共查询到18条相似文献，搜索用时 171 毫秒
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康滇地区含钒钛磁铁矿基性超基性岩体的成因类型与岩浆演化和岩体产出的地质构造条件有关。该文划分3个岩体成因类型（5个亚类）,并从矿床地质、钛铁氧化物矿物学、矿物化学和成矿温度等方面讨论它们各不相同的成矿特征。层状侵人体是最重要的成矿岩体类型。火成堆积说可以解释层状基性岩的成岩成矿机理。而层状基性超基性岩体的成因,取决于液态分异作用和结晶重力分异作用,是同源多期次侵入活动构成的复合含矿岩体。主要矿体形成受熔离作用的控制,并非结晶重力堆积的产物。 相似文献
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攀西地区层状岩体套叠式韵律的分形研究 总被引：1，自引：0，他引：1
套叠式韵律是攀西层状岩体的重要特征,它在岩相、矿物、结构、元素含量和斜长石牌号等各方面都有表现。本文阐述了套叠式韵律最为明显的岩相和元素含量特征,并采用分形中的关联维方法对白马岩体数据进行计算。从计算结果可知：形成ＭｇＯ的套叠式韵律需要有５个状态变量控制：ＳｉＯ２、ＴｉＯ２、Ｖ２Ｏ３、Ｓ等元素的套叠式韵律的形成受７个状态变量的控制,推测岩体韵律的形成受７个状态变量控制。其中有两个状态变量对ＭｇＯ影响不大。ＩｎＣ（ｒ）—Ｉｎｒ曲线近似为一直线,表明该岩体韵律可用分形的方法研究 相似文献
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《吉林大学学报(地球科学版)》2015,(Z1)
<正>攀西(攀枝花—西昌)地区出露一系列赋含大型钒钛磁铁矿矿床的基性—超基性层状岩体,它们是~260Ma峨眉山大火成岩省的重要组成部分。本文总结了攀枝花岩体的空间分布特征、岩石学与岩相学特征、岩石地球化学特征,并探讨了岩体的成因,为攀西地区关于基性—超基性岩体的研究提供理论支持。 相似文献
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大庙斜长岩杂岩体的岩石学特征 总被引：7，自引：0，他引：7
斜长岩产出可分为两类：层状型和岩体型。前者不形威独立岩体，而为层状基性-超基性杂岩中的斜长岩层。这种杂岩体具韵律性，层状构造发育，造岩矿物成分随层位有规律变化，它是基性岩浆重力结晶分异的产物，时代不限。岩体型斜长岩只产于前寒武纪，呈巨大岩体，多见于地台和地质的边缘，常与环斑花岗岩共生。它在大陆壳的分布虽不广，但其产出的构造位置、侵入的围岩、形成时代、岩性及与之共生岩石和含矿性等都有明显的共性。 相似文献
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镁铁质-超镁铁质层状岩体基本特征及岩浆作用 总被引：3，自引：0，他引：3
镁铁质-超镁铁质层状岩体可以产于多种构造环境,岩体具有典型的层状构造和韵律结构。层状岩体形成时主要的岩浆作用有重力分异作用、双扩散对流作用、压实作用、同化混染和岩浆混合作用等,其中重力分异作用很好地解释了层状岩体垂向上岩石类型的变化和矿物组分的变化,双扩散对流作用和岩浆混合作用在韵律层理形成过程中起了很重要的作用,而压实作用对岩浆演化晚期阶段补堆晶结构的形成作用明显,同化混染作用可改变岩浆的成分,导致岩浆分异产物的组成和成分的变化。堆晶结构的不同主要依赖于粒间液体的活动性和晶粥的渗透率,补堆晶结构形成需要高渗透率,而粒间液体不活动时将有利于正堆晶结构的形成。岩石组合、岩石结构、矿物组分及其变化规律很好地记录岩浆分异过程、岩浆补给等信息,可以用来讨论层状岩体的岩石成因：温度压力条件、原生岩浆及其演化过程等。 相似文献
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陈安泽 《华东地质学院学报》1980,(2)
在基性、超基性岩中有一些巨大的层状侵入体,它们与围岩多呈平行不整合或小角度相交关系,岩体厚度很大,往往超过数百米甚致数千米。巨厚的岩体由一系列互有联系的岩石类型组成。在垂向上,无论从整个岩系或局部来看,组成岩石的矿物的种类、数量、同种矿物的化学成分,都有明显的韵律性变化,往往可以组成几个至几十个大的韵律旋回。这种具有韵律性变化的层状岩体,被认为是岩浆结晶分异作用形成的“重力成层”。在一个巨大的岩浆渊中,先晶出的矿物晶体因重力分选作用依次下沉到岩浆渊底部,然后被晶体周围的残 相似文献
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根据层状含钒钛磁铁矿岩体的韵律特征及其铁质量分数变化规律,探索性地应用瑞利分馏模型模拟四川攀西地区攀枝花、红格、白马、太和等岩体成矿元素富集过程,分别建立了各岩体的统计模型和理想模型,并据此估算了铁矿石以及伴生钒、钛资源量。其中:攀枝花、红格、太和等岩体的数学模型比较一致,可能与这些岩体岩浆结晶分异比较彻底、成矿性好有关;而白马岩体的模型参数有较大差异,充分体现了该岩体结晶分异不彻底、成矿性相对较差的特点。 相似文献
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鲁西西部区域重磁异常场的分维计算与信息复合 总被引：8，自引：1，他引：8
本文利用谱分析方法计算了鲁西西部区域重磁异常场的分维数，给出了分维数Ｄ的平面等值线图。通过分析研究，发现所求得的分维数Ｄ的平面等值线图能反映出区域构造的特点，不同计算窗口所求得的Ｄ值不一样，相应的Ｄ值平面等值线图反映出不同深度层次的区域构造格局。利用相同窗口尺寸求得的重磁异常场分维数Ｄ可以进行重磁异常信息复合，本文提出了一种复合方法，并给出了复合结果并作了分析。最后，笔者探讨了区域重磁异常场的分维数的物理意义和这种自仿射分维数大于３的问题。 相似文献
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西天山CuNi-VTiFe复合型矿化镁铁-超镁铁杂岩 ——哈拉达拉岩体成岩成矿背景特殊性讨论 总被引：6，自引：4，他引：2
西天山哈拉达拉镁铁-超镁铁杂岩为一CuNi-VTiFe复合型矿化岩体,主要由橄长岩、橄榄辉长岩、角闪辉长岩、辉长岩和辉绿岩组成。获得岩体中橄榄辉长岩SHRIMP锆石U-Pb年龄为308.8±1.9Ma,辉长岩SHRIMP锆石U-Pb年龄307.3±8.2Ma。岩石具堆晶结构、辉长-辉绿结构,岩体韵律层发育;各类岩石稀土和微量元素配分曲线模式相似,多具Eu,Sr正异常,它们可能为同一岩浆结晶分异演化的产物;Sr-Nd同位素特征(87Sr/86Sr初始比值=0.703913～0.705259,εNd(t)=4.00～8.42)表明原始岩浆来自于亏损地幔源区。推测哈拉达拉岩体形成于后碰撞造山早期伸展环境、叠加近同期地幔柱活动的特殊地质背景中。 相似文献
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运用分形理论对四川攀枝花层状侵入体的韵律层厚度进行分维计算, 并结合计算机模拟手段, 对韵律层理的成因进行了探讨.通过分形计算表明, 攀枝花层状侵入体的韵律层在厚度上具有分形结构, 其分维数介于1.4~1.8之间, 不同级别韵律层的厚度分维数不同, 韵律演化的级别越高, 厚度分维数越大.通过模拟计算的韵律色度分维数与实测韵律层的厚度分维数比较接近, 变化规律也比较相似, 这不仅说明在韵律的演化过程中, 厚度和色率之间有一定的内在联系, 也说明了重力在韵律形成机制中是一个重要的影响因素.地球的重力作用与地球的其他物理化学作用在空间和时间上耦合, 形成了这种具有时空分形结构的韵律现象. 相似文献
