大兴安岭莫尔道嘎地区新元古代巨斑状碱长花岗岩地球化学特征

莫尔道嘎地区巨斑状碱长花岗岩是额尔古纳地块最早的岩浆活动的产物.对巨斑状碱长花岗岩的地质学、岩石地球化学特征进行了阐述,确定岩体形成于新元古代,属同碰撞期陆壳改造型钙碱性花岗岩.认为自新元古代开始,额尔古纳地块进入了强烈碰撞增生演化阶段.     

Numerical modeling of block structure dynamics: dependence of a synthetic earthquake flow on the structure separateness and boundary movements

A seismically active region is modelled as a system of absolutely rigid blocks separated by infinitely thin plane faults. The interaction of the blocks along the fault planes and with the underlying medium is viscous-elastic. The system of blocks moves as a consequence of prescribed motion of the boundary blocks and of the underlying medium. When for some part of a fault plane the ratio of the stress to the pressure exceeds a certain strength level a stress-drop (a failure) occurs (in accordance with the dry friction model), and it can cause a failure in other parts of the fault planes. In the model the failures represent earthquakes. As a result of the numerical simulation a synthetic earthquake catalog is produced. The numerical modelling was carried out for three types of structures with increasing of the structure separateness inside of each type and for two types of boundary movements. A synthetic earthquake flow is characterised by several features including the frequency-magnitude relation (the Gutenberg-Richter curve). When the structure separateness increases the slope of the curve changes monotonously in the same direction for all considered types of structures if the boundary movement is the same. The directions of changing of the slope are opposite for two considered boundary movements.     

广西北流地震震源区短周期密集台阵背景噪声成像

作为构造上较为稳定的华南地块,其地震活动相对中国西部明显偏低,但也发生过多次中强地震.华南中强地震震源区深部结构对于深入研究华南板内地震成因具有重要科学意义.2019年发生在两广交界的北流5.2级地震是近年来华南最大的一次中强地震,该次地震的发生也为我们研究华南地震震源区深部结构提供了理想场所.本文基于120个短周期地震仪组成的密集台阵背景噪声资料,通过互相关提取了1~5 s高频面波频散信号,然后采用面波直接反演法,对北流地震震源区进行地下6 km深度范围内浅层地壳速度结构成像.结果显示：浅层地壳剪切波速度横向变化强烈,速度分布不均匀;低速异常主要分布于三条断裂带周围;研究区存在NNW-SSE向的高速异常,该高速异常与震中区高速异常相交在水平方向上呈"L "形环绕分布于石窝断裂南东侧;震中上方为上凸形态的高速异常,这些高速异常可能为中生代花岗岩基,结合研究区现今NW-SE向的构造应力场分析：石窝断裂南西盘向南东方向运动时受到" L"形高速体阻挡,可能导致应力积累,进而引发地震.此外,这种局部异常高速体可能是华南"马赛克"结构中微陆块在上地壳中的延伸,上地壳结构的不均匀性和大尺度构造相互作用,会在局部区域导致应力积累,从而引发中强地震,这也可能是华南板内地震发生的一种重要成因机制.     

山东七宝山多金属矿区敞沟矿段Ⅰ号脉铅锌矿化赋集规律研究

敞沟矿段位于山东五莲七宝山多金属矿区矿区中南部,共由10条多金属矿脉组成,产于次火山岩体内侧,其中以Ⅰ号铅锌矿体规模最为大,矿体主要延伸方向为近东西,倾向南西,倾角变化较大,35°~80°不等。采用OPIS软件,对控矿构造及矿石品位等的主要矿化指标进行趋势预测与分析,通过各个矿化指标的等值线图分析结果表明,对Ⅰ号铅锌矿体矿化富集规律进行简要描述,结合矿体形态变化,最终得出两个可能的找矿区域,G710线中浅部,标高约-50~180 m区域,G707线中深部,标高约-150~-290 m区域。     

华北陆块2.56～2.52 Ga增氧事件对成矿和生命演化的影响

地球表层大气氧浓度的显著增高是地球史上最重大的地质事件之一,它不仅改变了地球表层环境,促进了生命演化,而且加速了表生地质过程,形成一系列适应环境突变的岩石和重要矿床。地球在前寒武纪时期曾发生过两次大气快速增氧事件,分别为大氧化事件(GOE)和新元古代氧化事件(NOE)。本文主要论述华北陆块新太古代晚期增氧事件的时限及其对成矿和生命演化的影响。华北陆块新太古代晚期形成千余个氧化物相BIF型铁矿床和矿点,属于阿尔戈马型,累计查明资源储量约335.36亿t,占全国铁矿总资源储量46%。该类矿床和矿点形成于弱碱性氧化环境,成矿时代主要介于2.56～2.52 Ga,并经历了2.51～2.50 Ga的变质作用。通过对BIF型铁矿床中矿石的Ce异常、铁同位素组成和硫同位素非质量分馏效应(MIF-S)等特征研究,显示在2.56～2.52 Ga期间大气圈的氧浓度大幅度升高,并由缺氧还原环境变为具一定氧浓度(1%～10%PAL)的氧化环境,暗示华北陆块在此期间曾出现过一次显著的增氧事件。其对华北陆块的成矿作用产生了重要影响,主要表现在以下三个方面:(1)形成大量氧化物相BIF型铁矿床,这是中国最重要的铁矿...     

