青藏高原东北缘祁连山中部精细地壳结构研究

作为一种能够精细揭示地球深部地质结构及构造特征的有效手段,深地震反射剖面技术目前已越来越多地应用于大陆及海洋地壳与岩石圈上地幔的探测中,被国际公认为地球深部探测的先锋技术。以横跨河北雄安新区的深地震反射剖面为研究对象,旨在揭示研究区的地壳结构与构造特征。结果表明：(1) 该地区地壳可分为上地壳和下地壳两部分,上地壳平均厚度约18 km,下地壳平均厚度约16 km,莫霍面平均深度约34 km。(2)上地壳内,结晶基底以上的沉积地层成层性好、地层反射能量强、结构特征复杂,断裂构造较发育、形态各异、错断深度不同、无深大断裂,主要断裂自SE向NW依次为牛东断裂、牛北断裂、容东断裂、容城断裂、容西断裂以及太行山山前断裂。(3)下地壳内,深地震反射剖面西北部和东南部受到不同构造应力作用,西北部和中部相对“透明”,反映雄安新区整体构造较为稳定;东南部存在较强的“叠瓦状”反射特征,反映下地壳横向非均质性和局部活跃的特征。上述研究为雄安新区总体规划与建设和构建万米“透明雄安”基础平台提供了可靠的数据支撑。

     

银川盆地构造发展——深地震反射剖面揭示浅部地质与深部构造的联系

横跨银川盆地北西西向的深地震反射剖面,清晰揭示了银川盆地边界断裂以及整个地壳的结构构造特征,这对研究具活动大陆裂谷性质的银川盆地浅-深构造关系具有重大的意义。贺兰山东麓山前断裂、黄河断裂作为银川盆地的西、东边界断裂,前者为一条缓倾斜、延伸至上、下地壳边界的犁式断裂,而后者则为一条切穿地壳并延伸进入上地幔的深大断裂。根据深地震反射剖面揭示的地壳结构特征,银川盆地浅部结构并非前人认为的"堑中堑"结构,而是表现为由一系列东倾犁式正断层控制的新生代断陷。略微下凹的Moho面几何形态以及厚2~3.2 km的层状强反射带为下地壳最显著的反射特征。Moho面深度与强反射带厚度变化趋势与银川盆地沉积厚度变化趋势几乎一致。本文认为,强反射带的成因可能是由源自地幔的基性岩浆以岩席状的形式底侵进入地壳底部造成的,而这部分形成强反射带的物质可能补偿了因银川盆地断陷而造成的地壳减薄,最终导致银川盆地之下Moho面并未像之前所认为的那样隆起。     

松辽盆地地幔热流的演化特征

本文根据松辽盆地沉积岩层中的放射性元素（Ｕ、Ｔｈ、４０Ｋ）含量以及地震波速，计算了盆地各岩层放射性生热率，然后，采用＂剥层法＂从地表开始，自上而下，由浅入深地扣除盆地在不同演化阶段各岩层提供的热量，从而得出地质年代地幔的热流值，并在此基础上，探讨了地幔热流演化与盆地构造发展的关系。     

Near-vertical seismic reflection image using a novel acquisition technique across the Vrancea Zone and Foscani Basin, south-eastern Carpathians (Romania)

The DACIA PLAN (Danube and Carpathian Integrated Action on Process in the Lithosphere and Neotectonics) deep seismic sounding survey was performed in August–September 2001 in south-eastern Romania, at the same time as the regional deep refraction seismic survey VRANCEA 2001. The main goal of the experiment was to obtain new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basins developed within and adjacent to the seismically-active Vrancea zone, including the Focsani Basin. The seismic reflection line had a WNW–ESE orientation, running from internal East Carpathians units, across the mountainous south-eastern Carpathians, and the foreland Focsani Basin towards the Danube Delta. There were 131 shot points along the profile, with about 1 km spacing, and data were recorded with stand-alone RefTek-125s (also known as “Texans”), supplied by the University Texas at El Paso and the PASSCAL Institute. The entire line was recorded in three deployments, using about 340 receivers in the first deployment and 640 receivers in each of the other two deployments. The resulting deep seismic reflection stacks, processed to 20 s along the entire profile and to 10 s in the eastern Focsani Basin, are presented here. The regional architecture of the latter, interpreted in the context of abundant independent constraint from exploration seismic and subsurface data, is well imaged. Image quality within and beneath the thrust belt is of much poorer quality. Nevertheless, there is good evidence to suggest that a thick (10 km) sedimentary basin having the structure of a graben and of indeterminate age underlies the westernmost part of the Focsani Basin, in the depth range 10–25 km. Most of the crustal depth seismicity observed in the Vrancea zone (as opposed to the more intense upper mantle seismicity) appears to be associated with this sedimentary basin. The sedimentary successions within this basin and other horizons visible further to the west, beneath the Carpathian nappes, suggest that the geometry of the Neogene and recent uplift observed in the Vrancea zone, likely coupled with contemporaneous rapid subsidence in the foreland, is detached from deeper levels of the crust at about 10 km depth. The Moho lies at a depth of about 40 km along the profile, its poor expression in the reflection stack being strengthened by independent estimates from the refraction data. Given the apparent thickness of the (meta)sedimentary supracrustal units, the crystalline crust beneath this area is quite thin (< 20 km) supporting the hypothesis that there may have been delamination of (lower) continental crust in this area involved in the evolution of the seismic Vrancea zone.     

南海北部洋-陆过渡带深部结构与岩石圈破裂过程

洋-陆过渡带是理解大陆岩石圈破裂和海底初始扩张的关键位置,但是在南海北部地区仍然存在关于相关地质过程的诸多疑问.通过近年开展的国际大洋发现计划航次以及深部地质地球物理探测,取得以下4个方面的认识.（1）南海北部的洋-陆边界一般与自由空间重力异常的正-负值过渡位置对应,而更加准确地限定需要结合反射、折射地震资料.稳定大洋岩石圈生成与大陆岩石圈最终破裂之间的洋-陆过渡边界的位置比以往认为的还应往深海盆方向移动.（2）洋-陆过渡带代表了远端带构造作用减弱和岩浆作用逐渐增强的区域.陆坡地壳发育扩张后岩浆底侵、洋-陆过渡带发育同破裂期岩浆喷出结构和侵入反射体.（3）在中生代的古俯冲带弧前区域,新生代的断裂沿着早期的构造开始活动,岩石圈多处发生强烈的共轭韧性剪切作用.随着大陆岩石圈的进一步拉伸减薄,部分靠陆一侧的裂谷中心停止张裂,成为夭折裂谷,以台西南盆地南部凹陷、白云凹陷、西沙海槽为代表,而南海陆缘异常伸展和最终破裂的地方集中在南侧裂谷中心.夭折裂谷下亦发现地幔蛇纹石化,进一步反映了较弱的同破裂岩浆活动.（4）南海初始洋壳的增生沿着大陆边缘走向具有显著的变化,南海东北部洋-陆过渡带下伏地幔明显抬升和部分蛇纹石化,地震纵、横波速度以及折射波衰减特征都支持此观点,反映南海东北部是一个贫岩浆型大陆边缘.未来,南海北部洋-陆过渡带有望成为南海“莫霍钻”的理想备选钻探区.      

松辽盆地徐家围子地区深反射结构及其盆地动力学意义

通过松辽盆地徐家围子地区深反射地震剖面与世界典型深反射剖面对比,以岩石圈流变学模型为基础,结合浅层钻探资料可以发现,松辽盆地与世界典型裂谷盆地有相似的深反射特征,即层状结构十分明显。岩石圈横向分段性是另一个显著特点,由中下地壳挤压"断裂带"和由热流底辟体组成的"岩浆底辟带"分开。下部块段控制上部层状构造体系的形成与演化过程。由此证明,裂谷演化过程中地幔上涌是主要动力。地壳"三明治结构"和热流底辟体的发育表明,盆地不仅有高热流的地质条件,而且深部存在无机物质"储库"与通道。     

Prospective prediction and exploration situation of marine Mesozoic-Paleozoic oil and gas in the South Yellow Sea

The South Yellow Sea Basin is a large sedimentary basin superimposed by the Mesozoic-Paleozoic marine sedimentary basin and the Mesozoic-Cenozoic terrestrial sedimentary basin, where no oil and gas fields have been discovered after exploration for 58 years. After the failure of oil and gas exploration in terrestrial basins, the exploration target of the South Yellow Sea Basin turned to the marine Mesozoic-Paleozoic strata. After more than ten years’ investigation and research, a lot of achievements have been obtained. The latest exploration obtained effective seismic reflection data of deep marine facies by the application of seismic exploration technology characterized by high coverage, abundant low-frequency components and strong energy source for the deep South Yellow Sea Basin. In addition, some wells drilled the Middle-Upper Paleozoic strata, with obvious oil and gas shows discovered in some horizons. The recent petroleum geological research on the South Yellow Sea Basin shows that the structure zoning of the marine residual basin has been redetermined, the basin structure has been defined, and 3 seismic reflection marker layers are traceable and correlatable in the residual thick Middle-Paleozoic strata below the continental Meso-Cenozoic strata in the South Yellow Sea Basin. Based on these, the seismic sequence of the marine sedimentary strata was established. According to the avaliable oil and gas exploration and research, the marine Mesozoic-Paleozoic oil and gas prospects of the South Yellow Sea were predicted as follows. (1) The South Yellow Sea Basin has the same sedimentary formation and evolution history during the sedimentary period of the Middle-Paleozoic marine basin with the Sichuan Basin. (2) There are 3 regional high-quality source rocks. (3) The carbonate and clastic reservoirs are developed in the Mesozoic-Paleozoic strata. (4) The three source-reservoir-cap assemblages are relatively intact. (5) The Laoshan Uplift is a prospect area for the Lower Paleozoic oil and gas, and the Wunansha Uplift is one for the marine Upper Paleozoic oil and gas. (6) The Gaoshi stable zone in the Laoshan Uplift is a favorable zone. (7) The marine Mesozoic-Paleozoic strata in the South Yellow Sea Basin has the geological conditions required to form large oil and gas fields, with remarkable oil and gas resources prospect. An urgent problem to be addressed now within the South Yellow Sea Basin is to drill parametric wells for the Lower Paleozoic strata as the target, to establish the complete stratigraphic sequence since the Paleozoic period, to obtain resource evaluation parameters, and to realize the strategic discovery and achieve breakthrough in oil and gas exploration understanding.©2019 China Geology Editorial Office.     

Role of the Wide-angle OBS Seismic Exploration in the Research of Marine Sedimentary Basin

Marine sedimentary basin is an important tectonic unit in the earth, and the evolution of marine sedimentary basin involves a series of the coupling and evolution of geodynamic mechanism such as the crust-mantle, the lithosphere-asthenosphere, the strata-fluid deposition. Therefore, the study of marine sedimentary basin dynamics includes deep structure state of earth, material composition and regional tectonic evolution, and also internal structure, tectonic characteristics and pore fluid characteristics strata of the basin. Wide angle Ocean Bottom Seismometer (OBS) seismic exploration is a marine geophysical survey method originated and developed since 1980’s and 1990’s, which has the advantages of strong penetration capability, high seismic imaging precision and reception of both P-wave and S-wave, and playing an increasing significant role in the research of marine sedimentary basin at the aspect of regional tectonic evolution, internal structure and pore fluid development characteristics of strata in recent years. In the study of passive continental margin, the crustal structure acquired from wide angle OBS seismic data provides the direct evidence that divides the passive continental margins into magma-poor and magma-dominated ones, and the degree of thinning and spatial variation characteristics of crust provide constraints for dynamics simulations of tectonic evolution in marine sedimentary basin. In the study of the structure features of basin, wide angle OBS seismic exploration fills in gaps at the aspect of investigation depth and complex geological structure in conventional multi-channel seismic survey, and acquires overpressure distribution status of basin according to the velocity structure characteristics of strata, and then infer the basin sedimentation velocity and pore fluid characteristics. In the study of internal fluid system in marine sedimentary basin, it reveals the velocity structure of natural gas hydrate reservoir through the analysis and processing of wide angle OBS seismic data, and calculates the thickness of natural gas hydrate reservoir and the content of hydrate and free gas in pore based on the velocity variation. Of course, the future wide angle OBS seismic exploration in the aspect of dynamic evolution and mechanism research in marine sedimentary basin will play a more important role with the development of marine seismic exploration technology, the improvement of data processing and instrument parameters.     

Lithospheric structure and dynamic processes of the Tianshan orogenic belt and the Junggar basin

Located at the center of the Eurasian continent and accommodating as much as 44% of the present crustal shortening between India and Siberia, the Tianshan orogenic belt (TOB) is one of the youngest (<20 Ma) and highest (elevation>7000 m) orogenic belts in the world. It provides a natural laboratory for examining the processes of intracontinental deformation. In recent years, wide angle seismic reflection/refraction profiling and magnetotelluric sounding surveys have been carried out along a geoscience transect which extends northeastward from Xayar at the northern margin of the Tarim basin (TB), through the Tianshan orogenic belt and the Junggar basin (JB), to Burjing at the southern piedmont of the Altay Mountain. We have also obtained the 2D density structure of the crust and upper mantle of this area by using the Bouguer anomaly data of Northwestern Xinjiang. With these surveys, we attempt to image the 2D velocity and the 2D electric structure of the crust and upper mantle beneath the Tianshan orogenic belt and the Junggar basin. In order to obtain the small-scale structure of the crust–mantle transitional zone of the study area, the wavelet transform method is applied to the seismic wide angle reflection/refraction data. Combining our survey results with heat flow and other geological data, we propose a model that interprets the deep processes beneath the Tianshan orogenic belt and the Junggar basin.Located between the Tarim basin and the Junggar basin, the Tianshan orogenic belt is a block with relatively low velocity, low density, and partially high resistivity. It is tectonically a shortening zone under lateral compression. A detachment exists in the upper crust at the northern margin of the Tarim basin. Its lower part of the upper crust intruded into the lower part of the upper and the middle crust of the Tianshan, near the Korla fault; its middle crust intruded into the lower crust of the Tianshan; and its lower crust and lithospheric mantle subducted into the upper mantle of the Tianshan. In these processes, the mass of the lower crust of the Tarim basin was carried down to the upper mantle beneath the Tianshan, forming a 20-km-thick complex crust–mantle transitional zone composed of seven thin layers with a lower than average velocity. The thrusting and folding of the sedimentary cover, the intrusive layer in the upper and middle crust, and the mass added by the subduction of the Tarim basin into the upper mantle of the Tianshan are probably responsible for the crustal thickening of the Tianshan. Due to the important mass deficiency in the crust and the upper mantle of the Tianshan, buoyancy must occur and lead to rapid ascent of the Tianshan.The episodic tectonic uplift of the Tianshan and tectonic subsidence of the Junggar basin are closely related to the evolution of the Paleozoic, Mesozoic, and Cenozoic Tethys.     

中国大陆科学钻探场址区的地壳速度结构特征

为了深入研究大别—苏鲁超高压变质带的深部结构及空间展布特征, 进一步揭示该超高压变质形成的动力学过程, 在中国大陆科学钻探场址区进行了广角反射/折射地震测深调查.根据广角反射/折射地震测深的资料研究, 建立了中国大陆科学钻探场址区的地壳纵波速度结构.从纵向上来看, 研究区域的地壳结构可划分为上、中、下3层: 上地壳的速度小于6.2 0km/s, 厚10余km; 中地壳的速度为6.4 0km/s, 厚亦为10km左右; 下地壳的速度为6.6 0km/s.地壳厚度为31km左右, 且其地壳的平均速度为6.30km/s.上地壳中的速度倒转指示了超高压变质体在地壳内部的空间分布, 且超高压变质体在大陆科学钻探场址及其附近的下部呈现为一隆起形态.      

Improvements in seismic reflection techniques for studying the lithosphere in Australia

Over the last 25 years the Australian Bureau of Mineral Resources (BMR) has attempted to record seismic reflection data in several parts of Australia to determine if good quality near-vertical reflections could be obtained from the deep crust and upper mantle. Data recorded prior to 1976, using analogue instruments and large shots, did obtain good to fair quality deep events, but the short lengths of the traverses recorded did not allow discrimination between primary reflections and the coherent noise. The high cost of the special effort prevented recording of long traverses, and hence the study of the true nature of the deep reflections. From 1976 onwards, with the advent of digital recording and processing equipment and techniques, it became possible to obtain good quality deep reflection data on long traverses with the parameters such as small charges, short spreads, etc. which are normally used for recording good sedimentary reflections. The recent data allow better identification of reflections and study of their character, and provide a higher resolution picture of the nature and structure of the deep crust and upper mantle, than had been possible before. BMR is, therefore, now recording good deep reflection data on all traverses during normal sedimentary basin surveys, and accumulating the information necessary for studying the evolution of lithosphere in Australia.     

地球深部探测的先锋: 深地震反射方法的发展与应用

深地震反射剖面早已被国际上证实是一种地球深部探测的先锋技术,它利用比石油地震勘探更长的接收排列、更大的激发能量,探测上至地表,下达上地幔的精细结构和构造特征,现已被国内外越来越多地应用于大陆及海洋地壳与岩石圈上地幔探测上。深地震反射剖面技术在揭示地球深部动力学过程,论述大地构造演化,确定盆山耦合关系,推测成矿成藏条件,分析地震灾害等方面取得了丰硕成果。系统地梳理和概括了国内外陆地地区深地震反射剖面技术的研究现状以及典型应用案例。在此基础上,从深地震反射野外数据采集、数据资料处理、剖面地质解译以及多方法联合探测4个方面,对地震反射剖面技术未来发展方向进行了展望。研究认为：在野外采集方面,研发不同激发、接收组合类型的采集技术、提升深地震反射数据采集质量,减少环境破坏,降低经济成本;在数据处理中,继续探究提高深地震反射剖面的信噪比与分辨率,定量监控深地震反射数据处理过程中振幅保真度的相对变化;在资料解译时,将深入挖掘深地震反射剖面的叠前、叠后潜在信息,降低单纯依靠深地震反射振幅解译的非唯一性;在综合研究上,从多学科、多角度、多尺度、多方法上相互补充印证,降低剖面的多解性,提高成果的准确性和可靠度。

     

Deep CMP seismic surveying along the Tatseis-2003 geotraverse across the Volga-Ural petroliferous province

The objective, methods, and main results of deep CMP seismic surveying along the Tatseis-2003 geotraverse are discussed. This geotraverse crosses the Volga-Ural petroliferous province from the northwest to the southeast for more than 1000 km and is linked with the well-known Uralseis-95 geotraverse by an additional profile. The main objective of this surveying was to study the structure of sedimentary cover and the Earth’s crust as a whole in the North Tatar Arch, Kazan-Kazhim Trough, Kotel’nich Arch, and the southeastern Moscow Syneclise in comparison with the petroliferous South Tatar Arch. The applied technology (telemetric stations, powerful vibrators, a 12-km spread, a common midpoint fold of 60, and a recording time of 20 s), the planning of seismic exploration with consideration of the available geological and geophysical information, and special processing of the data—all this provided the high-quality time sections that allowed solution of the geologic problems. The main scientific and applied results of the investigations are establishment of the links between petroleum resource potential of the sedimentary cover and the structure of the Earth’s crust and upper mantle. These data are of basic importance and testify to the considerable role of deep factors in the formation of hydrocarbon fields. After these factors are tested in other regions, the revealed indications may be used in petroleum exploration. The tectonic nature of inclined reflectors in the Earth’s crust and upper mantle is substantiated. It is shown that the near-vertical dynamic anomalies are caused by real geologic bodies. A complex of investigations is proposed for their further interpretation. The deep seismic surveying along the geotraverse fulfilled its task completely. At the same time, the results obtained allow recommending lines of further research and their methods. It would be expedient to perform generalizing scientific research aimed at coordinating the Uralseis-95 and Tatseis-2003 geotraverses in order to develop a common profile from the Urals to the Moscow Syneclise, provide complex interpretation of these data, and integrate the results of the previously performed deep CMP seismic surveying.     

珠江口盆地恩平凹陷恩平组物源体系分析及未来大洋钻探建议

物源体系分析是沉积盆地特征分析的重要内容,为进一步阐明珠江口盆地恩平凹陷恩平组的沉积特征和物源体系,本文拟利用恩平凹陷的三维地震资料和钻井数据,通过古生物环境分析和锆石U- Pb定年等方法,并借助地震剖面中古沟谷的识别、前积反射结构、地震多属性分析结果和沉积相带平面分布特征,对恩平凹陷恩平组物源体系特征进行综合分析。研究结果表明,恩平组PSQ1～PSQ2时期表现位明显的陆相湖盆特征,物源主要为珠江口盆地内隆起的古生代变质岩和中生代火成岩基底,少量来源于北部华南褶皱带的元古宙变质岩;随着PSQ3时期断层活动逐渐停止,湖平面不断上升,华南褶皱带物源供给能力明显增强,逐渐成为恩平凹陷主要物源。鉴于目前南海北部缺少陆相湖盆地层的完整岩芯剖面,制约了南海北部裂陷期构造- 沉积耦合研究并影响了该地区的油气勘探,建议下一步在南海北部陆相沉积盆地(如珠江口盆地)开展大洋钻探工作,以便获取更连续、时间精度更高,受风化作用影响更小的陆相湖盆地层的完整岩芯剖面。这不仅有利于指导下一步油气勘探,也可通过重建陆相沉积盆地不同地质历史时期的沉积变化过程,为了解古气候状态和预测未来气候变化提供重要依据。     

国外深地震反射研究之现状

本文概括地总结和回顾了深地震反射研究成果,并针对存在的一系列问题进行了讨论。许多国家利用深地震反射法来研究大陆地壳和上地幔的内部结构。研究成果表明,大陆地壳和上地幔的反射特征具有显著的差异,这些差异反映了不同的构造单元和状态。     

庐江-枞阳矿集区深部结构与成矿

为探测长江中下游成矿带庐江-枞阳白垩纪火山岩盆地和铁、硫矿集区深部构造和地壳结构,探讨成矿深部控制条件,作者完成了穿越火山岩盆地的深反射地震剖面(记录30 s)和罗河铁矿区浅层高分辨反射地震剖面,揭示了矿集区全地壳精细结构,同时开展区域构造测量和应力场反演研究,获得了新的认识.证实"耳状"的庐-枞火山岩盆地是一个沿北东向罗河断裂向东发育的非对称火山盆地,排除了另一半被断在两侧红层之下的判断;罗河断裂是一条切穿MOHO的深断裂,倾向南东,是引导地幔流体和岩浆上涌和喷发的通道;鉴别出多层界面,火山岩-侏罗系砂岩厚约4-5 km(其中火山岩厚度约3 km),三叠系-震旦系变形层底界深度大致18-20 km,变质基底组成中下地壳,MOHO平缓向西北倾,深度33-31 km;追踪郯-庐断裂带的深部产状,陡立延伸到MOHO,宽约10 km.     

反射地震在冀中坳陷保定凹陷精细地质结构探测中的应用

保定凹陷位于渤海湾盆地冀中坳陷西缘,其西侧以太行山山前断裂为界与太行山隆起相邻,查明凹陷内深部构造和精细地质结构,对油气勘探和深部热储调查评价有着重要的意义,同时对太行山山前断裂的发育特征的研究也有一定的帮助。反射地震勘探在深部地质结构探测中具有高精度、高分辨率的优势,因此,在保定凹陷构造单元及其外围开展了深反射地震测量,采用炸药震源激发、长排列多道接收、高覆盖次数的工作方法,获得了高品质的原始地震记录。通过静校正、叠前噪声压制、反褶积和偏移叠加等高精度成像数据处理方法技术,得到能清晰反映测区深部地质结构和构造特征的反射地震剖面。地震剖面清楚地查明了凹陷内断裂构造特征,以此划分了内部次级构造单元。根据地震剖面上识别的角度不整合面,划分了基底构造层、断陷期构造层和凹陷期构造层,并据此探讨了3个构造层的构造演化过程。     

