Structural Origin of Sinjar Anticline, NW Iraq

The Sinjar anticline is a double plunging, trending almost E-W in the northwestern part of Iraq. It extends in Syria for about 42 km, whereas in Iraq, its length is about 91 km, and the width is about 31 km. The northern limb (45° - 80°) is steeper than the southern limb (15° - 25°), with average plunges dip of 35° and axial plane dipping of 47.5° southwards. The exposed rocks in the anticline range in age from Upper Cretaceous, represented by the Shiranish Formation, to Upper Miocene, represented by the Injana Formation. Google Earth image was used to calculate structural data, which were used to indicate the structural origin of the Sinjar anticline. This was achieved by calculating the Aspect Ratio (AR), Fold Symmetry Index (IFS or IFS), and length of the mountain front (FS). Accordingly, it was found that the structural origin of the Sinjar anticline is a fault-bend fold.

准噶尔盆地齐古背斜深浅层泥岩裂缝发育差异性及其制约下油气保存条件

前陆冲断带油气资源丰富,但复杂构造作用下盖层封闭能力的差异阻碍油气勘探进程。目的针对准噶尔盆地南缘冲断带地表油气泄露严重且勘探不足的问题,方法以齐古背斜深浅泥岩盖层为研究对象,在明确地层模型的基础上,结合测井资料反演与实测数据,构建研究区力学参数数值模型,运用有限元方法对齐古背斜古、今构造应力场进行模拟,并将获取的应力场数据与裂缝参数理论相结合,分析盖层的裂缝形成时期,计算现今应力场对盖层裂缝的改造结果。结果结果表明:齐古背斜古、今应力分布受控于埋深、构造位置、断裂走向和断裂汇聚位置;现今应力场下,齐古背斜浅部盖层不易破裂,只对古构造应力场形成的裂缝起改造作用;深浅盖层裂缝发育程度差异大,背斜高点裂缝发育可能是造成浅部油气泄漏的主要原因;裂缝带在断层附近更发育,断层带附近裂缝渗透率远大于正常地层的,可能为深部油气向浅层运移甚至散失提供通道;深部盖层相对稳定,盖层条件不是制约准南下组合勘探成败的关键因素。结论研究结果可为准噶尔盆地南缘冲断带深部油气勘探提供一定参考。

大凉山背斜核部区隧道初支大变形机理与控制

针对大凉山2号公路隧道穿越高地应力背斜核心区域,隧道易发生初支大变形、坍塌、钢架扭曲等问题,通过现场监控量测、围岩岩性实验、理论分析、数值模拟分析和围岩接触压力监测等综合分析,研究了大凉山2号隧道背斜核部大变形成因机理。研究表明:背斜核部玄武岩单轴抗压强度为23.31 MPa,凝灰质泥岩遇水具有一定膨胀性,给围岩变形创造了条件。由于岩层岩性不同,开挖后洞周玄武岩呈独立受弯剪梁状态。相对无水条件下,受地下水补给影响,围岩塑性区面积增加,拱腰部位较为明显。加固前,拱顶沉降量最大达470 mm,拱腰最大收敛值为844 mm,围岩接触压力为523.47 kPa。采用双层小导管+中台阶临时支撑+边墙临时支撑的“主动适应+强支撑”的综合处置方式,隧道拱顶变形减少87.6%,水平收敛变形减少95%,围岩接触压力最大值降至128 kPa,隧道变形得到有效控制。

油气地质勘探将从烃源岩时代进入幔源油气新时代

简要梳理了人类石油勘探发展历程,分析并研究了国内外25个油田(或盆地、油区)的勘探资料,得出结论:石油地质勘探经历过的第一个阶段是背斜(构造)勘探阶段(19世纪60年代~20世纪60年代),第二个阶段是烃源岩勘探阶段(20世纪30年代至今),现在已经进入一个全新的阶段——幔源油气勘探时代。依据幔源油气理论,提出了创新的“盆-壳-幔镜像叠置成藏模式”。

