DOCSLIB.ORG

Lucas, B., Hollocher, K., Robinson, P., and Mabee, S.B

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lucas, B., Hollocher, K., Robinson, P., and Mabee, S.B 1Geology Department, Union College, Schenectady, NY 12308, [email protected], [email protected] Prescott Intrusive Complex, central Massachusetts, geochemistry and structural reinterpretation 2Geological Survey of Norway, Trondheim, NO-7491, Norway, [email protected] 1 1 2 3 3Massachusetts Geological Survey, U. Mass., Amherst, MA 01003, Benjamin Lucas , Kurt Hollocher , Peter Robinson , Stephen B. Mabee [email protected] Rb Rb Abstract These diagrams help Rb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Rb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb compare Prescott rocks (red Cooleyville Gneiss Cooleyville Gneiss Prescott Gabbro Prescott Gabbro The Prescott Complex of metamorphosed igneous intrusions in the central Bronson Hill Anticlinorium, is predominated by Cooleyville Gneiss (32 samples; A 6D6 B A B squares) with other southern 100 La <163 ppm La >163 ppm 100 Lan/Smn <1.395 Lan/Smn >1.395 449 Ma, Tucker and Robinson, 1990), with lesser Prescott Gabbro, in one large mass and smaller bodies enclosed in the Gneiss (29 samples, 407 Ma). The New England igneous suites, 64 Gneiss is weakly to strongly foliated and lineated, with ~1 to 4 mm grain size and 62-75% SiO . The Gabbro is massive to weakly foliated, fine-grained (<0.5 2 shown in the key. Both mm) to very coarse (~15 mm) with 47-53% SiO2. The wide composition gap implies no genetic relationship, consistent with the ~42 Ma age difference. The Cooleyville Gneiss and 10 10 rocks are calc-alkaline and metaluminous to weakly peraluminous, and all are LREE-enriched with Lan/Yb ratios of 2.3-17 for gneisses, 1.5-4.6 for gabbros. n Prescott Gabbro are M82 OI6 Multi-element diagrams show strong positive anomalies for Pb, Li, and other LILEs, and negative anomalies for Nb, Ta, and, to a lesser extent, Zr and Hf, consistently more similar to 5D2 consistent with arc-related sources. Compositions are like those of the nearby Late Ordovician Monson and Fourmile Gneisses, plutonic roots to the Bronson 1 1 Taconian (Ordovician) rocks 69 Hill Arc, but differ from other local igneous rocks: Early Devonian Erving Formation amphibolite (REE like N-MORB), Middle Devonian Belchertown Intrusion B57, age-dated sample, 159A 6A Concentration/MORB in the Bronson Hill Concentration/MORB 449 Ma (dashed line, Age-dated coarse Garnet-bearing gabbros (380 Ma, strange chemistry), Late Devonian Hardwick Tonalite (360 Ma, mildly alkaline). The complex is exposed within the Late Devonian Prescott Syncline, anticlinorium than to the other hidden by other samples) 6B gabbro, 407 Ma on the east limb apparently intruding the Late Ordovician Partridge Formation, based on near-contact rock types contaminated with schist (including gabbro 0.1 0.1 suites. Monson and Fourmile Gneisses, Taconian Monson with 5 cm garnets), and inclusions of Partridge in Gneiss and Gabbro. On the west limb it is in apparent intrusive contact with Partridge and the Ammonoosuc 6D6 Unusual Cooleyville Gneiss, not Prescott Gabbro C D C Taconian plutonic rocks D and Fourmile gneisses 100 including in the gray average band 100 Prescott gabbro average, +_1 , Volcanics, and fault contact with Fourmile Gneiss of the Kempfield anticline. The north end was originally interpreted as intruding Silurian Clough Quartzite excluding these 5 samples and Devonian Littleton Formation, but the 449 Ma radiometric age contradicts this. The north contact is now interpreted as a southeast-dipping Mesozoic M82 Rare Nb-rich amphibolites normal fault, connecting the previously mapped Ludlow-Lighthouse Hill fault on the west with the New Salem faults to the northeast. We correlate the Typical gneisses 64 Cooleyville geochemically with the plutonic Monson Gneiss, but likely a hypabyssal intrusion into Partridge at a high level in the Taconic arc. The much Cooleyville Gneiss, dated at 449 Ma (Tucker and 10 10 5D2 Robinson, 1990). This is a biotite-epidote-titanite OI6 granodiorite gneiss, with darker inclusions (top). 