Ali Soliman

Lower and Middle Miocene biostratigraphy, Gulf of Suez, Egypt based on dinoflagellate cysts and calcareous nannofossils

This is the first detailed stratigraphic correlation of Lower and Middle Miocene deposits in the Gulf of Suez, Egypt using dinoflagellate cysts. The correlation is based on 273 ditch-cutting samples from five onshore boreholes located along the southwestern margin of the Gulf of Suez. The interval studied is represented by the Nukhul, Rudeis and Kareem formations of the Gharandal Group, and the lower part of the Belayim Formation of the Ras Malaab Group. These Miocene deposits unconformably overlie the Lower or lower Middle Eocene. The dinoflagellate cyst record is more diverse than previously reported and many taxa are documented for the first time in Egypt. Five biozones are established and tied to a chronostratigraphic framework by calibration to calcareous nannofossils (NN biozones) obtained from the same set of samples: (1) Lingulodinium machaerophorum Assemblage Biozone (GOSl), Aquitanian through mid-Burdigalian; (2) Exochosphaeridium insigne Taxon-range Biozone (GOS2), lower through mid-Burdigalian; (3) Apteodinium spiridoides Interval Biozone (GOS3), mid-Burdigalian through lower Langhian; (4) Cleistosphaeridium placacanthum Interval Biozone (GOS4), upper Burdigalian, Langhian, and lower Serravallian?); and (5) Polysphaeridium zoharyi Assemblage Biozone (GOS5), upper Langhian and Serravallian? Comparison with other Miocene biozonations from the Mediterranean, Central Paratethys, North Atlantic region, and eastern USA indicate that the highest occurrences of Apteodinium spiridoides, Cordosphaeridium cantharellus, Distatodinium paradoxum, Exochosphaeridium insigne and Cleistosphaeridium placacanthum, and the lowest occurrences of Exochosphaeridium insigne and Sumatradinium soucouyantiae are important datums, whereas the lowest occurrences of Hystrichosphaeropsis obscura, Labyrinthodinium truncatum, and Operculodinium? borgerholtense provide useful supporting age control.

Upwelling conditions in the Early Miocene Central Paratethys Sea

Upwelling conditions in the Early Miocene Central Paratethys Sea Evidence for regional upwelling conditions in the Central Paratethys Sea is presented for mid-Burdigalian (early Ottnangian) times. The oceanographic phenomenon is detected in clay-diatomite successions along the steep escarpment of the Bohemian Massif in the eastern North Alpine Foreland Basin. Interpretations are based on a multiproxy data-set including published sedimentological and paleontological data, newly performed stable isotope measurements (δ18O, δ13C) of foraminifers and bulk sediment samples, and analyses of dinoflagellate cyst assemblages. The revealed stable isotope values of planktonic foraminifers point to upwelling: low δ13C values indicate strong mixing of surface waters with rising nutrient-rich waters, high δ18O values reflect cool sea surface temperatures (SST). Temperature calculations give SSTs ranging from 10-14 °C. Cool SSTs and high productivity are additionally supported by bulk sediment analyses. Assemblages of dinoflagellate cysts indicate a distal-shelf environment with nutrient-rich waters. Westerly winds and tidal currents are discussed as potential driving forces behind the local upwelling event. As mid-Burdigalian geography favoured strong current patterns in the Central Paratethys as documented in the sedimentary record from the Rhône Basin to Hungary upwelling might have been a more common phenomenon in this epicontinental sea than currently known.

The Dababiya corehole, Upper Nile Valley, Egypt: Preliminary Results

Author Posting.

Stratigraphic re-evaluation of the stratotype for the regional Ottnangian stage (Central Paratethys, middle Burdigalian)

