中国大陆科学钻探100-2000m超高压变质岩普通Pb同位素地球化学初步研究——俯冲陆壳内脱耦的证据   总被引：1，自引：0，他引：1  

董锋李曙光  李秋立刘贻灿 陈福坤 《岩石学报》2006,22(7):1791-1798

本文首次对中国大陆科学钻探工程100～2000m榴辉岩中的绿辉石和片麻岩中的长石进行了普通Pb同位素研究。钻孔上部岩段（0-800m）样品放射成因Pb同位素含量比较高且变化幅度较小（^206Pb／^204Pb=16．81-17．29，^207Pb／^204Pb=15．37-15．45，^208Pb／^204Pb=37．20-37．66），说明其原岩的U／Pb和Th／Pb或者初始Pb同位素比值比较高。钻孔中部岩段（800-1600m）发育有韧性剪切带，相应的Pb同位素比值开始降低且有起伏（^206Pb／^204Pb=16．26-16．72，^207Pb／^204Pb=15．27～15．38，^208Pb／^204Pb=36．73～37．40）、钻孔下部岩段（800～1600m）样品放射成因Ph同位素含量低但变化幅度较小（^206Pb／^204Pb=16.05～16．46，^207Pb／^204Pb：15．22～15.29，^208Pb／^204Pb=36．68～37．48），说明其原岩的U／Pb和Th／Pb或者初始Ph同位素比值比较低。实测数据同模拟数据对比表明，钻孔上、下两岩段样品普通Ph同位素不同一方面是由于继承了原岩初始Pb同位素不同，另一方面是由它们的μ值不同所致。结合氧同位素研究，本文认为800m以上和1600m以下分属上地壳和中地壳．前者是从俯冲大陆岩石圈解耦的上地壳，在大陆岩石圈俯冲过程中，上部岩片同俯冲的大陆岩石圈发生挤离，率先沿着这一个挤离面逆冲折返至浅部。下岩片是随后从俯冲岩石圈解耦的中地壳岩片，并折返至浅部下伏在先期折返的上部岩片之下。考虑到中部岩段（800～1600m）既发育有韧性剪切带又具有异常低^18O峰值（Xiao et al．，2006），挤离面是在地壳内部晚元古代的断裂带及冷水活动通道基础上发育起来的。  相似文献   

中国大陆科学钻探（CCSD）主孔100-2000m区间磁化率的变异特征及其地质意义     

杨涛  刘庆生  吴耀  金振民  潘和平  牛一雄 《岩石学报》2006,22(7):2089-2094

对中国大陆科学钻探主孔100—2000m区间岩心样品磁化率与钻孔原位测井磁化率进行系统时比研究。结果表明,控制岩石磁化率的主要因素是岩性和退变质作用,其中蛇纹石化石榴石橄榄岩的磁化率最大,样品平均磁化率为86．277×10-3SI,正片麻岩,退变质榴辉岩,榴辉岩,副片麻岩次之,角闪岩的磁化率最小,样品平均磁化率为1．698×10-3SI。不同退变质程度榴辉岩的磁化率特征具有明显的差异:中-强程度退变质榴辉岩由于退变质过程所产生的磁铁矿和钛铁矿-钛磁铁矿,其磁化率最大;随着退变质作用的进一步加剧,这些磁铁矿和钛铁矿-钛磁铁矿被完全分解,导致完全退变质榴辉岩的磁化率最小;新鲜榴辉岩的磁化率介于两者之间。在该深度区间,约70％岩心样品磁化率与测井磁化率的比值小于4．0,其中以<2．0为主,相同岩性岩石(如榴辉岩,退变质榴辉岩和副片麻岩)磁化率的比值随深度变化较小。岩心样品磁化率和测井磁化率之间的欧氏距离位于3．0-6．4范围,且随深度变化不明显,如在100～600m和1500～2000m两个深度范围的欧氏距离分别为3．0-5．2和3．2～5．3,表现出相似的变化特征,显示了在此区间深度范围内,地层压力对磁化率的基本没有影响。  相似文献   

大陆科学钻探与中国第一口科学钻选址   总被引：2，自引：0，他引：2  

张永康 《江苏地质》1998,22(4):193-198

大陆科学钻探是一项堪与航天技术媲美的浩大系统工程。它的实施具有深远的科学和经济意义。通过介绍国外大陆科学钻探的现状和成果,阐述大陆科学钻探对地球基础科学、其他自然科学研究所具有的重大促进作用,从而为开展我国第一口大陆科学钻探,缩短与国外先进水平的差距提供有益的借鉴。  相似文献   

