Sedimentary development and correlation of Mid-Late Devonian fore-reef deposits from Central Europe

Conference (2012, September 12)

INTRODUCTION: Despite the interest for the reconstruction of environmental changes over a long period of time, long-term successions have been relatively poorly investigated using a mutli-disciplinary ... [more ▼]

INTRODUCTION: Despite the interest for the reconstruction of environmental changes over a long period of time, long-term successions have been relatively poorly investigated using a mutli-disciplinary approach compared to short-term intervals such as Kačák, Taghanic, punctata, Kellwasser and Hangenberg events. Recently, BOULVAIN et al. (2010) compared two km-thick Eifelian-Frasnian sections from Belgium and Czeck Republic using magnetic susceptibility (SM) technique. Regardless the very different background of palaeogeography, sedimentary rate, facies and local sea-level changes history, a remarkable similarity in the MS trends can be observed between these two sections. These similarities brought questions on the nature of the long-term forcing parameters that were active at the inter-regional scale. In order to get a better understanding of the factors responsible of the inter-regional forcing, a detailed records of microfacies observations, MS measurements, selected trace and major elemental concentrations and conodonts biostratigraphy have been performed on two Middle to Upper Devonian successions from Germany (Sauerland, Burgberg) and Austria (Carnics Alps, Freikofel). CONODONT BIOSTRATIGRAPHY: In the Burgberg section, conodont biostratigraphy allowed us to confirm that the studied section extend from the Middle Givetian to the Lower Carboniferous. In the Freikofel section, it allowed to precisely identify the Eifelian-Givetian and the Frasnian-Famennian boundaries. SEDIMENTOLOGY: The field and microfacies observations allowed us to reconstruct the sedimentary environment and to highlight several major variations of this environment. In the Middle Devonian, both sections are mainly characterized by fore-reef sediments. In the Burgberg section, those fore-reef sediments, mainly correspond to bioclastic grainstone and rudstone related to gravity flow deposits derived from the shallow-water area. In the Freikofel section, the fore-reef area is dominated by breccia sediments suggesting a strong debris flow influence. Through the Upper Devonian the sedimentary setting evolves to an off-reef pelagic environment in both sections and even a basinal setting in the Burgberg section. Sediments are then dominated by thin-bedded and nodular limestone. In this Upper Devonian part, locally both sections, debris coming from the shallow-water area are still observed (suggestion: Even in the Upper Devonian, occasionally debris deriving from shallow water areas has been observed in both sections. MAGNETIC SUSCEPTIBILITY AND GEOCHEMISTRY: The mean MS values for the Burgberg and Freikofel sections are respectively 1,88x10-8m³/kg and 7,72x10-9m³/kg. Compared to the MSmarine standard of 5.5x10-8m³/kg defined by ELLWOOD et al. (2011) on the basis of ~11,000 marine rocks samples, our values are low, mostly in the Freikofel section, which could indicate a low terrestrial influx seaward during the Middle and Upper Devonian. Regarding the magnetic susceptibility curves from these two sections, several large-scaled trends can be highlighted. The evolution curves of some selected clastic input proxies such as Zr, Si, Al, Ti, Sr display similar large-scaled trends. This indicates that clastic input proxies and MS are inherently linked and MS techniques can thus be used here as a proxi for changes in source or amount or type of weathering (RIQUIER et al. 2010). Most of the long-term MS variations occurring in both sections are interpreted as being related to second order eustatic variations (T-R Cycles). Through this multi-disciplinary investigation, we would like to get a better idea on the causes of long-term trends in MS variations and to document the sedimentary changes in response to these long-term variations. Further aim is to develop the application of MS techniques as a correlation tools. BOULVAIN, F., DA SILVA, A-C., MABILLE, C., HLADIL, J., GERSL, M., KOPTIKOVA, L., SCHONABL P., 2010. Magnetic susceptibility correlation of km-thick Eifelian-Frasnian sections (Ardennes and Moravia). Geologica Belgica, 13/4, 309-318. ELLWOOD, B.B., ALGEO, T.J., EL HASSANI, A., TOMKIN, J.H., ROWE, H.D., 2011. Defining the timing and duration of Kačák Interval within the Eifelian/Givetian boundary GSSP, Mech Irdane, Morocco, using geochemical and magnetic susceptibility patterns. Palaeogeography, Palaeoclimatology, Palaeoecology, 304, 74-84. RIQUIER, L., AVERBUCH, O., DEVLEESCHOUWER, X., TRIBOVILLARD, N., 2010. Diagenetic versus detrital origin of the magnetic susceptibility variations in some carbonate Frasnian-Famennian boundary sections from Northern Africa and Western Europe: implications for palaeoenvironmental reconstructions. International Journal of Earth Sciences, 99, 57-73. [less ▲]

Multi-disciplinary research on long-term Middle to Upper Devonian fore-reef successions from Germany and Austria

in Kido, Erika; Suttner, Thomas; Werer, Piller (Eds.) et al Berichte des Institutes für Erdwissenschaften, Karl-Franzens-Universität Graz (2012, June)

Sedimentology of a Mid-Late Ordovician carbonate mud-mounds complex from the Katmandu nappe in Central Nepal

in ASF (Ed.) Livre des résumés (2011, November)

Sedimentology of a Mid-Late Ordovician carbonate mud-mound complex from the Katmandu nappe in central Nepal

in Journal of Asian Earth Sciences (2011), 42(3), 451-466

This sedimentological study of the Godavari quarry is the first relating to the Palaeozoic Tethyan sedimentary rocks of the Katmandu nappe (Central Nepal). Sedimentological analyses led to the ... [more ▼]

