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Modelling the compressive mechanical behaviour of granite and sandstone historical building stones

Marques, M. Ludovico; Chastre, C.; Vasconcelos, Graça
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 20/12/2012 ENG
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Building stones, particularly sandstone and granite, are very important in the building elements of Portugal’s historical and cultural heritage. Experimental research, based on uniaxial compressive tests, was carried out on selected representative samples of lithotypes of rocks used in historic built heritage, with a view to evaluating the compressive mechanical behaviour of different building stones. The results showed that porosity plays a central role in the compressive behaviour of granites and sandstones. As porosity can be evaluated in field conditions with non-destructive tests it was decided to derive an analytical model to predict compressive behaviour based on the knowledge of porosity of the building stones. A cubic polynomial function was adopted to describe the pre-peak regime under compression to implement the model. Furthermore, a statistical correlation between mechanical and porosity data had to be defined. Good agreement between experimental and analytical compressive stress–strain diagrams, from which the mechanical properties like compressive strength and modulus of elasticity can be derived, was achieved.

Faunistic survey of sandstone caves from Altinópolis region, São Paulo State, Brazil

Zeppelini Filho,Douglas; Ribeiro,Alexandre Cunha; Ribeiro,Guilherme Cunha; Fracasso,Maria Paula Aguiar; Pavani,Marcelo Monetti; Oliveira,Otto Müller Patrão; Oliveira,Sérgio Adriano de; Marques,Antonio Carlos
Fonte: Museu de Zoologia da Universidade de São Paulo Publicador: Museu de Zoologia da Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
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The fauna of eight sandstone caves of the region of Altinópolis, (Serra Geral Arenitic Speleological province, São Paulo State, Southeastern Brazil) was surveyed. Our results improve the previous faunistic knowledge of the region, recording 15 new occurrences for Brazilian caves and 26 for Brazilian sandstone caves. The fauna is characterized by a large number of detritivores/omnivores such as crickets and cockroaches, and several predators like spiders and heteropterans in bat guano.

Spatial distribution of epibenthic molluscs on a sandstone reef in the Northeast of Brazil

Martinez,AS.; Mendes,LF.; Leite,TS.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2012 EN
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The present study investigated the distribution and abundance of epibenthic molluscs and their feeding habits associated to substrate features (coverage and rugosity) in a sandstone reef system in the Northeast of Brazil. Rugosity, low coral cover and high coverage of zoanthids and fleshy alga were the variables that influenced a low richness and high abundance of a few molluscan species in the reef habitat. The most abundant species were generalist carnivores, probably associated to a lesser offer and variability of resources in this type of reef system, when compared to the coral reefs. The results found in this study could reflect a normal characteristic of the molluscan community distribution in sandstone reefs, with low coral cover, or could indicate a degradation state of this habitat if it is compared to coral reefs, once that the significantly high coverage of fleshy alga has been recognized as a negative indicator of reef ecosystems health.

Population Genetic Structure of a Sandstone Specialist and a Generalist Heath Species at Two Levels of Sandstone Patchiness across the Strait of Gibraltar

Gil-López, Manuel Jesús; Segarra-Moragues, José Gabriel; Ojeda, Fernando
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/05/2014 EN
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Many habitat specialist species are originally composed of small, discontinuous populations because their habitats are naturally fragmented or patchy. They may have suffered the long-term effects of natural patchiness. Mediterranean heathlands, a representative habitat in the Strait of Gibraltar region, are associated with nutrient-poor, acidic sandstone soils. Sandstone soil patches in the African side of the Strait (Tangier) are, in general, smaller and more scattered than in the European side (Algeciras). In this study, we analyze the effect of this sandstone patchiness on the population genetic diversity and structure of two Erica species from these Mediterranean heathlands that differ in their edaphic specificity, E. australis, sandstone specialist, and E. arborea, generalist. Average levels of within-population genetic diversity and gene flow between populations were significantly lower in Tangier (high sandstone patchiness) than in Algeciras (low patchiness) for the sandstone specialist, whereas no differences between both sides of the Strait were detected in the edaphic generalist. Since most endemic species in Mediterranean heathlands of the Strait of Gibraltar are sandstone specialists, these results highlight an increased vulnerability to loss of genetic diversity and local extinction of the heathland endemic flora in the Tangier side of the Strait of Gibraltar.

