Tectonic deformation around the eastern Himalayan syntaxis: constraints from the Cretaceous palaeomagnetic data of the Shan-Thai Block

• DOI: 10.1111/j.1365-246x.2008.03885.x
• Publication Date: 2008-10-08T19:13:33Z
• Authors: Kenji Tanaka; Chuanlong Mu; Ken Sato; Kazuhiro Takemoto; Daisuke Miura; Yuyan Liu; Haider Zaman; Zhenyu Yang; Masahiko Yokoyama; Hisanori Iwamoto; Koji Uno; Yo-ichiro Otofuji
• Keywords: Clockwise

Lower to Middle Cretaceous red sandstones were sampled at four localities in the Lanpin-Simao fold belt of Shan-Thai Block describe its regional deformational features. Most samples revealed a characteristic remanent magnetization with unblocking temperatures around 680 °C. Primary natures are ascertained through positive test. A tilt-corrected formation-mean direction for Jingdong (24.5°N, 100.8°E) locality, which is located distance 25 km from Ailaoshan–Red River Fault, northerly declination steep inclination (Dec./Inc. = 8.3°/48.8°, α95 7.7°, N 13). However, mean directions obtained Zhengyuan (24.0°N, 101.1°E), West 101.1°E) and South Mengla (21.4°N, 101.6°E) indicate an easterly deflection declination; such as Dec./Inc. 61.8°/46.1°, 8.1° (N 7), 324.2°/−49.4°, 6.4° 4) 51.2°/46.4°, 5.6° 13), respectively. The palaeomagnetic these incorporated into database Block. When combined geological, geochronological GPS data, processes deformation described follows: Subsequent rigid block clockwise rotation about 20° early stage India–Asia collision, experienced coherent but southward displacement along Red Fault prior 32 Ma. This was then subjected north–south compressive stresses during 32–27 Ma period, played key role shaping structure Chongshan-Lancang-Chiang Mai Belt. Following this some local rotational motion has occurred Pliocene-Quaternary time central part result internal movements reactivated network faults.