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1.
山西省石墙区铝土矿地质与地球化学特征研究 总被引：2，自引：0，他引：2
[摘 要]山西省原平市石墙区铝土矿属于典型的喀斯特型铝土矿。含矿岩系自下而上包括铁质粘土层、铝土矿层、粘土层,且含矿岩系一般包含两个明显的沉积旋回。矿体主体呈层状、似层状产出,矿石结构以隐晶质结构为主,局部出现碎屑和豆鲕粒结构。矿石构造大都为块状构造。矿物学分析显示,硬水铝石、针铁矿、锐钛矿、高岭石是主要的组成矿物,另外还含有石英、伊利石、绿泥石等矿物。地球化学分析显示,主量元素主要包括Al2O3、SiO2、Fe2O3、H2O+及TiO2,微量元素中碱性和碱土元素Li、Sr、Be、Cs、Ba 及酸土元素Zr、Hf、Nb、Ta、W 均表现为明显富集,且Zr 和Hf 之间以及Nb 和Ta 之间具有高度的相关性。地球化学指标Zr/ Hf、Nb/ Ta 以及Eu/ Eu*- TiO2/ Al2O3图解显示,底板碳酸盐岩是山西省原平市石墙区铝土矿的重要源岩。 相似文献
2.
Xuefei Liu Qingfei Wang Jun Deng Qizuan Zhang Silei Sun Jianyin Meng 《Journal of Geochemical Exploration》2010
The Dajia Salento-type bauxite deposit in western Guangxi is hosted within the Quaternary ferrallitic soil profile, and it formed via breaking up, weathering and oxidizing of Permian bauxite orebodies occurring as a semi-continuous layer in the upper Permian. Mineralogical analyses reveal that diaspore, hematite and kaolinite are the major minerals in bauxite ores with small amounts of anatase, chamosite, gibbsite, goethite, illite, zircon, quartz and pyrite. The ore texture and mineral assemblage reveal that the depositional/diagenetic environment of the Dajia bauxite was much close to phreatic environment. Both the ore texture and the morphology of zircon grains also indicate that most of the bauxitic soils were transported a short distance. Diaspore is suggested to be non-metamorphic in origin and mainly formed in a reducing condition of diagenetic environment, while kaolinite is the product of the in situ epigenetic replacement of alumina in diaspore by dissolved silica. Geochemical analyses indicate that Al2O3, Fe2O3, SiO2 and TiO2 are the main components of the bauxite ores and trace elements such as Zr, Hf, Nb, Ta, Th and U were enriched during the bauxitization process. Simultaneously, Zr vs. Hf and Nb vs. Ta show a high correlation. Geochemical indices such as Zr/Hf, Nb/Ta and Eu/Eu* (among others) denote that the magmatic rocks related to the Emeishan plume in western Guangxi and the carbonates in the underlying Maokou Formation provided the main sources of material for the bauxite ores. 相似文献
3.
桂西田阳堆积型铝土矿矿物学及地球化学 总被引：1，自引：0，他引：1
[摘 要]桂西田阳堆积型铝土矿产于第四纪红土层中。本文通过对桂西田阳第四系堆积型铝土矿进行一系列矿物学与地球化学研究,探索铝土矿的物质来源。矿物学分析显示铝土矿石中主要矿物为硬水铝石、赤铁矿和锐钛矿,含有少量高岭石、鲕绿泥石、三水铝石、针铁矿、金红石、伊利石、蒙脱石和石英等。地球化学分析显示,组成铝土矿石的主要化学组分有Al2O3、Fe2O3、SiO2、TiO2、FeO 和H2O+;微量元素分析显示,铝土矿石相对地壳和原始地幔富集B、Li、Ga、Zr、Hf、Nb、Ta、W、Th、U 等元素,而亏损Ni、Cr 等元素。矿石中明显富集稀土元素,稀土总量变化大,轻重稀土分异明显,轻稀土元素富集明显;矿石具有明显的铈异常和铕异常,且铕异常相对稳定,为一致的负异常。元素相关性分析显示常量元素间相关性较差;部分微量元素如Zr、Hf、Nb 和Ta 间呈现出较高的正相关性。通过Zr/ Hf、Nb/ Ta 图解、Eu/ Eu* - TiO2/ Al2O3图解和Zr-Cr-Ga 图解综合分析显示铝土矿物质来源复杂,底板碳酸盐岩和周围火成岩都为铝土矿提供物源。 相似文献
4.
