scholarly journals Clay mineralogy of Miocene mudstones from the Lower Austrian Molasse Basin

2020 ◽  
Vol 113 (1) ◽  
pp. 125-138
Author(s):  
Maria Meszar ◽  
Susanne Gier ◽  
Markus Palzer-Khomenko ◽  
Wolfgang Knierzinger ◽  
Michael Wagreich
Keyword(s):  
Chemical Weathering ◽  
Early Stage ◽  
Clay Mineralogy ◽  
Foreland Basin ◽  
External Source ◽  
Eastern Alps ◽  
Molasse Basin ◽  
The North ◽  
Stratigraphic Model ◽  
North Alpine Foreland Basin

AbstractRecent studies established the lithological and chemical sediment evolution in the Lower Austrian Molasse Basin (LAMB), a part of the North Alpine foreland basin, during the Early Miocene. In this study, we aim to integrate the clay mineralogy of seven wells across the LAMB with a newly proposed lithostratigraphy, and to infer implications for provenance, palaeo-geography and palaeoclimate. The results of our qualitative and quantitative evaluation of the clay-sized fraction with x-ray diffractometry largely support the stratigraphic model. The early stage of foreland basin formation (Egerian/Eggenburgian?) is represented by kaolinite contents up to 93 % in the clay sized fraction. This indicates an orogen-external source, i.e. the Bohemian Massif, and erosion of intensively chemical weathered products during this early Molasse basin stage. The over-lying marine Robulus Schlier (lower/middle Ottnangian) is characterized by a distinctly reduced kaolinite content and overall increased illite content compared to the other formations. Illite was predominantly provided from denudation of the rising Eastern Alps, i.e. characterizing the orogen-internal provenance. The pelites of the overlying carbonate poor Traisen Formation (upper Ottnangian) show again a higher kaolinite and smectite content. In the largely coeval basinal Wildendürnbach Formation, smectite reaches up to 70 % in the clay sized fraction. Peak smectite values may be linked to volcanic ash input from the nearby Carpathian volcanic arc. Generally rising smectite versus illite ratios during the Ottnangian-Karpatian could point to a warming and intensified chemical weathering of the rising Alpine orogen.

The Evolution of the Paleo-Danube Deltas of the Lower Pannonian in the Vienna Basin 

2021 ◽  
Author(s):  
Arthur Borzi ◽  
Werner E. Piller ◽  
Mathias Harzhauser ◽  
Wolfgang Siedl ◽  
Philipp Strauss
Keyword(s):  
Water Depth ◽  
Foreland Basin ◽  
Eastern Alps ◽  
Depositional Environments ◽  
Terminal Phase ◽  
Vienna Basin ◽  
Lake Pannon ◽  
The North ◽  
Lateral Extrusion ◽  
North Alpine Foreland Basin

<p><strong>ABSTRACT</strong></p><p>The Vienna Basin is a rhombohedral SSW-NNE oriented Neogene extensional basin that formed along sinistral fault systems during Miocene lateral extrusion of the Eastern Alps. The basin fill consists of shallow marine and terrestrial sediments of early to late Miocene age reaching a thickness of 5500 m in the central part of the basin. The early Pannonian was a crucial time in the development of the Vienna Basin, as It coincided with the formation of Lake Pannon. The lake formed at 11.6 Ma when a significant regressive event isolated Lake Pannon from the Paratethys Sea, creating lacustrine depositional environments. At that time the delta of the Paleo-Danube started shedding its sediments into the central Vienna Basin. Based on an existing age model delta deposition commenced around 11.5 Ma and continued until 11.1 Ma. These subsurface deltaic deposits of the Hollabrunn-Mistelbach Formation represent the coeval fluvial deposits of the Paleo-Danube in the eastern plains of the North Alpine Foreland Basin. Therefore, the Palaeo-Danube represents an extraordinary case in where coeval fluvial and deltaic deposits of a Miocene river are continuously captured.</p><p>This study provides an interpretation of depositional architecture and depositional environments of this delta in the Austrian part of the central Vienna Basin based on the integration of 3D seismic surveys and well data. The mapped delta has an area of about 580 km<sup>2</sup>, and solely based on the geometry we classify the delta as a mostly river – dominated delta with significant influence of wave – reworking processes. For seven time slices paleogeographic maps are created, showing the interplay between the lacustrine environments of Lake Pannon, delta evolution and fluvial systems incising in the abandoned deltaplain. Onlaps between single deltalobes indicate a northward-movement of the main distributary channel. Approximate water-depth estimates are carried out with in-seismic measurements of the true vertical depth between the topset deposits of the delta and the base of the bottomset deposits. These data suggest a decrease of lake water depth from about 170 m during the initial phase of delta formation at 11.5 Ma to about 100 m during its terminal phase at 11.1 Ma. A major lake level rise of Lake Pannon around 11.1 Ma caused a flooding of the margins of the Vienna Basin, resulting in a back stepping of riverine deposits and termination of delta deposition in the study area.</p><p> </p>

