Introduction:Cathodoluminescence (CL) is sensitive to defects and/or impurities in crystals. CL images have been used to observe microstructures within grains to understand mineral growth and diagenetic processes (Götze 2009). It has also been used in structural geology to observe patterns of healed fractures, subgrain boundaries (SGBs), and twins (Shimamoto et al 1991; Hamers et al 2017). We observed deformed quartz phenocrysts with different degrees in mylonitized granite porphyries reported by Kano and Takagi (2013). In CL images of the deformed quartz phenocrysts, some planar deformation features (PDFs) can be observed. In this study, we analyzed the CL images and EBSD maps of the weakly deformed quartz phenocryst to clarify the formation processes of PDFs observed in CL images. In addition, we will evaluate impurity distribution within quartz phenocrysts by EPMA compositional maps and FT-IR H₂O concentration maps.

Results and Discussion:Quartz phenocrysts exhibit an undulose extinction indicative of internal plasticity under the optical microscope. Kernel Average Misorientation (KAM) maps and orientation difference profile normal to the extension direction of an undulose extinction show misorientation angles between two adjacent pixels are less than 2°. SGBs with a misorientation angle of no less than 0.4° can be assigned to almost all the PDFs. In pole figures, the crystallographic axes and planes of quartz are rotated around the c-axis, and the misorientation axes distribute parallel to the c-axis, indicating a dominant prism <a> slip system. Our observations suggest that SGBs under the optical and EBSD observations can be comparable with the PDFs in CL images, implying that the PDFs in CL images can be derived from the accumulation of defects to SGBs. Furthermore, we estimated the stress applied to quartz phenocryst based on the subgrain size piezometer of Goddard et al (2020). Given the misorientation angle of 1°, the subgrain size is 29 µm, and the estimated stress is 14 MPa.

References: Goddard et al (2020) Geophys Res Lett 47:e2020GL090056; Götze (2009) Mineral Mag 73:645–671; Hamers et al (2017) Phys Chem Mineral 44:263–275; Kano and Takagi (2013) Geol Soc Japan 119:776–793; Shimamoto et al (1991) J Struct Geol 13:967–973.

During plastic deformation of quartz under the upper crustal conditions, <a> slip systems are predominantly active, which has been considered to be temperature-dependent (Law 2014). However, based on a detailed textural analysis of CPOs of experimentally and naturally deformed quartz samples, Kilian and Heilbronner (2017) argued that the basal <a> slip system is not the dominant slip system under the upper crustal conditions. To clarify the relative importance of slip systems in quartz, based on optical and EBSD observations, we analyze quartz phenocrysts in deformed granite porphyry samples of different strains reported by Kano and Takagi (2013). The quartz phenocrysts exhibit undulate extinction, commonly elongate and lenticular with different aspect ratios (ARs) (i.e., strain) ranging from 1.2 to 6.3 to identify the dominant active slip system based on misorientation analyses via EBSD data (Lloyd et al. 1997). The misorientation axis of almost all concentrated subparallel to the Y-axis (i.e., rotation axis) of the sample coordinates. Only the phenocryst with AR=1.8 has concentrated in the periphery near the Z-axis of the sample coordinates and also parallel to the [c] axis; the high density distributed around the [c] axis in the crystal coordinates may be twist boundary. Phenocrysts with ARs of 6.3 and 3.7, the misorientation density shows a maximum around the [c] axis, indicative of the activity of prism <a>. Phenocryst with AR of 3.1, the highest density concentration is close to the {m} and perpendicular to the [c] axis, indicative of the activity of basal <a> (+ prism [c]). The phenocryst with AR of 1.6 has distributed two concentrations around the [c] and <a> axes, indicative of twist boundary (basal +basal ) and the activity of prism [c]. Consequently, the dominant slip systems in the quartz phenocrysts are prism <a> and basal <a> (+ prism [c]). The values of the AR of quartz phenocrysts indicative of the activity of prism <a> slip system are higher than those with basal <a> slip system, implying that the CRSS for the former is lower than that for the latter. References: Kano and Takagi (2013) J Geol Soc Japan 119:776. Lloyd et al. (1997) Tectonicphysics 279:55. Kilian and Heilbronner (2017) Solid Earth 8:1095. Law (2014) J Struct Geol 66:129.

Major mass extinctions in the Phanerozoic Eon occurred during abrupt global climate changes accompanied by environmental destruction driven by large volcanic eruptions and projectile impacts. Relationships between land temperature anomalies and terrestrial animal extinctions as well as the difference in response between marine and terrestrial animals to abrupt climate changes in the Phanerozoic have not been quantitatively evaluated. My analyses show that the magnitude of major extinctions in marine invertebrates and that of terrestrial tetrapods correlate well with the coincidental anomaly of global and habitat surface temperatures during biotic crises, respectively, regardless of the difference between warming and cooling (correlation coefficient R = 0.92–0.95). The loss of more than 35 % of marine genera and 60 % of marine species loss corresponding to major mass extinctions so called “big five” correlate with a > 7 °C global cooling and a 7–9 °C global warming for marine animals, and a > 7 °C global cooling and a > ~7 °C global warming for terrestrial tetrapods, accompanied with ± 1 °C error in the temperature anomalies as the global average, although number of terrestrial data is small. These relationships indicate that (i) abrupt changes in climate and environment associated with high energy input by volcanism and impact relate to the magnitude of mass extinctions and (ii) the Anthropogenic future extinction magnitude will not reach the major mass extinction magnitude, when the extinction magnitude parallelly changes with global surface temperature anomaly. In the linear relationship, I found lower tolerance of terrestrial tetrapods than that of marine animals for the same global warming events and a higher sensitivity of marine animals to the same habitat temperature change than terrestrial animals. These phenomena fit to the ongoing extinctions.