Onset timing of left-lateral movement along the Ailao Shan–Red River Shear Zone: 40Ar/39Ar dating constraint from the Nam Dinh Area, northeastern Vietnam

Abstract

Left-lateral motion along the Ailao Shan±Red River (ASRR) Shear Zone has been widely advocated to be the result of the collision between the Indian and Eurasian plates and to account for sea-¯oor spreading in the South China Sea. Our new 40 Ar/ 39 Ar data on the south-easternmost outcrop of the Day Nui Con Voi metamorphic massif, northern Vietnam, suggest that the exhumation of metamorphic massif by shearing along the ASRR zone began H27 Ma and lasted until H22 Ma. A perfect correlation between location and cooling path for the samples along the shear zone suggests that the transtensional deformation may have propagated northwestward at a rate of H6 cm y À1. Such a good correlation also indicates that the onset of the leftlateral movement of the shear zone may have occurred later than H27.5 Ma. This conclusion is consistent with our previous interpretation that collision-induced southeastward extrusion of Indochina along the ASRR Shear Zone postdates the opening of the South China Sea, and that extrusion tectonics in SE China may not be responsible for the opening of the South China Sea. #

Internal deformation of the Shan-Thai block inferred from paleomagnetism of Jurassic sedimentary rocks in Northern Thailand

“…Shan-Thai block is expected to have started at about 35 Ma and continues today (Lacassin et al, 1996(Lacassin et al, , 1997Holt et al, 2000;Chen et al, 2000;Wang et al, 2000;Flesch et al, 2001;Leloup et al, 2001;Wang et al, 2001). We interpret the localized clockwise rotation in the cenrtral region as a contemporaneous phenomenon with the southward displacement of the Shan-Thai block after it experienced a coherent whole block rotation by about 20° (Fig.…”

Exhumation history of the Red River shear zone in northern Vietnam: New insights from zircon and apatite fission-track analysis

“…21 Ma (e.g. Harrison et al, 1996;Wang et al, 1998;Wang et al, 2000;Leloup et al, 2001;Garnier et al, 2002). These ages suggest a rather prolonged cooling of the DNCV during Oligo-Miocene times.…”

Assessment of Geomorphic Processes and Active Tectonics in Con Voi Mountain Range Area (Northern Vietnam) Using the Hypsometric Curve Analysis Method

“…However, some points are not consistent and disputed (e.g. Tran et al, 1999;Le, 2003;Le et al, 2001;Phan et al, 2004;Wang et al, 2000;. Studies of tectonics in this area have not paid much attention to the role and significance of geomorphology; especially, the lack of quantitative analyses of landscapes using various geomorphic indices.…”