DOCSLIB.ORG

RESEARCH Geochronology and Geochemistry Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
RESEARCH Geochronology and Geochemistry Of RESEARCH Geochronology and geochemistry of Neoproterozoic granitoids in the central Qilian Shan of northern Tibet: Reconstructing the amalgamation processes and tectonic history of Asia Chen Wu1,*, Andrew V. Zuza2,3, An Yin1,2, Changfeng Liu4, Robin C. Reith2, Jinyu Zhang5, Wencan Liu4, and Zhiguang Zhou1 1STRUCTURAL GEOLOGY GROUP, CHINA UNIVERSITY OF GEOSCIENCES (BEIJING), BEIJING 100083, CHINA 2DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES, UNIVERSITY OF CALIFORNIA, LOS ANGELES, CALIFORNIA 90095-1567, USA 3NEVADA BUREAU OF MINES AND GEOLOGY, UNIVERSITY OF NEVADA, RENO, NEVADA 89557, USA 4INSTITUTE OF GEOLOGICAL SURVEY, CHINA UNIVERSITY OF GEOSCIENCES (BEIJING), BEIJING 100083, CHINA 5INSTITUTE OF GEOLOGY, CHINA EARTHQUAKE ADMINISTRATION, BEIJING 100029, CHINA ABSTRACT Our understanding of the assembly history of Asia depends critically on the tectonic relationships between its major cratons, including Siberia, North China, South China, and Tarim. The intervening microcontinents between these cratons can provide insight into the paleogeographic and paleotectonic relationships of the cratons, but there is currently a general lack of knowledge regarding the basement geology of these microcontinents. Here we present results from systematic geologic mapping, U-Pb zircon dating, whole-rock geochemical analysis, and syn- thesis of existing data to establish the Proterozoic to early Paleozoic evolution of the central Qilian basement to the south of the North China craton in northwest China. Our results indicate that the region underwent three major periods of magmatic activity at 960–880, 877–710, and 550–375 Ma. Our geochemical analysis suggests that the ca. 900 Ma plutons were generated during arc magmatism and/or syncollisional crustal melting, whereas the ca. 820 Ma plutons are A-type granitoids, which are typically associated with extensional tectonism. Igneous zircons from a high- and ultrahigh-pressure eclogite in the north-central Qilian Shan have a U-Pb age of ca. 916 Ma, whereas dating of the recrystallized rims suggests that eclogite facies metamorphism occurred at ca. 485 Ma. Our detrital zircon geochronology also indicates that a widespread metasedimentary unit in the region was deposited between ca. 1200 and ca. 960 Ma, prior to the onset of a rift-drift event at ca. 750 Ma. Based on regional geologic constraints and the magmatic history, we propose the following tectonic history: (1) the paleo–Qilian Ocean bound the combined North Tarim–North China craton to the south (present-day coordinates) in the Mesoproterozoic; (2) the paleo– Qilian Ocean closed between 900 and 820 Ma following the collision of North Tarim–North China craton and the South Tarim–Qaidam–Kunlun continent; (3) the younger Qilian Ocean opened at ca. 775 Ma along the previous suture trace of the paleo–Qilian Ocean as a marginal sea within southern Laurasia; and (4) this ocean closed by ca. 445–440 Ma as a result of collision between the Tarim–North China cratons and the Qaidam-Kunlun continent along a south-dipping subduction system. LITHOSPHERE; v. 9; no. 4; p. 609–636; GSA Data Repository Item 2017231 | Published online 25 May 2017 https://doi.org/10.1130/L640.1 INTRODUCTION 2000; Chen et al., 2003; Cowgill et al., 2003; Yin, 2010; Gao et al., 2013; Zuza and Yin, 2016; Zuza et al., 2016). Northern Tibet marks the transitional zone between the Tethyan oro- Early workers suggested that the ophiolite-bearing mélange and blue- genic system to the south and the Paleo–Asian Ocean system to the north schist assemblages exposed across the Qilian Shan represented an early (Fig. 1) (e.g., Şengör and Natal’in, 1996; Yin and Harrison, 2000; Heubeck, Paleozoic Qilian Ocean (Wang and Liu, 1976; Xiao et al., 1978). Later 2001; Stampfli and Borel, 2002; Stampfli et al., 2013; Wu et al., 2016). studies revealed that the Qilian