scholarly journals Detailed Fluid Inclusion and Stable Isotope Analysis on Deep Carbonates from the North Alpine Foreland Basin to Constrain Paleofluid Evolution

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-23 ◽  
Author(s):  
Elena Mraz ◽  
Markus Wolfgramm ◽  
Inga Moeck ◽  
Kurosch Thuro
Keyword(s):  
Fluid Inclusions ◽  
Foreland Basin ◽  
Upper Jurassic ◽  
Molasse Basin ◽  
Drill Cuttings ◽  
The North ◽  
North Alpine Foreland Basin ◽  
Alpine Foreland ◽  
Alpine Foreland Basin ◽  
Reservoir Evolution

The recent interest on environmentally friendly energy resources has increased the economic interest on the Upper Jurassic carbonate rocks in the North Alpine Foreland Basin, which serves as a hydrogeothermal reservoir. An economic reservoir use by geothermal fluid extraction and injection requires a decent understanding of porosity–permeability evolution of the deep laying Upper Jurassic strata at depths greater than 2000 m. The analysis of paleofluids caught in cements of the rock mass helps to determine the postdepositional reservoir evolution and fluid migration. Therefore, the high- and low-permeability areas of the Upper Jurassic in the North Alpine Foreland Basin referred to as Molasse Basin were analyzed by means of encountered postdepositional cements to determine the reservoir evolution. The cements were sampled at different hydrocarbon and geothermal wells, as well as at outcrops in the Franconian and Swabian Alb. To determine the composition and temperature of the paleofluids, fluid inclusions and cements of the Upper Jurassic carbonate rocks were analyzed by microthermometry and stable isotope measurements. Since drill cuttings are a rather available sample material compared to drill cores, a new microthermometry measurement method was achieved for the around 1 mm drill cuttings. Salinity and formation temperature of paleofluids in fluid inclusions and isotope data are consistent with previous studies and reveal a 5-stage evolution: the main cementation phases are composed of (I) the early diagenesis in limestones (200-400 m, 40-50°C), (II) early diagenetic dolomitization, and (III) burial dolomitization (1-2 km, II: 40-90°C; III: 70-100°C; 40 g/L NaCl equiv.), and (IV) late burial calcification (IIIa: 110-140°C, IIIb: 140-200°C) linked to tectonic features in the Molasse Basin. In the outcrop samples, a subsequent (V) cementation phase was determined controlled by karstification. In the southwest, an increase in salinity of the fluid inclusions in vein calcites, above the salinity of the Jurassic seawater, highlights the influence of basin fluids (diagenetic, evaporitic). In the other eastern wells, vein calcites have precipitated from a low saline fluid of around 10-20 g/L NaCl equiv. The low salinity and the isotope values support the theory of a continuous influence of descending meteoric fluids. Consequently, the Upper Jurassic seawater has been diluted by a meteoric fluid to a low saline fluid (<1 g/L), especially in areas with high permeability. Here, we show how a better understanding of cementation trajectory at depth can help to generate a better understanding of geothermal usability in deep carbonate reservoirs.

Chemical weathering response to extreme global warming during Paleocene-Eocene Hyperthermals, Southern Pyrenees, Spain

2021 ◽  
Author(s):  
Rocio Jaimes-Gutierrez ◽  
Thierry Adatte ◽  
Emmanuelle Puceat ◽  
Jean Braun ◽  
Sebastien Castelltort
Keyword(s):  
Climatic Change ◽  
Chemical Weathering ◽  
Numerical Models ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Foreland Basin ◽  
Isotopic Analysis ◽  
Feedback Mechanism ◽  
Horizon 2020 ◽  
Sediment Routing

