Essai d'organisation paléogéographique et structurale du PaléozoÏque des Andes Méridionales     

Prof. Jean -Claude Vicente 《International Journal of Earth Sciences》1975,64(1):343-394

Hercynian absolute ages obtained from many plutonites and metamorphites of the Sierras Pampeanas compel to consider this polymetamorphic domain rather as an intermediate hinterland and axis of divergent symmetry between the two elementary geosyncline ranges (Cuyanides and Bolivianides) of the south america hercynian orogen. Attempt of Cuyanides paleogeographic organization indice to define during the geosyncline period (Cambrian to Devonian):

the Pampean zone which consist of:

1. an internal sub-zone (eastern) or pampean s. st. with hinterland significance
2. a more external sub-zone (western) or transpampean or Umango sub-zone with intermediate features between eugeanticlinal ridge and eugeosynclinal furrow;
3. the Calingasta zone as a typical eugeosynclinal furrow with pelagic-terrigenous ordovician sedimentation and ophiolitic magmatism followed by early silurian than devonian Flyschs;
4. the Zonda zone as an external ridge with neritic cambro-ordovician facies and devonian flyschs.

The unwonted position of Zonda no metamorphic Facies surrounded by Calingasta and Umango metamorphic Facies, suggest its window situation and wide allochthonous structures for the internal zones. An eastward origin of the nappes is discussed in relation with pampean syntectonic metamorphism and plutonism. Essentially, structures are referred to the Acadian phase (= bretonic) but early paleo-hercynian phases are also emphasized to explain Flyschs sequences and some pampean plutonic cycles. Tardi- and Post-hercynian organization is briefly sketched with related molasses, neomolasses and magmatism. The remarquable geosyncline pattern of the Cuyanides is emphasizes in all stages of its evolution and under aspects however tectonic, magmatic and metamorphic. Finally, the fundamentally western polarity of the Cuyanides is replaced into the most general framework of Gondwanides organization.  相似文献   

Landscape evolution and geodynamic controls in the Gulf of Cadiz (Huelva coast, SW Spain) during the Late Quaternary     

Cari Zazo  Norbert Mercier  Pablo G. Silva  Cristino J. Dabrio  Jos Luis Goy  Elvira Roquero  Vicente Soler  Francisco Borja  Javier Lario  Dolores Polo  Luis de Luque 《Geomorphology》2005,68(3-4):269-290

The coastal evolution of the El Abalario area (Huelva, southern Spain) during the Late Pleistocene and Holocene is reinterpreted after a refinement of the available geochronology by means of optically stimulated luminescence (OSL) dating. New data come from the analysis of soft sediment deformation, palaeosols, geomorphological mapping, and published seismic surveys on the onshore and offshore Gulf of Cadiz.The present structure of El Abalario dome resulted from the complex interaction of littoral-catchment processes and sea-level changes upon an emergent coastal plain, conditioned by the upwarping of the underlying Pliocene–Pleistocene prograding deltaic sequence. Upwarping is probably related to escape of over-pressurized fluids, accompanied by dewatering, prior to (?) and during OIS (Oxygen Isotopic Stage) 5. Continued upwarping produced the large NW–SE gravitational fault of Torre del Loro (TLF) in the southwestern flank of the dome, roughly parallel to the present coastline during OIS 5–OIS 4. The resulting escarpment favoured the accumulation of aeolian sand dunes (units U1, U2, and U3) from OIS 5 to early OIS 1. Unit U1 (OIS 5) ends upwards in a supersurface with a thick weathering profile that suggests moist and temperate climatic conditions. Unit U2 accumulated mainly during OIS 4 and OIS 3 with prevailing W/E winds. The supersurface between U2 and U3 records a part of OIS 2, with relative low sea level. Sedimentation of unit U3 took place during the Last Deglaciation (radiocarbon and OSL ages) with prevailing W/SW winds, under a temperate moist climate, that became more arid towards the top (Holocene). A major supersurface with an iron crust-like layer (SsFe) developed during the Holocene Climatic Optimum (OIS 1) under wetter and more temperate conditions than before, fossilizing the TLF. The supersurface is covered by younger aeolian dunes (U4, U5, U6, and U7) transported by W–SW winds since the Late Neolithic–Chalcolithic cultural period (5.0 ky cal BP).  相似文献   

Detection of displacements on Tenerife Island, Canaries, using radar interferometry   总被引：1，自引：0，他引：1  

José Fernández  Rosana Romero  Daniel Carrasco  Kristy F. Tiampo  Gema Rodríguez-Velasco  Alfredo Aparicio  Vicente Araña  F. J. González-Matesanz 《Geophysical Journal International》2005,160(1):33-45