6A 1 1 Omos 69 159A 6B Concentration/MORB Preliminary Planimetric Bedrock Geologic Map Concentration/MORB Oaf Oaa Cooleyville Gneiss, excluding Mesozoic rocks, Oaa Omo Adakitic gneisses Most amphibolites CANADA Connecticut Valley basin of the Prescott Intrusive Complex and the 6 samples here, +_ 45°N Undifferentiated Ordovician, Dl Oaa Silurian, Devonian stratified rocks Omog Surroundings, Prescott Peninsula, Quabbin 0.1 0.1 Upper Ordovician to lower Silurian Kempfield m Anticline Reservoir Area, Massachusetts Other nearby units Erving Formation Partridge Formation, u Highlandcroft plutonic series Other Taconian plutonic E F E F ri Late Ordovician intrusives, amphibolites (Devonian) o Bears Omos Geology by Peter Robinson (1959-2016) and Kurt Hollocher (1979, 2016) 100 Taconian volcanics Vermont n southwestern Connecticut Den 100 rocks in the Bronson Hill belt li Wendell with compilations from the M.S. Thesis of Jordan Makower,1964 and c Dome gneisses in Bronson Hill Syncline Fault 202 Dry Hill Gneiss, Pelham n and Shelburne Falls belts results from students in Advanced Mapping Classes 1980-1985. y Dea Sf Oamc dome (Late Proterozoc) s Accretionary wedge and forearc é sediments, volcanics p Omo Northern domes, NH s Taconic sequence slope Main body Dated samples (Tucker and Robinson, 1990) a and rise sediments of 10 10 G Oaf Monson Gneiss - m Parautochthonous carbonate bank Ops Opsm y u e i and continental rise sediments ll r Mesozoic brittle faults New a o Ops Autochthonous shelf sediments Ofm Sc V n i York t l Nashoba block, includes late u c Early Devonian Packard Gabbro of Prescott Complex c Precambrian to Devonian rocks i i 1 1 t t m Massabesic Gneiss complex, c n u includes late Precambrian rocks Dpg: Massive, medium- to e i Southern domes, MA, CT a r coarse-grained, weakly foliated, Partridge Formation n Late Precambrian rocks, Pelham Oaa Concentration/MORB l o 43° Concentration/MORB n l dome and in Connecticut Prescott faintly lineated hornblende Taconian volcanics o n i i N Syncline Dpgb Dpgb gabbro Avalon block, includes late Pre- C l H cambrian to Pennsylvanian rocks Oaf Dpgb: Western border facies, c 0.1 n n very coarse, mottled dark-green 0.1 Mid-Proterozoic (Grenville) rocks Pelham Dome o Dl and white hornblende gabbro. y New Salem New Hampshire Magma Highlandcroft plutons, northern New Hampshire Magma s s Other plutonic units Sc Faults G H G H n New Hampshire (Late e Maine 70°W Series (Devonian) Series (Devonian) New 100 100 o n Dl Ordovician-Early Silurian) r i Opce Lower Devonian Erving Formation (Wendell Syncline) Hampshire Oph B a Rochester pluton, NH, Oa Notice the wide, completely Kinsman type M Ops Dea possibly similar to Hardwick Ops l Oa Prescott Gabbro, dated at 407 Ma (Tucker and empty 54-63% SiO2 Kinsman type a 10 r Robinson, 1990). Originally interpreted as a gabbro 10 Opcg Opsm Omo composition gap between the t Lower Devonian Littleton Formation (Prescott Syncline) 43°N n Opcf pegmatite, its composition suggests it’s a cumulate. Prescott Gabbro and e Dl Ops C Cooleyville Gneiss (red - Atlantic Ocean Ops k 1 Upper Silurian Fitch Formation (Prescott Syncline) 1 c Dpgb Opcg squares). The gap is Opcw Hardwick pluton (latest Devonian) a Dpg Packard Sf Concentration/MORB Spaulding type Ops consistent with the 449 Ma Concentration/MORB m Gabbro i Massachusetts Lighthouse S F B r Hill Fault (gneiss) vs. 407 Ma (gabbro) Spaulding type r Ops Highlandcroft plutons, northern NH (Late Ordovician) Lower Silurian Clough Quartzite (Prescott