雄安新区地热地质模型探究：来自地球物理的证据

雄安新区内地热资源丰富，区内有牛驼镇地热田、容城地热田和高阳地热田，地热资源开发利用较早，但是对其深部热源机制仍未形成统一观点。为了研究雄安新区内地热田深部热源机制，在新区及外围进行了深反射地震和长周期大地电磁探测，对取得的同剖面的深反射地震和大地电磁数据进行处理和综合解释，探明了研究区从地表至莫霍面范围内地质构造和电性结构。下地壳结构在深反射地震剖面与大地电磁剖面上有很好的对应关系。电阻率低值区对应着在深反射地震剖面上存在一系列反射同相轴，且同相轴可以延续到莫霍面，电阻率高值区对应着在深反射地震剖面上无明显连续反射同相轴，尤其是在莫霍面之上呈现地震反射近似"空白区"。结合区域地热资料构建了研究区深部地热地质模型，对新区内深部地热机制进行了解释。该模型为"二元"生热模型，其热源包含两个部分，深部地幔热源和地壳放射性元素衰变生热。放射性元素衰变生热占地表热流的接近30%，而幔源热流在地表热流中的占比可达约70%。在牛驼镇下方，莫霍面以上，由于地幔热物质上涌造成下地壳上隆，幔源岩浆底侵作用于下地壳形成了局部热异常，该热异常具有低速高导的地球物理特征，认为是牛驼镇地热田和容城地热田的深部热源；以区域断裂为热通道，大地热流由深部向上传导、扩散到牛驼镇凸起和容城凸起顶部，对碳酸盐岩储水层进行加热，形成地热储层；上覆新近系沉积地层是良好的热盖层。     

长江中下游成矿带岩石圈结构与成矿动力学模型——深部探测(SinoProbe)综述

岩石圈结构和深部过程对理解成矿带和大型矿集区的形成十分重要。岩石圈尺度的地球动力学过程将在地壳中留下各种结构的或物质的"痕迹",这些"痕迹"可以通过地球物理的手段去探测。为深入理解长江中下游成矿带形成的深部动力学过程,作者在国家深部探测专项(SinoProbe)和国家自然科学基金重点项目支持下,在长江中下游成矿带开展了综合地球物理探测。方法包括宽频地震、深地震反射、广角反射/折射和大地电磁测深。数据处理和反演结果取得一系列新发现:(1)成矿带上地幔顶部存在低速体,在中心深度300km处有一向SW倾斜的高速体;(2)S波接收函数证实成矿带岩石圈较薄,只有50~70km;横波分裂结果显示,成矿带上地幔各向异性方向和强度与邻区有较大区别,显示平行成矿带(NE-SW向)的上地幔变形和流动;(3)深反射地震揭示成矿带上地壳曾发生强烈挤压变形,以紧闭褶皱、逆冲和推覆为特征;在宁芜火山岩盆地、长江断裂带和郯庐断裂之下出现"鳄鱼嘴"构造,指示上下地壳在挤压变形过程中解耦;深反射地震证实发生过陆内俯冲和叠瓦,并认为是岩石圈增厚和拆沉的主导机制;(4)广角反射和大地电磁反演给出了跨成矿带地壳剖面的速度和电性结构,速度和电阻率分布总体上与构造单元相吻合。本文分析和解释了这些发现的地质意义,并结合近年在长江中下游地区的地球化学研究进展,提出了成矿带地球动力学模型。该模型认为:中、晚侏罗世陆内俯冲、岩石圈拆沉、幔源岩浆底侵和MASH过程造就了长江中下游世界级成矿带的形成。     

川黔湘构造带构造样式及深部动力学制约

川黔湘构造带可划分为4个不同的构造带,其中雪峰山构造带地理位置特殊,恰位于华南块体南北向重力梯度带上,两侧岩石圈厚度差异显著,其成因机制历来是争论的焦点。雪峰山构造带基底是一个花状结构,与川黔隔槽式褶皱带构成一个整体,为一个厚皮结构。雪峰山基底在沅麻盆地隆升最高,表现为压扭性构造特点。参考深反射剖面,绘制了研究区浅层与深部结构地质剖面。板块受挤压,中、上地壳与下地壳存在不同的耦合方式,对此分析了研究区下地壳的变形过程。雪峰山下地壳向下存在对冲,形成山根,但并没有俯冲至地幔。随地壳加厚,岩石圈发生弯曲,下地壳与上地幔存在瑞利泰勒不稳定性,并下沉至软流圈地幔。晚中生代,伸展背景下的软流圈上涌使雪峰山以东岩石圈发生拆沉,致使两侧岩石圈厚度出现差异。