DOCSLIB.ORG

Vertical-Axis Rotations Determined from Paleomagnetism of Mesozoic and Cenozoic Strata Within the Bolivian Andes David R

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Vertical-Axis Rotations Determined from Paleomagnetism of Mesozoic and Cenozoic Strata Within the Bolivian Andes David R University of Portland Pilot Scholars Environmental Studies Faculty Publications and Environmental Studies Presentations 2004 Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata within the Bolivian Andes David R. Richards Robert F. Butler University of Portland, [email protected] Thierry Sempere Follow this and additional works at: http://pilotscholars.up.edu/env_facpubs Part of the Environmental Sciences Commons, and the Geophysics and Seismology Commons Citation: Pilot Scholars Version (Modified MLA Style) Richards, David R.; Butler, Robert F.; and Sempere, Thierry, "Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata within the Bolivian Andes" (2004). Environmental Studies Faculty Publications and Presentations. 21. http://pilotscholars.up.edu/env_facpubs/21 This Journal Article is brought to you for free and open access by the Environmental Studies at Pilot Scholars. It has been accepted for inclusion in Environmental Studies Faculty Publications and Presentations by an authorized administrator of Pilot Scholars. For more information, please contact [email protected]. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, B07104, doi:l0.1029/2004JB002977, 2004 Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata of the Bolivian Andes David R. Richards 1 and Robert F. Butler Department of Geosciences, University of Arizona, Tucson, Arizona, USA Thierry Sempere3 Institut de Recherche pour le Developpement (IRD), Lima, Peru Received 16 January 2004; revised 15 April 2004; accepted 6 May 2004; published 17 July 2004. [1] Thermal demagnetization and principal component analysis allowed determination of characteristic remanent magnetization (ChRM) directions from 256 sites at 22 localities in Mesozoic and Cenozoic sedimentary strata of the Bolivian Altiplano and Eastern Cordillera. An inclination-only fold test of site-mean ChRM directions from Cenozoic units (principally the Santa Lucia Formation) indicates optimum unfolding at 97.1 % unfolding, consistent with a primary origin for the ChRM. For Mesozoic strata, optimum unfolding occurred at 89.2%, perhaps indicating secondary remagnetization at some locations. For Cenozoic units, comparison of locality-mean directions with expected paleomagnetic directions indicates vertical-axis rotations from 33° counterclockwise to 24° clockwise. Euler pole analysis of along-strike variation in crustal shortening within the Subandean and Interandean zones indicates 18° clockwise rotation south of the axis of curvature of the Bolivian Andes and 6° counterclockwise rotation northwest of the axis during the past 10 m. y. Along-strike variation of shortening within the Eastern Cordillera indicates 8° clockwise rotation south of the axis and 8° counterclockwise rotation northwest of the axis from 35 to 10 Ma. These vertical-axis rotations produced by along-strike variations in crustal shortening during development of the Bolivian fold-thrust belt agree well with observed rotations determined from paleomagnetism of Cenozoic rocks in the Eastern Cordillera and in the Subandean and Interandean zones. However, local rotations are required to account for complex rotations in the Cochabamba Basin and within the Altiplano. The curvature of the Bolivian Andes has been progressively enhanced during Cenozoic fold-thrust belt deformation. INDEX TERMS: 1525 Geomagnetism and Paleomagnetism: Paleomagnetism applied to tectonics (regional, global); 8102 Tectonophysics: Continental contractional orogenic belts; 8164 Tectonophysics: Stresses-crust and lithosphere; 9360 Information Related to Geographic Region: South America; 9604 Information Related to Geologic Time: Cenozoic; KEYWORDS: tectonics, paleomagnetism, South America, Cenozoic, Bolivia Citation: Richards, D.R., R. F. Butler, and T. Sempere (2004), Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata of the Bolivian Andes, J. Geophys. Res., 109, B07104, doi:I0.1029/2004JB002977. 