Using seismic waveform data recorded at station YK (Yingkou) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) eart...Using seismic waveform data recorded at station YK (Yingkou) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) earthquake in November 29, 1999 with SAM method. The results show that the predominant polarizations of fast shear-waves at YK is in direction of ENE-WSW, consistent with the direction of regional principal compressive stress and also consistent with the direction of the regional tectonic stress field in North China; time-delays increasing before Xiuyan earthquake may shows accumulation of stress before earthquake. The predominant polarizations of fast shear-waves at YK are also related to the spatial distribution of small earthquakes and correlate with the fault strike. The histogram of monthly average polarizations of fast shear-waves shows that polarizations of fast shear-waves also seems to change from two months before the earthquake, but it still needs more data for verification.展开更多
Having beautiful colours and fine features, Xiuyan jade is famous in the world. Mineralogically, Xiuyan jade is serpentine jade. XRD, IR and TEM studies indicate that the jade consists mainly of antigorite (m{Mg3(1-1/...Having beautiful colours and fine features, Xiuyan jade is famous in the world. Mineralogically, Xiuyan jade is serpentine jade. XRD, IR and TEM studies indicate that the jade consists mainly of antigorite (m{Mg3(1-1/m)[Si2O5](OH)1+3(1-2/m}) with a minor amount of chrysotile. Two favourite samples (PxA, Px1-1), chosen for research on Fe Mossbauer spectra, are only antigorite. Studies indicate that: a. iron ion in antigorite enters the lattice as impurity; b. Fe2+ and Fe3+ substitute for Mg in the coordination octahedron; and c. the colour of jade is related to content of Fe, and Fe2+/Fe3+≤1 is favourite for colour-forming.展开更多
By using crater impact morphological theory and mathematics modeling,the paper studies the cratering process and morphological features of the Xiuyan Crater in Northeast China based on remote sensing imagery,digital e...By using crater impact morphological theory and mathematics modeling,the paper studies the cratering process and morphological features of the Xiuyan Crater in Northeast China based on remote sensing imagery,digital elevation model(DEM)and drilling and measuring data.The results show that:1)Simulated calculation indicates the diameter of the transient crater was1406±12 m and the depth was 497±4 m.The diameter of the final crater was 1758±15 m and the depth was 374.5±3.5 m;the thickness of the breccia lens was 188.5±0.5 m.The data is basically the same as previous drilling data.2)Preliminary determination of the size of Xiuyan impactor:The diameter at about 55 m for an iron meteorite,and about 115 m for a stony meteorite.3)The depth-to-diameter ratio is 0.143,similar to the typical simple crater.The circularity index of the Xiuyan Crater is0.884,indicating erosion and degradation.4)The distribution pattern of radial fractures has priority in NW-SE and WNW-ESE and these fractures control the development and evolution of drainage inside the crater.展开更多
In this research, we studied the distribution of impact melt layers underneath Xiuyan crater using hydrocode simulation. The target was modeled by granite based on the rock type distribution around the crater and proj...In this research, we studied the distribution of impact melt layers underneath Xiuyan crater using hydrocode simulation. The target was modeled by granite based on the rock type distribution around the crater and projector by iron, because most small and isolated terrestrial craters are formed by iron projectile. The simulated crater diameter and depth are 1 710 and 320 m, respectively, which are in good agreement with observations of 1 800 and 307 m（except for the postimpact lacustrine sedimentation）. The validated model shows that impact melt materials were first formed along the transient crater floor and wall by highshock pressure, and then refilled inward the crater along with collapse of the crater wall. The final style of impact melt materials is interbedded with shock breccia underneath the crater center, which is verified through two layers in the borehole located in the crater center.展开更多
