DOCSLIB.ORG

Investigation of the Effects of Nazca-South America

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Investigation of the Effects of Nazca-South America Investigation of the Effects of Nazca-South America Plate Collision along the Peruvian-Chilean Active Continental Margin through Teleseismic Receiver Function Analysis Item Type text; Electronic Dissertation Authors Bishop, Brandon Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 10/10/2021 22:07:29 Link to Item http://hdl.handle.net/10150/627698 INVESTIGATION OF THE EFFECTS OF NAZCA-SOUTH AMERICA PLATE COLLISION ALONG THE PERUVIAN-CHILEAN ACTIVE CONTINENTAL MARGIN THROUGH TELESEISMIC RECEIVER FUNCTION ANALYSIS by Brandon T. Bishop __________________________ Copyright © Brandon T. Bishop 2018 A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2018 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of the requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that an accurate acknowledgement of the source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: Brandon T. Bishop 3 ACKNOWLEDGEMENTS I thank my advisors, George Zandt and Susan Beck, for supporting me and providing a sounding board for my ideas during my time here and tolerating my long and somewhat winding path to finishing. I further thank the other members of my committee, Randy Richardson, Paul Kapp, and Rick Bennett for their help and insights. I also thank my co-authors and co-workers in the U.S., Peru, and Bolivia who have helped both in the deployment of seismometers and collection of seismic data from the Central Andean Uplift and the Geodynamics of High Topography Experiment and the Peru Lithosphere and Slab Experiment as well as in subsequent discussions of results. Estella Minaya, Gonzalo Antonio Fernández Marañon and the other members of the Observatorio San Calixto and Jamie Tito in Bolivia; Hernando Tavera, Cristóbal Condori and the other members of the Instituto Geofísico del Perú, Maureen Long, Lara Wagner, Caroline Eakin, Abhash Kumar, Sanja Knezevic Antonijevic, Oak Rankin, Ryan Porter, Mallory Morell and a number of undergraduate research assistants from the University of Arizona, the University of North Carolina, and Yale University in Peru; and the various families, schools & hospital staffs, and at least one police department, who helped to watch over seismometers in both Bolivia and Peru. For a range of practical and intellectual reasons, none of this work would have been possible without all of their help. I also thank Carol Schwalbe, Vance T. Holliday, Charlotte Pearson, and Pamela Pelletier for the very different perspectives on science which have shaped my own. I further thank by friends and fellow grad students in Tucson especially Jamie and Stephanie Ryan, Alissa Scire, Daniel Portner and the rest of the Global Seismology and Tectonics research group. I thank Mark and Nadine Bishop, Li Guojie, and Zhang Shufen, my parents of one form or another who have all contributed their support and assistance during my time in grad school. And finally, I thank Li Jianmei, who’s help, patience, love, and support has made this possible. “Queda, naturalmente, el problema de la materia de algunos objetos.” --Jorge Luis Borge, “Tlön, Uqbar, Orbis Tertius” “Tout est pour le mieux dans le meilleur des mondes possibles.” --François-Marie Arouet, Candide, ou l’Optimisme 4 TABLES OF CONTENTS LIST OF ILLUSTRATIONS ...............................................................................................8 ABSTRACT .........................................................................................................................9 INTRODUCTION .............................................................................................................11 SUMMARY OF WORK....................................................................................................23 FIGURES ...........................................................................................................................28 REFERENCES ..................................................................................................................35 APPENDIX A: CAUSES AND CONSEQUENCES OF FLAT-SLAB SUBDUCTION IN SOUTHERN PERU ............................................................................48 ABSTRACT .............................................................................................49 INTRODUCTION ....................................................................................50 SOUTHERN PERUVIAN FLAT SLAB .................................................52 DATA AND METHODS .........................................................................54 INTERPRETATIONS OF CROSS SECTIONS ......................................56 SUMMARY MOHO MAPS ....................................................................63 DISCUSSION ..........................................................................................67 Causes of Flat-Slab Subduction in Southern Peru ...................68 Coupling of the Nazca and South American Plates .................73 Effects of Flat-Slab Subduction on the Upper Plate ................74 CONCLUSIONS ......................................................................................78 ACKNOWLEDGEMENTS .....................................................................80 REFERENCES CITED ............................................................................81 FIGURES .................................................................................................97 SUPPLEMENTAL MATERIAL ...........................................................107 RECEIVER FUNCTION METHOD DETAILS ...................107 5 DISTINGUISHING PRIMARY (Ps) RF ARRIVALS OF DEEP (50-100KM) STRUCTURE FROM CRUSTAL MULTIPLE (PpPs) ARRIVALS ...........................................108 DISTINGUISHING SUBDUCTED OCEANIC MOHO AND CONTINENTAL MOHO OF THE OVERRIDING PLATE ................................................................................................113 EFFECTS OF BIN SHARING AND STATION COVERAGE ................................................................................................114 ADDITIONAL INFORMATION ON CONTINENTAL MOHO AND SUBDUCTED OCEANIC MOHO CONSTRAINTS ....................................................................115 FIGURES ...............................................................................117 REFERENCES ......................................................................126 SUPPLEMENTAL TABLES ................................................130 APPENDIX B: FORELAND UPLIFT DURING FLAT SUBDUCTION: INSIGHTS FROM THE PERUVIAN ANDES AND FITZCARRALD ARCH ......178 ABSTRACT ...........................................................................................179 1 Introduction .........................................................................................179 1.1 Geologic background .......................................................182 2 Proposed mechanisms for the formation of the Fitzcarrald Arch .......184 3 Methods for quantifying arch uplift ....................................................189 3.1 Gaussian approximation of rock uplift ............................189 3.2 Quantitative models of arch uplift ...................................193 4 Results .................................................................................................195 4.1 Mantle serpentinization models .......................................195 4.2 Crustal thickening models................................................197 5 Discussion ...........................................................................................199 5.1 Thickening foreland lower crust with minimal upper crustal faulting ...................................................................................199 5.2 Broader implications ........................................................202 6 Conclusions .........................................................................................207 ACKNOWLEDGEMENTS ...................................................................208 REFERENCES CITED ..........................................................................208 TABLES .................................................................................................221 6 FIGURES ...............................................................................................222 APPENDIX C: SEGMENTATION IN CONTINENTAL FOREARCS: LINKS BETWEEN LARGE SCALE OVERRIDING PLATE STRUCTURE AND SEISMOGENIC BEHAVIOR ASSOCIATED WITH THE 2010 MW 8.8 MAULE, CHILE EARTHQUAKE ...........................................232 ABSTRACT ...........................................................................................233
Load more

Recommended publications
  • Programme Monday, March 24