The sedimentology of the lower Silurian whirlpool sandstone in subsurface Lake Erie, Ontario

Johnson, Michael Fergus.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
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The lower Silurian Whirlpool Sandstone is composed of two main units: a fluvial unit and an estuarine to transitional marine unit. The lowermost unit is made up of sandy braided fluvial deposits, in shallow valleys, that flowed towards the northwest. The fluvial channels are largely filled by cross-bedded, well sorted, quartzose sands, with little ripple crosslaminated or overbank shales. Erosionally overlying this lower unit are brackish water to marine deposits. In the east, this unit consists of estuarine channels and tidal flat deposits. The channels consist of fluvial sands at the base, changing upwards into brackish and tidally influenced channelized sandstones and shales. The estuarine channels flowed to the southwest. Westwards, the unit contains backbarrier facies with extensive washover deposits. Separating the backbarrier facies from shoreface sandstone facies to the west, are barrier island sands represented by barrier-foreshore facies. The barrier islands are dissected by tidal inlets characterized by fining upward abandonment sequences. Inlet deposits are also present west of the barrier island, abandoned by transgression on the shoreface. The sandy marine deposits are replaced to the west by carbonates of the Manitoulin Limestone. During the latest Ordovician...

Section XII, 2F, 5 - Murchison District. Dhoornee of Sandstone.

Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Formato: 10 p.
Publicado em 22/03/2013
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Native vocabulary compiled by Dhoornee, Ngadain, Kalagurda, Manya of Ngangara, Sandstone Magisterial District

Cambrian and Ordovician Stratigraphy and Oil and Gas Possibilities in Indiana

Gutstadt, Allan M.
Fonte: Indiana Geological Survey Publicador: Indiana Geological Survey
Tipo: Relatório Formato: 2984602 bytes; application/pdf
EN_US
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Indiana Geological Survey Bulletin 14; Cambrian and Ordovician rocks throughout most of Indiana are subdivided in ascending order as follows: lower part of the St. Croixan series, consisting of the Mt. Simon sandstone and the Eau Claire formation, upper part of the St. Croixan series and the Canadian series consisting of the Knox dolomite; the Chazyan series consisting of the St. Peter sandstone and the Joachim dolomite; the Mohawkian series consisting of the Black River limestone and the Trenton limestone; and the Cincinnatian series consisting of the Eden group (undifferentiated) and the Maysville-Richmond group (undifferentiated). The Mt. Simon sandstone, the Eau Claire formation and the lower part of the Knox dolomite may be facies that represent contemporaneous environments, respectively, of beach or littoral deposition, near-shore deposition, and offshore deposition. The St. Peter sandstone, was deposited unconformably on the eroded surface of the Knox and was succeeded by carbonate deposition until late Ordovician time. The Cincinnatian series represents shallow-water deposition where the physical and biological environments alternated rapidly between clear water and optimum conditions for life and muddy water and unfavorable conditions for life. The Mt. Simon sandstone and the Eau Claire formation are virtually untested for oil and gas...

Depth Relationships in Porosity and Permeability in the Mount Simon Sandstone (Basal Sand) of the Midwest Region: Applications for Carbon Sequestration

Medina, Cristian R.; Barnes, David A.; Rupp, John A.
Fonte: Universidade de Indiana Publicador: Universidade de Indiana
Tipo: Conferência ou Objeto de Conferência Formato: 4833209 bytes; application/pdf
EN_US
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This poster was presented at the 2008 Annual Meeting of the American Association of Petroleum Geologists (AAPG) and the Society of Petroleum Engineers (SPE), held in Pittsburgh, Pennsylvania, from October 11-15, 2008.; Porosity and permeability values collected from core analyses in the Upper Cambrian Mount Simon sandstone indicate a predictable relationship with depth owing to diagenetic changes in the pore structure. This predictive relationship is useful for evaluating the geological carbon sequestration capacity in the Midwestern region. Porosity logs from wells in the study area provide additional sources of petrophysical data. The regional trend of decreasing porosity with depth is described by the equation: φ(d) = 16.36 * e-0.00012*d (r2=0.41), where φ equals porosity and d is depth in feet. The correlation between burial depth and porosity can help predict the petrophysical character of the Mount Simon sandstone in more deeply buried and largely undrilled portions of the basin. Understanding the relationship among porosity, permeability, and depth also provides information for use in numerical models that simulate supercritical carbon dioxide flow within the Mount Simon sandstone. The decrease of porosity and permeability with depth generally holds true on a basinwide scale. However...

