| 内蒙古正镶白旗碎斑熔岩岩石学特征及其岩相划分 |
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| 引用本文： | 赖绍聪,徐海江.内蒙古正镶白旗碎斑熔岩岩石学特征及其岩相划分[J].岩石学报,1990,6(1):56-65. |
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| 作者姓名： | 赖绍聪 徐海江 |
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| 作者单位： | 华东地质学院,华东地质学院 江西抚州 344000,江西抚州 344000 |
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| 摘 要： | 白旗碎斑熔岩为不规则穹状体,可分为边缘玻质碎斑熔岩、过渡霏细碎斑熔岩、中心粒状碎斑熔岩和根部花岗斑岩四个岩性带。从玻质碎斑熔岩到粒状碎斑熔岩,斑晶碎裂度逐渐减弱,珠边结构在粒状碎斑熔岩中最发育,根部花岗斑岩与正常次火山岩相近。碎斑熔岩中钾长石有序度低,指示了岩石高温成因特征。白旌碎斑熔岩属太平洋岩系钙碱质系列,原始岩浆由来源于上地幔和下地壳熔体的混熔作用形成。
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| 关 键 词： | 碎斑熔岩 岩石特征 化学成分 成因机制 内蒙古 |
THE LITHOLOGIC FEATURE AND GENESIS OF THE PORPHYROCLASTIC LAVA IN BAIQI AREA NEIMONGGOL |
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| Lai Shaocong Xu Haijiang.THE LITHOLOGIC FEATURE AND GENESIS OF THE PORPHYROCLASTIC LAVA IN BAIQI AREA NEIMONGGOL[J].Acta Petrologica Sinica,1990,6(1):56-65. |
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| Authors: | Lai Shaocong Xu Haijiang |
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| Abstract: | The main rock type in the Mesozoic volcanic basin in Baiqi area, Neimonggol is a special volcanic rock, the porphyroclastic lava. It is characterized by porphyroclastic texture for phenoerysts, poikilitic texture of pearl margin and vitric-felsitic-microgranular texture for matrix. Its lithologic feature is very similar to the porphyroclastic lava in south-east coastal part of ahina.
All field observations indicate that the porphyroclastic lava body in Baiqi area is dome-like and formed on the ground. From outer part to the inner part or from the upper part to deep one, the variation in petrology should be. vitric porphyroclastic lava (margin part), felsitic porphyroclastic lava (transition part) granulitic porphyroclastic lava (central part), and granite porphyry (root part). They are of gradual modification. From vitric porphyroclastic lava to granulitic porphyroclastic lava, the breaking degree of the phenocrysts decreases, The poikilitic texture of pearl margin is well developed in the granulitic porphyroclastic lava. The granite porphyry (root part of the body) is similar to the normal subvolcanic rock. The potash feldspars in the Baiqi Complex body are of lower ordering degree. They are chiefly low sanidine and high orthoclase. It indicates that the rock formed at high temperature. In the same way, the ordering degree of potash feldspar and plagioclass increases from the margin to root of the body. The porphyroclastic lava in Baiqi area belongs to the Pacific calc-alkaline rock series with chemical character of volcanic rocks in orogenic belt.Its original magma is chiefly from the mixed melting of upper mantle and deep crust.
The porphyroclastic lava body in Baiqi area is of typical facies model. It consists of flow lava facies (margin)-volcano extrusion facies (central)-subvolcanic facies (root). This is a complex body of "co-existing multiple facies". |
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| Keywords: | Porphyroclastic lava lithologic feature Chemical composition Genesis Neimonggol |
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