Biostratigraphy of Baghamshah Formation based on calcareous nannofossils in the Southwest Tabas, Iran

The Tabas Block is part of the Central Iran microcontinent, located between the Lut Block in the East and the Yazd Block in the West. The Baghamshah Formation is the second lithostratigraphic unit from the sedimentary cycle of the Magu Group and the Baghamshah Subgroup in the Jurassic of Tabas Block. This formation is conformably underlaid with the grey pisoidal limestones of the Parvadeh Formation and overlaid with the Pectinid limestones of the Kamar-e-Mehdi Formation (Esfandiar Subgroup). In this research, the biostratigraphy of the Baghamshah Formation in the Rizu and Kamar-e-Mehdi sections, based on calcareous nannofossils, is examined. The thickness of the Baghamshah Formation in the Rizu section is 270 m (mostly including marl and green shales with intercalation of limestones and calcareous sandstones), and in the Kamar-e- Mehdi section is 236 m (composed of gypsiferous marly shales, marl, marly shales and alternation of marl-shale with limestones and calcareous sandstones). According to the taxonomic studies in the Rizu section, 52 species belong to 24 genera, and in the Kamar-e-Mehdi section, 45 species belong to 23 genera of calcareous nannofossils. Based on index calcareous nannofossils, the CC1, CC2, CC3, and CC4 biozones established by Sissinghh in both sections were determined. It is mentioned that CC5 biozone only occur in Kamar-e-Mehdi section. According to the identified biozones, the suggested age of the Baghamshah Formation is early Berriasian–early Hauterivian in the Rizu section, and early Berriasian–late Hauterivian in the Kamar-e-Mehdi section. Keywords: biostratigraphy, Baghamshah, calcareous nannofossils,Tabas, Iran.

Stratigraphy and Sedimentology of Upper Cretaceous to Upper Palaeocene Succession in Zimam Formation Along Wadi Tar al Kabir, NW Libya

The Upper Cretaceous to Upper Palaeocene rocks of the Zimam Formation along the southwestern escarpment of the Hun Graben of NW Libya have been stratigraphically investigated from two stratigraphical sections in wadi Tar al Kabir. The field investigations led to the recognition of three members, from the oldest to the youngest, the Lower Tar Member, the Upper Tar Member and the Had Member. Eight sedimentary facies were distinguished at outcrop-scale and several microfacies were recognized and the outcome indicates that the depositions of the Zimam Formation are corresponding to two transgressive-regressive sedimentary cycles. The first cycle is attributed to the Lower Tar Member in which small planktonic foraminifera is quite common in the Campanian whereas the larger benthic foraminifera, namely, Omphalocyclus macroporus and Siderolites calcitrapoides are abundant in the Maastrichtian. The last occurrence of the latter two taxa, however, was used to delineate the contact between the Maastrichtian and Danian stages in the studied sequence. Up-sequence the sediments of the Upper Tar Member along with the overlying Had Member correspond to the second transgressive-regressive sedimentary cycle. Herein, the Upper Tar Member is enriched by small benthic foraminifera; Neoeponides duwi and Cibicides cf. libycus, and has been ascribed to the Danian (Lower Palaeocene). The reaming sediments of Zimam Formation, however, are belonging to the overlying Had Member and is tentatively ascribed to the Selandian (Upper Palaeocene) based on the last occurrence of the Danian fauna and the total range of the codiacean algae Ovulites morelleti.

Treatment and reinforcement of the loose sands of the city of Kenitra

The Kenitra city belongs to the Rharb-Mamora domain, which is affected by a continuous subsidence from the Middle Vindobonien to the present day. The sedimentary cycle of the tertiary era ends at the Pliocene, characterized by regressive character deposits identified in outcrop at the margins of the basin: They are conglomerates in the North, yellow sands in the East, sands and sandstone in the South-East. These sandy deposits vary from more or less clayey sand to greying sand, with the appearance of a very loose sand layer, at varying depths. It is with this directive that the objective of this article is to define the risks, which may affect the works built on this soil, and also determine the actions to be taken to control these risks. As a first step, an experimental approach was carried out, including in situ and laboratory tests in order to identify these formations and define their mechanical behavior. Then, the results of geotechnical survey were analyzed and exploited in calculations of bearing capacity, settlement, liquefaction,… eventually resulting in the necessity of treatment and reinforcement of this soil. These approaches have shown that there are several soil reinforcement techniques, the choice of which depends on the granulometry of soil and the cost of project.

