'Tillite', Boston Basin
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A Roxbury Review: Conglomerates of Greater Boston
C2-1 A ROXBURY REVIEW by Margaret D. Thompson, Department of Geosciences, Wellesley College Anne M. Grunow, Byrd Polar Research Center, Ohio State University INTRODUCTION Conglomerate throughout the Boston Basin in eastern Massachusetts (Fig. 1) has long been called after the Roxbury district of Boston (early references in Holmes, 1859 and Shaler, 1869) and subdivided into three members typified by strata in the encircling communities of Brookline, Dorchester and the Squantum section of Quincy, MA (Emerson, 1917). NEIGC field trips, beginning with one led by W.O. Crosby in 1905, and also GSA-related field trips have provided regular opportunities for generations of geologists to debate the depositional settings of all of these rocks, particularly the possible glacial origin of the Squantum "Tillite". It appears, however, that none of these outings has ever included a stop in Roxbury itself (Table I and lettered localities in Fig. 1). A main purpose of this trip will be to visit the nominal Roxbury type locality in a section of the historic quarries where recent re-development includes the newly opened Puddingstone Park. Other stops will permit comparison of type Roxbury Conglomerate with other rocks traditionally assigned to this formation and highlight geochronological and paleomagnetic data bearing on the ages of these units. Table I. Forty Years of Field Trips in the Roxbury Conglomerate Stop locations Trip leader(s)/year Title (listed alphabetically; (abbreviations below) Caldwell (1964) The Squantum Formation: Paleozoic Tillite or -
During Neoproterozoic Glaciations with Evolutionary Implications
Geosciences 2012, 2, 90-108; doi:10.3390/geosciences2020090 OPEN ACCESS geosciences ISSN 2076-3263 www.mdpi.com/journal/geosciences Review The Location and Styles of Ice-Free “Oases” during Neoproterozoic Glaciations with Evolutionary Implications Daniel Paul Le Heron Department of Earth Sciences, Royal Holloway University of London, Queen’s Building, Egham TW200EX, UK; E-Mail: [email protected]; Tel.: +0044-1784-443615; Fax: +0044-1784-471780 Received: 13 March 2012; in revised form: 10 April 2012 / Accepted: 17 May 2012 / Published: 29 May 2012 Abstract: Evidence based on molecular clocks, together with molecular evidence/biomarkers and putative body fossils, points to major evolutionary events prior to and during the intense Cryogenian and Ediacaran glaciations. The glaciations themselves were of global extent. Sedimentological evidence, including hummocky cross-stratification (representing ice-free seas affected by intra-glacial storms), dropstone textures, microbial mat-bearing ironstones, ladderback ripples, and wave ripples, militates against a “hard” Snowball Earth event. Each piece of sedimentological evidence potentially allows insight into the shape and location, with respect to the shoreline, of ice-free areas (“oases”) that may be viewed as potential refugia. The location of such oases must be seen in the context of global paleogeography, and it is emphasized that continental reconstructions at 600 Ma (about 35 millions years after the “Marinoan” ice age) are non-unique solutions. Specifically, whether continents such as greater India, Australia/East Antarctica, Kalahari, South and North China, and Siberia, were welded to a southern supercontinent or not, has implications for island speciation, faunal exchange, and the development of endemism. -
Neoproterozoic Glaciations in a Revised Global Palaeogeography from the Breakup of Rodinia to the Assembly of Gondwanaland
Sedimentary Geology 294 (2013) 219–232 Contents lists available at SciVerse ScienceDirect Sedimentary Geology journal homepage: www.elsevier.com/locate/sedgeo Invited review Neoproterozoic glaciations in a revised global palaeogeography from the breakup of Rodinia to the assembly of Gondwanaland Zheng-Xiang Li a,b,⁎, David A.D. Evans b, Galen P. Halverson c,d a ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia b Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA c Earth & Planetary Sciences/GEOTOP, McGill University, 3450 University St., Montreal, Quebec H3A0E8, Canada d Tectonics, Resources and Exploration (TRaX), School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia article info abstract Article history: This review paper presents a set of revised global palaeogeographic maps for the 825–540 Ma interval using Received 6 January 2013 the latest palaeomagnetic data, along with lithological information for Neoproterozoic sedimentary basins. Received in revised form 24 May 2013 These maps form the basis for an examination of the relationships between known glacial deposits, Accepted 28 May 2013 palaeolatitude, positions of continental rifting, relative sea-level changes, and major global tectonic events Available online 5 June 2013 such as supercontinent assembly, breakup and superplume events. This analysis reveals several fundamental ’ Editor: J. Knight palaeogeographic features that will help inform and constrain models for Earth s climatic and geodynamic evolution during the Neoproterozoic. First, glacial deposits at or near sea level appear to extend from high Keywords: latitudes into the deep tropics for all three Neoproterozoic ice ages (Sturtian, Marinoan and Gaskiers), al- Neoproterozoic though the Gaskiers interval remains very poorly constrained in both palaeomagnetic data and global Rodinia lithostratigraphic correlations. -
Quincy Report
2019 GREATEST FLOOD RISK: HISTORICAL FLOOD EVENTS SEVERE WINTER • 9/1938 “The Great New England Hurricane” 10-17 inches of rain and 20-foot storm surge WEATHER COASTAL EROSION • 2/1978 “Blizzard of ’78” 30 inch snowfall, 30-foot waves off shore 24 RL claims COASTAL AND INLAND FLOODING • 10/1991 “Perfect Storm” 25 foot waves coincided with high tide 69 RL claims NOR’ EASTERS • 4/2010 “Nor’easter” 7 inches rain, coastal flooding and high tide. 52 RL claims • 1/2018 Nor’easter “Greyson” Peak winds coinciding with high tide broke Boston Harbor 1978 high tide record. • 3/2018- Nor’easters “Riley & Skylar” Blizzard, high wind and storm surge. FEMA DR-4372/ 4379 2) Identify Risk from “All Hazards” TOP NATURAL HAZARD RISKS FOR QUINCY image sample Coastal Flooding Flood Inland Flooding Storms and Tides Related Culvert Failures Storm Surge Sea Level Rise Climate Severe Snow and Blizzards Change Winter Extreme Precipitation Ice Storms Hurricanes Coastal Climatic Nor’easters Related Erosion & Shoreline Change Tropical Storm Tsunami Urban Fire Fire Earthquake Geologic Wildfire Landslides High Wind Severe Extreme Temperature (Heat and Cold Tornado Weather Drought Thunderstorm AREAS OF FLOODING CONCERNS FEMA REPETITIVE LOSS CLAIMS RL HOUGHS NECK GERMANTOWN RL FURNACE BROOK Identify extent & magnitude of flooding from tides, storm surge, and sea level rise… CLIMATE CHANGE FLOODING IMPACTS • Recommended approach for sea level rise estimates for projecting future coastal flooding risk in Quincy MA Sea Level Rise Time Period Projection² Likely Range³ (Feet) -
E:\Published Issues\Episodes\20
540 by Shuhai Xiao1, Guy M. Narbonne2, Chuanming Zhou3, Marc Laflamme4, Dmitriy V. Grazhdankin5, Malgorzata Moczydlowska-Vidal6, Huan Cui7 Towards an Ediacaran Time Scale: Problems, Protocols, and Prospects 1 Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA. E-mail: [email protected] 2 Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada 3 Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China 4 University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario L5L 1C6, Canada 5 Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, prospekt Akademika Koptyuga 3, Novosibirsk 630090, Russia 6 Department of Earth Sciences, Uppsala University, Villavägen 16, SE 752 36 Uppsala, Sweden 7 Department of Geoscience and NASA Astrobiology Institute, University of Wisconsin, Madison, Wisconsin 53706, USA (Received: 23/12/2015; Accepted: 4/9/2016) DOI:10.18814/epiiugs/2016/v39i4/103886 The Ediacaran Period follows the Cryogenian data to constrain the age, duration, and global extent of Period in the wake of a snowball Earth glaciation and the Shuram negative δ13C excursion, to calibrate and precedes the Cambrian Period with its rising tide of correlate Ediacaran acanthomorph biozones, and to animal radiation. It is also the longest among all determine the temporal relationship among the Shuram stratigraphically -
