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A New Stratigraphic and Structural Interpretation of Granulite-Facies Metamorphic Rocks in the Brimfield-Sturbridge Area, Massachusetts And" (1989)

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A New Stratigraphic and Structural Interpretation of Granulite-Facies Metamorphic Rocks in the Brimfield-Sturbridge Area, Massachusetts And University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations 1896 - February 2014 1-1-1989 A new stratigraphic and structural interpretation of granulite- facies metamorphic rocks in the Brimfield-Sturbridge area, Massachusetts and Henry Newhall Berry University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_1 Recommended Citation Berry, Henry Newhall, "A new stratigraphic and structural interpretation of granulite-facies metamorphic rocks in the Brimfield-Sturbridge area, Massachusetts and" (1989). Doctoral Dissertations 1896 - February 2014. 881. https://scholarworks.umass.edu/dissertations_1/881 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations 1896 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. DATE DUE 4 iqqO 199I —OCT 0 T"1§§2- i UNIVERSITY LIBRARY UNIVERSITY OF MASSACHUSETTS AT AMHERST MORRILL LD 3234 M267 1989 B534 A NEW STRAT IGRAPHI C AND STRUCTURAL INTERPRETATION OF GRANUL I TE -FAC IES METAMORPHIC ROCKS IN THE BRIMFIELD-STDRBRIDGE AREA, MASSACHUSETTS AND CONNECT ICDT A Dissertation Presented by HENRY NEWHALL BERRY IV Submitted to the Graduate School of the University of Massachusetts in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 1989 Department of Geology and Geography Copyright by Henry Newhall Berry IV 1989 All Rights Reserved A NEW STRAT IGRAPH IC AND STRUCTURAL INTERPRETATION OF GRANULITE-FACIES METAMORPHIC ROCKS IN THE BRIMFIELD-STURBRIDGE AREA, MASSACHUSETTS AND CONNECTICUT A Dissertation Presented by HENRY NEWHALL BERRY IV Approved as to style and content by Peter Robinson, Chairman of Committee / cm,(hiJ [L 9} H I Donald 0. Wise, Member Michael L. Williams, Member John Tfl Cheney, Member rf— Judith S. Young, Member (7^ Charles W. Pitrat, Acting Head Department of Geology and Geography To Joan, Angela, and Christopher, with love. iv ACKNOWLEDGMENTS The expertise, enthusiasm, guidance, and commitment to excellence demonstrated by Professor Peter Robinson have strongly influenced my experience at the University of Massachusetts and this project in particular. He has shown me that good ideas need to be pursued by hard work. Professor Leo Hall taught an excellent field geology course. With Professor Hall on an outcrop with a student, it was a three-way conversation. He taught me how to look at rocks. Professor Hall contributed fundamentally to my professional and personal growth. I thank the members of my dissertation committee for being patient with me and for being supportive in the final panic-filled weeks. I also thank faculty members S.A. Morse and Howard Jaffe who were not on my dis- sertation committee. The students and faculty of the Department of Geology and Geography have provided a cooperative, open, and stimulating academic environment. For conversations relevant to this dissertation I thank the following students and former students: Mike Field, Art Goldstein, Peter Thompson, John Schumacher, Kurt Hollocher, Page Fallon, David Elbert, Ginny Peterson, Jenny Thomson, George Springston, Mike Hamilton, and Peter Panish. v Additional comments on field trips and at meetings by Allan Ludman, Philip Osberg, David Roy, Norm Hatch, John Lyons, Arthur Hussey, Bob Tracy, Peter Crowley, Peter Gromet, Bob Wintsch, Wally Bothner, and Dykstra Eusden are appreciated. Unpublished data have been generously provided by Barbara Barreiro, Robert Zartman, and Kurt Hollocher. The electron microprobe analyses were obtained by Dave Elbert to whom I am grateful- Thin sections were made at the University of Massachusetts by Tony Kodriko. Paper copies of topographic maps for Westford, Connecticut were provided by Sid Quarrier of the Connecticut Department of Natural History. Mylar base maps for final production were borrowed from the Connecticut Department of Transportation and from Dennis Swartout at the N.C.I.C. office at the University of Massachusetts. Special thanks are extended to Roy Doyan for working with me in producing the high-quality separate negatives, positives, and final composite negatives used for the maps in Plates 1 and 2. Ron Bucchino, Mike Hamilton, and Professor Robinson also helped in map production. For substantial assistance with manuscript and figure preparation I thank Marie Litterer, Professor Robinson, Ali Lochhead, Jenny Thomson, Ginny Peterson, Karin Olson, and especially Mike Hamilton. vi I was partially supported by "beaching assistant, ships in the Department of Geology and Geography from fall 1982 to spring 1985, and by