80–120 m) fits well with the maximum thickness of Sarmatian sediments drilled within incised valley (110 m). The global sea-level falls affected not only the geological history of the foredeep. The intensive erosion (valley incision) is combined with delta progradation in the adjacent Vienna Basin. Due to this massive sea-level drop, the interruption of marine connections resulted in vast salt deposits and faunal crises within the Central Paratethys during this time.  相似文献   

Rocks,fabrics and magnetic anisotropy: an introduction to the issue in honour of František Hrouda     

Manish A. Mamtani  Martin Chadima  Helga de Wall  Reinhard O. Greiling 《International Journal of Earth Sciences》2012,101(3):605-607

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The formation of phosphoran olivine and stanfieldite from the pyrometamorphic breakdown of apatite in slags from a prehistoric ritual immolation site (Goldbichl, Igls, Tyrol, Austria)     

Philipp Schneider  Peter Tropper  Reinhard Kaindl 《Mineralogy and Petrology》2013,107(2):327-340

In this study we report P-rich olivine and the tric-calcium phosphate (TCP) stanfieldite in partially molten quartzphyllites from the ritual immolation site at the Goldbichl, near Innsbruck in the Tyrol, Austria. During partial melting, foamy patches of dark glassy material formed at the surface of the rocks and also as layers within the rocks. The pyrometamorphic rocks contain mostly the mineral assemblage olivine + orthopyroxene + plagioclase + spinel + glass. During the investigation of slag samples from this prehistoric ritual immolation site, extremely P-rich, apatite-bearing micro-domains were found. In these domains phosphoran olivine was found whose P contents are approaching the maximum P contents in olivine according to the experimental investigations of Boesenberg and Hewins (Geochim Cosmochim Acta 74:1923–1941, 2010). The textures within these domains indicate strongly disequilibrium conditions. The phosphoran olivines formed due to reactions involving apatite and the mineral assemblage of the quartzphyllites, and coexist with plagioclase and a tri-calcium phosphate phase (TCP) showing stanfieldite Ca₄(Mg, Fe²⁺, Mn²⁺)₅(PO₄)₆ composition. In terms of its chemical composition, olivine shows a wide range in composition with P ranging from 0.3 to 0.54 a.p.f.u, which corresponds to maximal 23 wt.% P₂O₅. These are the highest P-contents in olivine reported from rocks so far. The incorporation of P correlates with decreasing Si contents according to the charge balancing scheme $ 2{{\mathrm{P}}^{5+ }}+□{{\mathrm{M}}_{1,2 }}=2\mathrm{S}{{\mathrm{i}}^{4+ }}+{{\left( {\mathrm{M}\mathrm{g},\mathrm{Fe}} \right)}^{2+ }}{{\mathrm{M}}_{1,2 }} $ . Therefore P can only be incorporated in combination with a vacancy on the M_1,2 position. Micro-Raman spectroscopy of phosphoran olivines indicates that these olivines can easily be identified with this method due to the strong signals of the SiO₄ and PO₄ vibrations. The external vibrations of the M_1,2 sites at low wave-numbers are more complex than for P-free olivine. This might be due to the effect of P⁵⁺ on the M₁ ²⁺ and M₂ ²⁺ positions and the formation of vacancies on these sites. Since micro-Raman investigations of the TCP phase yielded no conclusive match with a known Raman spectrum of a phosphate mineral so far, therefore it is most likely that the TCP phase is stanfieldite, whose Raman spectrum has not been obtained yet. Schematical Schreinemakers analysis in the system CaO-Al₂O₃-FeO-SiO₂-P₂O₅-H₂O shows that P-rich olivine (fayalite-sarcopside solid solution) can form from mineral reactions involving chlorite, apatite and quartz and show that the occurrence of P-rich Fe-olivines spans a large T-range but is restricted to domains with high aSiO₂. The mineral assemblage in the P-rich micro-domains shows that the formation of phosphoran olivine is not only restricted to the interaction between bone material and rocks in slags from ritual immolation sites as suggested by Tropper et al. (Eur J Mineral 16:631–640, 2004) from the immolation site in Oetz but can form locally due to the pyrometamorphic breakdown of a P-rich accessory precursor phase such as apatite.  相似文献   

Paleolimnological evidence of mining and demographic impacts on Lac Dauriat, Schefferville (subarctic Québec, Canada)     

Laurence Laperrière  Marie-Andrée Fallu  Sonja Hausmann  Reinhard Pienitz  Derek Muir 《Journal of Paleolimnology》2008,40(1):309-324

