UNLV Theses, Dissertations, Professional Papers, and Capstones 12-15-2019 Examination of Maskelynite through Static Recompression and Dynamic Compression Justin James Reppart Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Geology Commons, and the Geophysics and Seismology Commons Repository Citation Reppart, Justin James, "Examination of Maskelynite through Static Recompression and Dynamic Compression" (2019). UNLV Theses, Dissertations, Professional Papers, and Capstones. 3837. http://dx.doi.org/10.34917/18608758 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. EXAMINATION OF MASKELYNITE THROUGH STATIC RECOMPRESSION AND DYNAMIC COMPRESSION By Justin J. Reppart Bachelor of Science - Geology University of Nevada, Las Vegas 2015 A thesis submitted in partial fulfillment of the requirements for the Master of Science - Geoscience Department of Geoscience College of Sciences The Graduate College University of Nevada, Las Vegas December 2019 Thesis Approval The Graduate College The University of Nevada, Las Vegas December 4, 2019 This thesis prepared by Justin J. Reppart entitled Examination of Maskelynite through Static Recompression and Dynamic Compression is approved in partial fulfillment of the requirements for the degree of Master of Science - Geoscience Department of Geoscience Oliver Tschauner, Ph.D. Kathryn Hausbeck Korgan, Ph.D. Examination Committee Chair Graduate College Dean Arya Udry, Ph.D. Examination Committee Member Shichun Huang, Ph.D. Examination Committee Member Paul Forster, Ph.D. Graduate College Faculty Representative ii Abstract This is an experimental study that aims to clarify the possible formation mechanisms of maskelynite. Maskelynite is a diaplectic glass, that forms during shock compression of feldspar far below the melting point, and without fusion. Maskelynite also paramorphises precursor feldspar grains. Maskelynite is an important probe of shock-pressures at terrestrial impact sites and in many meteorites. Two mechanisms of formation of maskelynite are examined here: 1) maskelynite is result of a pressure-induced amorphization of feldspar compressed beyond its mechanical stability where the formation of thermodynamically stable phases is kinetically inhibited [1, 2]. 2) Feldspar transforms upon dynamic compression into a high-pressure polymorph. Upon release from the peak shock pressure, this crystalline polymorph transforms back either into a dense glass or a highly disordered solid that appears amorphous in common probes (optical microscope, optical spectroscopy, diffraction). The latter scenario avails for diaplectic silica that formed in shock-experiments on quartz. Upon static compression of synthetic diaplectic silica at 300 K the material resumes the crystalline structure of stishovite [3], a high- pressure polymorph of silica which has also been observed in situ during shock compression of fused quartz [4]. Hence, the second scenario implies a memory effect of the high-pressure crystalline structure in the diaplectic glass. In the present study, we test this hypothesis for maskelynite by a) X-ray diffraction of maskelynite similar to the study of diaplectic silica in [3], b) synchrotron X-ray diffraction analysis of synthetic maskelynite at ambient pressure, both with the goal of identifying possible crystalline states. If no crystalline state is observed, the second proposed mechanism of maskelynite formation is not supported and the first mechanism appears more likely. iii In the static compression experiment I find indications of a change in middle-range order of maskelynite but no transition to long-range crystalline order upon compression to 19 GPa. In the shock-recovered maskelynite I observe crystalline material, even in material recovered from 38.5 GPa. The crystalline material is disseminated in an amorphous matrix and has feldspar-like structure rather than a structure related to a high-pressure polymorph of feldspar. Hence this crystalline material is remnant crystalline feldspar rather than a phase that formed upon shock- compression. iv Acknowledgements UNLV HiPSEC: This research was sponsored (or sponsored in part) by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement #DE-NA0001982. HPCAT: Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357. Jacobs Engineering: Parts of this work was aided by Jacobs Engineering and NASA’s Johnson Space Center. In specific I would like to thank Lisa Danielson, Richard Rowland II, Mark Cintala, Frank Cardenas, Roland Montes and Kathleen Vander Kaaden. I would also like to thank my advisor, Dr. Oliver Tschauner and the entire UNLV Department of Geoscience for their assistance and guidance during my graduate studies at UNLV. And also, my parents Judy and Jay Reppart for their never ending love and support they have given during this time. v Table of Contents Abstract ....................................................................................................................................... iii Acknowledgements ..................................................................................................................... v List of Tables ............................................................................................................................. vii List of Figures ........................................................................................................................... viii Chapter 1- Introduction and Background ................................................................................ 1 Chapter 2- Methodology and Analysis .................................................................................... 15 Chapter 3- Results..................................................................................................................... 37 Chapter 4- Discussion ............................................................................................................... 42 Chapter 5- Conclusion ............................................................................................................. 46 References .................................................................................................................................. 48 Curriculum Vitae ...................................................................................................................... 55 vi List of Tables Table 2.1 Analysis of Pre-Shock Sample ................................................................................ 32 Table 2.2 Time, Distance and Velocity of Dynamic Compression Experiment #1 ............. 33 Table 2.3 Time, Distance and Velocity of Dynamic Compression Experiment #2 ............. 34 Table 2.4 Calculated Pressure of DAC Experiment .............................................................. 35 Table 2.5 Comparison of Anzellini et al. 2014 ........................................................................ 36 vii List of Figures Figure 1.1 Phase Diagram of Silica ......................................................................................... 10 Figure 1.2 Backscatter Image of Maskelynite ........................................................................ 11 Figure 1.3 Diamond Anvil Cell Diagram ................................................................................ 12 Figure 1.4 Shock Experiment Sample Chamber Design ....................................................... 13 Figure 1.5 Diagram of the Reverberative Shock Technique ................................................. 14 Figure 2.1 Zagami Diamond Anvil Cell .................................................................................. 22 Figure 2.2 Experimental Impact Laboratory Dynamic Compression Guns ....................... 23 Figure 2.3 Target Assembly ..................................................................................................... 24 Figure 2.4 Tilt of First Dynamic Compression Experiment ................................................. 25 Figure 2.5 Tilt of Second Dynamic Compression Experiment ............................................. 26 Figure 2.6 Excavated Dynamic Compression Sample ........................................................... 27 Figure 2.7 DAC Image and Pattern Before Masking ............................................................ 28 Figure 2.8 DAC Image and Pattern After Masking............................................................... 29 Figure 2.9 Rietveld Refinement of the Rhenium Pattern .....................................................