西准谢米斯台乌根萨拉钼矿地质特征及成因浅析

以西准谢米斯台山乌根萨拉钼矿为研究对象,对其基本地质特征、含矿花岗岩的岩石地球化学特征进行研究,探讨其成因。乌根萨拉矿点钼矿体呈裂隙网脉状和大脉状产于加里东期钾长花岗岩与志留系谢米斯台组凝灰岩的接触带上,明显受接触带控制,钾长花岗岩为矿体形成提供了潜在物源、热源及热液来源。含矿钾长花岗岩富硅、富碱、富铝、富钾,相对低钛及贫CaO、MgO、P_2O_5,准铝质-过铝质,为A型、S型花岗岩,形成于后造山环境。综合认为,乌根萨拉钼矿成因属与钾长花岗岩有关岩浆期后热液型,形成于志留纪晚期后造山环境板块挤压运动机制向拉张机制的转化期。     

东秦岭铜山-天目山铝质A型花岗岩特征及构造意义

铜山-天目山花岗岩地处东秦岭的桐柏北部,由铜山、天目山两个花岗岩岩基或岩株组成,分别呈北西向蝌蚪状、南东向不规律带状展布于羊册-明港断裂带南北两侧,以往被认为是S型花岗岩。研究结果表明,其岩石化学以高硅碱富钾贫钙低镁及FeOT/MgO比值高、碱性、准铝质-过铝质为特点;稀土元素总量较高,Eu亏损显著,稀土元素球粒陨石标准化分布型式呈典型的"海鸥型";微量元素中HFSE富集、Rb/Sr、Rb/Ba比值较高,Sr、Ba、Ta、P、Ti强烈亏损,属铝质A型花岗岩,明显不同于S型及I型、M型花岗岩。形成于叠覆造山期后的板内拉张环境,标志着东秦岭地壳在早白垩世中晚期仍处于伸展减薄塌陷阶段。     

内蒙古西乌旗石匠山晚侏罗世——早白垩世A型花岗岩锆石U-Pb年龄及构造环境

内蒙古西乌旗石匠山A型花岗岩位于贺根山缝合带内,侵位于早石炭世迪彦庙-白音布拉格蛇绿岩带和下二叠统寿山沟组与大石寨组中,岩性为二长花岗岩。石匠山A型花岗岩富硅(SiO_2=74.18%~77.16%)、富钾(K_2O=4.31%~5.07%)、富碱(Na_2O+K_2O=8.44%~9.16%),贫Al_2O_3、CaO、MgO、TiO_2、P_2O_5、Sr、Ba、Eu、Ti和P,具有较高的Ga/Al(3.98~6.09)、(Na_2O+K2O)/CaO、K_2O/MgO、TFeO/MgO、Rb/Nb、Y/Nb、Sc/Nb值,稀土元素配分曲线为典型的海鸥式分布,δEu为0.01~0.19,负Eu异常显著,明显不同于I、S和M型花岗岩,为典型的铝质A型花岗岩。在地球化学分类判别图解上,石匠山A型花岗岩显示A_2型后造山铝质花岗岩特征,反映其形成于后造山伸展环境。LA-ICP-MS锆石U-Pb测年结果表明,该花岗岩的侵位年龄为159.8±1.3Ma、143.1±1.3Ma、136.20±0.69Ma,即形成时代为晚侏罗世-早白垩世,揭示贺根山缝合带在晚侏罗世-早白垩世为后造山伸展阶段。     

河北省涿鹿县大河南岩体中A型花岗岩特征及构造意义

分布在大兴安岭-太行山构造岩浆活动带上的大河南岩体,是多期岩浆活动的产物,划分为晚侏罗世、早白垩世早期和早白垩世晚期三期。早白垩世侵入岩由细粒正长花岗岩、中粒正长花岗岩、花岗斑岩组成。本文通过对早白垩世侵入岩地球化学特征进行系统研究,发现该期岩体主量元素具有富硅、富碱、富铁,低镁、贫钙特征;稀土元素配分曲线为右倾"海鸥型",负铕异常明显;微量元素以Ba、Sr、P、Ti强烈亏损,K富集为特征。Y/Nb-Ce/Nb图解上,岩体具A1型花岗岩特征,形成于非造山环境的张性环境,是早白垩世华北东部岩石圈减薄、华北克拉通破坏的具体实例。     