Qualitative and quantitative analysis of fossil diatoms and geochemical signals preserved in the sediments of Lac Dauriat (subarctic Quebec) were performed to evaluate the impacts of nearby mining activity and the expansion of the town of Schefferville on the water quality of the lake, and to reconstruct the changes of its trophic status. The presence of taxa typical of nutrient-enriched environments (e.g., Cyclostephanos invisitatus, Nitzschia gracilis, Nitzschia perminuta) and the low percentages of chrysophytes were indicative of the advanced state of eutrophication of the lake during the peak of mining activity, and were evidence of the negative impacts of municipal waste on the water quality of Lac Dauriat. Sedimentary analysis of metals, notably lead, mercury, cadmium, bismuth, cobalt, copper and zinc, showed maximum concentrations between 1940 and 1960 with mining era to pre-development enrichment factors ranging from 4.5 to 7.9. The changes seen in recent sediments reflected 3 distinct stages in the recent history of this ecosystem: (a) the non-perturbed, pre-mining (1882–1939), (b) the perturbed, mining period (1939–1977) with accelerated eutrophication, and (c) the post-mining period (1977–1999) with indications of natural recovery of the system after the installation of a water treatment plant in 1975, the closing of the mine in 1983, and the subsequent exodus of the town’s population. Despite the trajectory towards a return to the lake’s natural conditions, water resource managers and (paleo-)limnologists should be alarmed that the impacts of past human disturbance are still in evidence more than 20 years after the closure of the mines, and that Lac Dauriat has yet to reach its natural state of the period preceding extreme anthropogenic impact.  相似文献   

Establishing Holocene sediment core chronologies for northern Ungava lakes, Canada, using humic acids (AMS C) and Pb     

milie Saulnier-Talbot  Reinhard Pienitz  Thomas W. Stafford Jr. 《Quaternary Geochronology》2009,4(4):278-287

The absence of datable macrofossils in six sediment cores recovered from northern Ungava (Canada) lakes constituted a major challenge for the establishment of reliable lacustrine chronologies for the Holocene. Consequently, AMS radiocarbon dating of humic acids was used to assess age–depth in the cores. The reliability of the radiocarbon results near some of the core tops was evaluated through ²¹⁰Pb dating. The offset of sediment radiocarbon ages with their most probable time of formation and deposition in the lakes was found to be in the order of about 1000 years for recently deposited sediments. However, the basal dates in one core covering the entire postglacial period yielded a remarkable fit with previously established dates performed on marine shells at the maximum marine limit. Hence, the aim of this study was to describe how the two dating methods can be combined to address some of the problems paleolimnologists face when trying to assign ages to high-latitude lake sediment records. Suggestions are made for improving the quality of age–depth models developed in future studies for northernmost Québec and other comparable regions where paleolimnologists must deal with the combined challenges of very slow sediment accumulation rates in lakes, an extreme paucity of datable material and the sequestration of old carbon in the watersheds.  相似文献   

Mineralogical and geochemical alteration of low-grade metamorphic black slates due to oxidative weathering   总被引：1，自引：0，他引：1  

Cornelius Fischer  Christian Schmidt  Reinhard Gaupp 《Chemie der Erde / Geochemistry》2009,69(2):127-183

Low-grade metamorphic black slates of Silurian and Lower Devonian ages (from the Thüringisches Schiefergebirge in Germany) were investigated to identify mineralogical and geochemical alterations that occur during the oxidative weathering black slates.The slates exhibit an intense total organic carbon decrease (>90 wt%) due to oxidative weathering. The organic matter in black slate consists mainly of non-pyrolysable material with only minor portions of pyrolysable material. In contrast to the non-pyrolysable organic matter, the concentration of pyrolysable organic matter is not decreased during weathering. Heating experiments have yielded information about a potential protection of pyrolysable organic matter against weathering, which is probably caused by a structural configuration or the intergrowth of organic matter and illite.The slates consist mainly of illite. Iron oxide (goethite) and phosphate encrustations were formed on slate surfaces as a result of oxidative and acid weathering of both iron sulfide and monazite. Kaolinite often occurs as an older encrustation beneath the iron oxide encrustations. Encrustations of iron oxide and phosphate are major sinks for trace elements, released during oxidative weathering.  相似文献   

The role and conditions of second-stage mantle melting in the generation of low-Ti tholeiites and boninites: the case of the Manihiki Plateau and the Troodos ophiolite     

Roman?Golowin  Maxim?PortnyaginEmail author  Kaj?Hoernle  Alexander?Sobolev  Dimitry?Kuzmin  Reinhard?Werner 《Contributions to Mineralogy and Petrology》2017,172(11-12):104