Syncline) Dea 0.1 0.1 e age difference, indicating that Rb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmRb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Rb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Ba Th U Nb' K La Ce Pb Pr Sr Nd Zr'SmEuGd Ti Tb Dy Li Ho Er TmYb Oph M Sc Yb Rb 42°N Ofm Opcg Dpg Element Element Element Element Rhode Opcf the plutons are unrelated. alley Basin Cooleyville Gneiss comparisons Prescott Gabbro comparisons Dpgb Opcw Opce Ops Island Dpgb Omoa Late Ordovician Shallow Intrusive Dl Cooleyville Gneiss of Prescott Complex N Opcw WD Opcg: Well lineated medium-grained gneiss. Opcf Opcf Opce Opce: Coarse-grained, micaceous gneiss. Opcf: Fine-grained gneiss. Connecticut V Ops Opcg Opcw: Coarse-grained micaceous gneiss with Previous interpretation New interpretation Omo Opcw plagioclase megacrysts. Cooleyville Gneiss, having Gabbro Conclusions 0 10 20 30 40 50 km Opce the assemblage quartz- Connecticut 407 Ma 1) Similar geochemistry and age indicate that the Cooleyville Gneiss is a set of Taconian intrusions, Late Ordovician Partridge Formation Ops plagioclase-microcline- Early 73°W 71°W 70°W Oph Wendell Prescott like the Bronson Hill dome gneisses. Cooleyville Intrusion Syncline Syncline Ops: Rusty-weathering garnet-biotite- Devonian muscovite schist. biotite-epidote-titanite, here 72°30’ 72°15’ Opsm: Well-layered, rusty-weathering garnet- 2) Intrusive contacts with the Partridge Formation indicate that the Cooleyville intruded at shallow Opcf Opf Opa biotite-muscovite-sillimanite schist. showing a large allanite Gneiss Ops levels. Oph Opa: Amphibolite. 449 Ma Oph Opsm Opf: Layered gray- to brown-weathering grain (brown) that Omo quartz-feldspar gneiss. Earliest 3) With its Late Ordovician age (449 Ma), the Cooleyville Gneiss can’t have intruded Silurian and Dea Ops Oph: Hornblendite with amphibolite.
Load more

Recommended publications
  • PROVENANCE and TECTONIC HISTORY of METAMORPHIC ROCKS of CENTRAL PARK and NEW YORK CITY Steven J
    PROVENANCE AND TECTONIC HISTORY OF METAMORPHIC ROCKS OF CENTRAL PARK AND NEW YORK CITY Steven J. Jaret1,2, Nicholas D. Tailby1, Keiji Hammond1, E. Troy Rasbury2, Kathleen Wooton2, E. DiPadova1,3, Lisa Smith1,3, Riley Smith1,3, Victoria Yuan1,3, and Noa Jaffe1,3 1Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY. 2Department of Geosciences, Stony Brook University. 3Department of Education, New York City. The rocks underlying much of New York City, frequently referred to as the “Manhattan Prong”, predominately consist of a series of metasedimentary units, which were originally deposited into the Iapetus Ocean and subsequently deformed and metamorphosed during the Taconic, Acadian, and Alleghenian Orogenies (Merguerian and Merguerian , 2014, 2016; van Staal and Barr, 2012). Despite extensive field mapping in parks around Manhattan and subsurface mapping in major infrastructure sites (i.e., building foundations and tunnels), these rocks have not been studied geochemically and isotopically and interpretation within the larger tectonic framework has largely been based on correlation with presumed equivalent units in Connecticut and New England. Here we present new detrital zircon and Nd isotope provenance analyses in the broader geologic context of Northern Appalachia. General Background The Manhattan Schist was originally defined by Hall, 1976 and has been the subject of great debate for nearly 50 years. Merguerian 2004; 2016 has subdivided the original “Manhattan Schist” of Hall into 3 subunits of schistose rocks. He correlated the third unit with the Hartland Schist in Connecticut and thus interpreted these to be fault-bounded schists which were juxtaposed during a middle Ordovician collision between the eastern margin of Laurentia and volcanic arcs (the so-called “Taconic Arc”).