An estimate of carbon dioxide storage capacity in the Upper Cambrian basal sandstone of the Midwest region

Medina, Cristian R.; Rupp, John A.
Fonte: Universidade de Indiana Publicador: Universidade de Indiana
Tipo: Conferência ou Objeto de Conferência
EN_US
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This poster was presented at the 8th Annual Conference on Carbon Capture and Sequestration, May 4-7, 2009 Pittsburgh, Pennsylvania.; Porosity values collected from core analyses and geophysical logs from the Upper Cambrian Mount Simon Sandstone in the western part of the Midwest Regional Carbon Sequestration Partnership (MRCSP) region indicate a predictable decrease in porosity with depth. Using this relationship and the methodology of the Carbon Sequestration Atlas of the United States and Canada, we have estimated the potential geologic storage capacity of CO2 in this deep saline aquifer. The storage capacity is a function of the area being assessed, the porosity and gross thickness of the stratigraphic unit, and the CO2 storage efficiency factor, which accounts for reservoir continuity, effective porosity, and the level of certainty of characterization. Our calculations include different scenarios for CO2 storage capacity, which is highly sensitive to changes in the subsurface properties. The porosity and thickness of the deep saline aquifer were used to calculate net porosity feet by using the regional trend of decreasing porosity (φ) with depth relationship (d, in feet) [φ (d) = 16.36 * e-0.00012*d; r2=0.41]. To evaluate the applicability of this relationship...

Characterization of diagenesis and porosity in the Mount Simon Sandstone in the Illinois Basin: Implications for a regional CO2 sequestration reservoir

Ochoa, R.; Bowen, B. B.; Rupp, J. A.
Fonte: Universidade de Indiana Publicador: Universidade de Indiana
Tipo: Conferência ou Objeto de Conferência
EN_US
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This poster was presented at the American Association of Petroleum Geologists (AAPG) meeting, June 7-10, 2009, Denver, Colorado.; The Cambrian Mount Simon Sandstone has been targeted as an important geologic reservoir for carbon dioxide sequestration in the Illinois Basin and throughout the Midwest region. Given its presumed reservoir quality, proximity to underlying Precambrian crystalline basement, and the suitability of the overlying Eau Claire Formation as a confining unit, the Mount Simon may serve as a high capacity, spatially extensive reservoir that is ideal for long term sequestration of injected CO2. However, details of the controls on spatial changes in petrophysical characteristics of this reservoir including the nature of the porosity and authigenic mineralogy are not well understood. These factors have important implications on the effectiveness of the storate capacity, injectivity, and security of the Mount Simon as a sequestration reservoir. Previous studies have suggested an exponential decrease in porosity from over 40% near the surface to less than 1% at the maximum depths of 15,000 ft. However, at mid-level depths, where carbon dioxide injection is most plausible, porosity varies over nearly that entire range, suggesting more complex controls beyond simple compaction on porosity. The loss and formation of porosity in the Mount Simon is a result of a complex history of both physical and chemical digenesis that varies with depositional facies and subsequent groundwater chemistries. Mount Simon core samples representative of varying formation thicknesses and depths in the Illinois Basin were examined petrographically and mineralogically to characterize authigenic minerals and diagenetic textures...

Carbon Dioxide Storage Capacity in the Upper Cambrian Basal Sandstone of the Midwest Region: A County-Based Analysis

Medina, Cristian R.; Rupp, John A.
Fonte: Universidade de Indiana Publicador: Universidade de Indiana
Tipo: Conferência ou Objeto de Conferência
EN_US
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37.37%
This poster was presented at the 2009 Eastern Section Meeting of the American Association of Petroleum Geologists (AAPG) in Evansville, Ind., from Sept 20-22, 2009.; Porosity values collected from core analyses and geophysical logs from the Upper Cambrian Mount Simon Sandstone in the Midwest Regional Carbon Sequestration Partnership (MRCSP) region indicate a predictable decrease in porosity with depth that is best described by the relationship φ (d, in feet) = 16.36 * e-0.00012*d (r2=0.41). This relationship and the Mt. Simon’s thickness were used to calculate net porosity feet, which was incorporated into the methodology presented in the Carbon Sequestration Atlas of the United States and Canada for estimating the potential storage capacity of CO2 in deep saline aquifers. The variables that affect the volumetric calculations include: 1) the area that defines the region being assessed (county by county assessment in this study); 2) the mean porosity of the stratigraphic unit; 3) the gross thickness of the basal sandstone; and 4) the CO2 storage efficiency factor, which accounts for material properties, including reservoir continuity and effective porosity. We conducted a sensitivity analysis to create two scenarios for CO2 storage capacity...

