Climate and landscape during Heinrich Event 3 in south‐western Europe: the small‐vertebrate association from Galls Carboners cave (Mont‐ral,Tarragona, north‐eastern Iberia)          下载免费PDF全文

JUAN MANUEL LÓPEZ‐GARCÍA  HUGUES‐ALEXANDRE BLAIN  MARIA BENNÀSAR  JOSEP ANTONI ALCOVER  SANDRA BAÑULS‐CARDONA  MÓNICA FERNÁNDEZ‐GARCÍA  MARTA FONTANALS  PATRICIA MARTÍN  JUAN IGNACIO MORALES  LAURA MUÑOZ  MIREIA PEDRO  JOSEP MARÍA VERGÉS 《第四纪科学杂志》2014,29(2):130-140

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Reproductive traits of tropical deep-water pandalid shrimps (Heterocarpus ensifer) from the SW Gulf of Mexico     

Patricia Briones-Fourzán  Cecilia Barradas-Ortíz  Fernando Negrete-Soto  Enrique Lozano-Álvarez 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(8):978-987

Heterocarpus ensifer is a tropical deep-water pandalid shrimp whose reproductive features are poorly known. We examined reproductive traits of a population of H. ensifer inhabiting the continental slope (311–715 m in depth) off the Yucatan Peninsula, Mexico (SW Gulf of Mexico). Size range of the total sample (n=816) was 10.4–38.9 mm carapace length. Females grow larger than males, but both sexes mature at 57% of their maximum theoretical size and at ～30% of their total lifespan. Among adult females, the proportion of ovigerous females was high in all seasons, indicating year-round reproduction. Most females carrying embryos in advanced stages of development had ovaries in advanced stages of maturation, indicating production of successive spawns. In the autumn, however, the proportion of ovigerous females and the condition index of these females were lower compared to other seasons. This pattern potentially reflects a reduction in food resources following the summer minimum in particulate organic carbon flux to the deep benthos, as reported in previous studies. Spawns consisting of large numbers (16024±5644, mean±SD) of small eggs (0.045±0.009 mm³) are consistent with extended planktotrophic larval development, an uncommon feature in deep-water carideans. Egg number increased as a power function of female size but with substantial variability, and egg size varied widely within and between females. There was no apparent trade-off between egg number and egg size and neither of these two variables was influenced by female condition. These results indicate iteroparity and a high and variable reproductive effort, reflecting a reproductive strategy developed to compensate for high larval mortality. The present study provides a baseline to compare reproductive traits between Atlantic populations of this tropical deep-water pandalid.  相似文献   

Oriented growth of garnet by topotactic reactions and epitaxy in high‐pressure,mafic garnet granulite formed by dehydration melting of metastable hornblende‐gabbronorite (Jijal Complex,Kohistan Complex,north Pakistan)     

J. A. PADRÓN‐NAVARTA  C. J. GARRIDO  A. SÁNCHEZ‐NAVAS  A. TOMMASI  V. LÓPEZ SÁNCHEZ‐VIZCAÍNO  M. T. GÓMEZ‐PUGNAIRE  S. S. HUSSAIN 《Journal of Metamorphic Geology》2008,26(8):855-870

Garnet growth in high‐pressure, mafic garnet granulites formed by dehydration melting of hornblende‐gabbronorite protoliths in the Jijal complex (Kohistan palaeo‐island arc complex, north Pakistan) was investigated through a microstructural EBSD‐SEM and HRTEM study. Composite samples preserve a sharp transition in which the low‐pressure precursor is replaced by garnet through a millimetre‐sized reaction front. A magmatic foliation in the gabbronorite is defined by mafic‐rich layering, with an associated magmatic lineation defined by the shape‐preferred orientation (SPO) of mafic clusters composed of orthopyroxene (Opx), clinopyroxene (Cpx), amphibole (Amp) and oxides. The shape of the reaction front is convoluted and oblique to the magmatic layering. Opx, Amp and, to a lesser extent, Cpx show a strong lattice‐preferred orientation (LPO) characterized by an alignment of [001] axes parallel to the magmatic lineation in the precursor hornblende‐gabbronorite. Product garnet (Grt) also displays a strong LPO. Two of the four 〈111〉 axes are within the magmatic foliation plane and the density maximum is subparallel to the precursor magmatic lineation. The crystallographic relationship 〈111〉_Grt // [001]_Opx,Cpx,Amp deduced from the LPO was confirmed by TEM observations. The sharp and discontinuous modal and compositional variations observed at the reaction front attest to the kinetic inhibition of prograde solid‐state reactions predicted by equilibrium‐phase diagrams. The P–T field for the equilibration of Jijal garnet granulites shows that the reaction affinities are 5–10 kJ mol.^?1 for the Grt‐in reaction and 0–5 kJ mol.^?1 for the Opx‐out reaction. Petrographic and textural observations indicate that garnet first nucleated on amphibole at the rims of mafic clusters; this topotactic replacement resulted in a strong LPO of garnet. Once the amphibole was consumed in the reaction, the parallelism of [001] axes of the mafic‐phase reactants favoured the growth of garnet crystals with similar orientations over a pyroxene substrate. These aggregates eventually sintered into single‐crystal garnet. In the absence of deformation, the orientation of mafic precursor phases conditioned the nucleation site and the crystallographic orientation of garnet because of topotaxial transformation reactions and homoepitaxial growth of garnet during the formation of high‐pressure, mafic garnet‐granulite after low‐pressure mafic protoliths.  相似文献   

