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Search Results: 1 - 10 of 41 matches for " Maastrichtian "
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Late Maastrichtian Calcareous Nannofossil Biostratigraphy and Paleoecology of the Tamera Well, Siwa Area, Western Desert, Egypt  [PDF]
Esam Zahran
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.46091
Abstract:

The upper Cretaceous interval of the Khoman Formation in the Tamera well, Siwa area, Western Desert of Egypt was studied for the first time on the basis of calcareous nannofossils. Twenty-one nannofossil species were identified from this interval. The study interval includes the Micula murus Zone, which is precisely dated as Late Maastrichtian age. The Micula murus Zone includes besides the marker species: Micula decussata, Watznaueria barnesae, Arkhangelsktella cymbiformis and relatively rare occurrences of Eiffellithus turrisieffellii, Cribrosphaerella ehrenbergii, Thoracosphaera operculata and

Microbiostratigraphy of the Tarbur Formation, Zagros Basin, Iran
I. Maghfouri-Moghadam,R. Zarei-Sahamieh,A. Ahmadi-Khalaji,Z. Tahmasbi
Journal of Applied Sciences , 2009,
Abstract: The Tarbur Formation is a predominately carbonate lithostratigraphic unit that outcrops in Zagros basin, between main Zagros reverse fault and high Zagros and east of Sabzpushan faults. This Formation was studied from microbiostratigraphic point of view at four measured sections, in the north of Khorram Abad (Robat section) in the east of Khorram Abad (Chamsngar section) in the east of Shirz (Sarvestan section) and in the south east of Semirum (Balghar section). Microbiostratigraphical data mainly based on foraminifera which among them, species of Loftusia have more variety and abundance, so the species of Loftusia from the measured sections are used to determine the age of successions. It is analogous to Omphalocyclus-Loftusia assemblage zone but according to the distribution of the index species of Loftusia the age of Tarbur Formatoin is Early-Middle Maastrichtian at Sarvestan section and Middle Maastrichtian for Balgar, Robat and Chamsangar sections.
Reassessment of the Resources of a Deep Aquifer System under Physical and Chemical Constraints:The Maastrichtian Aquifer  [PDF]
Cheikh Hamidou Kane, Moustapha Diene, Meissa Fall, Baba Sarr, Alassane Thiam
Journal of Water Resource and Protection (JWARP) , 2012, DOI: 10.4236/jwarp.2012.44024
Abstract: The deep and confined Maastrichtian aquifer contains considerable groundwater resources. It stretches over nearly 200,000 km2, from the northern part of Mauritania to the South of Guinea Bissau where it becomes shallow. The reservoir is composed mainly of coarse sands and sandstone interbedded with some clay units. The aquifer provides 40% of the total drinking water extracted from the different aquifers and nearly 800 wells equally distributed operate only in the top 50 m of the aquifer. Despite the importance of these resources for providing water in the rural and urban areas, the aquifer characteristics are not well defined. The present paper aims to define first the physical and chemical characteristics of the Maastrichtian aquifer. The reserve of the aquifer initially estimated at 350 billion m3, is reassessed using new data providing from cross sections realized as part of our research, through the Water Sectorial Project of the Ministry of Hydraulics. Data from oil wells and geophysical logging are used to investigate the geometry of the aquifer and the position of the fresh/salty water interface. The highest thickness of the aquifer is between 200 to 400 m and salty water is present below the fresh groundwater in the west side of the aquifer. In the Eastern side, potable water lies directly above the basement. The thickness of the aquifer increases from the west to the center, and then decreases towards the shallow basement rock in the South East. The average thickness is 250 m. Chemical data coming from pumping wells indicate high chloride (250 - 1600 mg/l) and fluoride content (1 - 5.5 mg/l). Therefore, the reassessment has to take into account the chemical aspect of the water.
First record of Elasmosaurid Plesiosaurs (Sauropterygia: Plesiosauria) in upper levels of the Dorotea Formation, Late Cretaceous (Maastrichtian), Puerto Natales, Chilean Patagonia
Otero,Rodrigo A; Suárez,Mario E; Le Roux,Jacobus P;
Andean geology , 2009,
Abstract: new remains of plesiosaurs (diapsida; sauropterygia) found in a transported block correlated with upper levels of the dorotea formation, late cretaceous (maastrichtian) are describedherein. they were collected on the southern slopes of sierra dorotea located northeast of puerto natales (51 °41 '20,4"s, 72°26'07,4"w), magallanes región, chile. this is the first disco very of the family elasmosauridae in high latitudes of south america, complementing the previously known paleodistribution of this group in the eastern pacific ocean and the antarctic during the latest cretaceous.
Presence of a maniraptoriform dinosaur in the Late Cretaceous (Maastrichtian) of Chiapas, southern Mexico
Carbot-Chanona, Gerardo;Rivera-Sylva, Héctor E.;
Boletín de la Sociedad Geológica Mexicana , 2011,
Abstract: here is described the first dinosaur evidence from chiapas, and also the southernmost evidence of dinosaurs in mexico. a small theropod tooth, identified as richardoestesia isosceles, based on its shape and the presence of small denticles on the mesial and distal carinae with rounded outline, was collected in the ocozocoautla formation (late cretaceous, maastrichtian). these results extend the fossil record of this taxon in north america, as it is the southernmost record of richardoestesia and the first report of this genus in mexico.
