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Geochronological and Geochemical Constraints on The University of Kentucky UKnowledge Theses and Dissertations--Earth and Environmental Sciences Earth and Environmental Sciences 2018 GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF THE CARTOOGECHAYE TERRANE, WESTERN NORTH CAROLINA: IMPLICATIONS FOR THE LATE PRECAMBRIAN TO EARLY PALEOZOIC EVOLUTION OF THE EASTERN LAURENTIAN MARGIN Kevin B. Walsh Jr. University of Kentucky, [email protected] Digital Object Identifier: https://doi.org/10.13023/etd.2018.231 Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Walsh, Kevin B. Jr., "GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF THE CARTOOGECHAYE TERRANE, WESTERN NORTH CAROLINA: IMPLICATIONS FOR THE LATE PRECAMBRIAN TO EARLY PALEOZOIC EVOLUTION OF THE EASTERN LAURENTIAN MARGIN" (2018). Theses and Dissertations--Earth and Environmental Sciences. 57. https://uknowledge.uky.edu/ees_etds/57 This Master's Thesis is brought to you for free and open access by the Earth and Environmental Sciences at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Earth and Environmental Sciences by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless an embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Kevin B. Walsh Jr., Student Dr. David P. Moecher, Major Professor Dr. Edward W. Woolery, Director of Graduate Studies GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF THE CARTOOGECHAYE TERRANE, WESTERN NORTH CAROLINA: IMPLICATIONS FOR THE LATE PRECAMBRIAN TO EARLY PALEOZOIC EVOLUTION OF THE EASTERN LAURENTIAN MARGIN THESIS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the College of Arts and Sciences at the University of Kentucky By Kevin Barry Walsh Jr. Lexington, Kentucky Director: Dr. David P. Moecher, Professor of Earth and Environmental Sciences Lexington, Kentucky 2018 Copyright© Kevin Barry Walsh Jr. 2018 ABSTRACT OF THESIS GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF THE CARTOOGECHAYE TERRANE, WESTERN NORTH CAROLINA: IMPLICATIONS FOR THE LATE PRECAMBRIAN TO EARLY PALEOZOIC EVOLUTION OF THE EASTERN LAURENTIAN MARGIN The Cartoogechaye terrane (CT) is an enigmatic migmatite terrane within the Central Blue Ridge province of the southern Appalachians. Previous work identified exotic Pb isotope compositions within the CT (Quinn, 2012). More recent studies that mapped the extent of potentially exotic metaigneous lithologies yield U-Pb zircon ages consistent with a native Laurentian margin metasedimentary origin (Larkin, 2016). This study focused on the possible extent of similar lithologies in the Clyde quadrangle and provides further constraints on the crustal affinity of the CT. The Clyde quadrangle consists of four distinct lithologic packages: the CT, Ashe metamorphic suite, Great Smoky Group, and Grenville basement. Five samples within the Clyde quadrangle and one sample from Wayah Bald quadrangle were collected for detrital zircon (DZ) U-Pb geochronology and whole rock geochemistry for comparison similar anlayses from other bedrock units in the region. Dominant DZ age modes consist of the Grenville doublet (1050 Ma and 1150 Ma) or a modified version of it. Minor age modes exist at ~450 Ma, 600-750 Ma, and 1300-1550 Ma. Zircons for all but one sample display heterogeneous external and internal cathodoluminescence morphologies, consistent with a sedimentary protolith for the paragneisses. Whole rock compositions are consistent with weathering of and derivation from a local basement source. U-Pb age data are most consistent with an eastern Laurentian sedimentary provenance for five samples. The presence of 450-460 Ma grains is most consistent with high-grade Taconian regional metamorphism. The lack of a major Shawinigan age mode and zircon morphology for ca. 980-1050 Ma metamorphic zircons indicate that sample CLY16-1 is a syn-orogenic metasediment within the Grenville basement underlying the CT. KEYWORDS: Blue Ridge Province, Grenville Basement, Clyde Quadrangle, Cartoogechaye Terrane, Detrital Zircon Geochronolgy Kevin B. Walsh May 29, 2018 GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF THE CARTOOGECHAYE TERRANE, WESTERN NORTH CAROLINA: IMPLICATIONS FOR THE LATE PRECAMBRIAN TO EARLY PALEOZOIC EVOLUTION OF THE EASTERN LAURENTIAN MARGIN By Kevin Barry Walsh David P. Moecher Director of Thesis Edward W. Woolery Directory of Graduate Studies May, 29th 2018 ACKNOWLEDGMENTS Foremost, I would like to express my gratitude to my advisor, Dr. David Moecher, for his continued support throughout my education and early career guidance. Completing this thesis while working full time would not be possible without Dr. Moecher’s willingness to work remotely with me. I would also like to thank my committee members Dr. Ryan Thigpen and Dr. Kent Ratajeski for their input and edits. I have greatly benefited from having them on my committee, working as a teaching assistant for them, and being a student under them. Funding from the Geological Society of America Student Research Grant program; the Department of Earth and Environmental Sciences FERM fund; and NSF grants EAR 1447605 and 1551341, supported the costs of this research. I appreciate Jason Backus at the Kentucky Geologic Survey for assistance with XRF analysis. Also, I would like to thank my officemates at the University of Kentucky for advice and inspiration. Finally, I would like to thank my parents for their unwavering support through all of my educational and professional ventures. iii TABLE OF CONTENTS Acknowledgments ......................................................................................................... iii List of Figures ................................................................................................................. v Chapter I: Introduction .................................................................................................... 1 Purpose ................................................................................................................3 Geologic setting and Previous Work ....................................................................7 Chapter II. Methods ....................................................................................................... 13 Sample Preparation ............................................................................................ 13 Zircon Imaging .................................................................................................. 14 LA-ICP-MS Analysis ......................................................................................... 15 XRF Whole Rock Geochemical Analysis ........................................................... 18 Chapter III. Sample Description and Petrology .............................................................. 20 CLY15-1 ................................................................................................ 20 CLY15-2 ................................................................................................ 21 CLY15-3 ................................................................................................ 21 CLY15-4 ................................................................................................ 21 CLY16-1 ................................................................................................ 22 WB15-1 .................................................................................................. 22 Chapter IV. Results ....................................................................................................... 28 Geochemistry ..................................................................................................... 28 Geochronology .................................................................................................. 32 CLY15-1 ................................................................................................ 33 CLY15-2 ...............................................................................................
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