Dinoflagellate cysts and acritarchs from the Miocene Zonderschot sands, Northern Belgium: stratigraphic significance and correlation with contiguous areas

A palynological investigation of the Miocene Zonderschot Sands (Berchem Formation) from the type locality Zonderschot (northern Belgium) has revealed the presence of a diverse dinoflagellate cyst and acritarch association. The dinoflagellates reflect a shallow marine environment, although the oceanic species Nematosphaeropsis and Impagidinium are prominent in the association and indicate the presence of an oceanic influence. This can be explained only by the depositional area being located at the very southern margin of the relatively isolated North Sea Basin during a period of maximum landward extent of the marine realm. A precise biostratigraphical correlation of the Zonderschot Sands with the Antwerpen Sands (Berchem Formation) from the Antwerp area is established. Biostratigraphical evaluation of key dinoflagellate cyst species indicates a latest Burdigalian (latest Early Miocene) -(earliest?) Langhian (early Middle Miocene) age for the Zonderschot Sands.Sedimentological and biostrati-graphical arguments are proposed that may indicate that the Génicot Formation was deposited just before, during and just after the Hirnantian (latest Ordovician) glaciation. This means the first indication of the presence of the latter in Belgium

Dinoflagellate cyst stratigraphy of the upper cretaceous of western Belgium

A detailed micropalaeontological analysis with dinoflagellate cysts of the Cretaceous sections intercepted by five wells in western Belgium allows a biostratigraphical correlation and a chronostratigraphical interpretation of the sediments concerned. The transgression of the Cretaceous sediments on the southern part of the Palaeozoic Brabant Massif appears to be strongly diachronous. In the Nieuwkerke and Oostduinkerke wells, situated south of the present day topographic crest of the Brabant Massif (Nieuwpoort-Oudenaarde), the transgression is dated as Late or latest Cenomanian and close to the crest in the Keiem well as Late Turonian. North of the crest, in the De Haan and Knokke wells, it is dated as Late Santonian. The Late Cenomanian strata are present only in the Nieuwkerke and tbe Oostduinkerke wens, at some distance south of the crest. Sediments dated as Turonian are found only south of the crest, with a decreasing thickness towards the crest, from the Nieuwkerke to the Keiem well. The Coniacian also occurs only south of the crest, with a similar thickness in the two latter wells. The Santonian bas a similar thickness in the same two wells south of the crest and is present only with a reduced thickness of Late Santonian age in the De Haan and Knokke wells. Campanian sediments occur only north of the crest, in both latter wells. Only Lower Campanian is present in the De Haan well, while a more complete Campanian section, followed by Maastrichtian, is observed more to the north, in the Knokke well. A post-Cretaceous erosion is thought to be responsible for the observed thickness variations in the Campanian north of the cres

Dinoflagellate cysts of the shallow marine Neogene succession in the Kalmthout well, northern Belgium

The dinoflagellate cyst associations from the Neogene succession in the Kalmthout well allow a correlation with biozonations and key dinocyst events from the North Sea area and the eastcoast of the USA. The recovered cyst assemblages suggest that an Early Miocene (late Aquitanian - early Burdigalian) age can be attributed to the Berchem Formation, while the Diest Formation is of Late Miocene (late Tortonian - Messinian) age. The age of the Kattendijk Formation remains unclear. The Lillo Formation in the Kalmthout well is of Pliocene age and possibly not younger than early Late Pliocene

Disused Neogene and Quaternary regional stages from Belgium: Bolderian, Houthalenian, Antwerpian, Diestian, Deurnian, Kasterlian, Kattendijkian, Scaldisian, Poederlian, Merksemian and Flandrian

An overview of eleven disused Neogene regional stages from Belgium is presented. Some of the regional stages were already brought into use in the nineteenth century, but are nowadays considered ill defined and of no use in the light of the modern stratigraphic concepts. An overview of their definition and history is given, together with the argumentation for the abandonment of each unit and its present status. The disused chronostratigraphic units belonged to the Miocene, the Pliocene and the Holocene series

On <i>Prophoca</i> and <i>Leptophoca</i> (Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications

BackgroundProphoca and Leptophoca represent the oldest known genera of phocine seals, dating from the latest early to middle Miocene. Originally, Prophoca rousseaui and Prophoca proxima were described based on fragmentary remains from the Miocene of Belgium. However, several researchers contested the union of Prophoca rousseaui and Prophoca proxima into one genus, without providing evidence. The stratigraphic context of Prophoca remained poorly constrained due to the lack of precise data associated with the original specimens collected in the area of Antwerp (north of Belgium).MethodsProphoca and Leptophoca are redescribed and their phylogenetic position among Phocidae is reassessed using PAUP. Dinoflagellate biostratigraphy has been carried out on sediment samples associated with specimens from Prophoca and Leptophoca to elucidate their approximate ages.ResultsWhereas the species Prophoca rousseaui is redescribed, Prophoca proxima is considered synonymous to Leptophoca lenis, with the proposal of a new combination Leptophoca proxima (Van Beneden, 1877). Sediment samples from specimens of both taxa have been dated to the late Langhian–early Serravallian (middle Miocene). Following a reinvestigation of Leptophoca amphiatlantica, characters from the original diagnosis are questioned and the specimens of Leptophoca amphiatlantica are considered Leptophoca cf. L. proxima. In a phylogenetic analysis, Prophoca rousseaui and Leptophoca proxima constitute early branching stem-phocines.DiscussionLeptophoca proxima from the North Sea Basin is younger than the oldest known find of Leptophoca proxima from North America, which does not contradict the hypothesis that Phocinae originated along the east coast of North America during the late early Miocene, followed by dispersal to Europe shortly after. Morphological features of the appendicular skeleton indicate that Prophoca rousseaui and Leptophoca proxima have archaic locomotory modes, retaining a more prominent use of the fore flipper for aquatic propulsion than extant Phocidae

