Southern Margin Of Tethys Research Articles

Glabrobournonia Morris and Skelton (Rudist, Bivalvia) from the Campanian–Maastrichtian of Türkiye: Taxonomy, palaeoecology and palaeobiogeography

A re-examination of the specimens described as Bournonia anatolica Özer and Bournonia sp. from central and southeastern Anatolia, Türkiye reveals that they have diagnostic characteristics of the genus Glabrobournonia Morris and Skelton. New rudist material from the middle Campanian to late Maastrichtian mixed siliciclastic-carbonate sequences in the Sakarya Zone (Eastern and Central Pontides), in the east of the Anatolid–Tauride Block and in southeastern Anatolia (north of the Arabian Platform) in Türkiye also showed the occurrence of Glabrobournonia anatolica (Özer) and Glabrobournonia arabica Morris and Skelton. Glabrobournonia anatolica is characterised by a large, rectangular right valve with pronounced growth lamellae, a salient ventral carina and interband, a less salient dorsal carina, a concave indentation anterior band, a slightly concave posterior band and broad and smooth anterior surface as well as the absence of radial ribbing and ligamentary infolding. Glabrobournonia arabica has the diagnostic features of the species, such as small valves, conical right valves with a smooth surface, ventral and dorsal carinae and two concave indentations of anterior and posterior bands separated by an interband. The palaeoecological characteristics of these lateral clinger morphotypes are presented according to growth geometries. For the cosmopolitan genus Glabrobournonia, two main migration routes have been proposed for the Campanian–Maastrichtian time: one along the southern margin of the Tethys from the United Arab Emirates–Oman border region to the Zagros (Iran) and southeastern Anatolia, connecting to the northern margin of the Tethys to the Anatolid–Tauride Block and the Sakarya Zone in Türkiye, and another from the United Arab Emirates–Oman border region to the Zagros Zone (Iran) and the Tarim Basin, connecting the northern and southern margins of the eastern Tethys.

Crinoids from the Ouarsenis Massif (Algeria) fill the Lower Cretaceous (Berriasian and Valanginian) gap of northern Africa

The Ouarsenis Massif belongs to the Algerian Tell domain, which is considered as the eastern part of the Maghrebian Tethys former margin. The Berriasian-Valanginian Oued Fodda Formation outcropping in the Kef Aïn El Hadjela section, at the foot of the great peak of the Ouarsenis Massif, is composed of marls and laminated and bioturbated limestone alternations. The marl facies reveals diverse microfauna, including crinoids. These latter are represented by: Isocrinida [isocrinids Balanocrinus cf. gillieroni (de Loriol), Percevalicrinus aldingeri Klikushin, Isocrinus? lissajouxi (de Loriol)], Cyrtocrinida [cyrtocrinids (Phyllocrinus sp., Hemibrachiocrinus sp.)], and Roveacrinida gen. indet. sp. indet. [roveacrinids]. All these, with exception of roveacrinids and phyllocrinids, are noted for the first time from Algeria and African continent (southern margin of Tethys in the Maghreb). Knowledge on Cretaceous crinoids formerly described from Algeria is presented. It is also shown that crinoid assemblage and associated invertebrates are typical for relatively shallow, distal depositional setting situated below storm wave base.

3D- Seismic Analysis of Paleocene Carbonate Succession in Nafoora Area, Southeast Sirt Basin, Libya

This paper focuses on seismic interpretation of Paleocene sequence in Nafoora area. Composite logs, check shots and sonic logs for many wells in the block 51W have been used herein. The paper aimed to i) present time structural maps for each unit to demonstrate their lateral distribution throughout the area of study, ii) and to evaluate the relation between the stratigraphy and structural setting across the Nafoora Fault. The maps are generated for Arish and Harach horizons on basis of 3D seismic data, and formation tops. Variations in lithology, and the development of faults, which introduce discontinuities in the reflectors mostly control the continuity of the seismic events. The fault patterns show that most of faults are of normal type with a NW-SE strike trend, these faults generally coincide with the major regional structural features in the eastern Sirt Basin. However, this study provides an opportunity to examine deposition and the stratigraphy of the carbonate platform on the southern margin of Tethys during the Paleocene. Furthermore, the work may have economic benefits to the petroleum industry in form of a predictive tool for future locations of hydrocarbon prospectivity.