    [Show full text]
  • Preliminary Planimetric Bedrock Geologic Map of the Prescott Peninsula Equivalents
    arc- or back-arc-related tholeiitic basalts and rare andesites and metamorphosed hydrothermally altered Omo Oaf Preliminary Planimetric Bedrock Geologic Map of the Prescott Peninsula equivalents. Locally pillows, graded tuffs, agglomerates and other features are preserved even at Oaa Omos sillimanite grade. They are older than the overlying felsic member dated at 453 ±2 Ma, but the exact age Sf Omo Oaa is presently unknown. Similar rocks in northern New Hampshire (Moench and Aleinikoff, 2002; Rankin and Surroundings, Quabbin Reservoir Area, Massachusetts et al., 2007) are cut by the Joslin Turn pluton with an age of 469 ±2 Ma (late Arenig). More recent U–Pb Kempfield Oaa dating of felsic volcanics in the same area (Aleinikoff et al., 2015) suggests ages in the ranges 480–462 Omog and 458–445 Ma. U–Pb ages from 7 intrusions and 1 volcanic rock in west-central New Hampshire Anticline Geology by Peter Robinson (1959-2016) and his students, (Valley et al., 2015) were the following. The Plainfield and Lebanon tonalites, both cutting 202 Ammonoosuc Volcanics, gave 475 ±5 Ma and 466 ±8 respectively. The Sugar River granodiorite including the M.S. Thesis of Jordan Makower (1964), and intruded the Ammonoosuc at 460 ±3 Ma at the same time as extrusion of a felsic lapilli tuff at 460 ±2 Omos Ma. Wendell Bears results from his Advanced Mapping Classes, 1980-1985. Oaau: Uppermost part of the mafic lower member. Hornblende amphibolite and former coarse Syncline anthophyllite amphibolite extensively retrograded to chlorite. Some of these rocks, especially near the Den top of the unit, contain significant magnetite, and these were followed through a series of folds across Dea Oamc Dated samples (Tucker and Robinson, 1990) the channel west of Little Quabbin Island, based on a ground-magnetic survey on the ice in February Faults 1965.
    [Show full text]
  • Root Zone of the Bernardston Nappe and the Brennan Hill Thrust Involuted by Backfolds and Gneiss Domes in the Mount Grace Area, North-Central Massachusetts
    University of New Hampshire University of New Hampshire Scholars' Repository New England Intercollegiate Geological NEIGC Trips Excursion Collection 1-1-1988 Root Zone of the Bernardston Nappe and the Brennan Hill Thrust Involuted by Backfolds and Gneiss Domes in the Mount Grace Area, North-Central Massachusetts Robinson, Peter Hunt, J. Craigington McEnroe, Suzanne A. Sprinston, George C. Follow this and additional works at: https://scholars.unh.edu/neigc_trips Recommended Citation Robinson, Peter; Hunt, J. Craigington; McEnroe, Suzanne A.; and Sprinston, George C., "Root Zone of the Bernardston Nappe and the Brennan Hill Thrust Involuted by Backfolds and Gneiss Domes in the Mount Grace Area, North-Central Massachusetts" (1988). NEIGC Trips. 447. https://scholars.unh.edu/neigc_trips/447 This Text is brought to you for free and open access by the New England Intercollegiate Geological Excursion Collection at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in NEIGC Trips by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. C-4 ROOT ZONE OF THE BERNARDSTON NAPPE AND THE BRENNAN HILL THRUST INVOLUTED BY BACKFOLDS AND GNEISS DOMES IN THE MOUNT GRACE AREA, NORTH-CENTRAL MASSACHUSETTS by Peter Robinson, J. Craig Huntington, Suzanne A. McEnroe, and George C. Springston Department of Geology and Geography, University of Massachusetts, Amherst, Massachusetts 01003 PURPOSE OF TRIP A new stratigraphic and structural interpretation of the Mount Monadnock area, New Hampshire, (P. J. Thompson, 1985 and this volume) and new work by Elbert (1984,1986,1987, and this volume) in the Bernardston area, Massachusetts and Hinsdale area, New Hampshire, has pointed the way to yet another reinterpretation of the complex geology of the Mount Grace area.
    [Show full text]
  • Tectonic History the Tectonic History of the Presidential Range Begins About 450 Million Years Ago
    Tectonic History The tectonic history of the Presidential Range begins about 450 million years ago. The geologic time scale on pages 2 and 3 show the timing of the main geologic events and the ages of the rocks in the range. To visualize the movement of tectonic plates, land masses, and oceans over time, Chris Scotese of the PALEOMAP project has made a series of global maps. He determined the positions of the plates by measuring the ancient magnetic field locked in magnetic minerals in the rocks. This information yields the paleo-latitude on the globe, but little on the paleo-longitude. For example, from his work we know that much of the plate collisions that formed the Presidential Range occurred south of the equator, but we are not as sure about which lines of longitude the colliding plates were located . On the following paleogeographic illustrations continental plates are shown as olive-green landmasses and include shallow marine platforms. Ocean plates are shown in darker shades of blue in the deep basins of the oceans. Spreading ridges in the oceanic crust are shown with a single line and two arrows pointing in opposite directions. These arrows indicate the direction that newly formed ocean crust moves away from the ridge. Oceanic plates descend beneath continental plates in regions of collision. These trenches or subduction zones are shown with an orange line with teeth. The teeth rest on the plate that does not subduct. These subduction boundaries are analogous to the modern tectonic setting in the Pacific Northwest where the Pacific oceanic plate is subducting beneath the west coast of the North American continental plate producing volcanoes such as Mt.
    [Show full text]
  • Stratigraphy, Geochronology, and Accretionary Terrane Settings of Two Bronson Hill Arc Sequences, Northern New England
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by DigitalCommons@University of Nebraska University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- Published Research US Geological Survey 2003 Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England Robert H. Moench U.S. Geological Survey, [email protected] John N. Aleinikoff U.S. Geological Survey Follow this and additional works at: https://digitalcommons.unl.edu/usgsstaffpub Part of the Earth Sciences Commons Moench, Robert H. and Aleinikoff, John N., "Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England" (2003). USGS Staff -- Published Research. 436. https://digitalcommons.unl.edu/usgsstaffpub/436 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Physics and Chemistry of the Earth 28 (2003) 113–160 www.elsevier.com/locate/pce Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England q,qq Robert H. Moench a,*, John N. Aleinikoff b a US Geological Survey, MS 905, Federal Center, Denver, CO 80225, USA b US Geological Survey, MS 963, Federal Center, Denver, CO 80225, USA Abstract The Ammonoosuc Volcanics, Partridge Formation, and the Oliverian and Highlandcroft Plutonic Suites of the Bronson Hill anticlinorium (BHA) in axial New England are widely accepted as a single Middle to Late Ordovician magmatic arc that was active during closure of Iapetus.