Petrographic Assessment of Some Industrial Minerals in Selected Part of Southern Benue Trough, Nigeria

Some part of the Southern Benue Trough (Afikpo and Anambra Basins) has been mapped to determine the areas of occurrence of industrial minerals and to determine their lateral extent. The result shows that Southern Benue Trough is enriched with mostly industrial minerals of sedimentary and magmatic origin. The magmatism that occurred in the study area and its evolutionary processes led to mineralization of the study area. Interaction of the magma with host rocks gave rise to mineral genesis. The contamination and assimilation processes that occurred in the magmatic stage resulted to enrichment of minerals in the study area. The contact relationship of the magma with the host rock created a contact aureole though the resultant minerals (metamorphic minerals) of the contact aureole are not significant and exposed. The repetitive transgressive-regressive sedimentary cycle that occurred in the Southern Benue Trough probably resulted to the massive deposition of industrial minerals of sedimentary origin. The dominant and significant industrial minerals in Afikpo and Anambra Basins are sandstones (ferruginized sandstone, calcareous sandstones and carbonaceous sandstones), clay mineral (kaolinite), pebbles, igneous rocks of diverse levels of emplacement (intrusive/ extrusive), olivine , hematite, Feldspar, mica and quartz.

The carbonates of the post-Variscan basins of Sardinia: the evolution from Carboniferous–Permian humid-persistent to Permian arid-ephemeral lakes in a morphotectonic framework

Late to post-Variscan sedimentary basins of Sardinia were influenced during Pennsylvanian to Permian times by two main tectono-sedimentary cycles: a Pennsylvanian to Cisuralian cycle represented mainly by dark limnic deposits, overlain by a Guadalupian to a possibly Lopingian cycle, mostly characterized by red-bed deposits. Lacustrine waterbodies developed in some sedimentary basins that were filled with siliciclastic to frequently early silicified carbonate deposits, depending on the climate and environmental conditions, landscape morphology and tectonic regime. The limnic successions of the lower tectono-sedimentary cycle were deposited in permanent, tens of metres deep lakes in deep, narrow tectonic strike-slip basins under a temperate to warm-humid climate. They started as lakes with terrigenous sedimentary input and developed minor carbonate deposits mainly at the end of their story. Conversely, the red-bed successions of the upper cycle were deposited in ephemeral, shallow playa lakes related to wider basins in an extensive alluvial plain under a hot and arid climate. Here, the siliciclastic sediments are intercalated with thin carbonate beds that are typical of a high evaporation rate. The evolution of the lake type could be related not only to a major climatic shift, but also to the changing morphotectonic conditions of the Variscan chain influencing the local microclimate. Comparisons with coeval successions in the Provence Basin, the Massif Central Aumance basin (France) and the Saar–Nahe Basin (Germany) show both similarities and differences between the basins.

The Sedimentary Cycle on Early Mars

Two decades of intensive research have demonstrated that early Mars ([Formula: see text]2 Gyr) had an active sedimentary cycle, including well-preserved stratigraphic records, understandable within a source-to-sink framework with remarkable fidelity. This early cycle exhibits first-order similarities to (e.g., facies relationships, groundwater diagenesis, recycling) and first-order differences from (e.g., greater aeolian versus subaqueous processes, basaltic versus granitic provenance, absence of plate tectonics) Earth's record. Mars’ sedimentary record preserves evidence for progressive desiccation and oxidation of the surface over time, but simple models for the nature and evolution of paleoenvironments (e.g., acid Mars, early warm and wet versus late cold and dry) have given way to the view that, similar to Earth, different climate regimes on Mars coexisted on regional scales and evolved on variable timescales, and redox chemistry played a pivotal role. A major accomplishment of Mars exploration has been to demonstrate that surface and subsurface sedimentary environments were both habitable and capable of preserving any biological record. ▪ Mars has an ancient sedimentary rock record with many similarities to but also many differences from Earth's sedimentary rock record. ▪ Mars’ ancient sedimentary cycle shows a general evolution toward more desiccated and oxidized surficial conditions. ▪ Climatic regimes of early Mars were relatively clement but with regional variations leading to different sedimentary mineral assemblages. ▪ Surface and subsurface sedimentary environments on early Mars were habitable and capable of preserving any biological record that may have existed.