&lt;p&gt;The Paleocene and early Eocene were periods yielding multiple hyperthermal events. The most pronounced of them was the Paleocene-Eocene Thermal Maximum (PETM), which was characterized by an abrupt increase in global temperature (5&amp;#8211;8 &amp;#176;C) over a short time (20 ka). A negative carbon isotope excursion marks the onset of the PETM, which resulted in the fast injection of CO&lt;sub&gt;2&lt;/sub&gt; into the ocean-atmosphere system, triggering global climatic changes. Geochemical, mineralogical, and sedimentological markers record the resulting increase in continental weathering. This is important, as enhanced chemical erosion influences both the CO&lt;sub&gt;2&lt;/sub&gt; concentration in the atmosphere and ocean acidity, generating a feedback mechanism. Hence, constraining the rates and intensity of weathering response can further clarify the causes for the PETM and Eocene hyperthermals. This study focuses on the well-preserved Pyrenean foreland basin and intends to assess the continental chemical weathering response of the sediment routing system during the PETM. Clay mineralogy is a climate-sensitive proxy, which records changes in continental erosion. Therefore, clay mineral proportions will be analyzed using X-ray diffraction and major element chemistry on clay-rich samples from the entire source-to-sink system (continental to deep marine deposits). Kaolinite and smectite will be separated from the detrital clay fraction and further subjected to &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;D isotopic analysis for paleoclimatic reconstruction. The combined Lu-Hf and Sm-Nd isotope systems in the clay fraction of the sediments will be used to track the evolution of chemical weathering intensity. The outcome of this project will serve to validate numerical models to understand erosion as a function of rapid climatic change. This topic is of keen interest, as the PETM and its sedimentological signal work as a natural analog for anthropogenically-induced climatic change. The project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 860383.&lt;/p&gt;

Bivalves from the Innviertel Group of Allerding in the North Alpine Foreland Basin (lower Miocene, Upper Austria)

2020 ◽  
Vol 297 (1) ◽  
pp. 47-100
Author(s):  
Oleg Mandic ◽  
Simon Schneider ◽  
Mathias Harzhauser ◽  
Wolfgang Danninger
Keyword(s):  
Shallow Water ◽  
Time Window ◽  
Foreland Basin ◽  
Migration Route ◽  
Central Paratethys ◽  
Seagrass Meadows ◽  
The North ◽  
North Alpine Foreland Basin ◽  
Alpine Foreland ◽  
Alpine Foreland Basin

During the Ottnangian (Burdigalian, early Miocene), the North Alpine Foreland Basin operated as a sea-way connecting the Central Paratethys Sea with the Rhône Basin in the Western Mediterranean. Within this short time window, an intensive faunal exchange between the two paleo-biogeographic units occurred, which is reflected in macrofossil assemblages. The extraordinarily rich fossil record of the study site, Allerding, located in the westernmost Central Paratethys, provides valuable insights into the composition and origins of the bivalve fauna colonizing the marine gateway. The site documents the early Ottnangian marine transgression over deeply weathered crystalline basement, grading from fossil bearing shallow water clay and sand into the open marine "Schlier" facies of the Ottnang Formation. Despite considerable taphonomic overprint including aragonite leaching and mechanical abrasion of bivalve shells under turbulent shallow-water conditions, a total of 46 species are recorded, including two new species (Lima allerdingensis n. sp. and Astarte danningeri n. sp.). The dominance of suspension feeders, and the presence of several deposit feeders and chemosymbiotic taxa point to well diversified inshore settings, including low intertidal mudflats, as well as seagrass meadows. An abundance of primary and secondary hardgrounds is reflected in the high number of cementing and byssate species, as well as in the occurrence of species drilling actively into hard substrate. Finally, the dominance of active burrowers suggests a patchwork of habitats, where sandy and muddy soft bottoms occur interspersed. Biostratigraphic analysis constrains the deposits to the early to middle Ottnangian, based on the presence of the index species Flexopecten davidi and the concurrence of several taxa, which have their last or first occurrences within this interval. These are predominantly taxa persisting into the Badenian, therefore allowing for a straightforward differentiation between late Eggenburgian and early Ottnangian assemblages. While a few Central Paratethys endemics reflect a continued semi-isolated position of the area, the majority of the newly arriving species are shared with the Mediterranean and NE Atlantic, documenting the establishment of a faunal migration route via the North Alpine Foreland Basin. In the present study the lectotypes of Nucula mayeri Hörnes, 1865, Saccella subfragilis (Hörnes, 1875) and Lucinoma wolfi (Hoernes, 1875) are designated.

Sign in / Sign up

Export Citation Format

Share Document