Knowing the phase relations of carbon-bearing phases at high-pressure(HP) and high-temperature(HT) condition is essential for understanding the deep carbon cycle in the subduction zones.In particular,the phase relatio...Knowing the phase relations of carbon-bearing phases at high-pressure(HP) and high-temperature(HT) condition is essential for understanding the deep carbon cycle in the subduction zones.In particular,the phase relation of carbon-bearing phases is also strongly influenced by redox condition of subduction zones,which is poorly explored.Here we summarized the phase relations of carbon-bearing phases(calcite,aragonite,dolomite,magnesite,graphite,hydrocarbon) in HP metamorphic rocks(marble,metapelite,eclogite) from the Western Tianshan subduction zone and high-pressure experiments.During prograde progress of subduction,carbonates in altered oceanic crust change from Ca-carbonate(calcite) to Ca,Mg-carbonate(dolomite),then finally to Mgcarbonate(magnesite) via Mg-Ca cation exchange reaction between silicate and carbonate,while calcite in sedimentary calcareous ooze on oceanic crust directly transfers to high-pressure aragonite in marble or amorphous CaCO3 in subduction zones.Redox evolution also plays a significant effect on the carbon speciation in the Western Tianshan subduction zone.The prograde oxygen fugacity of the Western Tianshan subduction zone was constrained by mineral assemblage of garnet-omphacite from FMQ-1.9 to FMQ-2.5 at its metamorphic peak(maximum P-T) conditions.In comparison with redox conditions of other subduction zones,Western Tianshan has the lowest oxygen fugacity.Graphite and light hydrocarbon inclusions were ubiqutously identified in Western Tianshan HP metamorphic rocks and speculated to be formed from reduction of Fe-carbonate at low redox condition,which is also confirmed by high-pressure experimental simulation.Based on petrological observation and high-pressure simulation,a polarized redox model of reducing slab but oxidizing mantle wedge in subduction zone is proposed,and its effect on deep carbon cycle in subduction zones is further discussed.展开更多
A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprob...A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprobe and LA-ICP-MS were employed to quantity some major and trace elements,and unpolarized FTIR spectroscopy was applied to probe the different types of hydrogen defects,explore water-incorporation mechanisms and quantify water contents.Trace amounts of A1 and B were detected in the coesite.Combining our results with the results in the literatures,we have found no positive correlation between the Al contents and the"Al"-based hydrogen concentrations,suggesting that previously proposed hydrogen-incorporation mechanism H^++Al^3+■Si^4+does not function in coesite.In contrast,we have confirmed the positive correlation between the B contents and the B-based hydrogen concentrations.The hydrogen-incorporation mechanism H^++B3^+■Si^4+readily takes place in coesite at different P-T conditions,and significantly increases the water content at both liquid-saturated and liquid-undersaturated conditions.For the SiO2-H2O system,we have found that type-Ⅰhydrogarnet substitution plays a dictating role in incorporating water into coesite at liquid-saturated condition,type-II hydrogarnet substitution contributes significantly at nearly dry condition,and both operate at conditions in between.The water solubility of coesite,as dictated by the type-Ⅰhydrogarnet substitution,positively correlates with both P and T,cH2O=-105(30)+5.2(32)×P+0.112(26)×T,with cH2O in wt ppm,P in GPa and T in℃.Due to its low water solubility and small fraction in subducted slabs,coesite may contribute insignificantly to the vertical water transport in subduction zones.Furthermore,the water solubility of any coesite in exhuming ultra-high pressure metamorphic rocks should be virtually zero as coesite becomes metastable.With an adequately fast waterdiffusion rate,this metastable coesite should be completely dry,which may have been the key factor to the partial preservation of most natural Coe.As a byproduct,a new IR experimental protocol for accurate water determination in optically anisotropic nominally anhydrous minerals has been found.Aided with the empirical method of Paterson(1982)it employs multiple unpolarized IR spectra,collected from randomly-orientated mineral grains,to approximate both total integrated absorbance and total integrated molar absorption coefficient.Its success relies on a high-level orientation randomness in the IR analyses.展开更多
The Chinese Tianshan belt of the southern Altaids has undergone a complicated geological evolution. Different theories have been proposed to explain its evolution and these are still hotly debated. The major subductio...The Chinese Tianshan belt of the southern Altaids has undergone a complicated geological evolution. Different theories have been proposed to explain its evolution and these are still hotly debated. The major subduction polarity and the way of accretion are the main problems. Southward, northward subduction and multiple subduction models have been proposed. This study focuses on the structural geology of two of the main faults in the region, the South Tianshan Fault and the Nikolaev Line. The dip direction in the Muzhaerte valley is southward and lineations all point towards the NW. Two shear sense motions have been observed within both of these fault zones, a sinistral one, and a dextral one, the latter with an age of 236-251 Ma. Structural analyses on the fault zones show that subduction has been northward rather than southward. The two shear sense directions indicate that the Yili block was first dragged along towards the east due to the cloclkwise rotation of the Tarim block. After the Tarim block stopped rotating, the Yili block still kept going eastward, inducing the dextral shear senses within the fault zones.展开更多
The Gejiu-Bozushan-Laojunshan W-Sn polymetallic metallogenic belt(GBLB)in southeast Yunnan Province is an important part of the southwestern Yangtze Block in South China.Tin polymetallic mineralization in this belt in...The Gejiu-Bozushan-Laojunshan W-Sn polymetallic metallogenic belt(GBLB)in southeast Yunnan Province is an important part of the southwestern Yangtze Block in South China.Tin polymetallic mineralization in this belt includes the Niusipo,Malage,Songshujiao,Laochang and Kafang ore fields in the Gejiu area which are spatially and temporally associated with the Kafang-Laochang and Songshujiao granite plutons.These granites are characterized by variable A/CNK values(mostly>1.1,except for two samples with 1.09),high contents of SiO2(74.38-76.84 wt.%)and Al2 O3(12.46-14.05 wt.