从地震信息看阿尔金断裂带构造和塔里木盆地花彩弧断裂体系

阿尔金断裂带由多条断裂组成,主要有阿尔金断裂、且末断裂、三危山断裂。其中阿尔金断裂为主断裂,它呈左旋走滑兼具逆冲性质,中生代—古近纪为左旋走滑,新近纪由东南向西北逆冲推覆。且末断裂和三危山断裂均具左旋走滑性质。且末断裂受统一的阿尔金断裂带左旋应力场控制,但又叠加了塔里木台盆区向南挤压的应力场,从而具有双重属性。塔里木盆地的断裂总体上组成古生界塔北花彩弧断裂束和塔南花彩弧断裂束,展布成全盆地的菱形断裂系统,且末断裂构成其东南边界。在该菱形断裂系统的北弧顶和菱形内的中央轴部为背冲式的构造断裂带,显示挤压特征;在花彩弧两翼转弯处展布正花状构造样式,显示走滑特征。阿尔金断裂带及其两侧,主要在柴达木、塔里木两大盆地发现了大油气田,两者都是由断层控制油气的垂向运移与分布。柴达木盆地具有双重断—坳的特点,但油气田只分布在中—新生界构造层内;塔里木盆地,南北翘板式的构造运动是其形成复式油气区的最重要的地质构造条件。     

地下资源开采与诱发地震：现状与进展

页岩气、地热等清洁能源正成为全球能源开发日益重要的组成部分,也是我国未来能源产量增长的主体,对保障能源资源安全、支撑双碳目标意义重大。然而随着页岩气、地热等地下工业开采活动规模的不断扩大,由此引发的地震灾害问题正日益受到人们的关注。强化工业活动与诱发地震关系研究、管控相关诱发地震灾害风险成为全球面临的重要课题和挑战。基于此,笔者等调研了工业活动诱发地震的全球典型案例,系统介绍了不同国家(美国、加拿大和韩国)工业活动诱发地震的现状及其差异,并对流体注入诱发地震的主要途径、物理机制、相关作业参数和诱发地震关系等做了全面的综述。发现诱发地震不仅与流体注入参数(体积、速率等)相关,还受控于特定的区域地质背景和断裂条件。合理管控地震灾害风险、促进相关能源的开采,应该统筹开采区地质地球物理的综合调查和开采过程的动态监测。     

云南小湾断层泥中伊利石矿物特征及其意义

根据扫描电镜观察、Ｘ射线衍射和化学分析，研究断层泥中伊利石矿物的特征。研究表明，小湾断层泥中伊利石属Ｉ＋ＩＳＩＩ结构，膨胀层约占１５％，ＩＭ多型，层间阳离子２Ｃａ＋Ｎａ＋Ｋ≈１，伊利石的ｂ。值等于８．９９３Ａ，这些参数反映了小湾断层活动的机制为低压、低温（＜２００℃）。     

鲁西隆起北部磁村断层走滑特征及其控藏意义

盆地周边地质调查是研究盆地构造演化的一种重要补充手段,露头区断层活动规律可以直观分析盆地内观察不到的断层性质。本文主要研究了磁村断层的野外地质特征及其对沉积的控制,并类比了沉积盆地内的断层对沉积的控制。研究发现磁村断裂带内地质现象丰富,发现有擦痕、阶步、碎裂灰岩、牵引褶皱、石香肠构造、菱形构造等,其中石香肠构造和菱形构造受控于岩性及断裂带内局部应力场变化,与其他证据共同指示磁村断层为一条右旋伸展-走滑断层。在此基础上分析了磁村断层走滑活动模式及对沉积扇体的控制,并针对断层走滑活动的沉积响应,在沉积盆地内找到了多处伸展-走滑型断层和走滑-伸展型断层控沉积的沉积迁移现象,且发现了走滑伸展作用产生的斜歪扇背斜现象。这种控制作用使沉积砂体沿断层走向展布,进而控制油气成藏和分布。综合分析认为,磁村断层形成于晚中生代以来鲁西地块的张扭性应力场,是鲁西隆起不同块体差异伸展所致,起调节不同块体应变的作用。     

Evaluation of geological factors in characterizing fault connectivity during hydrocarbon migration: Application to the Bohai Bay Basin

Faults play an intricate role in hydrocarbon migration and accumulation since they can serve either as a conduit or a seal. Quantitative evaluation of fault opening/sealing properties requires the selection of valid and optimal parameters among numerous geological factors to characterize the hydraulic behaviors of faults. The present study focuses on the Chengbei Step-Fault Area in the Qikou Depression, Bohai Bay Basin, NE China, because hydrocarbon migration and accumulation in this area occurred in a relatively short period so that accumulated hydrocarbons can be used as an indicator to deduce hydraulic connectivity of a fault zone between two sites. Various geological parameters pertinent to a fault, such as burial depth, dip angle, throw, strike, percentage of sandstone of faulted intervals, fluid pressure in faulted mudstone, stress normal to the fault plane, and shale gouge ratio, are analyzed to assess their effectiveness in characterizing fault connectivity. An index, the fault-connectivity probability (N_p), is proposed to evaluate the possibility that a fault has been once serving as a migration pathway. The statistical relationship between N_p and any a geological parameter may be used to indicate the effectiveness of this parameter in characterizing the connectivity of a fault during hydrocarbon migration. The correlation coefficient of a relationship is a good indicator of the effectiveness; and the results are generally in agreement with qualitative assessments. Parameters representing a single geological factor are generally ineffective, whereas those representing implicitly or explicitly two or more factors, such as shale gouge ratio, stress normal to the fault plane, and fault opening index, are more effective.     

Fault system and thermal regime in the vicinity of site NGHP-01-10, Krishna–Godavari basin, Bay of Bengal

Drilling/coring activities onboard JOIDES Resolution for hydrate resource estimation have confirmed gas hydrate in the continental slope of Krishna-Godavari (KG) basin, Bay of Bengal and the expedition recovered fracture filled gas hydrate at the site NGHP-01-10. In this paper we analyze high resolution multi-channel seismic (MCS), high resolution sparker (HRS), bathymetry, and sub-bottom profiler data in the vicinity of site NGHP-01-10 to understand the fault system and thermal regime. We interpreted the large-scale fault system (>5 km) predominantly oriented in NNW-SSE direction near NGHP-01-10 site, which plays an important role in gas hydrate formation and its distribution. The increase in interval velocity from the baseline velocity of 1600 m/s to 1750–1800 m/s within the gas hydrate stability zone (GHSZ) is considered as a proxy for the gas hydrate occurrence, whereas the drop in interval velocity to 1400 m/s suggest the presence of free gas below the GHSZ. The analysis of interval velocity suggests that the high concentration of gas hydrate occurs close to the large-scale fault system. We conclude that the gas hydrate concentration near site NGHP-01-10, and likely in the entire KG Basin, is controlled primarily by the faults and therefore has high spatial variability.We also estimated the heat flow and geothermal gradient (GTG) in the vicinity of NGHP-01-10 site using depth and temperature of the seafloor and the BSR. We observed an abnormal GTG increase from 38 °C/km to 45 °C/km at the top of the mound, which remarkably agrees with the measured temperature gradient at the mound (NGHP-01-10) and away from the mound (NGHP-01-03). We analyze various geological scenarios such as topography, salinity, thermal non-equilibrium of BSR and fluid/gas advection along the fault system to explain the observed increase in GTG. The geophysical data along with the coring results suggest that the fluid advection along the fault system is the primary mechanism that explains the increase in GTG. The approximate advective fluid flux estimated based on the thermal measurement is of the order of few tenths of mm/yr (0.37–0.6 mm/yr).     

南海裂陷盆地中斜向伸展及其油气勘探意义

利用海上钻井、地震等资料,重新认识南海珠江口盆地文昌B凹陷控凹边界南断裂构造变形史及动力学机制,探讨油气勘探意义。研究表明,渐新世—中新世,南断裂具有斜向伸展性质,在倾向剖面,断裂带发育挤压褶皱和破碎主位移带的构造样式;在走向剖面,相关地层呈"厚薄相间"分布。平面上,发育雁列式背斜与洼地共生、"马尾状"断裂体系和右阶斜列阶步断裂体系。斜向伸展动力学机制受控于区域伸展构造应力场与先存南断裂走向。南断裂渐新世—中新世斜向伸展变形,控制和影响了油气成藏要素、流体相态。     

维西—景洪裂陷带初步研究

位于兰坪－思茅坳陷带西侧近南北向的维西－无量山－景洪地质块体，根据地球物理资料结合地质综合分析，具有裂陷带的特征，自泥盆纪开始的地幔上隆，形成隆起带，地壳产生东西向拉张，局部出现火山活动，石炭纪至三叠纪以中酸性为主的火山岩浆大量喷发，早侏罗世关闭，中新生代沉积厚大碎屑岩系，伴随裂陷带的生成，演化形成许多大中型矿床。     

帕米尔东北部木吉断层晚第四纪运动性质和滑动速率的约束

帕米尔造山带是印度-欧亚大陆会聚带的西构造结。木吉断层作为中-西帕米尔与东帕米尔的最北部边界转换断层,其运动性质和滑动速率的准确限定对于理解帕米尔现今应力状态和运动学特征等具有重要意义。本文以木吉断层东段布拉克村北位错特征显著的冰碛台地（39.2020°N,74.3910°E）为研究对象,基于高分辨率卫星影像解译、野外地质地貌调查、差分GPS测量和冰川漂砾宇宙成因核素¹⁰Be暴露测年,获得布拉克北冰碛台地形成（16.8±3.5 ka）以来木吉断层的累积右旋位错量、垂直位错量、南北向拉张量以及最小速率分别为约190 m、105±12 m、34±12 m和11.3±2.4 mm/a、6.3±1.5 mm/a、2.0±0.8 mm/a;三者的比值约为6：3：1,水平向的总滑动速率为11.5±2.3 mm/a。与位于断层中部近乎纯走滑的阿克萨依处相比,木吉断层在布拉克北以右旋走滑为主的同时,具有明显的正断分量。断层在布拉克北的水平向总滑动速率11.5±2.3 mm/a与阿克萨依处右旋走滑速率的最大值（9.4±0.9 mm/a）大致相当;因此尽管断层沿走向的运动性质发生了显著变化,其水平向滑动速率大致保持恒定。

     

云南金平长安金矿断裂控矿作用浅析

长安金矿矿体呈似层状、透镜状产于NE陡倾F6断层破碎带的东亚带砂泥质构造岩中,成矿期发生近EW向断裂的构造叠加,成矿之后又遭受到近EW向小断裂的破坏.F6断层破碎带西亚带具导矿作用,东亚带起到容矿的作用,成矿期叠加的EW向断裂（F7、F8、F9等）兼具导矿和容矿作用,侵入于F6断裂带中的细晶正长岩、煌斑岩、辉绿岩等岩浆活动所带来的成矿流体促使矿质富集,形成工业矿体,成矿期后近EW向断裂（F10-1、F10-2）和NNW、NE向小断裂（f）为破矿构造.据此把长安金矿断裂构造演化和成矿初步分为主控矿断裂成矿、叠加断裂成矿和后期断裂破矿三个演化阶段.