基于统计动力反演的东亚亚热带季风变化驱动机制研究

利用观测数据,运用非线性统计-动力学方法,反演系统各因子之间的相互关系,建立了东亚亚热带季风变化的动力方程,为研究东亚亚热带季风的驱动机制提供了量化参考。研究发现：过去2 000 a东亚亚热带季风是多因子通过反馈机制相互作用影响且具有耦合效应的复杂非线性动力系统,其驱动力主要来源于普若岗日冰芯δ¹⁸О代表的青藏高原热力作用强迫、太阳黑子活动、ENSO、温室气体单因子CO₂和CH₄浓度、北极温度和CH₄及北极温度与7月太阳辐射的耦合作用机制;反馈调节作用主要源于7月太阳辐射与太阳黑子活动、CH₄浓度、中国陆地地表温、CH₄与7月太阳辐射以及CO₂和CH₄的耦合调节作用。并通过动力反演机制推论热带西太平洋对亚热带季风有一定驱动作用,但并不是主要驱动力,即驱动亚热带季风变化的主源地并不在热带西太平洋海区,石笋δ¹⁸О指代的也主要是夏季风信息。     

非饱和土中镉离子传输模型参数反演

使用自行设计的的真空实验装置,采用一维实验室土柱实验方法在不同实验条件下进行了15组实验,并基于实验所得的穿透曲线,使用梯度正则化方法反演得到了镉离子在8种葡萄牙土样和1种比利时土样中相应的传输模型参数。同时通过数值模拟实验验证了梯度正则化方法的有效性和可靠性,进而证明所得结果是有效的。     

巴西构造应力场的遗传有限单元法反演

基于观测的主应力方位资料,应用遗传有限单元法对巴西及邻区边界位移和板内力源进行了反演,确认了前人的研究结果：板块边界作用是控制区域应力场的主要因素,山脉和海岸地形造成的扩展力是控制应力场的一个重要因素．同时显示了板块在垂直载荷下的弯曲对局部水平应力场造成相当的影响．反演结果也表明,除了过去公认的东西向挤压作用外,巴西还受到相当明显的南北向构造作用．它的存在与最近ＧＰＳ资料的分析是一致的．研究还表明遗传有限单元法是偏微分方程反演问题求解的一种有效方法．     

频谱激电法在安徽沙溪斑岩铜矿中的应用

为探查安徽沙溪斑岩型铜矿区深部矿体及隐伏矿体,同时为了试验频谱激电法在此类矿产探测中的应用效果,在安徽沙溪斑岩铜矿区布置了一条2 km的频谱激电法(SIP)测线,经过一系列的数据处理及反演,得到7个不同电性参数断面图,对比分析并结合钻孔地质剖面,视电阻率和相位断面图较好的反映了矿体的形态,极化率和金属因子断面图较好的反映了矿体,电性异常与实际矿体的位置及埋深有较好的一致性.试验结果表明,频谱激电法在斑岩铜矿探测中可以取得较好的效果,该方法在高电阻率、高极化率的金属矿的探测中同样可以发挥重要的作用.     

利用卫星重力数据研究中国及邻域地壳厚度

本文以中国大陆及邻域地壳厚度为研究对象,采用GRACE提供的GX-OG-2-GCM模型数据计算自由空气重力异常,通过确定地核与地幔的质量,分离出由地壳部分产生的重力异常并经过布格改正得到布格重力异常,利用Park公式求出了中国大陆地壳厚度的分布,结果与以前地壳厚度资料相符合.     

横波各向异性在裂缝和应力分析中的应用

针对裂缝性和低孔低渗地层的横波各向异性特征,反演得到横波各向异性参数,研究了裂缝的发育程度、方位和有效性,并对低孔低渗地层的应力场分布状态和方位进行了综合评价;通过对反演得到的快、慢弯曲波形进行频散分析以及计算单极横波各向异性大小,确定了引起横波各向异性的原因,并结合常规测井资料、岩心及FMI成像资料对分析结果进行了验证和对比,最后对研究区8口典型井的横波各向异性进行了综合处理和评价,得到了该区的横波各向异性特征以及和总的应力场走向.结果表明,利用横波的各向异性参数可以有效的评价裂缝的发育程度、走向及有效性,并能准确的确定地应力分布状态和最大水平应力方位.     

Investigation of a Tertiary maar structure using three-dimensional resistivity imaging

This paper presents the application of the electrical resistivity tomography (ERT) method to the investigation of the Tertiary maar structure of Baruth (Germany) known from previous gravimetric surveys. ERT was applied to support the optimum location for a palaeoclimatological drill hole.
  Special modifications of data acquisition, signal processing and inversion are introduced to adapt the method of ERT to the special requirements for the 3-D investigation of structures with horizontal extensions of 1  km or more. More than 5000 dipole–dipole combinations were recorded at three concentric circular electrode arrangements using stand-alone transient data acquisition systems (RefTek).
  We present a fast approximate imaging technique based on the simultaneous iterative reconstruction technique (SIRT). As the complete calculation of the inverse Frechét matrix is avoided, the algorithm is especially suitable for large data and model spaces, where complete inversion is beyond the limits of available computing hardware. The single-step method is applicable to arbitrary irregular electrode layouts. Synthetic tests show that the imaging procedure reconstructs the main features of the subsurface.
  A low-resistivity body could be interpreted as limnic sediments filling the interior of the Tertiary maar crater. Considering the horizontal resistivity gradient, estimates for the lateral and depth extents of the structure were made. An optimum position for a palaeoclimatological borehole was found, and was in good agreement with the gravimetric minimum.     

Tectonic inversion assessed by integration of geological and geophysical data: The intracontinental Rio do Peixe Basin,NE Brazil

Common basin models assume that the post‐rift tectonic evolution of most basins is usually associated with tectonic quiescence. However, tectonic inversion during the post‐rift phase has been proposed for several sedimentary basins worldwide, but how and why it happens is still a matter of debate, especially in intracontinental settings where the lithosphere is old and thick. Here, we use geological and geophysical data from the Rio do Peixe Basin in NE Brazil to show evidence that intracontinental sedimentary basins can be tectonically inverted by far‐field compressive stresses acting on pre‐existing weakness zones of lithospheric‐scale where stresses can concentrate and inversion can occur. Geomorphological and field data combined with seismic reflection, gravimetric and borehole data show that: (a) inversion occurred along two main Precambrian lithospheric‐scale shear zones, the Patos (E‐W trending) and Portalegre (NE‐SW trending), which had already been reactivated as basin‐bounding faults during the earlier rift stage; (b) post‐rift reactivation affected (mostly) the original master normal faults with the largest rift displacements, and locally produced new reverse faults; (c) during contraction, deformation was partitioned between fault reactivation and buckling of the incompetent sediment pushed against the hard basement; (d) all these signs of inversion have been observed in the field and can be demonstrated on seismic reflection profiles; and (e) combined gravimetric and seismic data show that the main structures of the basin were followed by an inversion. These data are consistent with the operation of WSW‐ENE horizontal maximum compressive stress as a result of combined pushes of the Mid‐Atlantic Ridge (towards the W) and the Andes (towards the E), responsible for the post‐rift oblique inversion of normal faults inherited from the rift phase and formed with vertical maximum compressive stress.     

Simultaneous iterative time-domain sparse deconvolution to teleseismic receiver functions

In this paper, we present a new approach to estimate high-resolution teleseismic receiver functions using a simultaneous iterative time-domain sparse deconvolution. This technique improves the deconvolution by using reweighting strategies based on a Cauchy criterion. The resulting sparse receiver functions enhance the primary converted phases and its multiples. To test its functionality and reliability, we applied this approach to synthetic experiments and to seismic data recorded at station ABU, in Japan. Our results show Ps conversions at approximately 4.0 s after the primary P onset, which are consistent with other seismological studies in this area. We demonstrate that the sparse deconvolution is a simple, efficient technique in computing receiver functions with significantly greater resolution than conventional approaches.