%)and variable CaO/Na2 O ratios(0.2-0.65)as well as high zirconδ18O values(7.74‰-9.86‰),indicative of S-type affinities.These rocks are depleted in Rb,Th,U,Ti,LREE[(La/Yb)N=1.4-20.51],Ba,Nb,Sr,and Ti and display strong negative Eu and Ba anomalies.The rocks possess high Rb/Sr and Rb/Ba ratios,relatively low initial 87Sr/86Sr ratios(0.6917-0.7101),and less radiogenicεNd(t)values(-8.0 to-9.1).The zircon grains from these rocks show negativeεHf(t)values in the range of-3.7 to-9.9 with mean TDM2(Nd)and TDM2(Hf)values of 1.57 Ga and 1.55 Ga.They show initial 207Pb/204Pb ranging from15.69 to 15.71 and 206Pb/204Pb from 18.36 to 18.70.Monazite from Songshujiao granites exhibits higher U and lower Th/U ratios,lowerδ18O values and higherεHf(t)values than those of the zircon grains in the KafangLaochang granites.The geochemical and isotopic features indicate that the Laochang-Kafang granites originated by partial melting of Mesoproterozoic crustal components including biotite-rich metapelite and metagraywacke,whereas the Songshujiao granites were derived from Mesoproterozoic muscovite-rich metapelite crustal source.Most zircon grains from the Songshujiao,Laochang and Kafang granites have high-U concentrations and their SIMS U-Pb ages show age scatter from 81.6 Ma to 88.6 Ma,80.7 Ma to 86.1 Ma and 82.3 Ma to 87.0 Ma,suggesting formation earlier than the monazite and cassiterite.Monazite SIMS U-Pb ages and Th-Pb ages of three same granite samples are consistent and show yielded 206 Pb/238U ages of 83.7±0.6 Ma,83.7±0.6 Ma,and 83.4±0.6 Ma,and 208Pb/232Th ages of 83.2±0.5 Ma,83.8±0.4 Ma,and 83.5±0.9 Ma,which are within the range of the SIMS zircon U-Pb ages from these rocks.The data constrain the crystallization of the granites at ca.83 Ma.In situ U-Pb dating of two cassiterite samples from the cassiterite-sulfide ore in the Songshujiao ore field and Kafang ore field,and two from the cassiterite-oxide+cassiterite bearing dolomite in the Laochang ore field yielded weighted mean 206 Pb/238U ages of 83.5±0.4 Ma(MSWD=0.6),83.5±0.4 Ma(MSWD=0.5),83.6±0.4 Ma(MSWD=0.6)and 83.2±0.7 Ma(MSWD=0.6),respectively.Combined with geological characteristics,the new geochronological data indicate that the formation of the granites and Sn polymetallic deposits are coeval.We correlate the magmatic and metallogenic event with lithospheric thinning and asthenosphere upwelling in continental extension setting in relation to the eastward subduction of the Neo-Tethys beneath the Sanjiang tectonic domain during Late Cretaceous.展开更多
The purpose of our study was to compare interfractional bony setup variations in pelvic anatomy with two immobilization devices, the patient-specific Vac-Lok and the generic Dual Leg Positioner system (both Civco Medi...The purpose of our study was to compare interfractional bony setup variations in pelvic anatomy with two immobilization devices, the patient-specific Vac-Lok and the generic Dual Leg Positioner system (both Civco Medical Solutions, Kalona, IA), for bilateral proton radiotherapy of the prostate. Two groups of 10 patients were studied. Computed tomography (CT) was performed three times a week, yielding 233 CT image sets for the vacuum system group and 252 for the other group. The translational shifts of the pelvic bone and prostate and rotation of the upper femurs of the femoral heads with respect to the simulation CT images were analyzed. Along the anterior-posterior and lateral axes, mean and systematic translational variations of the pelvic bone and prostate, relative to skin fiducials, were significantly lower in the Vac-Lok group (all p 0.01) than in the Dual Leg Positioner group. Abduction of the upper femur, the dominant rotation, had random rotational variations of 1.9° and 2.0° and systematic rotations of 3.1° and 2.9° for the vacuum and generic system groups, respectively. Femoral abduction was highly correlated with anterior prostate displacement for both femurs in both groups (p tion introduced during simulation CT, particularly with the generic immobilization system. High degrees of femoral rotation may introduce prostate translation and distal misalignment of lateral proton beams with the prostate.展开更多
We proposed the use of a hybrid deformable image registration approach that combines compact-support radial basis functions (CSRBF) spline registration with intensity-based image registration. The proposed method firs...We proposed the use of a hybrid deformable image registration approach that combines compact-support radial basis functions (CSRBF) spline registration with intensity-based image registration. The proposed method first uses the pre-viously developed image intensity-based method to achieve voxel-by-voxel correspondences over the entire image re-gion. Next, for those areas of inaccurate registration, a sparse set of landmark correspondences was defined for local deformable image registration using a multi-step CSRBF approach. This hybrid registration takes advantage of both intensity-based method for automatic processing of entire images and the CSRBF spline method for fine adjustment over specific regions. The goal of using this hybrid registration is to locally control the quality of registration results in specific regions of interest with minimal human intervention. The major applications of this approach in radiation ther-apy are for the corrections of registration failures caused by various imaging artifacts resulting in, low image contrast, and non-correspondence situations where an object may not be imaged in both target and source images. Both synthetic and real patient data have been used to evaluate this hybrid method. We used contours mapping to validate the accuracy of this method on real patient image. Our studies demonstrated that this hybrid method could improve overall registra-tion accuracy with moderate overhead. In addition, we have also shown that the multi-step CSRBF registration proved to be more effective in handling large deformations while maintaining the smoothness of the transformation than origi-nal CSRBF.展开更多
The South China Block(SCB)is among the large-scale W-Sn mineralized regions of the globe.The Laojunshan W-Sn-dominant ore area(LOA)in the western part of the SCB preserves the records of the tectonic history of the Te...The South China Block(SCB)is among the large-scale W-Sn mineralized regions of the globe.The Laojunshan W-Sn-dominant ore area(LOA)in the western part of the SCB preserves the records of the tectonic history of the Tethys realm extending through North Vietnam,and Yangtze to Cathaysia blocks,with coeval formation of giant metallic deposits.The prolonged tectonic activities and their control on the genesis and spatio-temporal distribution of giant metallic deposits in the LOA provide a window for a holistic understanding of the tectono-metallogenesis of the SCB.In this study,we present results from a multi-chronologic study to determine the timing of formation of the cassiterite-wolframite-schee lite mineralization.The results suggest three distinct tectono-metallogenic periods in the LOA during the geodynamic evolution of the surrounding tectonic units.The opening of the Proto-Tethys Ocean between the Yangtze-Indochina blocks and the westward Paleo-Pacific subduction beneath the Cathaysia block(420–380 Ma)jointly contributed to the Silurian to early Devonian intracontinental orogeny in the middle of the SCB that involved top-to-the-north thrusting along NE-striking shear zones.This event generated the Dulong-Song Chay granitoids,together with the formation of Xinzhai Sn deposit related to sheared mylonitic granites(ca.419 Ma)and pegmatites(ca.389 Ma),which include the early-stage Sn-sulfide skarn(ca.418 Ma)and the late-stage Sn-bearing schist(ca.389 Ma).During the