共查询到20条相似文献，搜索用时 312 毫秒
1.
内蒙古文圪气镁铁-超镁铁质杂岩体中环带角闪石矿物学特征及成因 总被引：1，自引：0，他引：1
内蒙古文圪气镁铁-超镁铁杂岩体主要由辉石岩和角闪石岩组成,普遍发育角闪石环带的角闪石岩位于岩体南部,呈伟晶结构,主要由角闪石(>95%)和磷灰石(3%～5%)组成。选取环带较明显的两个角闪石样品,采用EMPA和LA-ICPMS分别做主量和微量成分剖面,环带角闪石边部为铁韭闪石,核部为韭闪石。从核部到边部,SiO2、MgO、Na2O含量逐渐降低,Al2O3、TiO2、FeOT、K2O和碱金属(Na2O+K2O)逐渐升高。中稀土、重稀土元素和Sc最大值位于核部,最小值位于边部;轻稀土元素、高场强元素、大离子亲石元素及过渡金属元素最大值位于幔边部,最小值位于核部,反映了核部氧逸度较高、温度和压力较低,边部氧逸度较低、温度和压力较高,是两期不同成分、温度、压力和氧逸度岩浆结晶的表现,并且角闪石岩受到后期高氧逸度低温热液的改造。环带角闪石的形成机理与文圪气岩体中铂族元素矿化过程相吻合。文圪气岩体与华北地台北缘中泥盆世镁铁质-超镁铁质岩具有相同的岩石组成、成因和构造背景,环带角闪石具有幔源角闪石特点,核部平均温度大于732℃,边部大于770℃,核、边部温度均小于950℃,结晶压力≤272 MPa,结晶深度≤12.4km。环带角闪石的结晶过程可能与文圪气岩体中铂族元素的成矿过程类似。 相似文献
2.
红柳沟北镁铁-超镁铁质岩体位于柴达木陆块北部的欧龙布鲁克微陆块东北缘,呈岩墙状,出露面积约0.1km~2,由方辉橄榄岩、橄榄二辉岩、含长单辉橄榄岩、橄榄辉长苏长岩、暗色橄榄辉长岩、苏长岩、辉长岩等组成,各岩相带在空间上呈渐变过渡关系。电子探针分析结果显示,岩体的主要造岩矿物为贵橄榄石、古铜辉石、普通辉石和斜长石,并且各矿物的结晶温度为1 307~1 122℃。岩体钛铁矿化明显,主要金属矿物为钛铁矿、钛磁铁矿和磁铁矿。利用橄榄石Fo最高值反演出原生岩浆MgO含量为8.49%,FeO含量为10.03%,TiO_2含量为1.63%,为普通玄武质岩浆。通过综合研究各矿物形成的温度和氧逸度条件,认为岩浆从橄榄石结晶到普通辉石结晶,其氧逸度是缓慢升高的,并且氧逸度是控制红柳沟北岩体Ti-Fe氧化物结晶的主要因素。 相似文献
3.
滔河岩体位于北大巴山地区岚皋县,滔河镁铁质岩的岩石类型与区域镁铁质岩石类型一致,主要为辉绿岩、辉长岩、辉长辉绿岩及富含钛闪石的闪长岩,各相邻镁铁质岩呈明显的渐变过渡状态,指示为同期岩浆作用的产物。闪长岩内部角闪石呈细长条状、针状巨晶产出,粒径为1~3 cm不等,自形程度较高,具有明显的高铝(Al=1.93~2.06)、高钛(Ti O2=4.54%~5.50%)特征,其种属为钛闪石。钛闪石结晶温度为1 062~1 129℃,形成深度为19.11~22.64 km,氧逸度变化范围为-0.36~-0.01,说明岩浆来源较深且上侵速度较快。钛闪石的存在指示岩体的源区在部分熔融前发生了明显的地幔交代作用,地幔交代和岩体形成都与俯冲消减作用存在内在的成因联系。岩体具有明显的深源特征、与俯冲消减作用有关及区域岩体的地壳混染特征,共同指示滔河岩体可能形成于与俯冲相关的弧后拉张环境。 相似文献
4.
5.