1. Introduction Gephart, 1994 ]), the width of the orogen between tht Pern-Chile trench and the Subandean front reaches 850 kn [2] The Andean Cordillera has been built along an active and the crustal thickness is locally over 70 km [Beck et al. continental margin by processes directly related to the 1996; Yuan et al., 2002] (Figure 1). The second larges subduction of the oceanic Nazca plate below the South continental plateau on Earth, the Altiplano of southern Pen American continent. Along the length of the mountain chain, and Bolivia and the Puna Plateau of northern Chile anc the Andes present variations in width, <!ltitude, geology, and northwestern Argentina, is found in the Bolivian Orocline crnstal thickness. In the curved segment known as the There is broad consensus that the Bolivian Eastern Cordi!len ··Bolivian Orocline" (12°-28°S latitude; [!sacks, 1988; and Subandean belt resulted from crustal shortening, wherea~ the origin and structure of the Altiplano is debated [Bahy e1 1Now at Midland Valley Inc., Golden, Colorado. USA. al., 1997; DeCelles and Horton, 2003; McQuarrie, 2002a; 2Now at Department of Chemistry and Physics, University of Portland. Sempere et al., 2002; Husson and Sempere, 2003]. Portland, Oregon, USA. [3] Deformation within the Central Andes has included 1 Now at Laboratoire des Mecanismes et Transferts en Geologie. vertical-axis rotations on a range of scales. Syntheses oJ Universite Paul Sabatier, Toulouse, France. vertical-axis rotations documented by paleoinagnetism have Copyright 2004 by the American Geophysical Union. been presented by !sacks [1988], Beck et al. [1994], Randall 0148-0227/04.200418002977$09.00 [1998], and Somoza [1998]. Both large-scale bending ofthe B07104 1 of 21 97104 RICHARDS ET AL.: VERTICAL-AXIS ROTATIONS IN BOLIVIAN ANDES B07104 66°W Argentina Figure 1. Major geologic structures of the Altiplano, Eastern Cordillera, and Subandean and Interandean zone of Bolivia. Geologic contacts are shown in gray lines; fold axes of synclines are shown decorated with cross marks; anticlinal fold axes are undecorated and shown in heavier lines. Inset map shows central Andes with elevations > 3000 m shaded. Geologic data are from l: 1,000,000 scale Mapa Geol6gico de Bolivia geographic information databases from Servicio Nacional de Geologia y Mineria and Yacimientos Petroliferos Fiscales Bolivianos. Central Andes and ball-bearing or rotating-panel vertical­ and Somoza and Tomlinson [2002]. The number of paleo­ axis rotations of crustal blocks (10-20 km dimensions) have magnetic results from the forearc region has increased affected the forearc region of southern Peru and northern substantially during the past decade. These data clearly Chile [Beck et al., 1994; May and Butler, 1985]. Recent indicate the importance of local block rotations perhaps studies of vertical-axis rotations in these coastal regions resulting from distributed shear of the South American include Beck [1987, 1988, 1998], Randall (1998], Randall continental margin by oblique subduction [McQuarrie, et al. [2001], Rousse et al. [2002], Somoza et al. [1996, 1999] 2002a]. 2 of 21 B07104 RICHARDS ET AL.: VERTICAL-AXIS ROTATIONS IN BOLIVIAN ANDES B07Ili [4] A complete analysis of the Central Andes of Bolivia, certainty whether plunge corrections are required even llf1 northern Chile, northwest Argentina, and Peru is beyond the what appear to be straightforward structural geologic set.· scope of this paper. Instead we focus on the Bolivian Andes. tings. In presentation of paleomagnetic data and discussion The Bolivian Orocline is not an orocline in the sense of an of results below, we provide cautionary notes about vertical. originally straight mountain system that has been bent into a axis rotations determined from localities with steeply dip. curved map pattern as discussed by Carey [1955]. The ping strata. Bolivian Orocline is essentially a megasalient in the orogen [7] Paleomagnetic sampling was done using methods that displays along-strike variations in the amount of crustal described by Butler [1992]. At each paleomagnetic site shortening [Marshak, 1988]. Analysis of vertical-axis rota­ oriented samples were collected either from a single sedi~ tions in the Bolivian Orocline as the result of enhanced mentary bed or several adjacent beds with cumulative curvature of the mountain belt associated with crustal stratigraphic thickness <l m. At most sites, at