Horsetailing is an important feature to identify the strike-slip structure and indicates the movement mode of the fault.However,the formation mechanism of horsetailing in the extensional regime remains unclear.In this study,the formation process of horsetailing is reproduced through physical experiment,simulating the Linnan sag in the extensional regime.The results of the physical experiment demonstrates that the formation of the horsetailing in the extensional regime requires two phases of non-coaxial stretching plus the segment of the principal fault.The stretching distance in the early phase is slightly smaller than that in the middle-late phase.The segment point of the principal fault is only the intersection of the horsetailing structure and the principal fault.The horsetailing formed in the extensional regime is different from that in the strike-slip regime.For the formation of structure,the principal fault is dip-slip in the early phase and then becomes an oblique-slip in the middle-late phase,and the horsetailing is composed of the middle-late new tensile faults.The fault properties of the horsetailing in the extensional regime has important guiding significance for the longitudinal fluid migration along the fault in petroliferous basins.
Extensional fracturing often occurs in hard rock masses during excavation at depths,for example,>1000 m below the ground surface.Surface-parallel fractures are created in the surrounding rock mass,which is typically subjected to stresses parallel to the free rock surfaces after excavation.These are called extensional fractures because the strains perpendicular to the fracture planes are extensional and the opposite surfaces of each fracture tend to separate from each other as soon as the fracture is created.These fractures predominantly propagate parallel to the maximum principal stressσ1 in the surrounding rock mass.This study analyses extensional fractures observed during excavations in cut-and-fill mining stopes in a deep metal mine.This analysis explores the process of extensional fracturing during excavation in an undisturbed rock mass.In general,intensive spalling occurred on the roof surfaces immediately after the excavation of the undisturbed rock mass.This spalling terminated after a certain depth of rock failure,while burst sounds intermediately emitted from the surrounding rock mass,indicating that rock fracturing was ongoing at depth.In the subsequent cutting slices,the spacing between the extensional fractures decreased with increasing mine-out space in the stope.An extensional fracturing criterion was proposed based on microscopic observations of microcrack development in the rock in response to applied stress.The crack initiation and extensional fracturing processes are associated with two critical extensional strains which are related to the secondary stress state in the position.In areas close to the free rock surface whereσ3=0,the stress for crack initiation is(σ1+σ2)=0.4σc,whereas the stress for extensional fracturing is(σ1+σ2)=0.8σc.
This work presents a novel radio frequency(RF)narrowband Si micro-electro-mechanical systems(MEMS)filter based on capacitively transduced slotted width extensional mode(WEM)resonators.The flexibility of the plate leads to multiple modes near the target frequency.The high Q-factor resonators of around 100000 enable narrow bandwidth filters with small size and simplified design.The 1-wavelength and 2-wavelength WEMs were first developed as a pair of coupled modes to form a passband.To reduce bandwidth,two plates are coupled with aλ-length coupling beam.The 79.69 MHz coupled plate filter(CPF)achieved a narrow bandwidth of 8.8 kHz,corresponding to a tiny 0.011%.The CPF exhibits an impressive 34.84 dB stopband rejection and 7.82 dB insertion loss with near-zero passband ripple.In summary,the RF MEMS filter presented in this work shows promising potential for application in RF transceiver front-ends.
Wei WangWenli LiuJunyuan ZhaoBo NiuZeyu WuYinfang ZhuJinling YangFuhua Yang
The Weber Deep represents a widespread crustal extension system in eastern Indonesia with a huge submarine normal fault system,the Banda Detachment,related to the slab rollback tectonic model(Spakman and Hall,2010;Cummins et al.,2020).However,the cause of tectonic extension remains debated(e.g.,Audley-Charles et al.,1972;McCaffrey,1988;Das,2004;Spakman and Hall,2010;Pownall et al.,2013;Cummins et al.,2020;Hutchings and Mooney,2021;Shah et al.,2023).
Afroz Ahmad SHAHMuhammad Gazali RACHMANAshar Muda LUBIS
The Sonid Zuoqi ductile detachment zone is located at the southeastern margin of the Central Asian orogenic belt(CAOB),striking EW and dipping to the S.The major rock type of the Sonid Zuoqi ductile detachment zone is mylonite derived from granite.The sequence of mylonite features is:(1)S and C foliations of mylonite,and(2)extensional crenulation cleavage(ecc)or C′and the kinematic vorticity(Wk)value changed from 0.70 to 0.95 and from 0.37 to 0.69,respectively;the strain type of the mylonites within the Sonid Zuoqi ductile detachment zone is compressional to planar strain.The strong deformation mylonite and Halatu plutons yielded a zircon U-Pb age of 244 Ma and a zircon(U-Th)/He age of 214 Ma,respectively.Based on the strain and kinematic vorticity analysis,together with the zircon U-Pb and zircon(U-Th)/He ages and the regional tectonic background,the study area experienced three stage evolution:tangential simpleshear(244 Ma),simple-shear-dominated general shear represented by upper crustal extension(224 Ma)and pure-shear-dominated general shear represented by the Halatu pluton doming(214 Ma),which constrained the early Mesozoic NE-SW crustal extension at the southeastern margin of the CAOB.This NE-SW extension probably originated from the postorogenic extensional collapse of the CAOB,subsequent exhumation being controlled by the far afield effects of the closure of the Mongol-Okhotsk belt.
