983 resultados para Geology, Stratigraphic -- Cretaceous -- Catalonia -- Tremp, Conca de
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A new species of terrestrial gastropod - Anadromus penai sp. nov. (Fam. Anadromidae) - is described from a set of composite moulds collected in reddish silts and clays of Campanian-Maastrichtian age, found in the lower pan of the Taveiro Formation (Taveiro, Coimbra, West Central Portugal). The known occurrences of this new species are restricted to the type locality. The main differences from other contemporaneous Anadromidae are the profuse spiral sculpture of the body-whorl, with 20-22 sub-equal, close, and regular ribs.
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A new Lower Cretaceous (Aptian-Albian) dinosaur tracksite at the Olhos de Água beach is described. It is the first vertebrate fossil finding ever found in the concerned unit, and yielded 128 tracks in 17 trackways within an area of ca. 80 square metres. Three tridactyl footprint morphotypes have been recognized: - Type I ("Iguanodontipus-like") - trackways D, F, K, J and P; - Type 2 (large theropod), although larger in size, typically from a Grallator-like theropod footprint, i.e , A, B, G, H and 0 trackways; - Type 3 (medium size theropod); M is the only track of this type. There are other, poorly preserved, unidentified trackways. The theropod, swinging trackway B was produced by an animal that was limping. The theropod track M starts eastwards but drastically changes westwards, speeding up at the same time; this dinosaur decided to turn around and run in the opposite direction. This site shows three main trackway directions: to the South, to the East, and westwards. Except for the trackway 0, large theropods A, B, G and H walked southwards. Perpendicularly to the se, ornithopods, small theropods and unidentified trackmakers walked towards East (5) and West (7). The segregation oftrackmakers and directions, with large theropod traekways southwards and other dinosaurs' west or eastwards, may mean that large theropods patrolled a walkway area to an important resource, most probably water, often frequented by ornithopods and smaller theropods. There is no evidence of social behavior or gregarism: footprints' overposition shows that the large, southwards walking theropods passed on different occasions. Three trackway sequences can be established by chronologic order.
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Mineralogical assemblages, specially clay mineral assemblages, have been widely used in multidisciplinary stratigraphical studies. This paper presents the results obtained in the study of a Lower Cretaceous depositional sequence from the Lusitanian Basin (Portugal). The Upper Hauterivian – Lower Barremian section at Guincho Fort pertains mostly to the Ha7 3rd order depositional sequence defined by J. REY & al. (2003) and has been studied in a detailed bed-by-bed sampling corresponding to a total of 85 samples. The analysis of the obtained clay mineral assemblages has contributed to the paleoenvironmental and paleogeographical reconstruction of the studied interval and has improved the sequence stratigraphic interpretation and positioning of sequence boundaries and other sequential surfaces (transgressive and flooding surfaces).
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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.
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Recent studies have described widespread statigraphic units of Late Pleistocene and Holocene age in the western part of the Amazon Basin. The recognition of deltaic sedimentation in the uppermost these units near Rio Branco, Brazil, at a modern elevation of approximately 500 feett leads to the conclusion that this area was situated on the edge of a large Amazonian lake that existed in the recent past when Andean tectonism caused active downwarping of the western edge of the Amazon Basin. The ramifications of this "Lago Anazonas" hypothesis extend into every area of modern Amazonian geology and biology.
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Our study provides paleontological and geological data substantiating a paleoenvironmental model for the upper Miocene-Pliocene of Southwestern Amazonia. The extensive Late Tertiary sediments of The Solimões Formation, outcropping in Southwestern Amazonia, were deposited by a complex megafan system, originating in the high Peruvian Andes. The megafan system was the sedimentological response to the Andean Quechua tectonic phase of Tertiary age, producing sediments that fdled the foreland basin of Southwestern Amazonia. Occurrences of varied vertebrate fossil assemblages of the Huayquerian-Montehermosan Mammal age collected in these sediments support this interpretation. The fauna includes several genera and species of fishes, reptiles, birds, mammals and appears to be one that could have lived in or near a riverine habitat. In the Late Pliocene, the megafan system became inactive as a result of the influence of the Diaguita Tectonical Phase.
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(1873 printing)
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v. 12 (1843)
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2nd ser. v. 17 (1856)
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v. 15 (1845)
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2nd ser. v. 10 (1852)
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2nd ser. v. 19 (1857)
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2nd ser. v. 15 (1855)