Impact area determination of pyroclastic deposits in Lascar volcano, eruptive process in the year 1993     

Luis Fernández  Gabriel Álvarez  Renato Salinas 《Natural Hazards》2012,60(2):747-760

By means of multi-temporal analysis of satellite images and statistical algorithms, the amount of pyroclastic material deposited on Lascar volcano walls after the gravitational collapse of the eruptive column caused by the eruption that occurred on April the 19th and the 20th in 1993 was determined and quantified. For this analysis, scenes corresponding to Landsat 4 TM in 1989 and Landsat 7 ETM+ in 2001 were used. By careful selection methods such as combination of bands, unsupervised classification, and the Karhunen–Loève transform, detailed analysis of zones of change that correspond to pyroclastic deposits were made. This analysis was complemented with in situ data in order to correct and calibrate the satellite images to identify zones of 1993s eruption pyroclastic deposits. Using Kittler’s and other thresholding algorithms, a search was performed for a proper threshold to binarize the images to determine the surface area covered by the eruptive process. Matlab™ software was used both for general programming and for digital image processing.  相似文献   

Fluoride sorption and desorption on soils located in the surroundings of an aluminium smelter in Galicia (NW Spain)     

C. Gago  A. Romar  M. L. Fernández-Marcos  E. Álvarez 《Environmental Earth Sciences》2014,72(10):4105-4114

Aluminium smelters are major sources of F emission to the environment. We studied, in laboratory experiments, the sorption and desorption of fluoride on organic and mineral horizons of soils located within 2 km from one of these factories, situated in the northern coast of Galicia (NW Spain). The soils, developed from granite, are acid (pH H₂O 3.9–5.5), rich in organic matter (4–16 % C in the A horizon) and most A horizons have high Al saturation in the exchange complex. All samples showed a notable F sorption, between 1,066 and 1,589 mg kg^?1, after adding 200 mg F L^?1, which accounts for 53–80 % of F added. The sorption was slightly higher in the A horizons than in the respective organic horizons (differences of up to 194 mg kg^?1). The fluoride sorption upon addition of 200 mg F L^?1 correlated significantly (p < 0.05) with soil pH in water (r = ?0.77), iron extracted by acid ammonium oxalate (r = 0.68), aluminium plus iron extracted by acid ammonium oxalate (r = 0.63), exchange aluminium (r = 0.52) and clay percentage in soil (r = 0.76). The F sorption fitted to both Langmuir and Freundlich models. Desorbed F accounted for only 12–22 % of sorbed fluoride and correlated (p < 0.05) negatively with non-crystalline (extracted by acid ammonium oxalate) Fe (r = ?0.51) and clay content (r = ?0.74) and positively with organic matter (r = 0.69) and with the effective cation exchange capacity of the soil (r = 0.50).  相似文献   

Kimmeridgian protoglobigerinids (Foraminifera) from Crussol (SE France)     

Ágnes Görög  Roland Wernli 《Swiss Journal of Geoscience》2010,103(1):83-100

A detailed investigation of the protoglobigerinids from the Kimmeridgian section of the Montagne de Crussol, SE France is presented. This monotonous succession of predominantly carbonate beds represents peri-platform hemipelagic deposits, well dated by ammonites. Three species were determined in thin sections and in isolated forms after extraction by acetolysis. Favusella? parva (Kuznetsova) is the most common species occurring in almost the entire succession from the Orthosphinctes to the Beckeri zones. Favusella hoterivica (Subbotina) has been retrieved less frequently from the Platynota to the Beckeri zones, and it is its oldest occurrence. The rare Globuligerina bathoniana (Pazdrowa) occurs only in the Late Kimmeridgian. Based on our study and the review of the literature a palaeogeographical map was plotted, showing that most of the protoglobigerinid occurrences are in deep water facies of the northern margin and central part of the Tethys. These records demonstrate the presence of Globuligerina bathoniana, G. oxfordiana (Grigelis), Favusella hoterivica, F.? parva and Compactogerina stellapolaris (Grigelis) in the Kimmeridgian.  相似文献   

The 2dF QSO Redshift Survey – XIV. Structure and evolution from the two-point correlation function     