Ocean may have formed as early as the Although extensive research has focused on the tectonic evolution of these Neoproterozoic (e.g., Yin and Harrison, 2000; Gehrels et al., 2003a, 2003b, two well-known orogenic domains, comparatively little research has been 2011; Yin et al., 2007a; Xiao et al., 2009; Song et al., 2013, 2014; Xu et al., devoted to investigating the tectonic history of intervening oceanic and 2015; Wu et al., 2016). However, the lack of absolute age constraints and continental fragments, including the early Paleozoic Qilian orogen (e.g., an unclear geologic context of the Neoproterozoic strata have hampered Yin et al., 2007a; Xiao et al., 2009; Song et al., 2013). A major challenge our ability to decipher the origin and formation ages of this ocean. This in unraveling the geologic history of the Qilian orogen is that the region has in turn led to debates regarding (1) the location and lateral extent of was strongly modified by later phases of Mesozoic extension and Cenozoic the Qilian Ocean as represented by the suture zone rocks (e.g., Tseng et al., intracontinental thrust and strike-slip faulting (Fig. 1) (Yin and Harrison, 2009), (2) the polarity of subduction that led to the closure of the Qilian Ocean (e.g., Zuo and Liu, 1987; Feng and He, 1996; Yin and Harrison, *Corresponding author: [email protected]; [email protected] 2000; Yang et al., 2002; C.L. Wu et al., 2006; Gehrels et al., 2003a, 2003b, LITHOSPHERE© 2017 Geological | Volume Society 9 of| America.Number 4For | www.gsapubs.orgpermission to copy, contact [email protected] 609 Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/9/4/609/2316115/609.pdf by guest on 27 September 2021 CHEN WU ET AL. A Central Asian Orogenic System 0250 500 km Closure sites of Proto-Tethys ATR SQS Fig. 1B NQS Karakum Tarim ATF North China KQD CQLT QKT KQD SQS KQD NQGS JS CQGS SGT KF BN QTT SQGS LST Closure site of IT Neo-Tethys South China India Closure sites of Paleo-Tethys Ordovician intra-plate UHP terranes Western KF Karakorum fault Closure site of Pacific ATF Altyn Tagh fault Meso-Tethys Subduction ARSZ Ailao Shan-Red River shear zone ARSZ System KQD: Kunlun-Qinling-Dabie suture; NQS and SQS: North and South Qilian sutures; NQGS, CQGS, and SQGS: North, Central, and South Qinling suture; JS: Jinsha suture; BN: Bangong-Nujiang suture; IT: Indus-Tsangpo suture. QKT: Qaidam-Kunlun terrane; SGT: Songpan-Ganzi terrane; QTT: Qiangtang terrane; LST: Lhasa terrane; CQLT: central Qilian terrane; KF: Karakorum fault; ARSZ: Ailao Shan-Red River shear zone; ATF: Altyn Tagh fault; ATR: Altyn Tagh Range. Altyn Tagh B Altyn Tagh Qilian Shan-Nan Shan Range Fault Thrust Belt N 40° E study area Figure 2A Fig.2 North Har Lake China Ordos 38° E Block Qaidam Qinghai Xining Lake LiupanShan Basin Thrust Belt Kunlun 36° E Fault BoundariesHaiyuan of Te thyan OrogenicFa Systemult 200 km 34° E 94° E 96° E 98° E 100° E 102° E 104° E 106° E 108° E Figure 1. (A) Tectonic map of the Tethyan Orogenic System and the Central Asian Orogenic System (modified from Wu et al., 2016). (B) Regional tectonic map of the Qilian Shan–Nan Shan thrust belt and its adjacent regions (modified from Gao et al., 2013; Zuza et al., 2016). Major faults are denoted with black lines (thrust), blue lines (sinistral strike slip), yellow lines (dextral strike slip), and pink lines (normal). Underlying base map is from www.geomapapp.org (Ryan et al., 2009). 