Sedimentary environments, conodont biofacies and paleoecology of the belgian Famennian (upper devonian) - an approach

The vertical succession of the sedimentary formations, which are diachronic with respect to the standard conodont and other microfossils zonation, represents a regressive megasequence in the Belgian Famennian, ranging from relatively deep, offshore open marine, shallow nearshore, to backshore restricted marine environments (THOREZ et al., 1977). Different associations of platform conodont form genera (Biofacies) reflect different ecological conditions, which are directly or indirectly related to water depth, turbulency, salinity and proximity to the coast ; from offshore to backshore we recognized successively a Palmatolepid, a Palmatolepid-Polygnathid, a Polygnathid-Icriodid, an Icriodid, and a supposed Clydagnathid biofacies. In this way the distribution pattern of conodont biofacies throughout the Famennian, represents a normal response to the oscillating movements of a prograding "coast" in the studied sedimentary basins. The presence moreover of mixed conodont biofacies (or thanatocoenoses) is also related to sedimentological processes, such as storm wave action, turbidity currents and tidal inlets

Fammenian

The name of the Famennian stage originated in the 19th century from the Famenne region in southern Belgium. After the pioneering work of Dumont, d'Omalius d'Halloy, Gosselet and Mourlon, a renewed interest in the 1960’s focused mainly on the lithological, sedimentological, paleontological and palynological characteristics of the Famennian. This resulted in a refined litho- and biostratigraphical framework for the Lower Famennian Famenne Shales and the Upper Famennian Condroz Sandstones in Belgium. The most obvious finding was the distinct diachronous character of the Condroz Group. The present review paper extends this stratigraphical framework into the neighbouring Avesnois (Northern France) and Aachen (Northwestern Germany) areas: it proposes a lithostratigraphical correlation between the units identified within the individual tectonic units. An overview is given of the main lithological-sedimentological characteristics, depositional environments (for both the siliciclastics and the carbonates) and prevailing paleogeographical-paloeclimatological conditions, during the Famennian stage in Belgium and adjacent areas

Archiving Complex Digital Artworks

The transmission of the documentation of changes made in each presentation of an artwork and the motivation behind each display are of importance to the continued preservation, re-exhibition and future understanding of artworks. However, it is generally acknowledged that existing digital archiving and documentation systems used by many museums are not suitable for complex digital artworks. Looking for an approach that can easily be adjusted, shared and adopted by others, this article focusses on open-source alternatives that also enable collaborative working to facilitate the sharing and changing of information. As an interdisciplinary team of conservators, researchers, artists and programmers, the authors set out to explore and compare the functionalities of two systems featuring version control: MediaWiki and Git. We reflect on their technical details, virtues and shortcomings for archiving complex digital artworks, while looking at the potential they offer for collaborative workflows

The petrography and origin of deposits filling solution pipes in the Chalk near South Mimms, Hertfordshire

RESP-648

La formation d'Herzeele: un nouveau stratotype du pleistocene moyen marin de la mer du Nord

The Herzeele Brickyard (Northern France) offers a permanently well exposed outcrop of continental and marine deposits which are reaching a total thickness of 6 m and are overlying the Ypresian clay of eocene age, occuring at about 8 m N.G.F.Three marine phases represented by tidal flat and brackish sediments may be readily distinguished. The tidal flat sediments have previously been recognized in the area of Izenberge (Belgium) from which locality the name "Izenberge Cardium Sands" has been derived. The marine sediments may be subdivised into units of different lithology: the lower sandy unit, the middle loamy-clayey unit and the upper sandy clayey unit which latter is characterized by the abundance of Cardium edule and Macoma balthica. The marine phases are furthermore separated by continental deposits amongst which peat layers are occurring. The cover sediments are represented by eolian sands and loams interfering with palaeosoils. The series of sediments underlying these cover deposits is named the "Herzeele Formation" which represents a lithostratigraphical unit in the southern North Sea basin. The analysis of the heavy mineral content points to a change in sediment origin occuring after the lower marine sedimentation. The middle and upper marine units contain an increasing content of green hornblende and epidote. Some volcanic minerals were observed at different levels. The clay analyses by means of X-ray diffraction indicate that the different lithostratigraphical units bear polymineralic clay assemblages within which the smectitic fraction is predominant. Greene-Kelly's (1953) Li-test yielded a further detailed analysis of the smectitic components: beidellite, montmorillonite-like. minerals as well as random mixed-layers illite-smectites. The analysis indicates a stratigraphical - mineralogical subdivision of the section which coincides with the lithostratigraphical one.The pollen analytical data show that the whole of the Herzeele Formation most probably belongs to the second half of the Holsteinian interglacial, except for the very base composed of glauconiferous sands. It may readily be seen that the forest evolved from a mesocratic phase, characterized by a Quercetum mixtum with Picea, towards a telocratic phase during which the forest became dominated by Abies. Within the peat which is resting upon the glauconiferous sands, the pollen grains of Taxus, are very abundant in the overlying clay however, this species declines gradually and disappears at the top of the upper marine unit. These evidences are corresponding with the first half of the so-called Abies- zone. Buxus and Vitis, both undergo the same evolution. The only Tertiary relict, Pterocarya, made a short appearance at the top of the upper marine unit, while Azolla filiculoides, was only discovered in the Quercetum zone. The diatom analyses indicate the conditions of brackish and marine sedimentation in a tidal environment. Although the magnetostratigraphical approach of deep-sea and lake sediments has proven to be successful, its application to continental and especially coastal sediments is hampered by the very nature of these sediments (large variation of sedimentation rate, depositional environment, lithology, a.o.) The palaeomagnetical study of the Herzeele Formation reveals a striking difference inmagnetic behaviour between the upper and lower beds separated by the lowermost peat layer. The upper beds are characterized by a strong dispersion of the magnetisation directions and a low intensity. Therefore identification of clear-cut magnetozone(s) is not possible for the moment being. As to the extension of the Herzeele Formation in Belgium, it was only found south of the river Yzer. The comparison with the area of Izenberge itself did not reveal any lithostratigraphical correlation with the Herzeele Formation. The situation of the stratum (former shoreline) at this type-locality gives prove of the importance of the palaeographical evolution since the Lower Pleistocene with the formation of the southern North Sea basin and probably the early opening of the Strait of Dover as well. Therefore this stratum is considered as a landmark and a witness of several interglacial marine transgressions which are attributed to the Holsteinian and to the upper part of the "Cromerian complex"

Arctic shipping and polar seaways

Climate change in the Arctic triggered a series of discourses about the opening-up of a previously unreachable region. Navigation remains however difficult in the Arctic, transits are still very limited, as sea-ice still is a major constraint. How did the development policies of both the North West Passage and the Northern Sea Route unfold ? What are the recent trends in Arctic shipping ?