【作者】 李洪强；

【导师】 高锐；

【作者基本信息】 中国地质科学院 ， 地球探测与信息技术， 2014， 博士

【摘要】 深地震反射剖面技术已被国际地学界公认为是探测岩石圈精细结构,研究大陆构造变形和深部过程的有效手段。深地震反射剖面技术是在常规地震反射方法的基础上发展起来的,两者原理基本相同,都是利用不同物性界面产生的弹性波反射同相轴来描述界面、断裂等地下构造特征。但是,由于深地震反射剖面与石油地震反射剖面采集方式和观测参数有很大不同,如探测深度大(地壳尺度或岩石圈尺度),深层近似近垂直反射、深井组合大药量激发(几十、几百、上千公斤炸药,有时达几十口井组合激发)、排列长接收(几十公里)等等,使深地震反射剖面数据处理同石油反射地震剖面数据处理存在较大差异。地震数据处理是连接野外数据采集和室内数据解释的纽带,地震数据处理的质量直接决定后续解释的可靠性。本文针对深地震反射剖面数据深层频率低、中下地壳速度分析精度低、深层成像困难等核心问题,分别重点研究了深地震反射剖面面波干扰压制、深地震反射剖面与深地震测深(宽角反射与折射地震)走时联合获取深部速度结构、近垂直深地震反射剖面单次覆盖剖面约束莫霍面构造形态等关键技术,并将以上关键技术研究成果应用于秦岭深地震反射剖面数据处理中,获得了大巴山-南秦岭区域地壳和上地幔构造格架及变形特征。本论文研究取得了以下主要研究成果和认识：1.异常振幅识别的面波衰减技术：在深地震反射剖面中,面波通常以低频特点与下地壳有效信号混存在一起,如何压制面波提取下地壳有效信号,是深地震反射剖面数据处理的一个难题。本文在保护低频信号前提下,根据面波强能量特征,利用信号空间的相似性原理,在频率域将有效信号数据与面波分离。通过异常振幅识别技术在时间-空间域识别、拾取面波振幅和有效信号振幅,将识别的异常振幅通过高斯赛德尔方式进行多域分解,用求解的比例因子在炮域、检波点域对面波实施衰减,将面波的能量衰减到和有效信号同一能量水平,将衰减后的面波数据和有效信号叠加,从而有效的压制了面波干扰；2.同测线深地震反射剖面与深地震测深相互约束共建地壳层速度结构技术：地壳速度是深地震反射剖面数据处理的关键参数,以往处理中往往紧靠反射地震数据的速度分析获取速度模型,用于叠加处理、偏移处理等。由于深地震反射剖面探测深度深达下地壳及岩石圈地幔,反射地震对如此深的地层速度反应不灵敏,难以准确进行速度分析,常常困扰着深地震反射剖面的数据处理。本文利用CVI(约束层速度反演)技术,利用反射地震数据沿层提取浅层速度结构,利用深地震测深数据提取深部速度结构,联合建立全地壳初始速度模型。采用剥层的方式,采用反射层析分析方法自浅到深逐层更新速度模型,并利用射线追踪技术先后模拟自激自收剖面、共反射点道集、共炮点道集,通过多次迭代获得处理剖面地壳层速度结构。运用该层速度进行叠前偏移及叠加剖面时深转换,通过模型数据试验研究取得了较好的效果,并应用到六盘山深地震反射剖面数据处理中；3.近垂直深地震反射剖面大炮单次覆盖剖面确定莫霍面形态的技术：莫霍面是深地震反射剖面探测的重要界面。国际学者近来试验采用大炮技术探测厚地壳的莫霍面。本文根据深地震反射剖面大炮数据近垂直反射特点,以及大炮数据深层反射能量强、频带宽等特征,使用地壳平均速度计算炮点下方莫霍面深度、使用1/4地震波周期,确定莫霍面对应的近垂直反射区范围,建立反映莫霍面构造形态的单次覆盖剖面,进而对深地震反射剖面的后续处理提供约束。将近垂直深地震反射剖面大炮单次覆盖剖面技术运用到六盘山、秦岭深地震反射剖面数据处理中,对莫霍面形态进行成像,取得了较好的效果；4.对秦岭深地震反射剖面南段数据进行数据处理与地震成像。采用了常规处理和一些针对性的关键处理技术,处理剖面成功获得南秦岭地壳构造格架,捕捉到四川盆地岩石圈俯冲到南秦岭之下的证据,确定出地幔缝合的位置,揭示大巴山和南秦岭上地壳逆冲构造变形行为及相互关系,发现在南秦岭上下地壳之间(15-20km左右)存在一个壳内构造滑脱层。更多还原

【Abstract】 The deep seismic reflection technology has been recognized as the effected means to probe lithospheric fine structure, continental base and deep geological issues.The deep seismic reflection technology was developed from the conventional seismic reflection method, and their principles are same. Their principle that the elastic wave reflects lineups when it meets different physical property boundaries is to describe the geological structural features, e.g. interfaces and faults. The seismic data processing is the intermedia that connect the field data observation with the indoor information interpretation and inversion, and its quality directly determined the precise and reliability of the subsequent interpretation and inversion. The differences of the explored target layers and parameter acquisition results in the large differences between the deep seismic reflection data processing and the petroleum reflection seismic data. The frequency of the deep seismic reflection data is low, the aanalytical precision of the middle and lower crust velocity is poor, and the deep imaging is difficult. Considering the above characteristics, in this thesis I carried out a few of studies on the key skills, for example the suppressing the deep seismic surface wave interference, deep reflection, wide angel reflection, jointly acquire the deep velocity structure through refraction travel time, constraining the deep structure by sub-vertical one-time cover section. And I applied these key skills to process the deep seismic reflection data of Qinling and obtained the structural framework and the deformational features of Dabashan-South Qinling crust and upper mantle. The research results and understandings I obtained were listed as follows:1. The surface wave attenuation technology to discriminate anomaly amplitude: under the condition that the low-frequency signals were not damaged, to make the energy of surface wave attenuated to the same level with the valid signal. On the basis of the energy features of the surface wave, preliminarily decomposed data into surface wave and valid signal in frequency domain, then to discriminate and collect the surface wave amplitude and the valid signal amplitude in the T-X domain through ZAP skill. The abnormal amplitude that was discriminated will be discomposed in multi-domain through gauss-seidel. The scale factor of the answer attenuated the surface wave in the shot domain and geophone domain. Finally, the attenuated surface wave data overlaid with valid signal; 2. Building the seismic sounding/deep seismic reflection and measuring line strata velocity technology:using CVI method, I established the initial velocity model through collect the superficial layer velocity structure that were overlaid velocity and the structure of the deep seismic sounding. Adopting delamination, I repeatedly iterated to successively simulate that the every layers velocity structure of self-excitation and self-receive section, common reflected points set, common shot channel set respectively from shallow to deep through the reflecting tomography update rate model and the ray tracing technology. The velocity of this layer was used to offset before the iteration or to conduct time-depth conversion on the stacked sections. Through verifying the model data and deep seismic reflection section of Liupanshan, the results were preferable.3. The one-time cover section technology of the sub-vertical reflection big shot: it is strong that the reflectional energy of the deep seismic reflection big shot and frequency band is wide. The scope of the sub-vertical reflection area was determined by predicting the velocity, dominant frequency, travel time of Moho. According to the sub-vertical reflection area of the big shot, the one-time cover section was established. However, the section must be along the deep seismic reflection measuring line and reflect deep structure. The one-time cover section will provide the quality control to the successively processing on the deep data. The one-time cover section technology of the sub-vertical reflection was applied to the Moho imaging of the deep seismic reflection on Liupanshan and Qinling area, and the preferable results have been achieved.4. For imaging the data of the deep seismic reflection section collected from the Qinling, a few of corresponding processing technologies were adopted. Through processing section, the structural framework of the deep seismic reflectional measuring line of the Qinling was attained. The evidence that the Sichuan Lithosphere subduct under the Qinling Lithosphere was captured. The evidence revealed the correlation between the Daba Mountain and the thrust faults of upper crust of the South Qinling. In addition, it demonstrated an angular unconformity plane between upper and lower crust of the South Qinling.更多还原