    [Show full text]
  • Geochronology and Tectonic Setting of Ordovician Magmatism and Basin Formation on the Laurentian Margin of New England and Newfoundland Francis A
    Boise State University ScholarWorks Geosciences Faculty Publications and Presentations Department of Geosciences 5-1-2017 Bridging the Gap Between the Foreland and Hinterland II: Geochronology and Tectonic Setting of Ordovician Magmatism and Basin Formation on the Laurentian Margin of New England and Newfoundland Francis A. Macdonald Harvard University Paul M. Karabinos Williams College James L. Crowley Boise State University Eben B. Hodgin Harvard University Peter W. Crockford McGill University This document was originally published in the American Journal of Science by HighWire Press. Copyright restrictions may apply. doi: 10.2475/ 05.2017.02 See next page for additional authors Authors Francis A. Macdonald, Paul M. Karabinos, James L. Crowley, Eben B. Hodgin, Peter W. Crockford, and John W. Delano This article is available at ScholarWorks: https://scholarworks.boisestate.edu/geo_facpubs/358 [American Journal of Science, Vol. 317, May, 2017,P.555–596, DOI 10.2475/05.2017.02] BRIDGING THE GAP BETWEEN THE FORELAND AND HINTERLAND II: GEOCHRONOLOGY AND TECTONIC SETTING OF ORDOVICIAN MAGMATISM AND BASIN FORMATION ON THE LAURENTIAN MARGIN OF NEW ENGLAND AND NEWFOUNDLAND FRANCIS A. MACDONALD*,†, PAUL M. KARABINOS**, JAMES L. CROWLEY***, EBEN B. HODGIN*, PETER W. CROCKFORD§, and JOHN W. DELANO§§ ABSTRACT. Ordovician strata of the Mohawk Valley and Taconic allochthon of New York and the Humber margin of Newfoundland record multiple magmatic and basin-forming episodes associated with the Taconic orogeny. Here we present new U-Pb zircon geochronology and whole rock geochemistry and neodymium isotopes from Early Paleozoic volcanic ashes and siliciclastic units on the northern Appalachian margin of Laurentia. Volcanic ashes in the Table Point Formation of Newfoundland and the Indian River Formation of the Taconic allochthon in New York yield dates between 466.16 ؎ 0.12 and 464.20 ؎ 0.13 Ma.
    [Show full text]
  • Geology of Mascoma Mantled Gneiss Dome Near Hanover, New Hampshire
    University of New Hampshire University of New Hampshire Scholars' Repository New England Intercollegiate Geological NEIGC Trips Excursion Collection 1-1-1971 Geology of Mascoma Mantled Gneiss Dome Near Hanover, New Hampshire Naylor, Richard S. Follow this and additional works at: https://scholars.unh.edu/neigc_trips Recommended Citation Naylor, Richard S., "Geology of Mascoma Mantled Gneiss Dome Near Hanover, New Hampshire" (1971). NEIGC Trips. 148. https://scholars.unh.edu/neigc_trips/148 This Text is brought to you for free and open access by the New England Intercollegiate Geological Excursion Collection at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in NEIGC Trips by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. 28 TRIP A-4 GEOLOGY OF MASCOMA MANTLED GNEISS DOME NEAR HANOVER, NEW HAMPSHIRE Richard S. Naylor Department of Earth and Planetary Sciences Massachusetts Institute of Technology, Cambridge, Mass. Introduction This trip will show the core and mantle rocks of the Mascoma Dome, which is one of the best examples of the Oliverian belt of mantled gneiss domes. The trip will emphasize the geological features which led me to reinterpret the core rocks of the domes as part of an Ordovician Volcanic and intrusive complex--possibly an island arc. The stratigraphy of the area is the classical Littleton (youngest), Fitch, Clough, Ammonoosuc sequence of Billings (1937). My work has added a new stratigraphic unit called "Holts Ledge Gneiss" or "stratified core-rock of the Mascoma Dome" below the Ammonoosuc Volcanics. The area has been mapped at inch to the mile scale by Chapman (1939: Mascoma Quadrangle) and Hadley (1942: Mt.
    [Show full text]
  • Bedrock Geologic Map of the Hanover 7.5' Quadrangle, New Hampshire N
    Bedrock Geologic Map of the Hanover 7.5' Quadrangle, New Hampshire N " 72°22'30"W 72°20'0"W 72°17'30"W 72°15'0"W 0 ' N 5 " 4 0 ° ' 3 5 4 4 ° 3 B' 4 DESCRIPTION OF MAP UNITS EXPLANATION OF INT RU SIVE AND FAU L T ROCKS MAP SYMBOLS Kjd Mafic dikes (Mesozoic) — No Mesozoic diab ase dikes were foun d, Con tac t Beddin g So although L yon s (1958) reported on e on Crafts Hill an d several in trudin g the L eb an on gran ite. (c ertain ) Foliation Sn Con tac t md Metadiabase sills and dikes (unknown age) — A few m etadiab ase dikes of un kn own age (m d) c on sistin g of fin e- to m edium -grain ed horn b len de gn eiss (in ferred) in trude the Partridge Form ation . T heir exten t is lim ited to on e or a few Foliation S1 Con tac t outc rops. (c on c ealed) 35 In tersec tion 35 Amphibolite (unknown age) — Am phib olite, likely m etagab b ro, c rops out Oo9B lin eation 38 as sills within the m etavolc an ic s west of Bald Hill an d in a larger b ody alon g Fault the c rest of Crafts Hill. T he m assive, b loc ky- an d b rown -weatherin g roc k Min eral Min eral lin eation 37 seem s to b e in terc alated with quartz diorite alon g the east side of Crafts Hill.