This sedimentological study of the Godavari quarry is the first relating to the Palaeozoic Tethyan sedimentary rocks of the Katmandu nappe (Central Nepal). Sedimentological analyses led to the identification of six microfacies belonging to a large carbonate mud-mound complex, which can be divided into mound, flank and off-mound main depositional settings. Identification of two dasycladaceans (Dasyporella cf. silurica (Stolley, 1893) and Vermiporella sp.) in the mound facies gives a Mid-Late Ordovician age to this newly discovered Godavari carbonate mud-mound, which makes this mound one of the oldest ever described in the Asian continent. The mound microfacies are characterized by a high micritic content, the presence of stromatactis and the prevalence of red coloured sediments (the red pigmentation probably being related to organic precipitation of iron). The flank microfacies are characterized by a higher crinoid and argillaceous content and the presence of bio- and lithoclasts concentrated in argillaceous lenses. Finally, the off-mound microfacies show very few bioclasts and a high argillaceous content. Palaeoenvionmental interpretation of microfacies, in terms of bathymetry, leads us to infer that the Godavari mud-mound started to grow in a deep environment setting below the photic and wave action zones and that it evolved to occupy a location below the fair weather wave base. Cementation of cavities within the mound facies underlines a typical transition from a marine to a burial diagenetic environment characterized by: (1) a radiaxial non luminescent feroan calcite cement (marine) showing a bright orange luminescent band in its middle part; (2) a bright zoned orange fringe of automorphic feroan calcite (meteoric phreatic); (3) a dull orange xenomorphic feroan calcite cement in the centre of cavities (burial) and (4) a saddle dolomite within the centre of larger cavities. The faunal assemblage (diversity and relative proportion) of the Godavari mound facies is dominated by crinoids and ostracods, which makes this carbonate mud-mound comparable to the Meiklejohn Peak mounds (Nevada). [less ▲]

Sedimentology of a continuous Givetian-Frasnian carbonate succession in Sauerland (Germany) and MS comparison with the time-equivalent ones of Ardennes (Belgium) and Moravia (Czech Republic).

in Suttner, Thomas; Kido, Erika; Piller, W. E. (Eds.) et al IGCP-596 Mid-Paleozoic climate and biodiversity, 19-24 septembre, Graz, Austria, Abstract book (2011)

Sedimentology and magnetic susceptibility on a continuous Middle Givetian to Lower Famennian fore-reef succession (Sauerland, Germany): a new example of MS study for long-distance correlations (Germany, Belgium, and Moravia)

in Koptikova, Leona; Hladil, Jindrich; Adamovic, Jiri (Eds.) Miroslav Krs conference: time, magnetism, records, systems and solution. The 2011 Annual IGCP-580 Meeting. Abstract Volume (2011)

Detailed sedimentology and magnetic susceptibility of a Givetian-Frasnian carbonate slope to basin system deposit related to the Brilon platform in the Rheinisches Schiefergebirge (Germany).

in 14th Bathurst meeting, Bristol University, Abstract Book (2011)

Lower Palaeozoic and Devonian carbonate facies in Nepal

Poster (2009, September 14)

Nepal is localized in the central part of the Himalayan arc. In uplift since the Cenozoic time, the Himalaya is traditionally divided into six lithotectonic zones extending in parallel belts. From north ... [more ▼]

Nepal is localized in the central part of the Himalayan arc. In uplift since the Cenozoic time, the Himalaya is traditionally divided into six lithotectonic zones extending in parallel belts. From north to south there are respectively: (1) the Trans-Himalayan batholith; (2) the Indus-Tsangpo suture zone; (3) the Tethyan (Tibetan) Himalaya; (4) the Higher (Greater) Himalaya; (5) the Lesser Himalaya; and (6) the Sub-Himalaya. This PhD thesis is focused on the Tethyan sedimentary rocks exposed in the Nepal Tethyan Himalaya belt and in the thrusting nappes belonging to the Lesser Himalaya. These nappes contain unmetamorphosed sedimentary rocks which might belong to the Tethyan sedimentary succession. The Tethyan Himalaya has preserved highly fossiliferous marine rocks deposited on the shelf and slope of the Indian continental margin from Late Proterozoic-Cambrian through early Eocene times. The main objective of this PhD thesis is to build a first sedimentological canvas for the Lower Paleozoic and Devonian carbonated rocks of Nepal which could be compared with the Belgian facies. This long distance comparison between the Belgian and the Nepalese basins will allow to have a better understanding of the phenomena that run the global carbonate sedimentation. The methods that will be used to achieve this work are: (1) bed by bed sampling; (2) petrographic analysis and facies modelling; (3) magnetic susceptibility analysis for correlations and eustatism and (4) paleontological datation. A first sedimentological campaign took place during the months of March and April 2009. It allowed to study three sections around Katmandu valley and two sections in the Annapurna range (Manang area). The sections studied around Katmandu (Pulchauki and Chandragiri Hill) belonged to the Formation of Chandragiri (Ordovician) and Godavari (Devonian) which are mainly constituted by carbonate rocks. The sections described in Manang area are mainly made-up by the terrigeneous rocks of the Dark Band, Tilicho Pass and Tilicho Lake Formation (Silurian to Lower Carboniferous). The diversity of facies observed in these five sections will be exposed. [less ▲]