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1.
冀东晚古生代东湾子岩体的岩石成因研究 总被引：5，自引：3，他引：2
冀东晚古生代东湾子岩体由角闪石岩、少量辉石岩和辉长岩组成.典型的堆晶结构、全岩和镁铁质矿物(透辉石、角闪石)的上凸型稀土分布模式、相容元素含量低且变化范围大(如:角闪石岩中V=296×10-6～673×10-6)的特征表明了岩体的堆晶成因.计算得到的与辉石岩中的透辉石相平衡的熔体具有很高的稀土含量,轻重稀土分馏较为明显,富集大离子亲石元素(如:Sr,Ba,K),亏损高场强元素(如:Nh,Zr,Ti),具有典型的弧岩浆特征.透辉石和角闪石的矿物成分也具有弧岩浆的特征.高钙透辉石、大量的角闪石与黑云母的存在说明母岩浆富水.透辉石在高PH2O的状态下与熔体反应,生成角闪石的结构特征也证明了这一点.结合岩体的球化学特征,认为岩浆来源于富集的含有角闪石的尖晶石橄榄岩的部分熔融,母岩浆具有富水的特征(>3%).考虑到岩体形成时代(～300Ma;Zhao et al.,2007)和地质背景,认为东湾子岩体与位于华北北缘的其它晚石炭-早二叠世的岩体形成于同一构造背景下,都是晚古生代时期古亚洲洋向华北板块之下俯冲的产物. 相似文献
2.
博格达山东段苏吉山辉长岩LA-ICP-MS锆石U-Pb年龄、地质地球化学特征及构造意义 总被引：2，自引：0，他引：2
苏吉山辉长岩体位于博格达碰撞造山带东段,卡拉麦里蛇绿混杂岩带西南侧,出露面积约1.8 km~2,岩性为石英角闪辉长岩。苏吉山辉长岩体富含普通角闪石(20%)和磁铁矿物,表明原生岩浆富水、高氧逸度特征,岩石化学组成属于拉斑玄武岩系列,岩石弱富集大离子亲石元素Cs、Rb、Ba、Th、U,显著亏损Nb、Ta、Zr、Hf和弱亏损Ti,显示源区为受俯冲流体交代改造的岩石圈地幔,应是洋壳俯冲的产物。苏吉山辉长岩体锆石U-Pb年龄为308.1±3.3Ma,早于卡拉麦里混杂岩带内碱性花岗岩侵位,介于博格达裂谷活动期,是裂谷作用由全面伸展向局限伸展转换的标志。苏吉山辉长岩空间上位于古亚洲洋板块沿卡拉麦里蛇绿混杂岩带向准噶尔板块斜向俯冲的前进方向,时间上介于博格达裂谷活动期,地球化学上显示洋壳俯冲的特征,各种事实表明,古亚洲洋沿卡拉麦里碰撞带向准噶尔板块斜向俯冲作用形成撕裂型博格达裂谷,博格达裂谷由伸展机制向伸展-碰撞过渡机制的应力调整导致了苏吉山辉长岩体的侵位。 相似文献
3.
红柳沟铜镍矿化基性-超基性岩体位于塔里木板块北缘北山裂谷带,岩体两侧分别为大山头—岗流脑子、方山口—庙庙井—双鹰山2条区域性深大断裂带。岩体侵位于敦煌岩群,铜镍矿化通常赋存于杂岩体中二辉橄榄岩、橄榄二辉辉长岩、橄榄苏长辉长岩等基性程度较高的岩石内。通过SHRIMP锆石U-Pb定年,首次获得红柳沟矿化橄榄角闪辉长苏长岩锆石的U-Pb年龄为(396.7±3.8)Ma,表明该含矿杂岩体的侵位及矿化作用均发生于中泥盆世,结合区内已知黑山和怪石山等铜镍含矿岩体年龄,从而揭示出甘肃北山地区在中—晚泥盆世一直处于陆缘裂谷拉张环境。 相似文献
4.
