The andes of northwestern Argentina     

Dr. Juan Carlos M. Turner 《International Journal of Earth Sciences》1970,59(3):1028-1063

This paper is a synthesis of the geological information available at present. The area studied comprises the Andes of Salta and Jujuy and the Puna; these geographical regions approximately correspond to the geological provinces of the Cordillera Oriental and the Puna.The geologic column comprises Precambrian metamorphics and intrusives, marine Lower Paleozoic, continental Upper Paleozoic, Cretaceous, and Upper Cenozoic. In the Puna, the Upper Cenozoic is characterized by extensive volcanism with dacitic and andesitic flows and tuffs, and with final basalt flows.Numerous unconformities have been recognized. In the Cordillera Oriental and in the basin range of the Puna, folds and faults occur, the latter are mainly high-angle reverse faults, dipping west in the eastern and east in the western portion of the area studied. The Cordillera Oriental, which is a shear zone at the eastern border of the Puna, is slightly younger than the Puna.

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Zusammenfassung Die vorliegende Arbeit stellt eine Zusammenfassung der augenblicklich vorhandenen geologischen Kenntnisse dar.Die Anden von Salta und Jujuy einerseits und die Puna andererseits sind die beiden geographischen Gebiete, mit denen sich die Untersuchungen befassen und die ungefähr mit den geologischen Provinzen der Ostkordillere und der Puna zusammenfallen.Die geologische Folge umfaßt metamorphe Gesteine und Intrusiva des Präkambriums, marine Sedimente des Alt-Paläozoikums, kontinentale Sedimente des Jung-Paläozoikums, der Kreide und des jüngeren Känozoikums, das letztere mit einem ausgedehnten vulkanischen Zyklus, aus dem dacitische und andesitische Laven und Tuffe hervorgingen, die mit basaltischen Ergüssen abschlossen.Es wurden zahlreiche Diskordanzen angetroffen. In der Ost-Kordillere und in den Gebirgsblöcken (basin range) der Puna besteht die Struktur aus Faltung und Klüftung. Die Mehrzahl der Klüfte sind inverse Störungen mit großer Sprunghöhe, die im östlichen Gebiet nach Westen und im westlichen nach Osten einfallen. Die Ost-Kordillere, die Scherzone am östlichen Rand der Puna, ist etwas jünger als letztere.

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Resumen El trabajo es una síntesis de la información geológica disponible en la actualidad. Los Andes de Salta y Jujuy y la Puna son las dos regiones geográficas que abarca la comarca en estudio, que corresponden aproximadamente a las provincias geológicas Cordillera Oriental y Puna.La columna geológica comprende metamorfitas y rocas intrusivas del Precámbrico, sedimentos marinos del Paleozoico inferior, sedimentos continentales del Paleozoico superior, Cretácico y Cenozoico superior. En esté último hubo un amplio ciclo volcánico, que originó coladas y tobas dacíticas y andesíticas y, finalmente, coladas basálticas.Se han reconocido varias discordancias. La estructura es de plegamiento y fallamiento en la Cordillera Oriental y de montañas de bloque en la Puna. En su mayoría, las fracturas son fallas inversas de alto-ángulo, que inclinan hacia el oeste en el tramo oriental y hacia el este en el tramo occidental. La Cordillera Oriental, zona de cizalla en el borde oriental de la Puna, es algo más joven que ésta.

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Résumé La présente contribution est une synthèse de toute l'information géologique disponible actuellement. Les régions étudíées sont, au point de vue géographique, les Andes de Salta et Jujuy et la Puna qui correspondent approximativement aux provinces géologiques de la Cordillera Oriental et de la Puna.Le Précambrien est représenté par des roches métamorphiques et intrusives. Au Paléozoïque inferieur correspondent des sédiments marins, tandis que des sédiments continentaux sont datés du Paléozoïque supérieur, du Crétacé et du Cénozoïque supérieur. Un important cycle volcanique est représenté par coulées et tufs dacitiques et andésitiques, couronnées par des coulées basaltiques.Plusieurs discordances ont été reconnues. La Cordillera Oriental et les montagne de la Puna présentent une structure de plissement et fracturation. La plupart des fractures sont inverses à fort pendange vers l'ouest du côté oriental et vers l'est du côté occidental. La Cordillera Oriental, la zone de cisaillement au bord oriental de la Puna, est plus jeune que celle-ci.

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Publication authorized by the Director, Dirección Nacional de Geología y Minería.  相似文献   

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Zheng GJ  Martin M  Richardson BJ  Yu H  Liu Y  Zhou C  Li J  Hu G  Lam MH  Lam PK 《Marine pollution bulletin》2004,49(5-6):520-524

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In contrast to local perceptions, the impact on the local Galápagos artisanal fishery of the 16 January 2001 grounding of the Jessica and subsequent oil spill was relatively minor. No significant changes in fishing effort, total fishing catches or catch-per-unit effort were detected after the spill based on analyses of fisheries monitoring data. Nevertheless, large boats tended to move away from sites near the path of the spill following the grounding in 2001, with no fishing recorded from the oil-affected regions of Floreana and southern Isabela in February 2001. The total fishing effort of small boats operating from the Jessica-grounding island of San Cristóbal also declined immediately after the spill, probably in part because such boats were used in clean up operations. During 2001, prices paid to fishers remained stable at levels higher than in 2000, with the notable anomaly that prices fell precipitously to 30% of previous levels during a 1-2 week period in early February 2001. Fish exports remained at similar levels for the years 2000 and 2001; however, as in the previous year, little fish product was exported from Galápagos in the month following the spill, with most fish product dried and stored for up to two months prior to transport to the continent.  相似文献   