research assistantships for part of the summer of 1983, the summer of 1984, and from 1985 to 1989 funded by the following National Science Foun- dation research grants (to Peter Robinson): EAH-81-16197, EAR-84-10370, EAR-86-08762, and EAR-88-04852. In addition, financial support has been provided by several members of my family. Without their support, my diploma would have been accompanied by even more for- midable bills. More importantly, continuing moral sup- port from my parents, sisters, grandmother, in-laws, and friends has sustained me through the past stressful, and often discouraging year. Joan, Angela, and Chris have waited patiently and long. They remain the most important part of my life, and I regret the inordinate amount of time that this dissertation has kept us apart. I thank them for their unending love. I hope this is worth it. vii ABSTRACT A NEW STRAT I GRAPH I C AND STRUCTURAL INTERPRETATION OF GRANULITE-FACIES METAMORPHIC ROCKS IN THE BRIMFIELD-STURBRIDGE AREA, MASSACHUSETTS AND CONNECTICUT SEPTEMBER 1989 HENRY NEWHALL BERRY IV, B.A. , WESLEYAN UNIVERSITY M.S., UNIVERSITY OF MAINE Ph.D., UNIVERSITY OF MASSACHUSETTS Directed by: Professor Peter Robinson New detailed mapping in Acadian granulite-facies rocks of the Brimf ield-Sturbridge area has identified pre-Silurian and Silurian strata. The pre-Silurian rocks are assigned to the Leadmine Pond Gneiss, named herein, which is dominated by plagioclase-quartz-biotite gneiss, commonly with interlayered amphibolite or pyroxene gran- ulite . Subordinate schist , quartzite, calc-silicate granulite , and marble are interlayered . The Leadmine Pond Gneiss represents the local sialic basement of the Merrimack belt. Possible correlatives include the Monson Gneiss to the west, or the Nashoba or Cushing Formations to the east. The Silurian rocks are correlated with the Rangeley sequence of New Hampshire and Maine. The lower Rangeley contains thin units of white, sulfidic schist and layered Ylll* » • . calc-silicate granulita similar "to formations higher in the sequence The basement and cover together are repeated in a series of thin slices interpreted to comprise a thrust- duplex stucture . Stratigraphic offset implies east-side- up motion on the faults. The thrusting, which pre-dates peak metamorphism, is assigned to the west-directed nappe-stage of Acadian deformation. After intrusion of tonalite and metamorphism to about 700<>C and 6.5 kbar, the region was overturned to the east in a major back- folding event. Associated features include west-plunging lineation, asymmetric shear fabrics, and mylonite zones, all with a west-side-up shear sense. The last major phase of deformation included asymmetric, upright folds and a shallow-plunging sillimanite lineation. The first occurrence of wollastonite in central Massachusetts is documented, from an anorthite-diopside- quartz-calcite-scapolite rock. Mineral textures and phase relations suggest the following: 1 ) anorthite + calcite reacted to form scapolite in small areas of the rock which contain sodium. 2) Calcite + quartz reacted to form wollastonite, perhaps by a drop in Xco2 . 3) Grossular-rich garnet formed simultaneously from wol- lastonite + anorthite, and from anorthite + quartz + calcite- With increasing pressure and temperature, the fluid composition was buffered and the garnet composition ix became more calcic by continuous reaction. The resulting P-T path is counterclockwise, consistent with previous results from politic schists. x TABLE OF CONTENTS Page ACKNOWLEDGMENTS v ABSTRACT viii LIST OF TABLES xvi LIST OF FIGURES xvii LIST OF PLATES xxi Chapter 1. INTRODUCTION 1 Purpose 1 Location and Physiography 2 Methods 7 Field Methods 7 Comment on Maps 9 The Pipeline 11 Laboratory Methods 13 Previous Work 13 Regional Geologic Setting 16 2 . STRATIGRAPHY 27 The Critical Role of Stratigraphy 27 Division of the Map into Belts 28 Overview of the Stratigraphic Units 31 Leadmine Pond Gneiss 35 Name 35 Distribut i on 36 Lower Contact 37 General Description 37 Little Alum Pond Belt 40 East Brimf ield Belt 47 Janes Hill Belt 50 May Brook Belt 57 Bald Hill Belt 59 Leadmine Belt 59 Genera 1 Statement 59 OZlf 61 Western OZls 65 Western 0Z11 66 OZlq 69 xi TABLE OF CONTENTS Page OZlm 71 OZlr 72 Eastern OZ11 73 Eastern OZls 78 Hamant Brook Belt 81 Relationships among Belts 82 Protolith and Depositional Environment. 83 Brimfield Member of the Rangeley Formation. 86 Name 86 Distribution 88 Lower Contact 88 General Description 92 Rattlesnake Mtn. Belt 99 Western units 100 White schist 104 Pipeline trench exposure 106 Burley Hill area 109 Amphibol ite 114 Little Alum Pond Belt 117 The unconformity 117 Undif f erent iated schist and granul ite 119 Feldspathic gneiss lens 121 Srcs 122 Srg 122 Srt 123 Sulfidic schist and sulfidic granulite units
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