Evolución Paleogeográfica Del Cratón Del Río De La Plata En El Precámbrico Y Su Relación Con El Terreno Pampia En El Cámbrico

Total Page:16

File Type:pdf, Size:1020Kb

Evolución Paleogeográfica Del Cratón Del Río De La Plata En El Precámbrico Y Su Relación Con El Terreno Pampia En El Cámbrico Tesis Doctoral Evolución paleogeográfica del cratón del Río de la Plata en el Precámbrico y su relación con el Terreno Pampia en el Cámbrico Franceschinis, Pablo Reinaldo 2019 Este documento forma parte de las colecciones digitales de la Biblioteca Central Dr. Luis Federico Leloir, disponible en bibliotecadigital.exactas.uba.ar. Su utilización debe ser acompañada por la cita bibliográfica con reconocimiento de la fuente. This document is part of the digital collection of the Central Library Dr. Luis Federico Leloir, available in bibliotecadigital.exactas.uba.ar. It should be used accompanied by the corresponding citation acknowledging the source. Cita tipo APA: Franceschinis, Pablo Reinaldo. (2019). Evolución paleogeográfica del cratón del Río de la Plata en el Precámbrico y su relación con el Terreno Pampia en el Cámbrico. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. https://hdl.handle.net/20.500.12110/tesis_n6596_Franceschinis Cita tipo Chicago: Franceschinis, Pablo Reinaldo. "Evolución paleogeográfica del cratón del Río de la Plata en el Precámbrico y su relación con el Terreno Pampia en el Cámbrico". Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. 2019. https://hdl.handle.net/20.500.12110/tesis_n6596_Franceschinis Dirección: Biblioteca Central Dr. Luis F. Leloir, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Contacto: bibliotecadigital.exactas.uba.ar Intendente Güiraldes 2160 - C1428EGA - Tel. (++54 +11) 4789-9293 Universidad de Buenos Aires Facultad de Ciencias Exactas y Naturales Departamento de Ciencias Geológicas Evolución paleogeográfica del cratón del Río de la Plata en el Precámbrico y su relación con el Terreno Pampia en el Cámbrico Tesis presentada para optar al título de Doctor de la Universidad de Buenos Aires en el área de Ciencias Geológicas Lic. Pablo Reinaldo Franceschinis Director de Tesis: Dr. Augusto E. Rapalini Consejero de estudios: Dr. Augusto E. Rapalini Lugar de trabajo: Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires (IGEBA) Buenos Aires, 2019 Fecha de defensa: 14 de marzo de 2019 Evolución paleogeográfica del Cratón del Río de la Plata en el Precámbrico y su relación con el Terreno Pampia en el Cámbrico La evolución paleogeográfica del Cratón del Río de la Plata durante el Precámbrico presenta grandes interrogantes referidos a su participación en los supercontinentes proterozoicos Columbia y Rodinia y sobre su rol en la conformación del margen occidental de Gondwana en el Ediacariano a Cámbrico. A fin de aportar a la evolución paleogeográfica del cratón del Río de la Plata en el Paleoproterozoico medio, se realizaron estudios paleomagnéticos sistemáticos en plutones tardío a postectónicos en el terreno Piedra Alta (Uruguay). Estos permitieron obtener siete polos paleomagnéticos con edades entre 2.1 y 2.0 Ga que se ordenan según una curva de deriva polar aparente compatible con las edades de esos plutones y con las polaridades magnéticas obtenidas. La comparación de esta curva con las coetáneas definidas para otros cratones de América del Sur y África permite concluir que, de haber existido, el continente Atlántica tuvo una configuración muy diferente a la propuesta originalmente. En base a la nueva curva de deriva polar aparente propuesta para una configuración diferente de este continente, se presenta un modelo de evolución paleogeográfico del mismo que sugiere rápidos desplazamientos en posiciones polares en el lapso estudiado. Se llevó a cabo estudios paleomagnéticos en las Formaciones Avellaneda y Cerro Negro (Ediacariano medio a tardío) aflorantes en la localidad de Olavarría (provincia