Polyonyx-like tracks from Middle-?Upper Jurassic red beds of Morocco: Implications for sauropod communities on southern margins of tethys

A new dinosaur tracksite is reported from continental red beds of the Jurassic (Late Bathonian-?Callovian) Isli Formation along the northern flank of the Aït Ali ou Ikkou Syncline of the Imilchil area, Central High Atlas, Morocco. The succession was deposited in a fluvio-lacustrine environment, and contains at least fourteen track-bearing levels. The diverse dinosaur-dominated ichnofauna includes the footprints of crocodylomorphs, pterosaurs, theropods, sauropods and ornithischians, together with numerous invertebrate traces. Here, we focus on a long sauropod trackway, which comprises nine consecutive manus-pes sets preserved as concave epireliefs. The low heteropody and asymmetry of manus prints with a large digit I (pollex) impression oriented medially, and a large triangular claw trace, which is posteriorly oriented, are characteristic of the ichnogenus Polyonyx. Different from typical Polyonyx is the narrow gauge pattern compared to the wide gauge observed in the type trackway from Portugal. Additional material from Morocco, similar to Polyonyx, comprises the trackway of a very small (?juvenile) individual found close to the main trackway, as well as a short trackway from a different locality in the Isli Formation. Our data from the Moroccan High Atlas indicates the presence of basal eusauropods in the Middle Jurassic-Early Cretaceous interval in the northwestern part of Gondwana for the first time, and suggests they inhabited a lacustrine paleoenvironment.

Osteology of Eubiodectes libanicus (Pictet & Humbert, 1866) and some other ichthyodectiformes (Teleostei): phylogenetic implications

The osteology of the ichthyodectiform Eubiodectes libanicus (Pictet & Humbert, 1866) from the Cenomanian of Lebanon is described on the basis of acid-prepared specimens. For comparative purposes, the osteology of other putative ichthyodectiforms is described or discussed. We focus on the description of hitherto poorly described species such as Chiromystus mawsoni Cope, 1885, Ghrisichthys bardacki (Cavin, 1997a), ‘Saurodon' intermedius (Newton, 1878) and Thrissops sp. from Kimmeridge, England. Sixty-nine morphological characters are defined and analysed to infer the phylogenetic relationships within ichthyodectiforms. The main results are: (1) exclusion of Ascalabothrissops and Pachythrissops from the ichthyodectiforms; (2) redesignation of ‘Ichthyodectes' bardacki, from the Turonian of Morocco, to Ghrisichthys gen. nov.; (3) resolution of a monophyletic family Cladocyclidae grouping mid-Cretaceous ichthyodectiforms that lived mainly along the southern margin of Tethys (Chirocentrites, Cladocyclus, Eubiodectes, Chiromystus); (4) resolution of a Late Cretaceous family Ichthyodectidae containing Ichthyodectes, Ghrisichthys and Xiphactinus from mid-northern latitude seas; and (5) a better resolved Late Cretaceous family Saurodontidae in the northern hemisphere, that includes the genus Gillicus.

Paleocene depositional environments and depositional sequences in the Dababiya Quarry Corehole (Egypt)

The Paleocene interval of the Dababiya Quarry Corehole (DQC) (at Dababiya, near Luxor, Egypt) comprises mainly hemipelagic sediments (calcareous claystone, marl and chalk), deposited in outer neritic to upper bathyal environments on the southern margin of Tethys. The earliest Danian is however represented by dark gray claystone deposited in shallower, mid neritic environments. The greatest water depths were reached in the mid-Thanetian.n The principles of identifying sequences and sequence tracts in hemipelagic settings are summarised. Nine depositional sequences are tentatively differentiated at Dababiya, based mainly on sedimentology, gamma-ray and magnetic susceptibility logs and foraminiferid assemblages. Comparisons are made with depositional sequences differentiated in other low and mid-latitude areas.

