scholarly journals Stratigraphic correlations between the Brabant Massif and the Stavelot, Rocroi and Givonne inliers (Belgium) and geological implications

2021 ◽  
Vol 24 (3-4) ◽  
pp. 137-157
Author(s):  
Alain HERBOSCH

The Caledonian basement crops out in the middle and southern part of Belgium in two major tectonic units: the Brabant Massif in the Brabant Parautochthon and the Stavelot-Venn, Rocroi, Givonne and Serpont inliers in the Ardenne Allochthon. The main aim of this work is to achieve a chronostratigraphic correlation between the Brabant Massif and the Ardenne inliers, from the lower Cambrian to the Middle Ordovician. Throughout his career, Michel Vanguestaine established an informal acritarch biozonation for this basement, which is only linked to the international stratigraphic scale in vigour at that time. Our first step was to correlate these informal biozones with the trilobite (Cambrian) and graptolite (Ordovician) biozonations which are currently well correlated with the chronostratigraphy. Then, compilation of the literature concerning each of these sedimentary units makes it possible to assign a chronostratigraphic position to their constituent formations. This work has permitted the establishment of a complete chart of the stratigraphic correlations between the Brabant Massif and the three main Ardenne inliers (Stavelot-Venn, Rocroi and Givonne). Geological implications are discussed: the Brabant Massif and the Ardenne inliers formed a single sedimentation basin with different and rheologically contrasting basements (rift and shoulder). New arguments confirm the presence of a Caledonian orogeny in the Ardenne.

The study of samples taken on the bottom of the sea north of the Massif Armoricain, and the geological, magnetic, gravimetric and seismic data collected on land and at sea, confirms that this region is characterized by: (1) a series of horsts where fragments of Pentevrian and Cadomian orogenies outcrops; (2) gullies, or synclines, of Palaeozoic terrain. The separation of the horsts is the result of tectonic shearing which developed during the Ordovician, Carboniferous and Triassic ages. The Cadomian chain, which constituted the fundamental structure of the region, was broken up very early and is no longer recognizable. In the west, traces of this chain seem to have lasted until the Llanvirnian. In the east, the uplands, which were probably less harsh, were levelled before the start of the lower Cambrian age. A general upwarp of the eastern part between the middle Cambrian and the middle Ordovician could correspond to a reaction to the Caledonian orogeny. The northern part of the Alassif Armoricain had little part in the Hercynian paroxysm, however, this period witnessed an important tangential tectonism, the horsts riding over the edges of the synclines. The western formations show more marked structures than the eastern formations. The area which has been studied largely corresponds to the Domnonean domain, a puzzle of horsts and grabens. The Domnonea is itself a large horst, limited to the north by thick Palaeozoic sequences and to the south by the central Armorican zone and the Mancellian domain.


1992 ◽  
Vol 129 (5) ◽  
pp. 513-514
Author(s):  
N. H. Woodcock ◽  
C. J. N. Fletcher

The Welsh Basin was an area of enhanced Early Palaeozoic subsidence on the northwestern margin of the Eastern Avalonian microcontinent. It is bordered to the southeast by the Midland Platform and to the northwest by the smaller Irish Sea Platform (Fig. 1). The sedimentary rocks of the basin and its flanking platforms range from Lower Cambrian through Lower Devonian. The sequence is dominantly marine, with abundant volcanics in the Ordovician. A basinwide change to non-marine facies is preserved in the Lower Devonian, heralding basin inversion and the culminating Acadian (late Caledonian) Orogeny.


1981 ◽  
Vol 18 (5) ◽  
pp. 972-980 ◽  
Author(s):  
David R. Kobluk

In the Lower Cambrian Forteau Formation (middle Bonnia–Olenellus zone) of southern Labrador, cavities in archaeocyath patch reefs contain preserved coelobiontic endolithic sponges. Scallops and carbonate chips produced by sponge boring, spicules, and preserved endolithic sponge body fossils all point to the presence of endolithic sponges in Lower Cambrian reef cavities.The oldest previously described endolithic sponges are Early Ordovician in age and the oldest previously known reef interior bioerosion is Middle Ordovician in age. The presence of endolithic sponges in reef cavities of the Forteau Formation therefore extends both the record of endolithic sponges and of reef interior bioerosion from the Ordovician to the upper Lower Cambrian.


1984 ◽  
Vol 121 ◽  
pp. 19-51
Author(s):  
P.R Dawes ◽  
J.S Peel

Sections and fossil collections resulting from activities under Operation Grant Land 1965-66 in the Hall Land - Wulff Land region of western North Greenland are briefly discussed. Strongly tectonised Lower Cambrian to Silurian strata are present in the northern part of the area in association with the Wulff Land anticline and the Nyeboe Land fault zone. To the south, platform and deep-water trough sequences are generally little disturbed and strata range in age from Middle Ordovician to Late Silurian (Pridoli). Most stratigraphic units can be accommodated in stratigraphic schemes established in Washington Land, to the west, or Peary Land, to the east.


