Faunal association of Bidestan and Howz-e-Khan Members characterized Norian- Rhaetian stages. Qadir Member contains Clathropteris sp. and Indopecten glabra. They indicated Rhaetian stage. Nayband formation is overlain unconformably by the Lower Cretaceous of conglomerates and sandstones. One big gap can be recognized in Jurassic time in Central Iran. Red conglomerate show transgression phenomena at the time of Early Cretaceous in Central Iran. Pebbles of conglomerate have several sources. There is no evidence of Jurassic fossils like Ammonite or microfossil in Early Cretaceous conglomerate. The lack of a part of Liassic, Dogger and Malm and Neocomian sediments related to Cimmerian phase.
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Abstract.- The Lower Jurassic Ab-Haji Formation of the Kalmard, Tabas and Lut blocks, east-central Iran, has been studied using an integrated stratigraphic-sedimentologic approach. The Ab-Haji Formation is mostly composed of greenish sandstones and siltstones and locally contains thin coal seams. Four well exposed sections were measured and studied in order to identify lithofacies and facies associations and to interpret the palaeoenvironment. This formation reaches a thickness up to 350 m in northern Tabas Block but may locally be reduced to few tens of meters or even missing. Field studies have led to the recognition of sixteen lithofacies grouped into five facies associations: fluvial plain, coastal plain, delta front, prodelta and shallow siliciclastic shelf. Reconstruction of the palaeogeography of east-central Iran marks a west–east continental-to-marine gradient. Thickness variations, lateral facies changes and basal unconformity of the siliciclastic rocks of the Ab-Haji Formation on the Kalmard, Tabas and Lut blocks show palaeo-relief on the fault-bounded Yazd Block in the west and the Shotori Swell at the eastern edge of the Tabas Block. The pattern of thickness variations and rapid EW facies changes is best explained by a tectonic model showing large tilted fault blocks in an extensional basin. The obtained results are important for palaeogeographic and palaeoenvironmental reconstructions of the east-central Iran since its sediments record the geodynamic history of this region, as well as an even larger area, during and in the aftermath of the main Cimmerian event, from the beginning of the Early Jurassic.
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The early Miocene Qom Formation is exposed in the Bagh section, northeast Isfahan, Central Iran, where it unconformably overlies Oligocene deposits and is unconformably overlain by the Upper Red Formation. The formation is mainly represented by carbonate deposits (marl, marly limestone facies) and subordinate siliciclastic facies. The planktonic foraminiferal biostratigraphical analysis led to recognition of two main planktonic foraminiferal zones: 1. the Globigerinoides primordius Zone in the lowermost part of the section indicating early Miocene (Aquitanian) and 2. the Globigerinoides trilobus Zone in the upper most part of the Qom Formation of Burdigalian age (early Miocene). Composition and abundance of benthic and planktonic foraminifers were examined for paleo- environment reconstruction and paleoecology. The Q-mode cluster analysis performed on the benthic foraminifers led us subdivide the section into three distinct benthic foraminiferal clusters: I. the Cibicidoides ungerianus cluster in the lower part of succession, indicating predominantly inner neritic environments; II. the Lenticulina orbicularis cluster in the middle part of section, indicative of middle-outer neritic environments, and III. the Elphidium-Amphistegina cluster recorded in the upper part of the formation and characterizing a typical outer neritic environment. The planktonic foraminifers are interspersed in the upper part of the section with relatively low diversity, indicating open marine shelf segments, whereas the lower part of the section is characterized by an abundance of benthic foraminifers. As a point to consider for paleoecology and paleoenvironment, abundant although with low diversity benthic foraminifera with small tests, and calculated data based on these clusters are indicative of high nutrient and high oxygen environment with normal marine salinity during the early Miocene at the Bagh section.
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The Upper Cenomanian to Campanian rocks (Sadr unit) crop out across a large area of Nakhlak and reach a thickness of 258 m in the studied section (Figure. 1). This section is situated south of Nakhlak village (coordinates: N 33˚32’09”; E 53˚50’33”) and consists of conglomerates, sandy limestones, calcareous sandstones, sandy dolostones, sandy-argillaceous limestones, sandy dolomitic limestones, and reefal limestones that have been subdivided into ten sub- units on the basis of their facies characteristics and described (Figure 2; Vaziri et al., 2005). The rich foraminiferal assem- blage from different sub-units of the studied section indicates a Late Cenomanian to Campanian age (Khosrow-Tehrani, 1977; Vaziri et al., 2005). Biostratigraphic studies of the Upper Cretaceous rocks of the Nakhlak (Khosrow-Tehrani 1977; Vaziri et al., 2005), Choopanan and Hafttoman areas (Khosrow-Tehrani, 1977), as well as of the Kerman area of east-central Iran (Faryabi, 2003) point to a hiatus during Turonian-Coniacian time.
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Abstract.- Three stratigraphic sections of the Early Carboniferous Gachal Formation in the Kalmard area, central Iran were studied. The Gachal Formation shows alternation of siliciclastics and carbonates in repeated cyclic arrangements. The microfacies and depositional environment are described and reconstructed. Facies analyses indicate the presence of seven carbonate and one siliciclastic facies types, which are indicative of back-, inner- and middle-ramp settings. A mixed siliciclastic-carbonate ramp setting is proposed for the depositional environment of the Gachal Formation. This mixed lithology has only been reported from that central Iranian formation. The Mobarak Formation, coeval deposits of the Gachal Formation, in Alborz (northern Iran) is mainly composed of carbonates. The facies analysis of the carbonate portion of the Early Carboniferous Gachal Formation shows some resemblance with those of the Mobarak Formation, even though middle- and outer-ramp facies are more abundant in the Mobarak Formation. During the latest Tournaisian- earliest Visean third-order, shallowing-upwards depositional sequences were recognized in the Gachal Formation in the study area. Tectonic activity (fault movements) was the main reason for thickness variations of the Gachal Formation members in these three studied section. Synsedimentary tectonic activity must have been responsible for the platform rising, leading to the erosion that created the siliciclastic influx into the Carboniferous basin in the Kalmard area. Our results show the importance of synsedimentary tectonics on the development of carbonate facies.
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units to be recognized in the studied area, separated by ophiolite-bearing sutures. Other criteria such as structural style, the age and intensity of deformation, and the age and nature of magmatism are used to subdivide these major zones into smaller elements. The three major units and their main constituents are as follows: 1) the southern unit, with a crystalline basement consolidated in Precambrian time, platform-type Paleozoic sediments and younger deposits. This unit comprises the Zagros fold belt; 2) the central unit, interpreted as an assemblage of marginal Gondwana fragments, originally united with the main continent and separated from the North (Eurasian) continent during the Paleozoic. In Mesozoic times, these fragments were detached from Gondwana and attached to Eurasia. During the Late Cretaceous they rejoined the Gondwanic Afro-Arabia. This unit comprises Central Iran and the Alborz; 3) the northern unit, markedly separated from the central unit by ophiolites of the North Iran suture. The continental crust includes remnants of more or less cratonized, former (Paleozoic) oceanic crust possibly that of the Paleotethys. The northern unit represents a marginal strip of the Hercynian realm of Central Asia, broadly overlapped by the Alpine realm. It was deformed and largely consolidated by strong Early Cimmerian and Late Alpine folding (Stocklin, 1968). The Northern Unit comprises the South Caspian Depression and the Kopet-Dagh Range (Figure 3).
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This study was completed at the University of Isfahan and supported by the Office of Graduate Studies, and the authors are grateful to the office for their support; we also want to thank Mrs. Rahmati, Bsc student, for the first collection samples and the Instituto de Geología, UNAM for their support in field trips and sampling North of Isfahan, Central Iran. Valuable comments to the original manuscript were offered by Rodney M. Feldmann (Kent State University). Our sincere gratitude is given to Ron Blakely (Northern Arizona University) for his permission to use a paleogeographic map.
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River Nyong, the second biggest river in Cameroon and main attraction point in Ebogo, rises in the east of Cameroon and flows across all of the Central and South provinces covering a 640 km course before emptying into the Gulf of Guinea of the Atlantic Ocean, at Petit Batanga. This river is noted for its black color which is characteristic of alluvials deposits, with a surface layer rich in humus. The vegetation, made of secondary forest, contains valuable forest species such as Ayous, Moabi, Iroko, Sappelli, Dibetu, Bibunga, etc. You may also get the chance to visit Ebogo village and see the famous “bantou huts” (constructed from raw produce of Mother Nature). See annex 4 for pictures on Ebogo tourist site.
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Three sections of the Oligocene-Miocene Asmari Formation, crossing central and north-central Zagros foreland basin in SW Iran, were measured and studied in order to interpret the biostratigraphy, paleoecology (based on distribution of benthic foraminifera) and diagenesis. Forty-three foraminifer genera and species were encountered in the studied areas and the following assemblage zones have been defined: 1) Nummulites vascus-Nummulites fichteli, 2) Lepidocyclina-Operculina-Ditrupa, 3) Archaias asmaricus-Archaias hensoni-Miogypsinoides complanatus, 4) Miogypsina-Elphidium sp. 14 - Peneroplis farsenensis, and 5) Borelis melo curdica-Borelis melo melo. According to this study, deposition of the Asmari Formation with association of hyaline, lamellar, perforate large and flat foraminifera first started in the basin and slope environments during the Rupelian in Dehdez and Tufe-Sefid areas. Lagoon depositional environment colonized by sea-grass epiphytic foraminifera was encountered during Chattian and Aquitanian in Bagh-e Malek and Dehdez areas and mostly lagoon and slope environments prevailed during Burdigalian in Bagh-e Malek and Dehdez areas, respectively. The main diagenetic processes that affected the Asmari Formation were dolomitization (replacement and cementation), compaction (stylolitization) and dissolution. The extent of these diagenetic overprinting seems to be mainly facies controlled.
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«Una forma de cooperació internacional no reglada és el càrtel internacional. Quan, en lloc d’empreses, són països els que cooperen per repartir-se el mercat o fixar els preus es parla de càrtels internacionals. El càrtel més important del món és el de l’Organització de Països Exportadors de Petroli (OPEP). Fundat el 1960, actualment está format per Aràbia Saudita, Iraq, Iran, Kuwait, Veneçuela, Algèria, Angola, Equador, Nigèria, Emirats Àrabs Units, Líbia i Qatar. Aquests països, la majoria dels quals estan en via de desenvolupament, es van rebel·lar el 1973 contra la política de lliure flotació del preu del cru i van actuar en bloc per apujar-ne els preus. La seva actuació va provocar una greu crisi econòmica arreu del món i les economies dels països desenvolupats, molt dependents de l’anomenat or negre, van tremolar però es van curar en salut mitjançant la posada en pràctica de polítiques d’estalvi energètic i el desenvolupament d’energies alternatives com la nuclear o l’eòlica. A aquesta reducció de la demanda mundial de petroli impulsada pels països rics es van sumar els problemes interns de l’OPEP per coordinar les seves actuacions, de manera que avui en dia aquesta organització, que era molt influent en l’economia mundial, no té el poder que tenia abans.»
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96. Many coastal wetlands, for example coral reefs, beaches, salt marshes, and mangrove communities, provide significant coastal protection and thus contribute substantially to the resilience of coastal systems. However, many of these are also identified as being sensitive to accelerated sea level rise. Areas identified as sensitive to accelerated sea level rise in the Second Assessment Report of the IPCC (Bijlsma et al 1996) included low-elevation coral atolls and reef islands, as well as low-lying deltaic, coastal plain and barrier coasts, and their associated wetland habitats (i.e. beaches, estuaries, lagoons, salt marshes, mangroves). Nichols et al (1999) project that coastal wetlands in the Mediterranean, the Baltic, and to a lesser extent along the Atlantic coast of Central and North America and the smaller islands of the Caribbean will be under threat if not lost due to future sea level rises.
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