de Buenos Aires). Mientras que la segunda porta una remagnetización de probable edad pérmica, la primera permitió calcular un polo paleomagnético preliminar que sugiere una posición del cratón a altas latitudes y una posible curva de deriva polar más compleja. Esta posición polar fue 1 confirmada a partir del estudio de la Formación Avellaneda en una corona de pozo. En base a estos datos se analiza la vigencia de la curva de deriva polar aparente para el cratón aceptada en la última década, sugiriéndose la alta probabilidad de la necesidad de revisar de manera fundamental su traza. La posible presencia de un evento de desplazamiento polar verdadero en el Ediacariano medio a tardío, es analizada en función de la información paleomagnética existente y la obtenida en estos estudios. Entre los eventos finales de formación del supercontinente Gondwana en el Cámbrico se postula la anexión del terreno Pampia, con cronologías y mecanismos que han sido fuente de numerosas controversias. Se realizaron estudios paleomagnéticos en la Formación Campanario (Cámbrico Medio a Superior) en cuatro localidades de la Cordillera Oriental, así como en afloramientos de la Formación Puncoviscana, la Formación Guachos y el intrusivo Mojotoro, todos ellos del Cámbrico Inferior. Los resultados obtenidos sugieren la presencia de rotaciones tectónicas afectando varios de los afloramientos estudiados. Sin embargo, se pueden inferir paleolatitudes bajas para el terreno Pampia durante todo el Cámbrico, lo que es analizado en el marco de las incertezas correspondientes a los polos paleomagnéticos de referencia. El análisis conjunto de anomalías en declinación e inclinación observadas en la Formación Campanario sugiere que el modelo de desplazamiento y rotación del terreno Pampia desde el cratón de Kalahari hasta su posición actual durante el Cámbrico medio a tardío es improbable. Palabras claves: paleogeografía, Cratón Río de la Plata, Atlántica, Columbia, Pampia, Gondwana 2 Paleogeographic evolution of the Río de la Plata Craton in the Precambrian and its relationship with the Pampia Terrane in the Cambrian The paleogeographic evolution of the Rio de la Plata Craton during the Precambrian presents important questions regarding its participation in the Columbia and Rodinia supercontinents, and its role in the assembly of the western margin of Gondwana in the Ediacaran-Cambrian. With the aim of contributing to the paleogeographic evolution of the craton in mid-Paleoproterozoic times, systematic paleomagnetic studies were carried out in late- to post-tectonic plutons of the Piedra Alta terrane (Uruguay). These yielded nine paleomagnetic poles with ages between 2.1 and 2.0 Ga that can be interpreted as integrating a single apparent polar wander path compatible with their ages and the obtained magnetic polarities. Comparison of this path with those coeval from other South American and African cratons permits to conclude definitely that the Atlantica continent, if ever existed, had a significantly different configuration than that originally proposed. Base on the new apparent polar wander path proposed for this different continental configuration a model of its paleogeographic evolution that suggests fast displacements in polar latitudes during the study time lapse is presented. Paleomagnetic studies were carried out in the Avellaneda and Cerro Negro Formations (middle to late Ediacaran) exposed in Olavarría (Buenos Aires province). While the latter carries a remagnetization of a likely Permian age, the former allowed computing a preliminary paleomagnetic pole that suggest a high latitude for the craton and an apparent polar wander path more complex than previously envisaged. This pole position was confirmed from results of a study of the Avellaneda Formation obtained in a drill core. Based on this new data the validity of the 3 craton apparent polar wander path accepted in the