least eight shortening and building of the Altiplano and Puna plateaus oriented samples (mostly cored samples) were collected at was initiated by lmcks [I 988]. Analyses of paleomagneti­ each site. Exceptions include the four localities collected cally determined vertical-axis rotations within the Bolivian during magnetostratigraphic studies (Laguna Umayo, La Andes have been presented by MacFadden et al. [1990, Palca, Sucusuma, and Tiupampa) where four oriented 1995], Butler et al. [1995], Roperch et al. [2000], and Lamb samples were collected at each site [Butler et al., 1995; [2001 a, 2001 b]. In this paper, we present paleomagnetic Sempere et al., 1997; Sige et al., 2004]. Site-mean direc­ data from Paleogene and Mesozoic sedimentary rocks at a tions from those localities were illustrated by Butler et al. large number of localities within the Altiplano and Eastern [1995] but were not tabulated in that publication; site-mean Cordillera of Bolivia. We then analyze resulting determi­ directions from Laguna Umayo have subsequently been nations of vertical-axis rotations within the Bolivian fold­ tabulated
Load more

Recommended publications
  • Sedimentology and Stratigraphy of the Upper Cretaceous-Paleocene El
    Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2002 Sedimentology and stratigraphy of the Upper Cretaceous-Paleocene El Molino Formation, Eastern Cordillera and Altiplano, Central Andes, Bolivia: implications for the tectonic development of the Central Andes Richard John Fink Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Earth Sciences Commons Recommended Citation Fink, Richard John, "Sedimentology and stratigraphy of the Upper Cretaceous-Paleocene El Molino Formation, Eastern Cordillera and Altiplano, Central Andes, Bolivia: implications for the tectonic development of the Central Andes" (2002). LSU Master's Theses. 3925. https://digitalcommons.lsu.edu/gradschool_theses/3925 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. SEDIMENTOLOGY AND STRATIGRAPHY OF THE UPPER CRETACEOUS- PALEOCENE EL MOLINO FORMATION, EASTERN CORDILLERA AND ALTIPLANO, CENTRAL ANDES, BOLIVIA: IMPLICATIONS FOR THE TECTONIC DEVELOPMENT OF THE CENTRAL ANDES A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Master of Science in The Department of Geology and Geophysics by Richard John Fink B.S., Montana State University, 1999 August 2002 ACKNOWLEDGEMENTS I would like to thank Drs. Bouma, Ellwood and Byerly for allowing me to present and defend my M.S. thesis in the absence of my original advisor.
    [Show full text]
  • Titanosaur Trackways from the Late Cretaceous El Molino Formation of Bolivia (Cal Orck’O, Sucre)
    Annales Societatis Geologorum Poloniae (2018), vol. 88: 223 – 241. doi: https://doi.org/10.14241/asgp.2018.014 TITANOSAUR TRACKWAYS FROM THE LATE CRETACEOUS EL MOLINO FORMATION OF BOLIVIA (CAL ORCK’O, SUCRE) Christian A. MEYER1, Daniel MARTY2 & Matteo BELVEDERE3 1 Department of Environmental Sciences, University of Basel, Bernoullistrasse 32, CH-4056 Basel, Switzerland; e-mail: [email protected] 2 Museum of Natural History Basel, Augustinergasse 2, CH- 4000 Basel, Switzerland; e-mail: [email protected] 3 Office de la culture, Paléontologie A16, Hôtel des Halles, P.O. Box 64, CH-2900 Porrentruy 2, Switzerland; e-mail: [email protected] Meyer, C. A., Marty, D. & Belvedere, M., 2018. Titanosaur trackways from the Late Cretaceous El Mo- lino Formation of Bolivia (Cal Orck’o, Sucre). Annales Societatis Geologorum Poloniae, 88: 223 – 241. Abstract: The Cal Orck’o tracksite is exposed in a quarry wall, approximately 4.4 km NW of Sucre (Department Chuquisaca, Bolivia) in the Altiplano/Cordillera Oriental, in the El Molino Formation (Middle Maastrichtian). Fossiliferous oolitic limestones, associated with large, freshwater stromatolites and nine levels of dinosaur tracks in the El Molino Formation document an open lacustrine environment. The main track-bearing level is almost vertical with a surface area of ~ 65,000 m2. The high-resolution mapping of the site from 1998 to 2015 revealed a total of 12,092 individual dinosaur tracks in 465 trackways. Nine different morphotypes of dinosaur tracks have been documented. Amongst them are several trackways of theropods, orni- thopods, ankylosaurs and sauropods, with the latter group accounting for 26% of the trackways.