Scott M. Croom  B. J. Boyle  T. Shanks  R. J. Smith  L. Miller  P. J. Outram  N. S. Loaring  F. Hoyle  J. da Ângela 《Monthly notices of the Royal Astronomical Society》2005,356(2):415-438

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Photometric redshifts: spectroscopy AT Δλ / λ ≈ 0.1     

A. FernÁndez-Soto 《Astrophysics and Space Science》2001,276(2-4):965-972

I discuss the advantages that photometric redshift techniques offer over traditional (spectroscopic) redshift determination methods. It is shown that the former represents the only means we have of studying the faint distant galaxy population as a whole, and that, in its range of applicability, it delivers excellent results that can add to our knowledge of galaxy formation and evolution processes. Along this line, I also present some of the results extracted from a photometric redshift catalogue of galaxies in the Hubble Deep Field (HDF), including measurements of the star formation density in the high-redshift Universe, morphological evolution of galaxies, and detection of some of the most distant galaxies ever observed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Study of magnetic contrasts applied to hydrocarbon exploration in the Maturín Sub-Basin (eastern Venezuela)     

Oswaldo Guzmán  Vincenzo Costanzo-Álvarez  Milagrosa Aldana  Marisel Díaz 《Studia Geophysica et Geodaetica》2011,55(2):359-376

We have studied near-surface magnetic contrasts in nine oil wells from an oil prospective area in eastern Venezuela (compressive deformation front of the northeastern Maturín Sub-Basin). Samples are drill cuttings taken at intervals of about 15 m within approximately the first 1200 m of most of these wells. Rock magnetic experiments, electron paramagnetic resonance (EPR), extractable organic matter (EOM), X-ray diffraction and scanning electron microscopy (SEM) are used to discriminate between two anomalies in magnetic susceptibility (MS), related to either a reducing environment caused by the underlying reservoir (Type A), or to primary lithological contrasts (Type B). Contour maps of MS, S-ratio and organic-matter-free radical concentrations (OMFRC), for the A-like depth levels, show a major central zone of anomalous high values. This area is probably associated with either maximum accumulation of hydrocarbons in the reservoir or with their southerly migration from the northern petroleum source towards the deformation front. We argue that such a result could be used, for future exploration and production ventures in the region, as a preliminary characterization of the reservoir. We also show in a Day plot, that saturation remanence — saturation magnetization ratio (M_rs/M_s) and coercivity of remanence — coercive force ratio (H_cr/H_c) stand as additional criteria to discriminate between these two types of magnetic contrasts. In fact, for the area of study, hysteresis ratios show three distinct trends corresponding to samples from A-like, B-like and non-anomalous depth levels.  相似文献   

Selective blackening of bioclasts via mixing‐zone aragonite neomorphism in Late Triassic limestone,Zlatibor Mountains,Serbia     

KINGA HIPS  JÁNOS HAAS  MÁRIA VIDÓ  ZSUZSANNA BARNA  DIVNA JOVANOVIĆ  MILAN N. SUDAR  ZOLTÁN SIKLÓSY 《Sedimentology》2011,58(4):854-877

A peculiar facies of the Norian–Rhaetian Dachstein‐type platform carbonates, which contains large amounts of blackened bioclasts and dissolutional cavities filled by cements and internal sediments, occurs in the Zlatibor Mountains, Serbia. Microfacies investigations revealed that the blackened bioclasts are predominantly Solenoporaceae, with a finely crystalline, originally aragonite skeleton of fine cellular structure. Blackening of other bioclasts also occurs subordinately. Solenoporacean‐dominated reefs, developed behind the platform margin patch‐reef tract, were the main source of sand‐sized detritus. The blackened and other non‐blackened bioclasts are incorporated in automicrite cement. Radiaxial fibrous calcite cements in the dissolutional cavities are also black, dark grey or white. Reworked black pebbles were reported from many occurrences of peritidal deposits; in those cases, the blackening took place under pedogenic, meteoric diagenetic conditions. In contrast, in the inner platform deposits of the Ilid?a Limestone, the blackening of bioclasts occurred in a marine–meteoric mixing‐zone, as indicated by petrographic features and geochemical data of the skeleton‐replacing calcite crystals. Attributes of mixing‐zone pore waters were controlled by mixing corrosion, different solubility of carbonate minerals and microbial decomposition of organic matter. In the moderate‐energy inner platform environment, large amounts of microbial organic tissue were accumulated and subsequently decomposed, triggering selective blackening in the course of early, shallow burial diagenesis. The δ¹⁸O and δ¹³C values of the mixing‐zone precipitates and replacive calcite do not produce a linear mixing trend. Variation mainly resulted from microbial decomposition of organic matter that occurred under mixing‐zone conditions. The paragenetic sequence implies cyclic diagenetic conditions that were determined by marine, meteoric and mixing‐zone pore fluids. The diagenetic cycles were controlled by sea‐level fluctuations of moderate amplitude under a semi‐arid to semi‐humid climate.  相似文献