    23rd LAK, 2014, Heidelberg Programme 13 Programme Monday, March 24 INF 252, Hörsäle Chemie 18:00– CONFERENCE DESK OPENING 21:00 18:00– ICEBREAKER PARTY 22:00 * Sponsored by DFG travel grants 14 Programme 23rd LAK, 2014, Heidelberg Tuesday I, March 25 INF 252, Hörsaal Ost INF 252, Hörsaal West 09:30 Welcome Christina Ifrim and Wolfgang Stinnesbeck DAAD-Fördermöglichkeiten für Geowissenschaftler aus/nach Lateinamerika Sybilla Tinnap, DAAD, Bonn Talk 141: Funding Opportunities for Scientific and Technological Cooperation: The Role of the Project Management Agency European and International Cooperation International Bureau of the Bmbf Inge Lamberz de Bayas, Internationales Büro, Bundesministerium für Bildung und Forschung, Bonn International Cooperation in DFG-Programmes – Earth Sciences in Latin America Dietrich Halm, DFG, Bonn 11:00 COFFEE BREAK and POSTER SESSION Session 1: The southernmost dinosurs in Latin Session 2: Water America and their environment Chair: Heinrich Adolf Horn Chair: Marcelo Leppe 11:20 Talk 205: Late Cretaceous Terrestrial Biota from Las Talk 132: Nutrient fluxes in the groundwater affecting Chinas-Cerro Guido Complex, Magallanes Region, the northern mangrove coast of the peninsula Yucatán Southern Chile: A Key Area for the Antarctic-South (México) American Biogeography Lisa Krienen, Thomas Rüde, Eduardo Graniel Castro and Antonio Marcelo Leppe, Wolfgang Stinnesbeck, Eberhard Frey, Héctor Cardona Benavides Mansilla, Manfred Vogt, Edwin Gonzalez, Leslie Manriquez, Katherine Cisternas, Maritza Mihoc and Toshiro Jujihara
    [Show full text]
  • A Pliocene Mega-Tsunami Deposit and Associated Features in the Ranquil Formation, Southern Chile ⁎ J.P
    A Pliocene mega-tsunami deposit and associated features in the Ranquil Formation, southern Chile ⁎ J.P. Le Roux a, , Sven N. Nielsen b,1, Helga Kemnitz b, Álvaro Henriquez a a Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 13518, Correo 21, Santiago, Chile b GeoForschungsZentrum Potsdam, Section 3.1, Telegrafenberg, 14473 Potsdam, Germany Abstract An exceptionally large tsunami affected the coastline of southern Chile during the Pliocene. Its backflow eroded coarse beach and coastal dune sediments and redistributed them over the continental shelf and slope. Sandstone dykes and sills injected from the base of the resulting hyperconcentrated flow into underlying cohesive muds, assisted in plucking up large blocks of the latter and incorporating them into the flow. Locally, the rip-up intraclasts were fragmented further by smaller-scale injections to form a distinct breccia of angular to rounded mudstone clasts within a medium to coarse sandstone matrix. Sandstone sills in places mimic normal sedimentary beds, complete with structures resembling inverse gradation, planar laminae, as well as ripple and trough cross-lamination. These were probably formed by internal sediment flow and shear stress as the semi-liquefied sand was forcefully injected into cracks. In borehole cores, such sills can easily be misinterpreted as normal sedimentary beds, which can have important implications for hydrocarbon exploration. Keywords: Tsunami; Sandstone dykes; Debris flow; Mimic sedimentary structures; Eltanin impact; Hydrocarbon reservoirs 1. Introduction associated sedimentological features including large rip-up clasts and well rounded basement boulders incorporated in- The west coast of South America has a narrow shelf and to the debris, as well as sand injection from the base of the steep continental slope into a deep subduction trench.
    [Show full text]
  • Pore-Water in Marine Sediments Associated to Gas Hydrate Dissociation Offshore Lebu, Chile. Carolina Cárcamo1,2, Iván Vargas-C
    Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-362 Manuscript under review for journal Hydrol. Earth Syst. Sci. Discussion started: 29 August 2018 c Author(s) 2018. CC BY 4.0 License. 1 Pore-water in marine sediments associated to gas hydrate dissociation 2 offshore Lebu, Chile. 3 4 Carolina Cárcamo1,2, Iván Vargas-Cordero1, Francisco Fernandoy1, Umberta 5 Tinivella3, Diego López-Acevedo4, Joaquim P. Bento5, Lucía Villar-Muñoz6, Nicole 6 Foucher1, Marion San Juan1, Alessandra Rivero1 7 8 1 Universidad Andres Bello, Facultad de Ingeniería, Quillota 980, Viña del Mar, Chile 9 2 Centro de Investigación Marina Quintay. CIMARQ. Facultad de Ciencias de la Vida. Universidad 10 Andres Bello, Viña del Mar, Chile. 11 3 OGS Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Borgo Grotta Gigante 42/C, 12 34010, Sgonico, Italy. 13 4 Universidad de Concepción, Departamento de Oceanografía, Programa COPAS Sur-Austral, 14 Campus Concepción Víctor Lamas 1290, P.O. Box 160-C, Concepción, Chile 15 5 Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Av. Altamirano 1480, 16 2360007 Valparaíso, Chile. 17 6 GEOMAR Helmholtz Centre for Ocean Research, Wischhofstr. 1-3, 24148 Kiel, Germany. 18 19 ABSTRACT 20 Gas hydrate occurrences along the Chilean margin has been documented, but the 21 processes associated to fluid escapes originated by gas hydrate dissociation yet are 22 unknown. Here, we report morphologies growing related to fluid migration in the 23 continental shelf offshore western Lebu (37 °S) by analysing mainly geochemical 24 features. In this study oxygen and deuterium stable water isotopes in pore water 25 were measured.
    [Show full text]
  • Redalyc.Depositional Environment of Stelloglyphus Llicoensis Isp. Nov
    Andean Geology ISSN: 0718-7092 [email protected] Servicio Nacional de Geología y Minería Chile Le Roux, Jacobus P.; Nielsen, Sven N.; Henríquez, Álvaro Depositional environment of Stelloglyphus llicoensis isp. nov.: a new radial trace fossil from the Neogene Ranquil Formation, south-central Chile Andean Geology, vol. 35, núm. 2, julio, 2008, pp. 307-319 Servicio Nacional de Geología y Minería Santiago, Chile Disponible en: http://www.redalyc.org/articulo.oa?id=173918441006 Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto Revista Geológica de Chile 35 (2): 307-319. July, 2008 Revista Geológica de Chile www.scielo.cl/rgch.htm Depositional environment of Stelloglyphus llicoensis isp. nov.: a new radial trace fossil from the Neogene Ranquil Formation, south-central Chile jacobus P. Le Roux1, Sven N. Nielsen2, álvaro Henríquez1 1 Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 13518, Correo 21, Santiago, Chile. [email protected]; [email protected] 2 Institut für Geowissenschaften, Christian-Albrechts-Universität, Ludewig-Meyn-Str.10, 24118 Kiel, Germany. [email protected] ABSTRACT. Stelloglyphus llicoensis isp. nov. is a large radial, discoidal to ellipsoidal trace fossil with a central shaft and single to bifurcating branches radiating from different levels. A 30 m thick measured section of the Ranquil For- mation at Punta Litre contains an associated trace fossil assemblage including Zoophycos, Chondrites, Phycosiphon, Nereites missouriensis, Lockeia siliquaria, Psammichnites(?), Parataenidium, Ophiomorpha, and Rhizocorallium, some of which reworked the Stelloglyphus traces.
    [Show full text]
  • A Review of Tertiary Climate Changes in Southern South America and the Antarctic Peninsula. Part 1: Oceanic Conditions
    Sedimentary Geology 247–248 (2012) 1–20 Contents lists available at SciVerse ScienceDirect Sedimentary Geology journal homepage: www.elsevier.com/locate/sedgeo Review A review of Tertiary climate changes in southern South America and the Antarctic Peninsula. Part 1: Oceanic conditions J.P. Le Roux Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile/Centro de Excelencia en Geotérmia de los Andes, Casilla 13518, Correo 21, Santiago, Chile article info abstract Article history: Oceanic conditions around southern South America and the Antarctic Peninsula have a major influence on cli- Received 11 July 2011 mate patterns in these subcontinents. During the Tertiary, changes in ocean water temperatures and currents Received in revised form 23 December 2011 also strongly affected the continental climates and seem to have been controlled in turn by global tectonic Accepted 24 December 2011 events and sea-level changes. During periods of accelerated sea-floor spreading, an increase in the mid- Available online 3 January 2012 ocean ridge volumes and the outpouring of basaltic lavas caused a rise in sea-level and mean ocean temper- ature, accompanied by the large-scale release of CO . The precursor of the South Equatorial Current would Keywords: 2 fi Climate change have crossed the East Paci c Rise twice before reaching the coast of southern South America, thus heating Tertiary up considerably during periods of ridge activity. The absence of the Antarctic Circumpolar Current before South America the opening of the Drake Passage suggests that the current flowing north along the present western seaboard Antarctic Peninsula of southern South American could have been temperate even during periods of ridge inactivity, which might Continental drift explain the generally warm temperatures recorded in the Southeast Pacific from the early Oligocene to mid- Ocean circulation dle Miocene.