华北克拉通在中奥陶世至晚石炭世期间一直出露地表,经历了长期的风化作用,形成大规模的铁-铝黏土矿,其成矿物源一直是研究的热点,尤其是本溪组底部铁矿和铁质黏土矿与上部铝黏土矿是否为同一来源尚未查清。本研究选取克拉通南缘大安铝黏土矿床作为研究对象,展开微区矿物及元素地球化学组成分析,进一步探讨铁-铝黏土矿物质来源。大安矿床内含矿岩系自下而上包括铁质黏土岩、铝土矿、铝质黏土矿;局部喀斯特高地缺失铝土矿,铝质黏土矿直接覆盖于铁质黏土岩之上。铁质黏土岩在洼地以菱铁矿、黄铁矿和伊利石为主,在隆起区以赤铁矿、伊利石和高岭石为主。铝土矿以硬水铝石、伊利石和锐钛矿为主;铝质黏土矿主要矿物为伊利石。矿物微区分析在黏土矿底部发现大量的碳化硅和少量自然硅、硅铁矿、铬铁矿;区域对比揭示北秦岭造山带内商丹缝合带和二郎坪群中的蛇绿岩为铝黏土矿形成提供了成矿物质。本溪组底部铁质黏土与上部铝黏土矿稳定元素比率(例如Zr/TiO2、Hf/TiO2、Nb/TiO2、Ta/TiO2)存在明显差异,揭示二者为不同来源: 底部铁质黏土岩和铁矿层为底板碳酸盐岩原地风化的产物;而上部铝黏土矿是异地搬运物,北秦岭造山带在晚石炭世的整体抬升为华北铝黏土矿形成提供了重要的成矿物质。 相似文献
5.
重庆南川-武隆铝土矿属于渝南-黔北铝土矿成矿带,为喀斯特型铝土矿床。经显微镜、X射线粉晶衍射、矿物自动分析仪（MLA）、扫面电子显微镜等方法对该矿床矿物学的研究,发现组成铝土矿的主要矿物为一水硬铝石、高岭石、绿泥石,次要矿物为伊利石、一水软铝石、三水铝石、鲕绿泥石、菱铁矿、赤铁矿、针铁矿、黄铁矿、锐钛矿、金红石、磷灰石、石英、锆石、方解石、长石及稀土矿物等。矿石组构及矿物组合表明形成铝土矿的沉积/成岩环境为接近于潜流的环境。矿石结构和锆石形态指示成矿物质经过了短距离的搬运。地球化学研究结果显示,组成铝土矿的主要化学成分为Al2O3、TFeO、SiO2和TiO2,铝土矿化过程中REE、Zr、Hf、Nb、Ta、Th、Sc、Li和Ga发生富集。形成铝土矿的母岩物质主要来自下伏页岩的风化作用,灰岩和酸性火山岩对铝土矿的形成也有一定的贡献。结合稳定同位素资料,认为铝土矿的形成可能与生物作用有关。 相似文献
6.