Primera ictiofauna marina del Cretácico Superior (Formación Jaguel, Maastrichtiano) de la provincia de Río Negro, Argentina
Bogan, Sergio;Agnolin, Federico L.;
Papéis Avulsos de Zoologia (S?o Paulo) , 2010, DOI: 10.1590/S0031-10492010001200001
Abstract: this paper describes several fossil teeth coming from marine sediments from the bajo trapalcó locality, río negro province, patagonia, argentina. the ichthyofauna described here is composed by six different chondrichtyan taxa (serratolamna serrata, squalicorax pristodontus, cretalamna appendiculata, carcharias sp., odontaspis sp. and cf. pseudohypolophus mcnultyi) and two teleostei of the genus enchodus (aff. e. ferox and aff. e. gladiolus). serratolamna serrata is the most abundant species, and it represents the southernmost record for the species and the first record for argentina. the records of enchodus, squalicorax pristodontus and cf. pseudohypolophus mcnultyi, constitute the first mention for these taxa in argentina. the taxa described here characterize the paleoichthyofaunas of the upper cretaceous seas from different regions of the world, contributing with new information toward the comprehension of the mesozoic ichthyofunas from the southern regions of south america.
Nuevo registro de gasterópodos en la Formación Yacoraite (Maastrichtiano-Daniano) Cordillera Oriental de Jujuy, Argentina: sistemática, bioestratigrafía y correlación geológica
Cónsole Gonella,Carlos A;
Serie correlaci?3n geol?3gica , 2011,
Abstract: we present a new record of gastropods recovered in limestones of the yacoraite formation (maastrichtian-danian) in jueya environs, cordillera oriental of jujuy, argentina. has been identified 91 fossils, distributed in the genera: brachycerithium bonarelli 1921; bonarelliella n. gen. and percossmannella n. gen. has been defined the species brachycerithium evolutum bonarelli 1921; brachycerithium minus bonarelli 1921; brachycerithium ferugloi? bonarelli 1921; bonarelliella jueyai sp. nov; bonarelliella ameghinorum bonarelli 1927 (cónsole gonella nov. comb.); bonarelliella brackebuschii sp. nov; bonarelliella multicosta bonarelli 1927 (cónsole gonella nov. comb.) and percossmannella steinmannii sp. nov. as result of the research, the affinities and bioestratigraphic range of this fauna are still open to highest levels.
La estabilidad evolutiva de los foraminíferos planctónicos en el Maastrichtiense Superior y su extinción en el límite Cretácico/Terciario de Caravaca, Espa?a
Arz,José A.; Arenillas,Ignacio; Molina,Eustoquio; Sepúlveda,Rodolfo;
Revista geológica de Chile , 2000, DOI: 10.4067/S0716-02082000000100003
Abstract: planktonic foraminiferal stability in the upper maastrichtian and the catastrophic mass extinction at the cretaceous-tertiary (k/t) boundary at caravaca (spain). the planktic foraminiferal quantitative and biostratigraphic study across the k/t boundary at the caravaca section provides proof of the stratigraphical range continuity and the evolutive stability of species in the upper maastrichtian. in caravaca, the planktic foraminiferal extinction pattern is a catastrophic mass extinction since 74% of the species went extinct in coincidence with the k/t boundary and with the evidence of impact. this pattern can be similarly identified in other tethyan sections and, for this reason, the authors consider that the supposed extinctions suggested by other authors in caravaca could be caused by the signor-lipps effect. in this study, it was found that possibly 17 cretaceous species survived the k/t event and their relative abundance suddenly drops above the k/ t boundary (arecs curve). this decrease can be a consequence of the progressive decline in abundance of the cretaceous species that survived due to biological competition with the new tertiary species or, simply, the decrease in the relative proportion of reworked specimens. nevertheless, independently of the fact that some species survived the k/t event, the existence of a gradual extinction pattern in the lowermost part of the danian does not refute the hypothesis of a catastrophic event in coincidence with the k/t boundary. the k/t planktic foraminiferal catastrophic mass extinction of more than 70% is very compatible with the hypothesis of the impact of a large asteroid and its effects in the short, middle and long term
Late Cretaceous (Maastrichtian) foraminiferal assemblage from the inoceramid beds, Ocozocoautla Formation, central Chiapas, SE Mexico
Oma?a, Lourdes;
Revista mexicana de ciencias geológicas , 2006,
Abstract: foraminifera from samples collected in the lower part of the ocozocoautla formation were studied. this sequence crops out north-west of tuxtla gutiérrez in central part of chiapas state in south-eastern mexico. the lower part of the unit consists mostly of argillaceous and marly sandstone with inoceramids. this horizon yields a poorly preserved but biostratigraphically useful foraminiferal assemblage. the upper part of the gansserina gansseri zone is defined on the basis of the planktic foraminiferal association. an early maastrichtian age has been assigned, rather than late campanian-maastrichtian as previously determined in the literature. the environment was interpreted as outer shelf-upper slope with tethyan affinities, on the basis of the benthic and planktic foraminiferal association.
Latest Maastrichtian foraminiferal assemblages from the Husów region (Skole Nappe, Outer Carpathians, Poland)
M. Adam Gasiński, Alfred Uchman
Geologica Carpathica , 2009, DOI: 10.2478/v10096-009-0020-5
Abstract: The Ropianka Formation (also known as the Inoceramian Beds) in the marginal part of the Skole Nappe (Husów region, the Gaj section) contains abundant, diverse and well preserved assemblages of Maastrichtian planktonic and benthic foraminiferids, assigned to the middle-upper part of the Gansserina gansseri Zone and to the Abathomphalus mayaroensis Zone. The composition of the assemblages indicates fluctuations of organic matter flux to the marginal part of the Skole Basin floor in the studied interval. The studied taxa are typical of the "transitional zone" between the Tethyan and the Boreal domains. The disappearance of planktonic foraminifers in the uppermost part of the section and appearance of some agglutinated taxa (Rzehakina fissistomata; abundant Conglophragmium irregularis and Glomospira charoides) points to a Paleocene age.
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