16:30 〜 19:00
[R12-P-1] （エントリー）変形石英斑晶の形態・格子定向配列から推測した石英すべり系における歪みの影響
キーワード：格子定向配列、石英すべり系、変形石英斑晶
To clarify the relationship between the strain and the activity of slip systems in quartz, we analyzed crystallographic and shape preferred orientation of sheared quartz phenocrysts in a granitic porphyry in the Ryoke belt, Awaji Island, SW Japan. In general, slip systems, i.e., basal <a>, rhomb <a> and prism <a> slip systems,are the active slip systems under the upper crustal condition, and the activity of slip systems has been considered to be temperature-dependent (Passchier and Trouw 2005; Law 2014). It has been proposed that basal and prism may operate readily at lower and higher temperature conditions. However, based on the detailed textural analysis of CPOs of experimentally deformed Black Hills Quartzite, Kilian and Heilbronner (2017) suggested that the texture transition is not as a result of the temperature-dependent activity of different slip systems but as a result of different texture forming processes depending on stress and/or strain. Textures with peripheral [c] axes are often observed in rocks deformed under low-grade conditions cannot attribute to the activity of basal slip system, and proposed oriented nucleation and growth a new process to form textures with peripheral [c] axes. Furthermore, with increasing strain, dislocation glide involving prism and rhomb slip leads to a high density of [c] axes in the center of the pole figure.
In this study, we analyzed the deformed granitic porphyry samples with different strain, which has been reported by Kano and Takagi (2013), and measured the shape preferred orientation of quartz grains by calculating aspect ratio from the long and short axis of grains are those of fitted ellipse to grain shape using ImageJ software to reveal the strain magnitude. Quartz CPOs was measured by U-stage equipped with an optical microscope to infer the operative slip systems. Based on the crystallographic- and shape-preferred orientation of sheared quartz phenocrysts in a granitic porphyry, we will discuss the effect of strain on the activity of slip system in deforming quartz.
References: Kano H, Takagi H (2013) J Geol Soc Japan 119:776–793. Kilian R, Heilbronner R (2017) Solid Earth 8:1095–1117. Law RD (2014) J Struct Geol 66:129–161. Passchier CW, Trouw RAJ (2005) Microtectonics.
In this study, we analyzed the deformed granitic porphyry samples with different strain, which has been reported by Kano and Takagi (2013), and measured the shape preferred orientation of quartz grains by calculating aspect ratio from the long and short axis of grains are those of fitted ellipse to grain shape using ImageJ software to reveal the strain magnitude. Quartz CPOs was measured by U-stage equipped with an optical microscope to infer the operative slip systems. Based on the crystallographic- and shape-preferred orientation of sheared quartz phenocrysts in a granitic porphyry, we will discuss the effect of strain on the activity of slip system in deforming quartz.
References: Kano H, Takagi H (2013) J Geol Soc Japan 119:776–793. Kilian R, Heilbronner R (2017) Solid Earth 8:1095–1117. Law RD (2014) J Struct Geol 66:129–161. Passchier CW, Trouw RAJ (2005) Microtectonics.