Provenance of iron,bauxite and clay deposits of the Carboniferous Benxi Formation in southern margin of North China Craton: An example from Da'an bauxite and clay deposit of Sanmenxia area,Henan Province 
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下载免费PDF全文 Liu Xue-Fei Wang Qing-Fei Ma Yao Li Zhong-Ming Zhao Li-Hua Zhou Zhi-Hui Liu Bai-Shun Ma Xin-Li 《古地理学报》1999,22(5):965-976
During the Middle Ordovician to Late Carboniferous period,the North China Craton(NCC)was exposed and experienced prolonged weathering that resulted in the formation of large-scale iron,clay and bauxite deposits. The source of ore-forming material has always been a research focus,in particular,whether the sources of the iron ore and the Fe-bearing clay at the bottom of Benxi Formation are the same as the upper bauxite and clay deposit is still unclear. In this study,the Da'an bauxite and clay deposit at the southern margin of the NCC was chosen to carry out a detailed analysis of the micro-region mineral composition and elemental geochemical characteristics for further exploring the sources of iron,bauxite and clay deposits. The composition of the ore-bearing rocks in the Da'an bauxite deposit from the bottom to top includes Fe-bearing clay(locally iron ore),bauxite,and bauxitic clay;locally,in karstic uplift,bauxitic clay layer is directly overlying on the Fe-bearing clay. The Fe-bearing clay is dominated by siderite,pyrite,and illite in the karstic depression,and hematite,illite,and kaolinite in the uplift. Bauxite is mainly composed of diaspore,illite,and anatase,while bauxitic clay is mainly composed of illite. Mineral microanalysis revealed the development of large amounts of moissanite and small amounts of natural silica,silicalite,and chromite at the bottom of bauxitic clay layer. Regional comparison and correlation reveal that the ophiolite in the Shangdan suture zone and Erlangping Group in the North Qinling orogenic belt(NQOB)likely provides source materials for bauxite and clay deposits. The obvious differences in immobile element ratios (e.g., Zr/TiO2,Hf/TiO2,Nb/TiO2,Ta/TiO2)between the bottom Fe-bearing clay layer and the upper bauxite and clay layer in Da'an deposit,revealing that they are from different sources. The bottom Fe-bearing clay and iron ore layers are the products of in-situ weathering of underlying carbonates,while the top bauxite and clay are allochthonous. The regional uplift of the NQOB during the Late Carboniferous period provided important ore-forming materials for the formation of the NCC bauxite and clay deposits. 相似文献
7.
The present study focuses on the Late Cretaceous Bidgol bauxite deposit in the Zagros Simply Fold Belt, SW Iran. The orebody is located in the eroded major NW–SE trending Koh-e-Hosseyn anticline and hosted as discontinuous stratified layers and lenses within the upper member of the Cenomanian–Turonian Sarvak Formation. Detailed mineralogical analysis reveals that diaspore, hematite, goethite, anatase, clinochlore, chamosite, and calcite are the major mineral components accompanied by minor amounts of detrital and REE-bearing minerals such as rutile, zircon and parisite. The ore texture suggest that the bauxite material has an authigenic origin but in some parts it has been transported short distances from a primary in situ environment and redeposited in karstic depressions. The spheroidal pisolites of the Bidgol bauxite formed under conditions of low water activity, favouring the formation of large diaspore cores and a single dry-to-wet climatic fluctuation. The mass change calculations relative to the immobile element Ti show that elements such as Si, Fe, Mg, K, Na and Sr are leached out of the weathered system; Al, Ni, Zr, Ga, Cr and Ba are concentrated in the residual system; and Hf, Ta, Co, Rb, Cs, Be, and U are relatively immobile during the bauxitisation processes. The Nb, Th, Y, V, Sc, Sn and ΣREE are relatively immobile in the initial stage of bauxitisation processes in the bauxite ores, but were slightly mobile at the later stage of bauxitisation. Geochemical data reveal progressive enrichment of the REE and intense LREE/HREE fractionation toward the lower parts of the bauxite profile. Cerium behaves differently from the other REEs (especially LREE) and show positive anomalies in the upper horizons that gradually become negative in the deeper parts of the profile. The distribution and fractionation of trace elements and REEs during the bauxitisation process in the Bidgol deposit are mainly controlled by the presence of REE-bearing minerals, fluctuations in soil solution pH, REE ionization potential and the presence of bicarbonates or organic matter. Geochemical analyses confirm a protolith contribution from the bedrock argillaceous limestone and suggest that the source material for the Bidgol bauxite was provided from a siliciclastic material derived from a continental margin. The mid-Turonian uplift led to the formation of karstic topography, rubbly breccia and a layer of ferruginous–argillaceous debris that was affected by lateritic weathering under humid tropical climate. Subsequently, mobile elements are removed from the profiles, while Al, Fe and Ti are enriched, resulting in the formation of the pristine bauxite materials. When the platform subsided into the water again, the pristine bauxitic materials were partly converted to bauxite. During the exposure of bauxite orebodies on the limbs and crests of anticlines and subsequent eroding and accumulation in the karstic depressions during folding and faulting in Oligocene–Miocene, important factors such as intensity of the weathering, drainage and floating flow may have improved the qualities of the bauxite ores. 相似文献
8.
