Phytoplankton productivity in relation to light intensity: A simple equation     

D. H. Peterson  M. J. Perry  K. E. Bencala  M. C. Talbot 《Estuarine, Coastal and Shelf Science》1987,24(6)

A simple exponential equation is used to describe photosynthetic rate as a function of light intensity for a variety of unicellular algae and higher plants where photosynthesis is proportional to (1-e^−β1). The parameter β ( ) is derived by a simultaneous curve-fitting method, where I is incident quantum-flux density. The exponential equation is tested against a wide range of data and is found to adequately describe P vs. I curves. The errors associated with photosynthetic parameters are calculated. A simplified statistical model (Poisson) of photon capture provides a biophysical basis for the equation and for its ability to fit a range of light intensities. The exponential equation provides a non-subjective simultaneous curve fitting estimate for photosynthetic efficiency (a) which is less ambiguous than subjective methods: subjective methods assume that a linear region of the P vs. I curve is readily identifiable. Photosynthetic parameters β and a are used widely in aquatic studies to define photosynthesis at low quantum flux. These parameters are particularly important in estuarine environments where high suspended-material concentrations and high diffuse-light extinction coefficients are commonly encountered.  相似文献   

The adsorption of rhodamine on to suspended sediments     

Talbot  J. W.; Boon  Myrtle J. 《ICES Journal of Marine Science》1975,36(2):128-132

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The Adsorption of Rhodamine-B on to Materials Carried in Suspension by Inshore Waters     

Talbot  J. W.; Henry  J. L. 《ICES Journal of Marine Science》1968,32(1):7-15

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A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran)   总被引：3，自引：0，他引：3  

A. Ghasemi  C.J. Talbot 《Journal of Asian Earth Sciences》2006,26(6):683-693

Recent geochemical studies of volcanic rocks forming part of the ophiolites within the Zagros and Naien-Baft orogen indicate that most of them were developed as supra-subduction ophiolites in intra-oceanic island arc environments. Intra-oceanic island arcs and ophiolites now forming the Naien-Baft zone were emplaced southwestward onto the northeastern margin of the South Sanandaj–Sirjan Zone, while those now in the High Zagros were emplaced southwestward onto the northern margin of Arabia. Thereafter, subduction continued on opposite sides of the remnant oceans. The floor of Neo-Tethys Ocean was subducted at a low angle beneath the entire Sanandaj–Sirjan Zone, and the floor of the Naien-Baft Ocean was subducted beneath the Central Iranian Micro-continent. The Naien-Baft Ocean extended into North-West Iran only temporarily. This failed ocean arm (between the Urumieh-Dokhtar Magmatic Assemblage and the main Zagros Thrust) was filled by thick Upper Triassic–Upper Jurassic sediments. The Naien-Baft Ocean finally closed in the Paleocene and Neo-Tethys closed in the Early to Middle Eocene. After Arabia was sutured to Iran, the Urumieh-Dokhtar Magmatic Assemblage recorded slab break-off in the Middle Eocene.  相似文献   

Three-dimensional forward and backward modelling of diapirism: numerical approach and its applicability to the evolution of salt structures in the Pricaspian basin     

Alik Ismail-Zadeh  Igor Tsepelev  Chistopher Talbot  Alexander Korotkii   《Tectonophysics》2004,387(1-4):81-103

