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1.
天山中西段古生代花岗岩TIMS法锆石U-Pb同位素定年及岩石地球化学特征研究 总被引：23，自引：0，他引：23
通过对天山中西段古生代花岗岩的锆石TIMS法U-Pb同位素定年,表明中天山托克逊南—库米什北侵入于奥陶纪可可乃克群中的碱长花岗岩形成时代为395.1±0.9Ma,花岗闪长岩体形成于393.5±2.7Ma,石英闪长岩体形成于327.3±0.9Ma,斜长花岗岩体形成时代为424.1±1.1Ma,并揭示出中天山中段库米什地区的3期构造岩浆事件,分别相当于早志留世、中泥盆世和早石炭世。中天山哈希勒根大坂黑云母花岗岩形成于286.8±0.8Ma。对伊犁石炭—二叠纪裂谷带中花岗侵入岩类的锆石TIMS法U-Pb同位素定年,表明霍城果子沟角闪花岗岩形成于351.9±1.6Ma,昭苏煤矿花岗闪长岩体形成时代为348.4±0.8Ma,新源则克台角闪辉长岩体形成于308.2±1.2Ma。南天山巴音布鲁克地区侵入于巴音布鲁克群中的石英闪长岩体形成时代为446.8±1.2Ma,独—库公路南段库尔干道班14.6km和15.2km处的角闪斜长花岗岩体与黑云母花岗岩体分别形成于426.3±1.9Ma和425.1±1.8Ma。对花岗岩的岩石地球化学研究表明,中天山托克逊南—库米什北志留纪—早泥盆世花岗岩为钙碱系列,轻稀土富集,微量元素洋脊花岗岩标准化具有Rb、Th、Ba富集,Ta、Nb亏损的分配型式,形成于火山弧环境;石炭—二叠纪花岗岩为钙碱系列,准铝—过铝质花岗岩,轻稀土富集程度较前者低,微量元素洋脊花岗岩标准化具有Rb、Th富集,Ba略亏损和高场强元素亏损的特点,形成于后碰撞(post-collision)构造环境。伊犁石炭—二叠纪裂谷带中石炭—二叠纪花岗岩为过铝质花岗岩,轻稀土富集,微量元素洋脊花岗岩标准化分配型式同样具有Rb、Th富集,Ba明显亏损和高场强元素亏损的特点,亦形成于后碰撞(post-collision)构造环境。南天山库尔干花岗岩为Al2O3含量高的钙碱性系列、过铝质花岗岩,稀土元素含量中等(157.89×10-6~81.81×10-6),轻稀土富集,Eu负异常明显,微量元素洋脊花岗岩标准化呈现出K、Rb、Th、Ba富集和Nb、Ta、Zr、Hf高场强元素亏损的特点,其形成时代与天山古生代洋盆俯冲时限相当,为岛弧构造环境。依据Sr-Nd-Pb同位素回时计算结果,本次研究所取的花岗岩初始锶同位素比值高,介于0.70435~0.70982,εNd(t)值多小于零或为很低的正值,T2DM或TDM均远大于岩体形成年龄,δ18O‰多大于10,个别为6.7,显示出古老壳源物质在花岗岩浆的形成过程中起了重要作用。同时,鉴于花岗岩的εNd(t)均在0左右变动,同样说明,新生地壳在花岗岩浆的形成过程中同样起着重要作用。花岗岩的εNd(t)值与前寒武纪岩石的εNd(t)对比研究表明,中天山库米什北志留纪斜长花岗岩体可能是中新元古界斜长角闪岩部分熔融的产物,而石炭—二叠纪花岗岩既有中新元古界片麻岩或片岩部分熔融生成,亦有新生地壳部分熔融受到古老地壳混染后岩浆结晶产物。伊犁石炭—二叠纪花岗岩和南天山库尔干志留纪花岗岩均显示出新生地壳部分熔融,并受古老地壳混染的Nd同位素信息。 相似文献
2.
