The spatial structure of lithic landscapes : the late holocene record of east-central Argentina as a case study

Fil: Barrientos, Gustavo. División Antropología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Catella, Luciana. División Arqueología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Oliva, Fernando. Centro Estudios Arqueológicos Regionales. Facultad de Humanidades y Artes. Universidad Nacional de Rosario; Argentin

Géodynamique andine : résumé étendus = Andean geodynamics : extended abstracts

Au Paléozoïque inférieur à moyen, le S.O. de l'Amérique du Sud a subi un cycle orogénique complet, depuis un état d'avant-collision, passant par une collision continent-continent et se terminant par un soulèvement. La collision (depuis 460 Ma et jusqu'à 440 Ma, ou alors 420 Ma) est responsable de la chaîne orogénique famatinienne, développée à l'est de la Cordillère mésozoïque andine. D'ouest en est, les unités tectoniques étaient trois : le terrain exotique d'Occidentalia, la chaîne famatinienne et le craton de La Plata-Brésil-Afrique. (Résumé d'auteur

Application of pneumatic method to build vulnerability curves in solitary vesselled trees: Assessement of vulnerability to cavitation of three Eucalyptus mature tree species

Air entry in the plant water-transport system leads to vascular embolism that has a major impact on plant water relations by disrupting the water-transport capacity, impairing its functioning and even triggering the plant death. Forestry tree species should exhibit both high survival and fast growth rate. From this point of view, Eucalyptus is an interesting genus since it inhabits a wide diversity of climatic and environmental conditions and covers more than 20 million planted hectares worldwide. This genus presents solitary vessels, i.e. not directly connected to other vessels but surrounded by different imperforate tracheary elements and parenchyma that participate in a less known form in xylem safety and hydraulic efficiency

Application of pneumatic method to build vulnerability curves in solitary vesselled trees: Assessement of vulnerability to cavitation of three Eucalyptus mature tree species

Air entry in the plant water-transport system leads to vascular embolism that has a major impact on plant water relations by disrupting the water-transport capacity, impairing its functioning and even triggering the plant death. Forestry tree species should exhibit both high survival and fast growth rate. From this point of view, Eucalyptus is an interesting genus since it inhabits a wide diversity of climatic and environmental conditions and covers more than 20 million planted hectares worldwide. This genus presents solitary vessels, i.e. not directly connected to other vessels but surrounded by different imperforate tracheary elements and parenchyma that participate in a less known form in xylem safety and hydraulic efficiency

A comparison of five methods to assess embolism resistance in trees

Vulnerability to drought-induced embolism is a key trait that shapes drought resistance and that could be increasingly used to design climate-smart forest management guidelines and to anticipate the outcome of climate change on populations dynamics and ecosystems functioning. A panel of methods is currently available to measure embolism resistance. This makes crucial a proper identification of which methods are the most accurate for determining this trait. However, the measurement of embolism resistance is sensitive to numerous artifacts that may lead to large errors for a given species. In addition, not all methods are easily accessible because of the cost of some large equipment and/or certain lab facilities. The emergence of the easy and low cost Pneumatic method allows to perform vulnerability curves at high throughput. However, only few studies have evaluated the reliability of this method compared to others. In this study, we proposed a comparison of five methods that allowed to assess embolism resistance in eleven tree species with contrasting xylem anatomy and vessels length (six short vessel angiosperms, two tracheid bearing conifers and three long-vessel angiosperms), covering a large part of the range of embolism resistance observed in trees. Consistent results were obtained among all the methods for short-vessel angiosperm species. In tracheid-bearing conifers, the Pneumatic method overestimated vulnerability to embolism. In long-vessel species, the Pneumatic method led to inconsistent results with accurate vulnerability to cavitation curves (VCs) for one species but led to r-shaped VCs with a underestimation of incipient embolism for the two other ones. The comparison of VC parameters with turgor loss point is proposed as an indicator of the validity of the VCs. The conditions of validity, the advantages and pitfalls of the five methods are discussed. Our results warned against the widespread usages of some methods before rigorous validation tests have been performed

Structural evolution of a composite middle to lower crustal section: The Sierra de Pie de Palo, northwest Argentina.

The Sierra de Pie de Palo of northwest Argentina preserves middle to lower crustal metamorphic rocks that were penetratively deformed during Ordovician accretion of the Precordillera terrane to the Gondwana margin. New structural, petrologic, and geochronologic data from a 40 km structural transect reveals that the Sierra de Pie de Palo preserves a middle to lower crustal ductile thrust complex consisting of individual structural units and not an intact ophiolite and cover sequence. Top-to-the-west thrusting occurred intermittently on discrete ductile shear zones from ∼515 to ∼417 Ma and generally propagated toward the foreland with progressive deformation. Ordovician crustal shortening and peak metamorphic temperatures in the central portion of the Sierra de Pie de Palo were synchronous with retro-arc shortening and magmatic flare-up within the Famatina arc. Accretion of the Precordillera terrane resulted in the end of arc flare-up and the onset of synconvergent extension by ∼439 Ma. Continued synextensional to postextensional convergence was accommodated along progressively lower grade shear zones following terrane accretion and the establishment of a new plate margin west of the Precordillera terrane. The results support models of Cordilleran orogens that link voluminous arc magmatism to periods of regional shortening. The deformation, metamorphic, and magmatic history within the Sierra de Pie de Palo is consistent with models placing the region adjacent to the Famatina margin in the middle Cambrian and not as basement to the Precordillera terrane.Fil: Mulcahy, S. R.. University of Nevada; Estados Unidos. University of California at Davis; Estados UnidosFil: Roeske, S. M.. University of California at Davis; Estados UnidosFil: McClelland, W. C.. University of Iowa; Estados UnidosFil: Jourdan, F.. Curtin University; Australia. Berkeley Geochronology Center; Estados UnidosFil: Iriondo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Renne, P. R.. Berkeley Geochronology Center; Estados Unidos. University of California at Berkeley; Estados UnidosFil: Vervoort, J. D.. Washington State University; Estados UnidosFil: Vujovich, Graciela Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin