哈密坳陷火山岩地球化学特征分析

长期对哈密坳陷石炭系是否发育,存在较大的不确定性。通过对哈密坳陷火山岩地球化学特征分析,认为红1井石炭纪火山岩属于亚碱性系列,富钾、亏损Ti、Nb、Ta等高场强元素,即典型的"TNT"负异常,应形成于岛弧环境;红1井石炭纪火山岩的形成与北部的卡拉麦里-麦钦乌拉洋盆洋壳向南俯冲有关,在洋壳俯冲、消减、熔融作用下,喷发形成了哈尔力克岛弧,其南部的哈密坳陷应为弧后盆地。此类盆地易形成烃源岩及火山岩储层,对石炭系成藏极为有利。     

江西南部版石盆地火山岩SHRIMP锆石U-Pb年龄及其地质意义

应用SHRIMP锆石U-Pb定年方法,对江西南部三南-寻乌火山岩带版石盆地原鸡笼嶂组凝灰岩和原版石组流纹岩开展年代学研究.结果表明,凝灰岩SHRIMP锆石U-Pb年龄为(142.5±1.3)Ma,流纹岩SHRIMP锆石U-Pb年龄为(131.4±1.3)Ma.根据新的国际地层表,晚侏罗世与早白垩世的界线划在(145.5...     

哈密坳陷四道沟油气藏特征及成藏分析

四道沟低产油气藏是目前在哈密坳陷内钻探众多构造圈闭后所发现的唯一油气藏。通过对油藏构造、储层特征和油气成藏分析表明 ,四道沟构造存在二期油气运移与聚集 ,第一期形成类似哈 2井三叠系和侏罗系砂岩储层中的沥青 ,它来自三堡凹陷源岩生成的油气 ;第二期为四道沟构造上哈 2、哈 3井储层近源捕获的油气。三堡凹陷源岩在中侏罗统西山窑组沉积以后曾有较大规模的油气生成与运移 ,油气运移路线主要是向东或东北方向。储层物性差、裂缝不发育 ,早期油藏被破坏 ,后期油气源供给不足是四道沟构造上哈 2、哈 3井油气低产的主要原因。该地区下一步油气勘探应围绕三堡生油凹陷 ,以寻找未遭破坏的早期油气藏为勘探方向 ,以三叠系与侏罗系不整合附近的构造圈闭、地层圈闭、岩性圈闭和三叠纪古构造圈闭及裂缝发育带为主要勘探目标     

Initial movement of the Karakorum Fault in western Tibet： constraints from SHRIMP U-Pb dating of zircons

The Karakorum Fault zone(KFZ)plays an important role in understanding the formation,evolvement and deformation of the Tibetan Plateau.The high-T dextral shearing metamorphic rocks,e.g.,mylonites or mylonitized gneisses-granites,locally crop out along the southeastern part of the KFZ in the Ayila Ri’gyüRange area.The SHRIMP U-Pb dating of the syn-kinematic crystallized zircons indicates that the initial age of the KFZ is~27 Ma,~10 Ma older than previous results.The extensive high-T dextral shearing along the KFZ started at least at 27-20 Ma,accompanied by the syn-kinematic emplacement of leuco-granites.Deformation and concomitant fluid circulation during shearing most likely occurred as early as at 25-13 Ma.The KFZ probably grew from southeast to northwest along the fault as a result of continuous convergence between the India plate and Eurasia plate.     

临清坳陷莘县凹陷油气勘探远景评价

对莘县凹陷的构造,沉积,盆地模拟及油气勘探远景等进行了深入研究。     

吐哈盆地哈密坳陷逆断层活动性及演化

在构造解释及断层受力机制分析的基础上,根据逆断层两盘剥蚀与沉积的关系,将哈密坳陷逆断层活动的地质模型归纳为单向逆冲型、逆冲生长型和基底抬升型,并提出针对这3种类型逆断层活动量的计算方法,对主要断层在印支期、燕山期和喜山期的活动强度进行研究。结果表明:火石镇凹陷内的断层在印支期活动最为强烈,燕山期断层活动变弱,喜山期只有南部边界断层活动增强;三堡凹陷内的断层在印支期开始活动,燕山期断层活动最为强烈,喜山期断层基本停止活动;断层活动的差异性直接影响着各凹陷构造格局的形成与演化,火石镇凹陷构造格局早在印支运动就基本定型,而三堡凹陷的构造格局在晚燕山运动后才最终定型。     

河北平山深熔伟晶岩锆石成因及SHRIMP U-Pb年龄

深熔伟晶岩中的锆石具有典型的岩浆锆石的形态和结构,但却具有较低的Th/U比值,是非常特殊的,研究表明其为深熔作用所形成.进而说明并不是所有的具有自形柱状和密集振荡环带/韵律的锆石都是严格意义上的岩浆锆石.两样品锆石的SHRIMP U-Pb年龄表明伟晶岩的结晶年龄在1.87～1.89 Ga之间,大致代表了母岩深熔的时间,其核部残留的锆石年龄在2.5 Ga左右.伟晶岩形成于张性环境的浅部层次,表明陆-陆碰撞的时代可能早于1.9 Ga.     