Paleoenvironments of the latest Cretaceous oil shale sequence, Southern Tethys, Israel, as an integral part of the prevailing upwelling system

The Late Cretaceous succession in Israel is part of an extensive high-productivity upwelling regime that persisted over ~ 20 m.y. in the southern margins of Tethys. The deposition of a ~ 40-m thick organic-rich carbonate (“oil shale”) sequence in the Negev, Israel, indicates a major change in the evolution of this high-productivity regime and reorganization of the marine ecosystem during the latest Campanian–early Maastrichtian time. The main objective of this study was to reconstruct changes in surface water productivity and seafloor oxygenation during the deposition of the Oil Shale Member (OSM) and transitions with the underlying Phosphate and overlying Marl Members using high-resolution records of planktic and benthic foraminifera and total organic carbon (TOC) content. The updated age of the OSM, determined by integrating planktic foraminifera, calcareous nannofossils and inoceramids, suggests that this sequence spans a maximum of 1.85 m.y. from 71.6 to 69.85 Ma, with a sedimentation rate of at least 2.4 cm/kyr. Five distinct planktic (P-Types) and benthic (B-Type) foraminiferal assemblages were distinguished in the studied sequence. The change from P-Type 5 to P-Type 1 along the sequence correlates with a distinct decrease in TOC content (18.0–0.1 wt.%), and signifies an upward decline in surface productivity. Based on this relationship, it was inferred that species of Globigerinelloides (principally Globigerinelloides asper) are the best tracers for extreme eutrophic surface water, whereas heterohelicids are associated with more mesotrophic conditions. The transition in time from assemblages B-Types 5 to 1 mainly reflects a change from the predominance of praebuliminids and neobuliminids to a more diversified rotaliid-dominated assemblage, indicating an increase in bottom water aeration. The appearances of planktic foraminifera coincident with the establishment of benthic rotaliid fauna at the Phosphate-Oil Shale Member transition mark the most prominent change in the upwelling sequence. This change probably reflects moderate weakening of the eutrophic surface water productivity and a regional sea level rise resulting in seafloor deepening and improved seafloor aeration. A further step in the decrease in TOC content (to 5.5–8 wt.%) occurs in the uppermost part of the OSM (latest Campanian) and corresponds to the transitions to assemblages P-Type 1 and B-Type 1. This change suggests a shift to mesotrophic conditions, additional increase in bottom and pore water aeration, and thus the demise of the upwelling activity in the southern Tethys.

First evidence of stegosaurianDeltapodusfootprints in North Africa (Iouaridène Formation, Upper Jurassic, Morocco)

Abstract: New findings of dinosaur footprints are described from the Upper Jurassic Iouaridène ichnosite of Morocco. On the top of two surfaces, stratigraphically close to that bearing the famous Breviparopus taghbaloutensis trackways, two footprints were excavated and assigned to the ichnogenus Deltapodus. This ichnogenus is well known from the Middle Jurassic of Yorkshire and also occurs in Upper Jurassic deposits from Iberia and the United States. This finding represents the first record of Deltapodus from Africa. These footprints, probably produced by stegosaurian dinosaurs, add new data on the distribution of this type of dinosaur and on the connection between the northern and southern margin of Tethys. 3D models have been generated to allow more detailed studies and to record these unique footprints.

Early Jurassic (Pliensbachian-Toarcian) Dinoflagellate Migrations and Cyst Paleoecology in the Boreal and Tethyan Realms

