Based on the analysis of trace fossils collected from the typical outcrop of the Lower Cambrian Wusongger Formation in the Kalpin area, ten ichnospecies of six ichnogenus were identified in the upper member of the Wus...Based on the analysis of trace fossils collected from the typical outcrop of the Lower Cambrian Wusongger Formation in the Kalpin area, ten ichnospecies of six ichnogenus were identified in the upper member of the Wusongger Formation, with most of them being found for the first time. The trace fossils are described seriatim. The ichnospecies are mainly represented by such common trace fossils as Ophiomorpha nodosa, Helminthopsis hieroglyphica, Helminthopsis ichnosp., Planolites beverleyensis, Planolites vulgaris, Planolites montanus, Palaeophycus striatus, Palaeophycus curvatus, Cochlichnus anguineus and Rituichnus elongatum. The trace fossils are of high diversity and low abundance, and can be diagnosed as the Cruziana ichnofacies. They can be interpreted as having formed in a shallow water environment.展开更多
Due to the effect of the collision between the Indian plate and Eurasian plate, Pamirs is constantly moving to the north. Under the interaction among multiple tectonic blocks, strong earthquakes often occurred around ...Due to the effect of the collision between the Indian plate and Eurasian plate, Pamirs is constantly moving to the north. Under the interaction among multiple tectonic blocks, strong earthquakes often occurred around the Kalpin block which is located in western Tianshan of Chinese continent. In this paper, we used Intefferometric Synthetic Aperture Radar （InSAR） technique and adopted stacking algorithm to achieve the present-day crustal deformation field of the Kalpin block region based on 38 Envisat ASAR images. The results show that the deformation in radar line of sight around Kalpin block is mainly compressive between south and north with magnitude 1-1.5 mm/a. Displacement decreases gradually from northwest to southeast, which is consistent with the deformation characteristics shown in Tianshan, i.e. crust is gradually shortening from west to east detected by the GPS observations. Also, the Piqiang fault zone is uplifting. And there is an obvious displacement difference between the two sides of the Aozigeertawu fault.展开更多
This paper introduces the basic parameters,focal mechanism solutions and earthquake sequence characteristics of the Kalpin M_S5.3 earthquake sequence of December 1,2013,and analyzed seismic activity before the earthqu...This paper introduces the basic parameters,focal mechanism solutions and earthquake sequence characteristics of the Kalpin M_S5.3 earthquake sequence of December 1,2013,and analyzed seismic activity before the earthquake,the adjacent tectonic features and the precursory anomaly at fixed points within a range of 200 km. Research indicates:(1) The earthquake occurred on Kalpin fault,the source rupture type is thrust faulting with sinistral strike-slip component.( 2) The earthquake sequence is mainshock-aftershock type,with the aftershock distribution attenuating quickly and trending NE.(3) Abnormal seismic activity before the earthquake was characterized by seismically nesting quiescence of MS2. 0-4. 0 earthquakes,seismic quiescence of MS4. 0 earthquakes and seismic belts of MS3. 0 earthquakes in the Kalpin block, abnormal enhancement zone of moderate earthquakes on Puchang fault and seismological parameters.(4) Anomalies of precursory observation data at fixed stations are mainly characterized by mutation. Apart from the borehole tiltmeter in Halajun, the spatial distribution of other abnormal precursors showed a phenomenon of migration from the near field to far field and from the epicenter to the peripheries.展开更多
Deformation patterns, shortening amounts and rates in the late Quaternary across the Kalpin thrust system have received tittle attention in the past. This paper attempts to discuss them, mainly in the eastern part of ...Deformation patterns, shortening amounts and rates in the late Quaternary across the Kalpin thrust system have received tittle attention in the past. This paper attempts to discuss them, mainly in the eastern part of the thrust system by doing field investigation along the faults and folds, measuring geomorphic deformation, excavating trenches in several important sites where young alluvial fans were obviously displaced and dating young deposits of alluvial terraces. There are two types of deformation in the surface and near surface for the Kalpin