1 3 Int J Earth Sci (Geol Rundsch) DOI 10.1007/s00531-016-1337-9 ORIGINAL PAPER Stages of late Paleozoic to early Mesozoic magmatism in the Song Ma belt, NW Vietnam: evidence from zircon U–Pb geochronology and Hf isotope composition Pham Trung Hieu 1 · Shuang-Qing Li 2 · Yang Yu 2 · Ngo Xuan Thanh 3 · Le Tien Dung 3 · Vu Le Tu 3 · Wolfgang Siebel 4 · Fukun Chen 2 Received: 16 May 2015 / Accepted: 3 May 2016 © Springer-Verlag Berlin Heidelberg 2016 Introduction The Song Ma zone in NW Vietnam is interpreted as part of the suture zone between the South China and Indochina blocks (Metcalfe 2006; Jian et al. 2009a, b; Liu et al. 2012). Numerous investigations have been carried out on the evo- lution of this zone, but the time when it formed is still poorly constrained. Different time periods (Devonian, Car- boniferous, Permo-Triassic) for the amalgamation between the South China and Indochina blocks have been pro- posed (Hutchison 1975; Tri 1979; S ¸ engör and Hsu 1984; Janvier et al. 1997; Thanh et al. 2011; Vuong et al. 2013). Both blocks were affected by multiple magmatic and meta- morphic events and, subsequently, were tectonically over- printed during Tertiary strike-slip displacement along the major Red River fault zone. This fault zone has been con- sidered as most influential zone in the geological evolution of North Vietnam with the large-scale (~600 km) sinistral displacement acting during 27–22 Ma (Chung et al. 1997) which makes the interpretations even more complex. Permian to Triassic magmatism is a prominent feature of NW Vietnam. This magmatism might be interpreted in two ways: (1) as product of Tethyan orogeny, that is, sub- duction of the Paleo-Tethyan Ocean and subsequent colli- sion between the Indochina and South China blocks (e.g., Lan et al. 2000; Hoa et al. 2008a, b; Hieu et al. 2013), or (2) as result of major strike-slip tectonics during collision between the Indochina-South China block and the Qiang- tang-Sibumasu block (e.g., Carter et al. 2001; Carter and Clift 2008). In addition, mafic magmatism associated with the late Middle Permian (∼260 Ma) Emeishan large igne- ous province has also been identified in NW Vietnam (Hoa et al. 2008b; Anh et al. 2011). The complex relation between plate tectonic setting and magmatism of NW Vietnam requires a high precision Abstract The Song Ma zone in NW Vietnam bears impor- tant tectonic implications as a potential subduction cor- ridor between the Indochina and South China blocks. On the basis of U–Pb ages, the Hf isotopic characteristics of zircons and the geochemical composition of granitoids, a two-stage magmatic evolution process of the Song Ma zone at ~290–260 and ~245–230 Ma can be proposed. Isotopic analyses indicate magmatic contributions from Neoprote- rozoic oceanic island basalt, Proterozoic continental crust, and depleted mantle or juvenile lithosphere. By combining geochronological and geochemical data from the granitoid rocks, we suggest that the staged magmatic processes of Song Ma zone may be related to a long-lasting period of ocean subduction (ca. 290–260 Ma) and subsequent syn-/ post-collisional evolution (ca. 245–230 Ma). Keywords Vietnam · Song Ma suture · Tethyan belt · Granitoid · Zircon age Electronic supplementary material The online version of this article (doi:10.1007/s00531-016-1337-9) contains supplementary material, which is available to authorized users. * Shuang-Qing Li lsq@mail.ustc.edu.cn 1 University of Science VNU-HCM, 227 Nguyen Van Cu Street, Ho Chi Minh, Vietnam 2 School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China 3 Department of Geology, University of Mining and Geology, Hanoi, Vietnam 4 Department of Earth and Environmental Sciences, Albert- Ludwigs University Freiburg, 79104 Freiburg, Germany