埃塞俄比亚施瑞地区花岗岩地球化学特征及构造环境

埃塞俄比亚北部施瑞地区具有造山前、造山期和造山后3种花岗岩类型,全岩Sm-Nd等时线测年结果表明,造山前和造山后花岗岩成岩年龄分别为824.4±15.5Ma和517.9±5.8Ma.3类花岗岩主量元素和稀土微量元素成分存在明显差异,其中造山前花岗岩属于低钾过铝质花岗岩,稀土分配模式属轻稀土弱富集型,富集大离子亲石元素,亏损P和Ti高场强元素;造山期花岗岩为准铝质高钾钙碱性花岗岩,稀土分配模式属轻稀土富集型,富集大离子亲石元素和高场强元素;造山后花岗岩为弱过铝质高钾钙碱性花岗岩,稀土分配模式具强烈铕亏损的海鸥型,富集大离子亲石元素,明显亏损P和Ti高场强元素.综合研究表明:造山前和造山期花岗岩均为I型幔源花岗岩,构造环境处于被动大陆边缘-火山岛弧环境;造山后花岗岩为A2型壳源主花岗岩,是在洋盆关闭和阿拉伯-努比亚地盾成熟后,由减薄的地壳部分熔融产生.     

内蒙古西乌旗努和特早白垩世A型花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义

内蒙古西乌旗努和特A型花岗岩位于贺根山缝合带内,侵位于晚石炭世梅劳特乌拉蛇绿岩带、中二叠统哲斯组和晚石炭世英云闪长岩中,岩性为正长花岗岩。努和特A型花岗岩富硅、富钾、富碱、贫Al_2O_3、CaO、MgO、TiO_2、P_2O、Sr、Ba、Eu、Ti和P,具有较高的Ga/Al、(Na_2O+K_2O)/CaO、K_2O/MgO、TFeO/MgO、Rb/Nb、Y/Nb、Sc/Nb值,稀土元素配分曲线为海鸥式分布,δEu值为0.25~0.54,负Eu异常明显,地球化学特征明显不同于I、S和M型花岗岩,为铝质A型花岗岩。在地球化学分类判别图解上,努和特A型花岗岩显示后造山A_2型花岗岩特征,反映其形成于后造山伸展环境。LA-ICP-MS锆石U-Pb测年表明,该花岗岩的侵位年龄为130.4±1.2Ma和130.4±1.4Ma,其形成时代为早白垩世。根据蛇绿岩、俯冲-岛弧型-碰撞型和后造山型岩浆岩的时空分布与演化特征,贺根山缝合带在早白垩世可能处于后造山伸展阶段。     

中亚造山系中南段早中生代花岗岩类时空分布特征及构造环境

依据锆石U-Pb年龄,中亚造山系中南段早中生代花岗岩类大致可以划分出早中三叠世(251～227Ma)和晚三叠世—早侏罗世(226～195Ma)两个阶段。早中三叠世花岗岩类,主要分布于东天山造山带中东部、北山造山带中北部、中蒙古地块、阿尔泰造山带西段及内蒙古-吉林造山带中西部地区,多沿板块缝合带及附近展布,具有准铝质-弱过铝质的钙碱性-高钾钙碱性或弱碱性花岗岩的特点,I型、S型和A型或I-A型花岗岩均有出露,且同期的超镁铁质-镁铁质岩少见。晚三叠世—早侏罗世花岗岩类,较广泛分布于全区各造山带,具有准铝质-弱过铝质的高钾钙碱性-碱性花岗岩的特点,大都为A型和I-A型花岗岩,部分具有高分异Ⅰ型花岗岩的特点,且同期的超镁铁质-镁铁质岩较发育。早期花岗岩类的稀土元素总量(ΣREE)高于晚期,但晚期较早期具显著负铕异常,晚期花岗岩Ba、Nb、Sr、P和Ti的亏损程度较早期更明显一些。花岗岩Sr-Nd同位素特征显示,华北北缘具有非常低的εNd(t)值(-19.6～-5.4)和老的tDM值(1.23～2.09Ga),以古老陆壳为其主要源区;北蒙古-西外贝加尔造山带和内蒙古-吉林造山带主体以年轻物源为主;中蒙古地块、阿尔泰造山带、东天山造山带和北山造山带在以古老微陆块为花岗岩源区的构造背景下,有部分年轻幔源组分的贡献,总体显示出早期以壳源和幔源的双源为特点,晚期以幔源为主,从早期到晚期有年轻幔源组分递增的趋势。大量新生地壳主要分布在鄂霍茨克带及其邻区,但在一些老的微陆块上,后造山或后碰撞阶段也有较多年轻幔源岩浆的底侵而导致地壳垂向生长。早中三叠世花岗岩类在中亚造山系西部地区为后造山构造背景,东部地区为同造山作用的晚期阶段;晚三叠世—早侏罗世花岗岩类为后造山或非造山或板内伸展构造背景。     

