Tectonic unit divisions based on block tectonics theory in the South China Sea and its adjacent areas

Identifying distinct tectonic units is key to understanding the geotectonic framework and distribution law of oil and gas resources.The South China Sea and its adjacent areas have undergone complex tectonic evolution processes,and the division of tectonic units is controversial.Guided by block tectonics theory,this study divide the South China Sea and its adjacent areas into several distinguished tectonic units relying on known boundary markers such as sutures(ophiolite belts),subduction-collision zones,orogenic belts,and deep faults.This work suggests that the study area is occupied by nine stable blocks(West Burma Block,Sibumasu Block,LanpingSimao Block,Indochina Block,Yangtze Block,Cathaysian Block,Qiongnan Block,Nansha Block,and Northwest Sulu Block),two suture zones(Majiang suture zone and Southeast Yangtze suture zone),two accretionary zones(Sarawak-Sulu accretionary zone and East Sulawesi accretionary zone),one subduction-collision zone(RakhineJava-Timor subduction-collision zone),one ramp zone(Philippine islands ramp zone),and six small oceanic marginal sea basins(South China Sea Basin,Sulu Sea Basin,Sulawesi Sea Basin,Banda Sea Basin,Makassar Basin,and Andaman Sea Basin).This division reflects the tectonic activities,crustal structural properties,and evolutionary records of each evaluated tectonic unit.It is of great theoretical and practical importance to understand the tectonic framework to support the exploration of oil and gas resources in the South China Sea and its adjacent areas.

Numerical investigation on the flow characteristics of a reverse-polarity plasma torch by two-temperature thermal non-equilibrium modelling

A two-temperature(2 T)thermal non-equilibrium model is developed to address the thermal nonequilibrium phenomenon that inevitably exists in the reverse-polarity plasma torch(RPT)and applied to numerically investigate the plasma flow characteristics inside and outside the RPT.Then,a detailed comparison of the results of the 2 T model with those of the local thermal equilibrium(LTE)model is presented.Furthermore,the temperature of the plasma jet generated by a RPT and the RPT’s voltage are experimentally measured to compare and validate the result obtained by different models.The differences of the measured excitation temperature and the arc voltage between the 2 T model and experimental measurement are less than 13%and 8%,respectively,in all operating cases,validating the effectiveness of the 2 T model.The LTE model overestimates the velocity and temperature distribution of the RPT and its plasma jet,showing that thermal non-equilibrium phenomena cannot be neglected in the numerical modelling of the RPT.Unlike other common hot cathode plasma torches,the thermal non-equilibrium phenomenon is found even in the arc core of the RPT,due to the strong cooling effect caused by the big gas flow rate.