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首页> 外文期刊>Journal of Asian earth sciences >Magma chamber processes and dynamics beneath northwestern Anatolia: Insights from mineral chemistry and crystal size distributions (CSDs) of the Kepsut volcanic complex (NW Turkey)
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Magma chamber processes and dynamics beneath northwestern Anatolia: Insights from mineral chemistry and crystal size distributions (CSDs) of the Kepsut volcanic complex (NW Turkey)

机译：安纳托利亚西北部下方的岩浆腔过程和动力学：从Kepsut火山群（土耳其西北部）的矿物化学和晶体尺寸分布（CSD）得出的见解

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Mineral chemistry, petrography and crystal size distributions of Early Miocene mafic and intermediate lavas from the Kepsut Volcanic Complex (KVC) have been studied to decipher magma chamber processes and dynamics beneath northwestern Anatolia. KVC which is a part of the Western Anatolian Volcanic Province comprises lavas represented by various compositions ranging from basaltic andesite to rhyodacite and associated pyroclastics. Basaltic andesite and andesite lavas of the KVC, the focus of this study, present distinct petrographical features such as three plagioclase generations, patchy zoning, oscillatory reverse zoning, sieve textured crystals and clinopyroxene-mantled amphibole that are clear indicators of disequilibrium conditions in magma chamber(s). Petrography, mineral chemistry and crystal size distribution studies of andesite and basaltic andesite lavas of the KVC indicate that magma evolution occurred in four stages: (I) Near-Equilibrium Stage, (II) Mafic Input Stage, (III) Mixing/Mingling Stage and (IV) Pre-eruption Stage. Thermobarometry calculations indicate that crystallization of andesite and basaltic lavas occurred at similar pressure (mid-to-deep crustal depths, 5-7 kbar) but distinct temperature conditions (920-952 degrees C and 921-1069 degrees C, respectively) suggesting that KVC magmas evolved either in the same or different magma chambers at similar depths and experienced open-system processes. Both of these hypotheses are compatible with multistage evolution of the KVC. Combined petrography, mineral chemistry and geothermometry studies on KVC rocks indicate that mixing/mingling processes and subsequent decompression-driven crystallization were the principal mechanisms for the origin of the textural and mineralogical diversity that is characteristic of KVC lavas. Disequilibrium crystallization was probably caused by the influx of a hotter basaltic magma into crustal magma chambers during the first major period of north-south extension in western Anatolia.
机译：已经研究了从Kepsut火山综合体（KVC）的中新世早期镁铁质和中间熔岩的矿物化学，岩石学和晶体尺寸分布，以破译安纳托利亚西北部下方的岩浆腔过程和动力学。作为西安纳托利亚火山省的一部分的KVC包含熔岩，熔岩具有从玄武岩安山岩到流纹岩的各种成分，以及相关的碎屑岩。这项研究的重点是玄武岩的安山岩和安山岩熔岩，表现出独特的岩相学特征，例如三个斜长石世代，斑片状带状，振荡反向带状，筛网状晶体和斜辉石修饰的角闪石，这些都是岩浆室内不平衡状况的明确指标。 （s）。 KVC的安山岩和玄武质安山岩熔岩的岩石学，矿物化学和晶体尺寸分布研究表明，岩浆演化发生在四个阶段：（I）接近平衡阶段，（II）镁铁质输入阶段，（III）混合/混合阶段和（四）喷发前阶段。热压法计算表明，安山岩和玄武岩熔岩的结晶发生在相似的压力下（地壳深部至深部，5-7 kbar），但温度条件不同（分别为920-952摄氏度和921-1069摄氏度），这表明KVC岩浆在相同或不同的岩浆室内以相似的深度演化，并经历了开放系统过程。这两个假设都与KVC的多阶段演进兼容。对KVC岩石的岩石学，矿物化学和地热学研究相结合，表明混合/混合过程以及随后的减压驱动结晶是形成KVC熔岩特征的组织学和矿物学多样性的主要机制。不平衡结晶可能是由较热的玄武岩浆流入安纳托利亚西部南北向扩展的第一个主要时期进入地壳岩浆室引起的。

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