A Paleoproterozoic ophiolitic mélange, Yangtze craton, South China: Evidence for Paleoproterozoic suturing and microcontinent amalgamation Qingsen Han a , Songbai Peng a,⇑ , Timothy Kusky a , Ali Polat b,a , Xingfu Jiang c , Yang Cen d , Songfeng Liu a , Hao Deng a a School of Earth Sciences, Center for Global Tectonics, and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China b Department of Earth and Environmental Sciences, University of Windsor, Windsor, ON N9B3P4, Canada c College of Earth Sciences, East China Institute of Technology, Nanchang 330013, China d Geotechnical Engineering Institute, Zhejiang Guangchuan Engineering Consultation Co, Ltd, Hangzhou 310020, China article info Article history: Received 27 November 2016 Revised 27 February 2017 Accepted 6 March 2017 Available online 7 March 2017 Keywords: Yangtze craton Huangling Dome Paleoproterozoic Shuiyuesi ophiolitic mélange Columbia supercontinent abstract We document for the first time the presence of a Paleoproterozoic ophiolitic mélange in the Archean– Paleoproterozoic Kongling Complex in the northern Huangling Dome, Yangtze craton, South China. Detailed field mapping, petrographic, geochronological and geochemical studies reveal that the mélange consists of a suite of amphibolite facies mafic and ultramafic tectonic blocks including serpentinized harzburgite, olivine pyroxenite, pyroxenite, diabase, gabbro and basalt dispersed in a strongly sheared metasedimentary matrix. The mélange displays polyphase deformation and northwest-verging nappe structures, and underwent amphibolite to granulite facies metamorphism in the Paleoproterozoic (2.0– 1.95 Ga). The metasedimentary rocks are composed mainly of garnet-biotite-plagioclase gneiss, mica schist, mica-graphite schist, marble, quartzite, and banded iron formation (BIF). The mafic–ultramafic rock association shares the lithological and geochemical characteristics of Phanerozoic suprasubduction zone ophiolites. LA-ICP-MS U–Pb dating of zircons from the diabase yield ages between 2142 and 2148 Ma for the mag- matic cores and between 2042–2048 Ma for the metamorphic rims. Zircon cores have e Hf (t) values rang- ing from +5.4 to +10.3 (average = +7.2) with corresponding T DM1 ages of 2.24 Ga, indicating that these rocks are remnants of juvenile crust derived from the depleted mantle at ca. 2.2 Ga. All rock types in the mélange underwent Paleoproterozoic (2.0–1.95 Ga) amphibolite–granulite facies metamorphism and were intruded by syn-metamorphic granite (2.0 Ga), post-collisional (ca.1.85 Ga) granite and mafic dykes. Intrusion age of one quartz monzonitic dyke crosscutting the serpentinized harzburgite is 1999 Ma, constraining the minimum emplacement age of the mafic–ultramafic complex. The mafic–ul- tramafic rocks within the metasedimentary matrix in the northern Huangling Dome are fragments of a ca. 2.15 Ga suprasubduction zone ophiolite that was incorporated into the suture zone during the accretionary-collisional process. The mélange recognized in the northern Yangtze craton provides impor- tant evidence for the Paleoproterozoic subduction and accretion processes possibly associated with the amalgamation of the proposed Columbia supercontinent. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Suture zones mark locations where ancient oceans closed, and thus are remnants of ancient subduction zones. Suture zones are typically characterized by structurally complex rock units such as mélanges and ophiolites (Dewey, 1977; S ßengör et al., 1978; Cawood et al., 2009; Wakabayashi and Dilek, 2011; Kusky et al., 2013). Tectonic mélange widely appears in many different oro- genic belts and is one of the notable litho-tectonic units within subduction-accretion complexes, recording the accretion process at active convergent plate margins, and later emplacement- related fabrics (Kusky et al., 1997, 2013; Kusky and Polat, 1999; Wakabayashi and Dilek, 2011; Festa et al., 2012; Polat et al., 2015). Ophiolites represent fragments of ancient oceanic lithosphere that are tectonically accreted to or emplaced over http://dx.doi.org/10.1016/j.precamres.2017.03.004 0301-9268/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: psongbai@aliyun.com (S. Peng). Precambrian Research 293 (2017) 13–38 Contents lists available at ScienceDirect Precambrian Research journal homepage: www.elsevier.com/locate/precamres