华南及其相邻边缘海域一些重要断裂的地球物理证据

通过对华南及其相邻的边缘海域的布格重力异常和磁力数据的处理和分析，利用水平方向导数、小波变换及典型剖面反演的共同结果，在研究区中分辨出方向各异的主要断裂共39条，根据重磁异常特征并结合层析成像结果分析了研究区内断裂的分布与延伸，特别对红河断裂带等重要断裂进行了重点讨论，并探讨了它们的延伸及与周边各地质单元之间的关系。     

扬子块体两侧造山带地壳推覆的地球物理证据及其地质意义

基于深部地球物理探测结果建立的青藏高原东缘-江南造山带的地壳结构,发现扬子块体在NW向受到来自青藏高原东缘物质的逆冲推覆,在SE向受到来自江南造山带物质的逆冲推覆.这些推覆作用控制了川西-江南雪峰造山带西部地壳构造.青藏高原向东挤出的物质,在龙门山断裂带附近遇到坚硬四川盆地的阻挡,以上、中地壳的向上逆冲推覆,下地壳插入到四川盆地之下和扬子块体内地壳的褶皱、缩短、增厚方式被吸收,形成熊坡、龙泉山构造带,造成浦江-成都-德阳断裂、龙泉山西坡断裂的NW向逆冲.这些结果回答了青藏高原东向挤出物质的去向问题.总之,扬子块体两侧受到造山带地壳逆冲推覆的发现,为研究华南地区的陆内造山机制,恢复构造演化历史和青藏高原侧向挤出的运动学过程开阔了视野.     

强化第二深度空间金属矿产资源探查,加速发展地球物理勘探新技术与仪器设备的研制及产业化

中国正处在快速工业化和经济腾飞的前夜,必须有大量各类金属矿产资源的支撵,当今国内却供给不足.供需矛盾日益尖锐,导致了对外依存度的不断增长.本文从这一前提和解决的途径出发,分析了金属矿产资源形成与聚集的深层过程和动力学响应、地壳深处金属矿产资源探查的科学依据与例证、地球物理方法和技术支撑.据此提出:(1)当今国家所公布的资源量系指第一深度空间(0～500m)找矿、勘探和开发的资源量,尚不能完全表征全国金属矿产资源量的全部;(2)实施第二深度空间(500～2000m)金属矿产资源的找矿、勘探和开发已迫不及待;(3)在深部金属矿产资源的探查和开发中,必须依靠新的认识和新的理念,采用先进的、高精度的地球物理探测方法和技术,并建立起有自主特色的深部矿产资源探查理论、方法和技术体系.(4)引进技术不等于引进创新思维,更不等于引进创新能力;(5)加速发展和研究地球物理勘探新技术与仪器设备,并逐步产业化.     

Suspended microplastics in the surface water of the Yangtze Estuary System,China: First observations on occurrence,distribution

Levels of microplastics (MPs) in China are completely unknown. This study characterizes suspended MPs quantitatively and qualitatively for the Yangtze Estuary and East China Sea. MPs were extracted via a floatation method. MPs were counted and categorized according to shape and size under a stereomicroscope. The MP densities were 4137.3 ± 2461.5 and 0.167 ± 0.138 n/m³, respectively, in the estuarine and the sea samples. Plastic abundances varied significantly in the estuary. Higher densities in three sea trawls confirmed that rivers were the important sources of MP to the marine environment. Plastic particles (>5 mm) were observed with a maximum size of 12.46 mm, but MPs (0.5–5 mm) constituted more than 90% by number of items. The most frequent geometries were fibres, followed by granules and films. Plastic spherules occurred sparsely. Transparent and coloured plastics comprised the majority of the particles. This study provides clues in understanding the fate and potential sources of MPs.     

长江下游—南黄海地震带地震活动性研究

长江下游—南黄海地震带位于华北地震区东南部, 带内地震主要受长江下游和南黄海海域内一系列断裂的控制, 以中强地震活动为主, 是地震活动较强的地区。 本文充分利用该带最新的区域地震台网资料, 历史地震复核资料以及地震构造等资料, 统计和计算了b值、 V₄和中小地震能量密度值, 探讨了带内b值空间分布与历史强震、 中小地震能量密度值空间分布的关系, 进一步研究了长江下游—南黄海地震带的地震活动性特征。 通过本文的研究, 获得了长江下游—南黄海地震带的地震活动性参数, 为概率危险性分析提供计算参数; 探讨了该带未来百年地震发展趋势, 初步判定了该带潜在地震危险区, 为地震活动中长期预测提供参考依据和方法; 研究结果对地震区划、 工程场地地震安全性评价、 地震活动中长期预测均有重要意义。     

Geophysical evidence for thrusting of crustal materials from orogenic belts over both sides of the Yangtze Block and its geological significance

Based on deep geophysical detections, we have reconstructed the crustal structure from the eastern margin of the Tibetan Plateau to the Jiangnan-Xuefeng orogenic belt. The results suggest that the Yangtze Block was overthrusted by crustal materials in its NW direction from the eastern Tibetan Plateau but in its SE direction from the Jiangnan orogen. These overthrusting effects control the crustal structure from the western Sichuan to the western area of the Jiangnan orogen-Xuefeng orogenic belt. The eastward extruded materials from the eastern Tibetan Plateau were blocked by the rigid basement in the Sichuan Basin, where upper-middle crust was overthrusted whereas the lower crust was underthrusted beneath the Sichuan Basin. The underthrusted unit was absorbed by crustal folding, shortening and thickening in the Yangtze Block, forming the Xiongpo and Longquan Mountains tectonic belts and resulting in the NW-directed thrusting of the Pujiang-Chengdu-Deyang fault, and the western hillsiden fault in the Longquan Mountain. These results provide resolution to the controversy where the eastward extrusion material from the Qinghai-Tibet Plateau had gone. Overall, that Yangtze Block was subjected to thrusting of the crustal materials from the orogenic belts over its both sides. This finding has implications for the study of the intracontinental orogenic mechanism in South China, the reconstruction of tectonic evolutionary history and the kinematics processes during the lateral extrusion of the Tibet Plateau.     

长江中下游成矿带中段岩石圈电性结构研究

长江中下游成矿带位于大别造山带、长江中下游凹陷、江南隆起带等大地构造单元结合部位,通过在研究区内布设两条首尾相接共计150 km长的大地电磁剖面,获得了50 km以浅岩石圈尺度的电性分布.长江中下游地区中段地下电性结构显示出在地下10 km和30 km处分别存在明显的圈层结构,以此认为现今横向稳定的"电莫霍"反映了研究区经历燕山期陆内构造-岩浆活动后已基本上完成壳幔重新平衡;而分隔大地构造单元的郯庐断裂带、长江断裂带以及江南断裂带在电性上具有特征的梯度显现,在印支造山期后的引张背景下,断裂带成为强伸展活动带与控制了燕山期大范围的陆内岩浆活动;高导地幔的局域性存在以及从北向南地幔导电性的变化反映了在经受深部动力学过程中处于不同大地构造部位的地幔所遭受的不同类型的改造以及地幔深部的构造极性.     

Yangtze- and Taiwan-derived sediments on the inner shelf of East China Sea

X-ray diffraction (XRD) mineralogical and grain-size analyses indicate that inner continental shelf sediments in the East China Sea (ECS) represent a unique mixing of clays derived from the Yangtze River and silts/sands from small western Taiwanese rivers. Taiwanese (e.g., Choshui) clays (<2 μm) display no smectite but the best illite crystallinity and are only distributed along southeastern Taiwan Strait. Both Yangtze and Taiwanese river clays are illite-dominated, but the poor illite crystallinity and the presence of smectite and kaolinite indicate that Taiwan Strait clays are mainly Yangtze-dominated. In contrast, medium silts (20–35 μm) and very fine sands (63–90 μm) in the Taiwan Strait are characterized by low feldspar/quartz, low K-feldspar/plagioclase and high kaolinite/quartz, indicating their provenance from Taiwanese rivers. Taiwanese silts and sands are introduced primarily by the way of typhoon-derived floods and transported northward by the Taiwan Warm Current during summer–fall months. Yangtze clays, in contrast, are widely dispersed southward about 1000 km to the western Taiwan Strait, transported by the China Coastal Current during winter–spring months. Since most Taiwan Strait samples were collected in May 2006, clay results in this paper might only represent the winter–spring pattern of the dispersal of Yangtze sediments.     

Temporal and spatial variations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the East China Sea and the Yellow Sea

Temporal and spatial distributions of dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) were determined in the East China Sea and the Yellow Sea during June-July, 2006 and January-February, 2007. The concentrations of DMS and total DMSP in surface water in the study area were 5.64 (1.79-12.24) and 28.25 (13.98-44.93) nmol L⁻¹ in summer, and were 1.79 (1.02-3.51) and 11.01 (6.90-17.98) nmol L⁻¹ in winter, respectively. The distributions of DMS and DMSP in the study area were obviously influenced by the Yangtze River effluent and the Kuroshio water. Even under highly variable hydrographic conditions, a significant relationship was observed between DMS and chlorophyll a concentrations in summer as well as in winter, suggesting that phytoplankton biomass might play an important role in controlling DMS distribution in the study area. The summer ratios of DMS/chlorophyll a and DMSP/chlorophyll a were approximately twofold higher than winter values, corresponding with the temporal variation in phytoplankton community structure between summer and winter. The sea-to-air fluxes of DMS were estimated to be 5.32 and 11.92 μmol m⁻² d⁻¹ using the equations of Liss and Merlivat (1986) and Wanninkhof (1992), respectively.     

Effects of the Changjiang river discharge on sea surface warming in the Yellow and East China Seas in summer

This study explores the effects of the Changjiang (also called the Yangtze River) river discharge (CRD) on the density stratifications and associated sea surface temperature (SST) changes using a global ocean general circulation model with regional focus on the Yellow and East China Seas (YECS). It is found that CRD increases the SST in summer through a barrier layer (BL) formation that tends to enhance stratification at the mixed layer base, and thus reduces both vertical mixing and entrainment. This process is effective, particularly in August, after the CRD reaches its maximum in July. The SST difference between the composites of flood and drought years confirms that the surface warming is related to surface freshening by the CRD. This result suggests that the BL induced by the CRD is an important contributor to the surface heat budget in the YECS.     

湘西沅麻盆地早白垩世红层古地磁学研究及其对川东褶皱带新生代构造变形的指示

川东褶皱带作为华南板块中部的"侏罗山式"褶皱,开始形成于晚古生代.自白垩纪晚期开始,受太平洋板块和印度板块对欧亚大陆挤压的影响,这一构造带乃至华南板块中部又叠加了新的构造变形.但是,目前对于川东褶皱带白垩纪以来的构造演化缺乏足够的认识.位于川东褶皱带东侧、雪峰造山带西麓的沅麻盆地形成于早白垩世.晚白垩世以来,沅麻盆地与川东褶皱带处于同一构造应力场中,因此对盆地内早白垩世红层的古地磁研究对于解释川东褶皱带中生代晚期以来的构造演化有着重要的意义.该研究在沅麻盆地早白垩世红层中开展的古地磁学研究获得了可靠的原生剩磁分量：Ds=15.6°,Is=42.9°,k=118.6,α95=2.6°,表明沅麻盆地自早白垩世以来发生了4.1°±3.0°的顺时针构造转动.对川东褶皱带周缘白垩纪古地磁数据所揭示的地壳旋转变形,与断裂和褶皱轴组成的构造线迹变化之间的线性相关性分析,表明川东褶皱带位于齐岳山断裂带东南侧的部分,受印度板块-欧亚大陆、太平洋板块-华南板块间的挤压作用,自晚白垩世以来累积了约50~93 km的右旋错断量.     

西伯利亚板块与华北克拉通碰撞带地电结构及对深部缝合边界的讨论

西伯利亚板块与华北克拉通碰撞导致古亚洲洋闭合,形成了幅员辽阔的中亚造山带,该带内记录了丰富的板块碰撞信息,揭示深部缝合边界对于研究洋-陆俯冲到陆-陆碰撞的深部动力学过程具有重要的科学意义.本文对查干敖包-化德410 km大地电磁测深（MT）剖面数据进行反演,获得二维电性结构,为研究西伯利亚板块与华北克拉通碰撞带深部构造形迹、碰撞边界问题提供地电结构的依据.结合人工反射地震及地质资料获得以下认识：（1）西伯利亚板块与华北克拉通碰撞带地壳存在多组"U"型低阻异常,多对应弧型、倾斜或"鳄鱼嘴"状反射界面.莫霍面存在两处错断现象,并与深部电性梯度带对应.岩石圈地幔除白乃庙岛弧呈低阻块体外,均为高阻块体,这些电性结构特征反映了南北汇聚所形成的构造形迹.（2）碰撞带可分为二连-贺根山和索伦-西拉木伦河两个不同时期的汇聚体系,晚泥盆世-晚石炭世早期形成的二连-贺根山汇聚体系由二连-贺根山增生杂岩带、宝力岛弧地体及断裂带组成,深部缝合边界位于二连浩特.而晚二叠-早三叠的索伦-西拉木伦河汇聚体系由二道井子增生杂岩带和温都尔庙增生杂岩带及断裂带组成,深部缝合边界位于苏尼特右旗.（3）在锡林浩特地区软流圈内部存在高阻异常,可能为俯冲消失的洋壳或碰撞造山后拆离的岩石圈残片.     

中国东北地区剩余重磁异常特征与地质构造及成矿带的关系

在分析中国大陆宏观格架、全国布格重力异常和东北地区1:50万剩余重、磁力异常的基础上,结合东北地质及构造演化史,分析了东北剩余重磁异常特征,并探讨了剩余重磁异常特征与地质构造的关系.总结了与成矿有关的剩余重磁场特征,说明了剩余重磁异常可在刻画地质构造、断裂分布、地层分布及成矿带方面提供重要的参考信息.