Permian karstic bauxite and its Quaternary derivative, in western Guangxi, southwestern, South China Block, possess a total tonnage greater than 0.5 billion tons. The primary late Permian karstic bauxite formed in reduced environment in the background of Tethyan accretionary orogenesis. And as one consequence of Cenozoic convergence of the Indian and Eurasia continents, the primary orebody was uplifted, eroded and re-sedimented within Quaternary laterite. The geochemical variation and its controls during the ore transformation from Permian to Quaternary remain poorly understood. Quaternary ore blocks comprise an inner zone of fresh ore, and then it gradually transited through a middle zone to a margin with extensive weathering. One such bauxite block was selected and further subdivided into twenty-three samples for geochemical and mineralogical analysis. The inner and middle zones contain similar mineralogical compositions, dominated by diaspore and amesite, with minor illite, anatase, goethite, pyrite, zircon, and rutile. The margin is composed of diaspore, with small amounts of amesite, boehmite, illite, goethite, anatase, kaolinite, zircon, rutile, and barite. Bauxite in all three zones is composed of mainly Al, Si, Fe, and Ti, and high contents of Zr, Cr, Li, F, S, Zn, V, Sr, Nb, Ba, and REE. Variations in Fe2+ and Fe3+ between the three zones were observed. The elements Si, Al, Fe2+, Mg, Ba, Cr, F, Li, Ni, Zn, and REE decrease from the core of the ore block outwards, corresponding to an increase in S and Fe3+. Depletions in Si, Al, Fe2+, Mg, Ba, and Cr were caused by the dissolution of amesite. Most of the Al and Si in amesite were lost during the weathering, and minor retained to form kaolinite. Depletions in Li, Ni, and Zn resulted from changes in the depositional environment between the late Permian and Quaternary. Dissolution of REE-bearing fluorocarbonates resulted in depletions of REE and F. The enrichment of Fe3+ and S was related to the precipitation of goethite, hematite, and barite in an oxidizing environment, while local enrichment of Ce resulted from the redox change of Ce3+ → Ce4+ under the same condition. This shows that the chemical composition of laterite enwrapping the bauxite also took part in Quaternary bauxite transformation. This study shows that the elements migrations during bauxite transformation were influenced by multiple independent factors except for the elemental attributes. 相似文献
9.
滇东南地区晚二叠世铝土矿属典型的喀斯特型铝土矿,矿体赋存于上二叠统吴家坪组(龙潭组),分析其地球化学特征对研究其物质来源具有重要意义。全岩分析显示铝土矿石成分以Al2O3、Fe2O3、SiO2和TiO2为主,其中Al2O3与Fe2O3 、SiO2具有较好的负相关关系。微量元素Cr、Zr、 Hf、Ta、Th、U和稀土元素在铝土矿矿化过程中不断富集,元素Zr-Hf、Nb-Ta之间具有明显的正相关关系。lgCr-lgNi图解、稳定元素比值(Zr/Hf)及稀土元素配分模式等地球化学特征说明峨眉山玄武岩为铝土矿的形成提供了主要的物质来源,同时下伏碳酸盐岩也提供了部分成矿物质。 相似文献
10.
The Mandan and Deh-now bauxite deposits are located 40 km northeast of the Dehdasht city in the Zagros simply fold belt. These deposits occur in eroded major NW–SE trending anticlines and occupy karst cavities near or at the boundary between the Sarvak and Ilam Formations. Local uplifts at the end of the Cenomanian and the mid-Turonian caused erosion and karstification of the Sarvak Formation. These unconformities in the Upper Cretaceous favoured the formation and enrichment of bauxite deposits in the Zagros fold belt. The bauxite sequence in the Mandan deposit consists of white, gray, black, pisolitic, red, and yellow bauxites. This sequence was repeated in the Deh-Now area, but without gray and black bauxites. The present mineralogical studies of the Sarvak Formation and the Mandan and Deh-now bauxite deposits indicate oxidizing to reducing conditions during the Upper Cretaceous in the Zagros fold belt, which had a significant effect on the compositions of the bauxites. At least two phases of bauxitization can be distinguished in the study area: (i) an oxidizing phase represented by boehmite, diaspore, hematite and kaolinite; and (ii) a reducing phase represented by pyrite and chlorite. Geochemical data show that trace elements, like Zr, Hf, Nb, Ta, Th, and U, were enriched during bauxitization. The bauxite deposits and carbonate rocks show similar REE patterns, namely they are enriched in REEs although the LREEs are more enriched than the HREEs. Mass change calculations demonstrate that Mg, Mn, Ca, K, and P2O5 were leached out of the weathered system whereas Al, Fe, and Si become concentrated in the residual system. This study indicates that the Mandan and Deh-now deposits are karst-type bauxites formed by karstification and weathering of the Sarvak Formation. 相似文献
11.
