Continent-continent collision is the most important driving mechanism for the occurrence of various geological processes in the continental lithosphere. How to recognize and determine continent-continent collision, es...Continent-continent collision is the most important driving mechanism for the occurrence of various geological processes in the continental lithosphere. How to recognize and determine continent-continent collision, especially its four-dimensional temporal-spatial evolution, is a subject that geological communities have long been concerned about and studied. Continent-continent collision is mainly manifested by strong underthrusting (subduction) of the underlying block along an intracontinental subduction zone and continuous obduction (thrusting propagation) of the overlying block along the intracontinental subduction zone, the occurrence of a basin-range tectonic framework in a direction perpendicular to the subduction zone and the flexure and disruption of the Moho. On the basis of numerical modeling, the authors discuss in detail the couplings between various amounts and rates of displacement caused by basin subsidence, mountain uplift and Moho updoming and downflexure during obduction (thrusting propagation) and subduction and the migration pattern of basin centers. They are probably indications or criteria for judgment or determination of continent-continent collision.展开更多
Along the western Kunlun-Tarim-Tianshan geoscience transect in the northwestern China, an integrated geophysical investigation was carried out. Owing to the abominable natural conditions there, the sounding profile co...Along the western Kunlun-Tarim-Tianshan geoscience transect in the northwestern China, an integrated geophysical investigation was carried out. Owing to the abominable natural conditions there, the sounding profile could not cross the whole transect, consequentially, a variety of velocity structures in the transverse and vertical orientations beneath the whole transect were not obtained, such as the case within the western Kunlun orogenic belt. To supply a gap of deep seismic soundings within the western Kunlun orogenic belt, we used the Bouguer gravity anomaly data and the relationship between the compressive wave and the density to obtain the density structure of the crust beneath the western Kunlun and the southern Tarim basin by a forward fitting of gravity anomalies within the two-dimensional polygonal model of uniform medium. The crust of the Tarim basin with a rigid basement was like an asymmetrical arc, whose surface feature was the Bachu uplift in the middle of the Tarim basin. Beneath the conjoint area between the Tarim basin and the western Kunlun belt, there was a V-shape structure located just up to the top of the uplifted Moho. The multi-seismological structures jointly revealed that the face-to-face continent-continent collision beneath the western Kunlun is a new structural style within the continent-continent collision zone, which is a real model proved by the numerical modeling.展开更多
SAR弧的磁层源区对应环电流与等离子体层顶重叠区域,而等离子体层顶常常观测到密度不规则结构.之前还没有暴时等离子体层顶密度不规则结构对SAR弧调制的观测报道.本文报道了地基成像和磁层、电离层卫星对2013年10月9日磁暴恢复相期间发...SAR弧的磁层源区对应环电流与等离子体层顶重叠区域,而等离子体层顶常常观测到密度不规则结构.之前还没有暴时等离子体层顶密度不规则结构对SAR弧调制的观测报道.本文报道了地基成像和磁层、电离层卫星对2013年10月9日磁暴恢复相期间发生的SAR弧的联合观测事件.在SAR弧的磁层源区,Van Allen Probe B卫星观测到了密度不规则结构,其中存在EMIC波、环电流离子分布和非线性电场结构.联合观测表明:该区域中的环电流离子分布通过库伦碰撞产生的热流通量足以驱动SAR弧,热流通量受到密度不规则结构的调制,形成空间上的小尺度分布,环电流离子中几keV的质子和几十keV的氧离子对这个过程起主导作用;此外,位于等离子体层顶密度不规则结构的低密度区的非线性结构电场引起的低能电子沉降可能是造成这次SAR弧非常明亮的原因.展开更多
基金the National Natural Science Foundation of China(grant 19972072)Project of the Open Laboratory of Continental Geodynamics of the Ministry of Land and Resources(grant 9812) Stat Project 305 rgrant 96—915—06—04).
文摘Continent-continent collision is the most important driving mechanism for the occurrence of various geological processes in the continental lithosphere. How to recognize and determine continent-continent collision, especially its four-dimensional temporal-spatial evolution, is a subject that geological communities have long been concerned about and studied. Continent-continent collision is mainly manifested by strong underthrusting (subduction) of the underlying block along an intracontinental subduction zone and continuous obduction (thrusting propagation) of the overlying block along the intracontinental subduction zone, the occurrence of a basin-range tectonic framework in a direction perpendicular to the subduction zone and the flexure and disruption of the Moho. On the basis of numerical modeling, the authors discuss in detail the couplings between various amounts and rates of displacement caused by basin subsidence, mountain uplift and Moho updoming and downflexure during obduction (thrusting propagation) and subduction and the migration pattern of basin centers. They are probably indications or criteria for judgment or determination of continent-continent collision.
基金supported by the National Natural Science Foundation of China (40404011, 40774051, 49734230)the basic outlay of scientific research work from Ministry of Science and Technology of the People’s Republic of China in 2007 and 2008 (J0707, J0803)+2 种基金Sino-American collaboration project from Ministry of Science and Technology of the People’s Republic of China (2006DFA21340)China National Probing Project (SinoProbe-02)Open Fund of Geo-detection Laboratory, Ministry of Education of China, and China University of Geosciences (No. GDL0602)
文摘Along the western Kunlun-Tarim-Tianshan geoscience transect in the northwestern China, an integrated geophysical investigation was carried out. Owing to the abominable natural conditions there, the sounding profile could not cross the whole transect, consequentially, a variety of velocity structures in the transverse and vertical orientations beneath the whole transect were not obtained, such as the case within the western Kunlun orogenic belt. To supply a gap of deep seismic soundings within the western Kunlun orogenic belt, we used the Bouguer gravity anomaly data and the relationship between the compressive wave and the density to obtain the density structure of the crust beneath the western Kunlun and the southern Tarim basin by a forward fitting of gravity anomalies within the two-dimensional polygonal model of uniform medium. The crust of the Tarim basin with a rigid basement was like an asymmetrical arc, whose surface feature was the Bachu uplift in the middle of the Tarim basin. Beneath the conjoint area between the Tarim basin and the western Kunlun belt, there was a V-shape structure located just up to the top of the uplifted Moho. The multi-seismological structures jointly revealed that the face-to-face continent-continent collision beneath the western Kunlun is a new structural style within the continent-continent collision zone, which is a real model proved by the numerical modeling.
文摘SAR弧的磁层源区对应环电流与等离子体层顶重叠区域,而等离子体层顶常常观测到密度不规则结构.之前还没有暴时等离子体层顶密度不规则结构对SAR弧调制的观测报道.本文报道了地基成像和磁层、电离层卫星对2013年10月9日磁暴恢复相期间发生的SAR弧的联合观测事件.在SAR弧的磁层源区,Van Allen Probe B卫星观测到了密度不规则结构,其中存在EMIC波、环电流离子分布和非线性电场结构.联合观测表明:该区域中的环电流离子分布通过库伦碰撞产生的热流通量足以驱动SAR弧,热流通量受到密度不规则结构的调制,形成空间上的小尺度分布,环电流离子中几keV的质子和几十keV的氧离子对这个过程起主导作用;此外,位于等离子体层顶密度不规则结构的低密度区的非线性结构电场引起的低能电子沉降可能是造成这次SAR弧非常明亮的原因.
