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1.
苏玉平  唐红峰  丛峰 《矿物学报》2008,28(2):117-126
新疆东准噶尔卡拉麦里构造带分布有多种类型花岗岩,主要包括花岗闪长岩、二长花岗岩、碱长花岗岩和碱性花岗岩.对其中最大的碱性花岗岩体(黄羊山岩体)进行定年和地球化学组成研究,结果显示,岩体的年龄约为305 Ma,岩石富含钠质角闪石(钠闪石、钠铁闪石)和少量霓石,具低铝、富碱、贫钙镁及低铁的主量元素特征,其微量元素明显富集Rb、Th等大离子亲石元素和Zr、Hf等高场强元素而强烈亏损元素Ba、Sr、Eu,稀土元素配分模式呈典型的平坦‘V'字型.这些矿物学和地球化学组成特征表明黄羊山碱性花岗岩属于典型的A型花岗岩.认为幔源岩浆高度分异、麻粒岩相残留岩及I型英云闪长质-花岗闪长质岩石部分熔融等A型花岗岩成岩模式不能解释黄羊山碱性花岗岩的成因.根据岩石的εNd(t)= 5.9~ 6.5,比当时洋壳的εNd(t)值低3~4个ε单位,认为形成该岩体的岩浆可能来源于花岗闪长质岩浆的分异结晶,而花岗闪长质岩浆则主要是玄武质洋壳和少量大洋沉积物(约5%)部分熔融的产物.  相似文献   

2.
新疆东准噶尔老鸦泉岩体的锆石U-Pb年龄和地球化学组成   总被引:5,自引:0,他引:5  
韩宇捷  唐红峰  甘林 《矿物学报》2012,32(2):193-199
老鸦泉岩体是贝勒库都克锡矿带内最大的花岗岩体,它主要由黑云母钾长花岗岩组成。通过对2件样品的锆石LA-ICP-MS U-Pb同位素年龄测定,获得其206Pb/238U年龄值分别为301±2 Ma和300±5 Ma,指示该岩体侵位时代为晚石炭世。岩石地球化学组成表明,老鸦泉碱长花岗岩具有富硅、富碱,相对富集Rb、K、Th、U、Nd、Hf等元素,而贫Ba、Sr、P、Ti等元素,具强负Eu异常,总体显示A型花岗岩的地球化学特征。锆石U-Pb年龄及岩石地球化学特征都表明老鸦泉岩体的形成与晚石炭世北疆强烈的后碰撞岩浆活动有着密切关系。  相似文献   

3.
大兴安岭新林镇岩体的同位素特征及其地质意义   总被引:6,自引:0,他引:6  
新林镇岩体位于大兴安岭北部,主要由花岗闪长岩、石英二长岩、二长花岗岩、碱长花岗岩组成,局部见到细粒辉长岩和闪长岩包体。岩石地球化学和岩石学特征表明,该杂岩体属于高钾钙碱性I型花岗岩。两个花岗闪长岩的锆石LA-ICP-MS U-Pb定年结果分别为(132±3)Ma和(131±3)Ma,属于早白垩世岩浆活动的产物。样品的Sr-Nd同位素组成比较均一,而Hf同位素特征变化较大,其εHf(t)变化介于1.32~8.32之间,Hf模式年龄与Nd模式年龄一致,表明花岗质岩浆主要起源于元古代增生的地壳物质,在岩石形成过程中有地幔组分的贡献。岩体的同位素特征将额尔古纳地块地壳增生时间限定在新元古代,而兴安地块地壳增生发生在新元古代—显生宙,暗示它们具有不同的地壳演化过程。  相似文献   

4.
新疆西准噶尔拉巴花岗岩地球化学特征及年代学研究   总被引:4,自引:0,他引:4  
新疆西准噶尔玛依勒地区的拉巴岩体侵入于下石炭统包古图组中,由花岗闪长岩、石英闪长岩、英云闪长岩、花岗岩组成,以花岗岩为主。其中花岗岩和花岗闪长岩属钙碱性、高钾钙碱性系列,为偏铝质至过铝质岩石,并具有轻稀土-大离子亲石元素富集、Nb-Ta-Ti等高场强元素亏损的地球化学特征。该岩体两个代表样品的锆石La-ICP-MS法206Pb/238U加权平均年龄分别为287±5Ma和295.1±2.3Ma,表明岩体的结晶年龄为早二叠世,与西准噶尔地区后碰撞花岗岩的时代(年龄峰值310~295Ma)相近。综合岩体的地质、地球化学特征和区域地质特征,认为拉巴花岗岩体为准噶尔地区后碰撞阶段伸展期的岩浆活动产物。  相似文献   