塔西南坳陷西南缘构造类型与圈闭特征

依据构造圈闭与油气成藏理论,试图探明研究区油气聚集带的特征,利用钻探,地震研究成果,对坳陷西南缘的构造类型,圈闭特征,圈闭与油藏关系的研究,提西南缘主要发育构造圈闭,构造类型有两大6亚类,海西期和喜山期是构造圈闭和油藏的主要形成时期,论述了各二级构造单元的圈闭分布与成藏关系,提供了有利的圈闭类型和油气勘探区带。     

吐哈盆地哈密坳陷逆断层活动性及演化

在构造解释及断层受力机制分析的基础上,根据逆断层两盘剥蚀与沉积的关系,将哈密坳陷逆断层活动的地质模型归纳为单向逆冲型、逆冲生长型和基底抬升型,并提出针对这3种类型逆断层活动量的计算方法,对主要断层在印支期、燕山期和喜山期的活动强度进行研究。结果表明:火石镇凹陷内的断层在印支期活动最为强烈,燕山期断层活动变弱,喜山期只有南部边界断层活动增强;三堡凹陷内的断层在印支期开始活动,燕山期断层活动最为强烈,喜山期断层基本停止活动;断层活动的差异性直接影响着各凹陷构造格局的形成与演化,火石镇凹陷构造格局早在印支运动就基本定型,而三堡凹陷的构造格局在晚燕山运动后才最终定型。     

SHRIMP zircon U-Pb dating for volcanic rocks of the Dasi Formation in southeast Hubei Province, middle-lower reaches of the Yangtze River and its implications

The Jinniu Basin in southeast Hubei,located at the westernmost part of middle-lower val-ley of the Yangtze River,is one of the important vol-canic basins in East China. Volcanic rocks in the Jin-niu Basin are distributed mainly in the Majiashan Formation,the Lingxiang Formation and the Dasi Formation,consisting of rhyolite,basalt and basaltic andesite,(trachy)-basalt and basaltic trachy-andesite and (trachy)-andesite and (trachy)-dacite and rhyolite respectively,in which the Dasi volcanism is volumet-rically dominant and widespread. The Dasi volcanic rocks were selected for SHRIMP zircon U-Pb dating to confirm the timing of volcanism. The results indi-cate that there exist a large amount of magmatic zir-cons characterized by high U and Th contents in the volcanic rocks. The concordia ages for 13 points are 128 ± 1Ma (MSWD = 3.0). On account of the shape of zircons and Th/U ratios,this age is considered to represent the crystallization time of the Dasi volcan-ism. The volcanic rocks in the Dasi,Majiashan and Lingxiang Formations share similar trace elementand REE partition patterns as well as Sr-Nd isotopic compositions. In combination with the regional geol-ogy,it is proposed that the southeast Hubei volcanic rocks were formed mainly during the Early Creta-ceous,just like other volcanic basins in middle-lower Yangtze valley. A lithospheric extension is also sug-gested for tectonic regime in this region in the Cre-taceous Period.     

新疆东准噶尔铜华岭中酸性侵入体锆石U-Pb年代学研究

伊吾县铜华岭中酸性侵入体位于新疆北部东准噶尔阿尔曼太断裂和克拉麦里断裂之间的野马泉岛弧区, 岩性主要为闪长玢岩、英云闪长岩和二长花岗岩等。通过锆石LA-ICP-MS U-Pb年代学方法, 对这3种岩性进行精确定年, 其²⁰⁶Pb/₂₃₈U的加权平均年龄分别为427.4±3.2,422.8±3.2和418.5±2.6Ma,说明铜华岭岩体是早古生代岩浆活动的产物, 为东准噶尔早古生代造山带演化提供了花岗岩证据。     

Zircon U-Pb SHRIMP dating of the Yematan batholith in Dulan,North Qaidam,NW China

The Yematan batholith crops out over 120 km^2 in the North Qaidam ultrahigh pressure (UHP) metamorphic belt. It consists of granodiorite, monzogranite and biotite granite and forms an irregular intrusion into Neoproterozoic gneiss that has undergone Caledonian UHP metamorphism. Zircons from the Yematan granodiorite yield a SHRIMP U-Pb age of 397 3 Ma. These granitic rocks have geochemical characteristics intermediate between I- and S-type granites, and are post-collisional. We suggest that the Yematan granitic rocks were formed during the last exhumation event of the North Qaidam UHP belt.     

