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Rocky shore macroinvertebrates assemblages as indicators of sewage pollution

Oliveira, Joana
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
18.42%
As zonas costeiras estão sujeitas a intensa pressão humana, sendo o enriquecimento orgânico e de nutrientes, com origem em descargas de águas residuais, um dos principais problemas. Atualmente, procurando prevenir a contínua deterioração das zonas costeiras, a comunidade científica tem concentrado esforços na procura de índices e indicadores eficazes. Contudo, de forma a alcançarmos sustentadas ferramentas de gestão, é indispensável, antes do mais, adquirir um conhecimento detalhado das respostas das comunidades biológicas aos diferentes impactos antropogénicos, como o são, por exemplo, as descargas de águas residuais. Nesse sentido, a presente tese como objetivo principal compreender os efeitos daquelas descargas nas comunidades de macroinvertebrados da zona intertidal da costa rochosa, podendo ser dividida em dois pontos principais: no inicial, quisemos estudar os padrões de abundância, riqueza específica, estrutura da comunidade e produção secundária das comunidades de macroinvertebrados expostos a descargas de águas residuais; no segundo, procurou-se comparar as respostas das comunidades intertidais expostas a este foco de perturbação em diferentes bioregiões (Atlântico e Mediterrâneo), por forma a encontrar padrões de resposta semelhantes. O primeiro objetivo desta tese foi explorado no capítulo 2...

Effects of sewage pollution on the structure of rocky shore macroinvertebrate assemblages

Cabral-Oliveira, J.; Mendes, S.; Maranhão, P.; Pardal, M. A.
Fonte: Springer Science Publicador: Springer Science
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
17.56%
The urgency to find efficient indices and indicators to prevent further deterioration of coastal areas is one of the hot topics in today’s scientific publication. However, a detailed knowledge of community responses to anthropogenic impacts is essential to sustain those indices. The studies on the response of benthic community to sewage pollution on intertidal rocky shores are generally based on visual census and do not take into account the tidal levels. In order to fulfil this gap in this study: (i) the sampling was performed by destructive sampling, with all individuals identified to the species level; (ii) the samplingwas done at all levels of the intertidal (sublittoral fringe, eulittoral, and littoral fringe). Sewage pollution changed the environmental variables and the abundance of macroinvertebrates, being Mytilus galloprovincialis, Melarhaphe neritoides, and Chthamalus montagui the species most responsible for the dissimilarities observed. Effects were different on the three intertidal zones: community structure changed in the sublittoral fringe; suspensionfeeders abundances and species richness increased in the eulittoral; no differences were detected in the littoral fringe. Moreover, the results confirm that the presence of sewage discharges tended to benefit suspension feeders...

Identificação e caracterização dos biótopos de uma praia de Peniche

Antunes, Dina Maria Trindade
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
16.86%
A praia do Abalo situa-se na costa oeste de Portugal, na península de Peniche ( 39º21’12,90’’N e 9º23’06,15’’W). De Março de 2007 a Agosto de 2008 foi efectuado um estudo com o objectivo de identificar e caracterizar as comunidades intertidais de subtrato rochoso desta praia. Foi recenseado um total de 105 espécies, das quais 35 de macroalgas, 68 de macroinvertebrados e 2 de líquenes. No que respeita às macroalgas foi a Divisão Rhodophyta que apresentou uma maior riqueza em espécies, com 19, seguida da divisão Chlorophyta com 9 espécies e da Heterokontophyta com 7 espécies. Dentro dos macroinvertebrados foram os moluscos que apresentaram a maior diversidade, com 30 espécies, seguidos dos crustáceos com 16 e dos anelídeos com 13 espécies. A diversidade aumentou da zona superior da praia em direcção à linha de água. Na praia do Abalo identificaram-se dois biótopos: um localizado na franja sublitoral e caracterizado pelas macroalgas Corallina elongata, Halopteris filicina e Asparagopsis armata e outro, localizado no eulitoral superior, caracterizado pelo cirrípede Chthamalus sp, pelo líquen Lichina pygmaea e pelo gastrópode Melaraphe neritoides. Apenas este último biótopo está definido para a região costeira de Inglaterra e Irlanda. Os factores determinantes no estabelecimento das comunidades da zona intertidal rochosa da praia do Abalo...

Caracterização sazonal de uma praia estuarina da Ria de Aveiro : estrutura da comunidade e relações tróficas de espécies seleccionadas

Rodrigues, Clara Lúcia Ferreira
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
18.31%
As praias, devido aos processos físicos e geológicos associados ao ambiente sedimentar, são um dos habitats mais inóspitos para o estabelecimento de comunidades de macroinvertebrados. No entanto, apesar da sua aparente uniformidade e pobreza específica, as praias sedimentares possuem uma fauna marinha de grande diversidade ecológica. A distribuição da macrofauna nestas praias depende de uma série de respostas quer físicas quer biológicas ao ambiente, sendo a zonação um fenómeno bem conhecido nos habitats intertidais. Nas condições relativamente protegidas dos sistemas estuarinos, as zonas intertidais são caracterizadas pela abundância de matéria orgânica e pela presença de cadeias tróficas complexas, onde os macroinvertebrados desempenham um papel fundamental no fluxo de matéria e energia para níveis tróficos superiores. Neste estudo é realizada a caracterização espaciotemporal da comunidade de macroinvertebrados bentónicos e dos parâmetros ambientais numa praia estuarina do Canal de Mira (Ria de Aveiro, NO Portugal), é estimada a produção secundária anual e são determinadas relações tróficas entre algumas das espécies mais importantes. A caracterização espacio-temporal foi efectuada através de uma amostragem aleatória estratificada sazonal (Abril...

Ecology and dynamics of two intertidal algal communities on the littoral of the Island of São Miguel (Azores).

Neto, Ana I.
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Publicado em /08/2000 ENG
Relevância na Pesquisa
18.16%
Copyright © 2000 Kluwer Academic Publishers. Printed in the Netherlands.; The intertidal benthic algal communities of two sites located on opposite coasts of São Miguel Island (Azores), were studied over a 2-year period (September 1993 - September 1995). At both sites (São Roque on the south coast and São Vicente on the north), the littoral region was surveyed from the upper intertidal down to the sublittoral fringe. The survey revealed five distinct zones, with a variable degree of overlapping. The two upper zones were characterized by animals (littorinids and barnacles, respectively). Lower down, algal communities formed three distinct zones: an upper Fucus spiralis/Gelidium microdon association, a more extensive turf zone, and a belt featuring erect or frondose algae. Upper in the eulittoral, the turf was mainly monospecific, and dominated by Caulacanthus ustulatus. The lower eulittoral turf was dominated by articulated coralline algae, the associated species differing between the two sites studied. Mainly erect algae (Pterocladiella, Asparagopsis, etc.) occurred furthest down the shore and extended into the nearby shallow sublittoral. Two intertidal communities were studied at each locality: the upper eulittoral (Caulacanthus turf in São Roque and the Fucus spiralis/Gelidium microdon association at São Vicente)...

The reproductive cycle of Patella candei gomesii Drouët, 1858 (Mollusca: Patellogastropoda), an Azorean endemic subspecies

Curdia, João; Rodrigues, Armindo; Martins, António M. de Frias; Costa, Manuel
Fonte: Balaban, Philadelphia/Rehovot Publicador: Balaban, Philadelphia/Rehovot
Tipo: Artigo de Revista Científica
Publicado em //2005 ENG
Relevância na Pesquisa
16.86%
Copyright © 2005, Taylor & Francis.; Patella candei gomesii is morphologically plastic comprising two ecomorphs. The “smooth limpet” is characteristic of the eulittoral zone, whereas the “fly limpet” is mainly found higher in the shore, on the splash zone of exposed areas. Their reproductive strategies are poorly understood. This study investigated the reproductive cycles of the ecomorphs using histological techniques. The annual cycles were found to be similar. Both sexes exhibited synchronous patterns and were mature most of the year. In April, significant increases were observed in the relative volume occupied by previtellogenic and vitellogenic cells in females, and by spermatogonia, spermatids and spermatocytes in males. The maximum values for mature oocytes and spermatozoa were observed in July. It is concluded that the breeding season of P. candei gomesii lasts the whole year peaking in the summer (when reproductive condition is highest and the main spawning event must occur). The implications of these findings for the taxonomy and conservation of the subspecies are further discussed.