Late Permian to Late Triassic(260–220 Ma),with the closure of the Proto-Tethys oceans in the west and ongoing Paleo-Pacific westward subduction in the east,the SCB and Indochina Block(IB)were amalgamated which also marks the time of formation of the Nanwenhe scheelite skarn deposit.The subducted PaleoTethys oceanic crust was likely entrained by the nearby rising Emeishan mantle plume(270–259 Ma),which formed the Maguan diabase(ca.260 Ma)that shows significantly older Re-Os model age of ca.268 Ma,suggesting that the Nanwenhe mineralization is potentially derived from ca.260 Ma source.Furthermore,the intraplate shortening induced thin skinned crustal deformation and low grade metamorphism(ca.230 Ma),with the main stage of scheelite-Sn-Mo mineralization(229.9,229.8 and 219 Ma)and contemporary formation of the pegmatite(230.7 Ma).The Late Cretaceous involved two episodes of alternate extension and shortening,driven by the subduction polarity change from northwestward subduction of the Okhotomorsk block to northward subduction of the NeoTethys seafloor.The evolution of the LOA consists of the NW–SE transpression ending ca.100 Ma,the WNW–ESE extension in the earlier episode lasting from 100 Ma to 86 Ma,the WNW–ESE transpression beginning at ca.85 Ma and the NAS extension in the later episode during the latest Cretaceous,which produced the extension-related three periods of Laojunshan granitic magmatism and coeval Sn-W mineralization,with ages in the range of 90–89 Ma,87–85 Ma and 83–79 Ma.We also evaluate the implications of magmaticmetamorphic-metallogenic degassing on the regional paleoclimatic history.展开更多
Yushugou granulite-peridotite complex,located at the east part of the northern margin of South Tianshan,may represent an ophiolitic slice subducted to 40–50 km depth with high-pressure granulite facies metamorphism.A...Yushugou granulite-peridotite complex,located at the east part of the northern margin of South Tianshan,may represent an ophiolitic slice subducted to 40–50 km depth with high-pressure granulite facies metamorphism.Although a lot of studies have been conducted on rocks in this belt,the rock association and tectonic background of the ophiolitic slice are still in dispute.A detailed study on petrology,phase equilibrium modeling and U-Pb zircon ages have been performed on the metagabbro vein in peridotite unit to constrain the tectonic evolution of the Yushugou granulite-peridotite complex.Three stages of mineral assemblage in the metagabbro were defined as stage I:Cpx^A+Opx^A+Pl^A,which represents the original minerals of the metagabbro vein;stage II:Cpx^B+Opx^B+Pl^B+Spl,which represents the mineral assemblage of granulite facies metamorphism with peak P-T conditions of 4.2–6.9 kbar and 940–1070℃;stage III is characterized by the existence of prehnite,thomsonite and amphibole in the matrix,indicating that the metagabbro vein may be influenced by fluids during retrograde metamorphism.Combined with the crosscut relationship,it can be deduced that the metagabbro vein,together with the peridotite in Yushugou granulite-peridotite complex has experienced similar high-temperature granulite facies metamorphism.The zircon chronological data shows that the protolith age of the metagabbro vein is 400.5±6.2 Ma,reflecting Devonian magmatism event and the granulite facies metamorphism occurred at^270 Ma which may be related to the post-collisional magmatism.展开更多
Pelitic granulite from the Khondalite Belt,North China Craton,is composed of garnet,sillimanite,perthite,biotite and quartz.Oriented rutile needles in garnet are reported for the first time from the granulite.The ruti...Pelitic granulite from the Khondalite Belt,North China Craton,is composed of garnet,sillimanite,perthite,biotite and quartz.Oriented rutile needles in garnet are reported for the first time from the granulite.The rutile needles have been identified by optical microscopy and confirmed by in situ Raman spectroscopy,where they show the characteristic bands at 446–448 and 610 cm-1.Because of their very strong shape preferred orientation in3–4 easily observable directions,these rutile needles are interpreted to have formed by precipitation during exhumation and cooling following peak metamorphism.The ternary feldspar geothermometer gives a peak metamorphic temperature of*980°C at 10 kbar.The presence of oriented rutile needles in garnet is suggested to be a valuable indicator of ultrahigh-temperature(UHT)metamorphism in the Khondalite Belt and therefore likely in other UHT terrains.展开更多
Geochronological investigation on gneisses of granitic to leucogranitic compositions in Cuona,south Tibet,reveal that their protoliths formed at 808.8 ± 7.9-816.4 ± 3.4 Ma and 855.8 ± 7.0 Ma,respectivel...Geochronological investigation on gneisses of granitic to leucogranitic compositions in Cuona,south Tibet,reveal that their protoliths formed at 808.8 ± 7.9-816.4 ± 3.4 Ma and 855.8 ± 7.0 Ma,respectively.Zircon rims from the granitic gneiss record a metamorphic age of 739.4 ± 4.3 Ma.Lu-Hf isotopic analyses on zircon grains with Neoproterozoic ages yield negative ε_(Hf)(t) values from-9.0 to-4.2,and the corresponding two-stage Hf model ages are 1965-2228 Ma.Whole-rock geochemical data indicate that all granitic gneisses are K-riched calc-alkali series.These new data together with literature data show that(1) the Himalayan terrane experienced an episode of Neoproterozoic magmatism at 850-800 Ma;(2) the Neoproterozoic magma of granitic compositions were derived from partial melting of ancient crusts,possibly due to the thermal perturbation related with the breakup of the Rodinia supercontinent.展开更多
The sediments,including calcareous,siliciclastic and volcanoclastic,usually occupy>90%in volume of an accretionary complex and thus,if involved in subduction zones,their maximum return depths(i.e.,peak pressures)ar...The sediments,including calcareous,siliciclastic and volcanoclastic,usually occupy>90%in volume of an accretionary complex and thus,if involved in subduction zones,their maximum return depths(i.e.,peak pressures)are fundamental to unravel the geodynamic processes during the convergence of plates[1].As a unique example of accreted complex returned from sub-arc depths(>90 km)worldwide.展开更多
A newly developed microprobe-based methodology(the Flank Method)for Fe^(3+)/RFe quantification has been successfully applied to some natural garnets from the North Qilian eclogites by JEOL JXA-8100microprobe at Peking...A newly developed microprobe-based methodology(the Flank Method)for Fe^(3+)/RFe quantification has been successfully applied to some natural garnets from the North Qilian eclogites by JEOL JXA-8100microprobe at Peking University.The results demonstrated an obvious discrepancy in comparison with the outcomes by conventional stoichiometric calculations.This methodology allows to measure theFe^(3+)/Rmeasurement of Fe^(3+)According to the compositional zonation displayed in the studied eclogitic garnets from North Qilian,a prograde metamorphic°C to 22 kbar,600°C was reconstructed.More interestingly,the measured Fe^(3+)/RFe ratios in garnets decreasing from core to rim may probably imply that the oxygen fugacity(f O_2)declines with the depth of the subduction zone.展开更多