The well-preserved 1.8-km-diameter Xiuyan crater is located in the low mountain-hill region of the northern part of Liaodong Peninsula of northern China. Recently, a 307-m-deep borehole at the centre of crater became ...The well-preserved 1.8-km-diameter Xiuyan crater is located in the low mountain-hill region of the northern part of Liaodong Peninsula of northern China. Recently, a 307-m-deep borehole at the centre of crater became available. After penetrating 107 m lacustrine sediments, a breccia lens about 188 m in thickness was encountered. The crater-fill breccia is deposits of rock clasts and fragments more or less shock-metamorphosed. The features of geological structure and stratigraphic configuration within the crater, shock-melted rocks, and PDFs in quartz found in the basement rocks close to the crater rim and in the crater-fill breccia provide clear evidence for an impact origin of the Xiuyan crater.展开更多
Abundant TiO2-Ⅱ,a high-pressure polymorph of titanium dioxide,was found in the gneiss fragments of impact-produced breccias from the Xiuyan crater.Rutile in the gneiss was severely fragmented and fine-grained clasts ...Abundant TiO2-Ⅱ,a high-pressure polymorph of titanium dioxide,was found in the gneiss fragments of impact-produced breccias from the Xiuyan crater.Rutile in the gneiss was severely fragmented and fine-grained clasts less than 2 m in size had been transformed to TiO2-II.Irregular thin layered TiO2-Ⅱ is also observed in coarse-grained rutile fragments,where the TiO2-Ⅱ layers distributes along fractures and cracks in rutile.About 30 percent of rutile in the gneiss had been transformed to TiO2-Ⅱ.Fine grains of TiO2-Ⅱ display light bluish grey to light yellow brown in plane-polarized reflected light.Crystallographic investigation shows that TiO2-Ⅱ has an orthorhombic structure with space group Pbcn.The cell parameters are a=4.543(1),b=5.491(9)and c=4.895(2).Its empirical formula calculated on the basis of two oxygen atoms can be written as(Ti0.985Fe0.008Nb0.006-Si0.003Zr0.001)1.003O2,or simply formula TiO2.According to the shock effects of quartz and feldspars,the peak shock pressure and post-shock temperature in the TiO2-Ⅱ-bearing gneiss are estimated to be between 35 and 43 GPa and 300–900°C,respectively.The finding of TiO2-Ⅱ in the shock-metamorphosed gneiss provides another mineral physics evidence for shock origin of the Xiuyan crater.展开更多
Up to now,176 meteorite impact craters have been found on the Earth.Among these craters,none of them lies in China.The Xiuyan crater is located in the Liaodong Peninsula of China.This bowl-shaped crater has a diameter...Up to now,176 meteorite impact craters have been found on the Earth.Among these craters,none of them lies in China.The Xiuyan crater is located in the Liaodong Peninsula of China.This bowl-shaped crater has a diameter of 1.8 km and depth of about 150 m.The impact-derived features include planar deformation features(PDFs)in quartz,shatter cones,impact breccia,and radial valleys on the wall of rim.It is the first confirmed meteorite impact crater in China.展开更多
基金Basis and Special Research Foundation, Institute of Earthquake Science, China Earthquake Administration (2007-24)
文摘Using seismic waveform data recorded at station YK (Yingkou) of Liaoning Telemetry Digital Seismic Network, this paper studied the characteristics of shear-wave splitting before and after the Xiuyan MS5.9 (ML5.3) earthquake in November 29, 1999 with SAM method. The results show that the predominant polarizations of fast shear-waves at YK is in direction of ENE-WSW, consistent with the direction of regional principal compressive stress and also consistent with the direction of the regional tectonic stress field in North China; time-delays increasing before Xiuyan earthquake may shows accumulation of stress before earthquake. The predominant polarizations of fast shear-waves at YK are also related to the spatial distribution of small earthquakes and correlate with the fault strike. The histogram of monthly average polarizations of fast shear-waves shows that polarizations of fast shear-waves also seems to change from two months before the earthquake, but it still needs more data for verification.
文摘Having beautiful colours and fine features, Xiuyan jade is famous in the world. Mineralogically, Xiuyan jade is serpentine jade. XRD, IR and TEM studies indicate that the jade consists mainly of antigorite (m{Mg3(1-1/m)[Si2O5](OH)1+3(1-2/m}) with a minor amount of chrysotile. Two favourite samples (PxA, Px1-1), chosen for research on Fe Mossbauer spectra, are only antigorite. Studies indicate that: a. iron ion in antigorite enters the lattice as impurity; b. Fe2+ and Fe3+ substitute for Mg in the coordination octahedron; and c. the colour of jade is related to content of Fe, and Fe2+/Fe3+≤1 is favourite for colour-forming.