孙吴-嘉荫地区早中生代花岗岩的年代学、地球化学与成因

对小兴安岭北部孙吴-嘉荫地区早中生代花岗岩进行了年代学和地球化学研究,据此探讨其成因及形成的构造背景。锆石U-Pb同位素定年结果表明,研究区早中生代花岗岩分为晚三叠世和早侏罗世两期,形成时代分别为210 Ma和187~181 Ma。晚三叠世碱长花岗岩属铝质A型花岗岩,岩浆源区为新元古代从亏损地幔中增生的基性火成岩地壳。早侏罗世英云闪长岩-花岗闪长岩和二长花岗岩属埃达克岩,是由加厚下地壳物质部分熔融形成的;正长花岗岩-碱长花岗岩与同期埃达克岩具明显不同的地球化学特征,岩浆源区为中元古代从亏损地幔中增生的基性地壳物质。结合区域地质构造演化特征,认为晚三叠世花岗岩是华北板块和西伯利亚板块碰撞造山后伸展构造环境下的产物,早侏罗世花岗岩的形成与古太平洋板块俯冲产生的挤压构造环境有关。     

南阿尔金茫崖A型花岗岩的成因及构造意义

南阿尔金造山带位于柴达木盆地和祁连-昆仑造山带之间,是一条重要的大陆俯冲-碰撞造山带,带中分布的大量早古生代花岗岩蕴含着造山带构造演化的重要信息。茫崖A型碱长花岗岩对限定南阿尔金进入造山后伸展环境的时限以及壳幔相互作用具有指示意义,然而该岩体的成因类型、物质来源和形成的构造环境缺乏详细研究。因此,本文利用岩相学、岩石地球化学、LA-ICP-MS U-Pb年代学和Lu-Hf同位素分析对碱长花岗岩进行系统的研究,并探讨岩浆活动对造山带构造演化的响应。碱长花岗岩显示高硅、富铁、富碱、贫钙和镁的特点,并强烈亏损Ba、Sr、P、Eu和Ti,属于A2型花岗岩;岩体的结晶年龄为403～424Ma,是中—新元古代新生地壳(新生长英质物质或钙碱性花岗岩类)部分熔融的产物,岩浆源区可能存在少量富Ca斜长石残留相;南阿尔金造山带在424Ma之后进入造山后的伸展环境,不同块体之间的均衡调整导致深部幔源物质持续上涌,造成地壳的部分熔融,形成了这一期A型花岗岩。     

埃塞俄比亚施瑞地区花岗岩地球化学特征及构造环境

埃塞俄比亚北部施瑞地区具有造山前、造山期和造山后3种花岗岩类型, 全岩Sm-Nd等时线测年结果表明, 造山前和造山后花岗岩成岩年龄分别为824.4±15.5 Ma和517.9±5.8 Ma.3类花岗岩主量元素和稀土微量元素成分存在明显差异, 其中造山前花岗岩属于低钾过铝质花岗岩, 稀土分配模式属轻稀土弱富集型, 富集大离子亲石元素, 亏损P和Ti高场强元素;造山期花岗岩为准铝质高钾钙碱性花岗岩, 稀土分配模式属轻稀土富集型, 富集大离子亲石元素和高场强元素;造山后花岗岩为弱过铝质高钾钙碱性花岗岩, 稀土分配模式具强烈铕亏损的海鸥型, 富集大离子亲石元素, 明显亏损P和Ti高场强元素.综合研究表明: 造山前和造山期花岗岩均为I型幔源花岗岩, 构造环境处于被动大陆边缘-火山岛弧环境;造山后花岗岩为A2型壳源主花岗岩, 是在洋盆关闭和阿拉伯-努比亚地盾成熟后, 由减薄的地壳部分熔融产生.      

