Magmatic and Tectonic History of the Leech
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Seismicity in Cascadia
Lithos 332–333 (2019) 55–66 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos Seismicity in Cascadia Michael G. Bostock ⁎, Nikolas I. Christensen, Simon M. Peacock Department of Earth, Ocean and Atmospheric Sciences, The University of British Columbia, Canada article info abstract Article history: We examine spatio-geometric patterns in the density of seismicity within the Cascadia forearc to gain insight into Received 11 July 2018 controls on seismogenesis. Tremor epicenters exhibit the most regular distribution defining a 40–80 km wide 27 December 2018 band extending along almost the entire convergent margin from the southern terminus of Gorda plate subduc- Accepted 23 February 2019 tion in northern California to the central Explorer plate below northern Vancouver Island. Based on prior charac- Available online 26 February 2019 terization of constituent low-frequency earthquakes, the up- and down-dip limits of tremor are assumed to fl Keywords: represent slab isodepth contours at nominal values of 28 and 45 km, between which uids at near-lithostatic Seismicity overpressures are trapped within the subducting slab. Epicenters of earthquakes within the North American Tremor crust are anticorrelated with those of tremor, and concentrated in Washington and northern California where Cascadia they are sandwiched between tremor and the Cascade volcanic arc. Seismicity within the subducting plate Fluids possesses the most limited epicentral distribution. Seismicity is confined to shallow depths off Vancouver Island Subduction and in northern California, and projects to greater depths beneath Washington and southern British Columbia. Forearc Comparison of seismicity patterns with long-wavelength slab geometry and thermo-petrologic constraints sug- Serpentinization gests that seismicity occurrence in Cascadia is governed by an interplay between slab strain, metamorphic dehy- Eclogitization dration within the subducting oceanic plate, and a plate boundary seal that controls where fluids enter the Volcanism overriding plate. -
Geologic History of Siletzia, a Large Igneous Province in the Oregon And
Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Wells, R., Bukry, D., Friedman, R., Pyle, D., Duncan, R., Haeussler, P., & Wooden, J. (2014). Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot. Geosphere, 10 (4), 692-719. doi:10.1130/GES01018.1 10.1130/GES01018.1 Geological Society of America Version of Record http://cdss.library.oregonstate.edu/sa-termsofuse Downloaded from geosphere.gsapubs.org on September 10, 2014 Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Ray Wells1, David Bukry1, Richard Friedman2, Doug Pyle3, Robert Duncan4, Peter Haeussler5, and Joe Wooden6 1U.S. Geological Survey, 345 Middlefi eld Road, Menlo Park, California 94025-3561, USA 2Pacifi c Centre for Isotopic and Geochemical Research, Department of Earth, Ocean and Atmospheric Sciences, 6339 Stores Road, University of British Columbia, Vancouver, BC V6T 1Z4, Canada 3Department of Geology and Geophysics, University of Hawaii at Manoa, 1680 East West Road, Honolulu, Hawaii 96822, USA 4College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, Oregon 97331-5503, USA 5U.S. Geological Survey, 4210 University Drive, Anchorage, Alaska 99508-4626, USA 6School of Earth Sciences, Stanford University, 397 Panama Mall Mitchell Building 101, Stanford, California 94305-2210, USA ABSTRACT frames, the Yellowstone hotspot (YHS) is on southern Vancouver Island (Canada) to Rose- or near an inferred northeast-striking Kula- burg, Oregon (Fig. -
Washington Division of Geology and Earth Resources Open File Report 86-2, 34 P
COAL MATURATION AND THE NATURAL GAS POTENTIAL OF WESTERN AND CENTRAL WASHINGTON By TIMOTHY J. WALSH and WILLIAMS. LINGLEY, JR. WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES OPEN FILE REPORT 91-2 MARCH 1991 This report has not been edited or reviewed for conformity with Division of Geology and Earth Resources standards and nomenclature. ''llailal WASHINGTONNatural STATE Resources DEPARTMENT OF Brian Boyle ~ Comm1SSioner ol Public Lands Art Stearns Supervisor Division of Geology and Earth Resources Raymond Lasmanis. State Geologist CONTENTS Page Abstract ...................................................... 1 Introduction 1 Tertiary stratigraphy .............................................. 3 Structure as determined from mine maps ................................. 8 Thermal maturation as determined from coal data . 8 Timing of thermal maturation . 16 Mechanisms of heat flow . 17 Exploration significance ............................................ 17 Conclusions 19 References cited . 20 ILLUSTRATIONS Figure 1: Map showing distribution of Ulatisian and Narizian fluvial and deltaic rocks in western and central Washington . 2 Figure 2: Plot of porosity versus depth, selected wells, Puget and Columbia Basins 4 Figure 3: Correlation chart of Tertiary rocks and sediments of western and central Washington . 5 Figure 4: Isopach of Ulatisian and Narizian surface-accumulated rocks in western and central Washington . 7 Figure 5: Isorank contours plotted on structure contours, Wingate seam, Wilkeson-Carbonado coalfield, Pierce County . 9 Figure -
Volcanism and Igneous Intrusion
PNL-2882 UC-70 3 3679 00053 2145 .. ' Assessment of Effectiveness of Geologic Isolation Systems DISRUPTIVE EVENT ANALYSIS: VOLCANISM AND IGNEOUS INTRUSION B. M. Crowe Los Alamos Scientific. Laboratory August 1980 Prepared for the Office of Nuclear Waste Isolation under its Contract with the U.S. Department of Energy Pacific Northwest Laboratory Richland, Washington 99352 PREFACE Associated with commercial nuclear power production in the United States is the generation of potentially hazardous radioactive waste products. The Department of Energy (DOE), through the National Waste Terminal Storage (NWTS) Program and the Office of Nuclear Waste Isolation (ONWI), is seeking to develop nuclear waste isolation systems in geologic formations. These underground waste isolation systems will preclude contact with the biosphere of waste radionuclides in concentrations which are sufficient to cause deleterious impact on humans or their environments. Comprehensive analyses'of specific isolation systems are needed to assess the post-closure expectations of the systems. The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) .' Program has been established for developing the capability of making those analys;s! Among the analysis'required for the system evaluation is the detailed assessment of the post-closure performance of nuclear waste repositories in geologic formations. This assessment is concerned with aspects of the nuclear program which previously have not been addressed. The nature of the isolation systems (e.g., involving breach scenarios and transport through the geosphere) and the great length of time for which the wastes must be controlled dictate the development, demonstration, and application of novel assessment capabili ties. The assessment methodology must be thorough, flexible, objective, and scientifically defensible. -
OCR Document
AN INTRODUCTORY PROSPECTING MANUAL K N A O S I A T B N A O S N I I T K A F R Prepared by: J. R. Parker (Staff Geologist, Red Lake Resident Geologist Office, Ministry of Northern Development and Mines) Revised in 2004 and 2007 by: D. P. Parker and B. V. D'Silva (D'Silva Parker Associates) Discover Prospecting July 2007 Original Acknowledgments The author would like to thank K.G. Fenwick, Manager, Field Services Section (Northwest) and M.J. Lavigne, Resident Geologist, Thunder Bay, for initiating this prospecting manual project. Thanks also to the members of the Prospecting Manual Advisory Committee: P. Sangster, Staff Geologist, Timmins; M. Smyk, Staff Geologist, Schreiber-Hemlo; M. Garland, Regional Minerals Specialist, Thunder Bay; P. Hinz, Industrial Minerals Geologist, Thunder Bay; E. Freeman, Communications Project Officer, Toronto; R. Spooner, Mining Recorder, Red Lake; R. Keevil, Acting Staff Geologist, Dorset; and T. Saunders, President, N.W. Ontario Prospector's Association, Thunder Bay for their comments, input and advice. The author also thanks R. Spooner, Mining Recorder, Red Lake, for writing the text on the Mining Act in the "Acquiring Mining Lands" section of this manual. Thanks to B. Thompson, Regional Information Officer, Information and Media Section, Thunder Bay, for assistance in the preparation of slides and his advice on the presentation of the manual. Thanks also to B.T. Atkinson, Resident Geologist, Red Lake; H. Brown, Acting Staff Geologist, Red Lake; M. Garland, Regional Minerals Specialist, Thunder Bay; and M. Smyk, Staff Geologist, Schreiber-Hemlo for editing the manuscript of the manual. -
Controls on the Expression of Igneous Intrusions in Seismic Reflection Data GEOSPHERE; V
