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1.
黑云母是花岗岩中常见的造岩矿物,其化学成分可以用于判断岩体形成时的物理化学条件、岩石成因类型及构造环境。本文利用电子探针(EMPA)对武当隆起西段牌楼花岗岩中的黑云母进行了成分分析,结果发现这些黑云母Al~Ⅵ原子数较低(0.128～0.395),而Ti原子数适中(0.236～0.267),属于铁叶云母,并且均具富Fe贫Mg的特征,Fe~(2+)/(Fe~(2+)+Mg)值为0.985～0.989。岩相学观察和化学成分分析结果显示,牌楼二长花岗岩中的黑云母为岩浆成因,结晶温度为640～710℃,寄主岩体的固结压力为0.9～1.7 GPa,log f_(O_2)变化于-18.1～-17.4之间,指示其形成于低氧逸度环境中。岩浆的氧逸度较低可能是导致牌楼岩体不能形成Cu、Au和Mo矿化的决定因素,而缺乏Sn矿化可能与熔体温度较低有关。综合黑云母化学成分和岩石地球化学特征,认为牌楼似斑状二长花岗岩为A型花岗岩,侵位于非造山的伸展构造背景。 相似文献
2.
九华山花岗岩岩浆分异特征及岩石成因 总被引：10，自引：0，他引：10
利用九华山花岗岩体明显的Ｒｂ、Ｂａ、Ｓｒ变化特征、强烈亏损的中稀土元素特征以及微量元素比值蛛网图和典型的岩石化学变异特征论证了九华山花岗质岩浆的结晶分异作用,探讨了岩浆结晶分异过程对黑云母成分及锶同位素数值的影响,从而指出了岩浆分异作用可能改变Ｉ型花岗岩类的黑云母成分标型以及锶同位素初始值的原有特征。依据九华山花岗岩体相对偏高的氧化度和相对偏低的铝指数,指出九华山岩体属于Ｉ型花岗岩成因类型,九华山－青阳复式花岗岩基可以看作相似成因类型的不同时间侵位的两个岩体的复合。 相似文献
3.
本文通过电子探针分析对采自泰国北部成矿(沙蒙矿床)和贫矿(Tak岩体)花岗岩体中的黑云母开展了对比研究,以期厘清花岗岩制约锡成矿的控制因素。结果显示,成矿和贫矿花岗岩中的黑云母均属于岩浆成因,前者偏铁质,具有S型花岗岩黑云母成分特征;后者偏镁质,与I型花岗岩黑云母成分一致。利用机器学习拟合的黑云母温压计,估算成矿花岗岩早期岩浆结晶温度和压力分别为812～858℃(平均835℃)和702～882 MPa(平均781 MPa),而贫矿岩体对应的温度和压力分别为795～833℃(平均811℃)和188～373 MPa(平均226 MPa)。两类花岗岩具有明显不同的侵位深度、岩浆氧逸度和初始挥发分。研究表明,在伸展构造体制下,深部地壳的富F变沉积岩高温熔融形成的还原性岩浆,经长距离运移至较浅的深度侵位更有利于锡成矿。 相似文献
4.
扬子克拉通北缘的铁船山岩体形成于新元古代，其岩石类型为霓石－钠铁门石花岗岩，岩石富碱质、Ｓｔ、Ｆｅ、ＲＥＥ和高场强元素，而贫Ａｌ、Ｃａ、Ｍｇ、Ｓｒ、Ｂａ、Ｃｏ、Ｎｉ等组分，δＥｕ＝０．２０，Ａ／ＫＮＣ＝０．８５，Ｋ２Ｏ＋Ｎａ２Ｏ／Ａｌ２Ｏ３＝１．０９，Ａ·Ｒ＝９．２８，岩石属典型的Ａ型花岗岩，Ｎｄ、Ｓｒ和Ｏ同位素示踪反映其成岩物质来自于壳幔混合源区。根据区域地质背景的综合分析，岩体形成于活动陆缘的张裂构造环境，属活动板块边缘拉张型花岗岩。 相似文献
5.
广东塘蓬岩体中发育两类不同成因及时代的花岗岩,采用Ｒｂ－Ｓｒ等时线年龄测定,确定塘蓬主岩体的成岩时代为海西期（２０４Ｍａ）;应用Ｓｍ－Ｎｄ同位素,采用二元混合模型确定塘蓬岩体黑云母二长花岗岩为改造型花岗岩,黑云母花岗闪长岩为同熔型花岗岩。 相似文献
6.
《矿物岩石》2015,(3)
黄背岭-中鱼库钼多金属矿矿区是栾川矿集区目前的重点找矿区域。通过对黄背岭含矿斑状花岗岩与中鱼库隐伏的黑云母二长花岗岩进行岩相学观察与黑云母的化学成分特征分析,探讨了本区的岩石成因及成矿潜力。结果表明黄背岭和中鱼库花岗岩中的黑云母都属于镁质黑云母。黄背岭花岗岩中的黑云母Ti=0.15apfu~0.20apfu,具有退变质与固相线下交代成因的特征,中鱼库花岗岩中的黑云母Ti=0.27apfu~0.35apfu,具有岩浆成因的特征。从岩体浅部到深部,黄背岭岩体结晶压力为93 MPa~14 MPa,结晶深度为3.4km~0.5km。中鱼库岩体结晶压力为145 MPa~58 MPa,结晶深度为5.3km~2.1km。两岩体浅部结晶压力大,深部结晶压力小,表明两者均为快速侵入。两岩体均属壳幔混源的I型花岗岩,是深源中浅成花岗岩。两岩体形成时的温度分别为939.4℃~1 006℃,833℃~966℃,氧逸度分别为10-11.8 MPa~10-10 MPa,10-13.08 MPa~10-10.4 MPa。两者形成时的温度与氧逸度均较高,与其共存的流体都富氟,有利于钼钨多金属矿成矿。综上并结合透岩浆成矿作用的观点,认为本区成矿潜力大。 相似文献
7.
