P-wave tomography and relation between shallow and deep structures beneath the Songliao basin

We selected relative travel-time residuals from teleseismic waveform data using the waveform correction method and imaged the P wave velocity structure beneath Northeast China. In combination with other geophysical data, we discussed the relation between the shallow and deep structures of the area. The results show that there is a primary high-velocity zone with some high- and low-ve- locity distribution characters beneath the Songliao basin. The low-velocity anomalies may extend down to the upper mantle, and may be the result of material upwelling. The low-velocity anomaly beneath the southern part of the Songliao basin is connected to those beneath the Chang- baishan and A＇ershan volcanic areas. It may be an upwelling channel from the mantle beneath the Songliao basin and adjacent area. This finding indicates the Songliao basin was a result of asthenospheric upwelling caused by subduction of the Pacific plate under the Eurasian plate.

Coupling Effects on Gold Mineralization of Deep and Shallow Structures in the Northwestern Jiaodong Peninsula, Eastern China

For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.

Study on coupling between deep and shallow structures of Xingtai area and some significant questions

In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.

Study on relationship between deep and shallow structures along north boundary fault of Yanqing-Fanshan basin

Based on the results of surface geology, shallow and deep seismic survey, features of micro-earthquake activity along the north boundary fault of Yanqing-Fanshan sub-basin and their relationship with the surface active faults and the deep-seated crustal structure are analyzed using the recordings from the high-resolution digital seismic network. The focal mechanism solutions of micro-earthquakes, whose locations are precisely determined by the seismic network, have confirmed the structural characteristics to be the rotational planar normal fault and demon-strated the surface traces of the north boundary fault of Yanqing-Fanshan sub-basin. By using the digital recordings of earthquakes with the high resolutions and analyzing the mechanism solutions, our study has revealed the rela-tionship between the geological phenomena in the shallow and deep structures in Yanqing-Huailai basin and the transition features from the brittle to ductile deformation with the crustal depth.

Research on the Characteristics of Deep and Shallow Structures in Shenyang City and Their Relationship with Seismic Activities

Deep and shallow tectonic data in Shenyang and its relationship with seismic activity shows that the NE trending faults developed on the surface control the formation and development of the fault-uplift and fault-depression. The uplift and depression of the bedrock at a depth of 7km underground are＇consistent with the surface structure. 12 planar listric normal faults have developed above a depth of 18km -20km and two deep faults have developed in the lower crust. Because of the deep incision and new activities, the surface Wanggangpu-Xinehengzi fault and Yongle-Qingshuitai fault, which correspond to the deep F3 fault and F6 fault, might be related to seismic activity in Shenyang.

Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties.Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration.One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization.This paper reviews the principles of hydrodynamics of mineralization,especially the nature of relationships between mineralization and structures,and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems.Three categories of mineralization systems were examined,i.e.,magmatic-hydrothermal systems,structurally controlled hydrothermal systems with uncertain fluid sources,and hydrothermal systems associated with sedimentary basins.The implications for deep mineral exploration,including potentials for new mineral resources at depth,favorable locations for mineralization,as well as uncertainties,are discussed.

The heterogeneous characteristics of crust-mantle structures and the seismic activities in the northwest Beijing region

In this paper, the abnormal characteristics of the crustal structures in the seismic active region, Yanqing-Huailai and Zhangbei-Shangyi, are obtained by means of comprehensively interpreting and studying the data of deep seis- mic sounding profiles passing through the northwestern part of Zhangjiakou-Bohai seismic zone. The results show that the fluctuation of crystalline basement in the study region is obvious and that there exist considerable differ- ences in depth in different geological units. The locally abrupt variation of crystalline basement depths may be regarded as a mark of existence of crystalline basement faults. These crystalline basement faults and deep crustal faults provide a pass for the magma upwelling, resulting in the strong inhomogeneity of crustal structures. These phenomena of the complex seismic reflected waves and locally discontinuous reflection zones with different en- ergy indicate that the intensive squeeze and deformation of crust took place, which have led to the complex crustal structures and offered the dynamic source for the earthquake occurrence in this region. The low velocity bodies in different depths of crust and the local interface C1 in Zhangbei-Shangyi region may result from repeated magmatic activities. The certain stress accumulation in the brittle upper crust can cause the occurrence of earthquake under the action of local tectonic activity.

Seismotectonic Study on the West Part of the Interaction Zone Between Southern Tianshan and Northern Tarim

The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles.

受邻近开挖影响的浅基础砌体结构三阶段分析法

浅基础砌体结构的材料力学行为和受力体系决定了其对变形极其敏感,尤其是邻近深基坑工程施工时,需在基坑开挖前对影响范围内的砌体结构建筑进行安全评价。鉴于此,提出一种用于受邻近深开挖影响的浅基础砌体结构变形和损伤分析的三阶段分析法。三阶段分析法依托于数值模拟,根据影响因子权重依次构建地基结构模型、荷载结构模型和分离式砌体模型,在减少计算量的同时,尽可能准确预测砌体结构的变形和损伤风险。本文依托杭州市某深基坑工程,采用该分析法对受深开挖影响的砌体结构建筑进行深入分析,结合实测数据验证计算结果。结果表明,三阶段分析法能较好地反映因基坑开挖引起的周边建筑物的变形和表观损伤情况,在评价浅基础砌体结构损伤、预测结构变形等方面有较好的适用性,可为基坑开挖与周边建筑物相互影响的超前预测提供一种思路。

浅埂-深潭区的流场结构对树叶运动特性的影响研究

研究浅埂-深潭中复杂的流场结构及其对树叶运动特性的影响对生态航道建设具有重要意义。为研究不同形式的浅埂-深潭区段的流场结构及树叶的运动特性,结合长江上游朝天门至涪陵河段浅埂-深潭生境营造方案,通过调整浅埂长度(L)改变河宽缩窄率(N)、浅埂间距(S)以及浅埂淹没程度(Z)设计水槽试验,对比分析其流速场结构以及树叶的轨迹特征。研究结果表明:①回流区特征和流速梯度是影响树叶运动的关键因子,树叶大多在流速梯度较大的区域上运动。②当浅埂处于未淹没状态时,上游深潭的回流区范围以及平均流速比下游深潭大,回流区长宽比为3∶1最有利于树叶进入深潭。③随着河宽缩窄率的增大,浅埂头部附近流域的流速梯度增大,树叶进入深潭的概率逐渐增大。④当浅埂被淹没后,深潭区难以形成回流区以及浅埂顶部发生的跌水过程均不易使未浸泡的树叶保留在深潭内。⑤以树叶进入深潭的概率作为浅埂-深潭生境评价的重要指标,提出N=0.33,S=3 L作为浅埂-深潭生境的最优方案,可适当增大浅埂的高度(D),有利于树叶等有机漂浮物的富集。研究成果可为后续研究浅埂-深潭型鱼类生境营造方案提供科学参考。

双侧基坑紧邻地铁车站施工安全影响和保护对策

以南京宁句城际线某车站两侧紧邻的3#、4#基坑为例,运用MADIS/GTS三维有限元软件分析模型研究3#(深)、4#(浅)基坑双侧不同施工时序下地铁结构位移变化规律。研究表明:地铁结构主要发生面向基坑一侧的水平位移;3#基坑主要影响车站主体东侧和1号风亭;4#基坑主要影响车站主体西侧和1号出入口。综合来说,先施工3#深基坑后施工4#浅基坑相比先施工4#浅基坑后施工3#深基坑对地铁车站、附属(风亭、出入口)产生的水平位移大,3#、4#基坑同时施工对地铁车站、附属影响介于3#、4#先后施工之间。

深水油气开采风险评估及安全控制技术进展与发展建议

深水油气资源是国际油气勘探开发的主战场和技术争夺的制高点,南海深水油气资源丰富,但面临更恶劣的深水海洋环境、更复杂的浅层地质灾害、更具挑战的深层地质条件和更苛刻的深水油气开采工况,致灾机理复杂,作业风险极高,探索适用于南海深水油气开采的风险评估及安全控制技术体系,是确保深水油气安全高效开采的关键。针对深水油气开采面临的海洋环境、浅层灾害、深层地质、气井开采等四大挑战,通过技术攻关与工程实践,形成了具有南海特色的深水油气开采风险评估基础理论及关键技术体系,包括深水海洋环境风险评估与控制、深水浅层地质灾害预测与控制、深水钻井井控与应急救援、深水油气开采设施安全检测及监测等关键技术,指出超深水、深水深层、深远海等待勘探领域亟需解决复杂井作业风险高、关键核心装备和工程软件依赖进口、深水安全环保要求极高、数字智能化转型迫切等重大问题,提出了持续追求本质安全、推进关键装备和工程软件的国产化、增强高效风险防控与应急能力、智能化保安全等发展建议,以进一步推动深水油气开采风险评估及安全控制技术的发展与进步,实现南海深水油气安全、高效、自主、可控开发。

双巷掘进留小煤柱护巷下深浅孔组合爆破卸压技术研究

为防控双巷掘进留小煤柱护巷布置下邻空巷道大变形及强矿压灾害,以赵庄煤业为工程背景,提出了深浅孔组合爆破卸压技术。通过开展小煤柱护巷顶板力学结构和深浅孔聚能组合爆破机制研究,揭示了邻空巷道挠度和采空区顶板L的关联性,并确定顶板倾向断裂位置,明晰深浅孔组合双层位爆破消冲护巷的作用机制和深浅孔组合导向力学作用机理;并通过铰接块体等理论计算和现场试验确定了爆破方案参数。工程实践表明:深浅孔组合爆破卸压技术能够弱化坚硬复合顶板介质的储能蓄力属性,优化采空区边界顶板三角块结构,同等尺度下顶板积聚能量密度降低4000 J左右;1313工作面回采后采空区边界顶板及时垮塌,降低顶板对煤柱挤压作用,煤柱不同深度测点处应力集中系数分别为1.38和1.29,应力集中程度明显减小;邻空巷道扇形窥视结果表明低位岩层裂隙发育明显,高位岩层呈现逐步损伤、断裂状态,在顶板倾向上组合爆破能够缩减岩块B悬顶长度,破坏基本顶铰接结构,减弱岩块的回转下沉作用;13163巷顶底板、两帮最大移近量分别为440 mm和205 mm,爆破措施有效抑制了巷道变形,且未发生片帮冒顶等动力现象,达到了深浅孔组合爆破施工目的。

银川断陷盆地地壳结构与构造的地震学证据

通过跨银川断陷盆地,完成了一条长68.9 km的高分辨深地震反射探测剖面,首次获得了银川盆地地壳精细结构、地堑型断陷盆地深部断裂系(黄河断裂、银川断裂、贺兰山东麓断裂)特征及深浅构造关系.结果表明:银川断陷盆地上地壳为双程走时8 s(深度约20km)反射面以上的区域,上地壳上部地层层位丰富,地层分段连续性较好,上地壳下部地层分层特征不明显,地质构造简单;下地壳(8～13 s)反射能量较弱,反射同相轴不明显;下地壳下部壳幔过渡带(13 s附近)由一组能量较强、持续时间较长(1.5 s)的反射波组组成,厚度约4.5 km.芦花台断裂、银川断裂分别于12～12.5 km、18～19 km深处交汇于贺兰山东麓断裂,贺兰山东麓断裂于28～29 km深处交汇于黄河断裂,黄河断裂为错断Moho面的深大断裂,银川地堑为以黄河断裂为主,其他断裂为辅组合而成的负花状构造.根据贺兰山东麓断裂和银川断裂的相互关系,认为贺兰山东麓断裂对1739年平罗银川8级地震起主要控制作用.

深地震反射剖面揭示的天山北缘乌鲁木齐坳陷地壳结构和构造

已有活动构造研究结果表明，天山北缘具有典型的大陆内部活动构造特征，表现为多排平行山体的背斜和逆断裂.为了研究乌鲁木齐坳陷区的地壳细结构、主要断裂展布和深、浅构造关系，2004年底，在乌鲁木齐西部的天山与准噶尔盆地之间的过渡带上，完成了一条近SN向的长度为78 km的深地震反射探测剖面.结果表明，该区地壳以双程走时9-10.5 s左右的强反射带为界分为上地壳和下地壳，上地壳厚约26-28 km，下地壳厚约23-25 km.双程走时5 s以上，反射层位丰富，构造形态清晰，且在剖面横向上具有明显不同的构造特征；在西山以南的区域，为一系列近东西向展布、南北向排列的逆冲背斜构造和一组自南向北逆冲的断裂，它们在深部均受到滑脱带的控制；在西山和王家沟一带，为一套向北陡倾的反射层系和一组沿层间滑动的断裂；剖面北部显示出了典型的沉积盆地图像，沉积盆地最深处约为10-12 km.双程走时6-9 s之间，为一些延续长度较短、反射能量较弱、且无规律可寻的凌乱反射，表明这部分地壳结构具有明显的“反射透明”性.Moho过渡带出现的时间位于双程走时14-17 s，对应壳幔过渡带厚度约为9-10 km.本区Moho面自北向南逐渐加深，剖面北部其深度约为50-52 km，在靠近北天山附近，其深度约为54-55 km.在剖面中部的西山附近，上、下地壳分界面反射和Moho过渡带反射变得模糊，且浅部地层还出现隆起和褶皱，推测与准噶尔盆地和天山的挤压过程有关.