    [Show full text]
  • Bf9ca9f92e9911b20240160c7c5
    Reu. Mus. Argentino C~enc.Nat., n.s. 6(2): 257-305,2004 Buenos A~rca,ISSN 1514-5158 Late Cretaceous vertebrates from Bajo de Santa Rosa (Alien Formation), Rio Negro province, Argentina, with the description of a new sauropod dinosaur ('ll'itanosauridae) Agustin G. MARTINELLI' & Analfa M. FORASIEPI' " 'Museu Argentino de Ciencias Naturales -Bernirrdino Rivadavia., Av A. Gallardo 470, C1405D.m Bilenos Aires, Argentina. [email protected]. zl)epartment of Anatomical Sciences and Neurobioloa, University of Louisville. I,ouisvillo, Kentucky (40292), IJSA, [email protected] ,4bstraet: A large and diverse collection of vertebrate remains from the Campanian-Maastrichtian Allen For- mation (Malargiie Group) at the Bajo de Santa Rosa locality (Rio Negro Province, Argentina) is described hore. The vertebrates arc represented hv: chondrichthvans: di~iomvstidsiluriform. le~isosteid,cf oercichthvid and titanosaurid dinosaurs. A now small salt,asaurinetit&saurid, I3onatitan reigigen. el sp. no"., is described. It is diagnosed by the following association of characters: 1) longitudinal groovo located an the suture between pari- otals that continues posteriorly over the supraoccipital to the foramen magnum; 2) basisphcnoid tubera long and narrow; 3) dorsalto middle caudal vertebrae with deep oval to circular pits present on both sides of the prespinal lamina; 4) anterior caudal vertebra with spino-postzygapophysiat and spino-prezygapophysiai lami- nae; 5) neural arch of anterior caudals with deep interzygapophysial fossae with numerous pits; 6) anterior caudal vertebra with an accessom sub-horizontal lamina extendine" from the antero-ventral oortion of the postzygapophysis to the mid-portion of tho spino-prezygapophysial lamina; and finally, 7) anterior caudal verto- bra with a prominent axial crest on the ventral surftaee of tho cerntrum.
    [Show full text]
  • Sedimentology, Palaeontology, Biostratigraphy and Correlation of the Late Cretaceous Vilquechico Group of Southern Peru
    Cretaceous Research (1993) 14, 623-661 Sedimentology, palaeontology, biostratigraphy and correlation of the Late Cretaceous Vilquechico Group of southern Peru *E. Jaillard, I'H. Cappetta, "y. Ellenberger, "Y. Feist, TN. Grambast-Fessard, $J. P. Lefranc and tB. Sigé *ORSTOM, 213 rue La Fayette, 75480 Paris Cedex 10, France, and PETROPRODUCCION, casilla 10829, Guayaquil, Ecuador, TInstitut des Sciences de 1 'Evolution, URACNRS 327, USTL, Place Eugènc Bataillon, 34095 Montpellier Cedex 5, France Kentre Géologique et Géophysique, USTL, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France P Received 9Januay 1992 and accepted 30June 1992 c Detailed analysis of the Late Cretaceous Vilquechico Group (formerly Vilquechico Formation) of the Southern Andes allows the recognition of three major sedimentary sequences, defining Lower, Middle and Upper Vilquechico lithologic formations (LVF, MVF and UVF respectively). Some of them (MVF ' and UVF) include in turn minor sedimentary sequences. In addition to dinosaur trackways, they contain .i a marine fauna (selachians, actinopterygians, molluscs) in their transgressive basal parts, and lacustrine 2 fossils (charophytes, ostracods, gastropods) in their regressive continental upper parts. Two charophyte J biozones characterize the MVF and the UVF respectively. The lithologic and sedimentary features of the 6- major sequences, as well as their palaeontological contents allow large-scale correlations with other - Andean series. Such correlations permit us to tentatively ascribe the unfossiliferous LVF to the Coniacian-early Santonian (?) time-span, and the MVF to the Santonian-late Campanian interval. The UVF is of latest Campanian-late Maastrichtian age. As a consequence, the assumed correlations between the Vilquechico Group and some of the vertebrate-bearing Andean localities are revised.