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毛娟  邢西淳  邵辉成  王军儒 《地震工程学报》2003,25(4):370-373

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结合当前GIS技术的发展 ,讨论了COMGIS的定义、特性及原理 ,并结合实际应用 ,探讨了COMGIS的各种实现方式  相似文献   

降水对热带西南太平洋海温异常响应的数值试验   总被引：1，自引：3，他引：1       下载免费PDF全文

李娟  张铭 《气象科学》2004,24(2):154-160

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Plate kinematics, origin and tectonic emplacement of supra-subduction ophiolites in SE Asia   总被引：2，自引：0，他引：2  

Manuel Pubellier  Christophe Monnier  Ren Maury  R. Tamayo 《Tectonophysics》2004,392(1-4):9

A unique feature of the Circum Pacific orogenic belts is the occurrence of ophiolitic bodies of various sizes, most of which display petrological and geochemical characteristics typical of supra-subduction zone oceanic crust. In SE Asia, a majority of the ophiolites appear to have originated at convergent margins, and specifically in backarc or island arc settings, which evolved either along the edge of the Sunda (Eurasia) and Australian cratons, or within the Philippine Sea Plate. These ophiolites were later accreted to continental margins during the Tertiary. Because of fast relative plate velocities, tectonic regimes at the active margins of these three plates also changed rapidly. Strain partitioning associated with oblique convergence caused arc-trench systems to move further away from the locus of their accretion. We distinguish “relatively autochthonous ophiolites” resulting from the shortening of marginal basins such as the present-day South China Sea or the Coral Sea, and “highly displaced ophiolites” developed in oblique convergent margins, where they were dismantled, transported and locally severely sheared during final docking. In peri-cratonic mobile belts (i.e. the Philippine Mobile Belt) we find a series of oceanic basins which have been slightly deformed and uplifted. Varying lithologies and geochemical compositions of tectonic units in these basins, as well as their age discrepancies, suggest important displacements along major wrench faults.We have used plate tectonic reconstructions to restore the former backarc basins and island arcs characterized by known petro-geochemical data to their original location and their former tectonic settings. Some of the ophiolites occurring in front of the Sunda plate represent supra-subduction zone basins formed along the Australian Craton margin during the Mesozoic. The Philippine Sea Basin, the Huatung basin south of Taiwan, and composite ophiolitic basements of the Philippines and Halmahera may represent remnants of such marginal basins. The portion of the Philippine Sea Plate carrying the Taiwan–Philippine arc and its composite ophiolitic/continental crustal basement might have actually originated in a different setting, closer to that of the Papua New Guinea Ophiolite, and then have been displaced rapidly as a result of shearing associated with fast oblique convergence.  相似文献   

Loss on ignition: a qualitative or quantitative method for organic matter and carbonate mineral content in sediments?   总被引：5，自引：7，他引：5  

Juan I. Santisteban  Rosa Mediavilla  Enrique López-Pamo  Cristino J. Dabrio  M. Blanca Ruiz Zapata  M. José Gil García  Silvino Castaño  Pedro E. Martínez-Alfaro 《Journal of Paleolimnology》2004,32(3):287-299

Since the publication of the paper of , loss on ignition (LOI) has been widely used as a method to estimate the amount of organic matter and carbonate mineral content (and indirectly of organic and inorganic carbon) in sediments. The relationships between LOI at 550 °C (LOI₅₅₀) and organic carbon (OC) content and between LOI at 950 °C (LOI₉₅₀) and inorganic carbon (IC) content are currently accepted as a standard. However, the comparison of 150 analyses of samples of diverse lithologies, collected from a single core, reveals that these relationships are affected by sediment composition (presence of clays, salts, and the variable content of organic carbon). This results in an incremental error on the estimation of carbon content from LOI values that invalidates the use of LOI values as a quantitative method for estimating carbon content. Conversely, the general trends of LOI₅₅₀ and LOI₉₅₀ show a good correlation with carbon content (both organic and inorganic) allowing use of LOI as a qualitative test for carbon content. Similarly, in our case, LOI at 105 °C (LOI₁₀₅) is a good qualitative proxy for the trends in gypsum content.  相似文献   

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The earthquake behavior of structures with supplemental copper dampers is evaluated in this study. The investigation is divided into two parts: (i) an experimental work with seven pairs of hourglass copper dampers of different aspect ratios and side profiles; and (ii) a parametric study of 6‐, 12‐, and 25‐story planar structures with elastic as well as inelastic behavior in the primary structure and copper dampers. The copper used in this study is electrolytic tough pitch (ETP) copper C11000; probably the most commonly used of all coppers; ductile, with a low‐yield, and highly resistant to corrosion. Experimental results demonstrate that all copper plates reached stable angular distortions of the order of γ=25%, which implies transverse distortions in the devices larger than 40mm. The behavior of the devices is highly dependent on the aspect ratio of the plate, h/t, and a recommendation is made to use plates in the range 11 h/t≤18. Plates beyond this range exhibit either large stress and strain concentrations in the neck of the device or a strong influence of axial deformations in their cyclic behavior. The inelastic earthquake response of structures with such devices shows that drift reduction factors of the order of 30 to 40% can be achieved with reasonably economic designs. It is also shown that the efficiency of these devices depends on the soil conditions and flexibility of the primary structure. Finally, it is concluded that supplemental copper dampers are a good alternative for drift reduction in a wide range of structural layouts, ranging from coupled shear‐wall systems to moment‐resisting frames, and for impulsive as well as non‐impulsive ground motions. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献