The Ottnangian stage represents the middle Burdigalian (c. 18.1-17.2 Ma) within the regional stratigraphic concept for the Central Paratethys. The section Ottnang-Schanze in the North Alpine Foreland Basin of Upper Austria has been defined as its stratotype by Rogl et al. (1973). We present an updated strati- graphic evaluation of the section based on biostratigraphy of foraminifers, dinoflagellate cysts and calcare- ous nannoplankton as well as magnetostratigraphy. In agreement with earlier studies, assemblages of benthic foraminifers (co-occurrence of Amphicoryna ott - nangensis and Sigmoilopsis ottnangensis, mass-occurrences of Lenticulina inornata) document a late early Ottnangian age. Dinoflagellate cyst Exochosphaeridium insigne is recorded for the first time in the early Ott- nangian and its occurrence together with Apteodinium spiridoides, Cordosphaeridium cantharellus and Glaphyrocysta reticulosa s. l. extends the regional dinoflagellate zone Ein from the middle to the early Ott - nangian. On a global scale, the revealed marker species indicate zone D17a (middle-late Burdigalian). Cal- careous nannoplankton assemblages with the very rare occurrence of Sphenolithus cf. belemnos and S. aff. heteromorphus show remarkable affinities to Mediterranean nannoplankton zone MNN3b. Together with the frequent occurrence of Helicosphaera ampliaperta and the absence of Triquetrorhabdulus carinatus an assignment to standard nannoplankton zone NN3 (early-middle Burdigalian) is indicated. Magnetostratigraphy revealed an inverse polarisation for the outcrop. In combination with the biostrati- graphic age constraints and the present correlation of the Ottnangian to the Bur3 sea-level cycle the section belongs to polarity chron C5Dr.2r. For the first time, an absolute age between 17.95-18.056 Ma for the stra- totype can be inferred.

High-resolution analysis of upper Miocene lake deposits: Evidence for the influence of Gleissberg-band solar forcing

A high-resolution multi-proxy analysis was conducted on a 1.5-m-long core of Tortonian age (~ 10.5 Ma; Late Miocene) from Austria (Europe). The lake sediments were studied with a 1-cm resolution to detect all small-scale variations based on palynomorphs (pollen and dinoflagellate cysts), ostracod abundance, geochemistry (carbon and sulfur) and geophysics (magnetic susceptibility and natural gamma radiation). Based on an already established age model for a longer interval of the same core, this sequence can be limited to approx. two millennia of Late Miocene time with a resolution of ~ 13.7 years per sample. The previous study documented the presence of solar forcing, which was verified within various proxies on this 1.5-m core by a combination of REDFIT spectra and Gaussian filters. Significant repetitive signals ranged in two discrete intervals corresponding roughly to 55–82 and 110–123 years, fitting well within the lower and upper Gleissberg cycle ranges. Based on these results, the environmental changes along the 2000-year Late Miocene sequence are discussed. No major ecological turnovers are expected in this very short interval. Nonetheless, even within this brief time span, dinoflagellates document rapid changes between oligotrophic and eutrophic conditions, which are frequently coupled with lake stratification and dysoxic bottom waters. These phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria. The pollen record indicates rather stable wetland vegetation with a forested hinterland. Shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms. These are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction. Such influence is most likely caused by solar cycles, leading to a change in source area for the input into the lake. Furthermore, these solar-induced variations seem to be modulated by longer solar cycles. The filtered data display comparable patterns and modulations, which seem to be forced by the 1000-year and 1500-year cycles. The 1000-year cycle modulated especially the lake surface proxies, whereas the 1500-year cycle is mainly reflected in hinterland proxies, indicating strong influence on transport mechanisms.

Oligocene dinoflagellate cysts from the North Alpine Foreland Basin: new data from the Eggerding Formation (Austria)

Oligocene dinoflagellate cysts from the North Alpine Foreland Basin: new data from the Eggerding Formation (Austria) In spite of detailed geological and geophysical investigations, information available on palynostratigraphy for the successions deposited in the Austrian part of the North Alpine Foreland Basin (NAFB) is scanty. For the first time, relatively diverse and well preserved Oligocene dinocyst assemblages, comprising 53 genera and 138 species, are presented from the organic-rich sediments of the Eggerding Formation. These assemblages contribute to the biostratigraphy of the Oligocene deposits within the NAFB. Dinocysts such as Chiropteridium lobospinosum, Membranophoridium aspinatum, Cordosphaeridium spp., Enneadocysta spp., Deflandrea spp., Spiniferites/Achomosphaera group, Hystrichokolpoma spp., Apteodinium spp., Glaphyrocysta/Areoligera complex and Wetzeliella spp. represent the main palynological elements. The occurrence of Chiropteridium spp., Tuberculodinium vancampoae, Distatodinium biffii and Wetzeliella gochtii is of particular importance for regional correlations within the Lower Oligocene sediments. A comparison with age-controlled assemblages from the North Sea Basin, Carpathian and circum-Mediterranean regions substantiate the attribution to the Rupelian. Lack or sporadic occurrence of the oceanic taxa (e.g. Nematosphaeropsis and Impagidinium) and dominance of Glaphyrocysta/Areoligera indicate an inner-neritic marine setting during the deposition of the studied intervals. Although, it is difficult to reconstruct precisely the climatic conditions based on the recorded dinocysts, warm? sea surface water is suggested. A variation in salinities is interpreted based on the abundances of Homotryblium spp. The abundance of Peridiniaceae taxa (e.g. Lejeunecysta, Wetzeliella, and Deflandrea) indicates nutrient-rich surface water.

Mendicodinium mataschenensis: a new endemic dinoflagellate cyst from the Late Miocene (Tortonian) of Lake Pannon (Austria)

The organic-walled dinoflagellate cyst Mendicodinium mataschenensis is introduced here as a new species. The taxon derives from lower Tortonian clays from the Mataschen clay pit in Styria, Austria. These deposits formed in Lake Pannon, which was characterized throughout the Late Miocene by its highly endemic and rapidly evolving biota. As most species of Mendicodinium are known from restricted marine and brackish paleoenvironments, its occurrence in Lake Pannon may be considered further evidence for the brackish water conditions prevailing in this lake.

A calcite crisis unravelling Early Miocene (Ottnangian) stratigraphy in the North Alpine–Carpathian Foreland Basin: a litho- and chemostratigraphic marker for the Rzehakia Lake System

Abstract Within the Lower Austrian part of the North Alpine Foreland Basin (NAFB), up to 1000 m of sediments were deposited throughout the Ottnangian (Early Miocene, Burdigalian). According to homogeneous compositions and sparse biostratigraphic resolution, a consistent stratigraphic concept from the basin margins into the foreland depocenter was still lacking. New investigations on several deep drill cores throughout the basin provide comprehensive sedimentological, mineralogical, chemical and micropaleontological data. A calcite poor, fossil- and pyrite-free, smectite-rich, up to 800 m thick interval was identified and correlated to the time interval of the late Ottnangian brackish Rzehakia Lake System. For this section, we introduce the term Calcite Minimum Interval (CMI). We define the onset of the CMI by a sharp decrease of calcite contents and the disappearance of autochthonous (and reworked) calcareous nannofossils. We define the termination of the CMI by the permanent increase of pyrite contents and the reappearance of calcareous nannofossils. The CMI as a litho- and chemostratigraphical marker for the Rzehakia Lake System constitutes a stratigraphic key horizon. Within the NAFB in Lower Austria, its onset corresponds to the middle/upper Ottnangian transition while its termination correlates roughly to the Ottnangian / Karpatian boundary. This allows a precise definition, identification and correlation of (upper) Ottnangian stratigraphic units of the NAFB. For the central basinal parts of the Rzehakia Lake System, we introduce the new lithostratigraphic term Wildendürnbach Formation which correlates to the marginal Traisen Formation.

Facies, palaeogeography and stratigraphy of the lower Miocene Traisen Formation and Wildendürnbach Formation (former “Oncophora Beds”) in the Molasse Zone of Lower Austria

Abstract A detailed study of OMV wells throughout the Lower Austrian Molasse Basin demonstrates the existence of a distinct and synchronous upper Ottnangian (lower Miocene) stratigraphic signal, the Calcite Minimum Interval (CMI). It corresponds to the depositional phase of the Rzehakia Lake System. This signal is interpreted to be of chronostratigraphic importance as an expression of palaeoclimate and related sea-level change. It is represented by the brackish Traisen Formation, which crops out south of the Danube. The Traisen Formation correlates with sands and shales in OMV wells to the north, termed Wildendürnbach Formation. However, the CMI underlies a marine unit, the so-called “Oncophora Beds” (also known as Rzehakia Beds) as reported from OMV wells in the north at the border to the Czech Republic. We demonstrate that these former “Oncophora Beds” are younger, i.e. of Karpatian age, than originally assumed. Therefore, these deposits cannot be correlated to the late Ottnangian Traisen Formation. This may solve the problem of contradicting interpretations concerning the depositional environment of both units, which were correlated to each other in the past. As no Rzehakia bivalves (formerly Oncophora) are described from these former “Oncophora Beds”, we recommend to avoid using the term for these turbiditic sands. Instead, we attribute these deposits to the fully marine Karpatian Laa Formation. These new findings, which are in accordance with published data from the Czech Republic, indicate two (in time and space) independent sedimentary systems and sand deposition centres for the Traisen Formation and the massive sands attributed as “Oncophora Beds” around Wildendürnbach. A late Ottnangian system in the south delivered the material of the Traisen Formation from the Alps and a Karpatian system delivered the clastic material of the massive sands of the Laa Formation from the east.