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Rodinia to Gondwana: the Geodynamic Map of Gondwana Supercontinent Assembly

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Vol. 7, No. 1 January 1997 INSIDE • Presidential Address, p. 7 GSA TODAY • Southeastern Section Meeting, p. 22 A Publication of the Geological Society of America • Annual Meeting Recap, p. 36 Rodinia to Gondwana: The Geodynamic Map of Gondwana Supercontinent Assembly Raphael Unrug Department of Geological Sciences, Wright State University, Dayton, OH 45435 ABSTRACT The new Geodynamic Map of Gond- wana Supercontinent Assembly provides insight into the Neoproterozoic breakup of the Rodinia supercontinent that existed from 1000 to 725 Ma, and the subsequent amalgamation of Gond- wanaland. Breakout of Laurentia from Rodinia at 725 Ma marks the reorganiza- tion of lithospheric plate motions that resulted in the Pan African–Brasiliano orogeny and assembly of Gondwana- land that lasted from 725 to 500 Ma. INTRODUCTION The Geodynamic Map of Gondwana Supercontinent Assembly1 at a scale of 1:10 million was first presented at the 30th International Geological Congress, in Beijing, in August 1996. The map is a Figure 1. Reconstruction of Gondwanaland after 500 Ma and index map for Neoproterozoic mobile joint endeavor of International Geological belts of Gondwanaland. Mobile belts include collisional and transpressional orogens and aulacogens. Correlation Program Project 288 “Gond- Aulacogens are aborted rifts, undeformed to mildly deformed, terminating inside cratons. Gray = Archean- wanaland Sutures and Fold Belts” (data- Paleoproterozoic cratons (pre–1600 Ma); green = Mesoproterozoic (1600–100 Ma) mobile belts; Neo- base generation), the Council for Geo- proterozoic (1000–440 Ma) orogens in red, and aulacogens in white with red stipple; geodynamic provinces peripheral to Gondwanaland in shades of blue. Mobile belt index: 1—Mauretanides, 2— science, Pretoria, South Africa (Geographic Bassarides, 3—Rokelides, 4—Anti-Atlas, 5—Ougarta aulacogen, 6—Trans-Saharan, 7—Tibesti, 8—Gourma Information Systems [GIS] and digital car- aulacogen, 9—Dahomeides, 10—Nigeria-Cameroon, 11—Borborema, 12—Sergipe-Oubanguide, 13— tography), and the Bureau de Recherches East African, 14—Araguaia, 15—Goias, 16—Brasilia, 17—Paramirim aulacogen, 18—Araçuai, 19—West Géologiques et Minières, Orléans, France Congo, 20—Sangha aulacogen, 21—Tucavaca aulacogen, 22—Paraguay-Cordoba, 23—Pampean Ranges, (printing). It contains original contribu- 23a—Northern Patagonia, 24—Ribeira, 25—Rio Doce, 26—Dom Feliciano, 27—Kaoko, 28—Damara, 29— Lufilian, 30—Kundelungu aulacogen, 30a—Bukoban aulacogen, 31—Zambezi, 32—Gariep, 33—Saldania, tions by 67 coauthors from 11 countries. 34—Beardmore, 35—Pinjarra, 36—Adelaide, 37—Paterson-Peterman Ranges. GIS and digital cartography were managed by L. G. Wolmarans (CGS). The Editorial Committee included: C. Castaing (BRGM), J. L. Feybesse (BRGM), P. G. Gresse (CGS), tion of the mobile belts that suture the belts across modern oceans provided a C. McA. Powell (UWA), G. R. Sadowski cratons within Gondwanaland. means for reconstruction of superconti- (USP), L. Tack (MRAC), and R. Unrug nent assembly by geodynamic interpreta- (WSU) (see p. 5). GEODYNAMIC MAP SETUP AND tion of depositional, igneous, tectonic, Here I present the basis for construct- PHILOSOPHY and metamorphic events. Recognition of ing the geodynamic map from which the The objective of the Geodynamic Map the role played by Laurentia in the assem- index and summary maps, Figures 1–3, of Gondwana Supercontinent Assembly is to bly and breakup of Rodinia—the precursor were derived, and the synoptic insights present a synthesis of the accretion of supercontinent to Gondwanaland—and gleaned from the cartographic visualiza- Gondwanaland, which is composed of the application of lithotectonic terrane lithospheric plates that traveled large dis- concepts to the better studied Neoprotero- tances during the Neoproterozoic (1000 to zoic mobile belts added complexity to the 1R. Unrug, editor, 1996, scale 1:10 million, 545 Ma). Latitudinal movements of the geodynamic interpretation. four sheets, total dimensions 1,950 x 1,250 mm, 19 colors; published by Bureau de Recherches cratons that resided within Gondwana Chronostratigraphic limits for subdi- Géologiques et Minières, US$50. Order from: were determined from paleomagnetic vision of the Proterozoic period into Meso- Editions BRGM, Ave. Claude Guillemin, BP 6009, data, and their relative movements were proterozoic (1600 to 1000 Ma) and Neo- F-45060 Orléans Cedex 2, France, fax 33-2-38-64- inferred from events registered in mobile proterozoic (1000 Ma to the start of the 36-82, or Director, Council for Geoscience, Private Bag X112, Pretoria 0001, South Africa, Attn.: Infor- belts in the reconstituted supercontinent. mation Division, fax 27-12-841-1221. Intercontinental correlations of mobile Map continued on p. 2 IN THIS ISSUE January GSA TODAY Rodinia to Gondwana: GSA Bulletin Update .................... 20 Vol. 7, No. 1 1997 The Geodynamic Map of Gondwana GSA On The Web ...................... 21 Supercontinent Assembly ............ 1 GSA TODAY (ISSN 1052-5173) is published Award Nomination Summary ........... 21 monthly by The Geological Society of America, Inc., Research Grant Alternates .............. 6 Southeastern Section Meeting .......... 22 with offices at 3300 Penrose Place, Boulder, Colorado. Why the Journals Are Late .............. 6 Mailing address: P.O. Box 9140, Boulder, CO 80301- Bulletin and Geology Contents ........... 28 9140, U.S.A. Periodicals postage paid at Boulder, Col- 1996 Presidential Address .............. 7 Congressional Science Fellowship ....... 29 orado, and at additional mailing offices. Postmaster: GSAF Update .......................... 12 Send address changes to GSA Today, Membership Ser- In Memoriam .......................... 29 vices, P.O. Box 9140, Boulder, CO 80301-9140. Officers and Councilors for 1997 ........ 14 Calendar .............................. 30 Copyright © 1997, The Geological Society of America, Washington Report .................... 15 GSA Meetings ......................... 31 Inc. (GSA). All rights reserved. Copyright not claimed on Congressional Science Fellow Report: content prepared wholly by U.S. Government employees The Bucks Start Here ................... 16 1997 GeoVentures ..................... 32 within the scope of their employment. Permission is granted to individuals to photocopy freely all items other Division Officers for 1997 ............... 17 1996 Annual Meeting .................. 36 than the science articles to further science and educa- Environment Matters ................... 18 Classifieds ............................. 38 tion. Individual scientists are hereby granted permission, without royalties or further requests, to make unlimited Wanted: Mentors in Applied Geology . 18 New Geology Co-Editor ................. 40 photocopies of the science articles for use in classrooms to further education and science, and to make up to five copies for distribution to associates in the furtherance of science; permission is granted to make more than five photocopies for other noncommercial, nonprofit pur- Map continued from p. 1 and anorogenic magmatic suites. Symbols poses furthering science and education upon payment for metamorphic rock units show foliation of the appropriate fee ($0.25 per page) directly to the Copyright Clearance Center, 27 Congress Street, Salem, Cambrian) periods follow the time scale trends, nature of protoliths, and metamor- Massachusetts 01970, phone (508) 744-3350 (when approved by the International Union of phic facies. Structural symbols indicate paying, reference GSA Today, ISSN 1052-5173). Written Geological Sciences (IUGS). The beginning plate margins, faults, structural trends of permission is required from GSA