相山铀矿田西北部与东南部地学信息对比研究

文章通过对相山铀矿田西北部与东南部地学信息的对比分析,揭示了地质结构和矿床产出特征的不均一性和不对称性的主要影响因素,为相山矿田深部找矿及远景区扩大提供了新的依据。     

中国东部岩石地球化学图

1986～1995年开展的中国东部地壳与岩石化学组成研究在中国东部(105°E以东)约330万km2的范围内系统采集了500余条标准地层剖面、800多个有代表性的火成岩体和变质杂岩体,总计28253件岩石样品,组合成2718件分析样品,对每个岩石组合样品的63种元素含量进行了准确测定,积累了大量的高质量的元素含量分析结果.选择60种元素SiO2、Al2O3、Fe2O3、FeO、MgO、CaO、Na2O、K2O、CO2、Ag、As、Au、B、Ba、Be、Bi、Cd、Cl、Co、Cr、Cs、Cu、F、Ga、Ge、Hf、Hg、Li、Mn、Mo、Nb、Ni、P、Pb、Pd、Pt、Rb、S、Sb、Sc、Se、Sn、Sr、Ta、Th、Ti、Tl、U、V、W、Zn、Zr、Y、La、Ce、Nd、Sm、Eu、Tb、Yb和Lu制作了中国东部岩石地球化学图.根据中国东部各省区区域地质志和1:50万地质图首次编制的中国东部岩石地球化学图基本反映了与特定岩石性有关的岩石地球化学元素含量分布特征、与大地构造单元有关的区域地球化学元素含量的宏观分布特征及不同大地构造单元元素含量背景的变化趋势.例如,CaO、(MgO) 、CO2和Cl的高背景反映地是碳酸盐岩地区,铁族元素Fe2O3、FeO、Mn、Ti、V、Cr、Co、Ni及MgO、Cu、Zn、P、Ga、Nb、Ta、Zr、Hf、Sc和Eu的高背景反映了基性火山岩地区,SiO2和K2O的高背景反映地是大面积分布的酸性岩石地区的地球化学特征.内蒙古兴安褶皱带为SiO2、K2O、Ag、As和Be的高背景分布区域,华北地台边缘、大别造山带和苏鲁造山带为Sr和Ba高背景分布区域,豫西台隆为Cu、Pb、W和Sc的高背景分布区域.南秦岭、西秦岭造山带以挥发性元素Hg、As、Sb、B以及Cd、Se、S的高背景显著特点.对于整个华南褶皱系而言,W、Sn、Bi、Mo、Rb、Cs、Tl、U、Th、Pb、Y和REE(Eu除外)为高背景,此外东南沿海火山岩带有是SiO2、K2O的高背景,而赣南闽西褶皱带还是碱金属Li,稀有元素Be、Nb、Ta,分散元素Cd及F的高背景.     

The eastern part of the Tasman Orogenic Zone

The eastern part of the Tasman Orogenic Zone (or Fold Belt System) comprises the Hodgkinson—Broken River Orogen (or Fold Belt) in the north and the New England Orogen (or Fold Belt) in the centre and south. The two orogens are separated by the northern part of the Thomson Orogen.The Hodgkinson—Broken River Orogen contains Ordovician to Early Carboniferous sequences of volcaniclastic flysch with subordinate shelf carbonate facies sediments. Two provinces are recognized, the Hodgkinson Province in the north and the Broken River Province in the south. Unlike the New England Orogen where no Precambrian is known, rocks of the Hodgkinson—Broken River Orogen were deposited immediately east of and in part on, Precambrian crust.The evolution of the New England Orogen spans the time range Silurian to Triassic. The orogen is orientated at an acute angle to the mainly older Thomson and Lachlan Orogens to the west, but the relationships between all three orogens are obscured by the Permian—Triassic Bowen and Sydney Basins and younger Mesozoic cover. Three provinces are recognized, the Yarrol Province in the north, the Gympie Province in the east and the New England Province in the south.Both the Yarrol and New England Provinces are divisible into two zones, western and eastern, that are now separated by major Alpine-type ultramafic belts. The western zones developed at least in part on early Palaeozoic continental crust. They comprise Late Silurian to Early Permian volcanic-arc deposits (both island-arc and terrestrial Andean types) and volcaniclastic sediments laid down on unstable continental shelves. The eastern zones probably developed on oceanic crust and comprise pelagic sediments, thick flysch sequences and ophiolite suite rocks of Silurian (or older?) to Early Permian age. The Gympie Province comprises Permian to Early Triassic volcanics and shallow marine and minor paralic sediments which are now separated from the Yarrol Province by a discontinuous serpentinite belt.In morphotectonic terms, a Pacific-type continental margin with a three-part arrangement of calcalkaline volcanic arc in the west, unstable volcaniclastic continental shelf in the centre and continental slope and oceanic basin in the east, appears to have existed in the New England Orogen and probably in the Hodgkinson—Broken River Orogen as well, through much of mid- to late Palaeozoic time. However, the easternmost part of the New England Orogen, the Gympie Province, does not fit this pattern since it lies east of deepwater flysch deposits of the Yarrol Province.     