5.
漳浦复式岩体是一个主要由辉石闪长岩、石英(二长)闪长岩、花岗闪长岩、二长花岗岩、正长花岗岩及晶洞碱长花岗岩组成的大型中生代复式岩体。通过详细的室内外调查研究,根据侵入体之间及其与围岩的接触关系、岩石的矿物成分及岩石化学、结构构造、地球化学等特征,以成分演化单元为基本单位,漳浦复式岩体可划分出早侏罗世—晚白垩世共16个基本单元,归并为古美山、漳浦、漳洲3个超单元及4个独立单元。R1R2图解及巴尔巴林岩浆构造分类,漳浦复式岩体中各超单元(单元)侵入岩分别形成于不同的构造环境。据岩浆演化及其与区域构造演化的关系,该复式岩体是早侏罗世、晚侏罗世、晚侏罗世晚期—早白垩世、早白垩世及晚白垩世等5个构造—岩浆活动旋回岩浆活动的产物。  相似文献   

6.
对冈底斯中部地区二云母花岗岩和花岗闪长岩进行了LA-ICP-MS锆石U-Pb定年、主量元素、微量元素和锆石Hf同位素组成的测定.结果表明,二云母花岗岩的岩浆结晶年龄为(205±1)Ma,岩石属于强过铝质花岗岩,A/CNK=1.16~1.20,K2O/Na2O=1.67~1.95.岩石富Rb、Th和U等元素,Eu/Eu*=0.29~0.41,(La/Yb)N=22.62~35.08.锆石εHf(t)=-12.4~-1.8.二云母花岗岩的岩浆产生于地壳中泥质岩类在无外来流体加入的情况下云母类矿物脱水反应所诱发的部分熔融作用,其岩石形成机制类似于喜马拉雅新生代淡色花岗岩.花岗闪长岩的岩浆结晶年龄为(202±1)Ma,岩石属于准铝质(A/CNK=0.96~0.98),K2O/Na2O=1.42~1.77,Eu/Eu*=0.54~0.65,(La/Yb)N=6.76~13.35.锆石εHf(t)=-8.2~-5.5.根据花岗闪长岩的地球化学特征和锆石Hf同位素组成,花岗闪长岩的岩浆来自于地壳中基性岩类的部分熔融.冈底斯印支晚期强过铝质花岗岩的确定,表明了冈底斯在印支晚期以前曾发生地壳的缩短与加厚作用,从而进一步明确了冈底斯印支早期的造山事件及冈底斯经历了多期造山作用的演化.  相似文献   

7.
王世伟  袁峰  王彪  姜伦 《岩石学报》2018,34(1):241-254
舒家店岩体位于长江中下游成矿带中部的铜陵断隆区,与繁昌断凹区(盆地)临近,主要的岩浆岩岩石类型有辉石闪长岩、石英闪长斑岩和花岗闪长岩等。正长花岗岩为舒家店岩体深部新发现的岩石类型,其矿物组合与岩体内其他类型岩石明显不同,其形成的背景存在争议。本文通过对岩体中正长花岗岩的锆石LA-ICP MS精确定年、Hf同位素和地球化学组成分析,研究舒家店岩体正长花岗岩的年代学、岩浆源区等问题。研究显示舒家店岩体为"异源同体"的复式岩体,岩体中的正长花岗岩的侵入时间为126.5±1.6Ma~129.8±2.4Ma,明显晚于早期的辉石闪长岩和石英闪长斑岩(138.2±4.6Ma~143.7±1.7Ma),也明显晚于舒家店斑岩型铜矿床的形成时代。全岩元素地球化学和锆石Hf同位素组成指示舒家店岩体中正长花岗岩为叠加到早期辉石闪长岩及石英闪长斑岩之上的后期岩浆活动的产物,可能与繁昌盆地内花岗岩有相同的源区,为新元古代新生地壳(类似新元古花岗岩)部分熔融的产物,其岩浆源区处于高温低压的环境,相较于辉石闪长岩和石英闪长斑岩起源更浅,指示长江中下游成矿带在145~123Ma地壳处于不断减薄的过程。  相似文献   