The features of carrier-based aircraft’s navigation systems during the approach and landing phases are investigated.A new adaptive Kalman filter with unknown state noise statistics is proposed to improve the accuracy...The features of carrier-based aircraft’s navigation systems during the approach and landing phases are investigated.A new adaptive Kalman filter with unknown state noise statistics is proposed to improve the accuracy of the INS/GNSS integrated navigation system.The adaptive filtering algorithm aims to estimate and adapt the unknown state noise covariance Q in high dynamic conditions,when the measurement noise covariance R is assumed to be known empirically in advance.The new adaptive Kalman filter based on the innovation sequence and pseudo-measurement vector approach makes it more effective to estimate and adapt Q.The simulation results and semi-physical experiments show that the application of the proposed adaptive Kalman filter can guarantee a higher estimation accuracy of the state variables.展开更多
Ophiolites play a key role in understanding subduction-accretion-collision processes. Herein, we discuss origin and metamorphic evolution of an enigmatic, Neoproterozoic ophiolite candidate—the mafic-ultramafic Songs...Ophiolites play a key role in understanding subduction-accretion-collision processes. Herein, we discuss origin and metamorphic evolution of an enigmatic, Neoproterozoic ophiolite candidate—the mafic-ultramafic Songshugou Complex, Qinling belt, China—summarizing published thermobarometr);U/Pb geochronology, and geochemistry and presenting new phase equilibrium modeling. Garnet, rarely preserved in amphibolites of the Songshugou Complex, has prograde zoning and low-pvrope cores |Alm54-71(Grs+And)25-30PrP1-6Sps5-12. It formed at quartz eclogite facies conditions of 1.93-2.54 GPa, 462-542℃. During exhumation, garnet first was mantled by plagioclase-rich coronas at about 0.7-1.2 GPa, 660-710℃. During an isothermal uplift to 0.5-0.8 GPa, these coronas evolved widely into n-shaped aggregates and eventually into whitish ribbons oriented with a steeply southwest dipping mineral stretching lineation. The exhumation into middle-upper crustal levels proceeded till the Late Devonian. The oceanic protoliths of the eclogites were emplaced into continental crust in the Neoproterozoic and dragged into a subduction zone in North Qinling in the Cambrian. The ultramafic rocks of the Songshugou Complex were not subducted with the mafic rocks in a coherent block given the absence of garnet but ubiquitous occurrence of spinel implies a P maximum of ?1.7 GPa. Rather, mafic and ultramafic rocks belonged to downgoing and overriding plate, respectively. They were juxtaposed at 0.8-1.7 GPa at Early Ordovician time.展开更多
The first Archean eclogite was announced from the Salma and Gridino complexes of Belomorian Province(Russia)in Fennoscandian Shield(Fig.1a)[1]that has aroused quite a resonance worldwide from all aspects;the debates o...The first Archean eclogite was announced from the Salma and Gridino complexes of Belomorian Province(Russia)in Fennoscandian Shield(Fig.1a)[1]that has aroused quite a resonance worldwide from all aspects;the debates on the actual age of the Belomorian eclogites have never stopped ever since and in all there are three scenarios are suggested(1)one time in Mesoarchean,(2)two times in Neoarchean and Paleoproterozoic and(3)one time展开更多
In terms of petrology,thermomechanical simulation is an important frontier to study the geodynamic process of the exhumation and uplift of high pressure(HP)to ultrahigh pressure(UHP)metamorphic rocks in subduction zon...In terms of petrology,thermomechanical simulation is an important frontier to study the geodynamic process of the exhumation and uplift of high pressure(HP)to ultrahigh pressure(UHP)metamorphic rocks in subduction zones and collision orogenic belts.Based on the recent petrological studies and numerical modellings for the exhumation of HP to UHP metamorphic terranes,the exhumation mechanisms of HP to UHP metamorphic terranes can be roughly summarized into ten types:channel flow,diapiric exhumation,a coexistence mechanism of channel flow and diapiric exhumation,slab breakoff,multi-stage exhumation,divergent plate motion(including slab rollback and the upper-plate divergent motion away from the subducted plate),overthrust exhumation,overpressure mechanism,wedge-like extrusion and microplate rotation.The exhumation of high-density UHP oceanic eclogites is a relative controversial issue.Some of our recent researches on quantitatively determining the exhumation mechanism of UHP oceanic eclogites using thermomechanical and phase equilibrium modelling was introduced in details in this paper.We obtained the 3-D density evolutions of three-type subducted oceanic materials(MORB,serpentine and oceanic sediments)in P-T space by the methods of phase equilibrium and density calculation.According to the density difference between the metabasic and their surrounding rocks,the exhumed eclogites could be divided into two types.The first category,the self-exhumation eclogites(ρ_(MORB)<ρmantle),which can exhume driven by their own buoyancy,an example is the coesite-bearing oceanic eclogites from Southwest Tianshan.Another is the carried-exhumation eclogites(ρ_(MORB)>ρmantle),which can only be carried back to the surface with the assistance of low-density metasediments and serpentinite due to their negative buoyancy;the coesite-bearing UHP eclogites of Zermatt-Saas in the Western Alps is a typical example.Besides,we further explored the ultimate self-exhumation depth,exhumation mechanisms,the effect of the transition from high pressure to ultra-high pressure on the exhumation process of oceanic eclogites and the spatial distribution of exhumed HP-UHP metamorphic terranes.展开更多
A novel inverted telephoto four mirror zoom system with large field of view (FOV) was designed over a wide specWal bandwidth. The initial configuration of the zoom system was obtained by applying the aberration equa...A novel inverted telephoto four mirror zoom system with large field of view (FOV) was designed over a wide specWal bandwidth. The initial configuration of the zoom system was obtained by applying the aberration equations under certain constraints. Then, a method was presented to correlate the aspheric coefficients with the aberrations of this system. By using this method, the required image quality could be achieved after optimiza- tion using the ZEMAX Optical Design Code. Besides good image quality, another benefits of using this system is the potential for using cheap optics.展开更多
Spirulina platensis is an excellent carrier of Se,and thus widely used in medical fields and as well as in the food industry.However,there is little information about the characteristics and bioactivity of selenium-co...Spirulina platensis is an excellent carrier of Se,and thus widely used in medical fields and as well as in the food industry.However,there is little information about the characteristics and bioactivity of selenium-containing S.platensis proteins(Se-SP).In this study,Se-SP with different molecular weights were isolated from selenium-enriched S.platensis,and the bioactivities(such as antioxidant and anti-inflammatory activities)of Se-SP were investigated.Se-SP3(with a molecular weight range of 20-48 kDa)showed better free radical scavenging ability(ABTS)than the other Se-SPs.In addition,Se-SP3 suppressed inflammatory cytokines,in which decreased by 74% interleukin 6(IL-6),42.28% tumor necrosis factor-α(TNF-α),69.07% content of malondialdehyde(MDA),40.45% interleukin-1β(IL-1β)relative to the LPS group.Moreover,Se-SP3 decreased the nitric oxide(NO)production by 64.84% compared with the LPS group and increased the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px),indicating that Se-SP3 has excellent antioxidant and anti-inflammatory activities,and could be used as a functional food ingredient or natural medicine.展开更多
Numerous eclogite_amphibolite blocks have been found along the Mayanling fault in the northern Dabie complex. Most of the eclogites are strongly retrograded and contain garnet, rutile and the amphibole_plagioclase sym...Numerous eclogite_amphibolite blocks have been found along the Mayanling fault in the northern Dabie complex. Most of the eclogites are strongly retrograded and contain garnet, rutile and the amphibole_plagioclase symplectite. The occurrence of these eclogites may have something to do with the inverted movement of the Mayanling thrust fault.展开更多
基金supported by the NSF of China(Grant No.41520104004)。
文摘Knowing the phase relations of carbon-bearing phases at high-pressure(HP) and high-temperature(HT) condition is essential for understanding the deep carbon cycle in the subduction zones.In particular,the phase relation of carbon-bearing phases is also strongly influenced by redox condition of subduction zones,which is poorly explored.Here we summarized the phase relations of carbon-bearing phases(calcite,aragonite,dolomite,magnesite,graphite,hydrocarbon) in HP metamorphic rocks(marble,metapelite,eclogite) from the Western Tianshan subduction zone and high-pressure experiments.During prograde progress of subduction,carbonates in altered oceanic crust change from Ca-carbonate(calcite) to Ca,Mg-carbonate(dolomite),then finally to Mgcarbonate(magnesite) via Mg-Ca cation exchange reaction between silicate and carbonate,while calcite in sedimentary calcareous ooze on oceanic crust directly transfers to high-pressure aragonite in marble or amorphous CaCO3 in subduction zones.Redox evolution also plays a significant effect on the carbon speciation in the Western Tianshan subduction zone.The prograde oxygen fugacity of the Western Tianshan subduction zone was constrained by mineral assemblage of garnet-omphacite from FMQ-1.9 to FMQ-2.5 at its metamorphic peak(maximum P-T) conditions.In comparison with redox conditions of other subduction zones,Western Tianshan has the lowest oxygen fugacity.Graphite and light hydrocarbon inclusions were ubiqutously identified in Western Tianshan HP metamorphic rocks and speculated to be formed from reduction of Fe-carbonate at low redox condition,which is also confirmed by high-pressure experimental simulation.Based on petrological observation and high-pressure simulation,a polarized redox model of reducing slab but oxidizing mantle wedge in subduction zone is proposed,and its effect on deep carbon cycle in subduction zones is further discussed.
基金financially supported by the DREAM project of MOST,China(Grant No.2016YFC0600408)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB18000000)the Program of the National Mineral Rock and Fossil Specimens Resource Center from MOST,China。
文摘A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprobe and LA-ICP-MS were employed to quantity some major and trace elements,and unpolarized FTIR spectroscopy was applied to probe the different types of hydrogen defects,explore water-incorporation mechanisms and quantify water contents.Trace amounts of A1 and B were detected in the coesite.Combining our results with the results in the literatures,we have found no positive correlation between the Al contents and the"Al"-based hydrogen concentrations,suggesting that previously proposed hydrogen-incorporation mechanism H^++Al^3+■Si^4+does not function in coesite.In contrast,we have confirmed the positive correlation between the B contents and the B-based hydrogen concentrations.The hydrogen-incorporation mechanism H^++B3^+■Si^4+readily takes place in coesite at different P-T conditions,and significantly increases the water content at both liquid-saturated and liquid-undersaturated conditions.For the SiO2-H2O system,we have found that type-Ⅰhydrogarnet substitution plays a dictating role in incorporating water into coesite at liquid-saturated condition,type-II hydrogarnet substitution contributes significantly at nearly dry condition,and both operate at conditions in between.The water solubility of coesite,as dictated by the type-Ⅰhydrogarnet substitution,positively correlates with both P and T,cH2O=-105(30)+5.2(32)×P+0.112(26)×T,with cH2O in wt ppm,P in GPa and T in℃.Due to its low water solubility and small fraction in subducted slabs,coesite may contribute insignificantly to the vertical water transport in subduction zones.Furthermore,the water solubility of any coesite in exhuming ultra-high pressure metamorphic rocks should be virtually zero as coesite becomes metastable.With an adequately fast waterdiffusion rate,this metastable coesite should be completely dry,which may have been the key factor to the partial preservation of most natural Coe.As a byproduct,a new IR experimental protocol for accurate water determination in optically anisotropic nominally anhydrous minerals has been found.Aided with the empirical method of Paterson(1982)it employs multiple unpolarized IR spectra,collected from randomly-orientated mineral grains,to approximate both total integrated absorbance and total integrated molar absorption coefficient.Its success relies on a high-level orientation randomness in the IR analyses.
基金supported by the Chinese Major State Basic Research Program (Grants Nos.2009CB825007,2007CB411307)National Natural Science Foundation of China(Grant Nos.40730314,40821002, 41230207,41390441,41190075)the Molengraaff Fund to MCS
文摘The Chinese Tianshan belt of the southern Altaids has undergone a complicated geological evolution. Different theories have been proposed to explain its evolution and these are still hotly debated. The major subduction polarity and the way of accretion are the main problems. Southward, northward subduction and multiple subduction models have been proposed. This study focuses on the structural geology of two of the main faults in the region, the South Tianshan Fault and the Nikolaev Line. The dip direction in the Muzhaerte valley is southward and lineations all point towards the NW. Two shear sense motions have been observed within both of these fault zones, a sinistral one, and a dextral one, the latter with an age of 236-251 Ma. Structural analyses on the fault zones show that subduction has been northward rather than southward. The two shear sense directions indicate that the Yili block was first dragged along towards the east due to the cloclkwise rotation of the Tarim block. After the Tarim block stopped rotating, the Yili block still kept going eastward, inducing the dextral shear senses within the fault zones.
