Laurentian cambrian trilobites of la Laja Formation, San Juan precordillera, Argentina: A biogeographic approach to the allochthonous precordillera model [Trilobites laurénticos de la formación la laja (cámbrico), precordillera de San Juan, Argentina: Un aporte biogeográfico al modelo alóctono de precordillera]
Bordonaro O.L.,IANIGLA CCT
Revista de la Asociacion Geologica Argentina | Year: 2016
The biogeographic distribution of 14 laurentian ptychoparioid trilobite of the La Laja Formation, Middle Cambrian (Series 3) from the San Juan Precordillera, western Argentina is analyzed. The trilobites were endemic Laurentian species with restricted access to open oceans that inhabited the inner parts of the carbonate platform that rimmed the North American craton. Its presence in the restricted carbonatic platform of the Argentine Precordillera and its absence in the carbonatic facies of East Gondwana, particularly in Antarctica – Australia, are incompatible with dispersal by oceanic equatorial currents across an Iapetus open ocean in a Cuyania para- autochthonous gondwanan model. Instead, it is compatible with peri-laurentian dispersion in an allochthonous laurentian model, but only if Cuyania was environmentally connected to southern Laurentia. A modified allochthonous Laurentian model where the northern Cuyania is physically and environmentally connected to the southern Appalachians is proposed to explain the dispersion of endemic faunas without having to cross an open ocean. © 2016, Asociacion Geologica Argentina. All rights reserved.
Branham R.L.,IANIGLA CCT
Astronomische Nachrichten | Year: 2012
Comet C/1853 E1 (Secchi) has a hyperbolic orbit with eccentricity 1.01060 and perihelion outside of the Earth's orbit. Integrating the orbit with barycentric coordinates backwards to 50000 AU, the approximate edge of the Oort cloud, shows that the orbit remains hyperbolic. This is still true even if plutoids additional to Pluto are included in the integration. Nor does including Galactic tidal and disc effects and possible nongravitational forces change the orbit to a high eccentricity ellipse. Although certain factors, such as unknown massive plutoids, gravitational effects by interstellar gas clouds, or unmodelled nongravitational forces operating on the comet, could change this situation, the tentative conclusion that the origin of this comet is extrasolar remains the one most consistent with the observations. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Branham R.L.,IANIGLA CCT
Astronomische Nachrichten | Year: 2014
A new orbit for comet C/1858 L1 (Donati), based on 1036 observations in α and 971 in σ made between 7 June 1858 and 5 March 1859, is calculated using iteratively reweighted least squares. Residuals were weighted by the Welsch weighting function. The orbit represents a high eccentricity ellipse, e = 0.996265, with large semi-major axis, a = 154.8612 AU, and long period, P = 1927.22 yr. The residuals are relatively random, a 10.7% chance of being random, but with a slight indication of possible nongravitational forces influencing the motion. The comet will not return until the year 3759, when it will pass 0.8442 AU from the Earth. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Santos J.R.,National University of Cuyo |
Norte F.,Programa Regional de Meteorologia PRM |
Moreiras S.,IANIGLA CCT |
Araneo D.,Programa Regional de Meteorologia PRM |
Simonelli S.,Programa Regional de Meteorologia PRM
Geoacta (Argentina) | Year: 2015
Precipitation prediction on complex terrain, especially where the soil is vulnerable for landslides occurrence, is an important tool to prevent accidents. Severe storms along the 7 International Route that connects Argentina with Pacific Ocean (Chile) causes debris flow and landslides interrupting the international traffic. Sometimes, if the episode is severe, the blocking is large generating commercial problems and danger for the people. The principal aim of this paper is to analyze the relevant synoptic conditions that favour the occurrence of landslides and a secondary objective is to evaluate the ability of regional models such as the Weather Research and Forecasting (WRF) and Eta/MRP (Meteorological Regional Program) to predict precipitation events in a complex terrain area with a meteorological network of low density. Four events that ocasioned landslides were analyzed, namely March 27th 2007, January 13th 2013, February 7th and 8th 2013 and February 25th 2014. Negative anomaly of zonal wind between 850 hPa and 400 hPa level is one of the common synoptic characteristics for these episodes analyzed. Forecast validation was carried out by using surface data from a meteorological network of National Weather Service of Argentina, Irrigation Bureau of Mendoza province and the precipitation estimation by the CMORPH method (Joyce et al., 2004). It was observed that numerical models can predict these heavy precipitating events however with an overestimation. It worth noting that CMORPH is a good tool to estimate precipitation in mountainous terrain. © 2015 Asociación Argentina de Geofísicos y Geodestas.
Branham R.L.,IANIGLA CCT
Astronomische Nachrichten | Year: 2011
Comet C/1857 D1 (d'Arrest) is one of a large number of comets with parabolic orbits. Given that there are sufficient observations of the comet, 299 in right ascension and 279 in declination, it proves possible to calculate a better orbit. The calculations are based on a 12th order predictor-corrector method. The comet's orbit is highly elliptical, e = 0.99982 and, from calculated mean errors, statistically different from a parabola. The comet will not return for at least 44000 years and thus represents no immediate NEO threat. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.