用于运动估计的高效三步法的VLSI实现

根据高效三步法的特点,提出了有效的数据流和相应的VLSI结构。该数据流充分利用参考帧搜索点之间数据重叠的特征,以减少数据存储器访问的次数,从而减少了运动估计中功率消耗最大部分的操作。通过对各种测试序列的仿真证明,该VLSI结构有效地实现了高效三步法,适合MPEG-4和HDTV应用。     

云开地块北缘MORB型火山岩的首次发现及其大地构造意义

最新研究发现,在云开地块北缘陆川县石窝镇-北流市清水口镇一带的"云开岩群"中出露一系列变质基性火山岩,该火山岩总体呈北东向带状分布,主要岩性为斜长角闪岩和斜长角闪片麻岩,局部岩石中还夹有少量呈透镜状、布丁状或似层状产出的石榴辉石岩、透辉石岩、透辉角闪石岩、角闪石岩、(含石榴)斜长角闪岩、角闪绿帘石岩、石榴阳起石岩、石榴斜长辉石岩等.地球化学研究表明,其为典型的大洋拉斑玄武岩(MORB型玄武岩).斜长角闪岩的锆石SHRIMP法喷发成岩年龄为(1 462±28) Ma,表明其可能代表该区消失了的古洋壳岩石,是四堡期洋壳蛇绿岩的组成部分.     

锦屏一级水电站煌斑岩脉化学复合灌浆试验研究

雅砻江锦屏一级水电站左岸抗力体发育有f2、f5、f8、f42-9断层、煌斑岩脉及深部裂缝等软弱带,需采用相应的工程方法对这些部位进行加固处理。化学复合灌浆是在水泥灌浆基础上发展起来的一种基础处理方法,从化学浆材的选择、灌浆参数的确定、灌浆施工工艺等方面介绍了化学复合灌浆在左岸抗力体煌斑岩脉加固处理中的试验情况。根据试验结果对试验区煌斑岩脉的可灌性进行了分析,并通过岩心观察、岩体透水率、岩体声波和孔内变形模量等资料的对比分析对灌浆效果进行了检测评价,评价表明化学复合灌浆对煌斑岩脉的加固处理效果明显。最后根据本次灌浆的试验结果提出了建议。     

柴达木地块南缘昆北单元变质新元古代花岗岩锆石SHRIMPU-Pb年龄

侵入于香日德南昆北单元金水口岩群白沙河岩组中的变质花岗岩的锆石SFIRIMPu—Pb年龄约为904Ma。该年龄与东昆仑地区已有的定年数据一道,表明柴达木地块南缘存在一条中—新元古代的花岗岩深成侵入岩带,整个柴达木地块可能曾响应了全球Rodinia超大陆汇聚事件。     

http://www.sciencedirect.com/science/article/pii/S1674987110000137

<正>This study attempts to acquire information on tectonic activity in western China from land surface temperature(LST) field data.On the basis of the established relationship between heat and strain,we analyzed the LST distribution in western China using the satellite data product MODIS/Terra.Our results show that:1. There are departures from annual changes of LST in some areas,and that these changes are associated with the activity of some active tectonic zones.2.When annual-change background values caused by climate factors are removed,the long-period component(LST_(LOW)) of temperature residual(△T) of the LST is able to serve as an indicator for tectonic activity.We have found that a major earthquake can produce different effects on the LST fields of surrounding areas.These effects are characterized by both rises and drops in temperature.For example, there was a noteworthy temperature decline associated with the Sumatran M9 earthquake of 2004 in the Bayan Har-Songpan block of central Tibetan Plateau.3.On the other hand,the LST field of a single area may respond differently to major shocks occurring in different areas in the regions surrounding China.For instance,the Kunlun M 8.1 event made the LST on the Longmen Mountains fault zone increase,whereas the Zaisan Lake M 7.9 quake of 2003,and the Sumatran M9 event of 2004.caused decreases in the same area's LST.4.The variations of land surface temperature(LST) over time are different in different tectonic areas.These phenomena may provide clues for the study of tectonic deformation processes.On the basis of these phenomena,we use a combination of temperature data obtained at varied depths,regional seismicity and strain results obtained with GPS measurements,to test the information related to tectonic activity derived from variations of the LST field,and discuss its implications to the creation of models of regional tectonic deformation.