基金supported by National Natural Science Foundation of China(Grant No.60972141)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA04077200)National High-Tech Research and Development Program of China(Grant No.2010AA122202)
文摘By using crater impact morphological theory and mathematics modeling,the paper studies the cratering process and morphological features of the Xiuyan Crater in Northeast China based on remote sensing imagery,digital elevation model(DEM)and drilling and measuring data.The results show that:1)Simulated calculation indicates the diameter of the transient crater was1406±12 m and the depth was 497±4 m.The diameter of the final crater was 1758±15 m and the depth was 374.5±3.5 m;the thickness of the breccia lens was 188.5±0.5 m.The data is basically the same as previous drilling data.2)Preliminary determination of the size of Xiuyan impactor:The diameter at about 55 m for an iron meteorite,and about 115 m for a stony meteorite.3)The depth-to-diameter ratio is 0.143,similar to the typical simple crater.The circularity index of the Xiuyan Crater is0.884,indicating erosion and degradation.4)The distribution pattern of radial fractures has priority in NW-SE and WNW-ESE and these fractures control the development and evolution of drainage inside the crater.
基金supported by the National Natural Science Foundation of China (Nos.41472303,41490635)
文摘In this research, we studied the distribution of impact melt layers underneath Xiuyan crater using hydrocode simulation. The target was modeled by granite based on the rock type distribution around the crater and projector by iron, because most small and isolated terrestrial craters are formed by iron projectile. The simulated crater diameter and depth are 1 710 and 320 m, respectively, which are in good agreement with observations of 1 800 and 307 m（except for the postimpact lacustrine sedimentation）. The validated model shows that impact melt materials were first formed along the transient crater floor and wall by highshock pressure, and then refilled inward the crater along with collapse of the crater wall. The final style of impact melt materials is interbedded with shock breccia underneath the crater center, which is verified through two layers in the borehole located in the crater center.
基金supported by the Knowedge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-140)The National Natural Science Foundation of China (40872041)the President Foundation of Chinese Academy of Sciences (2007)
文摘The well-preserved 1.8-km-diameter Xiuyan crater is located in the low mountain-hill region of the northern part of Liaodong Peninsula of northern China. Recently, a 307-m-deep borehole at the centre of crater became available. After penetrating 107 m lacustrine sediments, a breccia lens about 188 m in thickness was encountered. The crater-fill breccia is deposits of rock clasts and fragments more or less shock-metamorphosed. The features of geological structure and stratigraphic configuration within the crater, shock-melted rocks, and PDFs in quartz found in the basement rocks close to the crater rim and in the crater-fill breccia provide clear evidence for an impact origin of the Xiuyan crater.
基金supported by the National Natural Science Foundation of China(41172044)GIG CAS 135 Project(Y234071001)contribution No.IS-1595 from GIGCAS
文摘Abundant TiO2-Ⅱ,a high-pressure polymorph of titanium dioxide,was found in the gneiss fragments of impact-produced breccias from the Xiuyan crater.Rutile in the gneiss was severely fragmented and fine-grained clasts less than 2 m in size had been transformed to TiO2-II.Irregular thin layered TiO2-Ⅱ is also observed in coarse-grained rutile fragments,where the TiO2-Ⅱ layers distributes along fractures and cracks in rutile.About 30 percent of rutile in the gneiss had been transformed to TiO2-Ⅱ.Fine grains of TiO2-Ⅱ display light bluish grey to light yellow brown in plane-polarized reflected light.Crystallographic investigation shows that TiO2-Ⅱ has an orthorhombic structure with space group Pbcn.The cell parameters are a=4.543(1),b=5.491(9)and c=4.895(2).Its empirical formula calculated on the basis of two oxygen atoms can be written as(Ti0.985Fe0.008Nb0.006-Si0.003Zr0.001)1.003O2,or simply formula TiO2.According to the shock effects of quartz and feldspars,the peak shock pressure and post-shock temperature in the TiO2-Ⅱ-bearing gneiss are estimated to be between 35 and 43 GPa and 300–900°C,respectively.The finding of TiO2-Ⅱ in the shock-metamorphosed gneiss provides another mineral physics evidence for shock origin of the Xiuyan crater.
基金President Foundation of Chinese Academy of Sciences(2007)the National Natural Science Foundation of China(Grant No.40672035)
文摘Up to now,176 meteorite impact craters have been found on the Earth.Among these craters,none of them lies in China.The Xiuyan crater is located in the Liaodong Peninsula of China.This bowl-shaped crater has a diameter of 1.8 km and depth of about 150 m.The impact-derived features include planar deformation features(PDFs)in quartz,shatter cones,impact breccia,and radial valleys on the wall of rim.It is the first confirmed meteorite impact crater in China.