Stratigraphy of an Early-Middle Miocene sequence near Antwerp in northern Belgium (southern North Sea Basin)

The lithostratigraphy and biostratigraphy of a temporary outcrop in the Antwerp area is described. The deposits can be attributed to the Kiel Sands and the Antwerpen Sands members, both belonging to the Lower and Middle Miocene Berchem Formation. Invertebrate and vertebrate macrofossils are abundantly present. The molluscan fauna compares well to former findings in the Antwerpen Sands Member. It can be concluded that the studied sequence is continuously present in the Antwerp area, and thickens in a northward direction. The study of the marine mammal fauna shows that eurhinodelphinids are the most common fossil odontocete (toothed-bearing cetaceans) in the Antwerpen Sands Member, associated here with kentriodontine, physeteroid, squalodontid, mysticete (baleen whales) and pinniped (seals) fragmentary remains. Both the molluscan fauna and the organic-walled palynomorphs indicate for the Antwerpen Sands Member deposition in a neritic, energetic environment, which shallowed upwards. The dinoflagellate cysts indicate that the Antwerpen Sands Member was deposited during late Burdigalian to Langhian times

Holocene dinoflagellate cysts as salinity indicators from the southwestern Black Sea

Dinoflagellate cysts are used as a proxy for the reconstruction of the salinity variations during Holocene times in the southwestern Black Sea. Core GeoB 7625-2, located 50 km northeast of the mouth of the Sakarya River, was sampled with a 200 year resolution between 0.25 ka BP – 7.8 ka BP. In the lower part of the core, some extra crucial intervals were sampled with a higher resolution for the determination of the reconnection between the Black Sea and the Sea of Marmara. The drastic change in the dinoflagellate cyst assemblage – from a freshbrackish water to saltwater association – is observed between ~9.6 and ~8.1 ka BP, which is earlier than observed in the dinocyst studies of e.g. Marret et al. (in press), Mudie et al. (2001) and Wall & Dale (1973). This could indicate a diachronic salinification of the Black Sea. The fresh to brackish water indicator species are Spiniferites cruciformis form 1-4 and Pyxidinopsis psilata, while the most important saltwater species are Lingulodinium machaerophorum and cysts of Pentapharsodinium dalei. The first occurrence of euryhaline species took place synchronous with a sea level rise and an increase in productivity. The process length of L. machaerophorum, a salinity proxy, indicates a gradual salinity increase. This assumes a gradual reconnection between the Black Sea and the Sea of Marmara, which conflicts with the catastrophic flood (Noah’s Flood Hypothesis) introduced by Ryan et al. (1997, 2003). The 500 to 800 year cycles observed in the sedimentary record by Lamy et al. (2006), and related to the North Atlantic Oscillation, were not only recorded by us in the salinity proxy but also in dinoflagellate cyst abundances (productivity). The observed productivity changes are furthermore related to the sedimentation rate: the increase in precipitation in Anatolia possibly results in a higher sediment discharge leading to a better preservation of the organic-walled microfossils. This makes it difficult to determine whether the fluctuations of the dinocysts/gram ratio are the result of fluctuations in productivity or are an artefact due to changes in the sedimentation rate. Furthermore, it is shown that Peridinium ponticum, a species restricted geographically to the Black Sea, is a good proxy for the reconstruction of Holocene salinity variations since its relative abundance fluctuates synchronous with the process length variations of L. machaeorophorum

Biometry of late Quaternary coccoliths from the Southern Cadiz region

The Cadiz region lies between the Iberian borderland and Morocco, west of the Strait of Gibraltar and the Western Mediterranean. Core GeoB9064-1 (35°24,91’N 6°50,72’W) is located in the southwest at a depth of 702 m, close to the Al Arraich mud volcano field 30 km off the Moroccan margin„ and has a length of 544 cm. Like most coastal regions, the southern Cadiz region is characterised by a coccolith assemblage dominated by the placoliths Emiliania huxleyi and Gephyrocapsa muellerae.Late Quaternary fluctuations are pronounced in this core, as shown by geochemical (TOC and CaC03) and XRF analysis (K, Mg, Fe, etc.), but also in abundances of coccoliths and more particularly Emiliania huxleyi. These can be related to upwelling and/or bottom currents.Colmenero-Hidalgo (2002) has split up Emiliania huxleyi in a larger coldwater and smaller warmwater variety based on a 4 µm cut-off value. Colmenero-Hid algo (2004) identified a deglacial decrease in the larger coldwater variety.In this study, 100 Emiliania huxleyi and 100 Gephyrocapsa muellerae lengths were measured in 30 samples. Comparison of the biometry of Emiliania huxleyi and Gephyrocapsa muellerae shows that these both species have similar fluctuations and both become smaller during the Holocene, revealing the splitting of Emiliania huxleyi in two morphotypes, to be more complex. A new method to tackle this problem is proposed