铁峰山背斜构造控滑机制及斜坡破坏模式

地质构造对于区域地质灾害的形成和分布具有控制性作用,从地质构造出发探究地质灾害空间规律是开展灾害易发性评价的关键。以万州铁峰山背斜为例,在地质构造和滑坡灾害实测的基础上,将背斜构造分为核部(Ⅰ区)、北西翼(Ⅱ区)、南东翼陡立岩层(Ⅲ区)、岩层倾斜过渡段(Ⅳ区)和万州向斜(Ⅴ区)5个区,分析了各区内背斜构造控制下的岩体结构及其控滑机制和斜坡破坏模式。结果表明:(1)Ⅱ区岩层由临近Ⅰ区的陡倾角快速变化为临近河谷区的中缓倾角顺向坡,主要控滑结构为顺层发育的泥质、炭质软弱层,顺层岩质滑坡发育普遍;(2)Ⅰ区次级褶皱和断层发育,层面、断层和节理面的组合控制着平面或楔形体滑动,滑动方向常指向褶皱枢纽方向;(3)Ⅲ区主要结构面构成岩块与母岩的分割面,存在顺坡向次要结构面或地形起伏时,发生滑移或坠落式落石,并发展上部岩块的连锁滑坠;(4)Ⅳ区天然顺向斜坡坡度小于或等于岩层倾角,当公路开挖时极易引发顺层面或软弱夹层的顺层岩质滑坡;(5)Ⅴ区为近水平产出的砂泥岩互层,泥岩软化和风化、砂岩裂隙或拉槽充水是控制近水平地层岩质滑坡和落石倾倒、坠落的主要原因。滑坡受铁峰山背斜宏观构造和局部构造的双重控制,前者影响着滑坡的分布和破坏模式,后者主宰着控滑结构和滑坡易发程度。研究成果对于川东褶皱带滑坡灾害调查和风险防控具有指导意义。

江汉盆地江陵凹陷复兴场背斜盐构造特征与成因

复兴场盐背斜是江汉盆地江陵凹陷重要的含油构造,其构造演化及成因机制认识不清,制约了精细勘探。因此,对复兴场盐背斜构造演化及形成机制的分析,不仅有助于理解盐层在不同应力背景下的流动对背斜形成演化的影响,对理解油气成藏过程也有重要意义。通过对三维地震资料的精细解析,结合关键构造层的平衡恢复技术及生长地层分析技术,研究复兴场背斜的构造特征及成因机制。结果显示,复兴场背斜为一构造特征走向上变化显著,受多期次断层改造、多种变形机制复合而成的盐背斜;背斜初始于早始新世新沟咀组沉积期—晚始新世早期的正断层作用,形成滚筒状褶皱并造成盐层的聚集;在晚始新世晚期—渐新世,沉积地层的差异负载作用驱使盐层自西向东流动,造成构造整体西倾,形成单斜构造,并在渐新世晚期抬升剥蚀;背斜定型于新近纪—第四纪,发生构造反转,演化为一挤压型盐背斜,伴生逆断层和膝折构造。复兴场背斜的形成和演化受区域应力背景、沙市组盐层、东倾正断层及盐下古构造等因素的综合作用。复兴场盐背斜形成的构造圈闭略早于烃源岩的主要排油期,并且在主要排油期,构造处于拗陷阶段,断层活动弱,有利于早期圈闭油气的成藏。