    [Show full text]
  • Domes, Volcanics, Refolded Folds and Granites: a Transect from the Bronson Hill Arc Into the Central Maine Cover, Northern Presidential Range, New Hampshire J
    Bates College SCARAB All Faculty Scholarship Departments and Programs 2006 Domes, volcanics, refolded folds and granites: A transect from the Bronson Hill arc into the Central Maine cover, Northern Presidential Range, New Hampshire J. Dykstra Eusden Bates College, [email protected] Krista Anderson Bates College Emma Beaudry Bates College Matt Dupee Bates College Rebecca Larkin Bates College See next page for additional authors Follow this and additional works at: http://scarab.bates.edu/faculty_publications Recommended Citation Eusden, J. D., Jr., Anderson, K, Beaudry, E, Dupee, M, Larkin, R , Minor, J. and Welling, D. 2006, Domes, volcanics, refolded folds and granites: A transect from the Bronson Hill arc into the Central Maine cover, Northern Presidential Range, New Hampshire: in Gibson, D., Daly, J and Reusch, D, eds., New England Intercollegiate Geological Conference, 98th Annual Meeting, University of Maine Farmington, ME, p. 167-180. This Conference Proceeding is brought to you for free and open access by the Departments and Programs at SCARAB. It has been accepted for inclusion in All Faculty Scholarship by an authorized administrator of SCARAB. For more information, please contact [email protected]. Authors J. Dykstra Eusden, Krista Anderson, Emma Beaudry, Matt Dupee, Rebecca Larkin, Jesse Minor, and Doug Welling This conference proceeding is available at SCARAB: http://scarab.bates.edu/faculty_publications/11 1 DOMES, VOLCANICS, MIGMATITES, REFOLDED FOLDS AND GRANITES: A TRANSECT FROM THE BRONSON HILL ARC INTO THE CENTRAL MAINE COVER, NORTHERN PRESIDENTIAL RANGE, NEW HAMPSHIRE by Dykstra Eusden, Krista Anderson, Emma Beaudry, Matt Dupee, Rebecca Larkin, Jesse Minor, and Doug Welling, Department of Geology, Bates College, Lewiston, Maine 04240 INTRODUCTION This fieldtrip highlights the recent mapping done by Bates College undergraduate geology majors and Eusden on the north flank of the Presidential Range.
    [Show full text]
  • Tectonic Breccia of Metamorphosed Intrusive Igneous Rocks in an Acadian Shear Zone, Brooks Village, North-Central Massachusetts
    TECTONIC BRECCIA OF METAMORPHOSED INTRUSIVE IGNEOUS ROCKS IN AN ACADIAN SHEAR ZONE, BROOKS VILLAGE, NORTH-CENTRAL MASSACHUSETTS BY PETER S. MORTON CONTRIBUTION NO. 54 DEPARTMENT OF GEOLOGY Si GEOGRAPHY UNIVERSITY OF MASSACHUSETTS AMHERST, MASSACHUSETTS TECTONIC BRECCIA OF METAMORPHOSED INTRUSIVE IGNEOUS ROCKS IN AN ACADIAN SHEAR ZONE, BROOKS VILLAGE, NORTH-CENTRAL MASSACHUSETTS (M.S. Thesis) by Peter s. Morton Contribution No. 54 Department of Geology and Geography University of Massachusetts Amherst, Massachusetts July, 1985 iii TABLE OF CONTENTS Page ABSTRACT ........................................................ 1 INTRODUCTION .................................................... 2 Statement of the Problem 2 Location ................................................... 2 Regional Setting ........................................... 2 Previous Work .............................................. 3 Field Methods .............................................. 6 Acknowledgments ............................................ 6 DESCRIPTION OF ROCK UNITS ....................................... 6 Rangeley Formation ......................................... 7 Paxton Formation .......................................... 11 Coys Hill Granite 12 Hardwick Tonalite ......................................... 12 Brooks Village Tonalite ................................... 13 Breccia Matrix ............................................ 13 Tonalite Clasts in Breccia ................................ 15 Pegmatite ................................................