610 www.gsapubs.org | Volume 9 | Number 4 | LITHOSPHERE Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/9/4/609/2316115/609.pdf by guest on 27 September 2021 Proterozoic to early Paleozoic evolution of northern Tibet | RESEARCH 2011; Tung et al., 2007, 2013; Song et al., 2006, 2010, 2013, 2014; Huang Ga and locally reworked at 250–230 Ma (Yu et al., 2009). Mesoprotero- et al., 2015; Xu et al., 2015), and (3) the lateral linkage of the Precambrian zoic basement rocks (1431–1200 Ma) are restricted to Hainan Island (Li Qilian basement (Qaidam-Kunlun terrane), which is bounded by the north et al., 2002; X.H. Li et al., 2008a). A compilation of U-Pb zircon ages and south Qilian suture zones to the north and the Kunlun-Qinling-Dabie shows that >90% of the Cathaysia block Precambrian basement consists suture to the south (Fig. 1A), with either the North China or South China of Neoproterozoic rocks, including volcanic-sedimentary strata metamor- cratons (e.g., Zuo and Liu, 1987; Feng and He, 1996; Wan et al., 2001; phosed from greenschist to granulite facies (Zhao and Cawood, 2012). The Tung et al., 2007, 2013; Lu et al., 2008; Song et al., 2010, 2012, 2013; Cathaysia block underwent a widespread tectonothermal event in the early Xu et al., 2015; Wu et al., 2016) (Fig. 1). A Qilian–South China craton Paleozoic, resulting in an angular unconformity between Devonian cover connection would require that the Qilian continental basement (Qaidam- and metamorphosed pre-Silurian strata (Huang, 1977; Wang et al., 2013b). Kunlun terrane) was first rifted from the Yangtze craton in the western In the recent reconstruction (Wu et al., 2016), the Yangtze basement is part of the South China craton during the Neoproterozoic breakup of the assumed to extend west underneath the Songpan-Ganzi terrane (see dis- supercontinent Rodinia and later collided against the North China craton cussion in Zhang et al., 2014) and this entire craton rifted from Gondwana in the early Paleozoic (e.g., Wan et al., 2001; Tung et al., 2007; Song et in the Devonian–Carboniferous (e.g., Zhao and Cawood, 2012; Cawood et al., 2013; Xu et al., 2015). In contrast, a Qilian–North China connection al., 2013). The craton was bound to the north by the Neo–Kunlun Ocean requires that the Qaidam-Kunlun terrane never drifted far from the North (Mianlue Ocean) (e.g., Ratschbacher et al., 2003; Dong and Santosh, 2015) China craton since the Neoproterozoic.
Load more

Recommended publications
  • Community Involvement in Geoconservation: a Conceptual Approach Based on the Geoheritage of South Angola
    Sustainability 2015, 7, 4893-4918; doi:10.3390/su7054893 OPEN ACCESS sustainability ISSN 2071-1050 www.mdpi.com/journal/sustainability Article Community Involvement in Geoconservation: A Conceptual Approach Based on the Geoheritage of South Angola Alexandre Oliveira Tavares 1,2,*, Maria Helena Henriques 2,3,†, Artur Domingos 4,† and Abel Bala 5,† 1 Centre for Social Studies, University of Coimbra (Polo II), Rua Sílvio Lima, 3030-790 Coimbra, Portugal 2 Department of Earth Sciences, University of Coimbra (Polo II), Rua Sílvio Lima, 3030-790 Coimbra, Portugal 3 Geosciences Centre, University of Coimbra (Polo II), Rua Sílvio Lima, 3030-790 Coimbra, Portugal; E-Mail: [email protected] 4 Magistério Primário do Lubango-Nambambe, Lubango, Angola; E-Mail: [email protected] 5 Instituto Superior Politécnico da Tundavala and Escola Secundária do 2° Ciclo/Quilengues, Huíla, Angola; E-Mail: [email protected] † These authors contributed equally to this work. * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +351-239-860-566; Fax: +351-239-860-501. Academic Editor: Marc A. Rosen Received: 24 March 2015 / Accepted: 20 April 2015 / Published: 24 April 2015 Abstract: In this work, it is argued that effective protection of geological objects displaying heritage value requires the local community’s involvement in all geoconservation actions, i.e., inventory, evaluation, conservation, valuation and monitoring procedures, and not only at the final part of the process, when it is expected from local communities that the physical integrity of such objects is guaranteed. Community involvement in geoheritage inventory and evaluation procedures can be appraised by using a classification system that integrates both the geoheritage properties displayed by the geological objects and usually recognized by geoscientists (i.e., relevance grade) and the social role attributed to geological objects by communities outside Earth scientists that arise from the public perception of such objects (i.e., abstract perceptiveness).