last decade is analyzed, suggesting the need of a fundamental change in its trace. The posible presence of an event of true polar wander during the middle to late Ediacaran is analyzed on the basis of the already known paleomagnetic information and that obtained in this study. Among the final events of Gondwana assembly in the Cambrian, it has been postulated the accretion of the Pampia terrane, with chronologies and mechanisms that have been the source of several controversies. Paleomagnetic studies were carried out in the Campanario Formation (Middle to Upper Cambrian) at four different localities in the Eastern Cordillera. This was extended to outcrops of the Puncoviscana Fm., Guachos Fm. and the Mojotoro intrusive, all of them of Early Cambrian age. The results suggest that tectonic rotations around vertical axes affect many of the exposures. However, low paleolatitudes can be inferred for the Pampia terrane during the whole Cambrian, which is analyzed in the background of the uncertainties correspondent to the reference paleomagnetic poles. The analysis of all anomalies, both in declination and inclination, from the Campanario Formation suggests that the model of displacement and rotation of the Pampia terrane from the Kalahari craton up to its present-day position during the middle to late Cambrian is unlikely. Keywords: Paleogeography, Río de la Plata Cratón, Atlántica, Columbia, Pampia, Gondwana 4 Agradecimientos A mi director, Augusto, por su constante ayuda, consejos y enseñanzas. Por nuestras charlas de cine, literatura, historia, política, fútbol… A mi familia, mis padres Clara y Ricardo y a mi hermano Gustavo por creer siempre en mí, por su infinita paciencia y por brindarme su incondicional apoyo. A mi novia Florencia, por apoyarme día a día. Por su cariño y por hacerme reír cuando estaba cansado o preocupado. Al grupo de becarios del INGEODAV “La Generación Dorada”. Por hacer amenos estos cinco años de beca, con incontables asados, salidas, conversaciones,
Recommended publications
  • Late Quaternary Morphodynamics in the Quebrada De Purmamarca, NW Argentina
    Quaternary Science Journal GEOZON SCIENCE MEDIA Volume 59 / Number 1–2 / 2010 / 21–35 / DOI 10.3285/eg.59.1-2.02 ISSN 0424-7116 E&G www.quaternary-science.net Late Quaternary morphodynamics in the Quebrada de Purmamarca, NW Argentina Jan-Hendrik May, Ramiro Daniel Soler Abstract: � This study aims to document the geomorphic, sedimentary and paleopedogenic archives in the Quebrada de Purmamarca.The paleoenvironmental interpretation of these archives and the reconstruction of landscape evolution are mainly based on field observations and geomorphological mapping (May 2008). A series of aggradational terraces mostly consisting of coarse debris- flow deposits are the main focus of this investigation. While the associated cut-and-fill processes are probably the result of an interplay between climatic and tectonic controls, the deposition of the youngest terrace level (> 150 m thickness) may likely be attributed to a drop of the periglacial belt of more than 1000 meters below its modern elevation. For the time after terraceac- cumulation has ceased, the interpretation of alluvial fans, aeolian sand and a well-developed paleosol points to Late Quaternary humidity changes as an important control on landscape evolution. The major phase of downcutting and incision significantly postdates the end of terrace deposition and may have been triggered by markedly increased amounts of monsoonal precipita- tion. Finally, minor humidity changes of possible Holocene age are indicated by paleopedogenic and geomorphic observations on terrace surfaces and along valley slopes. (Spätquartäre Morphodynamik in der Quebrada de Purmamarca, NW Argentina) Kurzfassung: Ziel dieser Arbeit ist die Dokumentation geomorphologischer, sedimentärer und paläopedologischer Archive in der Quebrada de Purmamarca.