松嫩平原西部(吉林部分)地下水资源计算与评价

选择合理的水文地质参数．对松嫩平原西部进行地下水资源计算并对供需平衡进行评价。采用补给渗入法计算大气降水补给；用断面法计算侧向迳流补给；松散岩类孔隙水采用均衡法计算；基岩裂隙水采用经验系数法及统计法进行计算。对计算结果进行分析评价，以便合理开发利用及统一管理地下水资源。     

Tectonics of the western part of the Polish Outer Carpathians

The western part of the Polish Outer Carpathians is built up from the thrust, imbricated Upper Jurassic-Neogene flysch deposits. The following Outer Carpathian nappes have been distinguished: Magura Nappe, Fore-Magura group of nappes, Silesian, Subsilesian and Skole nappes. Interpretation of seismic and magnetotelluric survey from the region South of Wadowice, allows observation of relationship between basement and flysch nappes in the Outer Carpathians. It also allows identification of dislocation cutting both flysch nappes and their basement. All the Outer Carpathian nappes are thrust over the southern part of the North European Platform. The platform basement is composed of older Precambrian metamorphic rocks belonging to the Bruno-Vistulicum terrane. Sedimentary cover consists of Paleozoic, Mesozoic and Neogene sequences. The characteristic features of this boundary are horsts and troughs of general direction NW-SE, turning W-E. Faults cutting only the consolidated basement and the Paleozoic cover were formed during the Hercynian Orogeny in the Carboniferous and the Early Permian. Most of the older normal faults were covered by allochtonous flysch nappes forming thus the blind faults. During the last stage of the geodynamic development the Carpathians thrust sheets moved towards their present position. Displacement of the Carpathians northwards is related to development of dextral strike-slip faults of N—S direction. The orientation of this strike-slip fault zones zone more or less coincides with the surface position of the major faults perpendicular to the strike of the Outer Carpathian thrustsheets. The huge fault cuts formations from the Paleozoic basement through the flysch allochton between the boreholes in Sucha Beskidzka area. The displacement of nappes of the Carpathian overthrust and diapiric extrusion of plastic formations of the lower flysch units occurred along this fault.     

Tectonics of the northern part of the Lena-Yenisey oil-bearing region

This article discusses the historical tectonic development of the portion of Siberia lying within the Arctic Circle. The exposed rocks are referred to seven tectonic or geotectonic stages: Archean, Proterozoic, Sinian, lower to middle Paleozoic, upper Paleozoic to lower Mesozoic, and Mesozoic-Cenozoic. Locally on the Shorikka and Kamennaya, the nearly horizontal Lower Cambrian beds overlie the Sinian with angular unconformity. In contrast, isolated areas on the west side of the Yenisey show a gradational relationship between the Late Sinian and Early Cambrian beds in a dominantly carbonate succession. The present tectonic elements of the Siberian platform were developed in Mesozoic-Cenozoic time, and differential movements in the basement have continued into Neogene time. The sedimentary platform cover was enlarged by sedimentary overlap from Sinian to mid-Paleozoic time. The sediment came from the older fold systems. The major structures are measured in terms of variations in stratigraphic thickness, but details are unfortunately omitted. The main features are delineated on a geotectonic map embracing 42 map units and symbols. The map lacks basic reference data, geographic designations, scale, and other essential information. — B. N. Cooper.     

吉南—辽北地区太古宙主要地质单元的含金性研究

本文基于吉南－辽北地区３６４件最新的微金分析资料,表明各主要太古宙地质单元的金丰度均明显低于地壳金丰度值。同时指出,本区绿岩带有关金矿的矿源是多源的。其中有相当一部分来自于深源。