    [Show full text]
  • Two Contrasting Phanerozoic Orogenic Systems Revealed by Hafnium Isotope Data William J
    ARTICLES PUBLISHED ONLINE: 17 APRIL 2011 | DOI: 10.1038/NGEO1127 Two contrasting Phanerozoic orogenic systems revealed by hafnium isotope data William J. Collins1*(, Elena A. Belousova2, Anthony I. S. Kemp1 and J. Brendan Murphy3 Two fundamentally different orogenic systems have existed on Earth throughout the Phanerozoic. Circum-Pacific accretionary orogens are the external orogenic system formed around the Pacific rim, where oceanic lithosphere semicontinuously subducts beneath continental lithosphere. In contrast, the internal orogenic system is found in Europe and Asia as the collage of collisional mountain belts, formed during the collision between continental crustal fragments. External orogenic systems form at the boundary of large underlying mantle convection cells, whereas internal orogens form within one supercell. Here we present a compilation of hafnium isotope data from zircon minerals collected from orogens worldwide. We find that the range of hafnium isotope signatures for the external orogenic system narrows and trends towards more radiogenic compositions since 550 Myr ago. By contrast, the range of signatures from the internal orogenic system broadens since 550 Myr ago. We suggest that for the external system, the lower crust and lithospheric mantle beneath the overriding continent is removed during subduction and replaced by newly formed crust, which generates the radiogenic hafnium signature when remelted. For the internal orogenic system, the lower crust and lithospheric mantle is instead eventually replaced by more continental lithosphere from a collided continental fragment. Our suggested model provides a simple basis for unravelling the global geodynamic evolution of the ancient Earth. resent-day orogens of contrasting character can be reduced to which probably began by the Early Ordovician12, and the Early two types on Earth, dominantly accretionary or dominantly Paleozoic accretionary orogens in the easternmost Altaids of Pcollisional, because only the latter are associated with Wilson Asia13.
    [Show full text]
  • Balkatach Hypothesis: a New Model for the Evolution of the Pacific, Tethyan, and Paleo-Asian Oceanic Domains
    Research Paper GEOSPHERE Balkatach hypothesis: A new model for the evolution of the Pacific, Tethyan, and Paleo-Asian oceanic domains 1,2 2 GEOSPHERE, v. 13, no. 5 Andrew V. Zuza and An Yin 1Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada 89557, USA 2Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095-1567, USA doi:10.1130/GES01463.1 18 figures; 2 tables; 1 supplemental file ABSTRACT suturing. (5) The closure of the Paleo-Asian Ocean in the early Permian was accompanied by a widespread magmatic flare up, which may have been CORRESPONDENCE: avz5818@gmail .com; The Phanerozoic history of the Paleo-Asian, Tethyan, and Pacific oceanic related to the avalanche of the subducted oceanic slabs of the Paleo-Asian azuza@unr .edu domains is important for unraveling the tectonic evolution of the Eurasian Ocean across the 660 km phase boundary in the mantle. (6) The closure of the and Laurentian continents. The validity of existing models that account for Paleo-Tethys against the southern margin of Balkatach proceeded diachro- CITATION: Zuza, A.V., and Yin, A., 2017, Balkatach hypothesis: A new model for the evolution of the the development and closure of the Paleo-Asian and Tethyan Oceans criti- nously, from west to east, in the Triassic–Jurassic. Pacific, Tethyan, and Paleo-Asian oceanic domains: cally depends on the assumed initial configuration and relative positions of Geosphere, v. 13, no. 5, p. 1664–1712, doi:10.1130 the Precambrian cratons that separate the two oceanic domains, including /GES01463.1. the North China, Tarim, Karakum, Turan, and southern Baltica cratons.
    [Show full text]
  • Scottish Missionaries and the Circumcision Controversy in Kenya 1900-1960
    International Review of Scottish Studies Vol. 28 2003 Kenneth Mufaka SCOTTISH MISSIONARIES AND THE CIRCUMCISION CONTROVERSY IN KENYA 1900-1960 t the turn of the century, the British High Commis- sioner in East Africa set up various areas in which A Christian missionaries were allowed exclusive influence. Scottish missionaries served the largest and most politically astute tribe in Kenya, the Kikuyu. Scottish educa- tion, combining a theoretical base with vocational training, attracted the best and the brightest of Kikuyu youths. This type of education provided a basis for future employment in government and industry. Jomo Kenyatta and Mbui Koinanage, both future nationalist leaders of Kenya, were converts and protégés of Scottish missionaries. However, in 1929, a sudden rift occurred between the Kikuyu Christian elders and congregations on one hand and their Scottish missionary patrons on the other side. The rift came about when the Scottish missionaries insisted that all Kikuyu Christians should take an oath against female initiation. Two thirds of the Kikuyu Christians left the mission church to form their own nationalist oriented churches. The rise of nationalistic feeling among Kenyans can be traced to this controversy. The issue of female circum- cision seems to have touched on all the major ingredients that formed the basis of African nationalist alienation from colo- nial rule. This article argues that the drama of 1929 was a rehearsal of the larger drama of the Mau Mau in 1950-1960 that put an end to colonial rule in Kenya. Though initiation practices were widespread in Kenya and the neighboring Sudan, the Scottish missionaries were unaware of them until 1904.
