扬子西缘江浪穹窿核部里伍岩群的形成时代及构造背景

江浪穹窿位于扬子陆块西缘,核部地层里伍岩群为一套变质的火山-沉积岩系。为精确厘定里伍岩群的形成时代并探讨其成岩构造背景,本文进行了LA-ICP-MS锆石U-Pb年代学以及岩石地球化学研究。定年结果表明变沉积岩中碎屑锆石年龄介于2521~262 Ma,其中最年轻一组岩浆成因锆石的~(206)Pb/~(238)U加权平均年龄为552.8±5.7 Ma(MSWD=2.1,n=6)。变沉积岩SiO_2含量变化很大(53.48%~96.08%),显示明显的Eu负异常(Eu/Eu*=0.50~0.67),相对富集大离子亲石元素(Rb、Ba和U等)、亏损高场强元素(Nb、Ta、Zr、Hf和Ti等),其稀土、微量配分模式与大陆上地壳完全一致。变基性火山岩具有很低的SiO_2含量(39.92%~48.27%),其稀土、微量配分模式平坦,类似于E-MORB。结合变基性火山岩的锆石U-Pb定年结果(542±9.0 Ma),本文指出里伍岩群应当形成于新元古代晚期(553~542 Ma),而并非前人所认为的古元古代或中元古代。变沉积岩的物源区主要为扬子西缘新元古代地质体,与变基性火山岩均形成于Gondwana超大陆聚合之后的板片俯冲环境。此外,碎屑锆石的年龄谱反映江浪穹窿可能存在太古宙—古元古代变质基底,并且具有Rodinia超大陆的会聚-裂解事件以及加里东运动的地质年龄记录。     

内蒙古白乃庙铜-金-钼矿床侵入岩和围岩成因:岩石地球化学和Hf同位素的证据

白乃庙铜-金-钼矿是华北北缘中段的一个重要矿床,矿体主要赋存在早古生代白乃庙群绿片岩中,其成矿与花岗闪长斑岩密切相关。岩石地球化学特征显示,该区侵入岩花岗闪长斑岩以及石英闪长岩与起源于俯冲洋壳的埃达克岩的特征类似,岩浆在上升侵位过程中受到了明显的变质基底的混染作用。赋矿围岩绿片岩的原岩主要为中基性火山岩,锆石Hf同位素数据显示,白乃庙绿片岩、变质安山岩中锆石的εHf(t)变化范围为-4.64~+11.29之间,而白音都西群变质石英砂岩的εHf(t)为-4.30~+15.50,显示白乃庙地区围岩原岩源区物质主要来源于亏损地幔,并在侵位过程中受到了古老地壳基底的混染作用。2类岩石的二阶段Hf同位素模式年龄分别为693~2843 Ma和481~2363 Ma,峰值区间在700~1500 Ma,揭示了华北板块中-新元古代陆壳增生和构造热事件。矿床地质特征、岩石学和地球化学组成表明,白乃庙铜-金-钼矿床具有低氧逸度的特征,可能为还原性斑岩型矿床。     

新疆东准噶尔塔克尔巴斯陶一带闪长岩岩石学及地球化学特征

塔克尔巴斯陶闪长岩体位于东准噶尔北缘,乌伦古河断裂南侧,卡拉麦里断裂北侧。该岩体由辉长闪长岩、辉石闪长岩、二长闪长岩组成,SHIRMP锆石U-Pb测年为(362.5±9.4)Ma。岩石属高钾钙碱系列,富集大离子亲石元素Sr,K,Ba,亏损高场强元素Nb,Ta,Ti,Th,其中Ta为0.28×10-6~0.73×10-6,Hf/Ta为7.41~12.86,Hf/Th为0.67~1.44,Zr/Nb为15.25~29.85,且大多数样品的Nb,Ta有较强的亏损等特征,反映岩浆源区可能来自地幔,并与有着明显Nb,Ta亏损的岛弧环境闪长岩相似。岩体高Sr低Y及低Sr/Y值,同时δEu=0.75~1.09,(La/Yb)N=6.04~11.67,暗示岩体中有大陆地壳物质参与。通过获得的SHIRMP锆石U-Pb年龄及岩石地球化学等特征,判断塔克尔巴斯陶岩体产于俯冲岛弧环境,岩体为地幔岩浆来源,并有一定地壳物质参与,同时也约束了东准噶尔地区俯冲-消减作用结束的时限。     