High-Mg, low-Ti volcanic rocks from the Manihiki Plateau in the Western Pacific share many geochemical characteristics with subduction-related boninites such as high-Ca boninites from the Troodos ophiolite on Cyprus, which are believed to originate by hydrous re-melting of previously depleted mantle. In this paper we compare the Manihiki rocks and Troodos boninites using a new dataset on the major and trace element composition of whole rocks and glasses from these locations, and new high-precision, electron microprobe analyses of olivine and Cr-spinel in these rocks. Our results show that both low-Ti Manihiki rocks and Troodos boninites could originate by re-melting of a previously depleted lherzolite mantle source (20–25% of total melting with 8–10% melting during the first stage), as indicated by strong depletion of magmas in more to less incompatible elements (Sm/Yb < 0.8, Zr/Y < 2, Ti/V < 12) and high-Cr-spinel compositions (Cr# > 0.5). In comparison with Troodos boninites, the low-Ti Manihiki magmas had distinctively lower H₂O contents (< 0.2 vs. > 2 wt% in boninites), ~ 100 °C higher liquidus temperatures at a given olivine Fo-number, lower fO₂ (ΔQFM < + 0.2 vs. ΔQFM > + 0.2) and originated from deeper and hotter mantle (1.4–1.7 GPa, ~ 1440 °C vs. 0.8–1.0 GPa, ~ 1300 °C for Troodos boninites). The data provide new evidence that re-melting of residual upper mantle is not only restricted to subduction zones, where it occurs under hydrous conditions, but can also take place due to interaction of previously depleted upper mantle with mantle plumes from the deep and hotter Earth interior.  相似文献   

Spatial patterns of submerged macrophytes and heavy metals in the hypertrophic, contaminated, shallow reservoir Lake Qattieneh/Syria     

Siba Hassan  Reinhard Böcker 《Limnologica》2010,40(1):54-60

Our investigation on macrophytes in Lake Qattieneh, a large, shallow reservoir in western Syria, is a first assessment of ecological status of this lake. We studied spatial distribution patterns of aquatic macrophyte vegetation and heavy metal concentrations to determine if they can be used as indicators of point sources of pollution. Industrial and municipal point sources at the lake shore increase nutrient load and contamination by heavy metals. Water analyses revealed high concentrations of some heavy metals at some littoral sites: Ni 88.7 μg L⁻¹, Cr 49.99 μg L⁻¹, Co 14.38 μg L⁻¹, and Cu 11.65 μg L⁻¹. Despite hypertrophic conditions and high heavy metal contamination, we recorded several submerged macrophyte species with heterogeneous spatial distribution patterns. Whereas Potamogeton pectinatus L. dominates in the eastern part of the lake, near industrial point sources, both Myriophyllum spicatum L. and Potamogeton lucens L. form extended patches in the western part of the lake. The shallow, littoral areas near villages are dominated by Ranunculus trichophyllus Chaix in Villars and Ceratophyllum demersum L. The west-east gradient in nutrient and heavy metal concentrations in waters and sediments are reflected by the spatial distribution of submersed species. While the heavy metal concentrations of the water body vary considerably in different seasons, the contents in submersed macrophytes integrate seasonal variations of longer time periods. Spatial distribution and tissue accumulation of littoral macrophyte species reflect the environmental conditions at respective sites such as heavy metal contents in water and sediment.  相似文献   

ISCO for Groundwater Remediation: Analysis of Field Applications and Performance     

Friedrich J. Krembs  Robert L. Siegrist  Michelle L. Crimi  Reinhard F. Furrer  Benjamin G. Petri 《Ground Water Monitoring & Remediation》2010,30(4):42-53

A critical analysis of in situ chemical oxidation (ISCO) projects was performed to characterize situations in which ISCO is being implemented, how design and operating parameters are typically employed, and to determine the performance results being achieved. This research involved design of a database, acquisition and review of ISCO project information, population of the database, and analyses of the database using statistical methods. Based on 242 ISCO projects included in the database, ISCO has been used to treat a variety of contaminants; however, chlorinated solvents are by far the most common. ISCO has been implemented at sites with varied subsurface conditions with vertical injection wells and direct push probes being the most common delivery methods. ISCO has met and maintained concentrations below maximum contaminant levels (MCLs), although not at any sites where dense nonaqueous phase liquids (DNAPL) were presumed to be present. Alternative cleanup levels and mass reduction goals have also been attempted, and these less stringent goals are met with greater frequency than MCLs. The use of pilot testing is beneficial in heterogeneous geologic media, but not so in homogeneous media. ISCO projects cost $220,000 on average, and cost on average $94/yd³ of target treatment zone. ISCO costs vary widely based on the size of the treatment zone, the presence of DNAPL, and the oxidant delivery method. No case studies were encountered in which ISCO resulted in permanent reductions to microbial populations or sustained increases in metal concentrations in groundwater at the ISCO-treated site.  相似文献