Mohamed Soussi

Dinosaurs and other fossil vertebrates from fluvial deposits in the Lower Cretaceous of southern Tunisia

Remains of dinosaurs and other vertebrates (sharks, bony fishes, coelacanths, turtles, crocodilians, pterosaurs) are reported from the Chenini Formation of the Tataouine region in southern Tunisia. The Formation is part of the ‘continental intercalaire’, a succession of continental deposits of Early to Late Cretaceous age distributed over the whole of North Africa and the Sahara. It consists of bar and channel deposits of broad rivers that flowed NNW from the mid-Sahara region towards the southern shore of Tethys. Dinosaur-bearing units in the ‘continental intercalaire’ have been dated to the Hauterivian to Cenomanian, and the Chenini Formation is possibly Albian in age. Dinosaur fossils include abundant teeth of the theropods Carcharodontosaurus and Spinosaurus, as well as postcranial elements of theropods and a medium-sized sauropod. A tooth of an ornithocheirid is the first report of a pterosaur from the region. The dinosaur bones and teeth were transported some distance and deposited in a channel lag, associated with less damaged locally derived material such as fern fronds, coprolites, fish teeth and scales, and crocodilian scutes.

A record of the Jurassic/Cretaceous boundary climatic variation on the southern margin of the Tethys : clay minerals and palynofacies of the early Cretaceous Jebel Meloussi section (Central Tunisia, Sidi Kralif Formation)

In order to precise the paleogeographic extension of the climatic variation known at the Jurassic/Cretaceous boundary, the sedimentary organic matter (palynofacies and Rock-Eval) and the clay minerals content of Berriasian sediments of the Sidi Kralif Formation are studied on the Jebel Meloussi section, central Tunisia. Standard sedimentological and palynofacies analysis allow to reconstruct the bathymetric curve and the sequence stratigraphic scheme. Using existing biostratigraphy based on calpionellids and ammonite zonation, the sequence stratigraphic interpretation can be correlated with the established eustatic chart. Clay mineral assemblages are characterized by a shift in the kaolinite content, recorded at the end of the calpionellid zone B, at the early/middle Berriasian boundary, at a time of high long-term sea-level (MFS Be2, second order eustatic peak). A contemporary change in the clay mineral assemblages, interpreted as a climatic change, is known from the boreal area, and from the northern margin of the Tethys Sea. That change is also documented southerly in southern Morocco (Agadir area), on the Atlantic domain. A late Tithonian to early Berriasian dry and cooler phase is replaced by a middle to late Berriasian more humid phase, indicated by a general increase in kaolinite in the clay mineral assemblages. The trend from a dry climatic phase to a more humid one, recorded on the boreal domain and along the northern margin of the Tethys is also recorded in lower paleolatitudes of Tunisia, on the southern margin of the Tethys, in better dated outcrops than the ones of Morocco. The results obtained in Tunisia show that the beginning of the climatic change was precisely synchronous on both margins, and occurred within the same long-term high sea-level context.

Early Bartonian orthophragminids (Foraminiferida) from Reineche Limestone, north African platform, Tunisia: taxonomy and paleobiogeographic implications

The orthophragminids in lower Bartonian Reineche Limestone member, a fossiliferous shallow-marine unit exposed in Cap Bon peninsula in Tunisia, are represented by 17 species assigned to Discocyclinidae Galloway 1928 and Orbitoclypeidae Brönnimann 1946. These taxa, associated with nummulitids and alveolinids, belong to the lineages of Discocyclina Gümbel 1870, Nemkovella, 1987, Orbitoclypeus Silvestri 1907, and Asterocyclina Gümbel 1870, described for the first time from north Africa lying at the southern margin of Tethyan ocean during Paleogene. We identified Nemkovella evae, previously not recorded in upper Lutetian/lower Bartonian and younger Eocene deposits of northern Tethyan platforms, and erected a new subspecies, N. evae reinechensis n. ssp. A comparison of Reineche orthophraminids, assigned to orthophragmines zone (OZ) 12 and shallow benthic zone (SBZ 17), to the well-described coeval assemblages at northern Tethyan platforms in Italy, Hungary, Turkey, and to those in Kutch Basin in the Indian subcontinent suggests that some species are confined to certain paleogeographic domains. Orbitoclypeus haynesi, the only orbitoclypeid and the most abundant orthophragminid in lower Bartonian deposits in Kutch, appears to be the most common orbitoclypeid in Reineche Limestone. In Europe, this species is not known and is replaced by Orbitoclypeus varians, the most common orbitoclypeid in middle Eocene of central Europe. Both species occur in varying proportions in marine successions in Turkey. Asterocyclina sireli, identified so far only in Turkey, occurs in Reineche Limestone and in lower Bartonian deposits in Kutch. This species is recorded for the first time in the Indian subcontinent. Relying on present study, as well as our recent studies in Kutch Basin, we conclude that the generic and specific diversity of orthophragminids decreases eastward from the peri-Mediterranean region to Indian subcontinent and to the western Pacific.