新疆巴里坤县苏吉山花岗岩体在构造上位于博格达造山带东段,岩性为铁浅闪石碱长花岗岩。全岩具有较高的
SiO2、K2O+Na2O、NK/A和较低的A/CNK含量;轻稀土相对富集、铕弱亏损;不同程度的富集大离子亲石元素和高场强元
素,亏损Cs、Sr、P、Ti;HFSE元素组合（Zr+Nb+Ce+Y） 介于451×10-6~674×10-6,锆石饱和温度范围841~883℃;以上特
征都表现为典型的A型花岗岩特征,判别图解进一步显示其为A2型花岗岩。造岩矿物角闪石属钙质普通角闪石,铁浅闪石
亚类,主量成分Al2O3介于2.9%~4.5%,Si/(Si+Ti+A1)为0.88~0.93,显示出壳源角闪石的特征。LA-ICP-MS 锆石U-Pb 年
龄为301.5±2.4 Ma,表明其形成时代为晚石炭世格舍尔阶。苏吉山A型花岗岩壳源角闪石特征指示其不同于A1亚型与地幔
热柱、裂谷有关的伸展机制,裂谷中晚期侵位表明其不同于A2亚型所代表的后造山环境。结合邻区花岗岩侵位时空特征,
苏吉山A型花岗岩应标志着一种裂谷作用减弱的局限伸展环境,也表明博格达裂谷作用受控于古亚洲洋沿卡拉麦里蛇绿岩
带的斜向俯冲作用。 相似文献
5.
内蒙古自治区西部阿拉善右旗吊井子一带发育有3处镁铁质—超镁铁质岩体,位于华北板块之巴丹吉林坳陷西缘,其主要岩石类型为角闪石岩及橄榄岩。相对比与北大山镁铁质—超镁铁质岩体,本文研究区内角闪石岩分异明显,具有低钾、高钛、高铝、低磷等特征;大离子亲石元素富集,高场强元素亏损,稀土元素分异不明显,La/Sm、La/Ce、La/Yb较低,为亏损地幔来源的(N-MORB)洋中脊玄武岩的特点;橄榄岩富镁贫铁,具有镁质超基性岩的特点,岩浆未发生明显分异,微量元素中Cu、Ni、Co、Cr、V等地幔来源的元素强烈富集,不相容元素富集,稀土元素分异明显,稀土曲线右倾,具有弱Eu异常,La/Sm、La/Ce、La/Yb值较高,岩浆源于富集地幔物质的部分熔融。两种岩石地球化学成分及特征差异较大,不具备同源性特征。 相似文献
6.
位于伊犁微板块北缘阿吾拉勒山那拉提地区的石英二长岩侵位于上石炭统伊什基里克组,LA-ICPMS锆石U-Pb加权平均年龄为307.0±2.5 Ma,时代归属于晚石炭世,代表了岩浆的侵位年龄。岩石地球化学数据显示岩石中Si O_2、Al_2O_3、碱含量较高,里特曼指数σ为3.09~3.94,A/CNK=0.75~0.91,属准铝质钙碱性—碱性花岗岩系列;稀土元素总量(ΣREE)较高,稀土配分模式呈轻稀土富集的右倾型[(La/Yb)_N=2.86~6.14],轻稀土分异程度大于重稀土,Eu具有较为明显的负异常(δEu=0.46~1.02,平均为0.69);强烈富集大离子亲石元素(LILE)Rb、Th、K,亏损高场强元素(HFSE)Nb、Ta、Ti、P;综合表明那拉提石英二长岩具有A_2型花岗岩的特征。高的Th含量(8.68×10~(-6)~14.62×10~(-6))及低的Nb/Ta值(12.23~29.90,均值为18.13)指示岩浆源区主要为地壳,但受到了地幔混染作用的影响。在Nb—Y—Ce、Y/Nb—Ce/Nb及Rb—(Nb+Y)等构造判别图解中样品大多数落入造山后或晚造山花岗岩区,故笔者等认为该岩体应为造山向造山后或晚造山转换时期的产物,属造山后或晚造山岩浆作用。结合区域地质背景,本文认为伊犁微板块在307.0±2.5 Ma前已与准噶尔微板块碰合,北天山洋盆闭合时限早于晚石炭世。这些新资料为西天山区域大地构造演化研究提供了新的约束。 相似文献
7.
中国东南部福州花岗质杂岩的岩石学和地球化学 总被引：3，自引：2，他引：3
中国东南部福州复式岩体主要由两个岩套构成:(1)钙碱性岩套(丹阳岩体、福州岩体)侵位于约105—100Ma前(Rb-Sr年龄)。这些花岗岩显示了有斜长石和角闪石分离的分异作用。Sr和Nd同位素证据说明老地壳物质在岩浆形成中起了重要作用。(2)碱性岩套(魁岐岩体、笔架山岩体)侵位于90Ma前。这个岩套主要由超溶线过碱性花岗岩组成。这些过碱性花岗岩的岩浆分异作用很微弱,特征是稀土含量高。Sr和Nd同位素资料表明,在岩浆形成过程中地壳物质带入未起重要作用。 由岩石成因研究可见,福州复式岩体是逐渐连续侵位于地壳上部。钙碱性岩套是侵位于俯冲带的典型岩套,而碱性岩套则与较大的地壳深断裂有关。 相似文献
8.