赣南寨背A型花岗岩体的地球化学特征及其构造地质意义 总被引：86，自引：9，他引：77
赣南寨背岩体主要为黑云母钾长花岗岩,黑云母结晶晚于长石和石英,锆石群型地温测量标尺显示其结晶温度为８００℃～９００℃,表明寨背岩体形成于一种高温贫水的花岗质岩浆。岩石的化学成分特点为准铝质（Ａｌ２Ｏ３为１２．２１％～１２．６２％）,富硅（ＳｉＯ２为７５．６６％～７６．７４％）,偏碱（Ｎａ２Ｏ＋Ｋ２Ｏ为７．９３％～８．９０％）,ＦｅＯＴ／ＭｇＯ值高（５９～１４８）,ＣａＯ和ＭｇＯ含量低（分别为０．１０％～０．６５％和０．０１％～０．０２％）,富含ＲＥＥ（Ｅｕ除外,ΣＲＥＥ平均为５００μｇ／ｇ）,Ｙ、Ｇａ、Ｎｂ等高场强元素（ＨＦＳＥ）以及Ｆ,Ｓｒ和Ｂａ较低。这些特点与本区的Ｉ型和Ｓ型花岗岩有明显差别,是一种典型的Ａ２型花岗岩。寨背岩体Ｒｂ－Ｓｒ等时线年龄为１７６Ｍａ,与辉长岩、双峰式火山岩有密切的时空关系,表明赣南地区在燕山早期即进入拉张裂解阶段。 相似文献
8.
业已确定，兴凯岩体沃滋涅先期克构造的锂－氟花岗岩属于Ｓ型，而东锡霍特区季格林构造的花岗岩则属于Ａ型。证实了第一种类型花岗岩流变成因和第二种类型花岗岩形成于熔体的结晶作用。采用温压地球化学方法，测定了矿石－岩浆体系在不同构造中形成时深部流体成分的差别和该成分在时间上的变化特征。探讨了伴随沃滋涅先斯克和季格林构造花岗岩的形成过程金属矿化产生差异的原因。 相似文献
9.
滇西古永地区花岗岩中黑云母成分特征及其成岩成矿意义 总被引：1，自引：0，他引：1
滇西古永地区花岗岩与锡矿床在成因上密切相关。黑云母的电子探针分析结果表明,古永黑云母二长花岗岩中的黑云母为铁质黑云母,小龙河锡矿床黑云母似斑状二长花岗岩中的黑云母为铁叶云母。两花岗岩体中黑云母总体显示出富铁(w(TFe O)=22.39%~27.91%)贫镁(w(Mg O)=1.08%~10.51%,含镁系数为0.07~0.50)的特征;但两岩体花岗岩中黑云母的化学成分具有明显的差异,古永花岗岩体中黑云母表现出相对富镁,为含幔源物质混入的I型花岗岩;而小龙河成矿花岗岩体中黑云母相对富铝贫镁,为典型壳源过铝质的S型花岗岩。古永花岗岩体和小龙河花岗岩体中黑云母的结晶温度分别为700~750℃、620~650℃,氧逸度(lgf(O2))分别为-14.0~-13.8、-17.5~-17.2。古永岩体花岗岩中黑云母结晶压力为67~120 MPa,结晶深度为2.54~4.55 km。表明本区花岗岩形成于相对高温、低氧逸度、较浅的环境。相对于古永花岗岩体,小龙河花岗岩体具有更大的Sn成矿潜力,更有利于本区锡矿床的形成。 相似文献
10.
湘南地区燕山期成矿花岗岩有3种类型,其主要造岩矿物化学成分和种属明显不同;矿物的化学成分变异特征均显示出壳幔岩浆混合成因的特点：①角闪石均属于钙质角闪石亚类。②MC型早期次花岗岩中的黑云母多属镁质黑云母;CM型晚期次花岗岩中的黑云母主要为铁质黑云母;C型花岗岩中的黑云母主要为铁叶云母-铁黑云母,且多为铁锂黑云母。3类型花岗岩中黑云母的成分变异呈线型关系,暗示有成因联系。③3类型花岗岩中斜长石有明显区别,MC型多为中长石,CM的多为更长石,C型多为钠长石。斜长石环带构造发育程度不同,CM型早期次单元花岗岩中的斜长石环带最发育。④CM型花岗岩及其暗色微粒包体中的碱性长石主要属于相对富钾的正长石,包体中的个别属歪长石,表明其形成温度较高;C型花岗岩中碱性长石为相对贫钾的钠正长石及微斜长石。⑤造岩矿物特征和成分变异显示了成矿花岗岩的形成与壳幔岩浆混合作用有关,形成MC型和CM型早期次单元花岗岩的岩浆演化主要是岩浆混合作用,而CM型花岗岩晚期次的花岗岩类和C型花岗岩类的岩浆演化可能还存在分离结晶作用。 相似文献
11.
Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
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.
Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
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
13.
The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
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
14.
Emmanuel Skourtsos Daniel Vachard Alexandra Zambetakis-Lekkas Rossana Martini Louisette Zaninetti 《Comptes Rendus Geoscience》2002,334(12):925-931
Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931. 相似文献
15.
正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.) 相似文献
16.
正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.) 相似文献
17.
正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.) 相似文献
18.
正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus., 相似文献
19.
正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an 相似文献
20.
正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of 相似文献