利用空间大地测量技术研究地球动力学最新进展

空间大地测量以高精度，高时空分辨率测定地球整体（地球自转）和各圈层（特别是大气，海洋与地壳）的运动，使地球动态变化的监测，研究及应用呈现了崭新的面貌，本文介绍了近年来国际地球动力学最新发展概况，内容包括地壳运动，地球自转，重力场时间变化等。     

When and how did plate tectonics begin？ Theoretical and empirical considerations

Plate tectonics is the horizontal motion of Earth’s thermal boundary layer (lithosphere) over the convecting mantle (asthenosphere) and is mostly driven by lithosphere sinking in subduction zones. Plate tectonics is an outstanding example of a self organizing, far from equilibrium complex system (SOFFECS), driven by the negative buoyancy of the thermal boundary layer and controlled by dissipation in the bending lithosphere and viscous mantle. Plate tectonics is an unusual way for a silicate planet to lose heat, as it exists on only one of the large five silicate bodies in the inner solar system. It is not known when this mode of tectonic activity and heat loss began on Earth. All silicate planets probably experienced a short-lived magma ocean stage. After this solidified, stagnant lid behavior is the common mode of planetary heat loss, with interior heat being lost by delamination and “hot spot” volcanism and shallow intrusions. Decompression melting in the hotter early Earth generated a different lithosphere than today, with thicker oceanic crust and thinner mantle lithosphere; such lithosphere would take much longer than at present to become negatively buoyant, suggesting that plate tectonics on the early Earth occurred sporadically if at all. Plate tectonics became sustainable (the modern style) when Earth cooled sufficiently that decompression melting beneath spreading ridges made thin oceanic crust, allowing oceanic lithosphere to become negatively buoyant after a few tens of millions of years. Ultimately the question of when plate tectonics began must be answered by informa- tion retrieved from the geologic record. Criteria for the operation of plate tectonics includes ophiolites, blueschist and ultra-high pressure metamorphic belts, eclogites, passive margins, transform faults, paleomagnetic demonstration of different motions of different cratons, and the presence of diagnostic geochemical and isotopic indicators in igneous rocks. This record must be interpreted individually; I interpret the record to indicate a progression of tectonic styles from active Archean tectonics and magmatism to something similar to plate tectonics at ~1.9 Ga to sustained, modern style plate tectonics with deep subduction——and powerful slab pull——beginning in Neoproterozoic time.     

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）.     

五台山晚太古代花岗岩的成因及其动力学意义

五台山晚太古代花岗岩（～2.540 Ga）,主要由花岗闪长岩、二长花岗岩、少量的英云闪长岩、奥长花岗岩组成,全岩化学分析表明它们具有中～高钾钙碱性花岗质岩浆性质,LILE富集和高的 w(Rb)/w(Sr) (即: Rb/Sr)比值,相对较低的 w(Sr)/w(Y)、w(La)_n/w(Yb)_n、w(Nb)/w(Ta) 和 w(Zr)/w(Hf) 比值,右斜式稀土配分模式,Nb、Ta、Ti亏损,但是它们均表现了Nd T_DM＝2.54～2.72 Ga和明显的正ε_Nd(t)值。这些地球化学特征表明其钙碱性花岗质岩浆形成于晚太古代大洋岛弧环境,来源于弧下玄武质初生地壳的部分熔融,并经历了一定程度的结晶分异。由于晚太古代洋壳向大洋岛弧俯冲、脱水,引起上覆地幔楔的部分熔融形成弧下初生地壳玄武质物质,这些弧下玄武质物质在少于37km环境下部分熔融形成五台山晚太古代钙碱性花岗质岩浆。     

板块构造正反说

本世纪60年代板块构造概念的出现标志着地球科学革命性的进步．30年来，板块构造学说得到了很大发展，但仍存在一些问题和缺陷，它在海洋和大陆上遇到了许多问题一在研究地球演化的过程中，又在古地磁学与古气候学上遇到了不解之谜，随着研究的深入和技术的发展，有可能建立新的全球理论来取代板块构造．     

广东三水盆地华涌组火山岩分布特征及地球动力学意义

以区域钻井资料、野外露头勘查、岩石样品地球化学分析为依据,结合近年来三水盆地火成岩研究成果,细致刻画盆地内华涌组火山岩的岩性、时空分布以及喷发特征.华涌组火山岩以流纹岩、粗面岩与玄武岩互层为主,呈典型双峰式组合.根据岩性变化特征在华涌组沉积期内识别出四个火山喷发亚旋回,各旋回均由酸性流纹岩或粗面岩喷发开始,以基性玄武岩喷发结束.其中第一、二亚旋回以中心式喷发为主;第三、四亚旋回以裂隙溢流喷发方式为主,火山活动逐渐由强减弱.通过与周边地区区火山岩分布特征的对比研究,可以确定三水盆地华涌组火山岩是在拉张背景下发育的大陆裂谷型火山岩,是南海开裂初期的重要物质记录.     

王庄煤矿放顶煤开采的地质力学分析

由于缺乏对本矿地质力学规律的研究,“三下”采煤及征迁赔偿等工作受到很大制约。因此掌握本矿区综采放顶煤开采条件下的地表移动和变形规律,具有重要研究价值。通过对王庄煤矿4326工作面地表移动观测站观测数据的地质力学分析,得出王庄煤矿放顶煤条件下的地表移动规律,取得了放顶煤开采的地表移动计算参数,为本区域“三下”采煤优化设计提供理论依据。     

沉积盆地动力学与油气

首先简要介绍了沉积盆地动力学产生的背景及研究内容 ;然后重点论述了沉积盆地动力学对成盆、生烃、油气富集的影响及造山带与盆地间的耦合关系 ;最后介绍国际地学界沉积盆地研究动向 ,已由传统的构造沉积分析 ,逐步转向沉积盆地动力学研究     

行星地球动力学与探寻资源和灾害预测

行星地球动力学是研究行星的形成及其深化机制的科学。根据不同圈层间角动量交换的关系和作用机制，我们定性研究了最初地球极在大陆的形成，以及它们的分裂和向外核流体赤道辐合带的漂移。