Hydrothermal Processes in the Solar System:A Review     

Franco PIRAJNO 　Martin J. Van KRANENDONK　Long XIAO 《地质科技情报》2008,27(1):1-12

最近美国航空与空间计划署(NASA)开展的卡西尼-惠更斯外空探测计划发现,在直径为500 km的卫星--土卫二上存在水冰和间隙泉的喷发活动.这一现象和在火星上工作的"机遇号"和"勇气号"漫游车所发现的液态水一起,证明了除地球以外的其他星球上过去和现在都存在水,其中的一些星体还有火山活动的证据,这意味着这些星球上可能存在过热液活动地质过程.讨论了火星、木卫二和土卫二可能存在的热液系统类型.这些热液系统类型是根据地球上的构造背景进行相似性研究后得出的,例如海底、火山和裂谷系统.将东非裂谷和贝加尔湖裂谷系统与火星Tharsis高原上巨大的水手大峡谷进行了对比,这些地区都是由地幔柱作用下构造-热液活动导致的地壳抬升、火山和裂谷作用.在火星上,地下冰或低温层会在火山活动和(或)小行星或彗星撞击作用下溶解而形成热液对流.  相似文献   

Aquifer chemistry of the Puga and Chumatang high temperature geothermal systems in India     

V.K. Saxena  Franco D'Amore 《Journal of Volcanology and Geothermal Research》1984,21(3-4)

Results of a chemical study of the fluids from drill holes and hot springs of Puga and Chumatang areas in the northwestern part of the Himalaya are presented and discussed in this paper. The thermal waters of Puga and Chumatang are of Na-HCO₃-Cl and Na-HCO₃ types, respectively. A comparison between these waters, their chemical classification and activity studies suggest a flow path within a quartzitic-schistose basement, containing quartz, K-feldspar and illite, and in clayey terrains containing montmorillonite and illite.The chemistry of thermal waters also indicate their association with magmatic activity. The chemical geothermometers indicate the possible existence of a geothermal reservoir at Puga with temperature ≈250°C. The Chumatang area has a comparatively cooler reservoir with a temperature of 150–180°C.  相似文献   

Evolution of Eolian arc volcanism (Southern Tyrrhenian Sea)     

Franco Barberi  Fabrizio Innocenti  Giorgio Ferrara  Jörg Keller  Letterio Villari 《Earth and Planetary Science Letters》1974,21(3):269-276

The Eolian arc is located at the boundary between the converging African and European plates. Its volcanism is characterized by a marked evolution in a restricted time (less than 1 my). A progressive transition is observed from typical calc-alkaline series toward shoshonitic rocks produced by past and present activity (Vulcano and Stromboli). By comparison with circum-Pacific island arcs, the evolution of Eolian volcanism can be related to a rapid deepening of the Benioff zone. The occurrence of shoshonitic rocks and the continental nature of the crust on both sides of the plate boundary suggest that the Eolian arc is in a senile stage of evolution. Petrology and Sr isotopic data indicate a probable mantle source for Eolian volcanism.  相似文献   

Thermal surveys on the Lake Garda by infrared equipments     

Dr. Michele Colacino  Prof. Maurizio Giorgi  Dr. Angelo Guerrini  Dr. Franco Vivona 《Meteorology and Atmospheric Physics》1976,25(2):159-170

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1980–1990: Ten years of geochemical investigation at Phlegrean Fields (Italy)     

Marino Martini  Luciano Giannini  Antonella Buccianti  Franco Prati  Paola Cellini Legittimo  Paolo Iozzelli  Bruno Capaccioni 《Journal of Volcanology and Geothermal Research》1991,48(1-2)

A systematic geochemical investigation on the thermal manifestations of the volcanic area of Phlegrean Fields started in 1980, with the aim of obtaining useful information about the changes possibly occurring at the same time of vertical ground movements, termed as “bradyseismic”, which frequently interested this area.The attention was initially given to the fumaroles and the boiling pools of Solfatara and Pisciarelli, then subsequently extended to thermal springs, dug wells, and crater lakes.Analytical data pertaining to a period preceding the last crisis of 1982–1984 were then available, as well as other data collected during the previous crisis of 1970; a comprehensive picture of the variations observed before, during and after the acceleration of vertical movement has been drawn.According to the results obtained, the intrusion of a magmatic body as the trigger of the observed ground deformation is considered unrealistic. The whole area appears now in a quiet stage, and no further perturbation is expected without previous significant tectonic activity; chemical precursors appear suitable for an early detection of changes occurring at depth, to forecast possible consequences to be expected in the surface environment.  相似文献   

El cretácico medio y superior de la parte meridional del Bloque Maya (Guatemala)     

F. Michaud  E. Fourcade  J. Azema  M.A. Carballo Hernandez  J.C.Franco Austin 《Journal of South American Earth Sciences》1992,5(3-4)

Study of the Cretaceous strata of the Altos Cuchumatanes (western Guatemala) and in Alta Verapáz (central Guatemala) has revealed a number of foraminifers never before reported from these areas. These data permit a similar nomenclature to be applied to both areas in regard to the division of the sequence into formations. Thus, we distinguish in both areas: a) the Cobán Formation, a shallow platform carbonate of early Aptian to early Senonian age; b) the Campur Formation, of Campanian age, composed of a lower carbonate member with rudists and large benthonic foraminifers, and an upper carbonate member with pelagic foraminifers; c) the Sepur Formation, of Maastrichtian age, with flysch-like sediments, including intercalated blocks of ophiolite complex obducted during the Maastrichtian. We conclude that in early Aptian time, a shallow carbonate platform developed along the southern margin of the Maya Block. The platform subsided and was drowned during the terminal Campanian. This subsidence led to the formation of a flysch-like basin that received turbiditic sedimentation from the carbonate platform to the north and fragments of serpentinite from the ophiolite complex to the south.  相似文献   