Integrated biostratigraphy and regional correlations of Upper Jurassic–lowermost Cretaceous series in northern Tunisia

Integrated biostratigraphy and palaeogeographical interpretations of Upper Jurassic–Lower Cretaceous (Callovian–Berriasian) successions are synthesised on the basis of published data and our recent investigations of key sections from the “Tunisian Dorasale” (TD) and “Tunisian Trough” (TT) domains of northern Tunisia. After a revised biostratigraphy had been proposed for the “rosso ammonitico” series, bed-by-bed sampling led to a radiolarian-based first direct dating of the partly coeval biosiliceous series in the TT. Upward within the Jurassic column, an integrated biostratigraphy (ammonites, calpionellids and associated biomicrofacies) allowed precise biozonation for the Kimmeridgian–middle Berriasian interval. The heterogeneity of the Late Jurassic facies in northern Tunisia is the result of two main geodynamical and palaeogeographical events. The first corresponds to the fragmentation of the initial Early Jurassic platform linked to Tethyan rifting. The second event, coeval to the radiolarian-bearing series of the TT, is expressed by a significant deepening in north-west Tunisian palaeoenvironments. During Kimmeridgian–Tithonian times, previous troughs evolved back into carbonate platforms. Within the Maghrebian Belt, Upper Jurassic–lowermost Cretaceous series comprising three major facies groups are easily correlated; minor differences in age are interpreted as due to local tectonic control. Regional correlations confirm, on the one hand, a common geological history for the external segments of the African margin and, on the other hand, a distinct palaeogeographical evolution of the inner domain including the “Dorsales calcaires” and ancient massifs, both being separated by intermediate flysch zone segments.

Integrated gravity and seismic investigations over the Jebel Es Souda-Hmaeima structure: implication for basement configuration of the eastern frontal fold-and-thrust belt of Tunisian Atlasic Mountains

A gravity and seismic analysis was conducted over and around Jebel Es Souda-Hmaeima, located on the eastern border of the Tunisian Mountains between the Atlasic block to the west and the Pelagian Block to the east, as part of a study to investigate the subsurface structures. These data, together with outcrop geology, well data, and measurements of physical properties of rock samples, were integrated with a new interpretation of the tectonic model of Jebel Es Souda-Hmaeima anticline. This structure represents a backfolded anticline associated with a steep east-vergent thrust above a blind thrust fault along the base of Triassic formations. The proposed model emphasizes the role of transpressional deformation along deep-seated basement faults and has implications for petroleum generation, migration, and entrapment in central Tunisia.تم تطبيق قيس شاذات بوجيه وقيس الذبذبات السيسميكية لدراسة تركيبة جبل لسودة – حميمة ، الواقع بالجبال الشرقية التونسية بين المنطقة الأطلسية والمنطقة البلاجية الساحلية.مكننا تحليل شاذات بوجيه والمقاطع السيسميكية ، إضافة إلى المعطيات الخاصة بالجيولوجيا السطحية والآبار العميقة والخصائص البتروفيزيائية للأحجار ، من تحديد تفسير جديد للأنموذج التكتونيكي لجبل لسودة –حميمة.هذا الأنموذج الجديد يبرز أهمية التركيبة المتصلة بتحركات الفوالق وبالخصائص البتروفيزيائية للأحجار الترياسية كما يحدد مدى تأثيراتها على تكوين ، تنقل وخزن الموارد البترولية.