The discrepancies in the stratigraphical ranges of selected dinoflagellate cysts recorded in the Boreal and Tethyan realms have revealed two migrational events during the Early Jurassic. The first event occurred at the early-late Pliensbachian boundary and consists of mutual biotic exchanges between the two realms. This is linked to a major Early Jurassic transgression which improved marine communications between the Boreal and Tethyan areas. The second dinoflagellate migrational event occurred during the mid Toarcian and was driven by paleoenvironmental factors. The numerous available Lower Jurassic dinoflagellate cyst data from the Boreal and Tethyan realms indicates that phytoplankton distribution was profoundly affected by paleoecological factors. Information pertaining to the life strategies and the paleoecological requirements of the genera Luehndea, Nannoceratopsis and Valvaeodinium has also been determined. INTRODUCTION The distributions of dinoflagellate cysts are primarily related to paleoenvironmental regimes. Certain dinoflagellate cyst taxa exhibit heterochroneity over wide areas because of differences in paleoecological preferences and overall paleoenvironments (Goodman 1987). This situation has implications for the application of dinoflagellate cysts to intercontinental biostratigraphy (Bucefalo Palliani and Riding 1997a). During the Jurassic two faunal provinces, the Boreal and Tethyan realms, have been distinguished partly on the basis of different ammonite, foraminiferal, brachiopod and calcareous nannofossil assemblages (Arkell 1956; Gordon 1970; Voros 1977; Bown 1987). Biotic differences between these realms may be characterized by relative abundances rather than by the presence or absence of specific taxa (Hallam 1969). The Boreal Realm occupied the northern part of the Northern Hemisphere; the Tethyan Realm lay to the south (Hallam 1969). During the Early Jurassic a broad transitional area with both Boreal and Tethyan biotic characteristics was developed. This intermediate belt comprises southern France, Hungary and Portugal, and was also delineated on the basis of ammonites, calcareous nannofossils and dinoflagellate cysts (Zeigler 1980; Geczy 1984; Cariou et al. 1985; Gardin and Manivit 1994; Baldanza et al. 1995). Within the Tethyan Realm, the macrofaunas allow the Mediterranean and sub-Mediterranean bioprovinces to be distinguished. The former comprises the northern margin of the Tethys Ocean, thus is of European affinity; the sub-Mediterranean is of African affinity, being on the southern margin of Tethys (Pavia and Sarti 1987). Recently these two Tethyan provinces have been differentiated using calcareous nannofossils (Baldanza and Mattioli 1992; Baldanza et al. 1995; Mattioli 1995). The majority of publications on Lower Jurassic dinoflagellate cysts are from the Boreal domain; there are significantly fewer published data from north-west Tethys. The biogeographical distributions of Lower Jurassic dinoflagellate cysts have not been investigated in detail. On the basis of data by Davies (1985) from central Portugal, Tethyan Lower Jurassic microplankton assemblages are broadly similar in generic/specific content to more northerly floras. However, there are several taxa whose stratigraphical ranges differ profoundly from those in the Boreal Realm (Poulsen 1996; Riding and Ioannides 1996). Recently, palynological studies have been carried out on ammoniteand calcareous nannofossil-dated Lower Jurassic Tethyan sections in order to define the stratigraphical ranges of dinoflagellate cysts and to compare them with their ranges in the Boreal Realm (Bucefalo Palliani 1996). The aims of this study are to distinguish and interpret the stratigraphical discrepancies between the two paleogeographical realms, to utilize the stratigraphical data to identify the areas where the main Pliensbachian-Toarcian speciation events occured, to recognize the most important migrational events and consequently the biogeographical factors which drove the dinoflagellate cyst distributions. MATERIAL Samples were collected from several European Pliensbachianearly Toarcian successions (text-fig. 1). The correlations are based on the ammonite, calcareous nannofossil and dinoflagellate cyst content. The Portugese sections, Peniche, Rabacal and Brehna, are outcrop localities in central Portugal, north of Lisbon (text-fig. 2). The Peniche section ranges in age from the early Pliensbachian (Carixian) to the early Toarcian. It consists of intercalations of marls and more calcareous marls with interbedded black shales and detrital crinoidal limestone. The samples studied are from the Lower Pliensbachian (text-fig. 3). The late Sinemurian (Lotharingian) to early Bajocian Brenha road cutting section was dated by Mouterde et al. (1972). The Lower Pliensbachian portion of the section, made up by grey marls with marly limestone beds, has been investigated during this study (text-fig. 3). micropaleontology, vol. 45, no. 2, pp. 201-214, text-figures 1-12, appendix 1, 1999 201 This content downloaded from 207.46.13.51 on Sun, 19 Jun 2016 05:55:42 UTC All use subject to http://about.jstor.org/terms Raffaella B. Palliani and James B. Riding: Early Jurassic dinoflagellate migrations and paleoecology, Boreal and Tethyan realms

Lower Jurassic beds with bivalves in south Slovenia

The Lower Jurassic beds of south Slovenia outcrop on a surface of several hundred km2 with their thickness in places exceeding 300 meters. They were deposited on the Dinaric Carbonate Platform. In them rich accumulations of characteristic bivalves occur that in Pliensbachian and Toarcian inhabited the wide interconnected shallow water regions of the western and Southern margins of Tethys and the eastern Pacific. The most interesting are three large bivalve species: Lithiotis problematica, Cochlearites loppianus and Lithiopedalion scutatus. in addition, numerous other genera can be found: Gervilleioperna, Mytilus, Opisoma and Pachyrisma (with subgenera Pachymegalodon and Durga). The bivalves formed in the region of south Slovenia, in the prevailingly quiet environment of the restricted shelf, sea-bottom mats or biostromes. Their shells can be only rarely found in their growth position. The horizon with bivalves (“lithiotid horizon”) in south Slovenia is attributed to Pliensbachian (Domerian). It is up to 75 metres thick and it almost does not pinch out. Within it individual lumachelles of bivalves occur which are from several centimetres to ten metres thick. They are almost exclusively associated with dark, micritic, in places marly limestone and bituminous dolomite. The biodiversity in lumachelles is very low. The intermediate beds that do not contain bivalves mostly consist of oolitic and biosparitic limestone. In this article some localities from various areas of the carbonate platform are described. Considered are paleogeographical and paleoecological conditions that permitted the existence of this typical bivalve fauna.

Unique record of an incipient ocean basin: Lower Cretaceous sediments from the southern margin of Tethys

A sedimentary sequence documenting the earliest history of the proto-Indian Ocean (Tethys III) was drilled at Ocean Drilling Program Site 761 on the Wombat Plateau off northwest Australia. Directly above a postrift unconformity, three unique, fining-upward Berriasian-Valanginian (Lower Cretaceous) units were recovered which clearly reflect deposition in the earliest oceanic environments. The lower two units are transgressive lag deposits. The uppermost unit is composed of calcisphere-nannofossil chalk and six interbedded bentonite horizons, suggesting a volcaniclastic origin and dacitic to rhyolitic ash as parent material. Volcanic activity was associated with continental breakup and rapid tectonic subsidence during the juvenile phase of the Early Cretaceous Tethys. These sedimentary deposits are characterized by an unusual array of fossil components, including belemnites, and a low-diversity flora of calcispheres and thoracospheres, thought to be opportunistic. Assemblage and isotopic data suggest that this narrow, east-west-trending, incipient ocean basin was highly productive as a result of upwelling of deep waters.

The tectonics of the southern Alps and the Austro-Alpine nappes: a comparison

Summary The southern Alps as well as the Austro-Alpine nappes originate from the southern margin of Tethys with close analogies both in basement petrography and stratigraphic sequence. Although they played vastly different roles in Alpine orogeny they developed similar tectonic features. In both domains there is a ramp-flat geometry with associated folds, analogous to those found in thrust belts worldwide, and the basement consists of thrust plates not more than 5 km thick with a conspicuous frontal ramp fold, complicated by imbrications. Regional décollement levels are at the base of the middle Triassic, the Carnian, and the Rhaetian. Both the southern Alps generally and at least the western end of the Upper Austro-Alpine Lechtal nappe are affected by transverse segmentation which in the southern Alps is demonstrably due to reactivation of Jurassic normal fault zones. Tectonic wedging into the regional décollement layers was a frequent phenomenon. In contrast to the southern Alps, the Silvretta-Lechtal nappe forms part of the Alpine nappe system with total translations of many hundreds of kilometres. It now overlies nappes deriving from different palaeogeographic domains (Lower Austro-Alpine, south Pennine, mid-Pennine, and north Pennine nappes in the Rätikon). Reactivation of the equivalent of the original Lechtal sole thrust, although at a somewhat deeper level within the south Pennine Arosa zone, led to the introduction of exotic Arosa masses into the Carnian interval of the Lechtal nappe, and reactivation of the transverse faults and their propagation to deeper levels resulted in non-cylindrical kinematics of Penninic nappes along the Rhine line.