柞木沟铁矿床为北大巴山地区的钛磁铁矿矿床。矿区赋矿岩体为辉绿岩,主要矿物组成为单斜辉石、长石、角闪石、黑云母、钛磁铁矿和钛铁矿等。文中利用电子探针对柞木沟矿床内部典型矿石矿物组成研究发现,单斜辉石主要为普通辉石,角闪石为镁绿钙闪石和阳起石,黑云母主要为铁质黑云母,少量为镁质黑云母。柞木沟铁矿床赋矿辉绿岩母岩浆具有高碱(K2O+Na2O含量3.56％～4.79％)、高钛(TiO2含量3.50％～5.58％)特征,指示其为碱性系列岩浆。单斜辉石平衡温度为1 138～1 167 ℃,铁钛氧化物形成温度为781～808 ℃,氧逸度(lgf(O2))为-14.15～-14.36,黑云母结晶温度分为600～650 ℃和～700 ℃两个区间,氧逸度介于NNO与MH之间。矿石内部锆石SHRIMP U Pb测年结果为(437.9±3.7) Ma,与区域不含矿岩体年龄一致,说明二者为同期岩浆作用产物。矿体赋存于岩体中、矿体与含矿辉绿岩围岩呈渐变过渡关系、磁铁矿的岩浆成因、磁铁矿的矿物化学特征及氧同位素组成特征共同指示柞木沟矿床为典型岩浆矿床。北大巴山地区早古生代晚期的拉张作用,导致深部的岩浆上升并在浅部快速就位,早期结晶出少量铁钛氧化物;随着温度降低,辉石、长石、角闪石等铁镁硅酸盐矿物开始结晶,进而包含早期结晶的铁钛氧化物。岩浆的氧逸度逐渐升高以及后期富铁质流体的注入导致铁钛氧化物大量结晶,最终完成该区的成矿作用。 相似文献
6.
大别山毛屋镁铁—超镁铁岩块的原岩与超高压变质作用 总被引：6，自引：0，他引：6
毛屋镁铁－超镁铁层状岩体由方辉橄榄岩、橄榄方辉岩、含石榴石方辉岩、石榴二辉岩、石榴透辉岩、榴辉岩、绿辉石岩等不同岩性的岩石组成的变层状堆晶岩。 相似文献
7.
南海新生代碱性玄武岩中发育有角闪石捕虏晶。本文以南海新生代碱性玄武岩中的钛闪石为研究对象,对钛闪石的地球化学特征以及形成条件进行了研究,并探讨其地质意义。研究表明钛闪石是岩浆早期高压结晶的产物,其高Ti富Al,Mg#平均为0.68,形成于幔源岩浆中,成分相对于寄主岩为捕虏晶,其主微量元素的成分范围以及微量元素的配分形式与碱性玄武岩中的巨晶角闪石以及捕虏体中的脉状角闪石一致。根据其主量元素的含量,我们计算出了钛闪石形成的温压条件以及结晶深度。按结晶深度钛闪石可分为两期,一期结晶深度较大(35.09~43.74 km),位于岩石圈底部,形成压力在1019~1305 MPa,温度在1049~1066℃;另一期结晶深度相对较小(27.20~27.29 km),位于岩石圈中下部,形成压力在759~771MPa,温度在1031~1078℃。钛闪石是岩浆形成早期在不同深度发生分离结晶的结果,可能记录了导致南海新生代玄武岩由拉斑玄武岩向碱性玄武岩转变的岩石圈变厚的趋势。 相似文献
8.
对位于秦岭-大别造山带的沙坪沟钼矿矿区出露的橄榄角闪石岩开展了系统的岩石学、岩相学及电子探针原位分析,厘定了其成岩物理化学条件,并探讨了岩石成因及形成的构造环境。橄榄角闪石岩主要造岩矿物为橄榄石、角闪石、金云母和辉石;副矿物为磷灰石、铬铁尖晶石、镁铁尖晶石、磁铁矿、磁黄铁矿、镍黄铁矿等。电子探针原位分析结果显示,橄榄石属于贵橄榄石系列,角闪石主要是韭闪石,辉石为透辉石,云母为金云母。造岩矿物结晶顺序为橄榄石-辉石-角闪石,结晶温度介于1 111. 64～1 223. 30℃之间,形成压力为350～740 MPa,形成于较高的氧逸度环境(角闪石结晶时的氧逸度范围为NNO+0. 59～NNO+2. 27)。角闪石和金云母的矿物学特征显示它们均是与幔源岩浆作用相关的原生矿物,表明该套基性-超基性岩与幔源岩浆作用有关。综合分析认为,在大别造山带中生代地壳减薄的伸展构造背景下,该橄榄角闪石岩母岩浆源于地幔,是经过地幔7. 92%部分熔融的玄武质岩浆经结晶分异作用形成的幔源岩浆底侵下地壳的产物。 相似文献
9.
碱性造岩矿物能够记录碱性岩源区特征、岩浆演化以及晚期成矿的重要信息,是开展碱性岩成岩成矿研究的有效手段。波孜果尔碱性花岗岩型铌-钽-锆-铷-稀土矿床位于塔里木北缘-中亚南天山晚古生代造山带,是塔里木地块北缘铌成矿带中典型的碱性岩型矿床。本文通过对含矿岩体中的霓石和钠铁闪石开展矿物学研究,结合全岩成分揭示波孜果尔稀有-稀土金属矿床含矿岩体的岩石类型、演化特征、构造背景及成矿条件。研究发现,含矿碱性岩体由霓石钠铁闪石碱长花岗岩、霓石钠铁闪石石英碱长正长岩、霓石钠铁闪石碱长正长岩组成。不同岩相岩石均表现出相似的稀土和微量元素配分模式,以富集轻稀土元素和高场强元素,亏损大离子亲石元素和重稀土元素为特征,具有显著的负Eu异常,指示三种岩石类型是同源岩浆演化的产物。含矿岩体中的辉石为霓石-霓辉石,角闪石为钠铁闪石。霓石和钠铁闪石稀土和微量元素配分模式相似且含量都较低,富集重稀土、亏损轻稀土,具有显著的负Eu异常,并富集Zr、Hf等高场强元素,亏损Ba、Sr等大离子亲石元素。霓石和钠铁闪石微量元素特征指示三个岩相单元的演化程度由低到高依次为霓石钠铁闪石碱长花岗岩→霓石钠铁闪石石英碱长正长岩→霓石钠铁闪石碱长正长岩,且结晶分异作用控制了岩体的形成。同时,早期霓石钠铁闪石碱长花岗岩的钠铁闪石呈现Ce正异常,晚期岩相中则无异常,指示演化的早期阶段氧逸度较高,随着磁铁矿等氧化物的结晶熔体趋于还原。波孜果尔含矿岩体成矿元素除Rb外分布并不均匀,表现为演化早期的岩相富集Nb,而演化晚期的岩相更富集稀土和Zr。进一步研究发现,塔里木北缘碱性岩带发育的铌、稀土、钽、锆、铷、铀等稀有稀土金属矿化与地幔柱引起的幔源岩浆底侵有关,其构造背景可能为地幔柱对造山带的叠置。 相似文献
10.
图拉尔根、香山和天宇、白石泉岩浆铜镍硫化物矿床分别位于新疆东天山的觉罗塔格构造带和中天山地块,角闪石在这些矿床中均以贯通矿物产出。本研究通过这些矿床角闪石的主量和微量元素含量,讨论两个构造单元成矿岩浆的性质和演化过程。四个矿床的角闪石种属主要为韭闪石、镁绿钙闪石、浅闪石、钛闪石、钙镁闪石和镁闪石,结晶温度区间为940～1080℃,压力区间为250～450MPa,相当于11～15km的深度。图拉尔根和香山矿床的角闪石结晶温度和压力均相对较低(平均分别为1027℃、318MPa和1013℃、313MPa),可能与其所处的觉罗塔格构造带断裂发育,成矿母岩浆易于侵位到较浅处结晶有关。四个矿床角闪石结晶时岩浆的含水量均较高(4%左右),可能是俯冲交代作用导致的地幔源区本身水含量较高以及角闪石结晶较晚共同作用的结果。相较于觉罗塔格构造带的图拉尔根和香山矿床(0 ΔNNO 1. 7),角闪石氧逸度计指示中天山地块天宇和白石泉矿床的氧逸度变化范围大且偏低(分别是-0. 6 ΔNNO 1. 7和-0. 4 ΔNNO 1. 8)。中天山铜镍矿床的氧逸度特征及相对觉罗塔格构造带较低的微量元素Ce/Pb比值指示其岩浆侵位过程中受到的古老地块的混染作用较强。以上研究表明角闪石虽是玄武质岩浆中较晚结晶的矿物,但能为示踪铜镍矿床岩浆演化提供重要线索。 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.
15.
Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
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
16.
正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.) 相似文献
17.
正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology, 相似文献
18.
正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
19.
正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se- 相似文献
20.
正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with 相似文献