Cypridea Bosquet, 1852 (Ostracoda) in the Early Albian of Tunisia

Fig. 1 Cypridea gr. laevigata (Dunker, 1946), sample K6, Early Albian, Jebel Kebar. 1, carapace, right lateral view, specimen J. Keb. 0001 (L = 1.0 mm). 2, carapace, right lateral view, specimen J. Keb. 0002 (L = 1.1 mm). The sub-cosmopolitan limnic ostracod genus Cypridea Bosquet, 1852 ( sensu Horne & Colin, 2005) is known from the Lower Tithonian (Martin-Closas et al ., 2008) to the Aptian, with a maximum development during the Berriasian to Barremian (Horne, 1995), in Europe, Africa, the Middle East, North and South America. In the Far East (China, Mongolia) and Alaska it ranges up to the Cretaceous–Tertiary boundary (Brouwers & De Deckker, 1993; …

Groundwater investigation in the southern part of Gabes using resistivity sounding, southern Tunisia

The groundwater hydrogeology of southern Tunisia emphasizes two main groundwater bodies so-called Zeuss-Koutine and south Gabes. These groundwater bodies yielding economically important storage of useful water present complex internal architecture and heterogeneity allowing exchange flows throughout permeable or/and fractured bodies. A geophysical survey using resistivity soundings was carried out along this area to describe in detail the field structure and the 3D extent of these groundwater bodies by the hydrogeological new data and detailed subsurface mapping based on resistivity sounding and seismic data. This survey discusses also the potentialities of some permeable layer in water storage and purposes potential favorable areas for optimum groundwater mining.

The Numidian Flysch Complex of Onshore Tunisia (Southern Kroumirie Range) - Facies Analysis and Stratigraphic Review

Sedimentological analysis and biostratigraphic review of the Oligo-Miocene deposits of northern Tunisia provide new data allowing new stratigraphic and paleogeographic reconstruction. The Kroumirie and Zouza member have the same age and correspond to sand/mud and mud/sand rich systems of a deep sea fan system with a detrital influx supplied from the North. Structural analysis demonstrate that the Numidian flysch has been displaced by a major thrust fault.

The Onshore Tunisia Numidian Flysch

The study concerns the Oligo-Miocene aged Numidian Flysch which forms the highest structural unit in northern Tunisia and consists of an interbedded unit of highly quartzose sand and shale, which are of turbiditic affinities. An integrated petrographic and geochemical study of this formation was carried out to infer the sandstones provenance, and reservoir characteristics. On the basis of the framework composition (point counting) and whole-rock geochemistry (major elements), the sandstones are classified as quartzarenite, and sublitharenite types. The modal analyses imply a recycled orogen provenance. Moreover, petrographic point count data indicate quartz-rich sedimentary (recycled), middle to high-grade metamorphic and plutonic parent rocks for Numidian sandstones. According to the plate and tectonic reconstructions of the western Mediterranean Sea it appears that the kabylean basement terrain cropping out along the Algerian coast and forming part of Calabro-Peloritani-Kabylian zone to be the parental source of the Numidian of both Sicily and Tunisia. Additionally, petrographical study indicates that the reservoir properties of the Numidian Flysch are a direct function of grain size and textural maturity.

Limulitella tejraensis, a new species of limulid (Chelicerata, Xiphosura) from the Middle Triassic of southern Tunisia (Saharan Platform)

Abstract. Numerous well-preserved remains of a new limulid species from the Anisian-lower Ladinian (Middle Triassic) of the Tejra section of southern Tunisia are described. Comparisons are made with limulids from the Triassic deposits of Europe and Australia. The new specimens are congeneric with the type species of Limulitella, but show some morphological differences. Here we describe Limulitella tejraensis new species, a small limulid with semicircular prosoma, small and triangular opisthosoma, well-defined axial ridge, and pleurae along both ridges of the opisthosoma. The Tunisian Limulitella fossils are associated with conchostracans, bivalves, gastropods, and microconchids. Sedimentological and paleontological data from the Tejra section suggest freshwater to brackishwater conditions during the formation of the fossil-bearing interval and the influence of marine transgression into a playa-like environment. Supposed adaptation to the stressful environment sheds new light on the origin and survival of the extant limulines. This is the first report of limulid body fossils from the Triassic of North Africa and the first documentation of Limulitella in the Middle Triassic of northern Gondwanaland.