    [Show full text]
  • Dear Author, Here Are the Proofs of Your Article. • You Can Submit Your Corrections Online, Via E-Mail Or by Fax. • for On
    Dear Author, Here are the proofs of your article. • You can submit your corrections online, via e-mail or by fax. • For online submission please insert your corrections in the online correction form. Always indicate the line number to which the correction refers. • You can also insert your corrections in the proof PDF and email the annotated PDF. • For fax submission, please ensure that your corrections are clearly legible. Use a fine black pen and write the correction in the margin, not too close to the edge of the page. • Remember to note the journal title, article number, and your name when sending your response via e-mail or fax. • Check the metadata sheet to make sure that the header information, especially author names and the corresponding affiliations are correctly shown. • Check the questions that may have arisen during copy editing and insert your answers/ corrections. • Check that the text is complete and that all figures, tables and their legends are included. Also check the accuracy of special characters, equations, and electronic supplementary material if applicable. If necessary refer to the Edited manuscript. • The publication of inaccurate data such as dosages and units can have serious consequences. Please take particular care that all such details are correct. • Please do not make changes that involve only matters of style. We have generally introduced forms that follow the journal’s style. Substantial changes in content, e.g., new results, corrected values, title and authorship are not allowed without the approval of the responsible editor. In such a case, please contact the Editorial Office and return his/her consent together with the proof.
    [Show full text]
  • Andean Flat-Slab Subduction Through Time
    Andean flat-slab subduction through time VICTOR A. RAMOS & ANDRE´ S FOLGUERA* Laboratorio de Tecto´nica Andina, Universidad de Buenos Aires – CONICET *Corresponding author (e-mail: [email protected]) Abstract: The analysis of magmatic distribution, basin formation, tectonic evolution and structural styles of different segments of the Andes shows that most of the Andes have experienced a stage of flat subduction. Evidence is presented here for a wide range of regions throughout the Andes, including the three present flat-slab segments (Pampean, Peruvian, Bucaramanga), three incipient flat-slab segments (‘Carnegie’, Guan˜acos, ‘Tehuantepec’), three older and no longer active Cenozoic flat-slab segments (Altiplano, Puna, Payenia), and an inferred Palaeozoic flat- slab segment (Early Permian ‘San Rafael’). Based on the present characteristics of the Pampean flat slab, combined with the Peruvian and Bucaramanga segments, a pattern of geological processes can be attributed to slab shallowing and steepening. This pattern permits recognition of other older Cenozoic subhorizontal subduction zones throughout the Andes. Based on crustal thickness, two different settings of slab steepening are proposed. Slab steepening under thick crust leads to dela- mination, basaltic underplating, lower crustal melting, extension and widespread rhyolitic volcan- ism, as seen in the caldera formation and huge ignimbritic fields of the Altiplano and Puna segments. On the other hand, when steepening affects thin crust, extension and extensive within-plate basaltic flows reach the surface, forming large volcanic provinces, such as Payenia in the southern Andes. This last case has very limited crustal melt along the axial part of the Andean roots, which shows incipient delamination.