thrust system in the late Quaternary. They are movement of thrust faults on lower angles and bending of young folds. Both kinds of deformation are shown by shortening and uplifting of young geomorphic surfaces. The surface ages of 3 stages are calculated by dating 20 examples using the TL method in the study area and comparing the results of our predecessors on the deposition and incision times of alluvial terraces in the Tianshan mountain which are 100ka B. P., 33 - 18ka B.P. and 6.6 - 8.2ka B.P. respectively for the large-scale deformed alluvial surfaces： T3, T2 and T1 in the Kalpin region. Then, 19 sets of shortening amounts and rates are obtained in 13 sites along 4 rows of anticlines in front of the Kalpin thrust system and Piqiang fold. The shortening amounts and rates show that there are two sections where deformation is stronger than others. The two sections consist of two arcs that are towards the south. The shortening rates near the top of arcs are 1.32mm/a in the west and 1.39mm/a in the east across the thrust system, respectively. In addition, deformation is stronger in the front rows than the rear ones for bifurcate folds.展开更多
The Kalpin nappe structure is a strongest thrust and fold deformation belt in front of the Tianshan Mountains since the Cenozoic time. The tectonic deformation occurred in 5―6 striking Meso-zoic-Cenozoic fold zones, ...The Kalpin nappe structure is a strongest thrust and fold deformation belt in front of the Tianshan Mountains since the Cenozoic time. The tectonic deformation occurred in 5―6 striking Meso-zoic-Cenozoic fold zones, and some renascent folds formed on the recent alluvial-proluvial fans in front of the folded mountains. We used the total station to measure gully terraces along the longitudinal to-pographic profile in the renascent fold zones and collected samples from terrace deposits for age de-termination. Using the obtained formation time and shortening amount of the deformed terraces, we calculated the shortening rate of 4 renascent folds to be 0.1±0.03 mm/a, 0.12±0.04 mm/a, 0.59±0.18 mm/a, and 0.26±0.08 mm/a, respectively. The formation time of the renascent folds is some later than the major tectonic uplift event of the Qinghai-Tibet Plateau 0.14 Ma ago. It may be the long-distance effect of this tectonic event on the Tianshan piedmont fold belt.展开更多
基金supported by National Natural Science Foundation of China (No. 41072102)the National Basic Research Program of China(No.2012CB214804)
文摘Based on the analysis of trace fossils collected from the typical outcrop of the Lower Cambrian Wusongger Formation in the Kalpin area, ten ichnospecies of six ichnogenus were identified in the upper member of the Wusongger Formation, with most of them being found for the first time. The trace fossils are described seriatim. The ichnospecies are mainly represented by such common trace fossils as Ophiomorpha nodosa, Helminthopsis hieroglyphica, Helminthopsis ichnosp., Planolites beverleyensis, Planolites vulgaris, Planolites montanus, Palaeophycus striatus, Palaeophycus curvatus, Cochlichnus anguineus and Rituichnus elongatum. The trace fossils are of high diversity and low abundance, and can be diagnosed as the Cruziana ichnofacies. They can be interpreted as having formed in a shallow water environment.
基金supported by the National Natural Science Foundation of China(41174083)Special Project for Overseas Returnees(2013)the Special Research Project of China Earthquake Administration(201208009)
文摘Due to the effect of the collision between the Indian plate and Eurasian plate, Pamirs is constantly moving to the north. Under the interaction among multiple tectonic blocks, strong earthquakes often occurred around the Kalpin block which is located in western Tianshan of Chinese continent. In this paper, we used Intefferometric Synthetic Aperture Radar （InSAR） technique and adopted stacking algorithm to achieve the present-day crustal deformation field of the Kalpin block region based on 38 Envisat ASAR images. The results show that the deformation in radar line of sight around Kalpin block is mainly compressive between south and north with magnitude 1-1.5 mm/a. Displacement decreases gradually from northwest to southeast, which is consistent with the deformation characteristics shown in Tianshan, i.e. crust is gradually shortening from west to east detected by the GPS observations. Also, the Piqiang fault zone is uplifting. And there is an obvious displacement difference between the two sides of the Aozigeertawu fault.
