Geometry and 3D seismic characterisation of post-rift normal faults in the Pearl River Mouth Basin,northern South China Sea

Based on high-resolution 3D seismic data acquired in the Pearl(Zhujiang)River Mouth Basin of the northern South China Sea,this study investigated the geometry,spatial extension,and throw distribution of the post-rift normal fault through detailed seismic interpretation and fault modeling.A total of 289 post-rift normal faults were identified in the study area and can be classified into four types:(1)isolated normal faults above the carbonate platform;(2)isolated normal faults cutting through the carbonate platform;(3)conjugate normal faults,and(4)connecting normal faults.Throw distribution analysis on the fault planes show that the vertical throw profiles of most normal fault exhibit flat-topped profiles.Isolated normal faults above the carbonate platform exhibit roughly concentric ellipses with maximum throw zones in the central section whereas the normal faults cutting through the carbonate platform miss the lowermost section due to the chaotic seismic reflections in the interior of the carbonate platform.The vertical throws of conjugate normal faults anomalously decrease toward their intersection region on the fault plane whereas the connecting normal faults present two maximum throw zones in the central section of the fault plane.According to the symmetric elliptical distribution model of fault throw,an estimation was made indicating that normal faults cutting through the carbonate platform extended downward between-1308 s and-1780 s(two-way travel time)in depth and may not penetrate the entire Liuhua carbonate platform.Moreover,it is observed that the distribution of karst caves on the top of the carbonate platform disaccord with those of hydrocarbon reservoirs and the post-rift normal faults cutting through the carbonate platform in the study area.We propose that these karst caves formed most probably by corrosive fluids derived from magmatic activities during the Dongsha event,rather than pore waters or hydrocarbons.

Facies character and geochemical signature in the late Quaternary meteoric diagenetic carbonate succession at the Xisha Islands,South China Sea

The late Quaternary shallow-water carbonates have been altered by a variety of diagenetic processes,and further influenced by high-amplitude global and regional sea level changes.This study utilizes a new borehole drilled on the Yongxing Island,Xisha Islands to investigate meteoric diagenetic alteration in the late Quaternary shallowwater carbonates.Petrographic,mineralogical,stable isotopic and elemental data provide new insights into the meteoric diagenetic processes of the reef limestone.The results show the variation in the distribution of aragonite,high-Mg calcite(HMC)and low-Mg calcite(LMC)divides the shallow-water carbonates in Core SSZK1 into three intervals,which are UnitⅠ(31.20-55.92 m,LMC),UnitⅡ(18.39-31.20 m,aragonite and LMC)and UnitⅢ(upper 18.39 m of core,aragonite,LMC and HMC).Various degrees of meteoric diagenesis exist in the identified three units.The lowermost UnitⅠhas suffered almost complete freshwater diagenesis,whereas the overlying UnitsⅡandⅢhave undergone incompletely meteoric diagenesis.The amount of time that limestone has been in the freshwater diagenetic environment has the largest impact on the degree of meteoric diagenesis.Approximately four intact facies/water depth cycles are recognized.The cumulative depletion of elements such as strontium(Sr),sodium(Na)and sulphur(S)caused by duplicated meteoric diagenesis in the older reef sequences are distinguished from the younger reef sequences.This study provides a new record of meteoric diagenesis,which is well reflected by whole-rock mineralogy and geochemistry.

Pharmacological manipulation of macrophage autophagy effectively rejuvenates the regenerative potential of biodegrading vascular graft in aging body

Declined regenerative potential and aggravated inflammation upon aging create an inappropriate environment for arterial regeneration.Macrophages are one of vital effector cells in the immune microenvironment,especially during biomaterials mediated repairing process.Here,we revealed that the macrophage autophagy decreased with aging,which led to aggravated inflammation,thereby causing poor vascular remodeling of artificial grafts in aging body.Through loading the autophagy-targeted drugs,rapamycin and 3-MA(3-methyladenine),in PCL(polycaprolactone)sheath of the PGS(poly glycerol sebacate)-PCL vascular graft,the essential role of macrophage autophagy was confirmed in regulating macrophage polarization and biomaterial degradation.Moreover,the utilization of rapamycin promoted anti-inflammatory polarization of macrophage by activating autophagy,which further promoted myogenic differentiation of vascular progenitor cells and accelerated endothelialization.Our study elucidated the contribution of pharmacological manipulation of macrophage autophagy in promoting regeneration of small caliber artery,which may pave a new avenue for clinical translation of vascular grafts in aging body.

The Arab League’s Decision-making System and Arab Integration

This paper analyzes the function of the Arab League decision-making system and its influences on the Arab integration from the perspective of institutionalism and integration theory.Arab League makes its decisions on the basis of cooperation and negotiations.Theoretically,only in some policy fields where cooperation outperforms unilateral action,can such a decision institution lead to mutual policies and unanimous actions.However,practically,this system lacks efficient operations on the regional level.Even in the fields of economy or security,where member states share more mutual interests,the integrative cooperation of the Arab League is confined to the limited policy framework,with minimum agreements as its outcome.Experience from the Europe Union suggests that there must be a supra-national institution to propose draft,supervise the development and implementation of the policies,and regulate the behaviors of relevant nations.The integrative direction and outlook of Arab League depends exactly on its future decision-making system.