Avaliação do efeito da natureza do substrato em comunidades intertidais

Nogueira, Eunice Rute Magalhães
Fonte: Universidade dos Açores Publicador: Universidade dos Açores
Tipo: Dissertação de Mestrado
Publicado em 10/02/2014 POR
Relevância na Pesquisa
16.86%
Dissertação de Mestrado, Biodiversidade e Biotecnologia Vegetal, 10 de Fevereiro de 2014, Universidade dos Açores.; Hoje em dia a degradação da zona litoral em todo o mundo é cada vez mais visível. As zonas costeiras naturais estão a ser progressivamente substituídas por estruturas artificiais construídas pelo homem para diversos fins, e.g abrandamento da erosão marinha, protecção de estruturas ligadas a actividades marítimas, etc.. Nos países mais desenvolvidos a costa natural está visivelmente a desaparecer e cada vez mais se observam estruturas artificiais que, por sua vez, podem causar distúrbios na biodiversidade costeira de cada zona. Na Ilha de São Miguel, a mais desenvolvida do arquipélago, existe já um número considerável de estruturas artificiais. De alguns anos a esta parte, a investigação sobre o efeito do urbanismo costeiro no sistema natural tem aumentado. Apesar desta tendência, poucos estudos têm‐se centrado nas mudanças na distribuição e abundância de organismos, causadas pela introdução de estruturas feitas pelo homem. Nos Açores só se conhece um estudo realizado na ilha do Pico e que teve por objectivo avaliar o efeito de uma estrutura artificial, construída para diminuir a exposição da costa à acção das ondas...

Characterization of Salt-Regulated Mannitol-1-Phosphate Dehydrogenase in the Red Alga Caloglossa continua1

Iwamoto, Koji; Kawanobe, Hideaki; Ikawa, Tomoyoshi; Shiraiwa, Yoshihiro
Fonte: The American Society for Plant Biologists Publicador: The American Society for Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /10/2003 EN
Relevância na Pesquisa
16.86%
Mannitol-1-phosphate (M1P) dehydrogenase (M1PDH; EC 1.1.1.17), an enzyme catalyzing the reduction of Fru-6-phosphate (F6P) to M1P in algal mannitol biosynthesis, was purified to homogeneity from a cell homogenate of the eulittoral red alga Caloglossa continua (Okamura) King et Puttock. The enzyme was a monomer with an apparent molecular mass of 53 kD, as determined by gel filtration and SDS-PAGE, and exhibited an pI of approximately 5.5. The substrate specificity was very high toward F6P and M1P for respective reductive and oxidative reactions. The enzyme was found to be a sulfhydryl-type, because its activity was inhibited by N-ethylmaleimide and p-hydroxymercuribenzoate, and the inhibition by p-hydroxymercuribenzoate was rescued by 2-mercaptoethanol. Some unknown factors in the extract may also have inhibited the activity, because the total activity was greatly increased through the purification procedure. The optimum pH for F6P reduction was changed from 6.0 or lower to 7.2 by the addition of 200 mm NaCl. The reduction of F6P showed strong substrate inhibition above 0.5 mm. However, Km(F6P) of M1PDH was increased eight times by the addition of 200 mm NaCl, whereas Vmax was in a similar range with the avoidance of substrate inhibition by F6P. These results indicate that the enzyme was finely and directly regulated by the salt concentration without the requirement for gene expression. M1PDH can therefore be a key enzyme for regulating mannitol biosynthesis when the alga is stressed by a salinity change.

