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福建漳州牛头山火山地质公园火山喷发层序及岩相 总被引：3，自引：1，他引：3
牛头山火山地质公园位于风景壮观秀丽的闽南漳州市海滨，构造位置处于平潭一东山北东向断裂带中段，火山口坐落在龙海市隆教乡白塘村附近，涨潮时古火山口部分被海水淹没成为孤立于海中的小岛，退潮时，火山口全貌再露海面，火山口附近有一深槽（凹地），直径约8m，低于周围岩石3m，火山岩地层为新第三纪佛昙组上段玄武岩，根据岩性分布特征及岩石结构构造和岩层的产状等。可划分为喷溢相和火山颈相，是省内保存较完好的新生代古火山机构。 相似文献
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野外地质调查发现,扬子西缘昭觉—美姑一带存在多处峨眉山玄武岩组古火山机构,为研究其火山喷发旋回与方式提供了良好窗口。古火山机构的岩石类型主要由巨厚玄武岩以及少量的火山碎屑岩和火山碎屑熔岩组成,且均具火山颈爆发相、溢流相和火山洼地相堆积构造特征。系统的地质剖面研究表明,峨眉山玄武岩组存在3次快速喷发亚旋回及25个火山韵律,亚旋回之间不存在火山间歇期。其中,第一亚旋回和第三亚旋回的喷发方式均以爆发相与溢流相为主,而第二亚旋回则以溢流相为主。峨眉山玄武岩组古火山机构的系统厘定和研究,揭示了峨眉山大火成岩省的火山喷发方式和旋回韵律特征,为研究与峨眉山玄武岩组相关的成矿成藏作用提供了重要地层资料。 相似文献
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扬子地台西缘的海相火山央归纳为５种组合１７种构造一岩石亚组合。其中最佳含矿组合为细碧角斑岩组织、玄武－流纹岩双峰组合和均一玄武岩组合等。铜多金属矿床的产出及规模受火山岩建造特征、火山岩时代和碱度，以及火山喷发旋回和古火山机构等联合控制。 相似文献
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老爷庙-额仁山一带发育3套性质不同的火山岩，通过对其岩石组合、岩相、古火山机构特征的详细观察及岩石学、岩石化学、地球化学的研究，晚泥盆世老爷庙组火山岩为玄武岩-安山岩组合，发育盾状和层状火山，属海相环境，为板块消减带岛弧型高铝玄武岩；晚石炭世-早二叠世哈尔加乌组火山岩为陆相火山岩，岩石组合为安山岩．英安岩-流纹岩，以爆发相为主，常形成破火山及锥状火山机构，为陆-陆碰撞造山期火山岩；早二叠世中晚期卡拉岗组火山岩为一套以酸性为主的陆相火山岩，喷溢相发育，常形成穹状古火山机构，岩石组合为英安岩-流纹岩，为造山期弛张期火山岩，3套火山岩为板块不同阶段的火山岩，从老爷庙组火山岩→哈尔加乌组火山岩→拉岗组火山岩，岩石向酸性演化，地壳成熟度愈来愈高，南混合壳转化为陆壳． 相似文献
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康滇裂谷带火山活动及其碱性（钠质）火山岩系特征 总被引：2，自引：1，他引：2
元古代，夹持于现今安宁河－元谋深断裂与小江深断裂之间的地区，是扬子古大陆的边缘裂谷，本文以“康滇裂谷带”命名。研究结果表明，该区广泛发育的元石代碱性火山岩系列及细碧－角斑岩类火山岩组合，是裂谷火山活动的产物，火山活动时限１９５０－９００Ｍａ，可划分为大红山群及昆阳群两个火山旋回。火山岩系多属碱性玄武岩系列，火山活动的中晚期，分异出少量亚碱性拉斑紊武岩系列和高铝玄武岩系列。裂谷带火山喷发区地壳厚度１ 相似文献
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赣南-粤北中生代晚期火山旋回的划分 总被引：6，自引：3，他引：3
根据地层的接触关系、岩石组合、化石组合、同位素年龄及构造特征,赣南－粤北中生代晚期火山活动,可划分出余田、莲花寨、版石和南雄四个火山旋回。余田火山旋回发育于中侏罗世,由玄武岩－流纹岩组成“双峰式”岩石组合;莲花寨火山旋回发育于晚侏罗世,由流纹岩组成“单峰式”岩石组合;版石火山旋回发育于早白垩世晚期－晚白垩世早期,岩石组合较复杂,既有由流纹岩或玄武岩组成的“单峰式”岩石组合,也有由少量玄武岩和大量流 相似文献
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火山岩作为特殊的油气储集岩类型,在国内外均有成功的勘探和开发实例。然而因其规模和储量相对较小,储集空间和成藏系统较为复杂,研究工作起步较晚。鉴于前人研究多依赖于钻井岩芯描述和测井数据分析,为了获得岩石孔隙和各类裂缝在古火山机构中的空间分布规律,本文对福建漳州牛头山玄武质火山岩进行了野外调查和岩石物性分析。牛头山古火山历经四期喷发,地表可见四层喷溢相玄武岩层和两处火山颈相岩石出露。喷溢相玄武质火山岩的孔隙度变化较大,从5.34%到23.73%间不等,但渗透率均较低（平均值为0.173×10-3μm2）。火山机构中节理和裂缝较为发育,除火山颈相的柱状节理、火山喷溢相的爆炸缝、冷凝节理外,熔岩/下伏地层接触热变质成因的高孔带、幔源包体裂缝和爆炸孔以及后期形成的构造裂缝、风化破碎带等均有着重要的意义,这些面型单元构成了贯通整个火山机构的空间网络,使古火山机构的储集潜力不容忽视。 相似文献
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山东中生代橄榄安粗岩系火山岩的地质,地球化学… 总被引：15，自引：0，他引：15
山东中生代橄榄安粗岩系火山岩订分布在沂沭断裂及其两侧的断陷型陆相火山盆地，为早白垩世火山活动的产物。Ｒｂ－Ｓｒ全岩等时年龄变化于１１１．４￣１１９．６Ｍａ，岩石组合主要为粗面玄武岩－橄榄安粗岩－安粗岩－粗面岩。 相似文献
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格吉格音乌拉火山机构主要由集块岩,角砾集块熔岩和碱性橄榄玄武岩组成。玄武岩中含有二辉橄榄岩包体,岩石属大陆内部碱性玄武岩系列。玄武岩层平履于中新统通古尔组之上,是阿巴嘎玄武岩底部层位。玄武岩全岩钾－氩稀释法同位素年龄１２．９９Ｍａ。综合分析认为：阿巴嘎玄武岩早期喷发活动最晚始于上新世。 相似文献
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宁远－道县地区中生代玄武岩中辉长岩包体的岩石化学－地球化学特征表明，辉长岩包体为钙碱性玄武岩系列，形成于活动大陆边缘火山孤环境，辉长碉的形成，侵位、与菲律宾板块自中生代以来向中国大陆俯冲作用有关。 相似文献
