The Central Ailaoshan ophiolite and modern analogs Chun-Kit Lai a, ⁎, Sebastien Meffre a , Anthony J. Crawford a , Khin Zaw a , Jacqueline A. Halpin a , Chuan-Dong Xue b , Abhisit Salam a a ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Tasmania, Australia b Faculty of Land Resource Engineering, Kunming University of Science and Technology, China abstract article info Article history: Received 12 June 2012 Received in revised form 2 March 2013 Accepted 2 March 2013 Available online 22 March 2013 Keywords: Jinshajiang–Ailaoshan–Song Ma suture Ophiolite Paleotethys Gondwana volcanic passive margin South China–Indochina collision The Central Ailaoshan (CAL) ophiolite represents an important tectonic component of the Jinshajiang– Ailaoshan–Song Ma suture zone separating the South China and Indochina blocks in the mainland SE Asia. The CAL ophiolite occurs as a complex tectonic mélange, and preserves the history of the opening and closure of the once vast Jinshajiang–Ailaoshan–Song Ma branch of the Paleotethys. New and existing geological data indicate that the CAL ophiolite contains magmatic rocks generated by: (1) L. Devonian–E. Carboniferous (ca. 380–330 Ma) volcanic passive margin-breakup development in the NW Gondwana margin; (2) L. Permian (ca. 258 Ma) Emeishan large igneous province-related continental rift magmatism, together with (and intruded by) (3) earliest M. Triassic (ca. 244 Ma) continent–continent syn-collisional S-type granitoids. The Devono-Carboniferous suites of the CAL ophiolite are highly comparable with many continental margin-type Alpine Tethyan ophiolites. In addition, the various CAL magmatic suites have strong South China block-affinities with coeval magmatism particularly in the western South China block, Jinshajiang-, Song Ma-, and Song Da terranes. © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. 1. Introduction Ophiolites represent slices of oceanic crust and upper mantle tectonically displaced onto continental margins during subduction– accretions, arc–continent/continent–continent collisions and ridge– trench interactions (e.g., Anonymous, 1972; Dilek, 2003; Cawood et al., 2009; Dilek and Furnes, 2011). Early works in the classical Semail ophiolite in Oman (e.g., Lippard et al., 1986; Hacker and Mosenfelder, 1996) and Troodos ophiolite in Cyprus (e.g., Gass, 1968; Miyashiro, 1973; Robertson and Xenophontos, 1993; Robinson et al., 2003) have led to the long perceptions that ophiolites were largely originat- ed from an arc/backarc basin setting. With the advances in the under- standing on geochemistry, geochronology and modern tectonic analogs, it is now clear that ophiolites have been derived from or as- sociated with a wide variety of tectonic settings, including mid-ocean ridge (MOR) (e.g., Kamenetsky et al., 2000; Shibuya et al., 2007), forearc/arc/backarc basin (e.g., Dilek et al., 2007; Dilek and Furnes, 2009; Dilek and Thy, 2009; Pearce and Robinson, 2010; Santosh et al., 2012), seamount/oceanic plateau (e.g., Eddy et al., 1998; Ichiyama et al., 2008; Yang et al., 2012), large igneous province (LIP) (e.g., Dilek and Ernst, 2008; Xiao et al., 2008), continental margin (e.g., Costa and Caby, 2001; Garuti et al., 2011; Montanini et al., 2011) and accretionary complexes (e.g, Safonova and Santosh, 2014; Santosh et al., 2013). For the case of the CAL ophiolite, previous studies have mainly advocated an MOR (i.e., large and long existing ocean similar to the main Paleotethys; e.g., Shen et al., 1998a; Wei and Shen, 1995), backarc basin (e.g., Wang et al., 2000), small ocean basin (Yumul et al., 2008), or ‘non-volcanic segment of a rifted conti- nental margin’ (Jian et al., 2009a) setting. To resolve this controversy, this paper presents the results of a regional geological research aimed at unraveling the temporal– magmatic relationships among key magmatic suites in the CAL ophiolite. Understanding the geological evolution of the CAL ophiolite is important as it is on the South China–Indochina suture zone, and therefore provides insights into how and when the largest pieces of SE Asia were rifted from the northern Gondwana margin and later reassembled in the present day location. Research on the CAL ophiolite is also of global significance because it provides an important case study for Paleotethyan ophiolites, as well as a tectonic framework for the eruption of the Emeishan large igneous province (ELIP), which is widely considered to be responsible for the Guadeloupian (L. Permian) mass extinction event (Zhou et al., 2002; B. He et al., 2010; Shellnutt et al., 2012). Our new tectonic model incorporating the CAL ophiolite into the bigger mainland SE Asia framework is described in Lai et al. (2014-this issue). 2. Geological background The Ailaoshan fold belt, ca. 500 km long and 20–100 km wide, ex- tends NW–SE across southwestern Yunnan. The fold belt is bounded by the Simao Terrane (Indochina) to its west and by the South Gondwana Research 26 (2014) 75–88 ⁎ Corresponding author. Tel.: +61 3 6226 2390; fax: +61 3 6226 7662. E-mail address: chunkitl@utas.edu.au (C.-K. Lai). 1342-937X/$ – see front matter © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gr.2013.03.004 Contents lists available at ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr