东海盆地西湖凹陷构造样式及其演化

西湖凹陷是经历多期构造作用的白垩—第三纪盆地。多期裂陷和反转构造作用的叠加导致了相对复杂的构造格架样式和盆地地质结构。凹陷总体上具有东西分带,南北分块的构造格局。裂陷期的同沉积断裂组成了多种复合的构造样式：西部斜坡带主要发育断阶、地堑和地垒构造;中央洼陷带则以复合“Y”字型、羽状和似花状断裂组合为主;东缘断阶带主要发育“Y”字型、梳状和羽状组合。坳陷反转期,早期的同沉积断裂发生了不同程度的逆冲反转,形成了多种复合的构造样式,例如反冲叠瓦扇构造、后断叠瓦式逆冲构造等叠合构造样式。从盆地的构造样式出发,探讨了盆地的形成演化和构造- 沉积充填过程对有利圈闭带发育分布的控制作用,对富生烃凹陷油气预测具有重要指导意义。     

Effect of tidal stress on fault nucleation and failure of the 2007 Ms6.4 Ning’er earthquake

Based on calculations of the tidal Coulomb failure stress and investigations of the correlation between the Earth tide and the Ning’er earthquake sequence, the processes of fault nucleation and failure were simulated. In these simulations we consider the influence of tidal stresses using the rate- and state-dependent friction laws. Furthermore, the effects on tidal triggering due to the stress amplitude and periodic oscillation properties were investigated, and the triggering effects between the tidal normal and tidal shear stresses were compared. The results showed that the Ning’er earthquake sequence was a physical consequence of tidal effects. A transition period T₀ exists between the nucleation and failure processes of a seismic fault. When the period T of stress is equal to or becomes larger than T₀, the fault response becomes dependent on the periodic features of the loading stress; however, for T < T₀, the response of the fault is nearly independent of the period. Both the tidal normal and tidal shear stresses have similar effect in the nucleation and failure processes; the clock changes generally increase with the maximum amplitudes of the tidal stresses. Tidal normal and tidal shear stresses with positive amplitudes mainly induce earthquake triggering; however, the triggering effects induced by negative tidal stresses are smaller and faults are not sensitive to negative tidal stresses. Our results primarily reveal the physical mechanisms of tidal stress triggering.     

Recurrence of paleoearthquakes on the southeastern segment of the Ganzi-Yushu Fault,central Tibetan Plateau

Although there are many earthquake relics preserved in the southeast segment of the Ganzi-Yushu Fault in the central Tibetan Plateau,the recurrence regularity of paleoearthquakes is not yet clear.This work studies paleoearthquakes on this fault segment since the Holocene through geomorphic investigation and trench excavation.The results show that sinistral dislocation of the T3/T2 terrace boundary is up to 80 m at the Cuoa Township.A 1.5 m-high fault scarp extends 3 km near the Renguo Township.A number of paleoearthquakes are exposed in trenches at two places,respectively.In combination with historical records,our work has identified 5 or 6 paleoearthquakes on this fault segment since last 5600 years.The occurrence times and recurrence intervals of these paleoearthquakes are estimated by 14C dating on strata in the trenches.Our analysis shows that these paleoearthquakes do not exhibit evident periodicity,but instead show a clustering characteristic.From 5600 a to present,seismicity of the southeastern segment of the Ganzi-Yushu Fault has two active periods and one quiet period,and the present-day time is just in the second active epoch.The recurrence intervals of each active epoch are different:1000-1300 a in the first one,534 a in the second one.     

基于等效误差方程的三线阵CCD影像自检校区域网平差

本文针对机载三线阵CCD影像自检校区域网平差中,待求未知参数众多、法方程巨大而复杂的问题,提出了基于等效误差方程的ADS40影像自检校区域网平差方法。通过采用虚拟误差方程对原始误差方程进行等效改化,构建ADS40影像自检校区域网平差的等效误差方程,从而消去加密点地面坐标改正数,减少平差待求参数,实现法方程的合理简化。试验证明此方法可在保证平差精度的同时,显著提高解算效率。     

广东连州长兴期含煤地层

九陂组(亚田煤组)是粤北和湘南晚二叠世重要的含煤地层,其下伏"梅田灰岩"的涵义和(虫筵)化石Gallowayinella meitienensis的层位问题曾长期未得澄清.通过对梅田组剖面的详细工作,建立了下部的Gallowayinella组合和上部的Nanlingella jiaozishanica-Sphaerul...     

塔里木盆地奥陶纪碳酸盐岩台地的层序结构演化及其对盆地过程的响应

塔里木盆地奥陶纪的碳酸盐岩台地发育有长达3千余千米的台地边缘带。通过综合大量的地震、钻井及野外剖面的分析,奥陶纪碳酸盐岩系中识别出4个以不整合面为界的复合（二级）层序。它们均显示出从上超的水进沉积到进积或加积的高位域的沉积结构。其内可进一步划分出10个沉积层序或三级层序。它们的组合和分布决定着碳酸盐台地沉积层序结构的基本特征。沉积层序的水进早期或高位域晚期以颗粒灰岩、生物灰岩等沉积相组合为主;而水进期或高位域早期则以泥晶-粉晶灰岩、簿层白云质灰岩等沉积相组合为主。古地貌恢复并结合钻井资料的沉积相分析揭示出,盆地东北部早、中奥陶世的碳酸盐岩台地边缘的分布受到满加尔深水凹陷的边缘斜坡带古构造地貌的控制,形成一向西凸的弧形碳酸盐岩台地边缘带,沿台地边缘发育有礁-滩沉积复合体。中奥陶世的构造古地理变革使盆内的碳酸盐岩台地分异成塔中、塔北、塘南等多个孤立台地,并由深水、半深水的凹陷所分隔。台地边缘的发育和分布常受古隆起边缘的控制。沿台地边缘的礁、滩相带为重要的有利储集层发育带。中奥陶统中央隆起带缺失中奥陶世早期和晚奥陶世早期沉积,并形成了大范围分布的喀斯特岩溶不整合面。喀斯特岩溶体系以发育垂向的、由断裂控制的串珠状洞穴和多层状分布的岩溶洞穴为特征。
     跨盆地不同构造带的井-震结合解释剖面的追踪对比表明,盆内与二级、三级层序对应的海进-海退旋回是同时变化的,并与Haq的海平面变化曲线可对比。这反映出盆地范围的或全球海平面变化对沉积旋回结构的发育具有控制作用。盆地西缘露头剖面和盆内钻井岩心的碳、氧同位素分析也为海平面变化的旋回结构分析提供了制约。主要海平面下降期的氧同位素δ18O都发生了明显的正偏。盆内晚奥陶世的海平面总体是呈上升趋势的,晚奥陶世中期海平面的上升导致了盆内碳酸盐岩台地的总体淹没。     

Early Paleozoic ridge subduction in the Chinese Altai: Insight from the abrupt change in zircon Hf isotopic compositions

Zircons were separated from granitoids, gneisses, and sedimentary rocks of the Chinese Altai. Those with igneous characteristics yielded U-Pb ages of 280-2800 Ma, recording a long history of magmatic activity in the region. Zircon Hf isotopic compositions show an abrupt change at ~420 Ma, indicating that prior to that time the magmas came from both ancient and juvenile sources, whereas younger magmas were derived mainly from juvenile material. This may imply that the lithosphere was signifi- cantly modified...     

阿尔金南缘中段清水泉斜长花岗岩同位素年龄及成因研究

阿尔金南缘清水泉地区与基性-超基性岩伴生的花岗岩为斜长花岗岩。岩石地球化学显示该花岗岩高硅、富铝和钠,低镁和钾;轻稀土富集,具有Eu的正异常(δEu为1.01~2.01)。岩石富Rb、Ba,特别高Sr(779×10-6~864×10-6),低Y(1.17×10-6~1.51×10-6)及Yb(0.15×10-6~0.20×10-6),强烈亏损Nb、Ta等。斜长花岗岩锆石振荡环带清晰,Th/U和Nb/Ta比值分别为0.38~0.52,2.92~5.04;具有明显的Ce正异常和Eu负异常,为典型的岩浆锆石,利用LA-ICP-MS微区原位定年获得该花岗岩206Pb/238U-207Pb/235U谐和年龄为465Ma,206Pb/238U加权平均年龄为451±4Ma。锆石饱和温度计和锆石Ti温度计演算结果显示锆石的结晶温度分别为783~811℃和693~821℃。推测花岗岩源区压力范围为1.8~2.0GPa,形成深度在60km以上。综合分析清水泉花岗岩主、微量元素地球化学特征,并结合区域地质,认为该花岗岩属"I"型花岗岩,由地幔基性岩浆上侵分异形成,产于伸展环境。     

西藏斑岩铜矿的前景展望

世界斑岩铜矿主要产于中生代一新生代环太平洋带、古特提斯带和古生代中亚—蒙古带，因为上述3带为聚合板块集中分布地区。中国西藏集中了金沙江聚合带、雅鲁藏布江聚合带和怒江—班公错聚合带，为世界上聚合板块最发育地区之一，具有较长的大洋板块俯冲和陆—陆碰撞的造山历史，构造—花岗质岩浆十分发育，其中深源高侵位的花岗质斑岩分布广泛，对于形成斑岩铜矿和其他相关矿床十分有利，为找矿评价斑岩铜(金)矿很有前景的地区。笔者借鉴世界和中国评价斑岩铜矿的经验，同时收集了西藏近年来找寻评价斑岩铜矿有关的地质资料，对西藏斑岩铜矿的前景进行了展望。     

扰动方式对水华微囊藻(Microcystis flos-aquae)群体大小的影响

风浪扰动是影响湖泊生态系统的重要环境因素之一.为了解扰动方式对微囊藻群体大小的影响,在实验室可控条件下,模拟不同扰动方式（持续扰动和间歇扰动）对太湖水华微囊藻（Microcystis flos-aquae）群体大小的影响.结果显示,间歇扰动组水华微囊藻群体从35.09 μm迅速增大至43.73 μm,实验第17天时为59.00 μm;而持续扰动组水华微囊藻群体大小先从35.07 μm增大到43.51 μm,实验第17天时减小至13.95 μm;不扰动组整个实验期间群体大小相对稳定,实验初为35.38 μm,实验第17天时为33.67 μm.方差分析显示,间歇扰动组群体大小显著大于持续扰动组和不扰动组,持续扰动组显著小于不扰动组.实验第17天时间歇扰动组藻细胞密度（1.675×10⁶ cells/ml）显著高于持续扰动组（0.344×10⁶ cells/ml）和不扰动组（1.461×10⁶ cells/ml）.研究结果表明,适当强度下的间歇扰动能促使水华微囊藻群体显著增大和生长,而长时间的持续扰动则会抑制水华微囊藻群体的聚集和生长,该结果有助于人们对太湖微囊藻水华暴发机理的认识.