7 results on '"Samankassou, Elias"'
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2. Evolution of a carbonate delta generated by gateway-funnelling of episodic currents
- Author
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Slootman, Arnoud, De Boer, Poppe L., Cartigny, Matthieu J.B., Samankassou, Elias, Moscariello, Andrea, and Sedimentology
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010506 paleontology ,Turbidity current ,Bedform ,Carbonate delta ,Stratigraphy ,upper-flow-regime bedforms ,Geochemistry ,carbonate delta ,010502 geochemistry & geophysics ,Antidunes ,01 natural sciences ,subaqueous dunes ,Sedimentary structures ,Cyclic steps ,chemistry.chemical_compound ,Sill ,Aggradation ,Supercritical flow ,ddc:550 ,Sicily ,Chute and pools ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,chute and pools ,cyclic steps ,Geology ,cool-water carbonates ,Cool-water carbonates ,Upperflow-regime bedforms ,Subaqueous dunes ,chemistry ,supercritical flow ,Facies ,Carbonate ,Progradation - Abstract
Cool-water carbonate sedimentation has dominated Mediterranean shelves since the Early Pliocene. Skeletal sand and gravel herein consist of remains of heterozoan organisms, which are susceptible to reworking due to weak early cementation in non-tropical waters. This study documents the Lower Pleistocene carbonate wedge of Favignana Island (Italy), which prograded from a 5 km wide passage between two palaeo-islands into a perpendicular, 10 to 15 km wide strait between the palaeo-islands at one side and Sicily at the other during the Emilian highstand (1·6 Ma to 1·1 Ma). The clinoformed carbonate wedge, which is 50 m thick and 6 km long, formed by east/south-east progradation of a platform on the submarine sill by currents that were funnelled between the two palaeo-islands. Platform-slope clinoforms evolved from initial aggradation (thin and low-angle) into a progradation phase (thick and high-angle). Both clinoform types are characterized by a bimodal facies stacking pattern defined by sedimentary structures created by: (i) subaqueous dunes associated with dilute subcritical currents; and (ii) upper-flow-regime bedforms associated with sediment-laden supercritical turbidity currents. Focusing of episodic currents on the platform by funnelling between the islands controlled the downstream formation of a sediment body, here named carbonate delta. The carbonate delta interfingers with subaqueous dune deposits formed in the perpendicular strait. This study uses a reconstruction of bedform dynamics to unravel the evolution of this gateway-related carbonate accumulation.
- Published
- 2019
3. Late Pennsylvanian carbonate platform facies and coral reef: new insights from southern China (Guizhou Province).
- Author
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Maillet, Marine, Huang, Wen-Tao, Li, Xiao, Yang, Zhen-Yuan, Guan, Chang-Qing, Zhang, Yong-Li, Gong, En-Pu, Ueno, Katsumi, and Samankassou, Elias
- Subjects
CORAL reefs & islands ,FACIES ,CORAL reef conservation ,CORALLINE algae ,ALGAL communities ,CORAL communities ,CARBONATES - Abstract
The Pennsylvanian is characterized by intense paleoenvironmental changes related to glacio-eustatic sea-level fluctuations and major tectonic events, which affected the evolution of biocommunities. Most known Pennsylvanian tropical reefs and mounds are predominantly composed of calcareous algae (e.g. phylloid algae, Archaeolithophyllum), calcareous sponges, fenestrate bryozoans, Tubiphytes, and microbialites. However, in Houchang (southern China), the Late Pennsylvanian carbonate platform records a large coral reef lacking any analogs in age (Gzhelian), size (80–100 m thick) and composition (high biodiversity). The large coral reef developed at the border of the Luodian intraplatform basin. The intraplatform basin is characterized by the deposition of green algal grainstone, coated grain grainstone and bioclastic packstone, grainstone, floatstone and rudstone in shallow-waters. In the deep-water shelf, lithofacies are composed of burrowed bioclastic wackestone, microbioclastic peloidal packstone, grainstone, and fine-grained burrowed wackestone and packstone. In this context, the coral reef developed on a deep-shelf margin, in a moderate to low energy depositional environment, below the FWWB. The scarcity of Pennsylvanian coral reefs suggests global unfavorable conditions, which can be attributed to a complex pattern of several environmental factors, including seawater chemistry (aragonite seas), paleoclimatic cooling related to continental glaciation, and the biological competition with the more opportunistic and adaptive phylloid algal community that occupied similar platform margin paleoenvironments. The existence of the large Bianping coral reef in southern China, as well as a few additional examples of Pennsylvanian coralliferous bioconstructions, provides evidence that coral communities were able to endure the Late Paleozoic fluctuating paleoenvironmental conditions in specific settings. One of such settings appears to have been the deep shelf margin, where low light levels decreased competition with the phylloid algal community. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