    [Show full text]
  • Presentación De Powerpoint
    S11D-0385: Three major faults in northeastern Colombia (Sierra Nevada de Santa Marta & Perija Range): seismotectonic model and scope of its seismic hazard Germán Chicangana 1, Andreas Kammer 2, Hector Mora - Páez 3, Carlos Alberto Vargas 2, Augusto Gómez - Capera 4. 1. Universidad Santo Tomas, Villavicencio, Colombia. 2. Universidad Nacional de Colombia, Bogotá D.C., Colombia. 3. Servicio Geológico Colombiano, Bogotá D.C., Colombia. 4..Istituto Nazionale di Geofísica e Vulcanologia, Milano, Italy. ABSTRACT 2. REGIONAL GEOLOGY 3. HISTORICAL EARTHQUAKE In the northeasternCORO Colombia, the northernmost foothills of the Andes are present, whose representatives are 1. LOCATION the Sierra Nevada de Santa Marta (SNSM) and the Perija Range. This orogenic system is delimited by three major faults that limit three large basins. In its order from west to east are the Santa Marta Fault that limits the Sierra Nevada de Santa Marta with the Lower Magdalena Basin. The Oca Fault that limits with the low basin of the Rancheria River to the north in the south of Guajira Peninsula, and toward the east the Perija – El Tigre Fault that limits with the Maracaibo Basin. Each of these faults have a great size. Since 2008, when the National Seismological Network of Colombia (RSNC) increased its number of seismological stations in this region of Colombia, the recording of surface seismicity that is associated with the tectonic mobility of this orogenic system began. The strong earthquakes in this region do not exceed in magnitude M = 5.5, emphasizing earthquakes with M ≈ 4.5 in average. The origin of the tectonic mobility of this orogenic system obeys to the convergence between the Caribbean Plate and the northwestern corner of South America.
    [Show full text]
  • Mesh-Based Tectonic Reconstruction: Andean Margin Evolution Since the Cretaceous
    Mesh-based tectonic reconstruction: Andean margin evolution since the Cretaceous Tomas P. O'Kane, Gordon S. Lister Journal of the Virtual Explorer, Electronic Edition, ISSN 1441-8142, volume 43, paper 1 In: (Eds.) Stephen Johnston and Gideon Rosenbaum, Oroclines, 2012. Download from: http://virtualexplorer.com.au/article/2011/297/mesh-based-tectonic-reconstruction Click http://virtualexplorer.com.au/subscribe/ to subscribe to the Journal of the Virtual Explorer. Email [email protected] to contact a member of the Virtual Explorer team. Copyright is shared by The Virtual Explorer Pty Ltd with authors of individual contributions. Individual authors may use a single figure and/or a table and/or a brief paragraph or two of text in a subsequent work, provided this work is of a scientific nature, and intended for use in a learned journal, book or other peer reviewed publication. Copies of this article may be made in unlimited numbers for use in a classroom, to further education and science. The Virtual Explorer Pty Ltd is a scientific publisher and intends that appropriate professional standards be met in any of its publications. Journal of the Virtual Explorer, 2012 Volume 43 Paper 1 http://virtualexplorer.com.au/ Mesh-based tectonic reconstruction: Andean margin evolution since the Cretaceous Tomas P. O'Kane Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia. Email: [email protected] Gordon S. Lister Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia. Abstract: In this contribution we demonstrate an example of what can be described as mesh-based tectonic reconstruction.
    [Show full text]
  • 4 Three-Dimensional Density Model of the Nazca Plate and the Andean Continental Margin
    76 4 Three-dimensional density model of the Nazca plate and the Andean continental margin Authors: Andrés Tassara, Hans-Jürgen Götze, Sabine Schmidt and Ron Hackney Paper under review (September 27th, 2005) by the Journal of Geophysical Research Abstract We forward modelled the Bouguer anomaly in a region encompassing the Pacific ocean (east of 85°W) and the Andean margin (west of 60°W) between northern Peru (5°S) and Patagonia (45°S). The three-dimensional density structure used to accurately reproduce the gravity field is simple. The oceanic Nazca plate is formed by one crustal body and one mantle lithosphere body overlying a sub-lithospheric mantle, but fracture zones divide the plate into seven along-strike segments. The subducted slab was modelled to a depth of 410 km, has the same structure as the oceanic plate, but it is subdivided into four segments with depth. The continental margin consists of one upper-crustal and one lower-crustal body without lateral subdivision, whereas the mantle has two bodies for the lithosphere and two bodies for the asthenosphere that are separated across-strike by the downward prolongation of the eastern limit of active volcanism. We predefined the density for each body after studying its dependency on composition of crustal and mantle materials and pressure-temperature conditions appropriate for the Andean setting. A database containing independent geophysical information constrains the geometry of the subducted slab, locally the Moho of the oceanic and continental crusts, and indirectly the lithosphere-asthenosphere boundary (LAB) underneath the continental plate. Other geometries, especially that of the intracrustal density discontinuity (ICD) in the continental margin, were not constrained and are the result of fitting the observed and calculated Bouguer anomaly during the forward modelling.