    [Show full text]
  • Evidence for an Early-Middle Miocene Age of the Navidad Formation (Central Chile): Paleontological, Climatic and Tectonic Implications’ of Gutiérrez Et Al
    Andean Geology 41 (3): 657-669. September, 2014 Andean Geology doi: 10.5027/andgeoV41n3-a0810.5027/andgeoV40n2-a?? formerly Revista Geológica de Chile www.andeangeology.cl REPLY TO COMMENT Reply to Comment of Encinas et al. (2014) on: ‘Evidence for an Early-Middle Miocene age of the Navidad Formation (central Chile): Paleontological, climatic and tectonic implications’ of Gutiérrez et al. (2013, Andean Geology 40 (1): 66-78) Jacobus P. Le Roux1, Néstor M. Gutiérrez1, Luis F. Hinojosa2, Viviana Pedroza1, Juan Becerra1 1 Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile-Centro de Excelencia en Geotermia de los Andes, Plaza Ercilla 803, Santiago, Chile. [email protected]; [email protected]; [email protected]; [email protected] 2 Laboratorio de Paleoecología, Facultad de Ciencias-Instituto de Ecología y Biodiversidad (IEB), Universidad de Chile, Las Palmeras 3425, Santiago, Chile. [email protected] Debate in science is always good because it forces Encinas (2006) on a specimen of Neogloboquadrina both parties to re-examine the available evidence, acostaensis, but now Encinas et al. (2014) accuse which can often be interpreted in more than one way. us of contradicting ourselves when we ‘admit that In this case, it seems as if we are at least getting a Gutiérrez et al. (2013) did not mention the Sr date, little bit closer in our interpretation of paleowater because it was too old’. We never admitted anything depths for the Navidad Formation, as Encinas et al. of the sort, as our remark referred to Encinas (2006), (2014) now ‘suspect that some of the sandstone strata not ourselves.
    [Show full text]
  • Gas Hydrate Versus Seabed Morphology Offshore Lebu
    www.nature.com/scientificreports OPEN Gas hydrate versus seabed morphology ofshore Lebu (Chilean margin) Iván Vargas‑Cordero1*, Umberta Tinivella2, Lucía Villar‑Muñoz3,4, Joaquim P. Bento5, Carolina Cárcamo6, Diego López‑Acevedo5, Francisco Fernandoy6, Alessandra Rivero6 & Marion San Juan6,7 Gas‑hydrate occurrences along the Chilean margin have been widely documented, but the processes associated with fuid escapes caused by the dissociation of gas hydrates are still unknown. We report a seabed morphology growth related to fuid migration ofshore Lebu associated with mud cones by analysing oxygen and deuterium stable water isotopes in pore water, bathymetric, biological and sedimentological data. A relief was observed at − 127 m water depth with fve peaks. Enrichment values of δ18O (0.0–1.8‰) and δD (0.0–5.6‰) evidenced past hydrate melting. The orientation of the relief could be associated with faults and fractures, which constitute pathways for fuid migration. The benthic foraminifera observed can be associated with cold seep areas. We model that the mud cones correspond to mud growing processes related to past gas‑hydrate dissociation. The integration of (i) the seismic data analysis performed in the surrounding area, (ii) the orientation of our studied relief, (iii) the infaunal foraminifera observed, (iv) the grain size and (v) the total organic matter and isotope values revealed that this area was formerly characterised by the presence of gas hydrates. Hence, this part of the Chilean margin represents a suitable area for investigating fuid‑migration processes. Along continental margins, morphological features associated with fuid escapes such as mud volcanoes, mud mounds, pockmarks, seeps, precipitates—carbonates and hydrates-, piping/rills and brine pools have been reported worldwide (e.g.1–7).