祁连山扎麻什基性杂岩体岩石地球化学特征及其大地构造意义 总被引：4，自引：7，他引：4
青海省祁连县扎麻什基性杂岩体侵位于寒武一奥陶纪地层中。岩体以辉长岩为主，并伴有超基性岩，辉石岩，角闪石岩与闪长岩出露。岩石地球化学研究表明，该岩体是由钙碱性岩浆经不同程度的分离结晶作用形成的。岩石具富集大离子亲石元素(LILE)而亏损高场强元素(HFSE)，并具有明显Nb和Ta负异常。结合该岩体与北侧清水沟一百经寺俯冲杂岩的空间分布关系，表明该杂岩体是形成于北祁连洋壳向南俯冲形成的岛弧环境。 相似文献
9.
大通沟南山地区基性-超基性岩体位于柴达木地块西北缘,侵位于新元古代地层。岩体多呈北东向展布,脉状、透镜状产出,岩石类型主要为橄榄辉石岩、辉石角闪石岩、辉石橄榄岩、橄榄二辉岩等,铜镍矿化主要赋存于橄榄辉石岩、辉石角闪石岩中。岩石表现出低硅、中镁、高钛、高钙等特征,富集轻稀土元素和大离子亲石元素(Th、U、Rb),相对亏损高场强元素(Nb、Ta、Ti)。岩石学及岩石地球化学研究表明岩浆在演化过程中发生了一定程度的结晶分异和同化混染,显示出良好的铜镍矿成矿条件。岩石MgO含量、m/f值等指标显示岩体具有良好的铜镍矿含矿性。通过对岩体形成环境、岩石地球化学、物化探特征综合研究,表明大通沟南山地区基性-超基性岩具有良好的铜镍硫化物矿床形成条件和找矿前景。 相似文献
10.
《西北地质》2016,(1)
甘肃北山大山头—黑山一带位于塔里木板块北缘北山裂谷带,区内与基性-超基性岩有关的铜镍矿化较为普遍,含矿岩体多受庙庙井-西双鹰山及其次级断裂控制,成岩时代集中在358~397Ma,岩体的形成和演化与裂谷作用密切相关。区内与铜镍矿化有关的基性-超基性岩体规模较小,多期侵位且分异较好,具高Mg、低碱、低Ca和低Ti的特征,含矿岩相具有较高的Mg~#,稀土元素配分形式较为平坦,LREE略富集,大离子亲石元素(Rb、Ba、Sr、U)相对富集,高场强元素(Nb、Zr、Hf)相对亏损。矿化岩体发育强度不高,但规模较大的Cu、Ni成矿元素异常,并有套合较好的磁、电异常。通过对区内已知及新发现的几处铜镍矿化基性-超基性岩体地质特征、岩石学特征及岩石地球化学特征等进行研究,结合近年来的地质找矿实践,认为该地区与铁质基性-超基性岩有关的铜镍成矿条件较好,具有进一步寻找岩浆型铜镍硫化物矿床的前景。 相似文献
11.
摩擦桩基桩土间极限摩阻力取值问题探讨 总被引：1，自引：0，他引：1
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。 相似文献
12.
位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。 相似文献
13.
某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
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。 相似文献
14.
The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
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. 相似文献
15.
混凝剂处理钻井废泥浆液的研究 总被引：4，自引：0，他引：4
通过烧杯搅拌实验对混凝剂处理钻井废泥浆液进行研究,从混凝剂适应p H值范围、混凝效果、沉降速度三方面研究比较,找出一种较为理想的混凝剂,并分析了影响混凝剂性能的主要因素,确定了混凝剂的最佳投放剂量。 相似文献
16.
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 相似文献
17.