文摘This paper introduces the basic parameters,focal mechanism solutions and earthquake sequence characteristics of the Kalpin M_S5.3 earthquake sequence of December 1,2013,and analyzed seismic activity before the earthquake,the adjacent tectonic features and the precursory anomaly at fixed points within a range of 200 km. Research indicates:(1) The earthquake occurred on Kalpin fault,the source rupture type is thrust faulting with sinistral strike-slip component.( 2) The earthquake sequence is mainshock-aftershock type,with the aftershock distribution attenuating quickly and trending NE.(3) Abnormal seismic activity before the earthquake was characterized by seismically nesting quiescence of MS2. 0-4. 0 earthquakes,seismic quiescence of MS4. 0 earthquakes and seismic belts of MS3. 0 earthquakes in the Kalpin block, abnormal enhancement zone of moderate earthquakes on Puchang fault and seismological parameters.(4) Anomalies of precursory observation data at fixed stations are mainly characterized by mutation. Apart from the borehole tiltmeter in Halajun, the spatial distribution of other abnormal precursors showed a phenomenon of migration from the near field to far field and from the epicenter to the peripheries.
基金The research was sponsored by"Special Project of Emergency Response to the MS 6 .8 Bachu-Jiashi , Xinjiang Earthquake"of China Earthquake Administration
文摘Deformation patterns, shortening amounts and rates in the late Quaternary across the Kalpin thrust system have received tittle attention in the past. This paper attempts to discuss them, mainly in the eastern part of the thrust system by doing field investigation along the faults and folds, measuring geomorphic deformation, excavating trenches in several important sites where young alluvial fans were obviously displaced and dating young deposits of alluvial terraces. There are two types of deformation in the surface and near surface for the Kalpin thrust system in the late Quaternary. They are movement of thrust faults on lower angles and bending of young folds. Both kinds of deformation are shown by shortening and uplifting of young geomorphic surfaces. The surface ages of 3 stages are calculated by dating 20 examples using the TL method in the study area and comparing the results of our predecessors on the deposition and incision times of alluvial terraces in the Tianshan mountain which are 100ka B. P., 33 - 18ka B.P. and 6.6 - 8.2ka B.P. respectively for the large-scale deformed alluvial surfaces： T3, T2 and T1 in the Kalpin region. Then, 19 sets of shortening amounts and rates are obtained in 13 sites along 4 rows of anticlines in front of the Kalpin thrust system and Piqiang fold. The shortening amounts and rates show that there are two sections where deformation is stronger than others. The two sections consist of two arcs that are towards the south. The shortening rates near the top of arcs are 1.32mm/a in the west and 1.39mm/a in the east across the thrust system, respectively. In addition, deformation is stronger in the front rows than the rear ones for bifurcate folds.
基金Supported by the National Natural Science Foundation of China (Grant No. 40572126)China Earthquake Administration under project Integrated Investiga-tion of Seismogenic Structures for Intermediate-Strong Earthquakes in Jiashi-Bachu of Xinjiang Uygur Autonomous Region.
文摘The Kalpin nappe structure is a strongest thrust and fold deformation belt in front of the Tianshan Mountains since the Cenozoic time. The tectonic deformation occurred in 5―6 striking Meso-zoic-Cenozoic fold zones, and some renascent folds formed on the recent alluvial-proluvial fans in front of the folded mountains. We used the total station to measure gully terraces along the longitudinal to-pographic profile in the renascent fold zones and collected samples from terrace deposits for age de-termination. Using the obtained formation time and shortening amount of the deformed terraces, we calculated the shortening rate of 4 renascent folds to be 0.1±0.03 mm/a, 0.12±0.04 mm/a, 0.59±0.18 mm/a, and 0.26±0.08 mm/a, respectively. The formation time of the renascent folds is some later than the major tectonic uplift event of the Qinghai-Tibet Plateau 0.14 Ma ago. It may be the long-distance effect of this tectonic event on the Tianshan piedmont fold belt.
