婆罗洲北部岩石密度和磁化率特征及其对南海南部前新生界岩性识别的约束

基于540块样品的体积磁化率-比重测量和矿物-岩性鉴定结果,分析了婆罗洲北部岩石类型、密度、磁化率特征,据此明确重磁资料对于南海南部中生界岩性识别的适用性.结果表明婆罗洲北部发育3类25种岩石,以发育中基性火成岩和外碎屑沉积岩为主,发育少量内源沉积岩、酸性火成岩和变质岩.具有极强磁性-强磁性,高密度-中等密度特征的岩石多为火成岩和凝灰质砂岩及其变质岩.弱磁性-无磁性、中等-极低密度特征的岩石多为砾岩、砂岩、粉砂岩、泥岩和煤等.弱-逆磁性、高-中等密度的岩石多为灰岩和硅质岩.新生界岩石具有密度较低、磁化率中等的特征.中生界岩石具有密度中等、磁化率中高的特征.前中生界岩石具有密度高、磁性低的特征.结合分布特征可知,前中生界岩石产生局部弱重力异常,中生界沉积岩产生区域性的负重力异常,火成岩产生区域性的正重力异常.南海南部的区域性高磁力异常来源于中生代的基性火成岩(及其变质岩),区域性中等磁力异常可能来源于酸性火成岩(及其变质岩).据此进行了南海南部中生界岩性的识别,结果表明南海南部存在大面积的中生界沉积岩分布区,认为南海南部中生界地层具有油气勘探潜力.     

扬马延微陆块中部重力场及构造特征

为了研究扬马延微陆块中部的构造特征,进而为该区油气远景调查评价提供依据,本文基于最新船测重力测量资料计算了自由空气重力异常,并对自由空气重力异常数据利用正则化滤波方法进行了异常的分解,获取了扬马延微陆块中部的局部重力异常以及区域重力异常.结合已有的地质及地球物理研究成果,对自由空气重力异常、局部异常、水平总梯度异常、欧拉反褶积定位解特征进行了深入分析,确定了该区的断裂构造格架,划分了本区构造单元.研究认为:本区重力高异常与重力低异常相间分布的特征反映了该区凹陷与隆起分布的范围及展布特征.研究区主要发育北东向、北西向(北西西向)2组断裂,这2组断裂对基底结构、性质、隆坳格架及中-新生代盆地展布起重要的控制作用.研究区可划分为扬马延盆地、扬马延西翼构造带、扬马延中部凸起带、扬马延海槽以及扬马延南部复杂构造带等5个构造单元,构造单元之间呈断层接触关系.     

南海北部磁异常特征及对前新生代构造的指示

为了研究南海北部前新生代构造,利用新近的船载磁力测量数据,对磁异常进行变纬度化极,并反演计算视磁化强度和磁源重力异常,以及对三条OBS剖面进行重磁拟合.结果认为东沙隆起高磁异常带是浙闽沿海火山岩带向西的延续,其间被NW向古老的转换边界断裂F10错断;NE向的F2断裂是高磁异常带的南界,并限制了底侵活动的北界;F3断裂在...     

江汉盆地构造模式和演化及其与中强地震关系研究

本文通过对江汉盆地地震物探的剖析,结合该地区大地构造环境特点,指出盆地主要有三个发展阶段组成:前陆盆地阶段(中三叠-晚侏罗纪),主要受秦岭大别逆冲推覆,前缘挠曲形成前陆盆地,同期形成NW向和NEE-EW向两组断裂,从而奠定了盆地棋盘格网构造体系;断陷盆地阶段(白垩纪-老第三纪),断裂由原逆冲或逆走滑转变为正断性质,且控制盆地沉积中心,同时盆地发生顺时针旋转,岩浆活动强烈;新第三纪以来盆地阶段,盆地以坳陷为主,整体下降,表现为断裂对盆地沉积控制明显减弱,岩浆活动停止. 根据石油物探剖面建立了盆地的构造格架,即盆地内两组断裂及其形成的狭窄低凸起/地垒条带将盆地分为4个NNW向展布和3个NEE向展布凹陷带. 盆地地壳结构和小震分布及震源机制解显示地震集中在沉降最大的潜江-沔阳凹陷带附近,震源深度优势分布在15 km左右,即盆地基底附近.     

胶莱盆地重磁资料解释与构造特征分析

胶莱盆地位于郯庐断裂带东侧，是典型的拉张盆地，内部划分为诸城凹陷、柴沟地垒、高密凹陷、大野头凸起、莱阳凹陷、牟平──即墨断裂带、海阳凹陷。运用重力资料一级近似解法，定量计算了胶莱盆地基底埋深，结合磁异常解释等，本文重点讨论了盆地内主要断裂的形成时期，切割深度及空间演化。并进一步将诸城凹陷细分为胶县洼陷、集王疃洼陷、平度洼陷、马山构造带、刘家庄构造带、李党家构造带。讨论总结了该盆地构造特征及其发育规律，为该区油气勘探提供了新的认识与依据。     

利用重磁资料研究莺-琼盆地构造分界及其两侧断裂特征

莺-琼盆地(即莺歌海盆地和琼东南盆地)位于印支地块与华南大陆交汇处,该区域地质构造复杂,为南海西北走滑型和伸展型陆缘的交汇区,也是印澳-欧亚板块碰撞“挤出-逃逸构造区”和“古南海俯冲-拖曳构造区”.莺-琼盆地的北部以红河断裂带中1号断裂为界,前人对其认识比较统一,但莺-琼盆地南部由于地质和地球物理资料较少、研究程度低,以致其构造格局及分界位置不明确.通过对重、磁资料的处理,认为在莺-琼盆地分界的北段存在明显的重力异常和磁力异常梯级带,该梯级带与1号断裂位置相对应;在其南段存在明显的重力异常和磁力异常高值带,推断该高值带为一“中建凸起”,结合重、磁对应分析技术确定了该“中建凸起”的分布范围.采用重、磁异常归一化总水平导数垂向导数技术识别出控制莺-琼盆地分界两侧的断裂构造,在分界以西断裂走向主要为北北西向,分界以东主要为北东向.通过地质和地球物理综合研究认为莺-琼盆地的北段以1号断裂为界,南段以“中建凸起”为界.     

基于布格重力异常研究运城盆地的构造特征

利用运城及周边地区的布格重力资料,对布格重力数据进行小波分解得到不同阶次的重力异常信息。依据各个阶次的小波变换结果并结合该区域的地质构造环境,对小波变换细节图中存在的特征较为明显的布格重力异常带进行深入分析,对异常所揭示的构造现象在地壳不同深度的分布特性等进行分析研究。结果表明:小波变换细节与区内地壳内部的隆起、凹陷及断裂构造具有很好的对应关系,可以对运城盆地的构造特征及地壳结构做更加深入的研究。     

东海陆架盆地重震联合解释推断研究

目前,我国海洋区域地质调查以重磁为主,辅以二维地震,用单一的物探方法难以探测海区沉积盆地中的各个密度界面,本文充分发挥地震、重力和磁力资料的特点,进行优势互补,利用重震联合界面反演技术,对东海陆架盆地的三个密度界面,上新统底界面、中新统底界面和沉积基底进行反演,利用反演结果对研究区的构造区划进行重新认识.东海陆架盆地西部凹陷基本缺失渐新统,海礁凸起南北两块的分界处东西方向的长度较短,钱塘凹陷向东北方向延伸较长,东部西湖凹陷地层发育齐全,新生代沉积厚度大,沉降幅度大,底界面在11794米左右.说明利用重震联合密度界面反演及解释是一项可行的技术.     

中国东部及邻近海域磁异常数据所揭示的深部构造

通过对中国东部及邻近海域磁异常数据的化极和上延处理,全面分析了不同构造块体和区域深大断裂的磁异常特征和空间展布,并在此基础上,通过计算化极后的磁异常数据的径向平均振幅谱,反演计算出区域居里等温面的深度分布．研究发现磁异常的化极和上延处理有效地增强了区域构造带（大别造山带、郯庐断裂、钓鱼岛隆起等）的边界特征．计算得到的居里等温面深度在19．6～48．9km之间,平均深约31．7km,下扬子地区的苏北盆地和南黄海盆地的居里等温面明显较深,最深可达35km左右,而其周围区域的居里等温面深约25km,表明了下扬子地区的苏北盆地和南黄海盆地在构造演化以及基底岩性和结构上的独特性．从区域上看,沉积盆地（苏北盆地、南黄海盆地、东海陆架盆地）的居里等温面一般较深,而周围隆起区（钓鱼岛隆起、浙闽隆起）的居里等温面一般较浅．在火山活动区（琉球岛弧、济州岛周围）以及沿江绍断裂海域部分居里等温面隆升非常明显,表明来自深部强烈的岩浆或其他地热活动．     

渤海残留盆地分布综合地球物理研究

以活动论构造历史观为指导进行渤海海域残留盆地宏观分布特征研究. 以岩石物性为基础建立地质界面与物性界面的联系，通过重、磁、震等方法组合圈画不同物性界面的分布特征. 浅层沉积盆地结构通过反射地震资料控制，深层地质结构信息利用重磁异常场分离、物性界面反演等方法得到. 在地层分布格架基础上分析前新生代残留盆地宏观分布范围. 并结合渤海海域实例研究介绍了残留盆地宏观分布研究的技术方法和流程，在计算上古生界-中生界及元古界-下古生界残余地层厚度的基础上给出了渤海海域残留盆地的宏观分布范围，并指出在歧口凹陷东南部、石臼坨隆起南部及东北部、渤南凸起南部、辽东湾等地区是较好的前新生代油气潜力区.     

New magnetic data of the southern East China Sea and some geological interpretations

In September and October of 2011, a marine magnetic survey was conducted in the southern East China Sea between 120° and 126°E, 26° and 28°N with the research vessel Kexue-3. New magnetic maps with 5 × 5 km grid spacing were generated after meticulous data processing. Based on an analysis of magnetic anomaly features and further calculation results, including the total horizontal derivatives (THD), second order vertical derivatives (SVD) and analytic signal amplitude (ASA), several new tectonic insights on magnetic sources, basement structures and fault properties were obtained. The NE-SW or NNE-SSW oriented magnetic anomaly highs have different sources: (1) The high amplitude, short wavelength magnetic anomalies of the Zhemin Uplift are caused by shallow buried igneous rocks intruded along NE-NEE oriented faults. (2) The high amplitude, moderate wavelength magnetic anomalies of the Diaoyudao Uplift are caused by the metamorphic basement intruded by magmatic rocks. (3) The magnetic sources of the Yandang Uplift and Taibei Uplift in the shelf basin are shallow buried metamorphic basements and deep buried volcanic bodies, respectively. Several NW-SE or NWW-SEE oriented dextral strike-slip fault belts were identified as important tectonic boundaries. Each is composed of several en echelon and partly overlapping secondary faults. Initially formed in the Cretaceous, these fault belts have evolved through multiple periods, propagated seaward with the migration of the basement rifting and accommodated local stress fields in the Cenozoic.     

3-D gravity and magnetic interpretation for the Haifa Bay area (Israel)

Recently observed features in the subsurface geology of the Haifa Bay area (northern Israel) have been evaluated using 3-D forward gravity and magnetic modeling and inversion schemes. The interpretation is based on updated petrophysical data of the Jurassic, Cretaceous and Tertiary sedimentary layers and volcanics. It has been shown that the Bouguer gravity anomalies correspond mainly to thickness variations in the Senonian to Tertiary sediments. The gravity effect of these sediments was calculated using their actual densities and structural setting as interpreted from seismic reflection data. This effect was removed from the Bouguer gravity in order to study the pre-Senonian geological structures. The pattern of residual gravity anomalies (named “stripped gravity”) is essentially different from the pattern of the Bouguer gravity. The prominent Carmel gravity high, clearly seen on the Bouguer gravity map, completely vanishes on the “stripped” gravity map. That suggests that this relatively positive anomaly is caused by the considerable thickness of the low-density young sediments in the surrounding areas and does not correspond to high-density magmatic rocks or crystalline basement uplift as previously suggested. The average densities of the Jurassic and Cretaceous volcanics are generally lower then those of the background sedimentary rocks. Volcanics are the main cause for magnetic anomalies onshore and offshore northern Israel. The magmatic root of the Asher volcanics is, most probably, located close to the Yagur fault. A large, deep-seated gabbroic intrusion is assumed to be located under the Mediterranean abyssal plain in the NW part of the study area. The Atlit marine gravity low appears to be caused by a thick Mesozoic and Tertiary sedimentary accumulation. The results presented should be of considerable assistance in delineating some aspects of hydrocarbon exploration in the area.     

合肥盆地和郯庐断裂带南段深部地球物理特征研究

根据重、磁、电、震资料联合反演和综合解释，研究了合肥盆地和郯庐断裂带南段深部结构特征和构造样式. 合肥盆地呈现深部印支面以下为逆冲断层、以上为张性正断层的构造样式，盆地构造反转发生在晚侏罗世，早白垩世是裂陷盆地形成的主要时期，早白垩世晚期合肥盆地发生构造反转，发育冲逆、冲推覆构造. 郯庐断裂带南段表现为“上正下逆”的构造变形样式和正花状构造特征，并经历了复杂的挤压走滑-引张正断层变形过程.     