    [Show full text]
  • Deconvolving the Pre-Himalayan Indian Margin E Tales of Crustal Growth and Destruction
    Geoscience Frontiers 10 (2019) 863e872 HOSTED BY Contents lists available at ScienceDirect China University of Geosciences (Beijing) Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Research Paper Deconvolving the pre-Himalayan Indian margin e Tales of crustal growth and destruction Christopher J. Spencer a,b,*, Brendan Dyck c, Catherine M. Mottram d,e, Nick M.W. Roberts b, Wei-Hua Yao a,f, Erin L. Martin a a Earth Dynamics Research Group, The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, 6845, Perth, Australia b NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK c Department of Earth Sciences, Simon Fraser University, University Drive, Burnaby V5A 1S6, Canada d Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK e School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, PO1 3QL, UK f Schoolof Earth Sciences and Engineering, SunYat-sen University, Guangzhou 510275, China article info abstract Article history: The metamorphic core of the Himalaya is composed of Indian cratonic rocks with two distinct crustal Received 30 November 2017 affinities that are defined by radiogenic isotopic geochemistry and detrital zircon age spectra. One is Received in revised form derived predominantly from the Paleoproterozoic and Archean rocks of the Indian cratonic interior and is 4 February 2018 either represented as metamorphosed sedimentary rocks of the Lesser Himalayan Sequence (LHS) or as Accepted 22 February 2018 slices of the distal cratonic margin. The other is the Greater Himalayan Sequence (GHS) whose prove- Available online 16 March 2018 nance is less clear and has an enigmatic affinity.
    [Show full text]
  • Locating South China in Rodinia and Gondwana: a Fragment of Greater India Lithosphere?
    Locating South China in Rodinia and Gondwana: A fragment of greater India lithosphere? Peter A. Cawood1, 2, Yuejun Wang3, Yajun Xu4, and Guochun Zhao5 1Department of Earth Sciences, University of St Andrews, North Street, St Andrews KY16 9AL, UK 2Centre for Exploration Targeting, School of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia 3State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 4State Key Laboratory of Biogeology and Environmental Geology, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 5Department of Earth Sciences, University of Hong Kong, Pokfulam Road, Hong Kong, China ABSTRACT metamorphosed Neoproterozoic strata and From the formation of Rodinia at the end of the Mesoproterozoic to the commencement unmetamorphosed Sinian cover (Fig. 1; Zhao of Pangea breakup at the end of the Paleozoic, the South China craton fi rst formed and then and Cawood, 2012). The Cathaysia block is com- occupied a position adjacent to Western Australia and northern India. Early Neoproterozoic posed predominantly of Neoproterozoic meta- suprasubduction zone magmatic arc-backarc assemblages in the craton range in age from ca. morphic rocks, with minor Paleoproterozoic and 1000 Ma to 820 Ma and display a sequential northwest decrease in age. These relations sug- Mesoproterozoic lithologies. Archean basement gest formation and closure of arc systems through southeast-directed subduction, resulting is poorly exposed and largely inferred from the in progressive northwestward accretion onto the periphery of an already assembled Rodinia. presence of minor inherited and/or xenocrys- Siliciclastic units within an early Paleozoic succession that transgresses across the craton were tic zircons in younger rocks (Fig.
    [Show full text]
  • Springer Geology More Information About This Series at Mingguo Zhai Editor
    Springer Geology More information about this series at http://www.springer.com/series/10172 Mingguo Zhai Editor Precambrian Geology of China 123 Editor Mingguo Zhai Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China ISSN 2197-9545 ISSN 2197-9553 (electronic) Springer Geology ISBN 978-3-662-47884-4 ISBN 978-3-662-47885-1 (eBook) DOI 10.1007/978-3-662-47885-1 Library of Congress Control Number: 2015944154 Springer Heidelberg New York Dordrecht London © Springer-Verlag Berlin Heidelberg 2015 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper Springer-Verlag GmbH Berlin Heidelberg is part of Springer Science+Business Media (www.springer.com) Preface The Precambrian (4560–541 Ma) covers almost 90 % of the planet Earth’s history.