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《International Geology Review》2012,54(3):206-242
Two anorthosite massifs in the Eastern Ghats share similar structural constitutions, internal differentiation histories, and overall thermal-tectonic patterns of evolution. The (1) circular to near-circular structural patterns both inside and close-to-border outside of the plutons; (2) the merging of these structures with the straight to gently flowing, essentially unidirectional structural trend of the granulite basement within short distances from the border of the plutons; (3) the increase of strain intensity near the border of the plutons; (4) the small but recognizable differences in the dip of the anorthosite flow layers; and (5) the foliation of the granulites, all are strong indications that these anorthosites were emplaced as syntectonic diapirs. In both massifs, anorthosite is by far the dominant lithology, noritic varieties being subordinate and generally formed as narrow dike-like bodies and pods, pockets, and irregular patches near the border. The striking features of the whole-rock and mineral chemistries of these massifs are increasing Fe, Ti, Mg, P, and REE, and decreasing Si and Al from the leucoanorthosites to the noritic rocks and wide Mg-Fe variation in the pyroxenes, in contrast to a relatively uniform plagioclase composition. These variations may be the result of initial differentiation in a layered complex serving as a precursor to the anorthosites, through modal sorting, rhythmic layering and cryptic changes, and a subsequent mixing of the modally sorted and cryptically enriched layers at different stages of anorthosite diapirism. Diapiraureole structural relationships, petrology, and thermobarometry suggest a moderately steep, counterclockwise cooling and exhumation path for both massifs to the P-T range: 5 to 6 kbar and 600 to 700°C. Such considerations, supplemented by a conductive cooling model for anorthosite emplacement and its subsequent evolution, lead to a branched path as the essential topology of the P-T-time history of the anorthosite-granulite associations of the Eastern Ghats. An important corollary of this inference is that a cycle of prograde and retrograde metamorphism of the aureole rocks—before and after the anorthosite invasion, respectively—is an essential consequence of the anorthosite emplacement. 相似文献
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The Guadalupe igneous complex is one of several late Jurassic,mesozonal plutons in the foothills of the Sierra Nevada. Severallines of evidence suggest that the different rock types, rangingfrom eucrite to leucogranophyre, originated mainly through fractionalcrystallization of a parent basaltic magma. Important differencesbetween this complex and other large differentiated basic intrusionsinclude the presence of steeply inclined but weak layering inthe gabbroic rocks and an abundance of hydrous mafic mineralsrelative to olivine and pyroxene, which are not representedby iron-rich end-members in the granitic differentiates. Chemically,the differentiation trend is marked by a large variation infelsic parameters and only a weak enrichment in iron. This trend,which is similar to that of calc-alkaline suites of orogenicregions, may have been influenced by abnormally high pressuresof water and oxygen for a crystallizing basaltic magma. 相似文献
