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Zoned quartz phenocrysts in supercooled melt inclusions in granulites from continental collision orogens
Island Arc ( IF 1.5 ) Pub Date : 2020-11-20 , DOI: 10.1111/iar.12374
Yoshikuni Hiroi 1, 2 , Tomokazu Hokada 2, 3 , Masahiro Kayama 4 , Akira Miyake 5 , Tatsuro Adachi 6 , Bernard Prame 7 , Keerthi Perera 8 , Madhusoodhan Satish‐Kumar 9 , Yasuhito Osanai 10 , Yoichi Motoyoshi 2 , David J. Ellis 11 , Kazuyuki Shiraishi 2
Affiliation  

Felsite inclusions (FIs) in granulite garnets from continental collision orogens are supercooled felsic melt inclusions. Not only do these represent non‐equilibrium textures, such as dendritic and spherulitic crystals of quartz and other minerals, but the porphyritic texture is that of hypabyssal and volcanic rocks. This paper presents representative zoned quartz phenocryst‐bearing FIs in various granulites from the Highland Complex in central Sri Lanka, the Lützow‐Holm Complex in East Antarctica, the Grenville Province in southeastern Canada, and the Kerala Khondalite Belt in southern India. Quartz phenocrysts show simple and definite cathodoluminescence (CL) zoning with euhedral bright cores and dark rims and overgrowths. Euhedral quartz never develops in subsolidus metamorphic rocks except for vein quartz, and is characteristic of growth in a melt phase. Groundmass quartz surrounding quartz phenocrysts within the FIs is always dark in CL, whereas matrix quartz outside garnet and single‐grain inclusion quartz in garnet are usually brighter than the cores of quartz phenocrysts. The close relationship between violet CL emission intensity and Ti content of quartz indicates different growth temperatures in harmony with the inferred crystallization sequence. The preservation of CL growth zoning in quartz phenocrysts and fine non‐equilibrium textures imply that the cooling rates of some granulites are 1 to 2 orders of magnitude faster than so far presumed.

中文翻译:

来自大陆碰撞造山带的颗粒中过冷熔体包裹体中的带区带石英现象

来自大陆碰撞造山带的粒状石榴石中的长铁质包裹体(FIs)是过冷的长英质熔体包裹体。这些不仅代表不平衡的质地,例如石英和其他矿物的树枝状和球状晶体,而且斑状质地也包括下伏和火山岩。本文介绍了斯里兰卡中部的高地综合体,南极东部的吕茨霍姆综合体,加拿大东南部的格伦维尔省以及印度南部的喀拉拉邦本多岩带中各种花岗岩中具有代表性的带石英斑晶的FIs。石英隐晶石显示简单而明确的阴极发光(CL)分区,具有明亮的正核心,深色边缘和过度生长。除了脉状石英外,亚固相变质岩中从未发育出全反射石英,并且是熔融相中生长的特征。在FI中,位于FI内的石英质表观晶的地基石英总是较暗,而石榴石外的基质石英和石榴石中的单粒夹杂物石英通常比石英表观晶核更亮。紫罗兰色CL发射强度与石英Ti含量之间的密切关系表明不同的生长温度与推断的结晶顺序一致。石英表晶和微细非平衡织构中CL增长区的保留意味着某些颗粒的冷却速度比目前的估计要快1至2个数量级。石榴石外的基质石英和石榴石中的单粒夹杂物石英通常比石英隐晶石的芯亮。紫罗兰色CL发射强度与石英Ti含量之间的密切关系表明不同的生长温度与推断的结晶顺序一致。石英表晶和微细非平衡织构中CL增长区的保留意味着某些颗粒的冷却速度比目前的估计要快1至2个数量级。石榴石外的基质石英和石榴石中的单粒夹杂物石英通常比石英隐晶石的芯亮。紫罗兰色CL发射强度与石英Ti含量之间的密切关系表明不同的生长温度与推断的结晶顺序一致。石英表晶和微细非平衡织构中CL增长区的保留意味着某些颗粒的冷却速度比目前的估计要快1至2个数量级。
更新日期:2020-12-02
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