| 论南京娘娘山碱性岩浆房的梯度及基成因机制 |
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| 引用本文： | 陶奎元,薛怀民.论南京娘娘山碱性岩浆房的梯度及基成因机制[J].岩石矿物学杂志,1989,8(4):289-299. |
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| 作者姓名： | 陶奎元 薛怀民 |
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| 摘 要： | 本文详细研究了娘娘山碱性火山杂岩体中矿物斑晶和化学成分的变化情况，发现它们
定位前在岩浆房中就存在着物质成分的梯度和分带性。提出并论证矿物的分离结晶是该岩浆房中
梯度形成的主要机制，但由对流所控制的热重力扩散作用对岩浆房中成分梯度的形成也具一定的
影响。
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| 关 键 词： | 岩浆房 成分梯度 分离结晶 |
The Characteristics and Origin of Gradient in Niangniangshaa Alkaline Magma Chamber |
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| Abstract: | Niangniangshan alkaline volcanic complex developed in the late stage of
Mesozoic volcanic activities in Ningwu volcanic structural depression was
special type of rock association, In general, they were characterized by
rich-potassium, LREE and other hygromagmaphile elements in geochemistry,
This alkaline volcanic complex can be subdivided into two parts, belonging
to the products of two sub-cycles of volcanic activities respectively, The
lower part of this rock association bears pseudoleucite, characteristic mine-
ra.l rich in potassium, and the upper part of this association bears hattyne,
characteristic mineral rich in sodium, In this paper, we suggest that they
came from a same magma chamber with compositional gradients by means
of the petrologic, petrochemistry and trace elements geochemistry study.
The crystal fractionation accounts for coming to compositional gradient in
the chamber, but thermogravitational effect may play some role during
magma differentiation, particularly for the generation of capping layer
rich in volatile components, The mass balance calculations quantitatively
modeled the crystal fractionation process in the chamber, and confirmed
the results observed. That is to say, as a mineral of the lower density,
leucite phenocrysts accumulated in the top part of the chamber, whereas
those phenocrysts having higher density (such as pyroxene, hatiyne, plagi-
oclase) settled downward in the chamber. |
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