for all other forms of capture, reproduction, and/or distribution of any item in of the Cambrian Period is taken as ~545 folds and foliation, and tectonic transport this publication by any means. GSA provides this and Ma for correlation of chronometric and directions. other forums for the presentation of diverse opinions geologic time scales (Plumb, 1990; and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Brasier et al., 1994). GONDWANALAND QUESTIONS Opinions presented in this publication do not reflect offi- Archean to Paleoproterozoic (pre– Neoproterozoic organization of conti- cial positions of the Society. 1600 Ma) cratons that rode the moving nental crust into large supercontinents is lithospheric plates, but underwent no the subject of ongoing debate, and various SUBSCRIPTIONS for 1997 calendar year: Society Members: GSA Today is provided as part of member- deformation during Mesoproterozoic, models are evolving as new data become ship dues. Contact Membership Services at (800) 472- Neoproterozoic, and Paleozoic orogenies available (Powell, 1993; Dalziel, 1991; 1988 or (303) 447-2020 for membership information. are considered passive elements of the Trompette, 1994; Stern, 1994; Rogers et al., Nonmembers & Institutions: Free with paid sub- scription to both GSA Bulletin and Geology, otherwise Gondwanaland jigsaw puzzle. No struc- 1995b; Unrug, 1995; Yoshida, 1995). The $50 for U.S., Canada, and Mexico; $60 elsewhere. tural details are shown in these cratons, main questions are: Were there one or Contact Subscription Services. Single copies may be except for Mesoproterozoic and Neopro- more Neoproterozoic supercontinents, requested from Publication Sales. Also available on an annual CD-ROM, (with GSA Bulletin, Geology, GSA Data terozoic cover units, intracratonic
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  • The Making and Unmaking of a Supercontinent: Rodinia Revisited

    The Making and Unmaking of a Supercontinent: Rodinia Revisited

    Tectonophysics 375 (2003) 261–288 www.elsevier.com/locate/tecto The making and unmaking of a supercontinent: Rodinia revisited Joseph G. Meerta,*, Trond H. Torsvikb a Department of Geological Sciences, University of Florida, 241 Williamson Hall, PO Box 11210 Gainesville, FL 32611, USA b Academy of Sciences (VISTA), c/o Geodynamics Center, Geological Survey of Norway, Leif Eirikssons vei 39, Trondheim 7491, Norway Received 11 April 2002; received in revised form 7 January 2003; accepted 5 June 2003 Abstract During the Neoproterozoic, a supercontinent commonly referred to as Rodinia, supposedly formed at ca. 1100 Ma and broke apart at around 800–700 Ma. However, continental fits (e.g., Laurentia vs. Australia–Antarctica, Greater India vs. Australia– Antarctica, Amazonian craton [AC] vs. Laurentia, etc.) and the timing of break-up as postulated in a number of influential papers in the early–mid-1990s are at odds with palaeomagnetic data. The new data necessitate an entirely different fit of East Gondwana elements and western Gondwana and call into question the validity of SWEAT, AUSWUS models and other variants. At the same time, the geologic record indicates that Neoproterozoic and early Paleozoic rift margins surrounded Laurentia, while similar-aged collisional belts dissected Gondwana. Collectively, these geologic observations indicate the breakup of one supercontinent followed rapidly by the assembly of another smaller supercontinent (Gondwana). At issue, and what we outline in this paper, is the difficulty in determining the exact geometry of the earlier supercontinent. We discuss the various models that have been proposed and highlight key areas of contention. These include the relationships between the various ‘external’ Rodinian cratons to Laurentia (e.g., Baltica, Siberia and Amazonia), the notion of true polar wander (TPW), the lack of reliable paleomagnetic data and the enigmatic interpretations of the geologic data.