    [Show full text]
  • Crustal-Seismicity.Pdf
    Tectonophysics 786 (2020) 228450 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Crustal seismicity in the Andean Precordillera of Argentina using seismic broadband data T ⁎ Agostina Venerdinia,b, , Patricia Alvaradoa,b, Jean-Baptiste Ammiratia,1, Marcos Podestaa, Luciana Lópezc, Facundo Fuentesd, Lepolt Linkimere, Susan Beckf a Grupo de Sismotectónica, Centro de Investigaciones de la Geósfera y la Biósfera (Consejo Nacional de Investigaciones Científicas y Técnicas CONICET– Facultad de Ciencias Exactas, Físicas y Naturales, UNSJ), San Juan, Argentina b Departamento de Geofísica y Astronomía, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, San Juan, Argentina c Instituto Nacional de Prevención Sísmica, San Juan, Argentina d YPF S.A., Buenos Aires, Argentina e Escuela Centroamericana de Geología, Universidad de Costa Rica, San José, Costa Rica f Department of Geosciences, University of Arizona, Tucson, AZ, United States ARTICLE INFO ABSTRACT Keywords: In this study, we analyze 100 crustal Precordilleran earthquakes recorded in 2008 and 2009 by 52 broadband Crust seismic stations from the SIEMBRA and ESP, two temporary experiments deployed in the Pampean flat slab Focal mechanism region, between the Andean Cordillera and the Sierras Pampeanas in the Argentine Andean backarc region. Fold-thrust belt In order to determine more accurate hypocenters, focal mechanisms and regional stress orientations, we Andean retroarc relocated 100 earthquakes using the JHD technique and a local velocity model. The focal depths of our relocated Flat slab events vary between 6 and 50 km. We estimated local magnitudes between 0.4 ≤ M ≤ 5.3 and moment South America L magnitudes between 1.3 ≤ Mw ≤ 5.3.
    [Show full text]
  • Seismic Hazard, Risk, and Design for South America by Mark D
    Bulletin of the Seismological Society of America, Vol. 108, No. 2, pp. 781–800, April 2018, doi: 10.1785/0120170002 Seismic Hazard, Risk, and Design for South America by Mark D. Petersen, Stephen C. Harmsen, Kishor S. Jaiswal, Kenneth S. Rukstales, Nicolas Luco, Kathleen M. Haller, Charles S. Mueller, and Allison M. Shumway Abstract We calculate seismic hazard, risk, and design criteria across South America using the latest data, models, and methods to support public officials, sci- entists, and engineers in earthquake risk mitigation efforts. Updated continental scale seismic hazard models are based on a new seismicity catalog, seismicity rate models, evaluation of earthquake sizes, fault geometry and rate parameters, and ground- motion models. Resulting probabilistic seismic hazard maps show peak ground accel- eration, modified Mercalli intensity, and spectral accelerations at 0.2 and 1 s periods for 2%, 10%, and 50% probabilities of exceedance in 50 yrs. Ground shaking soil amplification at each site is calculated by considering uniform soil that is applied in modern building codes or by applying site-specific factors based on VS30 shear- wave velocities determined through a simple topographic proxy technique. We use these hazard models in conjunction with the Prompt Assessment of Global Earth- quakes for Response (PAGER) model to calculate economic and casualty risk. Risk is computed by incorporating the new hazard values amplified by soil, PAGER fra- gility/vulnerability equations, and LandScan 2012 estimates of population exposure. We also calculate building design values using the guidelines established in the build- ing code provisions. Resulting hazard and associated risk is high along the northern and western coasts of South America, reaching damaging levels of ground shaking in Chile, western Argentina, western Bolivia, Peru, Ecuador, Colombia, Venezuela, and in localized areas distributed across the rest of the continent where historical earth- quakes have occurred.
