Southeastern extension of the Red River fault zone (RRFZ) and its tectonic evolution significance in western South China Sea

Abstract

Recent geophysical surveys and basin modeling suggest that the No.1 fault in the Yinggehai basin (YGHB) is the seaward elongation of the Red River fault zone (RRFZ) in the South China Sea (SCS). The RRFZ, which separates the South China and Indochina block, extends first along the Yuedong fault, offshore of Vietnam, and then continues southward and breaks off into two branches: the Lupar fault and the Tinjia fault. The southern extension of the Lupar fault dies out beneath the NW Borneo while the Tinjia fault extends southeast and reaches the Brunei-Sabah area. According to the gravity and geomagnetic data, and the tectonic evolution of the basins, there are different evolution histories between the Wan'an basin (WAB) and the basins in the Nansha block. The Tinjia fault may be the boundary between the Balingian block and the Nansha block. Hence, the line linking the Yuedong fault and the Tinjia fault, which both are continental margin faults and strike-slip ones in the geological evolution histories, constitute the boundary between the Indochina and Nansha block. The Lupar fault, in contrast, is an intraplate fault within the Indochina block. The results provide new hints for reconstructing the tectonic evolution history of the RRFZ and the opening of the SCS, and also a framework for hydrocarbon prospecting in the region.The tectonic evolution features in the western South China Sea (SCS) are directly related to the Tethys tectonic province. The Red River fault zone (RRFZ) comprises a large part of the Tethys tectonic province and is the boundary between the Europe Block and the India-Asia Block [1] . It serves as the contact between the uplift of the Qinghai-Tibet Plateau and the SCS opening. The RRFZ, which is an important dividing line in the geology of the SE Asia, is about 1000 km long in the continent from the Qinghai-Tibet Plateau to northern Vietnam. Many workers [2][3][4][5][6][7][8][9][10][11] have looked into its petrology, geochemistry, metamorphic processes, age dating, and numerical simulation [12] and the structure of the crust and the mantle [13] . The models 840 Science in China: Series D Earth Sciencesproposed by these workers [14 -16] suggest that the RRFZ is a major fault with left-lateral strike-slip motion during the Cenozoic shifting to a right-lateral strike-slip displacement in recent time [17] . The structure feature of the RRFZ in the northwestern part of the SCS is obvious. Rangin et al. [18] calibrated the seismic stratigraphy based on the drill well data along the RRFZ and found two important unconformities. The unconformity at 30 Ma is characterized by a left-lateral strike-slip motion and another one at 5.5Ma shows no signs of post-5.5 Ma right-lateral motion. Sun et al. [19] suggested that the RRFZ was a sinistral strike-slip fault before 5 Ma and an obvious dextral strike-slip fault post 5 Ma, simulating the evolution of the Yinggehai basin (YGHB) on the basis of an analogue with thin-and thick-basal plate models. There is no doubt that the RRFZ extends all the way along the YG...

Crustal Magnetic Anomalies and Geological Structure in the Yunnan Region

“…This phenomenon is likely related to the metamorphic rock belt, with a length of ∼900 km and a width of ∼10∼20 km, formed along the Xuelong Mountain, the Diancang Mountain and the Ailao Mountain near the Red River fault and along the Day Nui Con Voi Mountain in Vietnam (Xu et al, 2003). Previous researchers' results have shown that the Red River fault zone is the divider between the Eurasian and Indian plates, and its eastern side extends into the South China Sea Liu et al, 2006). The characteristic that the magnetic anomalies are relatively weak in the area on the west of the Lijiang-Xiaojinhe fault and the Red River fault and relatively strong in the area on the east supports the speculation that the Tibetan Plateau and Yangtze blocks are divided by these two fault zones (Zhong et al, 2005).…”

The Wan-An Fault and its Relationship with the Wan-An Basin, Western South China Sea

“…The collision between the Indian plate and Eurasian plate led to the extrusion of Indo-China and formed a seires of strike-slip faults and basins (eg, Yinggehai Basin, Zhongjiannan Basin, Wanan basin). However, other scientists have argued that the basins in the western South China Sea don't match the escape structure model (Liu et al 2004;Liu et al 2006;Clift et al 2008;Zhu et al 2009). Therefore, the mechanism of the Wan-An Basin need to be redefined.…”

“…The center of Yao, 1996;Wu et al 2006;Liu et al 2006) the basin is thicker than the edge. The depocenter moved eastward significantly, and developed shallow -bathyal facies.…”

Controlling factors on the submarine canyon system: A case study of the Central Canyon System in the Qiongdongnan Basin, northern South China Sea

“…This section focused on the effects of tectonic activity of the RRF on the sedimentary process at about 5.7 Ma. As the boundary of the Eurasian plate and the Indo-Australian plate, the evolution of the RRF showed direct relationships with the uplift of the Tibet Plateau and the expansion of the South China Sea (Liu et al, 2006). Previous studies proposed that the RRF shifted sinistrally during 11.6-5.7 Ma caused by the wedging of the Indian plate into the Eurasian plate and the extrusion of South China Block, whereas, with the further SE movement of the South China Block, from 5.7 Ma to present, the RRF shifted from sinistral to dextral (Allen et al, 1984;Rangin et al, 1995).…”