柴达木盆地七个泉背斜狮子沟组与七个泉组构造-沉积演化及对砂岩型铀矿成矿的启示

从构造-沉积演化角度分析矿体的形成和发育过程是砂岩型铀矿研究工作的重要内容。作者基于文献调研、野外地质调查和井震解释,对柴达木盆地七个泉背斜狮子沟组与七个泉组构造-沉积演化过程及其与砂岩型铀矿成矿的联系开展研究。研究认为:(1)狮子沟组富泥质砂,呈现退积旋回;七个泉组富砾,呈现进积旋回,底部与狮子沟组间发育新近系—第四系角度不整合,内部发育规模稍小的第四系内部角度不整合;狮子沟组—七个泉组发育由泥石流、下切沟道—充填和片流沉积构成的大型冲积扇,其中砂质层中密集发育地震变形构造。(2)新近纪以来最剧烈的构造抬剥事件发生在新近纪—第四纪之交,由此形成了新近系—第四系不整合并奠定了七个泉背斜构造格局。(3)推测七个泉背斜狮子沟组砂岩型铀矿潜在铀矿化段主要形成于新近纪—第四纪构造抬剥事件中,该事件催生出含矿构造,并加大了源区铀通量,最终控制了潜在铀矿化段形成发育和空间展布。新近系—第四系不整合则可作为预测潜在铀矿化段空间展布的关键构造控矿标志。同时,冲积扇扇中/扇缘中砂砾岩百分含量介于20%~50%之间的砂(砾)泥互层带可作为关键沉积控矿标志。研究成果可以为青藏高原东北缘盆地分析提供沉积学和地层学证据,对理解柴达木盆地其他背斜砂岩型铀矿形成发育过程具有重要价值。

综合测井资料在福泉大湾磷矿富水性特征分析中的应用

水文地质条件是矿山勘探过程中一项极其重要的工作,水文地质工作的好坏决定了后期矿山开采的经济性和安全性,准确地对地层富水性进行划分,则是水文地质勘查中重要的一环。在贵州白岩背斜地区以往的磷矿勘查中,人们通常笼统的将整个灯影组作为含水层,从而使得计算的涌水量远大于实际,给矿山的防水治水带来了极大的浪费。本文通过综合地球物理测井方法对大湾矿区地层的富水性进行研究,并定量的划分出勘查区内地层富水性,从而为水文地质勘查提供准确的物探依据。

潜伏背斜精细建模及其应用效果分析——以川东石炭系气田为例

四川盆地川东高陡构造带油气勘探对象主要以背斜圈闭为主,因大多数地面背斜出露石灰岩,保存条件差,天然气勘探价值不高,而潜伏背斜保存条件良好,成为天然气聚集的有利场所。川东地区石炭系气藏是构造圈闭型,落实圈闭形态十分重要,直接关系钻探获气成功率。目前,石炭系潜伏背斜天然气勘探开发已进行到深入挖潜阶段,但仍有一些潜伏背斜地震成果不落实,井—震深度误差大,值得人们深入研究。依据地震剖面、地面地质、钻测井资料,建立精细潜伏背斜模式,划分为4大类、7亚类及30个小型,并对4大类潜伏背斜勘探开发效果进行总体评价。基于新建潜伏背斜模式,在3方面得到应用:①基于潜伏背斜模式,进行模型正演和反演,有利于分析复杂波长、时间域构造畸变现象及高点偏移规律;②有利于建立合理的时深转换及叠前深偏速度模型,提高深度域构造形态的可靠性;③基于潜伏背斜模式的水平叠加时间剖面(简称叠加剖面)基本反射特征,从而判定陡潜背斜的基本类型和形态,避免深度域里造成“假潜伏背斜”。川东地区新的潜伏背斜精细建模,将在石炭系气藏深入挖潜中进一步发挥积极作用。

塔里木盆地东北缘吐格尔明背斜和阳北断裂带构造分析

吐格尔明背斜和阳北断裂位于塔里木盆地北缘,南天山山前库车褶皱冲断带的东段,两者均为基底卷入型构造。阳北断裂是一个反转构造,其变形历史可以追溯到侏罗纪—白垩纪的正断层;新生代构造反转,发生了多期冲断变形加速期,分别发生于白垩纪末—古近纪初、古近纪末—新近纪初、中新世早期、上新世和第四纪。吐格尔明背斜构造带是阳北断裂中新世早期及以后的冲断作用派生出来的一个次级基底卷入型构造变形带。它由吐格尔明背斜及其南、北两条呈背冲关系的逆冲断层组成。背斜核部元古宇变质岩出露地表;中、新生界直接不整合于变质岩之上,缺失全部古生界,说明研究区可能属于一个长期存在的古生代古隆起。

褶皱变形区正负向构造单元页岩气差异富集特征

四川盆地是中国西南地区一个具有多方位逆冲推覆构造背景的叠合型盆地。四川盆地南缘在多期次的构造叠加和改造作用下,地层的褶皱变形、破裂程度和抬升剥蚀程度均有较大差别,同一构造褶曲程度在局部应力场的影响下会呈现出一定的差异。研究区位于四川盆地南缘的褶皱变形区.

东海盆地西湖凹陷南部火成岩发育区G构造油气成藏特征

G构造是一个大型挤压反转背斜,位于西湖凹陷西南角的天台斜坡带火成岩发育区。由于目前对该区火山活动规律及后期油气保存等成藏演化条件认识不清,严重限制了天台斜坡带的油气勘探进程。通过对研究区地震资料进行解释,研究了G构造区火成岩的岩石学、年代学和时空分布特征,重建了火山活动、圈闭形成与油气成藏过程的关系。结果表明,G构造范围内发育的火成岩为中新世中期的浅层侵入岩、溢流相喷出岩和通道相火成岩,该火成岩的发育使得平湖组和花港组的地层碎裂化,由于该背斜核部存在早期火山通道,后期挤压形成的圈闭有效性差。龙井运动(中新世末期,5.3 Ma)至上新世三潭组沉积期,该背斜转折端发育了一系列近EW向次级断层,进一步破坏了圈闭的完整性。由于背斜翼部未受火成岩影响,该处的构造-岩性圈闭应该是下一步勘探的重要方向。

1∶5万重磁调查在广西南丹县罗富背斜的应用研究

罗富背斜位处丹池矿带大厂矿田外围,具有成矿地质条件相似,重磁异常相对突出,是潜在的成矿及找矿远景区,但目前尚未取得找矿突破。通过在罗富背斜开展1∶5万重力工作,圈定了罗富背斜泥盆系底部界面的形态特征,通过分析发现罗富背斜基底面的隆起轴向和泥盆系盖层背斜轴向(北西走向的重力高异常带)存在不一致,造成了泥盆系盖层背斜轴向往西偏移,盖层皱褶的形成往往伴随相应发育的断裂带、层间裂隙以及背斜轴部的张裂,这些地质构造为岩浆的侵入、热液的传输提供了前提,为成矿提供了容矿空间,该北西走向的重力高异常带(推断为泥盆系盖层背斜)被认为重要的控矿构造。

西湖凹陷中央背斜带中南部区带油气成藏主控因素与勘探方向

西湖凹陷深层—超深层油气资源勘探潜力大,具有良好的勘探前景。为明确西湖凹陷中央背斜带中南部区带的油气成藏主控因素,对西湖凹陷中央背斜带的构造背景、沉积特征、烃源岩条件和储层性质进行分析研究。通过分析西湖凹陷中央背斜带中南部不同区带油气分布特征,总结了油气富集的分布规律以及差异成藏的主控因素,建立了成藏模式。结果表明,西湖凹陷中央背斜带中南部的油气成藏主控因素为早期通源断裂与砂体耦合及晚期保存条件,并根据储盖组合及油气分布规律划分为平湖组、花港组、龙井组3个成藏组合,其中花港组是主要的成藏层系,花港组具备发育岩性体的沉积环境,具有岩性、地层圈闭形成条件;烃源岩持续生烃提供了充足的油气源,深层—超深层砂岩储集性能依然保持较好,在3900~3700 m低渗储层广泛发育,有利沉积相带叠合次生溶蚀控制优质储层分布,油气充注与圈闭的形成时间配置关系好。研究结果对于西湖凹陷的持续勘探开发具有一定的指导意义。

The Unique Folding Style in the Zagros Simply Folded Belt, the Kuh-e Qazi Anticline, South Iran

The study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin (175 km from Persian Gulf). The Zagros fold-thrust belt is home to one of the largest petroleum producing reservoirs in the world. Structures in this area have complications and the study anticline has unique structures in the Fars region. In the study area, the Kuh-e Qazi anticline due to special fold style and rotation toward Northeast is the unique structure between anticlines of the Zagros belt. This anticline is fault bend fold and plunge of the anticline in eastern part rotated toward Northeast along with the Nezamabad fault trend. In this area, the Kuh-e Qazi anticline has asymmetric structures and some faults such as the Nezamabad and the Sarvestan strike slip fault effect on this anticline. The geometry of anticlines in the Zagros fold-thrust belt is affected by the type of deformation and mechanical behavior of stratigraphic units specially detachment units. The purpose of this research is to determine of folding pattern of the Kuh-e Qazi anticline and define structural features affected on them in the study area. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply Folded Belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. Also, we use some software as Global Mapper and Tectonics FP for preparing some data.?Based on the research, which have been done, the boundary between ductile and frictional substrates causes rotation as a result of lateral, along-strike migration of the ductile substrate. The ductile or viscose layer in the study area is Hormuz Series. Due to lack or thinning of Hormuz salt over the Gavbandi basement high and in the eastern side of the Nezamabad basement fault, causes translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest unlike foreland basin due to the Nezamabad fault activity. This style between all of the anticlines in the study area is unique that rotates unlike foreland basin. In addition, influence on anticlockwise rotation, extensional stress has been created and then salt dome cropping out in Southeast of the Kuh-Qazi anticline. One of the best evidence for effect of extensional stress is triangular facets in this part of the study anticline. Based on folding analysis (geometry of axial plane and fold orientation), it is clearly confirmed that the translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest has been formed by basement fault activity as the Nezamabad fault in the boundary between ductile and frictional substrates of the study area.

Folding Style of the Kuh-e Siah Anticline in the Sarvestan Area, Interior Fars, Zagros, Iran

The Kuh-e Siah anticline is located in the Sarvestan area of the Fars province (186 km to Persian Gulf) and Interior Fars sub basin. This anticline is a fault bend fold and is located in the Sarvestan fault zone with Northwest-Southeast trend. The Sarvestan fault zone has caused main deformation by dextral strike slip activity in southern part of the Zagros fold-thrust belt. The main aim of this paper is to determine of fold style elements and folding pattern of the Kuh-e Siah anticline. This paper presents part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. In addition, we used some software as Global Mapper and Tectonics FP for prepared some data. Folds, which are close sideways, are neutral and these require special attention. It is remarkable that, in all sections of the Kuh-e Siah anticline, fold type is close and in the middle part of the anticline, fold type is different with other parts. In the middle part, fold type is upright-moderately gently plunging. On the other hand, in northwestern and southeastern parts fold type is similar together. These results maybe show that fold style follow that fold sigmoidal shape that created with two-fault segment of the Sarvestan fault zone in the study area. Therefore, it seems that the Kuh-e Siah anticline has suffered high deformation in the Sarvestan fault zone and this fault zone has created shear zone.

The Elements of Fold Style Analysis in the Khaftar Anticline, Zagros, Iran

The Study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin. The Khaftar anticline is located in the West, North-West of Jahrom city in the Fars province (148 km distance from Persian Gulf). The trend of Khaftar anticline has three orientations, consist of North-Northeast, East-West and South-Southwest. This anticline has asymmetric structure and some faults with large strike separation observed in this anticline. In the study area, stratigraphic units are affected by many faults in this area. Also one salt plug cropping out in the middle part of the Khaftar anticline. Maybe this salt plug affected on the stratigraphic units and geometry of structure. Description of fold geometry is important because it allows comparisons within and between folds and allow us to recognize patterns in the occurrence and distribution of fold systems. The main aim of this paper is determination of fold style elements and folding pattern of the Khaftar anticline. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on satellite images, geological maps, and well data. Some data, such as geological maps and geological regional data were prepared and provided by the National Iranian Oil Company (NIOC). Because of the Khaftar anticline, has complex structure, the analysis of fold style elements is seems necessary. Therefore, in further studies on this structure the changes of fold style elements will be analyzed and investigated from east to west in the different parts of this anticline. The activity of Nezamabad sinistral strike slip fault in the Khaftar anticline causes changes of axial plane characteristics and fold axis. Some of the results such as folding style analysis, how position of salt plug, changes of fold type and main structural changes (rotation of fold axis and 2.5 km displacement in this anticline) show main changes in the middle parts of the Khaftar anticline. It seems that, these changes have formed by activity of the Nezamabad fault and this fault’s activity same as fault zone.

