Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching

The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and evolution. As sensitive markers of small stress changes, joint and shear fracture, characterized by consistency of orientation over wide area, can be used to reconstruct paleostress state and its evolution. Detailed observations and analysis on the orientations, geometrical patterns, sequences of joints and shear fractures and their chronological relation to faults and folds show that, the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different orientations. And the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different orientations. According to the relationships between joint and shear fractures and stress, the NEE-SWW systematic joints are inferred to result from lateral weak extension caused by the late Cretaceous regional uplift, while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the Neogene. But some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa depression. At the beginning of the Neogene, the stress field changed and the maximal principal stress σ1 switched from vertical to horizontal.     

四川盆地川西坳陷高异常地层压力分布特征

本文通过分析川西坳陷２０多个含气构造的主要地层压力资料,对川坳陷高异常地层压力的分布特征有了一定的认识。认为川西高异常地层压力在纵向层位上主要分布于侏罗系和上三叠统,压力分段明显,相同的力段在不同的构造既不等时也不等深;在平面上高异常地层压力分布广泛,超高压区刚分布于川西北地区,并形成两个超高压中心,整个高异常地层压力的分布虽然总体上基本一致,但在不同层位,不同时期也存在着差异。     

Subsidence history and forming mechanism of anomalous tectonic subsidence in the Bozhong depression, Bohaiwan basin

The Bozhong depression of the Bohaiwan basin belongs to a family of extensional basins in East China, but is quite different from other parts of the basin. The Cenozoic subsidence of the depression is controlled by a combination of lithospheric thinning and polycyclic strike-slip movements. Three episodic rifts have been identified, i.e. Paleocence-early Eocene, middle-late Eocene and Oligocene age. The depression underwent syn-rift and post-rift stages, but two episodic dextral movement events of the strike-slip faults modify the subsidence of the Bozhong depression since the Oligocene. The early dextral movement of the Tan-Lu fault associated with crustal extension resulted in accelerated subsidence during the time of deposition of the Dongying Formation with a maximum thickness of 4000 m. A late reactivation of dextral movement of the Tan-Lu fault began in late Miocene (about 12 Ma), which resulted in the intense subsidence of Minghuazhen Formation and Quaternary. In addition, dynamic mantle convection-driven topography also accelerated the post-rift anomalous subsidence since the Miocene (24.6 Ma). Our results indicate that the primary control on rapid subsidence both during the rift and post-rift stages in the Bozhong depression originates from a combination of multiple episodic crustal extension and polycyclic dextral movements of strike-slip faults, and dynamic topography.     

惠民凹陷孔店期盆地原型格架对油气成藏的影响

为了准确评价惠民凹陷古近系孔店组的油气资源,研究盆地原型格架对油气成藏的影响是一个重要的方面.首先对盆地的构造演化进行分析,发现受构造演化的影响,孔店组不同时期的厚度(或残留厚度)在凹陷不同部位有所不同,导致主力烃源岩生烃条件发生变化;孔店期原型盆地为北断南超的伸展半地堑,盆地长轴方向整体为近东西向,主要的控制性断层是凹陷北部的边界断层-滋镇断层和阳信断层;通过计算盆地的残余厚度和剥蚀厚度,恢复了原型盆地的厚度,孔二亚段地层向南部斜坡带超覆,发育3个沉降中心,分别位于滋镇和临南洼陷东北部及阳信洼陷,孔一亚段沉积具有继承性,但北东向的滋镇、阳信断层对地层的控制更为明显;沉积中心迁移的结果显示:孔二亚期-孔一亚期沉积中心迁移,对在滋镇和临南洼陷内孔店组地层油气成藏及阳信断层下降盘的储层中成藏有利,但孔一亚期-沙四亚期沉积中心的迁移,对油气在孔一-沙四段储层中成藏不利.     

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.     

塔里木盆地库车褶皱冲断带东段依奇克里克背斜的构造特征和形成演化

依奇克里克背斜位于塔里木盆地北缘,库车褶皱冲断带北部构造带东段。它是一个基底卷入型开阔直立背斜,是在晚海西期古隆起和印支期库车周缘前陆盆地前渊带背景下形成的一个含油气构造。背斜核部出露的最老地层是白垩系下统,向两翼方向依次出露古近系、新近系和第四系。钻井资料揭示,之下还有三叠系和侏罗系含煤碎屑岩建造,不整合于石炭系灰岩之上。中新统吉迪克组至更新统西域组是背斜的生长地层,古近系及以下地层是前生长地层。背斜位于库车褶皱冲断带根带,发育厚皮构造;向前锋方向,逐渐演变为薄皮构造。褶皱冲断带的两个主滑脱断层分别发育于侏罗系煤层和吉迪克组膏盐层。作为印度—亚洲碰撞的远程效应,背斜的变形起始于古近纪末—新近纪初,经多个变形加速期,脉式冲断,直至第四纪晚期才最终定型。

     

针刺法对抑郁症模型大鼠行为学的影响

目的：观察针刺法对抑郁症模型大鼠行为学的影响。方法：随机选取24只雄性大鼠制备孤养结合慢性不可预见性温和刺激抑郁症模型,造模成功后将其分为模型组、氟西汀组、针刺组,每组各8只。随机选取正常雄性大鼠8只作为空白对照组。空白对照组、模型组每日上午9∶00予0.9%氯化钠注射液灌胃;在此基础上,针刺组予百会穴、关元穴针刺干预;氟西汀组每日上午9∶00予以氟西汀药液1.8 mg/kg灌胃。分别在干预的第1、7、14、21、28天对各组大鼠进行Morris 水迷宫测试,记录大鼠自我修饰、区域探视、跟随同伴、身体接触的次数,观察大鼠行为学及学习记忆的情况。结果：干预后,模型组、氟西汀组、针刺组大鼠潜伏期明显高于空白对照组（P＜0.05）,且干预第21天,氟西汀组、针刺组潜伏期低于模型组（P＜0.05或P＜0.01）。模型组、氟西汀组、针刺组大鼠干预第7、14天水迷宫穿过平台次数少于空白对照组（P＜0.05）,且针刺组与模型组第1、14、21、28天比较,差异有统计学意义（P＜0.05或P＜0.01）。模型组、氟西汀组、针刺组第1、21、28天跟随同伴次数、自我修饰次数、同伴身体接触次数、区域探视次数均少于空白对照组（P＜0.05）,上述指标,氟西汀组干预第14天与模型组同时间节点比较,差异有统计学意义（P＜0.05或P＜0.01）。结论：针刺法对抑郁症大鼠的行为学以及学习记忆有一定的调节和改善作用。     

鄂尔多斯盆地侏罗系延安组煤岩特征及其主控因素分析

盆地级宏观视角的煤岩特征研究,有助于深化盆地控煤理论、全面认识盆地演化过程,同时也对于煤层生物气、直接液化用煤、富油煤等资源的分布预测及整体利用规划具有参考价值。鄂尔多斯盆地侏罗系延安组煤炭资源丰富,经历了数十载的勘查和研究,积累了丰富的煤岩资料,可供开展盆地视角的煤岩特征研究。系统收集、整理了前人鄂尔多斯盆地延安组煤岩显微组分数据,并于宁东煤田、陕北侏罗纪煤田、黄陇侏罗纪煤田分别采取了代表性煤岩样品,开展了煤岩研究和元素地球化学分析。研究结果显示,鄂尔多斯盆地侏罗系延安组煤层具有富惰质组的特征,惰质组含量与镜质组含量相当,镜质组以基质镜质体为主,含少量结构镜质体、均质镜质体和团块镜质体;惰质组以半丝质体为主,含少量氧化丝质体、粗粒体和碎屑惰质体;壳质组以小孢子体为主,还有树脂体、角质体和木栓质体。煤岩组分在平面上呈环带状分布特征,从盆地边缘向盆地中心惰质组含量降低、镜质组含量增高。延安组各煤层呈中部煤层惰质组含量较低,向上部煤层和下部煤层惰质组含量增高。对比分析表明鄂尔多斯盆地延安组为典型的坳陷型盆地环带状聚煤模式,聚煤中心与沉积中心完全分离;远离盆地中心方向,泥炭遭受的氧化时间、氧化范围和氧化强度均逐渐增大,导致惰质组含量增高;反之,靠近湖盆方向惰质组含量减少。