    [Show full text]
  • Geophysical Evidence for Terrane Boundaries in South-Central Argentina Carlos J
    Gondwana Research, G! 7, No. 4, pp. 1105-1 116. 0 2004 International Association for Gondwana Research, Japan. ISSN: 1342-937X Geophysical Evidence for Terrane Boundaries in South-Central Argentina Carlos J. Chernicoff and Eduardo 0. Zappettini2 Council for Scientific and Technical Research (CONICET),Universidad de Buenos Aires, E-mail: [email protected] ' Argentine Geological-Mining Survey (SEGEMAR). Av. Julio A. Roca 651, 8" piso, (1322) Buenos Aires, Argentina, E-mail: [email protected] * Corresponding author (Manuscript received July 24,2003; accepted January 26,2004) Abstract The geological interpretation of high-resolution aeromagnetic data over the La Pampa province, in central Argentina, in addition to lower resolution magnetic information from the region of the Neuquen and Colorado basins, leads to the definition of the precise boundaries of the Chilenia, Cuyania, Pampia and Patagonia terranes, as well as that of the Rio ..... de la Plata Craton, within the study region. The high-resolution aeromagnetic survey data are compared and studied in conjunction with all the available geological information, to produce a map of the solid geology of this region, which is largely covered by Quaternary sediments. A number of structures of different magnitudes, as we11 as their relative chronology, are also recognized, i.e., regional faults, sub-regional faults, fractures and shear zones, as well as the most conspicuous magnetic fabric of the basement that reflects its main planar structures. Three different basements are distinguished on the basis of their contrasting magnetic character, and are interpreted to represent the Cuyania and Pampia terranes and the Rio de la Plata Craton, separated from each other by large-scale discontinuities.
    [Show full text]
  • PDF Linkchapter
    Index Page numbers in italic denote Figures. Page numbers in bold denote Tables. Abanico extensional basin 2, 4, 68, 70, 71, 72, 420 Andacollo Group 132, 133, 134 basin width analogue modelling 4, 84, 95, 99 Andean margin Abanico Formation 39, 40, 71, 163 kinematic model 67–68 accommodation systems tracts 226, 227, 228, 234, thermomechanical model 65, 67 235, 237 Andean Orogen accretionary prism, Choapa Metamorphic Complex development 1, 3 20–21, 25 deformation 1, 3, 4 Aconcagua fold and thrust belt 18, 41, 69, 70, 72, 96, tectonic and surface processes 1, 3 97–98 elevation 3 deformation 74, 76 geodynamics and evolution 3–5 out-of-sequence structures 99–100 tectonic cycles 13–43 Aconcagua mountain 3, 40, 348, 349 uplift and erosion 7–8 landslides 7, 331, 332, 333, 346–365 Andean tectonic cycle 14,29–43 as source of hummocky deposits 360–362 Cretaceous 32–36 TCN 36Cl dating 363 early period 30–35 aeolian deposits, Frontal Cordillera piedmont 299, Jurassic 29–32 302–303 late period 35–43 Aetostreon 206, 207, 209, 212 andesite aggradation 226, 227, 234, 236 Agrio Formation 205, 206, 207, 209, 210 cycles, Frontal Cordillera piedmont 296–300 Chachahue´n Group 214 Agrio fold and thrust belt 215, 216 Neuque´n Basin 161, 162 Agrio Formation 133, 134, 147–148, 203, Angualasto Group 20, 22, 23 205–213, 206 apatite ammonoids 205, 206–211 fission track dating 40, 71, 396, 438 stratigraphy 33, 205–211 (U–Th)/He thermochronology 40, 75, 387–397 Agua de la Mula Member 133, 134, 205, 211, 213 Ar/Ar age Agua de los Burros Fault 424, 435 Abanico Formation
    [Show full text]
  • A History of Proterozoic Terranes in Southern South America: from Rodinia to Gondwana
    + MODEL GEOSCIENCE FRONTIERS -(-) (2011) 1e9 available at www.sciencedirect.com China University of Geosciences (Beijing) GEOSCIENCE FRONTIERS journal homepage: www.elsevier.com/locate/gsf REVIEW A history of Proterozoic terranes in southern South America: From Rodinia to Gondwana C. Casquet a,*, C.W. Rapela b, R.J. Pankhurst c, E.G. Baldo d, C. Galindo a, C.M. Fanning e, J.A. Dahlquist d, J. Saavedra f a Departamento de Petrologıa y Geoquımica, IGEO (Universidad Complutense, CSIC), 28040 Madrid, Spain b Centro de Investigaciones Geologicas (CONICET-UNLP), 1900 La Plata, Argentina c Visiting Research Associate, British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom d CICTERRA (CONICET-UNC), 5000 Cordoba, Argentina e Research School of Earth Sciences, The Australian National University, Canberra, Australia f Instituto de Agrobiologıa y Recursos Naturales CSIC, 37071 Salamanca, Spain Received 3 August 2011; accepted 8 November 2011 KEYWORDS Abstract The role played by Paleoproterozoic cratons in southern South America from the Mesopro- Paleoproterozoic; terozoic to the Early Cambrian is reconsidered here. This period involved protracted continental amal- Cratons; gamation that led to formation of the supercontinent Rodinia, followed by Neoproterozoic continental Grenvillian; break-up, with the consequent opening of Clymene and Iapetus oceans, and finally continental Neoproterozoic rifting; re-assembly as Gondwana through complex oblique collisions in the Late Neoproterozoic to Early SW Gondwana assembly Cambrian. The evidence for this is based mainly on a combination of precise U-Pb SHRMP dating and radiogenic isotope data for igneous and metamorphic rocks from a large area extending from the Rio de la Plata craton in the east to the Argentine Precordillera in the west and as far north as Arequipa in Peru.
    [Show full text]
  • The Gondwana Margin: Proterozoic to Mesozoic
    CORE Metadata, citation and similar papers at core.ac.uk Provided by EPrints Complutense The Gondwana margin: Proterozoic to Mesozoic The longevity and extent of the oceanic southern of '--'H��'.JAJ.J.'u., E. I.M. Gonzalez-Casado and I.A. Dahlquist Gondwana have made it the of intense study for more on "The Maz terrane: a Mesoproterozoic domain in the western than 70 years. It was one of the cradles of terrane and Sierras equivalent to the remains a proving ground for theories of Antofalla block of southern Peru? for West LL.L�""".LE, """'.LJL.LU''-'H and Investigation on this Gondwana evolution" sheds new light on the Middle margin, such as accretionary orogenesis and terrane analysis, is and Late Proterozoic evolution of the western Amazonia margin vital to our understanding of the Proterozoic and Phanerozoic that preceded final amalgamation of West Gondwana in the Late evolution of the continental crust. In this issue of Cambrian. The Maz terrane Gondwana Research, entitled "The West Gondwana Margin: Sierras Pampeanas) is recognised as a new continental terrane Proterozoic to Mesozoic", we have assembled 9 research papers that underwent Grenvillian-age orogeny and was thoroughly various of the evolution of the West the Ordovician Famatinian orogeny. Nd- and Gondwana margin, frrst at the international .L.Ln-''-'�'J.�F. allows correlation of Maz metasedi­ 'Gondwana 12 (Geological and Biological Heritage of Gond- rnp'nt�n"\T rocks with the Mesoproterozoic northern part of the wana)', held in in November 2005. Many -'-'J.�V.L<-"HU craton, of pre-Andean basement in concern southern South which has a continuous southern Peru.