新疆阿尔泰南缘达拉乌兹双峰式火山岩年龄及岩石成因

阿尔泰南缘达拉乌兹一带出露了一套玄武岩和流纹岩频繁互层的双峰式火山岩组合。该套双峰式火山岩发生了绿片岩相变质作用,其基性端元——变质玄武岩和酸性端元——变质流纹岩具明显的变余斑状结构。利用LA-ICP-MS锆石U-Pb法获得流纹岩的喷发年龄365.6±1.6Ma和捕获的锆石年龄413.5±2.0Ma。变质玄武岩富TiO2、碱(富钠)(Na2O/K2O=4.43～19.33)和FeOT,贫MgO和CaO,轻微富集LILE和LREE,具弱的Nb、Ta和Ti的负异常,具有高于正常弧火山岩但低于OIB的HFSE元素(Nb、Ta、Zr、Hf)的含量,Eu负异常不明显。流纹岩具有高SiO2和全碱,具有低的TiO2、极低的MgO和FeOT,呈现明显的Ti、P、Sr、Ba负异常,Th、U、Pb的正异常,HFSE元素(Zr、Hf)和LREE略富集但Nb、Ta亏损的特征,并显示Eu的明显负异常(δEu=0.21～0.41)。它们均具有相似于N-MORB的较低的Pb同位素组成。玄武岩与流纹岩来自两个不同的岩浆房,玄武岩为受俯冲物质加入的亏损软流圈地幔部分熔融后并发生结晶分异作用的结果,流纹岩为新生的地壳物质受幔源岩浆加热熔融并与之混合后演化的产物。结合阿尔泰南缘地区的构造演化特征,推测该双峰式火山岩俯冲作用引起的局部拉张作用的产物。     

内蒙古乌拉特后旗乌兰敖包地区二叠纪中-基性火山岩地球化学、年代学、Hf同位素特征及其地质意义

内蒙古乌拉特后旗乌兰敖包地区中-基性火山岩位于华北陆块北缘西段,野外出露岩性主要为灰黑色-深灰绿色玄武岩、深灰绿色玄武安山岩和灰绿色安山岩等。岩石样品中SiO_2含量49.33~65.84%,Na_2O含量0.53~5.49%,K_2O平均值为0.25~6.40%,属于钙碱性系列;由基性到中性岩石中稀土总量呈增加趋势,轻稀土元素富集程度增加,δEu负异常逐渐明显;微量元素显示火山岩普遍具有不同程度的Ta、Nb亏损,U、Ba、K等大离子亲石元素富集特征,具有俯冲带弧岩浆岩的特征。火山岩中岩浆锆石U-Pb测年结果为285.0±2.3 Ma和265.0±1.5Ma,表明其形成时代为早-中二叠世;火山岩与下伏地层接触关系及捕获锆石的年龄特征指示,乌兰敖包地区火山岩形成在华北陆块北缘之上。锆石Hf同位素信息指示岩浆起源于受俯冲板块影响的亏损地幔,岩浆上升过程中加入了壳源物质。     

新疆吾尔喀什尔地区晚泥盆世铁列克提组火山岩LAICP-MS锆石U-Pb年龄、地球化学特征及构造意义

西准噶尔晚泥盆世铁列克提组主要分布于吾尔喀什尔山西部,为一套海陆交互相火山-沉积地层。火山岩地球化学研究表明,Si O2含量为51.18%~62.48%,Ti O2为0.60%~1.49%、全碱(K2O+Na2O)为1.26%~6.28%,相对富钠贫钾。A12O3为15.53%~18.68%、Mg O为2.64%~7.55%,Mg#为41.2~58.5,属于亚碱性系列。稀土元素总量高(∑REE=36.21×10-6~97.10×10-6),轻、重稀土分馏较强((La/Yb)N=2.88~6.72),具轻微负Eu异常(Eu/Eu*=0.74~1.07)。相对富集LILE(Rb、Ba、Th和K),亏损HFSE(Zr、Hf),Nb和Ta强烈亏损,Ti轻微亏损。岩石源区主要受俯冲流体交代,受地壳物质混染较弱,整体具有弧火山岩的地球化学特征。与火山岩伴生的凝灰岩LA ICP-MS锆石U-Pb同位素测年结果为363.3±4Ma。综合分析认为铁列克提组火山岩属于大陆边缘弧火山作用的产物,同时,博什库尔-成吉斯岩浆弧可能至少延续至晚泥盆世。这为进一步认识西准噶尔博什库尔-成吉斯岩浆弧的性质及构造演化提供了证据。     

四川九龙柏香林铜矿床围岩稀土、微量元素地球化学

通过对柏香林铜矿床变沉积岩和变基性火山岩围岩稀土、微量元素分析显示,二云石英片岩稀土配分型为右倾型,具有较强的Eu负异常(Eu/Eu*=0.43~0.30,平均0.38),富集大离子亲石元素(Rb、Ba和U等),亏损高场强元素(Nb、Ta和Hf),与大陆地壳基本一致;黑云绿泥透闪岩的稀土、微量配分较为平坦,(La/Yb)N平均1.57,无明显Ce(Ce/Ce*平均0.88)与Eu异常(Eu/Eu*平均1.01)。综合分析认为,里伍岩群变沉积岩与变基性火山岩很可能形成于统一的弧后盆地构造背景,弧后盆地岩浆活动在其沉积过程中携带来丰富的金属元素,为江浪穹窿富铜矿床的发育奠定了物质条件。     