4. The onset of the major glaciation of the LPIA: record from South China.
- Author
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Huang, Wentao, Maillet, Marine, Zhang, Yongli, Guan, Changqing, Miao, Zhuowei, Samankassou, Elias, and Gong, Enpu
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GLACIAL Epoch ,CARBON isotopes ,STROMATOLITES ,LIMESTONE ,FACIES - Abstract
The beginning of the Late Paleozoic Ice Age was characterized by localized events with small ice depocenters occurring in South America and a series of cyclic shallow-water limestones in far-field regions, in late Visean to Serpukhovian. This paper documents two topmost Visean–Serpukhovian sections in Guangxi, South China: a stromatolite-bearing deep-water succession in Helv village and a shallow-water succession in Dujie village. Seventeen microfacies types have been recognized and grouped into six microfacies associations. The vertical evolution of the microfacies associations from deep-water to shallow-water depositional environments in both sections indicate a major relative sea-level fall in the latest Visean. The repetitive successions comprising different morphological stromatolites in Helv section and the cyclic alternation of subtidal and peritidal facies in Dujie section imply high-frequency sea-level fluctuations during latest Visean to Serpukhovian, most likely eustatic in origin. The carbon isotope data of Dujie limestone exhibit a pronounced positive δ
13 C excursion with ± 4.3‰ in the peritidal deposits. This shift is interpreted as the result of enhanced organic carbon burial in other regions and depletion of the ocean in light carbon. The widespread coeval cyclicity occurring in settings in South China, Western Europe, and North America is most likely the results of glacio-eustatic sea-level fluctuations, possibly with local influences of tectonic movements. This pattern is interpreted to represent the expression of the onset of the major glaciation during the LPIA in low-latitudinal successions. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
5. Short-lived early Cenomanian volcanic atolls of Mt. Carmel, northern Israel.
- Author
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Bialik, Or M., Samankassou, Elias, Meilijson, Aaron, Waldmann, Nicolas D., Steinberg, Josh, Karcz, Kul, and Makovsky, Yizhaq
- Subjects
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CORAL reefs & islands , *MARINE ecology , *GREEN algae , *SEA level , *FACIES - Abstract
Volcanic atolls host exceptionally important marine ecosystems in the modern oceans. Yet, due to limited exposures, fossil atolls are poorly constrained. Multiple drowned Cretaceous volcanic atolls have been reported in the Pacific, but less information exists regarding those in the Tethys. Here we report on two early Cenomanian age volcanic atolls outcropping in Mt. Carmel (northern Israel), along the eastern Levant margin. These atolls are a few kilometers in diameter and differ significantly in facies from their surroundings, which are dominated by chalky calcareous mudstone and wackestone. The atolls are composed of grainstone, floatstone, rudstone and bafflestone facies, which are dominated by molluscans, notably gastropods, rudists, oysters and other bivalves. Corals and green algae are absent throughout these atolls. The studied sections of these atolls display a full succession, beginning with aggradation and ending with drowning. Age constraints for the volcanic phases suggest that deposition occurred within a relatively short time interval (<1 Myr) and the sequence represents a keep-up to give-up transition, within rising global and local sea-level trends. The inability of these atolls to keep up with rising sea level is attributed here to a suppressed carbonate factory, either due to drowning, turbidity and/or nutrient excess. Our study sheds new light on the dynamics of carbonate buildups during the Late Cretaceous and their ability to persist. • We describe two km scale Cenomanian volcanic atolls from northern Israel. • These atolls offer a unique window into the details of succession in Late Cretaceous atolls. • The atolls exhibit a heterotrophic assemblage which was sustained for a relatively short time. • Data point to reef demise due to factors other than light limitation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Hydrocarbon potential, palynology and palynofacies of four sedimentary basins in the Benue Trough, northern Cameroon.