8.
辽宁兴城新立屯地区岩浆杂岩主要由4种不同的岩石单元组成,分别为似斑状黑云母二长花岗岩,中细粒石英闪长岩,花岗细晶岩和花岗伟晶岩,前两者分布广泛且为研究区的主要岩石单元,后两者则呈脉状侵入到前两者中。应用LA-ICP-MS锆石U-Pb定年方法,测得似斑状黑云母二长花岗岩,中细粒石英闪长岩及花岗细晶岩的年龄分别为2 496±18 Ma,2 490±19 Ma,2 479±29 Ma,形成于古元古代早期。结合野外地质特征,侵位顺序由早到晚依次为:似斑状黑云母二长花岗岩,中细粒石英闪长岩,花岗细晶岩,花岗伟晶岩。岩石地球化学特征显示,新立屯地区岩浆杂岩主量元素方面具高硅(SiO2=61.38%~74.99%),富碱(Na2O+K2O=6.86%~9.41%),富Mg#(56~70)特征;A/CNK=0.91~1.18,属准铝质-过铝质岩石;微量元素方面,相对富集轻稀土元素,亏损重稀土元素,具有Eu异常(δEu=0.50~0.96);富集大离子亲石元素,亏损高场强元素;锆石Lu-Hf同位素特征εHf(t)值为-1.12~+6.13;TDM2(Hf)介于2 594~2 937 Ma,显示该套岩浆杂岩可能为地幔物质加入新生地壳再造的产物。  相似文献   

9.
皖南地区青阳-九华山复式岩体的成因   总被引:3,自引:1,他引:2  
范羽  周涛发  张达玉  袁峰  范裕  任志 《岩石学报》2016,32(2):419-438
复式岩体是指不同时代花岗岩类侵入体在空间上的共生。对复式岩体的研究,有助于了解不同时代花岗岩类的形成和分布与构造演化的关系,从而阐明花岗岩浆侵入、定位的机制。皖南地区广泛发育燕山期复式岩体,本文对该区最大和最具代表性的青阳-九华山复式岩体的地质概况、成岩年代和地球化学特征进行研究,探讨复式岩体的成因和侵位机制。锆石U-Pb定年结果表明,该复式岩体从早到晚四个阶段岩浆岩年龄分别为第一阶段花岗闪长岩143.3±1.0Ma,第二阶段二长花岗岩137.6±1.5Ma,第三阶段钾长花岗岩131.3±1.2Ma,第四阶段花岗斑岩132.0±2.0Ma。所有岩石均属于高钾钙碱性、准铝质-弱过铝质系列,从花岗闪长岩-二长花岗岩-钾长花岗岩-花岗斑岩显示出由钙碱性向碱性过渡的特征,并具有向富K、Si和贫Ca、Mg、Fe演化的趋势。该复式岩体源自同一个初始岩浆房,不同阶段岩浆沿相同的通道先后上升侵位至相邻空间叠加形成复式岩体的格局,这也是本区此类复式岩体的形成机制。早期形成的花岗闪长岩-二长花岗岩主要源自下地壳岩石的部分熔融,而晚期岩浆房中加入了较早期更多的底侵幔源岩浆,并与之完全混合,在上升侵位过程中经历了更强的分离结晶和地壳同化混染作用,形成钾长花岗岩-花岗斑岩。早期的花岗闪长岩-二长花岗岩形成与晚侏罗世古太平洋板块的俯冲作用密切相关,晚期钾长花岗岩-花岗斑岩形成于陆内拉张环境,反映出研究区从与太平洋板块俯冲有关的挤压环境向陆内岩石圈伸展环境的转变。  相似文献   