  相似文献   

MODELING SEDIMENT PROCESSES ON SMALL WATERSHEDS: A CONCEPTUAL FRAMEWORK Ⅱ. CONCENTRATED FLOW PROCESSES     

Vicente L. LOPES  Peter F. FFOLLIOTT Assistant Professor  School of Renewable Natural Resources  The University of Arizona. Tucson. Arizona. Professor  School of Renewable Natural Resources. The University of Arizona  Tucson. Arizona. 《国际泥沙研究》1993,(1)

L INTRODUCTIONThe purpose of this paper is to present a general modeling framework that can serveas a conceptual basis for developing sediment process models by concentrated flow systems on small watersheds. A survey of fundamental principles for developing sedimentprocess models is made with particular emphasis on the effects of space and time averaging on the governing equations. Starting from the most general one--dimensional,unsteady model of sediment processes, simpler model structur…  相似文献   

Remanent magnetization of andesitic and dacitic pumice from the 1985 eruption of Nevado del Ruiz (Colombia) reversed due to self-reversal     

Maja Haag  Friedrich Heller  Juan Carlos Carracedo  Vicente Soler 《Journal of Volcanology and Geothermal Research》1990,41(1-4)

The natural remanent magnetization of andesitic pumice emitted during the 1985 eruption of the Nevado del Ruiz volcano (Colombia) has a direction opposite to the present geomagnetic field. The self-reversing mechanism can be re-activated in the laboratory during cycles of heating and subsequent cooling in air and zero magnetic field. Laboratory-produced thermoremanent magnetization is dominated by the same self-reversal process in fields up to several mT. Microchemical, optical and Curie temperature analyses indicate that the ferromagnetic minerals are members of the magnetite-ulvöspinel and hematite-ilmenite series with average compositions of Fe_2.73Ti_0.27O₄ and Fe_1.38Ti_0.62O₃, respectively. In analogy with the magnetic behaviour of synthetically grown antiferromagnetic-ferromagnetic FeMn-FeNi films, the self-reversal can probably be interpreted in terms of an exchange field acting between a Ti-poor canted antiferromagnetic and a Ti-rich ferrimagnetic phase in the hemoilmenite grains.  相似文献   

Horizontal Anisotropy of the Principal Ground-Water Flow Zone in the Salinas Alluvial Fan, Puerto Rico   总被引：1，自引：0，他引：1  

Vicente Quiñones-Aponte 《Ground water》1989,27(4):491-500

  相似文献   

Impacts of future climate and land cover changes on landslide susceptibility: regional scale modelling in the Val d’Aran region (Pyrenees,Spain)     

Hürlimann  Marcel  Guo  Zizheng  Puig-Polo  Carol  Medina  Vicente 《Landslides》2022,19(1):99-118

It is widely accepted that future environmental changes will affect rainfall-induced shallow slides in high-mountain areas. In this study, the Val d’Aran region located in the Central Pyrenees was selected to analyze and quantify the impacts of land use and land cover (LULC) and climate changes on regional landslides susceptibility. We analyzed 26 climate models of the EURO-CORDEX database focussing on the future rainfall conditions. The IDRISI TerrSet software suite was used to create the future LULC maps. These two inputs were analyzed individually and in a combined way defining 20 different scenarios. All these scenarios were incorporated in a physically based stability model to compute landslides susceptibility maps. The results showed that both environmental conditions will considerably change in the future. The daily rainfall will increase between 14 and 26% assuming a return period of 100 years. This intensification of precipitation will produce an overall decrease of the stability condition in the study area. Regarding the LULC prediction, the forest area will significantly increase, while in particular grassland, but also shrubs decrease. As a consequence, the overall stability condition improves, because the root strength is higher in forest than in grassland and shrubs. When we analyzed the combined impacts, the results showed that the positive effect of LULC changes is larger than the negative influence of rainfall changes. Hence, when combining the two aspects in the future scenarios, the stability condition in the study area will improve.

  相似文献   

Environmental assessment of two artificial reef systems off southern Portugal (Faro and Olhão): A question of location     