黄河源区水环境变化及黄河出现冬季断流的原因 总被引：12，自引：0，他引：12
自1954年有水文观测资料以来，黄河曾在青海省玛多县黄河沿水文站发生过3次断流。本文在分析黄河源区水环境特征及其影响因素的基础上指出，鄂陵湖、扎陵湖的环湖融区调节能力低，当遇到连续干旱、冬季其调节水量不足以维系黄河径流时便会发生断流，这是断流的主因。湖水位降低、开采沙金、过度放牧等自然和人为因素也会对黄河发生断流产生影响。鄂陵湖口附近黄河上修建的水电站开始蓄水，提高了两湖及环湖融区的调节能力，今后黄河冬季出现断流的可能性将大为降低。 相似文献
18.
利用天山南坡科其喀尔冰川3号观测站2009年全年的气象观测资料,分析研究了科其喀尔冰川表碛区的小气候特征. 结果表明：总辐射和净辐射夏秋季较高、冬春季较低;反射辐射和地表反照率反之. 与其他地区不同,该区主要受积雪物理性质和下垫面状况的影响,冬春季地表反照率日变化表现为由大到小的变化过程,夏秋季表现为倒U型. 温度年变化表现为夏秋季高、冬春季低,最高月均值出现在8月,为9.4℃,最低月均值出现在1月,为-9.6℃. 受山谷风和冰川风的影响,全年的风向以西北风和西北偏西风为主,风向的日变化以11：00为界发生转向. 受降水和冰川消融等的影响,比湿夏秋季月均值较大,冬春季月均值较小. 相似文献
19.
Guboglo M. N. 《GeoJournal》1980,4(1):53-58
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. 相似文献
20.
Climate: Is the past the key to the future? 总被引：2，自引：0，他引：2
The climate of the Holocene is not well suited to be the baseline for the climate of the planet. It is an interglacial, a
state typical of only 10% of the past few million years. It is a time of relative sea-level stability after a rapid 130-m
rise from the lowstand during the last glacial maximum. Physical geologic processes are operating at unusual rates and much
of the geochemical system is not in a steady state. During most of the Phanerozoic there have been no continental ice sheets
on the earth, and the planet’s meridional temperature gradient has been much less than it is presently. Major factors influencing
climate are insolation, greenhouse gases, paleogeography, and vegetation; the first two are discussed in this paper. Changes
in the earth’s orbital parameters affect the amount of radiation received from the sun at different latitudes over the course
of the year. During the last climate cycle, the waxing and waning of the northern hemisphere continental ice sheets closely
followed the changes in summer insolation at the latitude of the northern hemisphere polar circle. The overall intensity of
insolation in the northern hemisphere is governed by the precession of the earth’s axis of rotation, and the precession and
ellipticity of the earth’s orbit. At the polar circle a meridional minimum of summer insolation becomes alternately more and
less pronounced as the obliquity of the earth’s axis of rotation changes. Feedback processes amplify the insolation signal.
Greenhouse gases (H2O, CO2, CH4, CFCs) modulate the insolation-driven climate. The atmospheric content of CO2 during the last glacial maximum was approximately 30% less than during the present interglacial. A variety of possible causes
for this change have been postulated. The present burning of fossil fuels, deforestation, and cement manufacture since the
beginning of the industrial revolution have added CO2 to the atmosphere when its content due to glacial-interglacial variation was already at a maximum. Anthropogenic activity
has increased the CO2 content of the atmosphere to 130% of its previous Holocene level, probably higher than at any time during the past few million
years. During the Late Cretaceous the atmospheric CO2 content was probably about four times that of the present, the level to which it may rise at the end of the next century.
The results of a Campanian (80 Ma) climate simulation suggest that the positive feedback between CO2 and another important greenhouse gas, H2O, raised the earth’s temperature to a level where latent heat transport became much more significant than it is presently,
and operated efficiently at all latitudes. Atmospheric high- and low-pressure systems were as much the result of variations
in the vapor content of the air as of temperature differences. In our present state of knowledge, future climate change is
unpredictable because by adding CO2 to the atmosphere we are forcing the climate toward a “greenhouse” mode when it is accustomed to moving between the glacial–interglacial
“icehouse” states that reflect the waxing and waning of ice sheets. At the same time we are replacing freely transpiring C3
plants with water-conserving C4 plants, producing a global vegetation complex that has no past analog. The past climates of
the earth cannot be used as a direct guide to what may occur in the future. To understand what may happen in the future we
must learn about the first principles of physics and chemistry related to the earth’s system. The fundamental mechanisms of
the climate system are best explored in simulations of the earth’s ancient extreme climates.
Received: 7 November 1996/Accepted: 23 January 1997 相似文献