VERIFICATION TEST OF THE PHYSICAL MODEL IN WUHAN FOR THE GEZHOUBA DAM REGION WITH RESPECT TO ITS FIRST STAGE CONSTRUCTION IN OPERATION ── A SUMMARY REPORT     

Lin Wanquan  Wang Mingna 《国际泥沙研究》1989,(1)

I. INTRODUCTIONThe Gezhouba Project is located on the main stem of the Yangtze River with a total installed capacity of 2750 MW. The general layout of the project is shown in Fig. l--a. The drainage area upstream of the project is 1 million sq. km with an…  相似文献   

Damage to Rocks and Cementitious Materials from Solid Impact     

A. W. Momber 《Rock Mechanics and Rock Engineering》2004,37(1):57-82

Summary The erosion of four rock types and two cementitious materials by solid particle impact is investigated. The experimental set-up used to perform the erosion tests is briefly described. The materials are eroded predominantly by intergranular and intercrystalline fracture. For the cementitious materials, the interface between cement matrix and aggregate is of decisive importance. The power exponents for the particle velocity are estimated and found to vary between 2.59 and 3.65. A statistical fracture model is derived to discuss deviations in the particle velocity power exponent. It is further shown that the experimental results of this study confirm the erosion model of Finnie and Oh (1966); an exception is schist which shows features of plastic deformation and radial cracking during the Hertzian indentation test.  相似文献   

中国大陆科学钻探工程主孔及周边地区花岗质片麻岩的地球化学性质和超高压变质作用标志的识别   总被引：36，自引：34，他引：36  

刘福来许志琴  杨经绥张泽明薛怀民  李天福 《岩石学报》2004,20(1):9-26

花岗质片麻岩是中国大陆科学钻探工程主孔0-2000m深度范围内出露的主要岩石类型之一,集中分布于1113.14-1596.22m之间,而在0-1113.14m和1596.22-2000m深度范围内主要以“夹层”形式赋存于副片麻岩和(退变)榴辉岩中,夹层的厚度为0.54-5.82m左右。花岗质片麻岩累计厚度430.98m,占2000m岩心的21.55％左右。地球化学研究结果表明,主孔中花岗质片麻岩SiO2含量普遍偏高,为71.55％-77.18％之间,Al2O3含量为11.54％-13.57％。TiO2、Fe2O3、FeO、MnO和MgO含量则明显偏低,其中Fe2O3 FeO总量为1.05％-2.94％,MgO=0.06％-0.59％。CaO含量为0.30％-2.65％。Na2O和K2O含量变化相对较大,分别为0.29％-4.06％和2.90％-6.67％之间,且大多数样品K2O含量高于Na2O含量。稀土元素配分模式具有右倾式的特点,轻稀土相对富集,而重稀土相对亏损,具有强烈的负Eu异常,Eu/Eu=0.21-0.26之间。在标准化蛛网图上,则显示Ta、Nb、P和Ti的明显亏损以及中等-强烈的负Ba异常,Ba/Ba=0.25-O.64之间,平均值为0.45左右。上述主元素、稀土元素和微量元素特征与中国大陆科学钻探预先导孔CCSD-PP1岩心以及东海及其邻区地表露头的花岗质片麻岩的化学成分十分相似,具有A型花岗岩的地球化学特征。采用激光拉曼技术,配备阴极发光测试,确认中国大陆科学钻  相似文献   

Middle Miocene to Pleistocene radiolarian biostratigraphy in the Northwest Pacific Ocean, ODP Leg 186   总被引：2，自引：0，他引：2  

Shin-ichi Kamikuri  Hiroshi Nishi  Isao Motoyama  Saneatsu Saito 《Island Arc》2004,13(1):191-226

Abstract The Upper Cenozoic sedimentary sequences drilled at Sites 1150 and 1151, Ocean Drilling Program Leg 186, enabled establishment of radiolarian zonation and calibration of the age of bioevents in the forearc area of the northern Japan Islands. The sequences were divided into nine zones from the Pleistocene Botryostrobus aquilonaris Zone to the Upper Miocene Lipmanella redondoensis Zone at Site 1150, and 11 zones from the Pleistocene Stylatractus universus Zone to the Middle Miocene Dendrospyris? sakaii Zone at Site 1151. These zones correlate successfully with the studied sequences of many of deep‐sea cores in the Northwest Pacific Ocean and with some sections of onshore Japan. Of 67 important radiolarian bioevents recognized during the study, 29 Pleistocene to Upper Miocene events were directly tied to the geomagnetic polarity time scale through the well‐defined paleomagnetic polarity records, and 21 Upper Miocene events were calibrated based on the diatom biostratigraphy. Of these events, 24 geographically widespread events were selected to test synchroneity and usefulness as time‐horizons within the mid‐to‐high latitude of the Northwest Pacific, involving eight other offshore and onshore sections. Examination showed that most of the zonal boundary events are synchronous within the considered region, and that many diachronous events, most of which are eliminated from the zonal scheme, are unreliable events linked to rare and sporadic occurrences of the species. Radiolarian biostratigraphy of the studied cores clearly indicates three major hiatuses in the Middle Pleistocene, Late Miocene and late Middle Miocene. The latter two hiatuses can be correlated to two global oceanic hiatuses, NH6 and NH3, respectively.  相似文献   