[摘 要] 河南三门峡市贯沟铝土矿属喀斯特型铝土矿。研究区内地层发育相对完全,除上奥陶统、
志留系、泥盆系和下石炭统地层缺失外,从太古界到新生界均有出露。铝土矿层主要产出于中石炭系本
溪组下段。矿石以鲕粒和隐晶质结构为主,少量碎屑结构。矿物学分析显示,铝土矿矿石的主要组成矿
物有硬水铝石、锐钛矿、伊利石,另外,还包括少部分高岭石、锆石等。硬水铝石呈隐晶质结构组成矿石
的基质,少部分呈现细小的板状、长柱状形态。锐钛矿存在两种形态:第一种是锐钛矿与硬水铝石二者
同期形成;第二种锐钛矿以脉状穿插在硬水铝石组成的基质中,形成稍晚于硬水铝石。伊利石主要呈鳞
片状集合体形态组成矿石的基质。锆石主要分散在硬水铝石组成的基质中。进一步研究发现:硬水铝
石电子探针分析显示晶体中存在Fe、Si 和Ti 等其它元素,其主体呈隐晶质与锐钛矿密切共生,指示硬水
铝石主要为简单的成岩结晶成因。矿石中的锐钛矿和硬水铝石共生,互相包含和穿插,反映大量的锐钛
矿是成矿期或成岩期结晶形成。对风化作用中形成的伊利石主要由云母转化而形成,该过程中矿物结
构并未发生明显改变。 相似文献
12.
13.
白云岩风化剖面元素地球化学特征:对黔中九架炉组“三稀金属”富集机制的启示 总被引：2，自引：1，他引：1
黔中早石炭世九架炉组铝土矿含矿岩系富集Ti、Li、Sc、V、Ga、Nb、Ta、Zr、Hf、Th和稀土(REEs)等"三稀金属",具有成为独立矿床或伴生资源的潜力。这些元素大部分与九架炉组共有同一母岩,且富集程度受母岩的成分和风化作用控制。本研究选取九架炉组母岩乌当娄山关群白云岩和纳雍牛蹄塘组泥质白云岩的现代风化剖面为研究对象,研究元素在风化作用过程中的迁移特征及分布规律,进而为九架炉组微量元素的富集机制提供启示。研究获得以下认识:1)依据剖面结构、ZrHf、Nb-Ta、Y-Ho二元图特征及REE配分曲线和Eu/Eu*值的相似性表明研究区土层主要来源于基底或母岩的风化; 2)白云岩风化成土过程中Si、Fe、Cr、As、Sb、Ti、Nb、Ta、Zr、Hf、Th、REEs等元素化学性质相对稳定,富集程度较高,而Ca、Mg、Na、K、Sr、P、Mo、Cd等元素化学性质活泼,容易淋失亏损; 3)纳雍剖面REEs~(3+)和Ca~(2+)半径差与REEs富集系数相关性良好,表明碳酸盐岩风化过程中,含钙矿物磷灰石是稀土元素分配的重要控制因素; 4)九架炉组的母岩也是Ti、Li、Sc、V、Ga、Nb、Ta、Zr、Hf、Th等微量元素的主要物质来源,母岩风化过程中,这些微量元素首先在副矿物、黏土矿物、铝矿物及磷灰石等矿物相中初步富集,之后随风化碎屑物一起沉积形成微量元素超常富集地层; 5)纳雍剖面地表和地下水提供了部分P、Be、Zn、Sb、Pb、Y及REEs来源,指示水体迁入作用也是九架炉组REEs富集的重要原因。研究表明黔中九架炉组微量元素的来源较复杂,风化-沉积过程中,化学性质稳定的元素残留在风化碎屑物中并被搬运-沉积在负地形中,而化学性质活泼的元素首先被带入水体,在沉积-成岩过程中特定条件下发生二次富集作用(例如次生矿物的形成及吸附)形成微量元素富集的地层。 相似文献
14.