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新疆某地红宝石和蓝宝石矿物学研究 总被引：1，自引：0，他引：1
本文系统地研究了新疆某地红宝石和蓝宝石矿床,查明该矿床中红宝石和蓝宝石的粒度、形态、双晶、裂纹,包裹体形态和成分,硬度、密度、多色性、吸收性、Ne和No值,晶胞参数及化学成分等特征,从而为该类矿床的开发利用提供了重要信息。同时,根据这些宝石的物理性质和化学成分上的区别,进一步探讨了呈色机理。 相似文献
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天然红宝石和蓝宝石的包裹体中常见典型的含水矿物包裹体,这些含水矿物包裹体容易受外界环境升温而发生改变。微量含水矿物包裹体变化会对红宝石和蓝宝石的物理和化学性质产生明显影响,该性质为宝石热处理的鉴定提供了检测思路。本文采集了天然红宝石和蓝宝石样品,用显微镜放大观察包裹体特征,结合红外光谱与显微共焦激光拉曼光谱测试研究了含水矿物包裹体的特征。结果表明:天然红宝石和蓝宝石样品中含水矿物包裹体的外观轮廓清晰,晶形完整;红外光谱在2000～3700cm~(-1)附近显示出2105～2110cm~(-1)和1977～1985cm~(-1)硬水铝石和3619cm~(-1)和3696cm~(-1)高岭石等水(H_2O或—OH等)的特征吸收峰;拉曼光谱中可见角闪石、云母、磷灰石和长石等结晶度较好的典型含水矿物包裹体的特征拉曼位移。该系列特征揭示了红宝石和蓝宝石样品中含有水的特征,可作为红宝石和蓝宝石天然成因且未经过热处理的鉴定依据。 相似文献
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Barrington shield volcano was active for 55 million years, based on basalt K–Ar and zircon fission track dating. Activity in the northeast, at 59 Ma, preceded more substantial activity between 55 and 51 Ma and more limited activity on western and southern flanks after 45 Ma. Eruptions brought up megacrystic gemstones (ruby, sapphire and zircon) throughout the volcanism, particularly during quieter eruptive periods. Zircon fission track dating (thermal reset ages) indicates gem‐bearing eruptions at 57, 43, 38, 28 and 4–5 Ma, while U–Pb isotope SHRIMP dating suggests two main periods of zircon crystallisation between 60 and 50 Ma and 46–45 Ma. Zircons show growth and sector twinning typical of magmatic crystallisation and include low‐U, moderate‐U and high‐U types. The 46 Ma high‐U zircons exhibit trace and rare‐earth element patterns that approach those of zircon inclusions in sapphires and may mark a sapphire formation time at Barrington. Two Barrington basaltic episodes include primary lavas with trace‐element signatures suggesting amphibole/apatite‐enriched lithospheric mantle sources. Other basalts less‐enriched in Th, Sr, P and light rare‐earth elements have trace‐element ratios that overlap those of HIMU‐related South Tasman basalts. Zircon and sapphire formation is attributed to crystallisation from minor felsic melts derived by incipient melting of amphibole‐enriched mantle during lesser thermal activity. Ruby from Barrington volcano is a metamorphic type, and a metamorphic/metasomatic origin associated with basement ultramafic bodies is favoured. Migratory plate/plume paths constructed through Barrington basaltic episodes intersect approximately 80% of dated Palaeogene basaltic activity (65–30 Ma) along the Tasman margin (27–37°S) supporting a migratory plume‐linked origin. Neogene Barrington activity dwindled to sporadic gem‐bearing eruptions, the last possibly marking a minor plume trace. The present subdued thermal profile in northeastern New South Wales mantle suggests future Barrington activity will be minimal. 相似文献
