复杂山区三维地震勘探野外施工方法

三维地震勘探项目野外复杂的地表情况直接影响地震资料的采集难度和采集质量。通过对河南、内蒙古、新疆、山西等多个省份难度高的复杂山区野外项目现场实际施工经验分析,总结出一些针对复杂山区野外施工的特殊方法,可以有效的降低野外施工成本,提高野外施工效率和质量。     

Geochemistry and tectonic significance of Early Cretaceous granites in Highland 1248 of Daxing'anling

The Early Cretaceous granitic complex in Highland 1248 of Daxing''anling successively consists of in- truded granodiorite,monzonite granite and syenite granite． Through test analysis on the major,trace and rare earth elements of the intrusive complex,this study focuses on the source characteristics and tectonic environ- ment of the original magma of intrusive complex． The results show that the intrusive rocks in Highland 1248 are meta-aluminous-peraluminous rocks in calc-alkaline series with homologous characteristics in δEu negative anomalies; the complex is enriched in LILE (Ｒb,Cs and K) and depleted in HFSE (lanthanide,Sc,Y,U, Nb and Ta),displaying the geochemical characteristics of I-type granites in active continental-margin subduc- tion zones． The complex also has the characteristics of granites after the collision of plate with rich aluminum and high potassium,but significantly depleted Nb,Ta,Ti,P and other elements,i． e． in the orogenic evolu- tionary stage． The zircon U-Pb SHＲIMP isotopic apparent age of the complex in Highland 1248 is 140． 0--141. 0 Ma,and the formation time is in Early Cretaceous．     

Study on virtual source method under complex overburden in horizontal well

In conventional seismic exploration,complex overburden prevents us from imaging the deeper under- ground structure,because near-surface velocity model cannot be efficiently simplified and accurately estab- lished． The virtual source method provides a promising solution,which images below a complex overburden without the knowledge of overburden velocities and near-surface changes． In this paper,the authors simulate the forward modeling under complex overburden with sources on the surface and receivers in the horizontal well, and reset the real sources into the horizontal well using the virtual source method,which subtly avoid the distor- tion effects of the complex overburden． Finally the underground structure can be imaged using Kirchhoff migra- tion,so the feasibility and advantages of the virtual source method are verified．     

基于多方向多源合成孔径雷达数据融合的假彩色正射影像制作

在复杂地形条件下,SAR影像几何失真大,辐射畸变突出,透视收缩、叠掩和阴影等现象严重,制约SAR测图的应用.为此,提出一套基于多方向多源SAR数据融合方法与技术流程,利用不同侧视方向、不同分辨率、多极化的SAR影像数据,融合制作信息量丰富,能够满足应用要求的SAR假彩色正射影像.采用横断山脉区域3 m分辨率的Terra...     

基于二级近似离散复镜像法的低频电磁格林函数计算

本文讨论了利用二级近似离散复镜像法实现低频格林函数快速、精确的计算.通过数值分析,给出了在低频电磁场计算中该方法近似参数的选取原则.(1)二级近似的积分区间里谱格林函数采样个数N为十倍的近似多项式的个数M;(2)总的积分区间L2大小约为40/r,r为收发距离;(3)两个积分区间的分界值L1为总的积分区间大小L2与第二个...     

Extraction of real modes and physical matrices from modal testing

A technique to extract real modes from the identified complex modes is presented in this paper, which enables the normalized real mode shapes, modal masses, and full or reduced mass and stiffness matrices to be obtained. The theoretical derivation of the method is provided in detail. An 11-DOF vibration system is used to validate the algorithm, and to analyze the effects of the number of modes utilized and measurement DOFs on the extraction results. Finally, the method is used to extract real modes from both experimental modal analysis and operational modal analysis.     

Post-collisional magmatism in the northern Arabian-Nubian Shield: The geotectonic evolution of the alkaline suite at Gebel Tarbush area, south Sinai, Egypt

Post-collisional alkaline magmatism (∼610–580 Ma) is widely distributed in the northern part of the Neoproterozoic Arabian-Nubian Shield (ANS), i.e. the northern part of the Egyptian Eastern Desert and Sinai. Alkaline rocks of G. Tarbush constitute the western limb of the Katharina ring complex (∼593 ± 16 Ma) in southern Sinai. This suite commenced with the extrusion of peralkaline volcanics and quartz syenite subvolcanics intruded by syenogranite and alkali feldspar granite. The mineralogy and geochemistry of these rocks indicate an alkaline/peralkaline within-plate affinity. Quartz syenite is relatively enriched in TiO₂, Fe₂O₃, MgO, CaO, Sr, Ba and depleted in SiO₂, Nb, Y, and Rb. The G. Tarbush alkaline suite most likely evolved via fractionation of mainly feldspar and minor mafic phases (hornblende, aegirine) from a common quartz syenite parental magma, which formed via partial melting of middle crustal rocks of ANS juvenile crust. Mantle melts could have provided the heat required for the middle crustal melting. The upper mantle melting was likely promoted by erosional decompression subsequent to lithospheric delamination and crustal uplift during the late-collisional stage of the ANS. Such an explanation could explain the absence or scarce occurrence of mafic and intermediate lithologies in the abundant late- to post-collisional calc-alkaline and alkaline suites in the northern ANS. Moreover, erosion related to crustal uplift during the late-collision stage could account for the lack or infrequent occurrence of older lithologies, i.e. island arc metavolcanics and marginal basin ophiolites, from the northern part of the ANS.     

孟加拉湾缅甸若开盆地上新统斜坡水道复合体沉积特征

斜坡水道复合体是孟加拉湾缅甸海上若开盆地上新统最重要深水沉积结构单元之一。研究工作以地震响应与深水储层之间的对应关系为指导,二、三维地震资料中的强振幅属性用以判断水道复合体内的粗粒沉积。利用多种地震技术,包括相干切片分析、地质异常体处理以及三维可视化,将斜坡水道复合体从背景中区分出来,并从斜坡水道复合体的外部几何形态、...     

青藏高原东南缘点苍山-哀牢山杂岩带中片麻岩的变质演化及深熔作用特征

片麻岩是点苍山-哀牢山变质杂岩带最常见的岩石类型,主要由夕线石榴黑云二长片麻岩、石榴黑云斜长片麻岩以及含十字石蓝晶夕线石榴片麻岩所组成,其原岩的化学成分与华北克拉通典型孔兹岩系十分相似.岩相学、成因矿物学和变质反应性质研究以及温压条件估算结果表明,研究区片麻岩类岩石变质峰期的温压条件为T=700～770℃,P=0.5～0.8GPa,已达到或接近麻粒岩相变质,晚期退变质阶段的温压条件为T=600～650℃,P=0.35～0.45GPa.片麻岩变质演化的P-T轨迹具有顺时针型式.在麻粒岩相变质阶段,片麻岩类岩石普遍发生深熔作用,主要表现为含水矿物黑云母的脱水熔融和长英质矿物的部分熔融.该项研究对于进一步揭示青藏高原东南缘点苍山-哀牢山造山带的变质演化深熔作用机理及动力学过程具有重要的科学意义.     

西藏东南部察隅地区德玛拉岩群的同位素年代学研究及其意义

青藏高原冈底斯地块东南部的德玛拉岩群为一套角闪岩相变质岩系,一直被认为是前寒武纪变质基底,但并没有可靠的年代学证据。论文对采自其中的黑云角闪片岩和黑云母石英片岩进行了锆石LA-ICP-MS U-Pb定年和黑云母³⁹Ar-⁴⁰Ar定年,测试表明,黑云角闪片岩原岩锆石U-Pb年龄为217.1Ma,由黑云母³⁹Ar-⁴⁰Ar获得的变质年龄为22.3Ma,黑云母石英片岩中碎屑锆石主要为岩浆成因,年龄范围主要集中在520~600Ma和900~1100Ma,黑云母³⁹Ar-⁴⁰Ar变质年龄为16.3Ma和22.3Ma。上述结果虽不能完全否定西藏东南部察隅地区前寒武纪基底变质岩系的存在,但至少说明现今的德玛拉岩群中还包含有遭受中生代岩浆侵入的古生代沉积岩,它们在新生代经历了变质和岩浆作用的再造,是一套变质杂岩。