Series 14, 2 - Sandstone district

Bates, Daisy
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Artigo de Revista Científica Formato: 2 p.
Publicado em 27/10/2015
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"Extracts from notebooks 1900 – 1935 when in residence at various camps or travelling...": Sandstone district, Sandstone camp: gave rations to (list follows) Mt Magnet people; names of local tribes.; The Barr Smith Library recognises the moral rights of Aboriginal and Torres Strait Islander peoples as the owners of their knowledge. To this end, Special Collections is digitising the Daisy Bates Papers in our collections to enhance access for people who cannot travel to Adelaide. Please be aware that this site may contain sensitive information, including the names and images of people who have passed away and which may sadden and distress some Aboriginal people. This site may also contain language and terms used by an author that reflect an inappropriate attitude due to the historical context in which these records were created.

Erskine Sandstone Formation: a provenance and geochronological study within the Fitzroy Trough, Western Australia

Thomas, M. C.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012 EN
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37.51%
The Erskine Sandstone Formation is located in the Fitzroy Trough, within the northern Canning Basin, Western Australia. The provenance evolution of the onshore Triassic sandstone of the Erskine Sandstone Formation has not previously been researched. Field work was conducted predominantly at two areas, the Erskine Range, the type section of the Sandstone, and the May River outcrops which include the Pinnacle Rock outcrop. Field work in the area showed a transitional boundary between the underlying Blina Shale and the Erskine Sandstone Formation making identification of the boundary zones difficult. Through the use of U-Pb zircon analysis on samples taken from the Erskine Range and the May River, this study suggests the two outcrops have differing sources. Samples taken from the Erskine Range contain Permian aged sediments which are not present in the May River samples. The significant presence of Mesoproterozoic sediments in the May River samples which are not reflected in the Erskine Range samples further suggests different sources. The large presence of Palaeoproterozoic sediments in both the Erskine Range and the May River outcrops suggests the uranium rich King Leopold Ranges is a possible source. These sediments, combined with the presence of reductants in the Erskine Sandstone Formation suggest the possibility of sandstone-hosted uranium mineralisation within the Fitzroy Trough. Other possible sediment sources include the Musgrave Block and Arunta Inlier...

Hydrogeology of the Pilliga sandstone aquifer in the western Coonamble embayment and its implications for water resource management

Wolfgang, Carolann
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN_AU
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Water resources in Australia are undergoing the greatest changes since Federation. The Council of Australian Governments' (COAG) 1995 Water Reforms had two control themes, the need for pricing mechanisms to reflect the true costs of supplying water and the need to better balance water allocation between consumers and the environment. These, coupled with the Murray-Darling Basin Ministerial Council's 1995 Cap on diversions of surface water in the Basin at 1994 levels have placed pressures on water resources, particularly groundwater. In the New South Wales (NSW) part of the Basin, water has been over-allocated by 150%. The pressures on water are exemplified in the lower catchments of the Bogan-Macquarie and Castlereagh River where highly profitable cotton irrigators compete with graziers and the internationally important RAMSAR wetland, the Macquarie Marshes. In this area, which forms the Coonamble Embayment of the Great Artesian Basin (GAB), groundwater is also used for both irrigation and town water supplies. Within the Embayment, the Pilliga Sandstone aquifer is the important artesian freshwater aquifer. This study seeks to characterise the Pilliga Sandstone aquifer. Recent work has produced a general model of the GAB that in the Coonamble Embayment suggests recharge of the Pilliga Sandstone in the south and eastern portions of the Embayment with groundwater movement towards the north and north-west...