Numerical studies of ductile deformations induced by salt movements have, until now, been restricted to two-dimensional (2D) modelling of diapirism. This paper suggests a numerical approach to model the evolution of three-dimensional (3D) salt structures toward increasing maturity. This approach is also used here to restore the evolution of salt structures through successive earlier stages. The numerical methodology is applied to study several model examples. We analyse a model of salt diapirs that develop from an initial random perturbation of the interface between salt and its overburden and restore the evolved salt diapirs to their initial stages. We show that the average restoration errors are less than 1%. An evolutionary model of a 2D salt wall loaded by a 2D pile of sediments predicts a decomposition of the salt wall into 3D diapiric structures when the overburden of salt is supplied by 3D synkinematic wedge of sediments. We model salt extrusion feeding a gravity current over the depositional surface and estimate an average rate of extrusion and horizontal velocity of salt spreading. Faulting of the overburden to salt overhangs initiates new secondary diapirs, and we analyse the growth of these secondary diapirs. We also study how lateral flow effects the evolution of salt diapirs. The shape of a salt diapir can be very different if the rate of horizontal flow is much greater than the initial rate of diapiric growth solely due to gravity. We discuss the applicability of the results of the models to the evolution of Late Permian salt structures in the Pricaspian basin (Russia and Kazakhstan). These structures are distinguishable into a variety of styles representing different stages of growth: salt pillows, diapirs, giant salt massifs, 2D diapiric walls and 3D stocks complicated by large overhangs. The different sizes, shapes and maturities of salt structures in different parts of the Pricaspian basin reflect areal differences in salt thickness and loading history. Our results suggest that the numerical methodology can be employed to analyse the evolution of all salt structures that have upbuilt through younger ductile overburdens.  相似文献   

“Evidence for Triassic salt domes in the Tunisian Atlas from gravity and geological data” by C. Jallouli et al., Tectonophysics 396 (2005) 209–225     

Christopher J. Talbot 《Tectonophysics》2005,406(3-4):249-254

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The preservation of scleractinian corals by calcite in the corallian beds (Oxfordian) of southern England     

M. R. Talbot 《International Journal of Earth Sciences》1972,61(2):731-742

Corals in the Oxfordian barrier-reef complex of southern England show great variations in the style and quality of preservation. Preservation was influenced by differences in the structure and chemical composition of the skeleton and by diagenetic effects such as the production of fibrous aragonite overgrowths and micrite cement. In all cases, however, the aragonite dissolved. Calcite usually precipitated in the resultant voids.

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Zusammenfassung Die Korallen des Oxford-Barriere-Riffkomplexes in Südengland unterscheiden sich wesentlich in Wuchsform und Erhaltungszustand. Der Erhaltungszustand wird durch die primären Strukturunterschiede und die chemische Zusammensetzung des Skelettes sowie durch frühdiagenetische Veränderung — wie Aragonitnadel- oder Mikrit-Zemenet — bestimmt. Der primäre Aragonit des Skelettes hat sich in jedem Fall aufgelöst, und in den dabei entstandenen Hohlräumen wird Kalzit gefällt.

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Résumé Les coraux du complexe de récif en barrière Oxfordienne d'Angleterre du sud montrent les grandes variations dans le style et la qualité de l'état de conservation. Cet état a été influencé par les différences de construction et de composition chimique du squelette et par les effets du premier stade de la diagenèse tels que la production des surcroissances de l'aragonite fibreuse et le ciment micritique. Cependant, dans tous les cas l'originale aragonite s'est dissoute, et la calcite a été précipitée dans les espaces vides résultants.

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Microbial ecology of the stratified water column of the Black Sea as revealed by a comprehensive biomarker study   总被引：2，自引：0，他引：2  

Stuart G. Wakeham  Rudi Amann  Katherine H. Freeman  Ellen C. Hopmans  Bo Barker Jrgensen  Isabell F. Putnam  Stefan Schouten  Jaap S. Sinninghe Damst  Helen M. Talbot  Dagmar Woebken 《Organic Geochemistry》2007,38(12):2070-2097

The stratified water column of the Black Sea is partitioned into oxic, suboxic, and euxinic zones, each characterized by different biogeochemical processes and by distinct microbial communities. In 2003, we collected particulate matter by large volume in situ filtration at the highest resolution to date for lipid biomarker analysis and bacterioplankton for enumeration of major prokaryotic groups. Abundances of several prokaryotic groups were estimated using CARD-FISH probes specific for Bacteria, Archaea (Crenarchaeota and Euryarchaeota), epsilonproteobacteria (mainly sulfide oxidizers) and sulfate reducing bacteria. We also measured a wide range of bacterial and archaeal lipid biomarkers. Depth distributions of diagnostic biomarkers are matched with zonation of microbial processes, including aerobic bacterial oxidation of methane, oxidation of ammonium by bacteria and archaea, metal reduction, and sulfide oxidation at the chemocline, and bacterial sulfate reduction and anaerobic oxidation of methane by archaea in the anoxic zone. Cell densities for archaea and sulfate reducing bacteria are estimated based on water column biomarker concentrations and compared with CARD-FISH results.  相似文献   