1977 ◽  
Vol 82 ◽  
pp. 1-48
Author(s):  
R.L Christie ◽  
J.S Peel

A sequence of Lower Palaeozoic carbonate and clastic rocks is described from Børglum Elv, Peary Land, eastem North Greenland, and briefly compared to Lower Palaeozoic sections elsewhere in Greenland and in Spitsbergen. Lower Cambrian clastic rocks of the Buen Formation are followed by dolomite of the Lower Cambrian Brønlund Fjord Formation (125 m). Succeeding dolomite and dolomitic limestone of the Wandel Valley Formation (320 m) of Early to Middle Ordovician age are overlain by limestone of the Børglum River Formation (430 m) of Middle to Late Ordovician age. Un-narned Early Silurian dolomite and limestone formations (150 m and 320 m respectively) are followed by an un.narned Middle Silurian black shale formation (c. 100 m) and at least 800 m of a late Middle Silurian and younger un-named flysch formation. Carbonate mounds, originating in the highest beds of the un-named Silurian limestone formation, occupy stratigraphic levels through the overlying black shale formation and into the flysch formation.


1968 ◽  
Vol 5 (3) ◽  
pp. 501-513 ◽  
Author(s):  
M. F. Tuke

Rocks outcropping in the northernmost part of the island of Newfoundland belong to two sequences, which are partly contemporaneous and very different in lithology. One sequence consists of Lower Cambrian sandstones and Lower and Middle Ordovician carbonates and shales. The other sequence consists of graywackes, volcanic rocks, and ultrabasic intrusions, which are, in part, early Ordovician. This latter sequence is interpreted as allochthonous because it is underlain by major low-angle faults and because of its strong facies contrast with the first sequence. The allochthonous rocks occur in three separate klippen.The trend of slickensides, attitude of folds, and deflection of beds at fault surfaces all indicate that movement along the low-angle faults that underlie the klippen was to the northwest. The klippen probably originated from an area 60 km to the southeast, which is on strike with similar rocks in north-central Newfoundland.It is suggested that the klippen moved by gravity sliding in late Middle Ordovician time.


Author(s):  
Terence P. Fletcher ◽  
Adrian W. A. Rushton

ABSTRACTDark limestones in the old quarries at Leny, Perthshire contain sparse beds with tiny fossils. They are poorly preserved and, though barely affected by the Ordovician Grampian Event tectonism, there is some taphonomic distortion and many are corroded along stylolitised horizons. The fauna mainly comprises trilobites of two types, open-ocean miomerids and polymerid shelf dwellers. MiomeridsCondylopygecf.eliandKiskinella cristataindicate a stratigraphical position equivalent to the base of the paradoxidid Amgan Stage of Siberia; traditionally regarded as ‘Middle Cambrian’. However, the bulk of the Leny miomerids, notably species ofPagetides, are forms described from the outer edge of Laurentia, within theBonnia–OlenellusZone, where it is considered to be ‘Lower Cambrian’. The Leny polymerids were likely transported off-shelf and some are conspecific with taxa in the Laurentian allochthonous Quebec and New York successions of the Early–Middle Ordovician (Taconic) Appalachian Orogen. The Leny Limestone and Shale Member of the Keltie Water Grit Formation is part of the Dalradian Supergroup deposited in an off-shelf Caledonide Grampian Terrane of the Humber Tectonostratigraphical Zone, midway between the North American successions and the Greenland Caledonides.Additional to the trilobites, brachiopods, sponges, hyoliths, bradoriids and a selection of indeterminable organic fragments occur; none of which has any particular age significance.


1993 ◽  
Vol 67 (5) ◽  
pp. 788-798 ◽  
Author(s):  
Jin Yugan ◽  
Hou Xianguang ◽  
Wang Huayu

The vermiform pedicle is one of the most distinctive organs of modern lingulids, but it is rarely preserved. Only two fossil specimens of lingulids with pedicle casts have been reported, one from the Ordovician and the other from the Devonian. No record of fossil pedicles of Lingulella and Lingulepis, the dominant Cambrian and Early Ordovician lingulids, is known. Fossil lingulids from the Lower Cambrian of Chengjiang County, Yunnan, suggest that the structure and function of the pedicle of the lingulids has not changed significantly from its first appearance. A comparison of fossil pedicle of lingulids from the Lower Cambrian, Chengjiang County (China), the Burgess Shale, Middle Cambrian, British Columbia (Canada), the Trenton Formation, Middle Ordovician, New York (U.S.A.), and the Devonian, Devonshire (England, U.K.) shows that the delthyrial area to which the pedicle muscles are attached was reduced in length through time until these muscles were completely embraced by the two valves.Two species, Lingulella chengjiangensis n. sp. and Lingulepis malongensis Rong, are described.


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