广西大瑶山隆起罗平花岗岩的主体岩性为花岗闪长斑岩、斑状花岗闪长岩、花岗闪长岩和石英二长斑岩。三件花岗闪长斑岩的LA-ICP-MS锆石U-Pb定年结果分别为(442.8±5.8)Ma、(443.4±4.8)Ma和(442.9±5.3)Ma,为加里东期侵入体。罗平花岗岩具有高硅钠低铁镁的主量元素特征,为准铝质到弱过铝质的钙碱性系列岩石(σ43:0.89~2.09)。具有右倾型的稀土配分曲线,总稀土含量为6 8.11×10~(-6)~199.45×10~(-6),中等的负铕异常(δEu:0.59~0.85)。原始地幔标准化蛛网图中,相对富集Rb、Th、U等元素,相对亏损Ba、Nb、Ta、P和Ti等元素。岩石地球化学特征表明罗平花岗岩为I型花岗岩。罗平花岗岩的ε_(Sr)(t)为32.65~93.55、ε_(Nd)(t)为-6~-0.036,亏损地幔模式年龄(T_(2DM))为(1.17~1.67)Ga,Sr、Nd同位素表明罗平花岗岩来自于中元古代地壳物质的部分熔融。构造环境判别图解显示罗平花岗岩形成于碰撞构造环境,可能与加里东期南侧云开古陆的北向碰撞有关。 相似文献
3.
浙江东南印支晚期的构造伸展事件：来自诸暨大爽岩体的证据 总被引：1，自引：0，他引：1
出露于浙江省东南部的大爽岩体为黑云母二长花岗岩,LA-ICP-MS锆石U-Pb年代学研究表明该岩体形成于227±2Ma,属印支晚期岩浆作用的产物。地球化学分析显示该岩石低Na2O、富K2O,A/CNK=1.26~1.49(大于1.1),为强过铝质、钾玄质系列花岗岩;岩石稀土总量较高,富Sr(Sr=874.6×10-6~1158×10-6),贫Yb(Yb=3.00×10-6~3.92×10-6),富轻稀土而亏损重稀土,具轻微的负铕异常(δEu=0.68~0.70);相对富集Rb、Th等大离子亲石元素,而亏损Nb、Ta等高场强元素;Sr-Nd同位素分析表明岩石具有较高的初始锶比值(I Sr=0.710718~0.711008)和较低εNd(t)值(εNd(t)=-10.9~-11.1),上述地球化学特征指示该岩体岩浆源区为古老的地壳物质。综合分析认为大爽岩体是古老地壳部分减压熔融的产物,受控于印支造山后的伸展应力作用。 相似文献
4.
对甜水海地块东北部阿克萨依矽卡岩型铁矿区内与矿化有关的二长花岗岩开展LA-ICP-MS锆石U-Pb年代学、全岩主微量元素、Sr-Nd-Pb同位素及锆石Lu-Hf同位素研究,旨在厘定花岗岩的形成时代、岩石成因及成矿动力学背景。LA-ICP-MS锆石U-Pb定年结果表明,二长花岗岩侵位年龄为12.37±0.18 Ma(中新世高拉瓦尔期)。地球化学特征表明二长花岗岩属准铝质?弱过铝质高钾钙碱性?钾玄岩系列,具有高Sr(432~1174μg/g),低Y(3.08~18.11μg/g)和Yb(0.35~1.39μg/g)以及高Sr/Y值(64.8~203)的埃达克岩特征。在Harker图解上SiO2与其他主量元素呈负相关关系,La/Sm-La以及La/Yb-La图解显示具有分离结晶趋势,表明岩浆演化以分离结晶为主。二长花岗岩SiO2与Y、Yb呈负相关关系而与Sr/Y值呈正相关关系,并且矿区内存在同源同期闪长玢岩,因此认为阿克萨依二长花岗岩的埃达克岩性质是玄武质岩浆的分离结晶作用引起的。全岩Sr-Nd-Pb同位素分析表明,阿克萨依二长花岗岩与青藏高原北部地球化学省具有相似的同位素组成特征,岩浆起源于受俯冲板片交代的富集地幔,而变化范围较大的εHf(t)值以及较低的Mg#暗示岩石侵位过程中受到地壳混染。结合前人研究,我们认为阿克萨依二长花岗岩及相关的矽卡岩铁矿形成于中新世西昆仑受巨型地幔低速体上涌影响的伸展构造背景下。 相似文献
5.
为确定东昆仑祁漫塔格乌兰乌珠尔地区片麻状黑云母花岗岩和二长花岗岩的形成时代、岩石成因、源区性质和构造背景,对该岩石样品进行了锆石U-Pb年代学、地球化学和锆石Hf同位素研究.结果显示:片麻状黑云母花岗岩加权平均年龄为457.5±2.3 Ma,铝饱和指数A/CNK介于0.98~1.02,属准铝质岩石,Na2O/K2O比值为0.440~0.625,属于高钾钙碱性系列.二长花岗岩加权平均年龄为422.5±1.6 Ma,铝饱和指数A/CNK介于1.03~1.05,属弱过铝质岩石.二者均具有高硅(SiO2介于68.93%~74.72%)、高碱(全碱ALK介于6.83%~9.40%)、低磷(P2O5小于0.12%)等特征.富集轻稀土元素,亏损重稀土元素,δEu值为0.29~0.70,显示Eu中度负异常.富集Rb、K等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素,属于I型花岗岩.二长花岗岩样品的εHf(t)值为-2.2~+1.4,二阶段模式年龄为1 320~1 546 Ma.结合岩石成岩年龄、地球化学特征及区域构造演化认为片麻状黑云母花岗岩(457.5±2.3 Ma)为下地壳部分熔融产物,形成于原特提斯洋向北俯冲导致的局部拉张环境.二长花岗岩(422.5±1.6 Ma)岩浆来源于中元古代新增生的下部地壳熔融产物,形成于碰撞拼贴后的伸展构造环境. 相似文献
6.
本文对广西梧州思委银矿区思委岩体中细粒黑云母二长花岗岩进行了系统的锆石U-Pb年代学、岩石地球化学和Hf同位素分析研究,以深入探讨其岩石成因。LA-ICP-MS锆石U-Pb定年获得了思委岩体黑云母二长花岗岩成岩年龄为165±1Ma。思委岩体黑云母二长花岗岩为一套弱过铝质高钾钙碱性系列花岗岩,富集U、K、Pb等元素,亏损Nb、Ta、P、Ti等元素;球粒陨石标准化REE配分模式为右倾斜配分模式,轻重稀土元素分异强烈,富集轻稀土元素,重稀土元素平坦分布。锆石Hf同位素分析花岗岩锆石ε_(Hf)(t)值分布在-15.9~8.7之间,Hf同位素二阶段模式年龄(t2DM)在652~2255Ma之间,表明岩浆源区既有直接源于亏损地幔分异的新生地壳的迅速重熔,也有不同比例的古老地壳的混合作用。花岗岩成岩可能是受古太平洋板块持续俯冲作用影响,焊接板片开裂形成的岩浆上侵。 相似文献
7.
《矿产与地质》2017,(5)
大瑶山成矿带大黎花岗岩体主要岩性为花岗闪长斑岩、花岗闪长岩、二长花岗岩和二长花岗斑岩。岩体侵入于寒武系黄洞口组,两个花岗闪长斑岩的LA-ICP-MS锆石U-Pb定年结果为(99.5±1.4)Ma和(102.3±1.5)Ma,为早白垩世的岩浆活动产物。常量元素具有高硅、富碱、富钙的特点,为钙碱性准铝质系列岩石,显示I型花岗岩的特征。稀土元素具有右倾型的配分模式,∑REE为150.63×10-6~192.13×10-6,轻微的负铕异常,δEu值为0.73~0.85。微量元素富集Rb、U、Th、La、Ce等大离子亲石元素(LILE),亏损Nb、Ta、Ti、P等高场强元素(HFS)。大黎花岗岩的初始Sr比值为0.7076~0.7078,~(147)Sm/~(144)Nd值是0.0960~0.1055,(~(143)Nd/~(144)Nd)i值为0.5122~0.5123,εNd(t)值为-5.29~-3.55,模式年龄T1DM为0.98~1.12Ga;矫正后的~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb、~(208)Pb/~(204)Pb值分别为18.0745~18.2316、15.6241~15.664、38.4129~38.5852;上述Sr-Nd-Pb同位素特征表明大黎岩体的成岩物质来自于上地壳物质的部分熔融。构造环境判别图解中,大黎花岗岩体形成于一种碰撞的构造环境,可能与燕山晚期古太平洋板块的碰撞作用有关系。 相似文献
8.
辽东卧龙泉岩体锆石U-Pb年龄、地球化学、Sr-Nd-Pb同位素特征及其构造意义 总被引：1，自引：0，他引：1
《地质学报》2015,(10)
对辽东卧龙泉黑云二长花岗岩进行锆石U-Pb定年、岩石地球化学和Sr-Nd-Pb同位素研究,以探讨岩石成因及动力学意义。LA-ICPMS锆石U-Pb定年结果显示卧龙泉岩体侵位时代为早侏罗世(194.0±1.0Ma,MSWD=1.3)。岩石地球化学特征显示,岩石具有高硅(71.49%~72.24%)、富碱(7.58%~7.83%)、贫镁(0.454%~0.497%)特点,属于高钾钙碱性系列,A/CNK值介于1.07~1.10之间,属于弱过铝质I型花岗岩,岩石富集大离子亲石元素(如K、Rb)和轻稀土元素(LREE),亏损高场强元素(如Nb、Ta、P、Ti)。同位素方面,岩石具有高的(87 Sr/86 Sr)i比值(0.71309~0.71410)和低的εNd(t)值(-15.6~-17.6);Pb同位素组成相对均一,(206Pb/204Pb)t为17.751~17.825,(207Pb/204Pb)t为15.542~15.557,(208 Pb/204 Pb)t为38.888~39.203;Sr-Nd-Pb同位素和岩石地球化学表明,卧龙泉岩体由俯冲作用引起的加厚地壳部分熔融形成。结合区域构造演化,认为卧龙泉岩体乃至华北东部侏罗纪花岗质岩浆作用可能形成于古太平洋板块向欧亚大陆俯冲、陆壳挤压和华北板块与西伯利亚板块南北挤压碰撞双重构造环境。 相似文献
9.
大兴安岭北部伊图里河地区二长花岗岩的成因及构造背景 总被引：1，自引：0，他引：1
本文对大兴安岭北段伊图里河地区黑云二长花岗岩进行了系统的地球化学及锆石U-Pb同位素年代学研究,旨在查明其成岩时代及岩石成因,并探讨其构造意义。研究结果表明,该黑云二长花岗岩的LA-ICP-MS锆石U-Pb年龄为123.3±0.8Ma,表明其形成时代为早白垩世晚期。岩石具有具有高硅、富钾、富铝的特征,A/CNK比值较大(0.96~0.99),痕量元素具有轻稀土富集、重稀土亏损、富集Rb、K等大离子亲石元素和Th、Ce、Zr、Hf等高场强元素,贫Sr、P、Ti、Ba的特征。以上特征表明伊图里河地区花岗岩为具钾玄质系列岩石特征的铝质A型花岗岩,为中下地壳岩石部分熔融的产物,该期岩浆侵位活动可能发生在早白垩世晚期东部古太平洋板块向欧亚板块俯冲作用下的弧后伸展环境。 相似文献
10.
内蒙古东部央格力雅山岩体岩性为正长花岗岩、二长花岗岩和英云闪长岩。正长花岗岩U-Pb年龄为130.4±1.1Ma,英云闪长岩U-Pb年龄为126.6±3.0Ma、二长花岗岩锆石U-Pb年龄分别为131.6±1.1Ma和130.7±1.5Ma,显示岩体侵位时间为早白垩世。地球化学研究表明,该花岗岩体具有富硅、富碱、贫钙的特征,属准铝质-过铝质高钾钙碱性系列岩石;稀土元素总量较低、轻重稀土元素分馏明显,(La/Nb)N值在9.14～24.86之间、正Eu异常显著(δEu值为1.03～1.53);微量元素K、La、Sr、Gd等明显富集,Nb、Pr、P、Ti等亏损;大离子亲石元素相对高场强元素富集。岩石分异指数平均为80.63,岩石成因类型属高分异I型花岗岩,岩浆来源于下地壳岩石的部分熔融,形成于伸展环境,与古太平洋板块俯冲作用密切相关。 相似文献
11.
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。 相似文献
12.
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
13.
郯庐断裂南段研究进展与断裂性质讨论 总被引：13，自引：3，他引：13
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。 相似文献
14.
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
15.
16.
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
17.
Jiayu Rong Michael Melchin S. Henry Williams Tatyana N. Koren Jacques Verniers 《《幕》》2008,31(3):315-318
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. 相似文献
18.
Dean S. Oliver 《Mathematical Geology》1998,30(7):911-933
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. 相似文献
19.
Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
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″. 相似文献
20.
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base. 相似文献