- Author
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Bessong, Moïse, Hell, Joseph Victor, Samankassou, Elias, Feist-Burkhardt, Susanne, Eyong, John Takem, Ngos, Simon III, Nolla, Junior Désiré, Mbesse, Cecile Olive, Adatte, Thierry, Mfoumbeng, Marie Paule, Dissombo, Edimo André Noel, Ntsama, Atangana Jacqueline, Mouloud, Bennami, and Ndjeng, Emmanuel
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HYDROCARBONS , *PALYNOLOGY , *SEDIMENTARY basins , *FACIES , *STRATIGRAPHIC geology - Abstract
Organic geochemical, palynological and palynofacies analyses were carried out on 79 selected samples from four sedimentary basins (Mayo-Rey, Mayo-Oulo-Lere, Hamakoussou and Benue) in northern Cameroon. Rock-Eval pyrolysis and Total Organic Carbon results indicate that most of the samples of the studied basins are thermally immature to mature. The organic matter consists of terrestrial components (peat, lignite, bituminous coal, and anthracite) associated with organic matter of marine origin. Based on the appraisal of multiple parameters: Total Organic Carbon (TOC), maximum Temperature (T-max), Hydrogen Index (HI), Oxygen Index (OI) and Production Index (PI), some samples are organically rich both in oil and/or gas-prone kerogen Type-II, II/III and III. The source rock quality ranges from poor to very good. The source material is composed of both algae and higher plants. Samples from these basins yielded palynological residue composed of translucent and opaque phytoclasts, Amorphous Organic Matter (AOM), fungal remains, algal cysts pollen and pteridophyte spores. Abundance and diversity of the palynomorphs overall low and include Monoporopollenites annulatus (= Monoporites annulatus ), indeterminate periporate pollen, indeterminate tetracolporate pollen, indeterminate tricolporate pollen, indeterminate triporate pollen, indeterminate trilete spores, Polypodiaceoisporites spp., Biporipsilonites sp., Rhizophagites sp., Striadiporites sp., Botryococcus sp. (colonial, freshwater green algae), and Chomotriletes minor (cyst of zygnematalean freshwater green algae). Age assigned confidently for all these basins the palynological data except for one sample of Hamakoussou that can be dated as Early to Mid-Cretaceous in age. Callialasporites dampieri , Classopollis spp., Eucommiidites spp. and Araucariacites australis indicate, an Aptian to Cenomanian age. The other pollen and spores recovered may indicate a Tertiary or younger age (especially Monoporopollenites annulatus ), or have arisen from modern contamination. Geochemical data show that sediments are wackes, arkose, iron-sandstone and iron-shale. The Chemical Index of Alteration (CIA-K) is low moderate to high, suggesting a shorter exposure time and fast erosion and transport. The studied sequences cover various depositional settings ranging from wetlands to dry environment inside island arc, passive margin or active continental margin. This study reveals new data and the economic potential of this part of Cameroon. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
7. Facies, geometry and stratal patterns of the Valdorria carbonate platform (Pennsylvanian, Northern Spain)
- Author
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Chesnel, Valentin and Samankassou, Elias
- Subjects
Milankovitch ,Valdorria ,Progradation ,Steep slope ,Facies ,Aggradation ,Pennsylvanian, Bashkirian ,Flat top ,Cyclothems ,Eccentricity ,Carboniferous ,Carbonate platform ,Spain ,Cantabrian Mountains ,Microbial boundstone ,ddc:550 ,Lateral distribution of organisms - Abstract
Carboniferous carbonate platforms are known to develop high-relief, flat top and steep microbial-boundstone slopes. Prominent examples were reported from the Bashkirian–Moscovian of northern Spain and are commonly used as analogues for contemporaneous hydrocarbon reservoirs, e.g., in Kazakhstan and the Pricaspian Basin (Tengiz, Karachaganak, Kashagan and Astrakhan fields). Here we report on the isolated Valdorria carbonate platform, formerly equally named Valdeteja platform, located in the southern part of the Cantabrian Mountains, in northern Spain. The outcrop shows a 14 km-wide complete sequence, from platform nucleation to demise, and entirely exposes a flat top, a high relief slope and primarily horizontal basin deposits. Laterally and vertically traceable stratal patterns exhibit three phases of growth, each delimited by a major discontinuity surface presenting dissolution, karsts and/or calcretes features.
- Published
- 2016
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