Fold trains in a glacier of salt in southern Iran     

C.J. Talbot 《Journal of Structural Geology》1979,1(1):5-18

A substantial glacier of rock salt flows downslope north eastwards from the salt dome at Kuh-e-Namak (Dashti), and this work describes and attempts to rationalise the deformation structures within it. The crystalline halite in both the salt dome and the glacier consists of layers of different colours, grain size and relatively insoluble mineral content. The colour bands develop folds which, together with tectonic slides, thin and multiply the colour bands in successive zones down the length of the glacier.The folds occur as trains in which the individual components increase in maturity as they move downstream. The folds characteristically mature over short distances and become isoclinal between successive fold generation zones so that refolding is rarely obvious. All the folds seen can be attributed to changes in the boundary conditions of the glacier—either of a general or local nature. Some folds can be explained in terms of either a former increase in volume or the current wasting of the salt sheet—but most obviously relate to irregularities in the bedrock channel negotiated by the salt during its downslope flow. Expressed in these terms most folds form where the salt glacier decelerates, and become inconspicuous where it accelerates.The relative volume of the glacier slowed by each bedrock irregularity impeding its flow decreases systematically down its length. This is thought to be due to a general decrease in competence of the rock salt down the length of the glacier as a result of a decrease in the grain size of the halite and the relative increase in the proportion of insoluble minerals due to the loss of halite by solution. The downstream decrease in grain size is similar to the process of mylonitisation in other rocks, and tends to be concentrated in particular parts of each fold generation zone.A foliation is defined to differing degrees in various parts of the glacier by shape fabrics in one or more of the glacier's three components: porphyroclastic remnants of the coarse grained transparent halite characteristic of the salt dome, a fine grained halite groundmass, and the entrained insoluble minerals. The clear halite porphyroclasts appear least susceptible to strain but their presence controls whether or not the colour bands fold near irregularities in the bedrock channel.Similarities between the structures in the salt glacier and those developed in various other rocks are obvious.  相似文献   

Crenulation cleavage in the Hunsrückschiefer of the middle moselle region     

J. L. Talbot 《International Journal of Earth Sciences》1965,54(2):1026-1043

A crenulation cleavage superimposed on an earlier (slaty-fracture) cleavage is widespread in the Hunsrückschiefer south of the Moselle. This second cleavage lies at about 30° to the earlier cleavage even though the first cleavage shows a wide range of attitudes. Field and thin section studies indicate that the different appearance of the two cleavages depends on the pre-existing fabric and does not necessarily reflect diverse modes of origin.

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Zusammenfassung Im Hunsrück-Schiefer der südlichen Mosel-Mulde kommen zwei Arten von Schiefergefügen vor, die erste Schieferung oder Transversalschieferung und die zweite Schieferung oder Schubklüftung. Obwohl die erste Schieferung sehr veränderliche Fälle zeigt, liegt die zweite Schieferung immer etwa 30° von der ersten. Gelände- und Dünnschliffuntersuchungen deuten an, daß die augenscheinlichen Unterschiede zwischen den beiden Schieferungen eine Folge der Unterschiede des bestehenden Gefüges ist und nicht ein Resultat verschiedenen Ursprungs.

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Résumé Un microplissement se surimpose fréquemment à une schistosité plus ancienne dans le Hunsruckschiefer au sud de la Moselle.Ce microplissement conserve un angle de 30° par rapport à la schistosité, même lorsque celle-ci est très variable.Les travaux de terrain et les études sur lames minces montrent que les différences entre ces deux natures de clivage résultent de la structure d'origine et ne reflètent pas nécessairement les influences génétiques subies par la roche.

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