Quincy, MASSACHUSETTS – January 23, 2013
Quincy, MASSACHUSETTS – January 23, 2013 - - - Regular Meeting of the Quincy School Committee A regular meeting of the Quincy School Committee was held on Wednesday, Regular January 23, 2013 in the City Council Chambers at City Hall. Present were Meeting Mr. Paul Bregoli, Mrs. Kathryn Hubley, Mayor Thomas Koch, Mrs. Emily Lebo, Mrs. Anne Mahoney, Mr. David McCarthy, and Ms. Barbara Isola, Vice Chair. Vice-Chair Presiding - - - There was a moment of silence for Lee Gould, who served as principal of the Montclair, Gridley Bryant, and Beechwood Knoll Elementary Schools. - - - The Superintendent called the roll and all members were present. Also present were: Dr. Richard DeCristofaro, Secretary; Ms. Laura Owens, Clerk; Mr. Michael Draicchio, Ms. Kerry Ginty, Councillor Gutro, Mr. James Hennessy, Ms. Maureen MacNeil, Mr. James McGuire, Mrs. Meg McMillen, Mrs. Robin Moreira, Mr. James Mullaney, Mr. Kevin Mulvey, Mrs. Ellen Murray, Mrs. Maura Papile, Assistant Superintendent Colleen Roberts, Mr. Frank Santoro, Mr. Keith Segalla, Mr. Kevin Segalla, Mr. Robert Shaw, Ms. Judy Todd, Mrs. Ruth Witmer; Quincy High School Student Representative to the School Committee Ms. Lindsay Schrier; and Ms. Allison Cox, President, Quincy Education Association. - - - Mr. McCarthy made a motion, seconded by Mrs. Hubley, to approve the Regular Regular Meeting Meeting minutes for January 9, 2013. On a voice vote, the ayes have it. Minutes Approved 1/9/2013 Mr. McCarthy made a motion, seconded by Mrs. Lebo, to approve the Executive Executive Session Session minutes for January 9, 2013. On a voice vote, the ayes have it. Minutes Approved 1/9/2013 - - - On behalf of a group parents from across the city present at the meeting, Mrs. -
New Geochronological Constraints on the Timing of Magmatism for the Bull Arm Formation, Musgravetown Group, Avalon Terrane, Northeastern Newfoundland
Current Research (2017) Newfoundland and Labrador Department of Natural Resources Geological Survey, Report 17-1, pages 1-17 NEW GEOCHRONOLOGICAL CONSTRAINTS ON THE TIMING OF MAGMATISM FOR THE BULL ARM FORMATION, MUSGRAVETOWN GROUP, AVALON TERRANE, NORTHEASTERN NEWFOUNDLAND A.J. Mills, G.R. Dunning1, M. Murphy1 and A. Langille1 Regional Geology Section 1Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, NL, A1B 3X5 ABSTRACT The Bull Arm Formation is one of the most areally extensive volcanic units in the Avalon Terrane of Newfoundland. His- torically, the age has been interpreted from the single previous U–Pb zircon age (570 +5/-3 Ma) obtained from a rhyolite flow on Wolf Island, where no contact relations are exposed. This rhyolite was later re-interpreted as the lower part of the overly- ing Rocky Harbour Formation but the initial interpretation as Bull Arm Formation had by then become entrenched in the lit- erature. New U–Pb zircon (CA-TIMS) geochronology results have been obtained for two rock samples from the volcanic-dom- inated Bull Arm Formation, Musgravetown Group, on the Bonavista Peninsula (Plate Cove volcanic belt) of northeastern Newfoundland, and one sample from the Isthmus that connects the Avalon Peninsula to the rest of the Island. A 40-cm-thick crystal-ash tuff near the base of the Plate Cove volcanic belt, at the roadcut east of Summerville, yielded an age of 592 ± 2.2 Ma. A lapilli tuff, located approximately 1800 m to the east, at the eastern margin of the volcanic belt, yielded an age of 591.3 ± 1.6 Ma. -
Retallack 2014 Newfoundland Ediacaran
Downloaded from gsabulletin.gsapubs.org on May 2, 2014 Geological Society of America Bulletin Volcanosedimentary paleoenvironments of Ediacaran fossils in Newfoundland Gregory J. Retallack Geological Society of America Bulletin 2014;126, no. 5-6;619-638 doi: 10.1130/B30892.1 Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geological Society of America Bulletin Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Notes © 2014 Geological Society of America Downloaded from gsabulletin.gsapubs.org on May 2, 2014 Volcanosedimentary paleoenvironments of Ediacaran fossils in Newfoundland Gregory J. -
The Stratigraphic Relationship Between the Shuram Carbon Isotope
Chemical Geology 362 (2013) 250–272 Contents lists available at ScienceDirect Chemical Geology journal homepage: www.elsevier.com/locate/chemgeo The stratigraphic relationship between the Shuram carbon isotope excursion, the oxygenation of Neoproterozoic oceans, and the first appearance of the Ediacara biota and bilaterian trace fossils in northwestern Canada Francis A. Macdonald a,⁎, Justin V. Strauss a, Erik A. Sperling a, Galen P. Halverson b, Guy M. Narbonne c, David T. Johnston a, Marcus Kunzmann b, Daniel P. Schrag a, John A. Higgins d a Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St., Cambridge, MA 02138, United States b Department of Earth and Planetary Sciences/GEOTOP, McGill University, Montreal, QC H3A 2T5, Canada c Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada d Princeton University, Guyot Hall, Princeton, NJ 08544, United States article info abstract Article history: A mechanistic understanding of relationships between global glaciation, a putative second rise in atmospher- Accepted 27 May 2013 ic oxygen, the Shuram carbon isotope excursion, and the appearance of Ediacaran-type fossil impressions and Available online 7 June 2013 bioturbation is dependent on the construction of accurate geological records through regional stratigraphic correlations. Here we integrate chemo-, litho-, and sequence-stratigraphy of fossiliferous Ediacaran strata Keywords: in northwestern Canada. These data demonstrate that the FAD of Ediacara-type fossil impressions in north- Ediacaran western Canada occur within a lowstand systems tract and above a major sequence boundary in the infor- Shuram Windermere mally named June beds, not in the early Ediacaran Sheepbed Formation from which they were previously δ13 Carbon-isotope reported. -
Insights Into Chemical Weathering of the Upper Continental Crust from the Geochemistry of Ancient Glacial Diamictites
Available online at www.sciencedirect.com ScienceDirect Geochimica et Cosmochimica Acta 176 (2016) 96–117 www.elsevier.com/locate/gca Insights into chemical weathering of the upper continental crust from the geochemistry of ancient glacial diamictites Su Li a,b,⇑, Richard M. Gaschnig b,2, Roberta L. Rudnick b,1 a School of Geosciences, China University of Petroleum (East China), Qingdao 266555, China b Geology Department, University of Maryland, College Park, MD 20742-421, USA Received 12 June 2015; accepted in revised form 12 December 2015; Available online 21 December 2015 Abstract Glacial diamictites, with ages ranging from 2900 to 0.01 Ma, record the changing composition of the upper continental crust through time (Gaschnig et al., 2014). Li concentrations and isotopic compositions, combined with Pb isotopic compo- sitions, chemical index of alteration (CIA) values and relative Sr concentrations are used here to assess the degree of chemical weathering recorded in these deposits and the origin of this signature. The d7Li values of most of the diamictites (ranging from À3.9 to +3.5) are lower than those of mantle-derived basalts (+3.7 ± 2, 2r), and the low d7Li values are generally accompa- nied by high CIA and low Sr/Sr* values (or Sr depletion factor, Sr/Sr* = Sr/(Ce*Nd)0.5), reflecting a weathering signature that may have derived from pre-depositional, syn-depositional, and/or post-depositional weathering processes. Profiles through three glacial diamictites with relatively high CIA (a fresh road cut of the Neoproterozoic Nantuo Formation (CIA = 62– 69), and drill cores through the Paleoproterozoic Timeball Hill (CIA = 66–75) and Duitschland Formations (CIA = 84– 91)) do not show evidence of significant post-depositional weathering. -