Sandstone weathering processes damaging prehistoric rock paintings at the Albarracín Cultural Park, NE Spain

Benito, Gerardo; Machado, María José; Sancho, C.
Fonte: Springer Publicador: Springer
Tipo: Artículo Formato: 579917 bytes; image/jpeg
ENG
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The rock paintings in cliff-foot caves of the Albarracin Cultural Park are known as some of the most important evidences of the Levantine prehistoric art of Spain (8000–3000 BP). The paintings are on sandstone (Buntsandstein facies) of Triasic age, which may develop intense weathering. The analysis of the variables controlling the weathering indicate that salt and wetting-drying weathering are responsible for granular disintegration and flaking, which lead to rock painting deterioration.; This study was supported by a grant of the Albarracin Town Council and the Instituto de Estudios Turolenses; Peer reviewed

Sandstone petrofacies in the northwestern sector of the Iberian Basin; Petrofacies arenosas en el sector noroccidental de la Cuenca Ibérica

Arribas, J.; Ochoa, M.; Mas, R.; Arribas, Mª E.; González-Acebrón, L.
Fonte: Universidad Complutense de Madrid Publicador: Universidad Complutense de Madrid
Tipo: Artículo Formato: 4013523 bytes; application/pdf
ENG
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[EN] During the most active rifting stages in the northwestern sector of the Iberian Basin (Cameros Basin and Aragonese Branch of the Iberian Range), thick sequences of continental clastic deposits were generated. Sandstone records from Rift cycle 1 (Permo-Triassic) and Rift cycle 2 (Late Jurassic-Early Cretaceous) show similarities in composition. Based on the most recent data, this paper describes sandstone petrofacies developed during both rifting periods. Six petrofacies can be distinguished: two associated with Rift cycle 1 (PT-1 and PT-2) and four with Rift cycle 2 (JC-1 to JC-4). All six petrofacies can be classifi ed as sedimentoclastic or plutoniclastic. Sedimentoclastic petrofacies developed during early rifting stages either through the recycling of pre-rift sediments or signifi - cant palaeogeographical changes. These facies comprise a thin succession (<100 m) of clastic deposits with mature quartzose and quartzolithic sandstones containing sedimentary and metasedimentary rock fragments. Carbonate diagenesis is more common than clay mineral diagenesis. Sedimentoclastic petrofacies have been identifi ed in Rift cycle 1 (Saxonian facies, PT-1) and Rift cycle 2 (JC-1 and JC-3; Tithonian and Valanginian, respectively). In the absence of the pre-rift sedimentary cover...

The Paleozoic-Mesozoic recycling of the Rakaia Terrane, South Island, New Zealand: sandstone clast and sandstone petrology, geochemistry, and geochronology

Wandres, Anekant; Bradshaw, John D; Ireland, Trevor
Fonte: Sir Publishing Publicador: Sir Publishing
Tipo: Artigo de Revista Científica
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The Torlesse terranes - part of the New Zealand Eastern Province - are accretionary complexes that comprise an enormous volume of quartzofeldspathic sandstones and mudstones with subsidiary conglomerates plus minor oceanic assemblages. Two terranes are recognised in the South Island - the Permian to Late Triassic Rakaia Terrane and the Late Jurassic to Early Cretaceous Pahau Terrane. Sandstone clasts from two Rakaia Terrane and two Pahau Terrane conglomerates were collected. We present the first combined detailed information on petrography and geochemistry of Torlesse conglomerate sandstone clasts and use our own and published U-Pb SHRIMP detrital zircon age data to demonstrate the recycling of the Rakaia Terrane into Rakaia strata itself and into Pahau Terrane strata. Sandstone clast maj or and trace element chemical data largely support petrographic observations derived from thin-section analysis. The similarities of petrographic and geochemical data between sandstone clasts from the Rakaia Terrane and Rakaia sandstones suggest that clasts in the Permian Te Moana and Late Triassic Lake Hill Conglomerates were derived by autocannibalistic reworking of older, consolidated, Rakaia sediments. Data from sandstone clasts from the Pahau Terrane suggest that uplift of the Rakaia Terrane continued into the Cretaceous. These Pahau Terrane clasts indicate that at the time of the Pahau sedimentation Permian to early Late Triassic Rakaia rocks were exposed and recycled into the Pahau Basin.