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Rubies and sapphires are of both scientific and commercial interest. These gemstones are corundum colored by transition elements within the alumina crystal lattice: Cr3+ yields red in ruby and Fe2+, Fe3+, and Ti4+ ionic interactions color sapphires. A minor ion, V3+ induces slate to purple colors and color change in some sapphires, but its role in coloring rubies remains enigmatic. Trace element and oxygen isotope composition provide genetic signatures for natural corundum and assist geographic typing. Here, we show that V can dominate chromophore contents in Mogok ruby suites. This raises implications for their color quality, enhancement treatments, geographic origin, exploration and exploitation and their comparison with rubies elsewhere. Precise LA-ICP-MS analysis of ruby and sapphire from Mogok placer and in situ deposits reveal that V can exceed 5,000 ppm, giving V/Cr, V/Fe and V/Ti ratios up to 26, 78, and 97 respectively. Such values significantly exceed those found elsewhere suggesting a localized geological control on V-rich ruby distribution. Our results demonstrate that detailed geochemical studies of ruby suites reveal that V is a potential ruby tracer, encourage comparisons of V/Cr-variation between ruby suites and widen the scope for geographic typing and genesis of ruby. This will allow more precise comparison of Asian and other ruby fields and assist confirmation of Mogok sources for rubies in historical and contemporary gems and jewelry. 相似文献
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Many sapphire and ruby occurrences are spatially linked with orogenic belts such as the Pan-African Orogen, the Himalayas, and regions of active or former subduction along the western margin of the Pacific Ocean. These gemstones have oxygen isotope compositions (δ18O) that span >45‰, reflecting the wide range of environments and conditions involved in corundum (Al2O3) formation. We compiled a global data base of sapphire and ruby δ18O, from which the following major groups of gemstones emerge: a dominant population of sapphires with δ18O centred around 5.5‰ (the mantle value) that is spatially related to regions of former subduction; a lesser population of sapphires and rubies with slightly higher δ18O that are associated with skarn and pegmatite; rubies with relatively low δ18O of 0‰–7‰ that occur in hydrothermally altered ultramafic metamorphic rocks in collision zones; and rubies with high δ18O of 14‰–25‰ that are found, almost exclusively, in Himalayan marble. The spatial distribution of the δ18O groups relative to plate boundaries provides insight into the two major periods of continental collision involved in sapphire and ruby formation: the Ediacaran collision of East and West Gondwana (the East African Orogeny) and the Cenozoic collision of India and Asia. 相似文献