Tectonic Lithofacies, Geophysical, and Mineral
Total Page:16
File Type:pdf, Size:1020Kb
U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY TECTONIC LITHOFACIES, GEOPHYSICAL, AND MINERAL-RESOURCE APPRAISAL MAPS OF THE SHERBROOKE-LEWISTON AREA, MAINE, NEW HAMPSHIRE, AND VERMONT, UNITED STATES, AND QUEBEC, CANADA Compiled by Robert H. Moench, Eugene L. Boudette, and Wallace A. Bothner 1999 Prepared in cooperation with the MAINE GEOLOGICAL SURVEY AND THE NEW HAMPSHIRE GEOLOGICAL SURVEY Pamphlet to accompany MISCELLANEOUS INVESTIGATIONS SERIES MAP • 1-1898-E CONTENTS Page Introduction . 1 Tectonic lithofacies (map A), by Robert H. Moench, Eugene L. Boudette, and Wallace A. Bothner ............... 1 Introduction . 1 Summary of plate-tectonic history . 1 Early Paleozoic Penobscottian and Taconian accretions ......................................................... 2 The Laurentian craton (LC) . .. 2 Baie Verte-Brompton line (BBL) and terrane 1 (T1) .................................................... 2 Boil Mountain line (BML) and terrane 2 (T2) . 3 Summary ............................................................................................................. 5 Middle to Late Ordovician magmatism and sedimentation related to the Bronson Hill arc . 5 Late Ordovician and Silurian sedimentation and magmatism related to synconvergent extension . 7 Central Maine and Aroostook-Matapedia troughs (CMT, AMT) ...................................... 7 Connecticut Valley trough (CVT) ............................................................................. 9 Model for Silurian extension . 11 Early Devonian to Pennsylvanian events . ... .......................................................... ............. 12 Mesozoic rift-drift . 13 Complete Bouguer gravity and aeromagnetics (maps B and C), by Wallace A. Bothner, Robert P. Kucks, Christian E. Jahrling II, Michael J. Carnese, and Robert H. Moench ........................................... ........ 13 Introduction . 13 Gravity survey . 13 Aeromagnetic survey . 14 Discussion . 15 Bronson Hill-Boundary Mountains anticlinorium ................................................................. 15 Connecticut Valley trough .............................................................................................. 16 Central Maine trough . 17 Devonian to Pennsylvanian plutons . 17 Jurassic and Cretaceous plutonic and volcanic rocks .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 19 Conclusions ........................................................................................................................... 20 Metallic mineral-resource appraisal (map D), by Robert H. Moench with contributions by Eugene L. Boudette and Richard B. McCammon .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 21 Introduction . 21 Method of metallic mineral-resource assessment . 22 Geologic favorability for individual nonpegmatitic deposit types .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 23 Cambrian to Early Devonian volcanogenic massive-sulfide deposits (VMS) . 23 Area Dv1 (grids 4C to 50) .................................................................................... 24 Area Dv2 (grids 5D to 6E) . 25 Area Dv3 (grid 7F) . 25 Area Dv4 (grids 7G and 8G) .................................................................................. 25 Areas Dv5 (grids 8G to 91, fig. 6) ..................... ...................................................... 25 Area Dv6 (grids 7H and 8H) .................................................................................. 26 Areas DSv 1 (grids 8E to 8G) . 26 Area Sv1 (grids 1A and 2A) ................................................................................... 26 Area Sv2 (grids 4C to 6E) ..................................................................................... 27 Area Sv3 (grid 6E) . 27 Areas Sv4 (grids 7F to 9H, fig. 6) . 28 Areas Sv5 (grids 5E to 6F) . 29 Areas Ouv1 (grids 8G to 91, fig. 6) ......................................................................... 29 Area Olv1 (grids 4D and 4E) .................................................................................. 29 Areas Olv2 (grids 4F to 6F) . 30 Areas Olv3 (grids SF to 8H) . 31 Areas Olv4 (grids 7H to 91, fig. 6) . 31 Areas Olv5 (grids 7G to 8H) ......................... ........ ................. ................................ 31 Areas Olv6 (grids 8H to 91, fig. 6) . 32 Areas Olv7 (grids 8G and 9G, fig. 6) . 33 Areas £ ov 1 (grid 1 C) . 33 Areas £ov2 (grids 2C to 4D) ................................................................................. 33 Possible Cambrian ophiolitic chromium deposits, locally containing platinum ...............·............ 34 Areas £ op 1 (grids 3C to 4D) . 34 Possible polymetallic resources in diapiric serpentinite along Devonian faults . 34 Areas Du1 (grids lC and 3C to 3D) ........................................................................ 34 Possible Jurassic tin-bearing greisen deposits and cassiterite veins related to Conway Granite .... 34 Outline Jtl (grids 7E to 5H through 8H) . 35 Outlines Jt2 (grids 6F to 7F, and 5H to 8H) . 35 Areas Jt3 (grids 5H to 7H) . 36 Ordovician or Silurian copper-molybdenum porphyry deposits . ..