川西甲基卡308号脉的矿物学特征及其岩浆- 热液演化示踪   总被引：1，自引：0，他引：1  

王臻  陈振宇  李建康  陈毓川 《地质学报》2022,96(6):2039-2061

甲基卡稀有金属矿床是亚洲规模最大的伟晶岩型锂矿床，308号脉为其中出露面积最大的伟晶岩脉。308号脉具有完善的分带性:细粒白云母- 钠长石- 石英带（Ⅰ）、中粗粒钠长石- 石英- 微斜长石带（Ⅱ）、中粒电气石- 钠长石- 石英带（Ⅲ）、中粗粒锂辉石- 钠长石- 石英带（Ⅳ）和中细粒锂辉石- 钠长石- 石英带（Ⅴ），并且富含稀有金属矿物（如锂辉石、绿柱石、锡石和铌钽氧化物），因此是系统研究伟晶岩演化历史和成岩成矿机制的理想实验对象。308号脉的矿物学研究较为薄弱，其岩浆- 热液演化过程及该过程中熔- 流体性质的变化规律，以及稀有金属的富集过程和影响因素尚不清楚。本文选取该脉各结构带中的贯通性矿物云母、磷灰石，以及稀有金属矿物锂辉石和特征性矿物电气石，通过详细的电子探针工作，分析它们的产状、结构特征、化学组成及其变化，结果表明:① 308号脉边部Ⅰ带（高温结晶）中电气石的出现（~5%）反映伟晶岩初始熔体具有富B的特征（>2%）；锂辉石在Ⅳ和Ⅴ带内的大量结晶说明初始熔体可能具有富Li的性质；主要含氟矿物电气石、磷灰石和云母类在岩石中的含量均较低，并且原生磷灰石具有相对偏低的F浓度（<3%），仅能形成于富F环境中的锂云母矿物也十分稀少，这些特征均表明308号脉初始熔体很可能具有较低的F含量；② 伟晶岩体系演化至Ⅴ带时发生流体出溶现象，自此进入岩浆- 热液过渡阶段，出溶流体可能具有富Cs和贫F的性质；③ 原生白云母和电气石化学成分的规律性变化说明308号脉的演化过程很可能不存在外来流体的加入；④ 308号伟晶岩的成岩和锂成矿过程主要受分异结晶作用支配，有限的出溶流体规模和伟晶岩分异演化程度（仅演化至岩浆- 热液过渡阶段，未充分进入热液阶段）对锂辉石的结晶和保存都起到了重要作用。  相似文献   

广西金牙金矿含金流体的动力学迁移   总被引：2，自引：0，他引：2       下载免费PDF全文

祁士华  殷鸿福  柳建华 《地球科学》1999,24(3):308-311

根据广西金牙及右江三叠纪贫地中的众多微细浸染型金矿床的均位于三叠纪盆地水下碳酸盐台地的边缘且弧形断裂的预顶部位这一事实,作者在金牙金矿物质和成矿流体来源于沉积盆地的基础上,对台地边缘区作沉积构造分析和流体动力学分析,应用流体势理论及数字化模拟技术得出;成矿流体在压力下趋于向台地边缘斜坡且弧形断裂的弧顶部位集中。  相似文献   

Subaerial terminoglacial fans II: a semi-quantitative sedimentological analysis of the middle and distal environments     

Zieliński  T.  van Loon  A.J. 《Geologie en Mijnbouw》1999,78(1):73-85

Twenty-five fans in NE Poland, formed under subaerial terminoglacial (previously called ice-contact) conditions, were investigated to model the dominant genetic processes involved. These fans show, as do other types, a proximal, a middle and a distal subenvironment. It is found, however, that the characteristics of these subenvironments as present in subaerial terminoglacial fans differ in several respects from those in fans formed under other climatic conditions. The present study deals with the middle and distal subenvironments. These appear to be much less complex than the proximal subenvironment in this type of fan. The middle terminoglacial fan comprises two sandy facies, characterized by unchannelized transport (mainly sheet floods) and stream flows. The distal terminoglacial fan is characterized by one (sandy/silty) facies, resulting from unchannelized currents and from settling in ephemeral ponds; braided streams play a secondary part in this fan subenvironment. The characteristics of the middle and distal fan subenvironments are described and illustrated, as is the facies from the distal subenvironment. Their vertical and lateral relationships are presented in a facies model.  相似文献   

阿尔泰大型-超大型矿床富集区地壳演化   总被引：4，自引：0，他引：4  

李红阳  杨竹森  罗泰义  高振敏  王登红 《地球学报》1999,20(4):409-417

通过构造、岩浆、变质、成矿等地质作用及其时空演化规律的对比分析,以及物探重力、航磁及遥感信息的综合研究,认为古生代阿尔泰富蕴地幔热柱成因的三联点裂谷形成与演化———“手风琴式”开合,是阿尔泰大型- 超大型矿床富集区形成与演化的根本原因。地幔热柱热地幔物质大规模上涌和横向扩张,产生三联点裂谷系统,导致古大陆解体,形成阿尔泰“洋岛型”蛇绿岩、阿尔泰型花岗岩、花岗岩化、高温低压变质带和主要大型- 超大型矿床;地幔热柱活动停止或间息,导致三联点裂谷系统发生A 型俯冲而封闭造山,形成三叉式陆间造山带和同造山花岗岩、  相似文献   

生物中碳氢化合物的结晶（英文）     

Mara.  AA 《地学前缘》1999,6(1):0-0

文章专门讨论与特定成岩作用伴生的铬、铂和硫化物矿床形成的内生因素。该类成岩作用对矿石富集有显著影响。矿床的巨大规模起因于与广泛强烈的成岩过程有关的特殊的成矿作用。这些作用导致产在超基性杂岩中的特殊纯橄榄岩（铬矿石）、基性超基性层状侵入体中的低硫层和铁镁橄榄石纯橄榄岩（铂族金属矿床）的形成,以及富铁火成分异岩的透岩浆硫化作用（Ｃｕ Ｎｉ硫化物和Ｃｕ Ｚｎ Ｐｂ硫化物矿石）。还根据巨型矿床的成因模型提出了矿物学岩石学的找矿标志  相似文献   

鄂东南铜,铁矿床地质—地球物理—地球化学勘查模式   总被引：1，自引：0，他引：1  

郭学全 《地质学报》1994,68(1):62-70

本文是在鄂东南地区以铜为主的多金属矿床的实际资料基础上，按矿床类型归纳，分别建立了铁山式铁－铜矿床，铜绿山式铜－铁矿床，叶花香式铜矿床，鸡冠嘴式铜－多矿床和铜山口式铜（钼）矿床等典型矿床的地质－地球物理－地球化学勘查模式。这些模式系统地总结了该区铜矿床的成矿地质条件，地球物理和地球化学特征，并以图示的形式表现出来，对该区今后的铜矿床研究及矿产预测、找矿方法的选择和就矿找矿等方面有一定的现实意义。  相似文献   

浙西北火山盆地铀矿主要类型,产出条件及找矿方向     

周家志 《铀矿地质》1994,10(1):32-39

本文根据铀矿化特点，将浙西北火山盆地铀矿划分为３种类型，即沉积（成岩）型、热液脉型及沉积－热液叠加改造型（层控型）铀矿。系统地总结了不同类型铀矿的地质特征及产出条件，探讨了各类铀矿的成因联系及成矿模式，指明了火山盆地铀矿的找矿方向及途径。  相似文献   

福建浦城中生代铀,多金属矿床形成条件及构造环境分析     

聂淦波  隆盛银 《华东地质学院学报》1994,17(2):106-116

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Averno tuff ring in Campi Flegrei (south Italy)     

G. Mastrolorenzo 《Bulletin of Volcanology》1994,56(6-7):561-572

The tuff ring of Averno (3700 years BP) is a wide maar-type, lake-filled volcano which formed during one of the most recent explosive eruptions inside the Campi Flegrei caldera.The eruptive products consist of (a) a basal coarse unit, intercalated ballistic fallout breccia, subplinian pumice deposits and pyroclastic surge bedsets and (b) an upper fine-grained, stratified, pyroclastic surge sequence.During the deposition of the lower unit both purely magmatic (lapilli breccia) and hydromagmatic episodes (wavy and planar bedded, fine ash pyroclastic surge bedsets) coexisted. The hydromagmatic deposits exhibit both erosive and depositional features. The upper unit mostly comprises fine grained, wet pyroclastic surge deposits. The pyroclastic surges were controlled by a highly irregular pre-existing topography, produced by volcano-tectonic dislocation of older tuff rings and cones.Both the upper and lower units show decreasing depletion of fines with increasing distance from the vent. The ballistic fallout layers, however, exhibit only a weak increase in fines with distance from the vent, in spite of marked fining of the lapilli and blocks. The deposits consist dominantly of moderately to highly vesicular juvenile material, generated by primary magmatic volatile driven fragmentation followed by episodes of near-surface magma-water interaction.The evolution of the eruption toward increased fragmentation and a more hydromagmatic character may reflect that the progressive depletion in magmatic volatiles and a decrease in conduit pressure during the last stage of the eruption, possibly associated with a widening of the vent at sea level.  相似文献   

Mineral deposit formation in Phanerozoic sedimentary basins of north-east Africa: the contribution of weathering     

Klaus Germann  Torsten Schwarz  Mario Wipki 《International Journal of Earth Sciences》1994,83(4):787-798

The intra- and epicontinental basins in north-east Africa (Egypt, Sudan) bear ample evidence of weathering processes repeatedly having contributed to the formation of mineral deposits throughout the Phanerozoic.The relict primary weathering mantle of Pan-African basement rocks consists of kaolinitic saprolite, laterite (in places bauxitic) and iron oxide crust. On the continent, the reaccumulation of eroded weathering-derived clay minerals (mainly kaolinite) occurred predominantly in fluvio-lacustrine environments, and floodplain and coastal plain deposits. Iron oxides, delivered from ferricretes, accumulated as oolitic ironstones in continental and marine sediments. Elements leached from weathering profiles accumulated in continental basins forming silcrete and alunite or in the marine environment contributing to the formation of attapulgite/saprolite and phosphorites.The Early Paleozoic Tawiga bauxitic laterite of northern Sudan gives a unique testimony of high latitude lateritic weathering under global greenhouse conditions. It formed in close spatial and temporal vicinity to the Late Ordovician glaciation in north Africa. The record of weathering products is essentially complete for the Late Cretaceous/Early Tertiary. From the continental sources in the south to the marine sinks in the north, an almost complete line of lateritic and laterite-derived deposits of bauxitic kaolin, kaolin, iron oxides and phosphates is well documented.  相似文献