Author's personal copy Discussion Comment on “An alternative plate tectonic model for the Palaeozoic–Early Mesozoic Palaeotethyan evolution of Southeast Asia (Northern Thailand–Burma)” by O.M. Ferrari, C. Hochard & G.M. Stampfli, Tectonophysics 451, 346-365 (doi:10.1016/j.tecto.2007.11.065) I. Metcalfe Earth Sciences/Geology, School of Environmental and Rural Science, University of New England, Armidale NSW 2351, Australia abstract article info Article history: Received 1 April 2008 Received in revised form 22 December 2008 Accepted 26 January 2009 Available online 3 February 2009 Keywords: Southeast Asia Shan-Thai Palaeo-Tethys suture zone Gondwana Cathaysian Ferrari et al. [Ferrari, O.M., Hochard, C., Stampfli, G.M., 2008. An alternative plate tectonic model for the Palaeozoic–Early Mesozoic Palaeotethyan evolution of Southeast Asia (Northern Thailand–Burma). Tectonophysics 451, 346–365. doi:10.1016/j.tecto.2007.11.065.] redefine the “Shan-Thai” terrane in Thailand as a Cathaysian Indochina-derived terrane when this has traditionally been defined and used as a Gondwana-derived continental block, hence introducing unnecessary confusion. In their definition of “Shan-Thai”, they also inappropriately combine oceanic suture zone rocks (the Palaeo-Tethys Inthanon suture) and continental arc rocks (Sukhothai Island Arc system). The Mai Yuam Fault, identified by Ferrari et al. (2008) as the Palaeo-Tethys suture, is in fact a Cenozoic fault and the Palaeo-Tethys suture zone is represented by the Inthanon Suture zone in Thailand which is equivalent to the previously recognised Inthanon zone. The concept of derivation of “Orang Laut” terranes from South China-Indochina by back-arc spreading is innovative but the proposed Permo-Triassic back-arc along the Song Da/Song Ma zone in Vietnam is less convincing. There is little evidence to support the proposed southwards subduction of Palaeo-Tethys beneath eastern Gondwana in the Permian. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Ferrari et al. (2008) present a new model for the geodynamic evolution of Southeast Asia in which they particularly focus on the northern Thailand–Burma region. Ferrari et al. claim to use a “modern plate tectonic model” for their reconstructions as compared to “classical continental drift models proposed so far”. They also discuss the location of the Palaeotethys suture in Thailand, and propose the Tertiary Mae Yuam Fault to represent this suture. The “Shan-Thai” block is also re-defined in this paper and a new “Orang Laut terranes concept” is introduced. I have serious concerns with some of the interpretations presented by Ferrari et al., and also with their use of the term “Shan-Thai”. I here present some discussion and alternative interpretations and comments on the geodynamic framework and evolution of Thailand and Southeast Asia and on what I consider to be inappropriate terrane definitions and terminology. 2. Plate reconstruction methodology and plate reconstructions I congratulate Ferrari et al. (2008) on the general approach to plate and palaeogeographic reconstruction, particularly in using a quanti- tative based model that takes into account relative plate motions and velocities on a sphere in combination with a range of multi- disciplinary geological and geophysical data for the region that can be incorporated from GIS databases. I do however feel that it is an exaggerated claim that the authors are the first to use this “modern” approach and the various reconstructions of Scotese et al. (1999), Scotese (2004), Dercourt et al. (1993), Hall (2002), Rosenbaum et al. (2002), Torsvik and Cocks (2004), Golonka (2007) serve as a few examples of such previous approaches. In my own reconstructions of the SE Asian region (e.g. Metcalfe, 1988, 1991, 1994, 2002a, 2005, 2006), I have also taken a range of multi-disciplinary data into account, including quantitative data such as palaeomagnetism and isotope geochronology, and a range of other semi-quantitative and qualitative data including biogeographic, stratigraphic and sedimen- tological data. It has long been demonstrated that plate and palaeogeographic reconstructions based solely on quantitative data or solely on qualitative data can produce both inaccurate and highly misleading reconstructions and interpretations. I have been long convinced that a truly multi-disciplinary approach is essential and I Tectonophysics 471 (2009) 329–332 E-mail address: imetcal2@une.edu.au. Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto 0040-1951/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2009.01.022