    [Show full text]
  • Geological Society of America Bulletin
    Downloaded from gsabulletin.gsapubs.org on 20 November 2009 Geological Society of America Bulletin Coastal deformation and great subduction earthquakes, Isla Santa María, Chile (37°S) Daniel Melnick, Bodo Bookhagen, Helmut P. Echtler and Manfred R. Strecker Geological Society of America Bulletin 2006;118;1463-1480 doi: 10.1130/B25865.1 Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geological Society of America Bulletin Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions
    [Show full text]
  • Depositional Setting and Early Diagenesis of the Dinosaur Eggshell-Bearing Aren Fm at Bastus, Late Campanian, South-Central Pyre
    Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees ⁎ Margarita Díaz-Molina a, , Otto Kälin b, M. Isabel Benito a, Nieves Lopez-Martinez b, Enric Vicens c a Departamento de Estratigrafía, Facultad de Ciencias Geológicas e Instituto de Geología Económica (CSIC), Universidad Complutense de Madrid, 28040 Madrid, Spain b Departamento de Paleontología, Facultad de Ciencias Geológicas e Instituto de Geología Económica (CSIC), Universidad Complutense de Madrid, 28040 Madrid, Spain c Department de Geología, Facultat de Ciènces, Universitat Autonoma de Barcelona, 08193, Bellaterra, Barcelona, Spain Received 9 June 2006; received in revised form 26 January 2007; accepted 2 February 2007 Abstract The Late Cretaceous Aren Fm exposed north of Bastus in the Tremp Basin (south-central Pyrenees) preserves an excellent record of dinosaur eggs laid in a marine littoral setting. Different from other cases reported in literature, at the Bastus site the preferential nesting ground was original beach sand. The coastal deposits of Aren Fm can be grouped into four facies assemblages, representing respectively shoreface, beachface, beach ridge plain and backbarrier lagoon environments. Shoreface deposits include fine- to coarse- grained hybrid arenites and subordinate quartz-dominated conglomerates with ripple structures of wave and wave-current origin. Beachface deposits are mainly storm beach conglomerates, but parallel-laminated foreshore arenites locally occur. Backbarrier lagoon deposits comprise of washover sandy conglomerates that grade laterally into sandy lime mudstones, biomicrites and marls. Beach ridge sediment, wherein the bulk of dinosaur eggs and eggshell debris occurs, predominantly is a reddish hybrid arenite that has undergone a complex early diagenetic evolution, including marine and meteoric cementation followed by soil development.
    [Show full text]
  • Melnick, D., Bookhagen
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, B01407, doi:10.1029/2008JB005788, 2009 Click Here for Full Article Segmentation of megathrust rupture zones from fore-arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile Daniel Melnick,1 Bodo Bookhagen,2,3 Manfred R. Strecker,1 and Helmut P. Echtler1,4 Received 8 May 2008; revised 30 September 2008; accepted 27 October 2008; published 24 January 2009. [1] This work explores the control of fore-arc structure on segmentation of megathrust earthquake ruptures using coastal geomorphic markers. The Arauco-Nahuelbuta region at the south-central Chile margin constitutes an anomalous fore-arc sector in terms of topography, geology, and exhumation, located within the overlap between the Concepcio´n and Valdivia megathrust segments. This boundary, however, is only based on 500 years of historical records. We integrate deformed marine terraces dated by cosmogenic nuclides, syntectonic sediments, published fission track data, seismic reflection profiles, and microseismicity to analyze this earthquake boundary over 102–106 years. Rapid exhumation of Nahuelbuta’s dome-like core started at 4 ± 1.2 Ma, coeval with inversion of the adjacent Arauco basin resulting in emergence of the Arauco peninsula. Here, similarities between topography, spatiotemporal trends in fission track ages, Pliocene-Pleistocene growth strata, and folded marine terraces suggest that margin-parallel shortening has dominated since Pliocene time. This shortening likely results from translation of a fore-arc sliver or microplate, decoupled from South America by an intra-arc strike-slip fault. Microplate collision against a buttress leads to localized uplift at Arauco accrued by deep-seated reverse faults, as well as incipient oroclinal bending.
    [Show full text]