دورية أكاديمية
Superheated melts in hypervelocity meteorite impact craters: Evidence from terrestrial craters
| العنوان: | Superheated melts in hypervelocity meteorite impact craters: Evidence from terrestrial craters |
|---|---|
| المؤلفون: | Chinchalkar, Neeraja |
| المصدر: | Electronic Thesis and Dissertation Repository |
| بيانات النشر: | Scholarship@Western |
| سنة النشر: | 2023 |
| المجموعة: | The University of Western Ontario: Scholarship@Western |
| مصطلحات موضوعية: | Meteorite impact crater, impact melting, zircons, West Clearwater Lake impact structure, Mistastin Lake impact structure, Geochemistry, Geology, Mineral Physics |
| الوصف: | Impact melts physically and texturally resemble endogenic igneous melts but are known to be initially superheated. However, the exact amount of superheating and, therefore, the temperatures experienced by superheated impact melts are not very well constrained. Zircon is a refractory mineral that can survive high pressure-temperature events and has been known to persist even in the extreme conditions of impact events. Additionally, zircon (ZrSiO4) dissociates to zirconia (ZrO2) and silica (SiO2) at temperatures > ~1670 ℃, and the pressure-temperature phase relationships of zircon, zirconia, and silica have been well studied. Zircons in different types of impactites from the West Clearwater Lake impact structure were investigated using various microanalytical techniques to: (1) identify the presence of crystallographic deformation; (2) to assess the orientation relationships arising from polymorphic transformations of high pressure or high temperature phases using a phase heritage approach, and (3) to constrain initial pressure-temperature conditions with the help of phase relationships. We documented evidence for superheating > 2370 ℃ in an impact glass sample, shock pressures of >30 GPa in some impactites, and observed a variety of microstructures ranging from fully dissociated and granular zircons to undeformed zircons in all impactite samples. Our results also demonstrate that impact melt evolution is complex and the evidence for superheating in zircons appears to be differentially preserved in different impactite settings. Furthermore, we also investigated the variation in textures and geochemistry of a thick impact melt deposit (Discovery Hill) at the Mistastin Lake impact structure, which was recently shown to contain evidence for superheating in excess of 2370 ℃. It is proposed that the textures seen in this melt rock are a result of a complex cooling history governed by the initially superheated melt that interacted with cooler country rock. Because such textures are analogous to those seen in ... |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | English |
| العلاقة: | https://ir.lib.uwo.ca/etd/9744Test; https://ir.lib.uwo.ca/context/etd/article/12544/viewcontent/Thesis_V2_AUG30.pdfTest; https://ir.lib.uwo.ca/context/etd/article/12544/filename/0/type/additional/viewcontent/Supp_Geochem_Tables.xlsxTest |
| الإتاحة: | https://ir.lib.uwo.ca/etd/9744Test https://ir.lib.uwo.ca/context/etd/article/12544/viewcontent/Thesis_V2_AUG30.pdfTest https://ir.lib.uwo.ca/context/etd/article/12544/filename/0/type/additional/viewcontent/Supp_Geochem_Tables.xlsxTest |
| حقوق: | http://creativecommons.org/licenses/by/4.0Test/ |
| رقم الانضمام: | edsbas.6A2ED1DC |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |