El depósito de psefítas "El Peladero", en los acantilados del litoral marino de la provincia de Río Negro: Argentina
Keywords:
Pebbles, Distribution, Cliffs, Río Negro ProvinceAbstract
A conglomerate deposit in the top of the upper section of the Río Negro Formation is analyzed. This conglomerate is located in the neighbourhood of the homonym lighthhouse. Samples were taken for grain-size, morphology and origin determinations by sieving and binocular microscope observation. The deposit contains about 70% gravel, 23 to 26 % sands and the rest are silts and clays. Gravel petrology shows 76% acidic volcanic rocks while 24% are basic and intermediate rocks. The gravel tend to be discoidal to spherical in shape.. The psammitic fraction shows a dominion of fine to medium sand. The grains have sub-rounded forms and rough surfaces marked by bites and/or dimples. The depositional environment would correspond to a channelled river with strong energy and irregular variations in the flow, a process that developed during the Upper Pleistocene. The area of origin of El Peladero gravel would be the accumulated and razed plains located in the NW of Río Negro province, while the sandy levels would come from the erosion of the higher levels of the Rio Negro Formation. Moreover the age of the calcareous silt that cover the gravel is about 24.530 years BP.
Downloads
References
Andreis, R.R., 1965. Petrografía y paleocorrientes de la Fm. Río Negro (Gral. Conesa - boca del Río Negro). Revista Museo La Plata V. Geología 36: 245-310.
Auer, V., 1956. The pleistocene of The Tierra del Fuego - Patagonia. Part. I. Ann. Acad. Sci. Fenn.: 315-338.
Beltramone, C. y C. Meister, 1992. Paleocorrientes de los Rodados Patagónicos. Tramo Cdoro. Rivadavia-Trelew. Revista de la Asociación Geológica Argentina 47 (2): 147-152.
Calmels, A., S. Andreoli y L. Espizua, 1969. Naturaleza petrográfica y morfometría de los rodados patagónicos de la Isla Jabali. Prov. de Bs.As. Cuartas Jornadas Geológicas. T 1: 175-198.
Cortelezzi, C., C. Del Salvo y F. De Francesco, 1965. Estudio de las gravas tehuelches en la región comprendida entre el Río Negro y el Río Colorado desde la costa de prov. de Bs.As hasta Choele Choele. Acta Geológica Lilloana. Tucumán. T. VI: 65-87.
Cortelezzi C., F. De Francesco y C. Del Salvo, 1968. Estudio de las gravas tehuelches en la región comprendida entre el Río Negro y el Río Colorado desde la costa atlántica hasta la cordillera. Actas de las III Jornadas Geológicas Argentinas. Chubut. T III: 123-147.
De Ferrariis, C., 1966. Estudio estratigráfico de la Fm. Río Negro de la Prov. de Bs.As. Sus relaciones con la región Norpatagónica. Anales de la Comisión de Investigaciones Científicas (CIC). La Plata. Vol VII. 85-166..
Fidalgo, F. y J.C. Riggi, 1965. Los rodados patagónicos en la meseta de Guenguel y alrededores. Revista Asociación Geológica Argentina. T. 2 (3): 273–325.
Fidalgo, F. y J.C. Riggi, 1970. Consideraciones geomórficas y sedimentológicas sobre rodado patagónicos. Revista Asociación Geológica Argentina. T. 25. (4): 430-443
González Diaz, E. y E. Malagnino, 1984. Geomorfología de la provincia de Río Negro. IV Congreso Geológico Argentino. Río Negro. T. 2: 347-364.
Krumbein, W.C. and L. Sloss, 1963. Stratigraphy and sedimentation. Freeman (ed.). San Francisco.
º UTEHA. Page, R., 1987. Descripción geológica de la hoja 43 g. “Bajo de la Tierra Colorada”. Prov. del Chubut. Dirección Nacional de Geología y Minas. Buenos Aires. Bol. 200: 1-81.
Power, M., 1982. A new roundness scale for sedimentary particles. Journal Sedimentary Petrology 23: 117-119. 26
Schillizzi, R., E. Gelós, y J. Spagnuolo, 2004. Procesos de retracción de los acantilados patagónicos entre la desembocadura de los ríos Negro y Chubut. Argentina. Revista de la Asociación Argentina de Sedimentología. Vol. 11 (1): 17-26.
Stuiver, M. and H.A. Polach, 1977. Discussion: Reporting of 14C Data, Radiocarbon 19 (3): 355-363.
Suriano, J., G. Ferro y M. Dalponte, 1999. Geología y recursos minerales de la hoja 3966 - IVChoele Chole y el sector rionegrino de las hojas 3963 - III, Colonia Juliá 4163 - I - III. Gral. Conesa y 4163 - II - IV, Viedma. SEGEMAR – DMRN: 1-8.
Weber, E., 1983. Descripción geológica de la hoja 40 j “Co. El Fuerte”. Prov. de Río Negro. Servicio Geológico Nacional. Buenos Aires. Bol. 196: 1-69.
Witte, L., 1916. Descripción geológica de la región del Río Negro inferior (Parte 1). La Plata. Revista del Museo de la Plata. T. 24: 14-96.
Zavala, C y H. Freije, 2001. On the understanding of aeolian sequence stratigraphy: an example from Miocene Pleistocene deposits in Patagonia Argentina. Revista Italiana di Paleontología e Stratigrafía. 107 (2): 251-264.
Zingg, T., 1935. Beitrag zur Schotteranalyse. Schweizerische Mineral. Petrog. Mitt. Bd. 15: 39-140.
Downloads
Published
Issue
Section
License
Copyright (c) 2009 Roberto Schillizzi, Liliana Luna, Juan I. Falco
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Starting in 2022 (Vol. 43 number 2) articles will be published in the journal under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license (CC BY-NC-SA 4.0)
According to these terms, the material can be shared (copied and redistributed in any medium or format) and adapted (remixed, transformed and created from the material another work), provided that a) the authorship and the original source of its publication (journal and URL of the work), b) is not used for commercial purposes and c) the same license terms are maintained.
Prior to this date the articles were published in the journal under a Creative Commons Attribution license (CC BY)
In both cases, the acceptance of the originals by the journal implies the non-exclusive assignment of the economic rights of the authors in favor of the editor, who allows reuse, after editing (postprint), under the license that corresponds according to the edition.
Such assignment means, on the one hand, that after its publication (postprint) in the GEOACTA Magazine of the Association of Geophysicists and Geodesists, the authors can publish their work in any language, medium and format (in such cases, it is requested that it be recorded that the material was originally published in this journal); on the other, the authorization of the authors for the work to be harvested by SEDICI, the institutional repository of the National University of La Plata, and to be disseminated in the databases that the editorial team considers appropriate to increase visibility. of the publication and its authors.
Likewise, the journal encourages the authors so that after their publication in the Journal of the Association of Geophysicists and Geodesists, they deposit their productions in other institutional and thematic repositories, under the principle that offering society scientific production and Unrestricted academic scholarship contributes to a greater exchange of global knowledge.
