Strike–slip ductile shear zones in Thailand

Quantitative finite strain analysis of the quartz mylonites within the Three Pagodas shear zone, western Thailand

“…3d, f) are observed in the biotite gneisses. Isolated s-type clasts of K-feldspar with a clear stair stepping geometry are frequently observed in the orthogneisses (Kanjanapayont, 2015). In some layers of the calc-silicates, the sinistral shear sense is recorded by asymmetric folds (Fig.…”

“…The mylonites of the NW-SE striking Three Pagodas shear zone is 250 km long and 25 km wide and extends from the Three Pagodas Pass on Thai-Myanmar border towards central Thailand (Kanjanapayont, 2015). This ductile strike-slip shear zone cuts the sedimentary units of the Palaeozoic (Silurian-Permian) and Mesozoic sedimentary units, and subordinate low-metamorphic units of Cambrian-Ordovician (Department of Mineral Resources, 1982).…”

“…In Thailand, the main strike-slip structures are the NW-SE sinistral Mae Ping and Three Pagodas shear zones in the west, and the NE-SW dextral Ranong and Khlong Marui shear zones in the south, respectively (Kanjanapayont et al, 2012a;Kanjanapayont, 2015). The Mae Ping and Three Pagodas shear zone with the generally sinistral strike-slip kinematics possible splays out from the Sagaing fault in Myanmar.…”

“…In southern Thailand, the Ranong and Khlong Marui shear zones extend from the continental margin and Mergui basin to the Gulf of Thailand (Tapponnier et al, 1986;Lacassin et al, 1997;Charusiri et al, 2002). All of the major strike-slip shear zones in Thailand possibly were active during the Eocene (Lacassin et al, 1997;Watkinson et al, 2011;Kanjanapayont, 2015;Kanjanapayont et al, 2012b;Nantasin et al, 2012;Palin et al, 2013). Moreover, the high-grade metamorphic and plutonic exposures in such crustal scale strike-slip zones represent an important source for investigating the kinematics and the timing of the tectonic evolution of SE Asia (e.g.…”

“…Lacassin et al, 1997;Palin et al, 2013). Especially in Thailand, syndeformational metamorphic rocks are exposed along the main ductile strike-slip shear zones (Lacassin et al, 1997;Kanjanapayont, 2015;Kanjanapayont et al, 2012a;Nantasin et al, 2012;Palin et al, 2013;Ponmanee et al, 2016) (Fig. 1).…”