    [Show full text]
  • Redalyc.Tunasniyoj, a Dinosaur Tracksite from the Jurassic
    Anais da Academia Brasileira de Ciências ISSN: 0001-3765 [email protected] Academia Brasileira de Ciências Brasil APESTEGUÍA, SEBASTIÁN; GALLINA, PABLO A. Tunasniyoj, a dinosaur tracksite from the Jurassic-Cretaceous boundary of Bolivia Anais da Academia Brasileira de Ciências, vol. 83, núm. 1, marzo, 2011, pp. 267-277 Academia Brasileira de Ciências Rio de Janeiro, Brasil Available in: http://www.redalyc.org/articulo.oa?id=32717681013 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative “main” — 2011/2/10 — 16:06 — page 267 — #1 Anais da Academia Brasileira de Ciências (2011) 83(1): 267-277 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 www.scielo.br/aabc Tunasniyoj, a dinosaur tracksite from the Jurassic-Cretaceous boundary of Bolivia SEBASTIÁN APESTEGUÍA and PABLO A. GALLINA CONICET – Fundación de Historia Natural “Félix de Azara” CEBBAD – Universidad Maimónides, Hidalgo 775, 7◦ piso, (1405) Ciudad Autónoma de Buenos Aires, Argentina Manuscript received on October 9, 2009; accepted for publication on December 1, 2010 ABSTRACT Here we report a superbly preserved and profusely represented five-ichnotaxa dinosaur track assemblage near Icla village, 100 km southeast of Sucre, Bolivia. As preserved in reddish Jurassic-Cretaceous boundary aeolian sandstones, this rich and uncommon assemblage is, additionally, the oldest dinosaur tracksite for Bolivia. Four trackmakers were identified in the area: three quadrupedal and one bipedal, all of them with tracks of around 35 cminlenght.One of the quadrupedals is represented by no less than five adult individuals (ichnotaxon A), and four purported juveniles (ichnotaxon B) walking in association.
    [Show full text]
  • New Dinosaur Tracks from the Late Cretaceous El Molino Formation of Toro Toro (Dep
    Hallesches Jahrbuch für Geowissenschaften, Beiheft 46 (2019) 63 New dinosaur tracks from the Late Cretaceous El Molino Formation of Toro Toro (Dep. Potosi, Bolivia) CHRISTIAN A. MEYER1*, RUALDO MENEGAT2, GONZALO GARCIA³, ALONSO ALEM4 AND MARIO JALDIN5 1 Department of Environmental Sciences, University of Basel, Basel, Switzerland 2 Departamento de Paleontologia e Estratigrafia, Instituto de Geociências da UFRGS, Porto Alegre, Brasil 3 Fundación (Manuel García Capriles, MGC), La Paz, Bolivia 4 Rumi Kipu“, Comunidad Hacienda Loma, Km. 2 carretera Toro Toro - Cochabamba, Bolivia 5 El Cretácico“, Calle Guadalupe s/n, Toro Toro, Bolivia *presenting author, [email protected] Abstract: The El Molino Formation in the Toro Toro syncline (Department of Potosi, Bolivia) has long been known for it’s Cretaceous dinosaur tracks. They were briefly mentioned byB RANISA (1968). Giuseppe Leonardi led the first expedition in 1983 and mapped several surfaces. In 1984 he published the de- scription of a trackway, Ligabueichnium bolivianum attributed to an ankylosaur. In his atlas (LEONARDI 1994) five larger surfaces with tracks and trackways of theropods and sauropods are figured. Most of the sauropod trackways can be attributed to the ichnotaxon Calorckosauripus lazari MEYER, MARTY & BELVEDERE, 2018. APESTEGUÍA et al. (2011) describe purported dromaeosaurid tracks from the Toro Toro Formation, however the site is in the El Molino Formation. The latter has been deposited in a lacus- trine to fluvial environment. We report here on several new surfaces situated on the Cerro de Huayllas, the Rio T’iratani and the Quebrada Chiflon. They are situated at the base and the top of the Middle member of the El Molino Formation (Maastrichtian: see VIGNOL et al.