基金financially supported by the China Geological Survey Program(Grant Nos.1212011121260,1212011220928)the National Natural Science Foundation of China(Project No.491755206)。
文摘The Gejiu-Bozushan-Laojunshan W-Sn polymetallic metallogenic belt(GBLB)in southeast Yunnan Province is an important part of the southwestern Yangtze Block in South China.Tin polymetallic mineralization in this belt includes the Niusipo,Malage,Songshujiao,Laochang and Kafang ore fields in the Gejiu area which are spatially and temporally associated with the Kafang-Laochang and Songshujiao granite plutons.These granites are characterized by variable A/CNK values(mostly>1.1,except for two samples with 1.09),high contents of SiO2(74.38-76.84 wt.%)and Al2 O3(12.46-14.05 wt.%)and variable CaO/Na2 O ratios(0.2-0.65)as well as high zirconδ18O values(7.74‰-9.86‰),indicative of S-type affinities.These rocks are depleted in Rb,Th,U,Ti,LREE[(La/Yb)N=1.4-20.51],Ba,Nb,Sr,and Ti and display strong negative Eu and Ba anomalies.The rocks possess high Rb/Sr and Rb/Ba ratios,relatively low initial 87Sr/86Sr ratios(0.6917-0.7101),and less radiogenicεNd(t)values(-8.0 to-9.1).The zircon grains from these rocks show negativeεHf(t)values in the range of-3.7 to-9.9 with mean TDM2(Nd)and TDM2(Hf)values of 1.57 Ga and 1.55 Ga.They show initial 207Pb/204Pb ranging from15.69 to 15.71 and 206Pb/204Pb from 18.36 to 18.70.Monazite from Songshujiao granites exhibits higher U and lower Th/U ratios,lowerδ18O values and higherεHf(t)values than those of the zircon grains in the KafangLaochang granites.The geochemical and isotopic features indicate that the Laochang-Kafang granites originated by partial melting of Mesoproterozoic crustal components including biotite-rich metapelite and metagraywacke,whereas the Songshujiao granites were derived from Mesoproterozoic muscovite-rich metapelite crustal source.Most zircon grains from the Songshujiao,Laochang and Kafang granites have high-U concentrations and their SIMS U-Pb ages show age scatter from 81.6 Ma to 88.6 Ma,80.7 Ma to 86.1 Ma and 82.3 Ma to 87.0 Ma,suggesting formation earlier than the monazite and cassiterite.Monazite SIMS U-Pb ages and Th-Pb ages of three same granite samples are consistent and show yielded 206 Pb/238U ages of 83.7±0.6 Ma,83.7±0.6 Ma,and 83.4±0.6 Ma,and 208Pb/232Th ages of 83.2±0.5 Ma,83.8±0.4 Ma,and 83.5±0.9 Ma,which are within the range of the SIMS zircon U-Pb ages from these rocks.The data constrain the crystallization of the granites at ca.83 Ma.In situ U-Pb dating of two cassiterite samples from the cassiterite-sulfide ore in the Songshujiao ore field and Kafang ore field,and two from the cassiterite-oxide+cassiterite bearing dolomite in the Laochang ore field yielded weighted mean 206 Pb/238U ages of 83.5±0.4 Ma(MSWD=0.6),83.5±0.4 Ma(MSWD=0.5),83.6±0.4 Ma(MSWD=0.6)and 83.2±0.7 Ma(MSWD=0.6),respectively.Combined with geological characteristics,the new geochronological data indicate that the formation of the granites and Sn polymetallic deposits are coeval.We correlate the magmatic and metallogenic event with lithospheric thinning and asthenosphere upwelling in continental extension setting in relation to the eastward subduction of the Neo-Tethys beneath the Sanjiang tectonic domain during Late Cretaceous.
文摘The purpose of our study was to compare interfractional bony setup variations in pelvic anatomy with two immobilization devices, the patient-specific Vac-Lok and the generic Dual Leg Positioner system (both Civco Medical Solutions, Kalona, IA), for bilateral proton radiotherapy of the prostate. Two groups of 10 patients were studied. Computed tomography (CT) was performed three times a week, yielding 233 CT image sets for the vacuum system group and 252 for the other group. The translational shifts of the pelvic bone and prostate and rotation of the upper femurs of the femoral heads with respect to the simulation CT images were analyzed. Along the anterior-posterior and lateral axes, mean and systematic translational variations of the pelvic bone and prostate, relative to skin fiducials, were significantly lower in the Vac-Lok group (all p 0.01) than in the Dual Leg Positioner group. Abduction of the upper femur, the dominant rotation, had random rotational variations of 1.9° and 2.0° and systematic rotations of 3.1° and 2.9° for the vacuum and generic system groups, respectively. Femoral abduction was highly correlated with anterior prostate displacement for both femurs in both groups (p tion introduced during simulation CT, particularly with the generic immobilization system. High degrees of femoral rotation may introduce prostate translation and distal misalignment of lateral proton beams with the prostate.
文摘We proposed the use of a hybrid deformable image registration approach that combines compact-support radial basis functions (CSRBF) spline registration with intensity-based image registration. The proposed method first uses the pre-viously developed image intensity-based method to achieve voxel-by-voxel correspondences over the entire image re-gion. Next, for those areas of inaccurate registration, a sparse set of landmark correspondences was defined for local deformable image registration using a multi-step CSRBF approach. This hybrid registration takes advantage of both intensity-based method for automatic processing of entire images and the CSRBF spline method for fine adjustment over specific regions. The goal of using this hybrid registration is to locally control the quality of registration results in specific regions of interest with minimal human intervention. The major applications of this approach in radiation ther-apy are for the corrections of registration failures caused by various imaging artifacts resulting in, low image contrast, and non-correspondence situations where an object may not be imaged in both target and source images. Both synthetic and real patient data have been used to evaluate this hybrid method. We used contours mapping to validate the accuracy of this method on real patient image. Our studies demonstrated that this hybrid method could improve overall registra-tion accuracy with moderate overhead. In addition, we have also shown that the multi-step CSRBF registration proved to be more effective in handling large deformations while maintaining the smoothness of the transformation than origi-nal CSRBF.
基金supported by the China Geological Survey Program(Grant Nos.1212011121260,1212011220928)the National Natural Science Foundation of China(Gant No.91755206)。
文摘The South China Block(SCB)is among the large-scale W-Sn mineralized regions of the globe.The Laojunshan W-Sn-dominant ore area(LOA)in the western part of the SCB preserves the records of the tectonic history of the Tethys realm extending through North Vietnam,and Yangtze to Cathaysia blocks,with coeval formation of giant metallic deposits.The prolonged tectonic activities and their control on the genesis and spatio-temporal distribution of giant metallic deposits in the LOA provide a window for a holistic understanding of the tectono-metallogenesis of the SCB.In this study,we present results from a multi-chronologic study to determine the timing of formation of the cassiterite-wolframite-schee lite mineralization.The results suggest three distinct tectono-metallogenic periods in the LOA during the geodynamic evolution of the surrounding tectonic units.The opening of the Proto-Tethys Ocean between the Yangtze-Indochina blocks and the westward Paleo-Pacific subduction beneath the Cathaysia block(420–380 Ma)jointly contributed to the Silurian to early Devonian intracontinental orogeny in the middle of the SCB that involved top-to-the-north thrusting along NE-striking shear zones.This event generated the Dulong-Song Chay granitoids,together with the formation of Xinzhai Sn deposit related to sheared mylonitic granites(ca.419 Ma)and pegmatites(ca.389 Ma),which include the early-stage Sn-sulfide skarn(ca.418 Ma)and the late-stage Sn-bearing schist(ca.389 Ma).During the Late Permian to Late Triassic(260–220 Ma),with the closure of the Proto-Tethys oceans in the west and ongoing Paleo-Pacific westward subduction in the east,the SCB and Indochina Block(IB)were amalgamated which also marks the time of formation of the Nanwenhe scheelite skarn deposit.The subducted PaleoTethys oceanic crust was likely entrained by the nearby rising Emeishan mantle plume(270–259 Ma),which formed the Maguan diabase(ca.260 Ma)that shows significantly older Re-Os model age of ca.268 Ma,suggesting that the Nanwenhe mineralization is potentially derived from ca.260 Ma source.Furthermore,the intraplate shortening induced thin skinned crustal deformation and low grade metamorphism(ca.230 Ma),with the main stage of scheelite-Sn-Mo mineralization(229.9,229.8 and 219 Ma)and contemporary formation of the pegmatite(230.7 Ma).The Late Cretaceous involved two episodes of alternate extension and shortening,driven by the subduction polarity change from northwestward subduction of the Okhotomorsk block to northward subduction of the NeoTethys seafloor.The evolution of the LOA consists of the NW–SE transpression ending ca.100 Ma,the WNW–ESE extension in the earlier episode lasting from 100 Ma to 86 Ma,the WNW–ESE transpression beginning at ca.85 Ma and the NAS extension in the later episode during the latest Cretaceous,which produced the extension-related three periods of Laojunshan granitic magmatism and coeval Sn-W mineralization,with ages in the range of 90–89 Ma,87–85 Ma and 83–79 Ma.We also evaluate the implications of magmaticmetamorphic-metallogenic degassing on the regional paleoclimatic history.