Zircon SHRIMP U-Pb geochronology and petrogenesis of the plagiogranites from the Lagkor Lake ophiolite, Gerze, Tibet, China

Field relationship, along with petrographical, petrological, and geochemical characteristics, and zircon populations, indicates that the plagiogranites from the Lagkor Lake ophiolite in the Bangong-Nujiang suture zone (~ 20 km south of Gerze County, central Tibet, China), derived from anatexis of hydrated gabbros by ductile shearing during transport of the oceanic crust. Therefore, this kind of plagiogranite is coeval to or little later than the spreading of the oceanic crust. Zircon SHRIMP age of 166 ± 2.5 Ma for the plagiogranites indicates that an oceanic basin existed in the western part of the Bangong-Nujiang zone in the Middle Jurassic.     

Zircon U-Pb SHRIMP ages of high-pressure granulite in Yushugou ophiolitic terrane in southern Tianshan and their tectonic implications

Zircons from two high-pressure granulite samples from the Yushugou ophiolitic terrane, southern Tian shan have been investigated by cathodoluminescence, LA ICPMS and ion microprobe (SHRIMP) for their internal textures, trace elemental compositions and in situ dating. The weighted mean ages of these two samples are 392±7 and 390±11 Ma, respectively, representing the granulite-facies meta morphic age of the ophiolitic terrane, and indicating that the southern Tianshan ocean initiated its northward subduction since the early Devonian.     

江西寻乌破火山口火山-侵入杂岩SHIRMP锆石U-Pb年龄及其地质意义

位于武夷隆起带和南岭构造带过渡部位、受NE向会昌—寻乌断裂带和EW向三南—寻乌断裂带控制的寻乌破火山口发育一套由碎斑熔岩和花岗斑岩组成的火山-侵入杂岩.SHIRMP锆石U-Pb定年结果显示,寻乌破火山口碎斑熔岩的年龄为(96.7±1.1)Ma,花岗斑岩的年龄为(97.3±0.9) Ma,根据国际地质年代表,早白垩世与晚...     

SHRIMP zircon U-Pb geochronology of Indosinian granites in Hunan Province and its petrogenetic implications

The structure, magmatism and sedimentation within the South China Block (SCB) related to the Indosinian Orogeny had attracted considerable attention since De-prat[1] and Fromagat[2] proposed the “Indosinian move-ment” based on two unconformities between Pre-Norian and Pre-Rhaetian during Triassic in Vietnam. However, Indosinian tectonic evolution of the SCB has been long debated[3―6]. Some researchers believed that the compli-cated structure-magmatism-sedimentation within the SCB w…     

西藏冈底斯带东段强母错噶石英二长岩锆石U-Pb年龄、地球化学特征及地质意义

对出露于西藏冈底斯弧背断隆带东段的强母错噶石英二长岩进行了锆石U-Pb年代学和全岩地球化学分析,并据此探讨了该岩体的形成演化过程与成岩时的大地构造背景。测试结果表明,强母错噶石英二长岩中的岩浆锆石U-Pb加权平均年龄为(50.84±0.71) Ma(MSWD=0.51)为始新世早期。石英二长岩ω(SiO_2)=64.34%～64.87%,ω(K_2O)=4.66%～4.76%,ω(Na_2O)=3.38%～3.42%,ω(CaO)=3.65%～3.72%,ω(Al_2O_3)=15.91%～16.08%,全碱含量(K_2O+Na_2O)为8.04%～8.15%,K_2O/Na_2O=1.38～1.41,属于准铝质(A/CNK=0.91～0.93)钾玄岩系列。强母错噶石英二长岩轻稀土元素(LREE)含量为(241.62～441.75)×10~(-6),重稀土元素(HREE)含量为(18.58～20.60)×10~(-6),(LREE/HREE=12.48～21.65),稀土元素配分模式为轻稀土元素强烈富集的右倾型,其(La/Yb)_N为15.38～33.79,具中等负Eu异常(δEu=0.60～0.67)。微量元素显示强母错噶石英二长岩相对富集大离子亲石元素,而Nb、Ta、Ti和P等高场强元素(HFSE)相对亏损,显示出火山弧环境背景下中等分异程度的I型花岗岩特征。强母错噶石英二长岩的形成可能与冈底斯带始新世早期强烈的岩浆作用和新特提斯洋板片断离引发的地壳增厚密切相关,大洋板片断离从而引起软流圈物质上涌,导致下地壳部分熔融并与上涌地幔混合形成壳幔混合岩浆。