Physiological Responses in a Variable Environment: Relationships between Metabolism, Hsp and Thermotolerance in an Intertidal-Subtidal Species

Dong, Yun-wei; Yu, Shan-shan; Wang, Qing-lin; Dong, Shuang-lin
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 17/10/2011 EN
Relevância na Pesquisa
16.86%
Physiological responses to temperature reflect the evolutionary adaptations of organisms to their thermal environment and the capability of animals to tolerate thermal stress. Contrary to conventional metabolism theory, increasing environmental temperatures have been shown to reduce metabolic rate in rocky–eulittoral-fringe species inhabiting highly variable environments, possibly as a strategy for energy conservation. To study the physiological adaptations of an intertidal-subtidal species to the extreme and unpredictable heat stress of the intertidal zone, oxygen consumption rate and heat shock protein expression were quantified in the sea cucumber Apostichopus japonicus. Using simulate natural temperatures, the relationship between temperature, physiological performance (oxygen consumption and heat shock proteins) and thermotolerance were assessed. Depression of oxygen consumption rate and upregulation of heat shock protein genes (hsps) occurred in sequence when ambient temperature was increased from 24 to 30°C. Large-scale mortality of the sea cucumber occurred when temperatures rose beyond 30°C, suggesting that the upregulation of heat shock proteins and mortality are closely related to the depression of aerobic metabolism...

Resistance to fresh and salt water in intertidal mites (Acari: Oribatida): implications for ecology and hydrochorous dispersal

Pfingstl, Tobias
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.86%
The resistance to fresh water and seawater in three intertidal oribatid mite species from Bermuda, Alismobates inexpectatus, Fortuynia atlantica and Carinozetes bermudensis, was tested in laboratory experiments. Larvae are more sensitive to fresh and salt water, nymphs and adults showed equal tolerances. Fortuynia atlantica and A. inexpectatus were more resistant to salt water whereas C. bermudensis survived longer in fresh water. Differences in the resistance to fresh and salt water among the three species may be related to their different vertical occurrences in the eulittoral zone but also to the ability of single species to dwell in periodically brackish waters. In all three species half of the specimens survived at least 10 days in fresh water and more than 18 days in salt water. Maximal submersion time in fresh and salt water ranged from 40 to 143 days. Based on median lethal times it could be estimated that each species would be able to survive transport in seawater along the Gulf Stream over a distance of 3,000 km, from Central America to Bermuda. Thus hydrochorous dispersal should be assumed as the most likely mode of dispersal in intertidal fortuyniid and selenoribatid mites.

Biotopos marinos intermareales entre Canal Trinidad y Canal Smyth, Sur de Chile

Soto, Eulogio H.; Báez, Pedro; Ramírez, María E.; Letelier, Sergio; Naretto, Javier; Rebolledo, Andrea
Fonte: Universidad de Valparaíso. Facultad de Ciencias del Mar Publicador: Universidad de Valparaíso. Facultad de Ciencias del Mar
Tipo: Artículo de revista
ES
Relevância na Pesquisa
16.86%
Indexación: Scielo; Durante un crucero oceanográfico realizado entre el sector sur de la región de Aysén y sector norte de Magallanes, Canal Trinidad a Canal Smyth (50º00'S,75º00'W a 52º00'S, 73º48'W), sur de Chile, se efectuaron 13 estaciones de recolección de material biológico para registrar y caracterizar los biotopos del intermareal rocoso del área. Se identificaron 19 biotopos, 12 de los cuales eran biotopos reconocidos para otras áreas más septentrionales de Aysén; 6 correspondían a variantes de los anteriores y uno sólo fue reconocido y descrito como biotopo nuevo. Entre los primeros están los biotopos de litoral rocoso correspondientes a las especies dominantes Bostrychia harveyi, Acrosiphonia pacifica, Porphyra sp., Adenocystis utricularis, Iridaea tuberculosa y Mazzaella laminarioides-Nothogenia fastigiata. Entre los 6 que representaban variantes de algunos de los biotopos anteriormente descritos hubo 2 de Porphyra sp., 3 de Bostrychia harveyi y 1 de Mazzaella laminarioides-Nothogenia fastigiata. Sólo el biotopo de litoral rocoso integrado por la macroalga Caepidium antarcticum y algas coralináceas crustosas, constituyeron un biotopo nuevo para el área que se distribuye en la subzona eulitoral inferior de frentes protegidos y se caracteriza por presentar una fuerte influencia subantártica. La diversidad de biotopos costeros fue alta...