10.
喻思斌  邱检生  王睿强 《岩石学报》2016,32(12):3597-3612
本文报道了冈底斯中段达居复式岩体的锆石U-Pb年龄与Hf同位素组成,以及全岩元素地球化学组成,据此探讨了岩浆的形成机制与演化过程,进而全面揭示了岩体的成因。根据岩性和岩相特征,达居复式岩体可区分为昌那和桑嘎两个单元,前者岩性主要为花岗闪长岩,岩体内含丰富的闪长质包体;后者岩性主要为中细粒二长花岗岩,岩性总体较均匀。锆石LA-ICP-MS U-Pb定年结果表明,昌那单元花岗闪长岩和其中的闪长质包体具有一致的成岩年龄,分别为52.7±0.7Ma和52.3±0.6Ma,桑嘎单元二长花岗岩的成岩年龄为45.3±0.7Ma。地球化学组成上,二单元岩石均具有亚碱、准铝的特征,碱铝指数(AKI值)多低于0.9,铝饱和指数(A/NKC值)均小于1.0,属于准铝质钙碱性I型花岗岩。它们均富集轻稀土和大离子亲石元素(如Rb,Pb),亏损高场强元素(如Nb,Ta,Ti),具有弧型岩浆岩的地球化学组成特征。与昌那单元岩石相比,桑嘎单元岩石富硅、富碱,具有较高的Rb/Sr、Rb/Ba比值,并表现出较显著的Eu负异常,指示其经历了较高程度的分异演化。昌那单元花岗闪长岩和其中的闪长质包体具有一致亏损的Hf同位素组成,二者的ε_(Hf)(t)值分别为+4.6~+11.5和+5.0~+11.1,桑嘎单元总体也具有亏损的Hf同位素组成,但其ε_(Hf)(t)值具有较大的变化范围(-0.5~+14.7)。综合分析表明,昌那单元岩石应为底侵的亏损地幔岩浆与其诱发初生地壳熔融产生的岩浆经混合作用形成,桑嘎单元岩石为这一混源岩浆经进一步分异演化后侵位结晶的产物,且成岩过程中极可能有古老的印度地壳物质参与。  相似文献   

11.
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.  相似文献   

12.
Robert L. Linnen   《Lithos》2005,80(1-4):267-280
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.  相似文献   

13.
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.  相似文献   

14.
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).  相似文献   

15.
正The Kuqa depression deposited thick rock salt,which has a lower density than surrounding rocks.When salt bodies form a certain scale,obvious negative gravity anomalies can be detected in the surface.Therefore,gravitational method can quickly obtain the shape,plane distribution of deep-seated salt bodies and overall tectonic morphology of the basin.  相似文献   

16.
正1 Introduction The Pingluoba brine,which characterized as high concentration with sodium,potassium,boron,lithium,and rubidium,possess great development value.The main composition of the brine can be summarized to the  相似文献   

17.
正1 Introduction In the present paper,MgCl2·6H2O,FeCl3·6H2O,and CeCl3·6H2O were used as raw materials in the precipitationhydrothermal method to synthesize MgF eC e hydrotalcite.The effects of the Fe:Ce molar ratio on the composition,crystal structure,and thermal stability of hydrotalcite are examined.Energy-dispersive X-ray spectroscopy(EDS),X-  相似文献   

18.
正1 Introduction Crystallization is one of important unit operations in the chemical production process,which requires not only the crystal product with high purity and yield,but also the available particle size of the crystal products to ensure product quality.Crystallization process is affected by  相似文献   

19.
正Dear Authors and Readers:First of all,on behalf of the new Editorial Board,I would like to express our sincere appreciation for your continuing support of our journal.This journal,founded in 1922,is the oldest geological journal in China.As the flagship journal of the Geological Society of China,it has become more and more influential in earth sciences in China and beyond.The journal is now indexed by SCI,CA and more than 20 other databases,with an impact  相似文献   

20.
正20141283 Bai Daoyuan(Hunan Institute of Geological Survey,Changsha 410016,China);Zhong Xiang Nature,Origin and Tectonic Setting of Jinzhou Basin in the South Segment of Xuefeng Orogen(Geology in China,ISSN1000-3657,CN11-1167/P,40(4),2013,p.1079-1091,10 illus.,47 refs.)Key words:foreland basins,strike-slip faults,Hunan Province  相似文献   

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