Abstract
It is of great significance to construct a three-dimensional underground velocity model for the study of geodynamics and tectonic evolution. Southeast Asia has attracted much attention due to its complex structural features. In this paper, we collected relative travel time residuals data for 394 stations distributed in Southeast Asia from 2006 to 2019, and 14,011 seismic events were obtained. Then, teleseismic tomography was applied by using relative travel time residuals data to invert the velocity where the fast marching method (FMM) and subspace method were used for every iteration. A novel 3D P-wave velocity model beneath Southeast Asia down to 720 km was obtained using this approach. The tomographic results suggest that the southeastern Tibetan Plateau, the Philippines, Sumatra, and Java, and the deep part of Borneo exhibit high velocity anomalies, while low velocity anomalies were found in the deep part of the South China Sea (SCS) basin and in the shallow part of Borneo and areas near the subduction zone. High velocity anomalies can be correlated to subduction plates and stable land masses, while low velocity anomalies can be correlated to island arcs and upwelling of mantle material caused by subduction plates. We found a southward subducting high velocity body in the Nansha Trough, which was presumed to be a remnant of the subduction of the Dangerous Grounds into Borneo. It is further inferred that the Nansha Trough and the Dangerous Grounds belong to the same tectonic unit. According to the tomographic images, a high velocity body is located in the deep underground of Indochina–Natuna Island–Borneo–Palawan, depth range from 240 km to 660 km. The location of the high velocity body is consistent with the distribution range of the ophiolite belt, so we speculate that the high velocity body is the remnant of thee Proto-South China Sea (PSCS) and Paleo-Tethys. This paper conjectures that the PSCS was the southern branch of Paleo-Tethys and the gateway between Paleo-Tethys and the Paleo-Pacific Ocean. Due to the squeeze of the Australian plate, PSCS closed from west to east in a scissor style, and was eventually extinct under Borneo.
Highlights
The Proto-South China Sea (PSCS) refers to the ocean that was once located in the southeastern part of China in the area where the South China Sea (SCS) stands [1,2,3,4]
Cretaceous based on deep-sea radiolarians in the serpentine suite of the Natuna–Kalimantan–Palawan distribution, and that it may be a back-arc sea formed by subduction of the Pacific plate [13]; Metcalfe argued that the PSCS was formed when the Cretaceous East Asian continental margins pulled apart by studying the tectonic shelf of the Epiphytic Sundaland [14]; Lu studied the influence of Tethys and Paleo-Pacific on the PSCS through regional geological, paleontological, gravity, and magnetic anomalies [15]; numerous scholars have determined the existence of the PSCS from 70 Ma to
The three-dimensional velocity model obtained in this paper can provide more evidence for studying the tectonic evolution of the PSCS
Summary
The Proto-South China Sea (PSCS) refers to the ocean that was once located in the southeastern part of China in the area where the South China Sea (SCS) stands [1,2,3,4]. Relative travel time residuals data from 2006 to 2019 were collected for 394 stations in the study area. The final collection was 14,011 seismic events recorded from 394 seismic stations in the study area, and 180,225 useful P-wave relative travel time residuals were obtained for inversion. The process of picking up relative travel time residuals based on the above method is shown in Figure 3 [39]. We used the adaptive stacking (astack) method [40] and multi-channel cross correlation (MCC) method [36] to superimpose the waveform data, and compared the difference between the residuals obtained by the two Remote Sens. 5S0p]l.inSeppliansesipnagssthinrgoutghhronuogdhe nvoadlueesvaislueessseinstieaslsfeonrtitarladfoitriotnraadl ictuiobnicalspculinbiecinsptelrinpeolianttieornp. oTlahteiofonr.mThoef fionrtemrpooflianttioernpfoulnatcitoionnfucnucbtiicoBn-csupbliinceBs-uspselidneins uthsiesdpianptehriswpaaspseirmwilaasr stoimEiqlaurattoioEnq(u1a).tiTohni(s1w). aTshlioscwalalys lsoucpaplloyrsteudppanordteddidanndotdniedcnesostanrielcyepssaasrsiltyhrpoausgshthtrhoeungohdtehveanloudese. values
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