中扬子江汉平原簰洲湾地区中、新生代构造-热演化史

本文综合运用磷灰石-锆石裂变径迹和（U-Th）/He、镜质体反射率及盆地模拟等手段,深入细致地探讨了中扬子江汉平原簰洲湾地区中、新生代构造-热史演化过程.研究结果表明,研究区中-新生代大规模构造抬升剥蚀、地层冷却事件始于早白垩世（140-130 Ma）;大规模抬升冷却过程主要发生在早白垩世中后期至晚白垩世.研究区虽然可能存在一定厚度的晚白垩世-古近纪地层沉积,总体沉积规模相对较小.综合分析认为,区内应该存在较大厚度的中侏罗统或/和上侏罗统乃至早白垩世地层的沉积;而现今残存中生代中、上侏罗统地层相对较薄,主要是由于后期持续构造抬升剥蚀造成的,估计总剥蚀厚度约4300 m左右.区内中生代地层在早白垩世达到最大古地温,而不是在古近纪沉积末期;上三叠统地层最大古地温在170~190℃之间.热史分析结果表明,区内古生代古热流相对稳定,平均热流在53.64 mW·m^-2;早侏罗世末期古热流开始降低,在早白垩世初期古热流约为48.38 mW·m^-2.     

南海北部陆架西区盆地地质、地球物理场特征及其深部结构

分析了南海北部陆架西区盆地的地质、地球物理场特征，计算了研究海域重、磁资料的1阶小波细节、4阶小波逼近变换。根据分析与计算可知，研究区的布格重力异常以北西低的负值，东南高的正值为特征。在东部及东南部异常等值线走向为北东；西部异常等值线以北西走向为特征；西北地区异常以北东东、北东走向的局部等值线圈闭为特征。磁场的展布十分复杂，按磁异常的变化程度可分为三个变化区，即磁异常平静区、剧变区及缓变区。磁异常的平静区位于研究区的西部，即莺歌海盆地所在位置，这一带磁异常等值线极为稀疏，异常值为负背景异常。剧变区位于海南岛，该地区的磁异常变化极为剧烈，异常特征以局部小圈闭为特征，等值线分布密集。磁异常的平缓区位于平静区及剧变区之外的其它地区。琼东南盆地、北部湾盆地的磁异常具有此特征。根据重、磁场资料以及南海北部盆地钻井取样的测试结果、同时参考穿越南海地学断面的结果，对研究区的地壳结构进行了反演计算，计算表明南海陆架盆地区域地壳结构较为复杂，研究区的地壳厚度在22－33km之间，总的趋势由陆向洋地壳厚度逐渐减薄，反映出该区域地壳具有陆壳、拉伸陆壳、过渡壳的性质，同时存在有上地幔隆起区及凹陷区。磁性底界面厚度在17－24km之间变化，其中在莺歌海盆地较深，在海南岛地区磁性界面较浅。     

大兴安岭西坡德尔布干断裂地球物理特征与构造属性

对1:250万重力异常向上延拓不同高度并分别计算135°方向水平导数,德尔布干断裂表现为北东向延伸的重力场分界线,采用基于DCT法欧拉反褶积对1:10万高精度重磁数据向上延拓0～20 km追踪断裂轨迹,并进行1:100万大地电磁测深反演和海拉尔盆地地震剖面解释,识别出德尔布干断裂具有向南东倾斜,切割深度至下地壳的特征....     

京津唐及邻区地壳结构的中新生代构造运动响应

以华北地块作为实施“国际地壳与上地幔模型计划（IGCP-474）”示范区,我们综合京津唐及邻区的8条宽角反射地震剖面地壳速度结构, 计算了该区域不同构造域上、中及下地壳平均速度和厚度.利用格里金插值技术构建上、中、下地壳平均速度、厚度和底界深度在空间上变化图像.这些图像指示出,京津唐及邻区发育沿近东西和北东两个方向展布的隆起与拗陷,发育受北东向断裂控制的断隆和断坳.这些地质构造的形成与该区域发生在中生代以来的构造运动密切相关,推断京津唐及邻区在中新生代至少发生三期较强烈的构造运动.结合区域构造研究成果得出,近东西向展布的隆起和拗陷形成于三叠纪,北东向展布的隆起和拗陷形成于侏罗纪,受北东向断裂控制的断隆和断坳则形成于白垩纪以来.由于中地壳为壳内低速层,与上、下地壳的变形规律截然不同,以塑性变形为主,造成中地壳在隆起部位厚度大、速度低,拗陷部位厚度小、速度高,其厚度较大的部位地壳强度整体降低,在后期构造运动中易发生断裂变形,进而控制京津唐及邻区现今地震活动.     

Geostatistical Interplay Between Geophysical and Geochemical Data: Mapping Litho-Structural Assemblages of Mesozoic Igneous Activities in the Parnaíba Basin (NE Brazil)

Two widespread magmatic events are recorded in the Parnaíba basin (NE Brazil) during the Jurassic/Cretaceous opening of the Central and South Atlantic Oceans. The Early Jurassic (~ 200 Ma) lava flows of the Mosquito Formation occur essentially in the western and southern basin segments, representing one of the largest expressions of the Central Atlantic Magmatic Province in the South American Plate. In contrast, sill complexes and dike swarms of the Early Cretaceous (129–124 Ma) Sardinha Formation occur in the eastern part of the basin and are chrono-correlated to the large Paraná–Etendeka igneous province and to the Rio Ceará–Mirim Dike Swarm. We gathered geophysical, well logging, outcrop analogs and geochemical data to recognize geometrical shapes and areal distribution patterns of igneous-related constructions. Seismic and well data reveal hundreds of km wide multilayered sill complexes and dikes, which are widespread across vast regions of the basin without evident structural control from either the Precambrian basement grain or the basin internal architecture. Anomaly enhancement techniques and self-organizing maps (SOM) procedure were applied on airborne magnetic data, unraveling near-surface magmatic features in four distinct magnetic domains. Using SOM analysis, the basaltic rocks were divided into six groups based on magnetic susceptibility and major elements composition. These results suggest common origin for both magmatic episodes, probably a combination of effects of edge-driven convection and large-scale mantle warming under the westward moving West Gondwana during the Central and South Atlantic opening, which caused a shifted emplacement to the east of the igneous rocks in the Parnaíba basin.     

Gravity and magnetic field characteristics and hydrocarbon prospects of the Tobago Basin

The Tobago Basin, which is located offshore northern Venezuela with a southern margin close to Trinidad and Tobago, has an area of approximately 59,600 km². The Tobago Basin has relatively favourable hydrocarbon prospects, and to date, exploration work has mainly concentrated on small areas of the southwestern portion of the basin. To conduct a comprehensive study of the structural framework of the basin and the characteristics of the basement in order to identify prospective zones for hydrocarbon exploration, shipborne‐measured and satellite‐measured gravity data, shipborne‐measured magnetic data, and aeromagnetic survey data were analysed. A regularisation filtering method was used to separate and obtain regional and residual gravity and magnetic anomalies. Directional gradients of gravity and magnetic anomalies and the total horizontal gradient and vertical second derivative of gravity anomalies were employed to extract information about fault structures. Regression analysis methods were used to determine the basement depth. The geological significance of the gravity and magnetic fields was examined, the structural framework of the basin was assessed, the basement depth was estimated, and favourable hydrocarbon exploration prospects within the basin were identified. The results show that the Tobago Basin contains complex structures consisting mainly of two groups of faults trending in northeasterly and northwesterly directions and that the major northeasterly trending faults control the main structural configuration and depositional system within the basin. The basement of the Tobago Basin has deep rises and falls. It can be divided into the following four secondary tectonic units: the western sub‐basin, the central uplift area, the southern sub‐basin, and the northeastern sub‐basin. The central uplift area and northeastern sub‐basin are most likely to have developed hydrocarbon accumulations and should be targeted for further exploration.     

琼东南盆地基底特征及其构造演化

本文通过处理琼东南盆地现有的重磁数据资料,得到琼东南盆地重磁特征,并采用三维Parker法进行重磁基底深度的反演,获得琼东南盆地的重力基底深度变化在1～11 km之间,磁力基底深度变化在5～11 km之间,结合地震剖面的重磁震联合反演结果和钻井资料推断琼东南盆地的基底岩性主要以酸性花岗岩和中性安山岩为主,少量陆相中生界地层.琼东南盆地的基底演化表现为早期主要与古特提斯洋的演化相关,晚期则与太平洋板块的俯冲密切相关.