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Locating South China in Rodinia and Gondwana: a Fragment of Greater India Lithosphere?

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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. 1; Zhao and derived from the southeast and include detritus from beyond the current limits of the cra- Cawood, 2012). One marked difference between ton. Detrital zircon age spectra require an East Gondwana source and are very similar to the Cathaysia and Yangtze blocks is that the for- the Tethyan Himalaya and younger Paleozoic successions from Western Australia, suggesting mer underwent a tectonothermal event in the derivation from a common source and by inference accumulation in linked basins along the early Paleozoic (460–420 Ma), which resulted in northern margin of Gondwana, a situation that continued until rifting and breakup of the an angular unconformity between post-Silurian craton in the late Paleozoic. cover and metamorphosed pre-Devonian strata with granites emplaced in Cathaysia and adja- INTRODUCTION al., 2011; Zhou et al., 2002). Uncertainties in cent areas in the Yangtze block (Huang, 1977; The confi gurations of the supercontinents of paleogeographic reconstructions such as those Wang et al., 2013a). This led some research- Gondwana and Pangea are relatively well con- proposed for South China in Rodinia refl ect the ers to regard the Cathaysia block as an early strained (Veevers, 2004), whereas those of older incomplete nature of available data sets, result- Paleozoic folded belt bordering the southeast- supercontinents are debated; competing models ing in signifi cant gaps in the geologic record and ern margin of the Yangtze block (Huang, 1977), have been proposed (e.g., Li et al., 2008; Zhang allowing for multiple nonunique interpretations. although most researchers favor models that et al., 2012; Zhao et al., 2002). This is particu- Thus, limiting the position of even one block regard Cathaysia as a discrete continental block larly the case with the end-Mesoproterozoic with respect to another in supercontinent recon- that amalgamated with the Yangtze block in the supercontinent of Rodinia, the confi guration of structions is signifi cant, because changes in the early Neoproterozoic (see Zhao and Cawood, which remains controversial (e.g., Evans, 2009; history of one segment must be accommodated 2012, and references therein). In addition, some Li et al., 2008). At the heart of the controversy in the arrangement of others, and will ultimately of the Precambrian to early Paleozoic rocks in is the position of South China craton in Rodinia; limit possible interrelationships between all the Cathaysia block were strongly reworked by the consensus model proposes that it occupied other blocks. In this paper we summarize geo- a Late Permian–Early Triassic event, but its tec- an intracratonic position between Laurentia logical, geochronological, geochemical, and tonic nature remains unknown or controversial and Australia (Li et al., 2008, and references detrital zircon isotopic data for the Neoprotero- (Zhao and Cawood, 2012). therein), whereas other models argue that it was zoic and Paleozoic rock units from the South either on the margin of Rodinia near Australia China craton. We show that throughout this time Yangtze-Cathaysia Boundary and Relation (Zhao and Cawood, 1999; Zhou et al., 2002) or frame it was fi rst assembled on, and then was to Rodinia occupied a position external to the superconti- adjacent to, the Western Australia and northern Establishing the nature and age of the bound- nent (Yang et al., 2004). The consensus model India margins of both Rodinia and Gondwana, ary between the constituent Yangtze and Cathay- assumes that the pre–850 Ma rocks in the South prior to rifting off Pangea and fi nally colliding sia blocks, generally considered to be delin- China craton formed in a collisional orogen with Asia to achieve its current position. eated by the Sibao (or Jiangnan) orogen (Fig. 1; (termed the Sibao or Jiangnan orogen), coinci- e.g., Li et al., 2008; Zhao and Cawood, 1999), dent with the assembly of the Rodinia. Younger SETTING OF SOUTH CHINA is critical to understanding the setting of the 830–750 Ma igneous rocks in South China are The South China craton consists of the South China craton. Recent work has shown considered the products of anorogenic mag- Yangtze block to the northwest and the Cathay- that rather than a single boundary, the eastern matism in intracontinental rift basins related sia block to the southeast (Fig. 1; Zhao and portion of the craton can be subdivided into to mantle plume activity during the breakup of Cawood, 2012). The Yangtze block consists of a series of structural blocks: eastern Cathay- Rodinia. In contrast, other models argued that Archean–Paleoproterozoic crystalline base- sia, western Cathaysia, and eastern Yangtze, early to middle Neoproterozoic igneous rock ment surrounded by late Mesoproterozoic to which are bounded on their western sides by assemblages exposed along the margins of early Neoproterozoic folded belts, which are the Zhenghe-Dapu-Gaoyao-Huilai fault system, the craton developed in arc systems (Zhao et locally unconformably overlain by weakly the Jiangshan-Shaoxing fault system, and the GEOLOGY, August 2013; v. 41; no. 8; p. 903–906; Data Repository item 2013248 doi:10.1130/G34395.1 | Published online 6 June 2013 GEOLOGY© 2013 Geological | August Society 2013 of | America.www.gsapubs.org Gold Open Access: This paper is published under the terms of the CC-BY license. 903 Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/41/8/903/3546122/903.pdf by guest on 30 September 2021 100°E 110 °E 120°E Hf/3 North China Craton Songpan-Ganzi Wuyi-Yunkai Bikou Qinling-D Shanghai Hannan A N-MORB Jiangnan abie lt Shuangxiwu 30° N Fau Kongling lt Longmenshan Fault IAT Fau dezhen 30° N Panxi-Hannan fold belt Shuangxiwu Kangding Jing Shaoxing Central & Jiangnan n- i ngsha West Yangtze anzha Jia E-MORB ifeng-W Fault Y Wuyi apu B lt he-D West CA Jiangnan Zheng Cathaysia WPAB cheng Fau Kunming Fault Nanling Pacific Ocean Anhua-Luo Ailaoshan Th Nb/16 -Huilai East Cathaysia East Yangtze Gaoyao Chenzhou-Linwu North China Yunkai B N-MORB Yangtze Shanghai Son Hong Kong NE Jiangxi Province gma Fault Jiangnan Domain 10 en rog o O Indochina Siba fined Nb/Th E-MORB and OIB de ly- 20° N us Cathaysia evio Hainan Pr 0 360 km Arc volcanic rocks or crustal contamination 1 100°E 110 °E 0.1 1.0 10 Archean basement in Yangtze block Paleoproterozoic basement in Yangtze block Mesoproterozoic and Neoproterozoic strata in Yangtze block La/Nb Neoproterozoic (970-750 Ma arc- and/or rift-related plutonic complexes and supracrustal rocks in Panxi-Hannan and Jiangnam belts 8.0 Early Neoproterozoic (850-825 Ma) metamorphosed volcanic-sedimentary units (Sibao Group and equivalents) in Jiangnan belt Depleted mantle +slab-derived fluid Middle Neoproterozoic (825-750 Ma) weakly metamorphosed cover (Banxi Group and equivalents) in Jiangnan belt 4.0 Late Neoproterozoic (750-542 Ma) unmetamorphosed cover in Yangtze block and Jiangnan belt 825-800 Ma granite in Jiangnan belt Middle Neoproterozoic (820-750 Ma) Banxi Group and equivalents reworked by early Paleozoic ogogeny (460-420 Ma) in Jiangnan belt 0.0 Hidden early Paleozoic fold belt, Cathaysia block Paleoproterozoic basement, Cathaysia block reworked in Triassic (250-230 Ma) Nd(t) ( Ma) -4.0 Meso-Neoproterozoic basement, Cathaysia block (Baoban Group, Hainan Island) ε Early Neoproterozoic (860-820 Ma) volcanic-sedimentary units reworked in early Paleozoic (460-420 Ma) in Cathaysia block and Jiangnan belt -8.0 Late Neoproterozoic to early Paleozoic volcanic-sedimentary units metamorphosed during early Paleozoic orogenesis (460-420 Ma) in Cathaysia block South China C sediment -12.0 Figure 1. Map of south China (after Zhao and Cawood, 2012) with inset showing Sibao oro- 0.01 0.1 1.0 10.0 gen (after Li et al., 2002). Nb/Y Figure 2. Geochemical plots for mafi c rocks along Wuyi-Yunkai, Shuangxiwu, and Jiang- Jingdezhen-Yifeng-Wanzhai-Anhua-Luochheng sources of the data is provided in the GSA Data nan domains in eastern South China craton. fault system, respectively (Fig. 1; Wang et al., Repository1 (Fig. 2; Shu, 2006; Wang et al., A: Hf/3–Th–Nb/16. B: Nb/Th versus La/Nb. C: ε versus Nb/Y.
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