Boundary Layer Crystallization in a Basaltic Magma Chamber: Evidence from Rishiri Volcano, Northern Japan
Boundary Layer Crystallization in a Basaltic Magma Chamber: Evidence from Rishiri Volcano, Northern Japan
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DOI：
10.1093/petroj/39.9.1619
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发表时间：
1998-09
影响因子：
3.9
通讯作者：
T. Kuritani
中科院分区：
文献类型：
--
作者：
T. Kuritani
玄武质岩浆的糊状边界层过程的演化简介在岩浆房中记录的碱性玄武岩（Kutsugata岩浆房的演化是主要的岩石熔岩）从利尻火山，北方日本，分区的基础上，并已被广泛研究。斜长石斑晶的实验模式和它们的空间分布以及研究熔岩冷却的理论研究。斜岩斑晶具有复杂的岩浆房分带模式，表明岩浆可分为四种类型。第一类是一个极端的腔室，通过形成糊状的富An核（An 71 -90）而固化，该核通常被侵蚀并填充有由晶体和间隙熔体组成的ary层，沿沿着钠质斜长石。第2类具有被室壁的钙质包围的富Ab核（例如Brandeis & Jaupart，1986;部分溶解的Turner地幔特征。类型3的特征在于等人，1986; Marsh，1988; Tait & Jaupart，1992）。层状火成杂岩（例如，莫尔斯，1969年;雪莉，1987年;一个富Ab核，通常被一个缓变带的McBirney，1996年）提供了有用的信息，如何轻微钙质地幔。第四类为富Ab核，无钙基性岩浆房演化固结，但具幔源性质。第1类斜长石的富An核太钙化，不能提供太多关于从任何全岩室所代表的液体中结晶的瞬时状态的见解，因为这些侵入体在长凝固时间内发生的Kutsugata岩浆的估计温度下整合了过程成分（McBirney & system.据推测，富An核形成于一个Noyes，1979; Tait，1988）。火山产物，如沿岩浆房壁沿着的糊状边界层，在那里熔岩流和火山灰沉积，可以取样在岩浆中是相对冷的，富含水，因为一个显着的岩浆房的瞬态状态。有一些橄榄石分馏，可能是因为沿着这条路线沿着增加了水研究（Tait，1988年; de Silva，从1989年的冷冻边缘和/或地下水中排出; Nakada等人，1994年）。这些研究集中在周围的地壳。火山产物中的2-4型斜长石晶群和斑晶中的富Ab核被解释为在主岩浆中结晶，该晶体形成于储层的糊状边界层体中。第2、3类富Ab核在岩浆演化中起主导作用，岩浆通过对流作用进入糊状层。储层的时空变化。然而，这些研究大多是对玄武质熔岩流岩浆中斜长石斑晶分带模式的研究，在物理性质上存在显著差异，对镁铁质岩浆房的演化提供了有用的信息。岩浆房与镁铁质岩浆房之间的化学特征。本文研究了日本北方利尻火山碱性玄武岩（Kutsugata熔岩）的岩浆演化。根据全岩化学特征，将库茨加塔熔岩分为三个熔岩流
The evolution of basaltic magma by mushy boundary layer processes INTRODUCTION in a magma chamber is documented for an alkali basalt (Kutsugata The evolution of magma chambers is of major petrologic lava) from Rishiri Volcano, northern Japan, on the basis of zoning interest and has been studied extensively. Experimental patterns of plagioclase phenocrysts and their spatial distribution in and theoretical studies that have investigated the cooling the lava. Plagioclase phenocrysts with complex zoning patterns can of magma chambers have demonstrated that a magma be divided into four types. Type 1 is characterized by an extremely chamber solidifies through formation of a mushy boundAn-rich core (An71–90), which is commonly corroded and filled with ary layer composed of crystals and interstitial melt along sodic plagioclase. Type 2 has an Ab-rich core surrounded by a calcic the chamber walls (e.g. Brandeis & Jaupart, 1986; Turner mantle characteristic of partial dissolution. Type 3 is characterized by et al., 1986; Marsh, 1988; Tait & Jaupart, 1992). Layered igneous complexes (e.g. Morse, 1969; Shirley, 1987; an Ab-rich core that is commonly surrounded by a reversely zoned McBirney, 1996) provide useful information on how slightly calcic mantle. Type 4 has an Ab-rich core without a calcic mafic magma chambers evolve and consolidate, but they mantle. The An-rich cores of the Type 1 plagioclase are too calcic do not offer much insight into the instantaneous state of to have crystallized from a liquid represented by any whole-rock a chamber, because those intrusions integrate processes composition at the estimated temperatures of the Kutsugata magma that occurred over long solidification times (McBirney & system. The An-rich cores are inferred to have been formed in a Noyes, 1979; Tait, 1988). Volcanic products, such as mushy boundary layer along the wall of a magma chamber, where lava flows and tephra deposits, can sample the inthe magma was relatively cool and rich in water because of significant stantaneous state of a magma chamber. There are a few olivine fractionation and possibly because of addition of water studies along this line of approach (Tait, 1988; de Silva, expelled from the chilled margin and/or groundwater from the 1989; Nakada et al., 1994). These studies focused on surrounding crust. The Ab-rich cores of Types 2–4 plagioclase crystal aggregates in volcanic products and concluded phenocrysts are interpreted to have crystallized in the main magma that the crystal formation in a mushy boundary layer body of the reservoir. The Types 2 and 3 Ab-rich cores were brought plays a dominant role in magmatic evolution in a magma to the mushy layer by convection. The temporal and spatial variations reservoir. However, these studies were mostly on silicic of zoning patterns of plagioclase phenocrysts in basaltic lava flows magmas and there are significant differences in physical give useful information on the evolution of mafic magma chambers. and chemical features between silicic and mafic magma chambers. In this paper, the magmatic evolution of an alkali basalt (Kutsugata lava) from Rishiri Volcano, northern Japan, is studied. The Kutsugata lava is divided into three lava flows on the basis of whole-rock chemical