    [Show full text]
  • RESEARCH Geochronology and Geochemistry of Neoproterozoic
    RESEARCH Geochronology and geochemistry of Neoproterozoic granitoids in the central Qilian Shan of northern Tibet: Reconstructing the amalgamation processes and tectonic history of Asia Chen Wu1,*, Andrew V. Zuza2,3, An Yin1,2, Changfeng Liu4, Robin C. Reith2, Jinyu Zhang5, Wencan Liu4, and Zhiguang Zhou1 1STRUCTURAL GEOLOGY GROUP, CHINA UNIVERSITY OF GEOSCIENCES (BEIJING), BEIJING 100083, CHINA 2DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES, UNIVERSITY OF CALIFORNIA, LOS ANGELES, CALIFORNIA 90095-1567, USA 3NEVADA BUREAU OF MINES AND GEOLOGY, UNIVERSITY OF NEVADA, RENO, NEVADA 89557, USA 4INSTITUTE OF GEOLOGICAL SURVEY, CHINA UNIVERSITY OF GEOSCIENCES (BEIJING), BEIJING 100083, CHINA 5INSTITUTE OF GEOLOGY, CHINA EARTHQUAKE ADMINISTRATION, BEIJING 100029, CHINA ABSTRACT Our understanding of the assembly history of Asia depends critically on the tectonic relationships between its major cratons, including Siberia, North China, South China, and Tarim. The intervening microcontinents between these cratons can provide insight into the paleogeographic and paleotectonic relationships of the cratons, but there is currently a general lack of knowledge regarding the basement geology of these microcontinents. Here we present results from systematic geologic mapping, U-Pb zircon dating, whole-rock geochemical analysis, and syn- thesis of existing data to establish the Proterozoic to early Paleozoic evolution of the central Qilian basement to the south of the North China craton in northwest China. Our results indicate that the region underwent three major periods of magmatic activity at 960–880, 877–710, and 550–375 Ma. Our geochemical analysis suggests that the ca. 900 Ma plutons were generated during arc magmatism and/or syncollisional crustal melting, whereas the ca. 820 Ma plutons are A-type granitoids, which are typically associated with extensional tectonism.
    [Show full text]
  • Where Is (And Was) Pennsylvania?”
    Essay: “Where Is (and Was) Pennsylvania?” W.E. Hamilton D.Y. Sillman Penn State University This work is licensed under a Creative Commons Attribution‐Noncommercial‐No Derivative Works 3.0 license. It may be distributed and shared, with attribution, but not altered or used commercially in any way. “Where Is (and Was) Pennsylvania?” Pennsylvania is a pretty obvious place to us. It’s a rectangular, politically defined piece of the eastern United States with a wiggly eastern border that follows the Delaware River and three, very straight other borders on the north, west, and south that were laboriously marked off after a great deal of social and legal travail and even some violence. It’s a hilly to mountainous, river‐rich place with forests and fields and cities. Its statistics are simple: it is about three hundred miles from east to west and a little less than one hundred and seventy miles from south to north. It comprises 46,058 square miles (although the number “45,308” shows up in some references). Its latitude range is thirty‐nine degrees forty‐three minutes N to forty‐two degrees N, and its longitude range is seventy‐four degrees and forty‐three minutes W to eighty degrees thirty‐one minutes W (Netstate 2008). This Pennsylvania, though, hasn’t always been all of that. The great rectangle of Pennsylvania has been, through the geological history of the Earth, in the southern hemisphere, on the equator, and in a great many places in between. It has been oriented with its long, three hundred mile axis east to west and also with this long axis running south to north.