    [Show full text]
  • The Late Cretaceous Vertebrate Ichnofacies of Bolivia - Facts and Implications
    Asociación Paleontológica Argentina. Publicación Especial 7 ISSN 0328-347X VII International Symposium on Mesozoic Terrestrial Ecosystems: 133-138.Buenos Aires, 30-6-2001 The Late CretaceOUS vertebrate ichnofacieS of Bolivia - facTS aNd implications 1 2 CA. MEYER , D. HIPPLER and M.G. LOCKLEy3 Abstract. Cretaceous dinosaur tracks are known in Central Bolivia since 1968. Recent work shows that tracksites are widespread and occur in multiple layers from the Campanian to the Late Maastrichtian. The ichnofauna is associated with alluvial to deltaic as well as lacustrine settings. Several new sites with tracks of titanosaurids and theropods in the upper part of the Chaunaca Formation (Campanian) correspond to similar stratigraphic levels in the Toro-Toro Formation further north. The Late Maastrichtian deposits yield a megatracksite that spreads from southern Peru (Vilquechico Formation) to the Central Bolivian Andes (El Molino Formation) down to the Salta province in northern Argentina (YacoraiteFormation). The ichnofauna of the El Molino Formation has been studied at the Cal Orcko locality, close to Sucre (Bolivia). The main trackbearing surface is a lacustrine limestone (25,000m') which is steeply inclined (70°);it has been mapped with heavy climbing equipment in 1998.The trackbearing levels show episodic pedogene- sis, stromatolites and tempestites and were deposited in ephemeral and perenniallakes. 313 trackways on nine levels have been registered. Five different types of dinosaurs are present. Among those are medium- sized titanosaurs, small to intermedia te sized theropods and few ornithopods. For the first time, tracks of ankylosaurs on the South American continent can be demonstrated. The high diversity of the track as- semblage clearly demonstrates that there was no gradual decline in dinosaur diversity towards the end of the Cretaceous and favours a drastic event at the KIT boundary.
    [Show full text]
  • N4iaieuican%Mlsdllm
    n4iaieuican%Mlsdllm PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK 24, N.Y. NUMBER 2159 NOVEMBER 8,I963 Cretaceous Fishes from Bolivia, with Comments on Pristid Evolution BY BOBB SCHAEFFER' In connection with a current investigation of the Mesozoic rock sequence in central Bolivia, Dr. Aniello Russo of the Yacimientos Petro- liferos Fiscales Bolivianos collected vertebrate remains at various locali- ties in a unit recently designated as the El Molino Formation. These remains, which include several kinds of fishes and a turtle, were sent to me for identification and possible age determination by Prof. Leonardo Branisa of the Departamento Nacional de Geologia. I am indebted to Professor Branisa for presenting this collection to the American Museum and for furnishing data on the stratigraphic occur- rence. Dr. H. J. Harrington of the Tennessee Overseas Company has generously provided a critical summary of the pertinent stratigraphy. Mr. Charles C. Smith of Houston, Texas, and Dr. Nicholas Hotton of the United States National Museum, Smithsonian Institution, have kindly lent specimens of Onchopristis dunklei, and Drs. C. L. McNulty, Jr., and B. H. Slaughter have permitted me to examine their manuscript on this species. Dr. Ricbard Estes has furnished information on the Rhom- bodus-Myledaphus complex. Dr. J. A. F. Garrick and Dr. D. H. Davies have supplied helpful data on the habits and distribution of the sawfish and sawshark. Dr. M. L. Moss has aided in the interpretation of pristid rostral tooth histology. The drawings were made by Mr. Michael Insinna, and the photographs were taken by Mr.
    [Show full text]
  • The Development of the Bauru Basin in the Back-Bulge Province
    Marine and Petroleum Geology 73 (2016) 131e156 Contents lists available at ScienceDirect Marine and Petroleum Geology journal homepage: www.elsevier.com/locate/marpetgeo Research paper The South American retroarc foreland system: The development of the Bauru Basin in the back-bulge province * Mirian Costa Menegazzo a, , Octavian Catuneanu b, Hung Kiang Chang c a Universidade Petrobras, Petroleo Brasileiro S.A. e Petrobras, rua Júlio do Carmo, 323, Rio de Janeiro, Rio de Janeiro, 20211-160, Brazil b Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Edmonton, Alberta, T6G 2E3, Canada c Laboratorio de Estudos de Bacias, Universidade Estadual Paulista, Avenida 24-A, 1515, Rio Claro, Sao~ Paulo, 13506-900, Brazil article info abstract Article history: The aim of this research is to understand the tectonic setting of the Bauru Basin. This basin in central- Received 16 October 2015 eastern South America has been classified as intracratonic, but the basin-fill geometry, the involved Received in revised form subsidence mechanisms and the age of the deposits are poorly understood. In this work, the ranges of 21 February 2016 the fossil taxa are analyzed and ages are proposed for the lithostratigraphic units. Isopach maps were Accepted 23 February 2016 used to reconstruct the stratigraphic intervals of the basin fill. The stratigraphy of the Bauru Basin is Available online 27 February 2016 compared with that of the adjacent basins, and the data are integrated with the available information on South American geodynamics. The fossil record indicates that sediment accumulated from the Cen- Keywords: fi Andean orogeny omanian to early Paleocene, beginning after the Mochica Phase of the Andean orogeny.
    [Show full text]
  • GSA Bulletin: Stratigraphy and Chronology of Upper Cretaceous
    Stratigraphy and chronology of Upper Cretaceous–lower Paleogene strata in Bolivia and northwest Argentina T. Sempere Département T.O.A., Orstom, 213 rue Lafayette, 75010 Paris, France R. F. Butler* Department of Geosciences, University of Arizona, Tucson, Arizona 85721 D. R. Richards } L. G. Marshall Institute of Human Origins, 1288 9th Street, Berkeley, California 94710 W. Sharp Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709 C. C. Swisher III } ABSTRACT INTRODUCTION Integration of sequence stratigraphy, magnetostratigraphy, Ar/Ar The Andean basin of South America was an underfilled foreland basin of dating, and paleontology considerably advances knowledge of the Late the early Andes in the Late Cretaceous and Paleogene. Periodic marine con- Cretaceous–early Paleogene chronostratigraphy and tectonic evolution nections with the Caribbean region occurred in the Maastrichtian–Danian of Bolivia and adjacent areas. The partly restricted marine El Molino (Fig. 1). Due to considerable eastward propagation of deformation since the Formation spans the Maastrichtian and Danian (~73–60.0 Ma). Depo- late Oligocene, Bolivia has excellent exposures of Cretaceous and Cenozoic sition of the alluvial to lacustrine Santa Lucía Formation occurred be- strata, including rocks suitable for paleomagnetic studies and Ar/Ar dating. tween 60.0 and 58.2 Ma. The widespread erosional unconformity at the We summarize and update the Late Cretaceous–early Paleogene stratig- base of the Cayara Formation is 58.2 Ma. This unconformity separates raphy of Bolivia and adjacent areas. In particular we provide a detailed the Upper Puca and Corocoro supersequences in Bolivia, and is thus chronostratigraphy of the Maastrichtian and Paleocene strata of the central coeval with the Zuni-Tejas sequence boundary of North America.