UC Berkeley UC Berkeley Previously Published Works
UC Berkeley UC Berkeley Previously Published Works Title Neoproterozoic glacial origin of the Great Unconformity. Permalink https://escholarship.org/uc/item/5nn1z7m4 Journal Proceedings of the National Academy of Sciences of the United States of America, 116(4) ISSN 0027-8424 Authors Keller, C Brenhin Husson, Jon M Mitchell, Ross N et al. Publication Date 2019 DOI 10.1073/pnas.1804350116 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Neoproterozoic glacial origin of the Great Unconformity Preprint ∗ C. Brenhin Keller1,2, Jon M. Husson3, Ross N. Mitchell4, William F. Bottke5, Thomas M. Gernon6, Patrick Boehnke7, Elizabeth A. Bell8, Nicholas L. Swanson-Hysell2, and Shanan E. Peters9 1Berkeley Geochronology Center 2Department of Earth and Planetary Science, University of California, Berkeley 3School of Earth and Ocean Sciences, University of Victoria 4Department of Applied Geology, Curtin University 5Southwest Research Institute, Boulder 6Ocean and Earth Science, University of Southampton 7Department of the Geophysical Sciences, The University of Chicago 8Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles 9Department of Geoscience, University of Wisconsin, Madison Abstract The Great Unconformity, a profound gap in Earth’s stratigraphic record often evident below the base of the Cambrian system, has remained among the most enigmatic field observations in Earth science for over a cen- tury. While long associated directly or indirectly with the occurrence of the earliest complex animal fossils, a conclusive explanation for the formation and global extent of the Great Unconformity has remained elusive. Here we show that the Great Unconformity is associated with a set of large global oxygen and hafnium isotope excursions in magmatic zircon that suggest a late Neoproterozoic crustal erosion and sediment subduction event of unprecedented scale. -
Toward a Neoproterozoic Composite Carbon-Isotope Record
Toward a Neoproterozoic composite carbon-isotope record Galen P. Halverson† Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA, and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Building 54-1126, Cam- bridge, Massachusetts 02139, USA Paul F. Hoffman Daniel P. Schrag Adam C. Maloof‡ Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA A. Hugh N. Rice Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria ABSTRACT framework for a new, high-resolution model Various workers have compiled composite carbon-isotope record for the Neoproterozoic !13C records for the Neoproterozoic (e.g., Hayes Glacial deposits of Sturtian and Marinoan comprising new !13C (carbonate) data from et al., 1999; Jacobsen and Kaufman, 1999; Wal- age occur in the well-studied Neoproterozoic Svalbard (Akademikerbreen Group) and ter et al., 2000), but like attempts to construct successions of northern Namibia, South Aus- Namibia (Otavi Group) and data in the lit- 87Sr/86Sr records for this time period (Melezhik tralia, and northwestern Canada. In all three erature from Svalbard, Namibia, and Oman. et al., 2001), these compilations have suffered regions, the Marinoan glaciation is presaged A new U-Pb zircon age of 760 ± 1 Ma from from low sample density, limited availability by a large negative !13C anomaly, and the cap an ash bed in the Ombombo Subgroup in of chronostratigraphically well-constrained carbonates to both glacial units share a suite Namibia provides the oldest direct time-cali- data, and the consequent dependence on many of unique sedimentological, stratigraphic, bration point in the compilation, but the time tenuous correlations.