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SIZE DIFFERENTIATION IN A CROSS-STRATIFIED UNIT 总被引：1，自引：0，他引：1
SUDHIR BASUMALLICK 《Sedimentology》1966,6(1):35-68
Careful sampling of the constituent laminae of cross-stratified units and their subsequent mechanical analyses have revealed a rhythmic pattern of size differentiation. The cross-strata have been analysed in terms of our existing knowledge of the mechanics of layering in granular sediments. The concept of “elementary rhythm-unit” has been introduced and the genesis of a cross-stratified unit has been reviewed in terms of the growth and interplay of the elementary rhythm-unit. 相似文献
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Rhythmic Layering in the Apatite (-Magnetite) Deposit in the Fanshan Complex, North China 总被引：1，自引：0，他引：1
Abstract. The Fanshan complex consists of three (First- to Third-) Phases of intrusion. The First-Phase Intrusive is composed of rhythmic layers. The Fanshan apatite (-magnetite) deposit is situated near the top of no. 6 rhythmic Unit of the First-Phase Intrusive. Two sketch maps were drawn through the deposit along no. 25 cross-cut on 425 mL and no. 1 crosscut on 491 mL in the Fanshan mine. Through this mapping, a small-scaled rhythmic layering (called sub-rhythmic layering) was newly found. The sub-rhythmic layering consists of five typical rocks: biotite clinopyroxenite, biotite rock, biotite-apatite rock, alternation biotite-apatite rock and apatite rock. The thickness of layers varies from four millimeters to several meters. Six units of sub-rhythmic layering were distinguished. Each unit consists of biotite clinopyroxenite (or biotite rock and biotite-apatite rock) layer at the bottom and apatite rock layer at the top.
Major element compositions of biotite and clinopyroxene were analyzed. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*: total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub-rhythmic unit. A general trend, however, through the whole sub-rhythmic layering sequence shows that the both minerals become relatively magnesian upwards. The hypotheses of liquid immiscibili-ty, gravitational settling and magma mixing are against with the results obtained in the present study. This study suggests that the apatite (-magnetite) deposit is formed through fractional crystallization process. 相似文献
Major element compositions of biotite and clinopyroxene were analyzed. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*: total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub-rhythmic unit. A general trend, however, through the whole sub-rhythmic layering sequence shows that the both minerals become relatively magnesian upwards. The hypotheses of liquid immiscibili-ty, gravitational settling and magma mixing are against with the results obtained in the present study. This study suggests that the apatite (-magnetite) deposit is formed through fractional crystallization process. 相似文献