    [Show full text]
  • The Argentine Precordillera: a Foreland Thrust Belt Proximal to the Subducted Plate
    The Argentine Precordillera: A foreland thrust belt proximal to the subducted plate Richard W. Allmendinger and Phoebe A. Judge Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York 14853, USA ABSTRACT of constructing balanced cross sections with- thickening in the lower crust, much as described out worrying about exactly where lower crustal by Bird (1988) for the Laramide Rocky Moun- The Precordillera thrust belt of west- shortening commences, how the transition from tain foreland of the western United States. ern Argentina is anomalously close, both upper crustal to whole crust shortening occurs, horizontally and vertically, to the coeval or even how the thrust plates will restore relative TECTONIC AND GEOLOGIC SETTING subduction zone of the Nazca plate. The to the trench. thin-skinned part of the belt has an unusu- The Precordillera thrust belt of western The Argentine Precordillera overlies a region ally deep décollement that is well defi ned by Argentina, in contrast, is located 350 km from of fl at subduction of the Nazca plate (Cahill industry seismic refl ection and recent broad- the Chile Trench and just 100 km above the and Isacks, 1992; Gans et al., 2011) located at band experiments. New area and line-length subducted Nazca plate. Thus the amount of the southern end of the Central Andes (Fig. 1). balanced cross sections show that the cen- crust to work with when attempting to bal- This region of fl at subduction has been linked tral Precordillera has accrued ~90 ± 21 km ance the shortening in the thrust belt is signifi - to the subduction of the Juan Fernández Ridge, of shortening since 13 Ma; much of that cantly less than elsewhere, raising questions which, because of a dogleg in its now sub- shortening occurred between 12 and 9 Ma.
    [Show full text]
  • U-Pb Geochronology and Paleogeography of the Valanginian– Hauterivian Neuquén Basin: Implications for Gondwana-Scale
    Research Paper GEOSPHERE U-Pb geochronology and paleogeography of the Valanginian– Hauterivian Neuquén Basin: Implications for Gondwana-scale GEOSPHERE, v. 17, no. 1 source areas https://doi.org/10.1130/GES02284.1 E. Schwarz1,*, E.S. Finzel2,*, G.D. Veiga1, C.W. Rapela1, C. Echevarria3,*, and L.A. Spalletti1 1Centro de Investigaciones Geológicas (Universidad Nacional de La Plata–Consejo Nacional de Investigaciones Científicas y Técnicas [CONICET]), Diagonal 113 #256 B1904DPK, La Plata, Argentina 13 figures; 2 tables; 1 set of supplemental files 2Earth and Environmental Science Department, University of Iowa, 115 Trowbridge Hall, Iowa City, Iowa 52242, USA 3Pampa Energía S.A. Gerencia Tight, Dirección de E&P, J.J. Lastra 6000, 8300 Neuquén, Argentina CORRESPONDENCE: [email protected] ABSTRACT starting in the mid-continent region of south- Early Cretaceous was the Neuquén Basin, which CITATION: Schwarz, E., Finzel, E.S., Veiga, G.D., western Gondwana and by effective sorting, was during that time was a backarc basin separated Rapela, C.W., Echevarria, C., and Spalletti, L.A., Sedimentary basins located at the margins bringing fine-grained or finer caliber sand to the from the proto–Pacific Ocean (i.e., to the west) by 2021, U-Pb geochronology and paleogeography of the of continents act as the final base level for con- Neuquén Basin shoreline. This delivery system was a discontinuous volcanic arc (Howell et al., 2005). Valanginian–Hauterivian Neuquén Basin: Implications for Gondwana-scale source areas: Geosphere, v. 17, tinental-scale catchments that are sometimes probably active (though not necessarily continu- This marine basin was bounded by the Sierra no.
    [Show full text]