Structural Style in the Khalfani Anticline, Coastal Fars, Zagros Fold-Thrust Belt

The Khalfani anticline is located in the Coastal Fars (Zagros, adjacent Persian Gulf). This anticline with Northwest-Southeast trend is a fault bend fold. In the study area, the Khalfani anticline has increased elevation from West to East with three distinct humps. The major faults in the study area are the Hendurabi and the Razak sinistral strike slip faults. Because analysis of fold and their folding styles in different parts system is important, the analysis of folding style elements is necessary for structural studies. The main aim of this research is structural style analysis based on fold style elements in the Khalfani anticline. This analysis is important for progress in hydrocarbons exploration in the Coastal Fars area. In this research, we used Tectonics FP and Global Mapper Software for preparing some data in our study. In addition, we used the common classification of folds for our research. Based on given results, the folding pattern of this anticline has indicated that the fold style is same in different parts of the Khalfani anticline. In the study area, based on classifications of fold in different methods, fold style is same together. Fold, with close sideways requires special attention as structural view;then the Khalfani Anticline with close style in all parts has special deformation and folding style. It seems that in the study area, folding style and variation of structural style have been created by effect of the Razak and the Hendurabi sinistral strike slip fault. Because these faults are basement or deep-seated faults, special folding style and special deformation can be formed in the study area. In addition, the Khalfani anticline in the study area has restricted within the Razak and the Hendurabi sinistral strike slip faults.

Structural Style in the Zagros Fold-Thrust Belt: The Gavbast Anticline, Coastal Fars

The Gavbast anticline is located in the Coastal Fars area of the Zagros folded belt, with north-south trend. The study anticline is restricted to the Bavush and Paskhand anticlines from North, the Gezzeh and Dehnow anticlines from South, the Varavi anticline from West and Nakh anticline from East (Figure 1). Description of fold geometry is important because they allow comparisons within and between folds and pattern-recognition in addition to occurrence and distribution of fold systems. The main goal of this paper is to define folding style of the Gavbast anticline and define structural features affected on them in the study area. In this research, we used the Tectonics FP software, Global Mapper software and geological maps and reports of Iranian National Oil Company. In addition, we used common classification of fold for indicating of folding mechanism of the Tabnak anticlinal structure. In the Gavbast anticline, fold style elements in all parts of this anticline have been calculated and analyzed for indicating of folding style mechanism. The results of this method have been shown the folding geometry changes accurately. The Gavbast anticline is gentle in structural sections D-D' and G-G' to K-K'. The anticline is an open fold in the L-L' section. Also fold type in the E-E' and F-F' sections of the Gavbast anticline is steeply inclined sub-horizontal. These sections are located between the Razak (western part) and Hendurabi fault (eastern part). It seems that E-E' and F-F' parts in the Gavbast anticline have been suffered most deformation affected by the Razak and Hendurabi faults. At the end of, it seems that, the Razak and Hendurabi faults have major effects on folding style. This structure is a very good sample for effect of strike slip faults on the folding geometry and for this reason;the Gavbast anticline is considered a special structural style in the Zagros fold-thrust Belt.

The Discovery of Deep Potassium and Lithium Resources in the Huangjinkou Anticline, Northeast of Sichuan

Objectives Important clues have been found for potassium prospecting in the Huangjinkou anticline of the northeast Sichuan Basin in the 1970s(Zheng et al.,2015;Lin et al.,2004).In 2008,China Geological Survey launched a prospective investigation of potash resources in the western region of China,and the local governments and private-owned enterprises also responded positively.Then,