基金financially supported by the National Natural Science Foundation of China (Nos. 41802070,41572051)the China Postdoctoral Science Foundation (No. 2018M631319)the Fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources
文摘Yushugou granulite-peridotite complex,located at the east part of the northern margin of South Tianshan,may represent an ophiolitic slice subducted to 40–50 km depth with high-pressure granulite facies metamorphism.Although a lot of studies have been conducted on rocks in this belt,the rock association and tectonic background of the ophiolitic slice are still in dispute.A detailed study on petrology,phase equilibrium modeling and U-Pb zircon ages have been performed on the metagabbro vein in peridotite unit to constrain the tectonic evolution of the Yushugou granulite-peridotite complex.Three stages of mineral assemblage in the metagabbro were defined as stage I:Cpx^A+Opx^A+Pl^A,which represents the original minerals of the metagabbro vein;stage II:Cpx^B+Opx^B+Pl^B+Spl,which represents the mineral assemblage of granulite facies metamorphism with peak P-T conditions of 4.2–6.9 kbar and 940–1070℃;stage III is characterized by the existence of prehnite,thomsonite and amphibole in the matrix,indicating that the metagabbro vein may be influenced by fluids during retrograde metamorphism.Combined with the crosscut relationship,it can be deduced that the metagabbro vein,together with the peridotite in Yushugou granulite-peridotite complex has experienced similar high-temperature granulite facies metamorphism.The zircon chronological data shows that the protolith age of the metagabbro vein is 400.5±6.2 Ma,reflecting Devonian magmatism event and the granulite facies metamorphism occurred at^270 Ma which may be related to the post-collisional magmatism.
基金supported by the National Basic Research Program of China(2012CB416606)MOST Special Fund from the State Key Laboratory of Continental Dynamics+2 种基金the Natural Science(NJ13032)Start-up Research(PR12104)Foundations of Northwest UniversityNatural Science Foundation of Education Department of Shaanxi Provincial Government(14JK1733)
文摘Pelitic granulite from the Khondalite Belt,North China Craton,is composed of garnet,sillimanite,perthite,biotite and quartz.Oriented rutile needles in garnet are reported for the first time from the granulite.The rutile needles have been identified by optical microscopy and confirmed by in situ Raman spectroscopy,where they show the characteristic bands at 446–448 and 610 cm-1.Because of their very strong shape preferred orientation in3–4 easily observable directions,these rutile needles are interpreted to have formed by precipitation during exhumation and cooling following peak metamorphism.The ternary feldspar geothermometer gives a peak metamorphic temperature of*980°C at 10 kbar.The presence of oriented rutile needles in garnet is suggested to be a valuable indicator of ultrahigh-temperature(UHT)metamorphism in the Khondalite Belt and therefore likely in other UHT terrains.
基金supported by the National Natural Science Foundation of China (41425010,41273034)the Public Welfare Industry Scientific Special Expenditure (201511022)the China Geological Survey Project (12120115027101,12120114022701)
文摘Geochronological investigation on gneisses of granitic to leucogranitic compositions in Cuona,south Tibet,reveal that their protoliths formed at 808.8 ± 7.9-816.4 ± 3.4 Ma and 855.8 ± 7.0 Ma,respectively.Zircon rims from the granitic gneiss record a metamorphic age of 739.4 ± 4.3 Ma.Lu-Hf isotopic analyses on zircon grains with Neoproterozoic ages yield negative ε_(Hf)(t) values from-9.0 to-4.2,and the corresponding two-stage Hf model ages are 1965-2228 Ma.Whole-rock geochemical data indicate that all granitic gneisses are K-riched calc-alkali series.These new data together with literature data show that(1) the Himalayan terrane experienced an episode of Neoproterozoic magmatism at 850-800 Ma;(2) the Neoproterozoic magma of granitic compositions were derived from partial melting of ancient crusts,possibly due to the thermal perturbation related with the breakup of the Rodinia supercontinent.
基金supported by the Chinese Major State Basic Research Program(2015CB856105)the National Natural Science Foundation of China(41520104004,41372004,and41330210)
文摘The sediments,including calcareous,siliciclastic and volcanoclastic,usually occupy>90%in volume of an accretionary complex and thus,if involved in subduction zones,their maximum return depths(i.e.,peak pressures)are fundamental to unravel the geodynamic processes during the convergence of plates[1].As a unique example of accreted complex returned from sub-arc depths(>90 km)worldwide.
基金financially supported by the National Natural Science Foundation of China(41372060,41330210 and 41202032)
文摘A newly developed microprobe-based methodology(the Flank Method)for Fe^(3+)/RFe quantification has been successfully applied to some natural garnets from the North Qilian eclogites by JEOL JXA-8100microprobe at Peking University.The results demonstrated an obvious discrepancy in comparison with the outcomes by conventional stoichiometric calculations.This methodology allows to measure theFe^(3+)/Rmeasurement of Fe^(3+)According to the compositional zonation displayed in the studied eclogitic garnets from North Qilian,a prograde metamorphic°C to 22 kbar,600°C was reconstructed.More interestingly,the measured Fe^(3+)/RFe ratios in garnets decreasing from core to rim may probably imply that the oxygen fugacity(f O_2)declines with the depth of the subduction zone.
基金supported by the project“Component’s digital transformation methods'fundamental research for micro-and nanosystems”(No.#0705-2020-0041).