RATIONAL BASIS FOR SUSPENDED SEDIMENT MODELING   总被引：1，自引：0，他引：1  

Jianjun ZHOU  Biniiang LIN  Bingnan LIN Prof  Dept. of Hydraulic Eng.  Tsinghua University  Beijing  P.R. China  Senior Lecturer  School of Eng.  Cardiff University  Queen''''s Buildings  P.O.Box  Cardiff  CF EW  UK  Dir. Emeritus  China Inst. of Water Resources  Hydropower Res.  Formerly  Chief of Sedimentation Panel for TGP  Chairman Emeritus of Advising Council  IRTCES  P.O. Box.  Beijing  P.R. China   《国际泥沙研究》2003,18(3)

This paper presents a rational basis to model the transport of suspended sediment. The loose-boundary condition for 3D models and the adjustment coefficients for both the depth-integrated 2D and laterally integrated 1D models are treated comprehensively. A combination of Dirichlet and Neumann conditions is proposed as the loose-boundary condition. The adjustment coefficient for 2D models is obtained on the basis of the proposed boundary condition and analytical solutions developed for some simple cases of non-equilibrium transport of sediment in uniform flows. The adjustment coefficient for 1D models for natural rivers is further obtained from lateral integration. Comparisons with analytical solutions and a considerable amount of laboratory and prototype data show that mathematical models developed along the proposed line of attack would well simulate the transport of suspended sediment in practical problems.  相似文献   

江苏东海芝麻房预先导孔（CCSD-PPl）橄榄岩及其反映的上地幔亏损和交代事件   总被引：10，自引：2，他引：10  

李天福杨经绥  张儒媛 《地质学报》2003,77(4):492-509

芝麻房预先导孔橄榄岩岩石类型有二辉橄榄岩、方辉橄榄岩、单辉橄榄岩和纯橄榄岩，其中前3种多数含有石榴子石。这些岩石在垂向上显示成层性，没有某种方向的韵律变化，它们之间呈渐变过渡关系。对样品进行主量元素、微量元素、稀土元素和Sr、Nd、O同位素分析表明，随着样品MgO含量的增高，Al2O3、CaO逐渐降低，呈良好的相关关系，并且大致上从石榴橄榄岩类到不含石榴子石的橄榄岩类主量元素的亏损程度增高，两者一般均比原始地幔主量元素亏损。稀土元素配分型式表现为右倾的轻稀土富集型，在微量元素蛛网图上，也表现为强不相容元素和微量元素到适度不相容元素的总体右倾型，与原始地幔相比，均富集强不相容元素。富集程度的不同与主量元素的亏损无对应关系，说明主量元素和微量元素各自的特点不是同一种事件造成的，而是先前地幔部分熔融作用之后又发生了富含不相容元素流体的交代作用。Sr、Nd同位素具有富集特点，变化范围较大，而且主量元素较亏损的岩石更富集Sr同位素，显示了交代富集的特点。稀土元素(Ce／Yb)x比值和εNd之间的负相关关系和Rb丰度与Sr同位素之间的正相关关系表明，富集Sr、Nd同位素的流体和富集不相容微量元素的流体均来自地幔。  相似文献   

煤层气井钻井液特点的探讨   总被引：4，自引：0，他引：4  

孙建平 《中国煤田地质》2003,15(4):61-62,71

煤层气参数井一般要求采用清水钻取煤心，生产井则主要采用无粘土钻井液、优质钻井液或清水施工。应用清水或无粘土钻井液钻井时，孔内产生的岩屑或岩粉进入煤储层后，会堵塞煤层裂隙或孔隙，降低煤层气产能。而应用优质钻井液钻进时，由于泥皮的过滤作用，能更好地保护煤层不受伤害，同时能降低钻井施工风险，确保井内安全。  相似文献