Combined single-grain (U-Th)/He and U/Pb dating of detrital zircons from the Navajo Sandstone, Utah

Rahl, Jeffrey; Reiners, Peter; Campbell, Ian; Nicolescu, Stefan; Allen, Charlotte M
Fonte: Geological Society of America Inc Publicador: Geological Society of America Inc
Tipo: Artigo de Revista Científica
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Radioisotopic dating of detrital minerals in sedimentary rocks can constrain sediment sources (provenance), elucidate episodes and rates of ancient orogenesis, and give information on paleogeography and sediment-dispersal patterns. Previous approaches have been restricted to the application of a single technique, such as U/Pb or fission-track dating, to detrital grains. These methods provide crystallization and cooling ages, respectively, of sediment sources (terranes). However, evidence for source regions from a single technique can be ambiguous because candidate source terranes often have similar ages for a given radioisotopic system. This ambiguity can be avoided by applying multiple radioisotopic systems to individual detrital grains. Here we present a method for measuring both (U-Th)/He and U/Pb ages of single crystals of detrital zircon, providing both formation and cooling ages (through ∼ 180 °C). We applied this technique to zircons from the Lower Jurassic Navajo Sandstone, which represents one of the largest erg deposits in the geologic record. A large fraction of these zircons was derived from crust that formed between 1200 and 950 Ma, but cooled below ∼ 180 °C ca. 500-250 Ma. This history is characteristic of Grenvillian-age crust involved in Appalachian orogenesis (and subsequent rifting) in eastern North America. Our finding requires the existence of a transcontinental sediment-dispersal system capable of moving a large volume of detritus westward (modern coordinates) throughout the late Paleozoic and early Mesozoic.

Faunistic survey of sandstone caves from Altinópolis region, São Paulo State, Brazil

Zeppelini Filho, Douglas; Ribeiro, Alexandre Cunha; Ribeiro, Guilherme Cunha; Fracasso, Maria Paula Aguiar; Pavani, Marcelo Monetti; Oliveira, Otto Müller Patrão; Oliveira, Sérgio Adriano de; Marques, Antonio Carlos
Fonte: Universidade de São Paulo. Museu de Zoologia Publicador: Universidade de São Paulo. Museu de Zoologia
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 01/01/2003 ENG
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37.19%
A fauna de oito cavernas areníticas da região de Altinópolis (província espeleológica arenítica da Serra Geral, Estado de São Paulo, Sudeste do Brasil) foi amostrada. Nossos resultados aumentaram o conhecimento faunístico prévio da região, com o registro de 15 novas ocorrências para cavernas brasileiras e 26 para cavernas brasileiras em arenito. A fauna é caracterizada por um grande número de detritívoros/carnívoros tais como grilos e baratas, diversos predadores tais como aranhas e heterópteros no guano de morcego.; The fauna of eight sandstone caves of the region of Altinópolis, (Serra Geral Arenitic Speleological province, São Paulo State, Southeastern Brazil) was surveyed. Our results improve the previous faunistic knowledge of the region, recording 15 new occurrences for Brazilian caves and 26 for Brazilian sandstone caves. The fauna is characterized by a large number of detritivores/omnivores such as crickets and cockroaches, and several predators like spiders and heteropterans in bat guano.

Petrography and geochemistry of Ahwaz Sandstone Member of Asmari Formation, Zagros, Iran: implications on provenance and tectonic setting

Jafarzadeh,Mahdi; Hosseini-Barzi,Mahboobeh
Fonte: Instituto de Geología, UNAM Publicador: Instituto de Geología, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2008 EN
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An integrated petrographic and geochemical study of the Ahwaz Sandstone Member ofOligocene-Miocene age, Asmari Formation in Zagros, southwest Iran, was carried out to infer their provenance and tectonic setting. This study is based on the analysis of core samples from three subsurface sections (wells Az-85, Az-11, andAz-89) in Ahwaz oilfield in the Dezful embayment subzone. On the basis of the framework composition (point counting) and whole-rock geochemistry (major elements), the sandstones are classified as quartzarenite, sublitharenite, and subarkose types. Petrographic studies reveal that these sandstones contain quartz, feldspars and fragments of sedimentary and metasedimentary rocks. The modal analysis data of 50 collected (medium size and well sorted) samples, imply a recycled orogen and craton interior tectonic provenance. Moreover, petrographic point count data indicate quartz-rich sedimentary (recycled), middle to high-grade metamorphic, andplutonic parent rocks for the Ahwaz Sandstone. Tectonic setting discrimination diagrams based on major elements suggest a quarizose sedimentary provenance in a passive continental margin. As indicated by the CIW index (chemical index of weathering) of the Ahwaz Sandstone (average value of 67) their source area underwent "intense" recycling but "moderate" degree of chemical weathering. The petrography and geochemistry results are consistent with a semiarid climate and low-relief highlands.