文摘The features of carrier-based aircraft’s navigation systems during the approach and landing phases are investigated.A new adaptive Kalman filter with unknown state noise statistics is proposed to improve the accuracy of the INS/GNSS integrated navigation system.The adaptive filtering algorithm aims to estimate and adapt the unknown state noise covariance Q in high dynamic conditions,when the measurement noise covariance R is assumed to be known empirically in advance.The new adaptive Kalman filter based on the innovation sequence and pseudo-measurement vector approach makes it more effective to estimate and adapt Q.The simulation results and semi-physical experiments show that the application of the proposed adaptive Kalman filter can guarantee a higher estimation accuracy of the state variables.
基金supported by the National Natural Science Foundation of China (Nos. 41350110224, 41750110483, 41730426, 41872066)the Open Research Project of the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (No. GPMR201820)
文摘Ophiolites play a key role in understanding subduction-accretion-collision processes. Herein, we discuss origin and metamorphic evolution of an enigmatic, Neoproterozoic ophiolite candidate—the mafic-ultramafic Songshugou Complex, Qinling belt, China—summarizing published thermobarometr);U/Pb geochronology, and geochemistry and presenting new phase equilibrium modeling. Garnet, rarely preserved in amphibolites of the Songshugou Complex, has prograde zoning and low-pvrope cores |Alm54-71(Grs+And)25-30PrP1-6Sps5-12. It formed at quartz eclogite facies conditions of 1.93-2.54 GPa, 462-542℃. During exhumation, garnet first was mantled by plagioclase-rich coronas at about 0.7-1.2 GPa, 660-710℃. During an isothermal uplift to 0.5-0.8 GPa, these coronas evolved widely into n-shaped aggregates and eventually into whitish ribbons oriented with a steeply southwest dipping mineral stretching lineation. The exhumation into middle-upper crustal levels proceeded till the Late Devonian. The oceanic protoliths of the eclogites were emplaced into continental crust in the Neoproterozoic and dragged into a subduction zone in North Qinling in the Cambrian. The ultramafic rocks of the Songshugou Complex were not subducted with the mafic rocks in a coherent block given the absence of garnet but ubiquitous occurrence of spinel implies a P maximum of ?1.7 GPa. Rather, mafic and ultramafic rocks belonged to downgoing and overriding plate, respectively. They were juxtaposed at 0.8-1.7 GPa at Early Ordovician time.
基金financially supported by the National Nature Science Foundation of China (41202032, 412111062 and 41311120071)
文摘The first Archean eclogite was announced from the Salma and Gridino complexes of Belomorian Province(Russia)in Fennoscandian Shield(Fig.1a)[1]that has aroused quite a resonance worldwide from all aspects;the debates on the actual age of the Belomorian eclogites have never stopped ever since and in all there are three scenarios are suggested(1)one time in Mesoarchean,(2)two times in Neoarchean and Paleoproterozoic and(3)one time
基金the National Basic Research Program of China(Grant No.2015CB856105)the National Natural Science Foundation of China(Grant Nos.91755206,41520104004).
文摘In terms of petrology,thermomechanical simulation is an important frontier to study the geodynamic process of the exhumation and uplift of high pressure(HP)to ultrahigh pressure(UHP)metamorphic rocks in subduction zones and collision orogenic belts.Based on the recent petrological studies and numerical modellings for the exhumation of HP to UHP metamorphic terranes,the exhumation mechanisms of HP to UHP metamorphic terranes can be roughly summarized into ten types:channel flow,diapiric exhumation,a coexistence mechanism of channel flow and diapiric exhumation,slab breakoff,multi-stage exhumation,divergent plate motion(including slab rollback and the upper-plate divergent motion away from the subducted plate),overthrust exhumation,overpressure mechanism,wedge-like extrusion and microplate rotation.The exhumation of high-density UHP oceanic eclogites is a relative controversial issue.Some of our recent researches on quantitatively determining the exhumation mechanism of UHP oceanic eclogites using thermomechanical and phase equilibrium modelling was introduced in details in this paper.We obtained the 3-D density evolutions of three-type subducted oceanic materials(MORB,serpentine and oceanic sediments)in P-T space by the methods of phase equilibrium and density calculation.According to the density difference between the metabasic and their surrounding rocks,the exhumed eclogites could be divided into two types.The first category,the self-exhumation eclogites(ρ_(MORB)<ρmantle),which can exhume driven by their own buoyancy,an example is the coesite-bearing oceanic eclogites from Southwest Tianshan.Another is the carried-exhumation eclogites(ρ_(MORB)>ρmantle),which can only be carried back to the surface with the assistance of low-density metasediments and serpentinite due to their negative buoyancy;the coesite-bearing UHP eclogites of Zermatt-Saas in the Western Alps is a typical example.Besides,we further explored the ultimate self-exhumation depth,exhumation mechanisms,the effect of the transition from high pressure to ultra-high pressure on the exhumation process of oceanic eclogites and the spatial distribution of exhumed HP-UHP metamorphic terranes.
文摘A novel inverted telephoto four mirror zoom system with large field of view (FOV) was designed over a wide specWal bandwidth. The initial configuration of the zoom system was obtained by applying the aberration equations under certain constraints. Then, a method was presented to correlate the aspheric coefficients with the aberrations of this system. By using this method, the required image quality could be achieved after optimiza- tion using the ZEMAX Optical Design Code. Besides good image quality, another benefits of using this system is the potential for using cheap optics.
基金financially supported by the Key Projects in Guangxi(2019GXNSFDA245008)Guangxi Natural Science Foundation(2017GXNSFAA198297)+1 种基金Guangxi Science and Technology Major Special Project(AA17204075,AA17202010-3)Guangxi Natural Science Foundation(2020GXNSFAA297038).
文摘Spirulina platensis is an excellent carrier of Se,and thus widely used in medical fields and as well as in the food industry.However,there is little information about the characteristics and bioactivity of selenium-containing S.platensis proteins(Se-SP).In this study,Se-SP with different molecular weights were isolated from selenium-enriched S.platensis,and the bioactivities(such as antioxidant and anti-inflammatory activities)of Se-SP were investigated.Se-SP3(with a molecular weight range of 20-48 kDa)showed better free radical scavenging ability(ABTS)than the other Se-SPs.In addition,Se-SP3 suppressed inflammatory cytokines,in which decreased by 74% interleukin 6(IL-6),42.28% tumor necrosis factor-α(TNF-α),69.07% content of malondialdehyde(MDA),40.45% interleukin-1β(IL-1β)relative to the LPS group.Moreover,Se-SP3 decreased the nitric oxide(NO)production by 64.84% compared with the LPS group and increased the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px),indicating that Se-SP3 has excellent antioxidant and anti-inflammatory activities,and could be used as a functional food ingredient or natural medicine.
文摘Numerous eclogite_amphibolite blocks have been found along the Mayanling fault in the northern Dabie complex. Most of the eclogites are strongly retrograded and contain garnet, rutile and the amphibole_plagioclase symplectite. The occurrence of these eclogites may have something to do with the inverted movement of the Mayanling thrust fault.