University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Spring 1990 The petrogenesis of the Agamenticus complex and late Paleozoic and Mesozoic tectonics in New England John A. Brooks University of New Hampshire, Durham Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation Brooks, John A., "The petrogenesis of the Agamenticus complex and late Paleozoic and Mesozoic tectonics in New England" (1990). Doctoral Dissertations. 1605. https://scholars.unh.edu/dissertation/1605 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. 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Ann Arbor, MI 48106 THE PETROGENESIS OF THE AGAMENTICUS COMPLEX AND LATE PALEOZOIC AND MESOZOIC TECTONICS IN NEW ENGLAND B/ JOHN A. BROOKS Bachelor of Arts, Boston University, 1974 Master of Science, University of New Hampshire, 1986 DISSERTATION Doctor of Philosophy i n Earth Sciences May, 1990 This dissertation has been examined and approved. Dissertation Co-Director, Dr. Wallace A. Bothner Professor of Geology University of New Hampshire Dissertation Co-Director, Dr. David A. Gust Adjunct Associate Professor of Geology University of New Hampshire Associate Professor and Head Department of Applied Geology Queensland University of Technology Dr. Francis S. Birch Professor of Geophysics University of New Hampshire Dr. Jo Laird Associate Professor of Geology University of New Hampshire Dr. O. Donald Hermes Professor of Geology University of Rhode Island Dedicated to Dr. C. Wroe Wolfe and all geologists like in heart: The Himalayas Rock! Jagged, sculptured rock! Where air is thin, Too thin to breathe. Where mind and blood congeal And sky is just a step away. There you stand, Mighty monuments-ramparts rising- Born from out a Tethys sea You reach for Heaven from Earth. Young you are As mountains go. Only yesterday the waters crossed your face; But deep below the waters your strength was growing. T h en - Quake by quake, fault by fault You rose- To claim the sky. And now 'tis yours. Drink deep of that ethereal blue, For as your winter snows Melt and fade away, So will your form and power decay, And you will sink to p rep are the w ay For a loftier, nobler range of yet another day. From the unpublished collection of C. Wroe Wolfe (Lyons and Brownlow, 1976) ACKNOWLEDGEMENTS Funding for this research is gratefully acknowledged; UNH (CURF and Hubbard Fellowships), GSA (Grants 3728-87 and 3941- 88), AFMS (1988-1990),and Sigma XI, and National Science Foundation ( Dr. D. Gust - Grant EAR-8817184). Geochemical labs at the University of Rhode Island, Boston College, and the USGS (Denver) were instrumental in obtaining geochemical analyses required for this study. Irradiation costs were covered under a US DOE reactor sharing grant (DE-FG02 ER10770) to the MIT reactor. My thanks to Mathew Paige and Nancy Niven for their guidance at the geochemical labs of Boston College and the University of Rhode Island, respectively. The support, encouragement, and education offered by my advisors laid the foundation for the completion of this dissertation. With Linda Hoadley at the helm, the office staff, past and present, helped smooth over many a bump in my progress. But most of all my gratitude is extended to the my wife, Janice, for her years of loving support. TABLE O F CONTENTS DEDICATION.........................................................................................................................iii ACKNOWLEDGMENTS......................................................................................................iv LIST OF FIGURES......................................................................................................... x-xii LIST OF PLATES................................................................................................................xiii LIST OF TABLES................................................................................................................xiv ABSTRACT................................................................................................................... xv-xvii CHAPTER 1 INTRODUCTION............................................................................... 1 CHAPTER 2 GEOLOGY AND GEOPHYSICS OF CENTRAL COASTAL NEW ENGLAND AND WEST-CENTRAL MAINE: IMPLICATIONS FOR MESOZOIC IGNEOUS COMPLEXES...............................................................................7 I. INTRODUCTION...................................................................................................7 II. REGIONAL SETTING....................................................................................... 13 Massabesic-Merrimack-Rye Blocks ...................................................13 Central Maine Terrane ............................................................................. 19 Terranes of southeastern New England ............................................19 Casco Bay Block ........................................................................................20 Gulf of Maine .............................................................................................. 21 III. DATA COMPILATION AND PROCESSING..............................................24 IV. RESULTS..........................................................................................................26 Mesozoic Plutons .......................................................................................32 Massabesic-Merrimack-Rye Block ......................................................36 Casco Bay Block ........................................................................................38 Kearsarge Central Maine Synclinorium .......................................... 39 Zones of the Boston Platform................................................................39 Nashoba Zone ............................................................................... 40 Marlboro-Newbury Zone ............................................................. 40 Esmond-Dedham Zone ............................................................... 41 Offshore Lithotectonic-Geophysical Correlations .................43 V. DISCUSSION.................................................................................................... 45 IMPLICATIONS FOR REGIONAL TECTONICS.................................45 IMPLICATIONS FOR MESOZOIC IGNEOUS ACTIVITY................51 CHAPTER 3 PETROGENESIS OF THE AGAMENT1CUS COMPLEX: SOUTHWESTERN MAINE..............................................................................................54 I. INTRODUCTION................................................................................................ 54 Previous Work ............................................................................................ 55 Geologic Setting ........................................................................................ 58 Models for the petrogenesis of A-type magmas ..................... 60 II. ANALYTICAL TECHNIQUES..........................................................................61 III. RESULTS...........................................................................................................63 Petrography and mineral chemistry ..................................................64 Biotite Granite ............................................................................. 64 Alkalic Granite to Quartz Syenite ....................................... 68 Aegirine Alkalic Granite ............................................................71