板内地震过程的三层次构造模式

地震的本质是一个能量长期积累和突发释放的地质过程。在板内地震特征分析的基础上,我们提出板内地震的三层次构造模式——软流圈上隆的深部构造、中地壳韧性流变层(低速高导层)及其上、下的强硬层组成的中部三明治构造和上地壳浅表脆性断裂构造。软流圈上隆使岩石圈减薄并为震源提供热能和机械能,提升地震三明治构造中韧性流变层的温度,且降低其粘度,相应地加大了高导层与高阻层的能干差,使得热能和机械能引起的应变能在两种不同流变性质介质边界附近强烈集中。三明治构造上面脆性断裂加速了应力集中,当活动断层达到三明治构造边界,即可触发地震的发生,引起应变能、热能的突然释放。基于以上模式,我们初步设计了对三层次构造信息的地震监测系统。

深度学习的研究与发展

针对以往浅层学习对特征表达能力不足和特征维度过多导致的维数灾难等现象,深度学习通过所特有的层次结构和其能够从低等级特征中提取高等级特征很好地解决了这些问题,并给人工智能带来了新的希望.首先介绍了深度学习的发展历程,并介绍了基于restricted boltzmann machines(RBM)、auto encoder(AE)和convolutional neural networks(CNN)的deep belief networks(DBN)、deep boltzmann machine(DBM)和stacked auto encoders(SAE)等深度模型.其次,对近几年深度学习在语音识别、计算机视觉、自然语言处理以及信息检索等方面的应用的介绍,说明了深度学习结构在相比较于其他结构的优越性和在不同任务上更好的适应性.最后通过对现有的深度学习在在线学习能力、大数据上和深度结构模型的改进上的思考和总结,展望了今后深度学习的发展方向.

天山中段的深浅构造特征

天山起源于古生代的陆-陆碰撞作用,又经历了中新生代的典型陆内造山过程,其深浅构造结构和活动性一直是众多学者关注的热点。文中通过多种地球物理探测和综合地质构造分析, 以地学断面形式对其深浅构造进行填图,揭示了天山中段复杂的深浅构造特色。结果表明:沿古生代的陆-陆碰撞缝合带两侧分别呈现出主要构造地质单元由老到新的对称性,并伴有相应深部结构的复杂性,反映了碰撞过程及后期的构造演化特点;天山中部的上地幔顶部存在厚近 10km、宽近 200km、几乎涵盖整个天山的低速高导层,可能是中新生代以来天山的陆内再造山作用引起的壳幔拆沉作用形成的残留下地壳。

北京地区地壳精细结构的深地震反射剖面探测研究

长度100 km、NW向穿过三河-平谷8.0级地震区和北京地区主要断裂构造的深地震反射剖面,揭示了该区地壳精细结构图像和断裂的深浅构造特征.结果表明,该区地壳以TWT6-7 s左右的强反射带为界分为上地壳和下地壳,上地壳厚约18-21 km,下地壳厚约13-1 5 km.剖面TWT3-4s以上,反射层位丰富,构造形态清晰,且在剖面上具有明显不同的构造特征;在三河平谷地震区以西,剖面揭示了2-3组反射能量较强的反射震相和一系列错断基底面的断裂,在三河-平谷地震区以东,为一套自东向西倾伏的密集强反射层,这套反射具有典型的沉积盆地特征,盆地最深处约为8-9 km.剖面揭示的地壳深断裂倾角陡直,该断裂切割、扰动了下地壳物质和壳幔过渡带,向上延伸至上地壳,将地壳深部构造与浅部断裂联系在一起,构成了该区最主要的深浅构造特征.

六安-霍山地震危险区地震活动和地震构造

运用深、浅部构造对比方法与宏、微观构造解析技术 ,结合历史地震资料分析结果 ,探讨了中强震过渡区地震构造环境的研究途径。圈定出六安 -霍山地震危险区。对该地震危险区进行立体综合剖析 ,推演出未来中强震发生的空间部位 ,并预测了研究区未来可能发生地震的震源深度、震级。