Distribuição geográfica da fauna e flora da Baía de Guanabara

Oliveira,Lejeune P. H. de
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/1947 PT
Relevância na Pesquisa
17.56%
The author studied, the horizontal and vertical distribution of most common part of the flora and fauna of the bay of Guanabara at Rio de Janeiro. In this paper the eulittoral, poly, meso and oligohaline regions were localised and studied; and the first chart of its distribution was presented (fig. 2). The salinity of superficial waters was established through determinations based on 30 trips inside the buy for collecting biological materials. Some often 409 determinations which were previous reported together with the present ones served for the eleboration of a salinity map of the bay of Guanabara (fig. 1). This map of fig. 2 shows the geographic locations of the water regions. EULITTORAL WATER REGIME — Fig. 3 shows the diagram scheme of fauna and flora of this regime. Sea water salinity 34/1.000, density mean 1.027, transparent greenish waters, sea coast with moderate bursting waves. Limpid sea shore with white sand, gneiss with the big barnacle Tetraclita squamosa var. stalactifera (Lam. Pilsbry. Vertical distributions: barna¬cles layers with a green region in which are present the oyster Ostrea pa-rasitica L., the barnacles Tetraclita, Chthamalus, Balanus tintinnabulum var. tintinnabulum (L.) e var. antillensis Pilsbry in connection with several mollusca and the sea beatle Isopoda Lygia sp. Covered by water and exposed to air by the tidal ritms...

Non-climatic thermal adaptation: implications for species' responses to climate warming

Marshall, David J.; McQuaid, Christopher D.; Williams, Gray A.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.86%
There is considerable interest in understanding how ectothermic animals may physiologically and behaviourally buffer the effects of climate warming. Much less consideration is being given to how organisms might adapt to non-climatic heat sources in ways that could confound predictions for responses of species and communities to climate warming. Although adaptation to non-climatic heat sources (solar and geothermal) seems likely in some marine species, climate warming predictions for marine ectotherms are largely based on adaptation to climatically relevant heat sources (air or surface sea water temperature). Here, we show that non-climatic solar heating underlies thermal resistance adaptation in a rocky–eulittoral-fringe snail. Comparisons of the maximum temperatures of the air, the snail's body and the rock substratum with solar irradiance and physiological performance show that the highest body temperature is primarily controlled by solar heating and re-radiation, and that the snail's upper lethal temperature exceeds the highest climatically relevant regional air temperature by approximately 22°C. Non-climatic thermal adaptation probably features widely among marine and terrestrial ectotherms and because it could enable species to tolerate climatic rises in air temperature...

Warming reduces metabolic rate in marine snails: adaptation to fluctuating high temperatures challenges the metabolic theory of ecology

Marshall, David J.; McQuaid, Christopher D.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.86%
The universal temperature-dependence model (UTD) of the metabolic theory of ecology (MTE) proposes that temperature controls mass-scaled, whole-animal resting metabolic rate according to the first principles of physics (Boltzmann kinetics). Controversy surrounds the model's implication of a mechanistic basis for metabolism that excludes the effects of adaptive regulation, and it is unclear how this would apply to organisms that live in fringe environments and typically show considerable metabolic adaptation. We explored thermal scaling of metabolism in a rocky-shore eulittoral-fringe snail (Echinolittorina malaccana) that experiences constrained energy gain and fluctuating high temperatures (between 25°C and approximately 50°C) during prolonged emersion (weeks). In contrast to the prediction of the UTD model, metabolic rate was often negatively related to temperature over a benign range (30–40°C), the relationship depending on (i) the temperature range, (ii) the degree of metabolic depression (related to the quiescent period), and (iii) whether snails were isolated within their shells. Apparent activation energies (E) varied between 0.05 and −0.43 eV, deviating excessively from the UTD's predicted range of between 0.6 and 0.7 eV. The lowering of metabolism when heated should improve energy conservation in a high-temperature environment and challenges both the theory's generality and its mechanistic basis.