M. Vicente  M. Falcão  M.N. Santos  M. Caetano  D. Serpa  C. Vale  C. Monteiro 《Continental Shelf Research》2008

This study investigates environmental assessment of artificial reef systems deployed at different areas in terms of nutrient cycling and seabed organic enrichment. Two identical artificial reef systems: Olhão Artificial Reef—OAR (37°00′55″N and 007°44′54″W) and Faro Artificial Reef—FAR (36°58′65″N and 008°00′91″W) were deployed in southern Portuguese coast, adjacent to a highly productive coastal lagoon (Ria Formosa) in 1990 and monitorized over two years (1992–1993). Water samples were collected within OAR and FAR systems, inside the lagoon (L) and in a non-reef area (NRA) to evaluate nutrient dynamics. Settled particles and sediment cores were also sampled within OAR and FAR to determine aluminium, calcium, silicon and chlorophyll a and organic and inorganic carbon, nitrogen and phosphorous. Results obtained showed that: (i) water column nutrients evidenced seasonal and spatial variability. The maximum nutrients concentration was recorded inside the lagoon and in OAR, mainly during warmer periods. Ammonium, nitrate and silicate in OAR were statistically higher (p<0.01, n=18) than in FAR and NRA; (ii) particulate organic carbon and nitrogen in FAR settled particles were significantly higher (p<0.005) than those collected at OAR; and (iii) organic carbon and nitrogen, calcium, aluminium and chlorophyll a in OAR upper sediment were higher than at FAR. The overall results suggest that OAR is a productive system, emphasizing its contribution to the trophic chain pull out, while FAR presented oceanic oligotrophic water.  相似文献   

Bioturbation and erosion rates along the soil-hillslope conveyor belt,part 2: Quantification using an analytical solution of the diffusion–advection equation     

Andrea Román-Sánchez  Ana Laguna  Tony Reimann  Juan Vicente Giráldez  Adolfo Peña  Tom Vanwalleghem 《地球表面变化过程与地形》2019,44(10):2066-2080

Particles on soil-mantled hillslopes are subject to downslope transport by erosion processes and vertical mixing by bioturbation. Both are key processes for understanding landscape evolution and soil formation, and affect the functioning of the critical zone. We show here how the depth–age information, derived from feldspar-based single grain post-infrared infrared stimulated luminescence (pIRIR), can be used to simultaneously quantify erosion and bioturbation processes along a hillslope. In this study, we propose, for the first time, an analytical solution for the diffusion–advection equation to calculate the diffusivity constant and erosion–deposition rates. We have fitted this model to age–depth data derived from 15 soil samples from four soil profiles along a catena located under natural grassland in the Santa Clotilde Critical Zone Observatory, in the south of Spain. A global sensitivity analysis was used to assess the relative importance of each model parameter in the output. Finally, the posterior probability density functions were calculated to evaluate the uncertainty in the model parameter estimates. The results show that the diffusivity constant at the surface varies from 11.4 to 81.9 mm² a^-1 for the hilltop and hill-base profile, respectively, and between 7.4 and 64.8 mm² a^-1 at 50 cm depth. The uncertainty in the estimation of the erosion–deposition rates was found to be too high to make a reliable estimate, probably because erosion–deposition processes are much slower than bioturbation processes in this environment. This is confirmed by a global sensitivity analysis that shows how the most important parameters controlling the age–depth structure in this environment are the diffusivity constant and regolith depth. Finally, we have found a good agreement between the soil reworking rates proposed by earlier studies, considering only particle age and depth, and the estimated diffusivity constants. The soil reworking rates are effective rates, corrected for the proportion of particles actually participating in the process. © 2019 John Wiley & Sons, Ltd.  相似文献   

Assessment of the oil source-rock potential of the Pedregoso Formation (Early Miocene) in the Falcón Basin of northwestern Venezuela     

Jean Carlos Montero-Serrano  Manuel Martínez  Armelle Riboulleau  Nicolas Tribovillard  Gonzalo Márquez  José Vicente Gutiérrez-Martín 《Marine and Petroleum Geology》2010

The early Miocene Pedregoso Formation is one of the numerous formations rich in organic matter within the stratigraphic record of the Urumaco Trough, in the central area of the Falcón Basin. Due to its lithological characteristics and stratigraphic position, this formation is of great interest regarding the basin's petroliferous systems. The evaluation of various inorganic and organic geochemical parameters indicates that the organic matter is primarily of marine origin, deposited in a marine carbonate environment typical of reefal systems, under oxic-to-dysoxic conditions. The low variability in the TOC concentrations and in the distributions of the biomarkers extracted from the samples suggests that the paleoenvironmental conditions and the organic-matter supply remained approximately constant throughout the sedimentation of this unit. The Pedregoso type-II organic matter (marine origin) and initial organic richness value (∼1.8%) suggest that this unit has probably generated hydrocarbons within the Urumaco Trough. However, present-day thermal maturity parameters reveal that the Pedregoso organic matter is overmature (dry gas window), indicating that this unit is only capable to generate gas. In addition, the geothermal gradient, maturity parameters, and the maximum paleotemperature estimated in this study suggest that the Pedregoso Formation reached a maximum burial depth the ∼6.5 km, consistent with the value obtained from data of stratigraphic thickness in the Urumaco Trough. This implies that the thermal anomaly that affected the basin during the Late Eocene–Early Miocene did not reach the central part of the basin, and therefore, the organic matter maturation in this unit is due to the sedimentary burial.  相似文献