Climatology and interannual variability of storm-tracks in the Euro-Atlantic sector: a comparison between ERA-40 and NCEP/NCAR reanalyses   总被引：2，自引：0，他引：2  

Isabel Franco Trigo 《Climate Dynamics》2006,26(2-3):127-143

An objective methodology is applied to ERA-40 (European Centre for Medium-Range Weather Forecasts 40-year Reanalysis) and NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalyses, to build two storm-track databases for the Euro-Atlantic sector (85°W–70°E; 20°N–75°N), spanning the period December 1958–March 2000. The technique uses the full temporal (6-hourly) and spatial resolutions (1.125° and 2.5° regular grids, for ERA-40 and NCEP/NCAR, respectively) available. It is shown that the strong discrepancies in the number of storms in each dataset (higher for ERA-40) result from differences in the resolution of the fields subject to the storm detecting/tracking algorithm, and also from the characteristics of the integration models and assimilation schemes used for each reanalysis. An intercomparison of ERA-40 and NCEP/NCAR storm-tracks is performed for spatial distribution, and main characteristics, of the overall cyclone population and of a class of severe storms—explosive cyclones. Despite the discrepancies in storm numbers, both reanalyses agree on the main cyclone activity areas (formation, minimum central pressure, and lysis). The most pronounced differences occur where subsynoptic systems are frequent, as these are better resolved by ERA-40 data. The interannual variability of cyclone counts, analysed per intensity classes and for different regions of the domain, reveals reasonable agreement between the two datasets on the sign of trends (generally positive in northern latitudes, and negative in the Azores-Mediterranean band), but discrepancies regarding their strength in the most southern areas, where the mismatches between ERA-40 and NCEP/NCAR detected lows are greatest. Submitted to Climate Dynamics in December 2004  相似文献   

Evolution of the Mesozoic Granites in the Xiong＇ershan-Waifangshan Region, Western Henan Province, China, and Its Tectonic Implications   总被引：4，自引：0，他引：4       下载免费PDF全文

HAN Yigui  ZHANG Shihong  Franco PIRAJNO  ZHANG Yuanhou 《《地质学报》英文版》2007,81(2):253-265

Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong'ershan-Waifangshan region in western Henan Province: high-Ba-Sr I-type granite emplaced in the early stage (～160 Ma), I-type granite in the middle stage (～130 Ma) and anorogenic A-type granite in the late stage (～115 Ma).Geochemical characteristics of the high-Ba-Sr I-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New 40Ar/39Ar plateau ages of the early-stage Wuzhangshan granite (156.0±1.1 Ma, amphibole) and middle-stage Heyu granite (131.8±0.7 Ma, biotite) are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A-type granite, Taishanmiao pluton, was emplaced at ～115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between ～160 Ma and ～115 Ma. The genesis of the early- and middle-stage I-type granites could be linked to delamination of subducted lithosphere of the Qinling orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qinling -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial 87Sr/86Sr ratios,which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratons.  相似文献   

Delimitation of ground failure zones due to land subsidence using gravity data and finite element modeling in the Querétaro valley, México     

Jesús Pacheco  Jorge Arzate  Eduardo Rojas  Moises Arroyo  Vsevolod Yutsis  Gil Ochoa   《Engineering Geology》2006,84(3-4):143-160

Sedimentary basins of arid and semiarid zones are often subject to regimes of intense ground-water withdrawal as it is normally the only source of water for development of communities. An associated phenomenon is land subsidence, which can develop to ground failures, and consequently, damage to infrastructure. Aquifer deformation can be analyzed using a stress–strain or a flux–force approach depending on the aquifer material (compact or loose) and on whether the water withdrawal forms a predominant flow direction toward a cone of depression. Geometry of the aquifer system also plays an important role as uneven thickness induces differential compaction and hence, tensional and shear stresses on the ground mass. In this work we present a stress–strain approach to analyze subsidence for an unconfined aquifer of varying thickness; this is done in two steps, namely when the aquifer is in equilibrium, and when it is totally depleted. Using this scheme in a region where ground failure is evident, a portion of the aquifer system of the Querétaro valley is analyzed. The geometry of the hydrologic basement is first modeled using gravity measurements properly correlated with wells and field data. Then a stress analysis is implemented using the finite element method in order to identify probable zones of ground weakness, which are calibrated with known ground failures. The results indicate that both, tensional and shear stress are present, which induce ground failure in the form of surface faults.  相似文献   

Santite,a new mineral phase from Larderello,Tuscany     

Stefano Merlino  Franco Sartori 《Contributions to Mineralogy and Petrology》1970,27(2):159-165

A new borate mineral has been found in a sample from Larderello, mixed with larderellite and lesser amounts of sassolite. The mineral is never well crystallized, but it constantly appears as very small, clear and colourless grains; its refractive indices are: =1.422, =1.435, =1.480. Single-crystal X-ray photographs show that the mineral is orthorombic with cell dimensions: =11.10 Å, b=11.18 Å, c=9.08 Å. X-ray powder diffraction and partial chemical analyses carried out on the whole sample (it being impossible to separate a sufficient quantity of pure material) confirm the foregoing data, according to which the mineral may be considered as the natural equivalent of the synthetic compound KB₅O₈ · 4H₂O. It is likely that it originated from the reaction between potassium-bearing hot solutions and primary deposits of larderellite. It is named for the Tuscan naturalist Giorgio Santi.This new mineral has been approved by the Commission on New Minerals and New Mineral Names of the International Mineralogical Association.This research was supported by Consiglio Nazionale delle Ricerche, Roma.  相似文献