    [Show full text]
  • Traverse Across the Taconian Orogen
    TRAVERSE ACROSS THE TACONIAN OROGEN KURT HOLLOCHER Geology Department Union College Schenectady, NY 12308 INTRODUCTION In Early Ordovician time the rifted and submerged eastern edge of the North American continent (current coordinates) was located approximately at the present location of the Connecticut River in western New England (Figures lA and 2). To the east, across a narrow ocean basin, lay an island arc. Subduction of oceanic crust beneath the arc allowed the arc to advance toward North America, colliding in Middle to Late Ordovician time (Figures IB to IF). The remnants of the island arc itself are present in western New England as a sequence of Ordovician sediments (e.g., Bradley and Kidd, 1991) and bimodal volcanic and plutonic rocks (e.g., Leo et a\., 1984; Leo, 1985, 1991; Schumacher, 1988; Hollocher, 1993, 1994). The remnants of the island arc are found in four different forms: 1) unmetarnorphosed sediments derived from the arc and forearc regions that were deposited west of the arc on North American crust; 2) variously metamorphosed continental shelf, continental slope, trench, and forearc rocks that became part of the arc's accretionary wedge and were thrust westward onto North America during subduction and collision; 3) interbedded sediments and volcanics associated with arc, and possibly forearc and back arc volcanics; and 4) the plutonic roots to the arc. This trip examines all four of these. THE EARLY PALEOZOIC NORTH AMERICAN CONTINENTAL MARGIN In the Late Precambrian and Early Cambrian much of eastern North America was emergent from the oceans, with Late Precambrian and Early Cambrian sediments accumulating on the continental shelf.
    [Show full text]
  • Bedrock Geology of the Brattleboro Quadrangle, Vermont-New Hampsiiire
    BEDROCK GEOLOGY OF THE BRATTLEBORO QUADRANGLE, VERMONT-NEW HAMPSIIIRE By J. CHRISTOPHER HEPBURN' NEWELL J. TRASK2 JOHN L. ROSENFELD3 JAMES B. THOMPSON, JR.4 VERMONT GEOLOGICAL SURVEY CHARLES A. RATTE, State Geologist AGENCY OF ENVIRONMENTAL CONSERVATION Department of Water Resources and Environmental Engineering MONTPELIER, VERMONT BULLETIN NO. 32 1984 1. Dept. of Geology and Geophysics, Boston College, Chestnut Hill, Mass., 02167 2. U.S. Geological Survey, Reston, Va., 22092 3. Dept. of Earth and Space Sciences, Univ. of California, Los Angeles, Calif., 90024 4. Dept. of Geological Sciences, Harvard Univ., Cambridge, Mass., 02138 TABLE OF CONTENTS Page ABSTRACT 9 CHAPTER 1, INTRODUCTION ............................................. 10 Location................................................................... 10 Previous Geologic Work .............................................. 11 Regional Geologic Setting ............................................ 12 Eastern Sequence-Western Sequence Division ................. 15 Acknowledgements ..................................................... 16 CHAPTER 2, STRATIGRAPHY OF THE WESTERN SEQUENCE ..... 17 General Sequence ....................................................... 17 Precambrian.............................................................. 20 Mt. Holly Complex .................................................. 20 Late Precambrian (?) or Cambrian (?) ............................ 20 Bull Hill Gneiss ....................................................... 20 Hoosac Formation ..................................................
    [Show full text]