A previous study briefly described the occurrence of a new type of Nb(Ta)-Zr(Hf)-REY-Ga (REY: rare earth elements and yttrium) polymetallic mineralization in eastern Yunnan, southwest China. In this paper, the mineralogical and geochemical features have been further advanced through a study of two regionally extensive and relatively flat-lying mineralized layers from No. XW drill core. The layers are clay-altered volcanic ash and tuffaceous clay, and are dominated by clay minerals (mixed layer illite/smectite, kaolinite, berthierine, and chamosite); with lesser amounts of quartz and variable amounts of anatase, siderite and calcite; along with trace pyrite, barite, zircon, ilmenite, galena, chalcopyrite, and REE-bearing minerals. The mineralized samples have higher Al2O3/TiO2 values (13.7–41.4) and abundant rare metal elements (Nb, Ta, Zr, Hf, REE, Ga, Th, and U) whereas less mineralized samples are rich in V, Cr, Co, and Ni and have lower Al2O3/TiO2 values (2.32–7.67). The mineralized samples also have strong negative δEu in chondrite-normalized REE patterns. Two processes are most likely responsible for the geochemical and mineralogical anomalies of the mineralized samples: airborne volcanic ash and multi-stage injection of low-temperature hydrothermal fluids. Based on paragenetic analysis, this polymetallic mineralization is derived from the interaction between alkaline volcanic ashes and subsequent percolation of low-temperature fluids. The intense and extensive alkaline volcanism of the early Late Permian inferred from this study possibly originated from the coeval Emeishan large igneous province (ELIP). This unique Nb(Ta)-Zr(Hf)-REE-Ga mineralization style has significant economic and geological potential for the study of mineralization of the lowest Xuanwei Formation. 相似文献
15.
河南省新安县郁山铝土矿床地质特征 总被引：2，自引：0，他引：2
[摘 要] 郁山铝土矿矿床是豫西典型的隐伏铝土矿床,本文以西郁山矿段为主较系统阐述了矿床
地质、矿体和矿石特征等。矿体赋存于本溪组铁铝质泥岩建造中下覆马家沟组岩溶特征控制矿体的形
态,矿体深部延伸受架子沟背斜及断层控制,其上覆地层控制矿体的埋深。矿体厚度空间变化大,A/ S
与含铝岩系厚度及矿体厚度相关性很小。矿石以鲕粒和泥晶结构为主,少部分具有“砾中鲕冶结构,显示
矿床形成过程中的风化与搬运的复合过程。矿石主要含铝矿物是一水硬铝石(42%～88%),其次是粘
土矿物(高岭石和伊利石);黄铁矿、菱铁矿较普遍分布于下部矿石中,显示矿石形成于还原性沉积洼地
中。铝土矿共伴生有益矿产和元素价值大。本文对进一步研究河南省隐伏铝土矿床有较重要参考意
义。 相似文献
16.
云南文山县天生桥地区铝土矿是典型的沉积型铝土矿,矿体赋存于上二叠统龙潭组,其下伏地层为上石炭统灰岩或与峨眉山大火成岩省有关的玄武岩。矿石以泥晶结构为主,含少量粒屑结构与鲕粒结构;矿石的结构特征表明风化物质可能经过短距离的搬运。常量元素分析结果显示铝土矿石中Al2O3分别与Fe2O3 和TiO2具有较好的负相关关系。在铝土矿矿化过程中,微量元素Zr、Hf、Nb、Ta和Bi相对于Li、Rb、Sr、Ba不断富集。元素Zr、Hf、Nb、Ta 分别与TiO2显示较高的相关性。运用稳定元素相关性(如Zr-Hf、Nb-Ta)、lgNi和lgCr二元图解以及稀土元素配分模式等方法探讨矿床成矿物质来源,研究结果表明玄武岩为铝土矿的形成提供了主要的物质来源,下伏碳酸盐岩可能也提供了少量的物质来源。 相似文献
17.