Benthic Community zonation in a breakwater on the north coast of the state of Rio de Janeiro, Brazil

Masi,Bruno Pereira; Macedo,Isabela Maria; Zalmon,Ilana Rosental
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
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The present study presents the vertical zonation pattern of the intertidal benthic organisms on granitic boulders in the Farol de São Tomé beach (22º02'S, 41º03'W), Rio de Janeiro State. Four sampling profiles using 20 x 20 cm quadrats through a photo quadrat technique revealed four horizontal bands: (1) Littoral Fringe characterized by empty space and Littorina; (2) Upper eulittoral mainly occupied by Chthamalus and bare rock; (3) Lower eulittoral characterized by Chthamalus, Phragmatopoma, Ulva and Centroceras; and (4) Sublittoral Fringe characterized by Ulva, Phragmatopoma and Hypnea. The high variability in the relative abundance of the dominant species among the profiles may be attributed to the high topographic irregularity, reflecting in different wave action intensity at the same height, and consequently favoring the establishment of different species. The frequent substrate alternation from granitic rock to Phragmatopoma sandy reefs might contribute to the small-scale spatial variability. The implantation of a breakwater on an area without natural rocky shores allowed the study of intertidal benthic communty zonation, and provide a baseline for the experimental studies.

The Middle Paleolithic of Murcia

Zilhão, João; Villaverde, Valentín
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2008 ENG
Relevância na Pesquisa
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Thirty-six Middle Paleolithic sites are currently known in Murcia. The open air localities correspond to patches or scatters in surficial position, with one cluster of four sites in the Yecla plateau suggesting that, where flint is concerned, a simple model of reduction-with-distance to source underlies inter-assemblage variability. Five stratified cave and rockshelter sites show logistical use with a fragmentary representation of the flint production chain and transport of curated items over significant distances. The coastal sites document the exploitation of eulittoral shellfish as a food resource. The associated human remains are of Neandertals, with evidence for their survival to at least 34.5 ka 14C BP at Sima de las Palomas.; Hi ha 36 jaciments del paleolític mitjà coneguts a la regió de Múrcia. Els jaciments a l’aire lliure són tots de superfície. Una concentració en els altiplans de Yecla indica que, per al cas del sílex, la variabilitat industrial observada pot explicar-se a través d’un model senzill en el qual el grau de reducció està en funció de la distància a les fonts de matèria primera. Els cinc jaciments de cova o abric coneguts contenen ocupacions de tipus logístic amb cadenes operatives de sílex representades de forma molt parcial i el rebuig de peces retocades transportades des de distàncies importants. En els jaciments costers es documenta el consum de mol·luscs de la zona eulitoral. Les restes humanes de la Sima de las Palomas proven la pervivència dels Neandertals en la regió fins almenys el 34.5 ka 14C BP.; Hay 36 yacimientos del Paleolítico Medio conocidos en la región de Murcia. Los yacimientos al aire libre son todos de superficie. Una concentración en el altiplano de Yecla indica que...

Influence of a biohermal belt on the lacustrine sedimentation of the Cañadón Asfalto Formation (Upper Jurassic, Chubut province, Southern Argentina)

Cabaleri, N.G.; Armella, C.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2005 ENG
Relevância na Pesquisa
16.86%
The Upper Jurassic Cañadón Asfalto Formation (Cañadón Asfalto Basin, Patagonia Argentina), consists mainly of carbonate deposits accumulated in hydrologically closed lakes, which were especially sensitive to rainfall changes. The lacustrine carbonate sedimentation also interplayed with volcanic episodes recorded by tuffs and lavas, as observed in different basin sectors. These lakes probably underwent warm, alternating humid-subarid and arid conditions that resulted in spreading and shrinkage cycles of the closed water bodies. In the Cerro Cóndor area, carbonates were deposited as part of a 500 m long and 39 m thick microbial biohermal body that extended over 5,5 km2, overlying a hard basalt substratum. This bioherm ridge acted as a physiographic barrier that controlled the sedimentation in the surrounding lacustrine zones, whose environments ranged from shallow and deep littoral to eulittoral (including microbial patch reefs) and palustrine. A hydrologically isolated portion of the lacustrine basin evolved into a pan lake where widespread carbonateevaporite sequences developed.