    [Show full text]
  • Terminal Suturing of Gondwana Along the Southern Margin of South China Craton: Evidence from Detrital Zircon U-Pb Ages and Hf Is
    PUBLICATIONS Tectonics RESEARCH ARTICLE Terminal suturing of Gondwana along the southern 10.1002/2014TC003748 margin of South China Craton: Evidence from detrital Key Points: zircon U-Pb ages and Hf isotopes in Cambrian • Sanya of Hainan Island, China was linked with Western Australia in and Ordovician strata, Hainan Island the Cambrian • Sanya had not juxtaposed with South Yajun Xu1,2,3, Peter A. Cawood3,4, Yuansheng Du1,2, Zengqiu Zhong2, and Nigel C. Hughes5 China until the Ordovician • Gondwana terminally suture along the 1State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of southern margin of South China Geosciences, Wuhan, China, 2State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China, 3Department of Earth Sciences, University of St. Andrews, St. Andrews, UK, Supporting Information: 4Centre for Exploration Targeting, School of Earth and Environment, University of Western Australia, Crawley, Western • Readme Australia, Australia, 5Department of Earth Sciences, University of California, Riverside, California, USA • Figure S1 • Figure S2 • Table S1 • Table S2 Abstract Hainan Island, located near the southern end of mainland South China, consists of the Qiongzhong Block to the north and the Sanya Block to the south. In the Cambrian, these blocks were Correspondence to: separated by an intervening ocean. U-Pb ages and Hf isotope compositions of detrital zircons from the Y. Du, Cambrian succession in the Sanya Block suggest that the unit contains detritus derived from late [email protected] Paleoproterozoic and Mesoproterozoic units along the western margin of the West Australia Craton (e.g., Northampton Complex) or the Albany-Fraser-Wilkes orogen, which separates the West Australia and Citation: Mawson cratons.
    [Show full text]
  • Neoproterozoic Geology and Reconstruction of South China
    Accepted Manuscript Neoproterozoic geology and reconstruction of South China Jun-Hong Zhao, Shao-Bing Zhang, Xiao-Lei Wang PII: S0301-9268(18)30081-0 DOI: https://doi.org/10.1016/j.precamres.2018.02.004 Reference: PRECAM 5015 To appear in: Precambrian Research Received Date: 3 February 2018 Accepted Date: 10 February 2018 Please cite this article as: J-H. Zhao, S-B. Zhang, X-L. Wang, Neoproterozoic geology and reconstruction of South China, Precambrian Research (2018), doi: https://doi.org/10.1016/j.precamres.2018.02.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Neoproterozoic geology and reconstruction of South China Jun-Hong Zhaoa*，Shao-Bing Zhangb, Xiao-Lei Wangc a State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China. b CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China. c State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China. *Corresponding author: State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China Email address: [email protected] ABSTRACT 1 The South China Craton, as one of the largest continental blocks in China, has been considered as a key element in the Rodinia supercontinent.
    [Show full text]
  • Earth History
    Earth History Geography 106 LRS Doug Fischer Introduction – Overview of geologic history • Plate positions over time • Major biogeographic events Earth’s tectonic history • Gondwanaland – Southern continents – Formed 650mya Precambrian • Laurasia – Northern Continents – Most converged in Devonian 400mya as “old sandstone continent” • Formation of Pangaea – Late Permian ~ 275 mya Breakup of Pangaea • Started 180 mya (early Jurassic) – Prior to breakup, great mixing of biota – However, regionalization did still occur as it does on (smaller) continents today Breakup of Laurasia • Separated Europe & N. America 100 mya • Beringia rejoined them 75 mya • Intermittent connection via Greenland & Beringia through Tertiary Breakup of Gondwanaland • 180-160mya Gondwanaland started to split – Mesozoic (Triassic/Jurassic) • Mostly finished by 90 mya 152 mya 94 mya Central America and Antilles • Caribbean Plate was sandwiched between N&S America between 80 and 20 mya • Formed ring of islands • Landbridge closed ~ 3.5 mya – Great American Interchange 14 mya Biogeographic consequences of plate tectonics • Fragmentation and dispersal of ancestral biota (vicariance) • Changing barriers and coridors – biotic interchange • Speciation and extinction – changing physical and biological conditions Tour of Geologic History The geologic time scale • Phanerozoic starts with Cambrian explosion of species with hard body parts – (Some multi- cellular algae and animals lived at the end of the Precambrian) Paleozoic Paleozoic Cambrian • Animals with hard-shells appeared in great numbers for the first time • The continents were flooded by shallow seas. • The supercontinent of Gondwana had just formed and was located near the South Pole. Ordivician • ancient oceans separated the barren continents of Laurentia, Baltica, Siberia and Gondwana. • The end of the Ordovician was one of the coldest times in Earth history.
    [Show full text]