    [Show full text]
  • The Mesozoic and Paleocene Vertebrates of Bolivia and Their Stratigraphic Context : a Review
    TIIE MESOZQIC AND PALEOCENE VERTEBRATES OF BOLIVIA AND THEIR STB2ATIGRAPHIC CONTEXT : A REVIEJN MIREILLE GAYET", LARRY G. MARSHALL** & THIERRY SEMPERE*** *URA 11 du CNRS, Centre des Sciences de la Terre, Lyon I,2743 boulevard du 11 novernbre. 69622 Villeurbanne, Fraice ** Itistitute of IIunian Origins, 2453 Ridge Road, Berkeley, California 94709, USA ***Convenio YPFB-Orstom (UR IH), Sanh Cruz de la Sierra, Bolivia. Present addiess: Centre de GCologie GCnérale et Minière, Ecole des Mines, 35 rue Saint-HonorC,77305 Fontninebleau, France ~ INTRODUCTION Brazil, eastern Paraguay, northern Uruguay aiid northeastern Argentinn. In contrast, the latest Jurcissic-I'nlcocenc clcpositioiial arca Dolivia lias a rich nnd diverse record of fossil verkbratcs for the was mainly restricted to tile Andean doniairi aiid bcloiigctl to thc al., Mcso7.oic aiid early Ceno7,oic. The majority of he 56 knowii fossil back-atc basin of the Pacific margin (Sctnpcre et 1988), localities for this time interval occur in the soutlierri Altiplano and in although soine late Cretaceous-Paleocene uiiits are also known in thc soutlicrii piut d the Cordillera 01ieiitnl (Figs. 1-4). parts of the iioitlicrn and cciifrril Suhnndcnii bclt (Figs. 1, 2). In Illis pnpcr we review thc iniddlc Triassic llirougli 1)nlcocciic The "Coiido cvcnt" thnt scpnriilcs tlicsc two intcrvnls ciiii be fossil vertebrote record of Bolivia in its strntigrnphic and iiiterpretcd as tlic capturc of tlic Bolivian Andean doinaiil, which palcociiviroririicntal context aiid attempt to correlate tliese rocks aid until Uien liad belonged to die crotoriic area, by tlie Pacific back-wc. faunas with those in, adjaccrit Argeiitina, Brazil, Chile arid Pcru.
    [Show full text]
  • Titanosaur Trackways from the Late Cretaceous El Molino Formation of Bolivia (Cal Orck’O, Sucre)
    Annales Societatis Geologorum Poloniae (2018), vol. 88: 223 – 241. doi: https://doi.org/10.14241/asgp.2018.018 TITANOSAUR TRACKWAYS FROM THE LATE CRETACEOUS EL MOLINO FORMATION OF BOLIVIA (CAL ORCK’O, SUCRE) Christian A. MEYER1, Daniel MARTY2 & Matteo BELVEDERE3 1 Department of Environmental Sciences, University of Basel, Bernoullistrasse 32, CH-4056 Basel, Switzerland; e-mail: [email protected] 2 Museum of Natural History Basel, Augustinergasse 2, CH- 4000 Basel, Switzerland; e-mail: [email protected] 3 Office de la culture, Paléontologie A16, Hôtel des Halles, P.O. Box 64, CH-2900 Porrentruy 2, Switzerland; e-mail: [email protected] Meyer, C. A., Marty, D. & Belvedere, M., 2018. Titanosaur trackways from the Late Cretaceous El Mo- lino Formation of Bolivia (Cal Orck’o, Sucre). Annales Societatis Geologorum Poloniae, 88: 223 – 241. Abstract: The Cal Orck’o tracksite is exposed in a quarry wall, approximately 4.4 km NW of Sucre (Department Chuquisaca, Bolivia) in the Altiplano/Cordillera Oriental, in the El Molino Formation (Middle Maastrichtian). Fossiliferous oolitic limestones, associated with large, freshwater stromatolites and nine levels of dinosaur tracks in the El Molino Formation document an open lacustrine environment. The main track-bearing level is almost vertical with a surface area of ~ 65,000 m2. The high-resolution mapping of the site from 1998 to 2015 revealed a total of 12,092 individual dinosaur tracks in 465 trackways. Nine different morphotypes of dinosaur tracks have been documented. Amongst them are several trackways of theropods, orni- thopods, ankylosaurs and sauropods, with the latter group accounting for 26% of the trackways.
    [Show full text]