Evidence for dendritic crystallization of forsterite olivine during contact metamorphism of siliceous dolostones, Alta stock aureole, Utah
Evidence for dendritic crystallization of forsterite olivine during contact metamorphism of siliceous dolostones, Alta stock aureole, Utah
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硅质白云岩接触变质过程中镁橄榄石树枝状结晶的证据，阿尔塔库存光环，犹他州
DOI：
10.1007/s00410-020-01734-9
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发表时间：
2020
影响因子：
3.5
通讯作者：
Fernandez, Diego P.
中科院分区：
文献类型：
--
作者：
Beno, Carl J.;Bowman, John R.;Loury, Patrick C.;Tapanila, Lorraine M.;Fernandez, Diego P.
对犹他州阿尔塔接触晕中硅质镁橄榄石变质作用过程中产生的镁橄榄石晶体进行了原位研究，并采用晶体分离来限制其晕尺度的结构和形态变化。随着接触面的靠近，镁橄榄石晶体的丰度增加，但平均尺寸减小，这表明更大的动力学影响镁橄榄石成核和生长的内部光环。在方镁石和镁橄榄石区，晶体形态从树枝状到骨架状再到自形状变化很大。镁橄榄石的高度骨架形式保留了晶体学控制的内部支架，折返物和内部空隙边界。结构上更成熟的镁橄榄石晶体的扫描电子显微镜成像揭示了常见的表面特征，如漏斗结构，脊和阶地，特征已链接到火成岩中橄榄石的树枝状结晶。从镁橄榄石带中部到外部的近端元镁橄榄石晶体（> Fo 99）表现出复杂的阴极发光（CL）模式，这可能与微量元素Li，B，P和Ti的颗粒尺度不均匀性有关。这些颗粒尺度的CL分区模式可以与典型的镁橄榄石的晶体学形式。的纹理趋势，形态特征，表面特征和CL模式表明，自形镁橄榄石晶体生长的早期树枝状结晶，漏斗的发展，并填充漏斗再入体的过程。这些结果警告不要将变质镁橄榄石中保存的所有粒度分带剖面解释为简单的核心到边缘的时间序列。考虑到镁橄榄石形态的发展中的枝晶结晶的可能作用，需要解释2-D元素或同位素分区配置文件保存在个人镁橄榄石晶粒。
Forsterite crystals produced during metamorphism of siliceous dolomites in the Alta, Utah contact aureole were investigated in-situ and with crystal separates to constrain their aureole-scale textural and morphological variability. As the contact is approached, forsterite crystals increase in abundance but decrease in average size, suggesting greater kinetic influence on forsterite nucleation and growth in the inner aureole. Crystal morphologies vary widely from dendritic to skeletal to euhedral shapes across both periclase and forsterite zones. Highly skeletal forms of forsterite preserve crystallographically-controlled internal scaffolding, reentrants and internal void boundaries. Scanning electron microscope imaging of texturally more mature forsterite crystals reveals the common occurrence of surface features such as hopper structures, ridges and terraces, features that have been linked to dendritic crystallization of olivine in igneous rocks. Near end-member forsterite crystals (> Fo99) from the middle to outer forsterite zone exhibit complex cathodoluminescence (CL) patterns which can be linked to grain-scale heterogeneities in the trace elements Li, B, P, and Ti. These grain-scale CL zoning patterns can be correlated to crystallographic forms typical of forsterite. The textural trends, morphological characteristics, surface features and CL patterns suggest that euhedral forsterite crystals grew by a process of early dendritic crystallization, hopper development, and infilling of hopper reentrants. These results caution against interpreting all grain-scale zoning profiles preserved in metamorphic forsterites as simple core-to-rim time sequences. Consideration of the possible role of dendritic crystallization in the development of forsterite morphologies is required to interpret 2-D element or isotope zoning profiles preserved in individual forsterite grains.
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影响因子：
2.9
作者：
S. Cook;J. R. Bowman;C. Forster
通讯作者：
C. Forster
镁橄榄石中的CO 2 -H 2 O流体包裹体；
影响因子：
2.1
作者：
Andreas Luettge;P. Metz;J. Walther;E. Althaus;W. Heinrich
通讯作者：
W. Heinrich
犹他州布莱顿四边形地质图
DOI：
10.3133/gq534
发表时间：
1966
期刊：
Geologic Quadrangle
影响因子：
--
作者：
A. A. Baker
通讯作者：
A. A. Baker
影响因子：
2.8
作者：
J. Donovan;T. Tingle
通讯作者：
J. Donovan;T. Tingle
通过熔体包裹体研究得出大西洋中脊下方岩浆房中对流的时间尺度
影响因子：
3.5
作者：
A. Colin;F. Faure;P. Burnard
通讯作者：
P. Burnard