S-wave velocity of the crust around Tianshan Mountains inverted from seismic ambient noise tomography

We process ambient noise data from seismic stations deployed in central Asia to determine the crustal shear wave velocity structure beneath the Tianshan Mountians and surrounding area. About 748 inter-station Rayleigh wave empirical Green’s functions have been recovered to estimate the phase velocity dispersions over periods from 6 to 50 s using the image transformation technique. Results show that for short periods (6–20 s), the distribution of Rayleigh wave phase velocities is generally consistent with surface geology, with high velocities corresponding to mountain ranges and low velocities to sedimentary basins. Along two profiles, which trend from NE-SW and NW-SE, the shear wave velocity shows a pair of high velocity anomalies dipping in opposite directions beneath the Tianshan Mountains. At shallow depths, those high velocity anomalies roughly correlate with areas where the mountain front and the surrounding basin are connected. The profiles also show a narrow zone beneath the Tianshan Mountains, which may represent a route for the upwelling from upper mantle. Those observations suggest that the underthrusting of the Tarim Basin and Kazakh Shield combine with the weakness of the crust, which is heated by the upwelling from upper mantle, may play an important role on the reactivation of the Tianshan Mountains associated with the India-Eurasia collision.     

城镇化背景下的南方红壤丘陵区土地覆盖演变——以衡阳盆地为例

土地利用与覆盖（LULC）变化是生态环境演变的主要驱动力。南方丘陵区人口密集,但生态环境脆弱,20世纪90年代快速的城镇化进程产生了急剧环境变化。以衡阳盆地为研究区,以1990年、2000年两个时期的TM遥感影像为主要数据源,采用面向对象分类技术提取植被和建设用地信息,通过反演植被覆盖度,对植被覆盖度进行分级处理,获得了研究区植被覆盖等级分布图,最后,通过对比1990年和2000年建设用地和植被覆盖等级图获得了研究区建设用地和植被覆盖演变信息。研究结果表明：10年内研究区建设用地发生了显著扩展,扩展区域主要集中在衡阳市区周边,扩展区总面积为237.34km2;植被恢复区主要位于研究区北部区域,植被退化区位于研究区西端以及衡南县、祁东县和常宁市等3县市交界的湘江河谷地带以及南部的山区;城镇扩展区内植被退化严重,植被退化面积达到166.84 km2,占城镇扩展面积的比例为70.30%。     

西江南半地堑晚期断裂系统基本特征及其控藏作用

 本文利用地震资料的构造解释和断裂系统的几何学、运动学对西江南半地堑晚期断裂的基本特征进行研究.研究表明,西江南半地堑晚期断裂是在NWW—SEE向张扭应力场作用下发生简单剪切右旋走滑变形形成和发育的.剖面上以负花状构造样式为主;平面上,主要呈NWW走向,断裂组合样式多样,包括平行式、交叉式、斜列式和羽状断层;断裂分布呈现明显分区特征,即晚期断裂主要分布在半地堑的南侧.结合圈闭定型期、油气充注史与晚期断裂活动的相关研究,晚期断裂系统对研究区控藏作用主要体现在3个方面：断裂控圈,即晚期断裂控制了新近系构造圈闭的形成及分布;部分断至古近系文昌组烃源岩内部甚至基底的晚期断裂和长期断裂一起构建了本区垂向优势运移通道,其它晚期断裂对早期油藏的二次调整、油气再运移及再聚集起重要的控制作用;主活动期后晚期断裂较好的侧向封闭性有效地控制了新近系油藏的最终聚集及分布.     

甘肃北山桥湾北花岗岩体的年代学、地球化学及其地质意义

为加深对北山晚古生代构造演化的认识, 选取位于甘肃北山南带、敦煌地块北缘的桥湾北花岗岩体进行年代学、地球化学研究。桥湾北角闪石花岗岩体锆石LA-ICP MS年龄为303.7±2.4 Ma, ε_Hf(t)为-1.2~5.8, ε_Nd(t)相对较高(-0.40~-0.06), (⁸⁷Sr/⁸⁶Sr)_i =(0.704524~0.705062)。 桥湾北花岗岩体K₂O含量为4.09%~5.58%, 属高钾钙碱性岩石, A/CNK值在0.92~1.04之间, 为I型花岗岩; 微量元素较富集LILE, 相对亏损HFSE, 有明显的Nb, Ta负异常。岩体具相对富集的微弱分馏的轻稀土元素, 重稀土元素分馏不明显, 基本没有Eu异常。由Hf, Nd同位素及地球化学特征判断, 桥湾北花岗岩体为壳幔混合成因, 其形式可以是底侵的幔源岩浆再分异, 上升过程中遭受地壳物质混染。根据区域构造背景及岩石学、地球化学特征, 可以认为桥湾北岩体是北山南带后碰撞过程岩浆活动的产物, 反映出在晚石炭世北山地区的碰撞拼贴已经完成。     