漠河盆地东南部中生代火山岩年代学与地球化学研究

漠河盆地东南部中生代火山岩地层主要由光华组和甘河组组成,锆石U--Pb定年结果确定两组火山岩分别形成于128~125 Ma和126~120 Ma。光华组流纹岩高硅富碱、贫钙铁镁;轻重稀土分馏较明显[w(La/Yb)N=13.01~17.99],铕异常中等(δEu=0.49~0.67);富集大离子亲石元素Rb、K、Th、U,亏损高场强元素Nb、Ta、P、Ti;锆石εHf(t)值为-2.5~3.0,两阶段Hf模式年龄为989~1 130 Ma;岩浆源区为中元古代末期的地壳物质。甘河组粗安岩和玄武粗安岩富碱高钾,镁指数较大(Mg#≈48);稀土元素配分曲线为轻稀土富集的右倾型[w(La/Yb)N=12.67~23.21],铕异常不明显(δEu=0.77~0.91);富集Rb、Ba、K、Th、U等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素;锆石εHf(t)值为-1.2~4.1;岩浆源区为俯冲流体交代过的岩石圈地幔,岩浆经历了一定程度分离结晶作用。     

东昆仑马尼特地区片麻状花岗闪长岩锆石U-Pb年代学、地球化学及其构造背景

为确定东昆仑马尼特地区片麻状花岗闪长岩的形成时代、源区性质和构造背景,对其进行了锆石U-Pb年代学、地球化学和锆石Hf同位素研究.本次测试的片麻状花岗闪长岩锆石LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry) U-Pb加权平均年龄为495.6±1.1 Ma(MSWD=0.13),属于晚寒武世.马尼特片麻状花岗闪长岩SiO₂含量为61.47%~63.99%,Na₂O、K₂O和CaO含量分别为2.91%~3.64%、0.93%~2.31%和4.29%~6.52%,全碱ALK=3.92%~5.69%,铝饱和指数A/CNK=0.83~0.97,属准铝质钙碱性系列岩石.岩石具有富集大离子亲石元素(Rb、K)和不相容元素(Th、U),相对亏损Nb、Ta、Zr、Ti高场强元素的特征,Nb/Ta、La/Nb、Th/Nb、Th/La等比值显示出岩石具有壳源特征.岩石具有高的ε_Hf(t)值(12.2~15.0),Hf两阶段模式年龄在506~662 Ma范围内,其岩浆源区初始物质主要来源于新生地壳.岩石在微量元素Rb-(Y+Nb)构造判别图落入火山弧花岗岩区域,在R1-R2构造判别图落入板块碰撞前消减区花岗岩区域.结合岩石成岩年龄、地球化学特征以及区域构造演化,推测其应形成于原特提斯洋俯冲的构造环境,属于大洋洋壳向南俯冲的产物,即柴达木地块和万宝沟大洋玄武岩高原之间的洋壳同时向南、北发生双向俯冲消减.      

北阿尔金构造带红柳沟钾长花岗岩地球化学特征、LA-ICP-MS锆石U-Pb定年和Hf同位素组成

出露于阿尔金构造带北缘红柳沟-拉配泉混杂岩带西段的红柳沟钾长花岗岩, SiO2>69.0%, Al2O3>13.0%,(K2O+Na2O)>7.0%, K2O/Na2O>1, A/CNK介于1.04~1.08之间, 属高钾钙碱性系列的弱过铝质岩石。该岩石富集大离子亲石元素(LILE), 亏损Nb、Ta、Sr、P、Ti等高场强元素(HFSE);∑REE偏低(128.47×10-6~150.67×10-6), Eu负异常中等(δEu=0.59~0.67), LREE相对富集, 轻重稀土元素分馏明显, 其Nb/Ta、Zr/Hf比值接近上地壳, 锆石具有负的εHf(t)值(-7.13~-5.12),两阶段Hf模式年龄(TDM2)变化范围为1786~1912Ma, 反映其源区物质主要来源于古老地壳。源岩判别图解和Al2O3/TiO2<100指示其为中上地壳变质砂屑质沉积岩部分熔融的产物。LA-ICP-MS锆石U-Pb年龄为500.3Ma±1.2Ma, 结合锆石CL图像具有岩浆环带特征和Th/U>0.4, 推断该年龄为花岗岩的形成年龄。综合区域地质背景, 认为该岩石形成于与洋壳俯冲作用有关的陆缘火山弧环境。     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

塘口水电站坝基岩体透水性和渗漏问题分析

塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

Calculation of the Inverse of the Covariance

In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.     

某高速公路下伏煤矿采空区稳定性分析

在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。      

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

Artemia in the Salt Lakes of Russia:the Productivity of Populations,the Reserves of the Cysts and the Fisheries

正Artemia cysts are an extremely important component of aquaculture diets.It is well established that the cultivation of fish and shellfish derive substantial health and growth advantages when Artemia are included in the diets of the