云南省丘北县大铁中型铝土矿是近年来在滇东南地区新发现并探明的一水硬铝石沉积型铝土矿床,矿体赋存于上二叠统龙潭组下段。通过矿相学分析,对大铁铝土矿矿石的矿物组成和主要矿物的赋存状态进行了系统研究。研究结果表明,矿石主要矿物组成为一水硬铝石,其次是高岭石、伊利石、绢云母、绿泥石、锐钛矿、赤铁矿、针铁矿、金红石、玉髓等。一水硬铝石呈现出多种结晶形态和复杂的赋存状态,其嵌布特征主要有以下5种：①呈自形、半自形粒状不均匀地嵌布在脉石矿物中;②呈豆状、土豆状、豆鲕状产出;③呈隐晶质、微晶集合体或极不规则的粒状、微粒状产出;④呈脉状、骸晶状产出;⑤一水硬铝石与铝凝胶或脉石矿物的集合体呈环带状或同心圆状产出。 相似文献
18.
[摘 要] 滇东南地区上二叠统吴家坪阶下部铝土矿不整合于峨眉山玄武岩或灰岩之上,查明其物质来源对铝土矿勘探具有重要意义。对铝土矿及峨眉山大火成岩省玄武岩、花岗岩及下伏灰岩的地球化学指标进行研究,结果表明:滇东南铝土矿常量元素主要由SiO2、Fe2O3、Al2O3、TiO2 和FeO 组成;铝土矿中富集Zr、Hf、Nb、Ta 元素,表明Zr、Hf、Nb、Ta 等高场强元素在滇东南地区铝土矿矿化过程中较为稳定,且Zr、Hf、Nb、Ta 表现出良好的相关性;铝土矿球粒陨石标准化曲线与峨眉山玄武岩配分曲线趋势一致,均富集轻稀土元素,而与下伏灰岩差异较大,且Zr-Hf、Nb-Ta 图解与峨眉山玄武岩呈线性关系,而与矮郎河过铝质花岗岩的相关性不强。据此推断滇东南地区上二叠统吴家坪阶下部铝土矿主要物质来源为峨眉山玄武岩。 相似文献
19.
《Chemical Geology》2003,193(1-2):109-125
Ilmenite separates from the floor (LS), roof (UBS), and wall (MBS) sequences of the Skaergaard Intrusion were analyzed for major and trace elements using DCP-AES and ICP-MS techniques. In all three sequences, FeO progressively increases, and MgO and Al2O3 progressively decrease with differentiation. Although trace element abundances are, in general, higher in UBS ilmenite than in MBS and LS ilmenite, all three sequences have similar trends for trace element abundance vs. crystallization. Ba, Cs, Rb, Sr, Th, U, Y, and the REEs are excluded elements in ilmenite, and remained at low abundances during differentiation. Cr, Ni, Sc, and V are included elements in ilmenite and other mafic phases, and decreased during differentiation. V contents in ilmenite, however, do not decrease significantly until the upper part of the middle zone, suggesting that magnetite did not begin to affect the magma differentiation trend until much later than when it first appears in the intrusion. Hf, Nb, Ta, and Zr, which are strongly excluded elements in silicates, are included elements in ilmenite. The element ratios Zr/Hf, Y/Ho, Nb/Ta, and U/Th are relatively constant in Skaergaard ilmenite from different parts of the intrusion, suggesting that fluid transport did not significantly effect these elements during differentiation or post-solidification cooling. Calculated partition coefficients for ilmenite in the Skaergaard Intrusion are similar to those reported from previous studies of lunar and terrestrial basalts and kimberlites, and for most elements are significantly lower than those reported for ilmenite in rhyolitic magma. Similar Di's for Zr, Hf, Nb, and Ta suggest that ilmenite crystallization did not significantly affect Zr/Nb or Hf/Ta in the Skaergaard magma, but the ratios of Zr, Hf, Nb, or Ta to other high field strength elements, such as Th, U, Y, or the REEs, may have been altered by ilmenite fractionation. 相似文献