南疆三地州双语师资现状调查研究

南疆是新疆推行双语教育最关键的地区,也是制约新疆双语教育发展的"短板"。少数民族双语师资短缺、双语教师质量不高一直是制约双语教育的"瓶颈",再加上新疆各地区双语教育的教学起点不尽相同,教学模式差异较大,造成了南疆少数民族小学整体教育教学水平的不高,进而无法完成提高少数民族整体素质的艰巨任务。     

Deep structure at northern margin of Tarim Basin

In this paper, a 2D velocity structure of the crust and the upper mantle of the northern margin of the Tarim Basin （TB） has been obtained by ray tracing and theoretical seismogram calculation under the condition of 2D lateral inhomogeneous medium using the data of seismic wide angle reflection/refraction profile from Baicheng to Da Qaidam crossing the Kuqa Depression （KD） and Tabei Uplift （TU）. And along the Baicheng to Da Qaidam profile, 4 of the 10 shot points are located in the northern margin of the TB. The results show that the character of the crust is uniform on the whole between the KD and TU, but the depth of the layers, thickness of the crust and the velocity obviously vary along the profile. Thereinto, the variation of the crust thickness mainly occurs in the middle and lower crust. The Moho has an uplifting trend near the Baicheng shot point in KD and Luntai shot point in TU, and the thickness of the crust reduces to 42 km and 47 km in these two areas, respectively. The transition zone between the KD and TU has a thickest crust, up to 52 km. In this transition zone, there are high velocity anoma- lies in the upper crust, and low velocity anomalies in the lower crust, these velocity anomalies zone is near vertical, and the sediment above them is thicker than the other areas. According to the velocity distributions, the profile can be divided into three sections： KD, TU and transition zone between them. Each section has a special velocity structural feature, the form of the crystalline basement and the relationship between the deep structure and the shallow one. The differences of velocity and tectonic between eastern and western profile in the northern margin of the Tarim Basin （NMTB） may suggest different speed and intensity of the subduction from the Tarim basin to the Tianshan orogenic belt （TOB）.     

历史上北方游牧民族与南方农耕民族的民族关系及其规律性

自秦汉中国已形成为统一的多民族国家,民族关系的研究在中国的历史研究中也占据了重要地位。浑然天成的北方游牧民族与南方农耕民族时战时和,在历史长河中互相影响、互相依附,在政治、经济、文化等方面融合发展,独具其特性与规律性。     

太原南郊电网黑启动思路

针对南郊电网全黑的情况,详细分析了电网现状与规划电网,提出了具体的黑启动思路。     

油伴生CO2气的成因及其石油地质意义

以松辽盆地南部油伴生CO2气为研究对象,通过组分分析及碳、氧及氮同位素分析,结合中国已有伴生CO2气的含量及同位素数据,研究油伴生CO2气的成因及其意义.结果表明:中国油伴生气中CO2的含量为0～99.53%,大部分在5%以下;油伴生CO2气的δ13 CcO2值为-15.91‰+6.49‰,集中分布于-13‰～ -4‰,以无机成因气为主;松辽盆地南部油伴生CO2气的含量为1.43% ～54.22%,δ13CcO2值为-5.32‰～ -6.76‰,为幔源-岩浆成因;幔源-岩浆成因油伴生CO2气与气藏中的CO2气成因一致,注入时间一般晚于油气大规模充注时间,CO2充注驱油普遍存在;在幔源-岩浆CO2与油气混合成藏地区(如松辽盆地南部)寻找幔源-岩浆CO2充注驱油成因的次生油气藏将是一个新的勘探思路.     

惠民南部地区油气运移通道组合类型及其成藏作用

根据油气单一运移通道特征,建立惠民凹陷南部地区油气运移通道组合类型,并系统总结其成藏作用.结果表明:惠民凹陷南部地区主要发育连通砂体、断层及不整合3种油气运移通道,形成了砂体—断层—砂体、砂体—断层—不整合和砂体—不整合3种组合类型;这些组合类型不仅控制了油气运移模式,发育反“Z”字型输导运移模式、阶梯状输导运移模式等,而且控制了油气空间分布特征;砂体—断层—不整合型和砂体—不整合型决定曲堤地区油气具有“多层系分布、油气藏类型多样、运移距离远”的特征;单一的砂体—断层—砂体组合类型决定钱官屯地区油气具有“单层系分布、油气藏类型单一、运移距离近”的特点.