Research Paper GEOSPHERE Controls on the expression of igneous intrusions in seismic reflection data GEOSPHERE; v. 11, no. 4 Craig Magee, Shivani M. Maharaj, Thilo Wrona, and Christopher A.-L. Jackson Basins Research Group (BRG), Department of Earth Science and Engineering, Imperial College, 39 Prince Consort Road, London SW7 2BP, UK doi:10.1130/GES01150.1 14 figures; 2 tables ABSTRACT geometries in the field is, however, hampered by a lack of high-quality, fully CORRESPONDENCE: [email protected] three-dimensional (3-D) exposures and the 2-D nature of the Earth’s surface The architecture of subsurface magma plumbing systems influences a va- (Fig. 1). Geophysical techniques such as magnetotellurics, InSAR (interfero- CITATION: Magee, C., Maharaj, S.M., Wrona, T., riety of igneous processes, including the physiochemical evolution of magma metric synthetic aperture radar), and reflection seismology have therefore and Jackson, C.A.-L., 2015, Controls on the expres- sion of igneous intrusions in seismic reflection data: and extrusion sites. Seismic reflection data provides a unique opportunity to been employed to either constrain subsurface intrusions or track real-time Geosphere, v. 11, no. 4, p. 1024–1041, doi: 10 .1130 image and analyze these subvolcanic systems in three dimensions and has magma migration (e.g., Smallwood and Maresh, 2002; Wright et al., 2006; /GES01150.1. arguably revolutionized our understanding of magma emplacement. In par- Biggs et al., 2011; Pagli et al., 2012). Of these techniques, reflection seismol- ticular, the observation of (1) interconnected sills, (2) transgressive sill limbs, ogy arguably provides the most complete and detailed imaging of individual Received 11 November 2014 and (3) magma flow indicators in seismic data suggest that sill complexes intrusions and intrusion systems. -
Are Plutons Assembled Over Millions of Years by Amalgamation From
1996; Petford et al., 2000). If plutons are emplaced by bulk magmatic flow, then during emplacement, the magma must Are plutons assembled contain a melt fraction of at least 30–50 vol% (Vigneresse et al., 1996). At lower melt fractions, crystals in the melt are welded to their neighbors; thus, a low melt-fraction material over millions of years by probably is better regarded not as magma but as a solid with melt-filled pore spaces because bulk flow of such a material requires pervasive solid-state deformation. amalgamation from small The concept of plutons as large ascending molten blobs (Fig. 1) is widespread in geologic thought and commonly magma chambers? guides interpretation of field relations (e.g., Buddington, 1959; Miller et al., 1988; Clarke, 1992; Bateman, 1992; Miller and Paterson, 1999). A contrasting view is that diapiric as- Allen F. Glazner, Department of Geological Sciences, cent of magma is too slow and energetically inefficient to be CB#3315, University of North Carolina, Chapel Hill, North geologically important, and large magma bodies only form Carolina 27599, USA, [email protected] at the emplacement level where they are fed by dikes (e.g., John M. Bartley, Department of Geology and Geophysics, Clemens and Mawer, 1992; Petford et al., 2000). Several lines University of Utah, Salt Lake City, Utah 84112, USA of evidence indicate that, regardless of the ascent mechanism, Drew S. Coleman, Walt Gray*, and Ryan Z. Taylor*, at least some plutons were emplaced incrementally over time Department of Geological Sciences, CB#3315, University of spans an order of magnitude longer than the thermal lifetime North Carolina, Chapel Hill, North Carolina 27599, USA of a large magmatic mass (Coleman et al., 2004). -
Emplacement Mechanisms and Structural Influences of A
R-08-138 Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks – a principal study with application to the Götemar and Uthammar granites Site-descriptive modelling SDM-Site Laxemar Alexander R Cruden Department of Geology, University of Toronto December 2008 Svensk Kärnbränslehantering AB Swedish Nuclear Fuel and Waste Management Co Box 250, SE-101 24 Stockholm Phone +46 8 459 84 00 CM Gruppen AB, Bromma, 2009 ISSN 1402-3091 Tänd ett lager: SKB Rapport R-08-138 P, R eller TR. Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks – a principal study with application to the Götemar and Uthammar granites Site-descriptive modelling SDM-Site Laxemar Alexander R Cruden Department of Geology, University of Toronto December 2008 This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the author and do not necessarily coincide with those of the client. A pdf version of this document can be downloaded from www.skb.se Abstract The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86–1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Götemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. -
Cascadia Low Frequency Earthquakes at the Base of an Overpressured Subduction Shear Zone ✉ Andrew J
ARTICLE https://doi.org/10.1038/s41467-020-17609-3 OPEN Cascadia low frequency earthquakes at the base of an overpressured subduction shear zone ✉ Andrew J. Calvert 1 , Michael G. Bostock 2, Geneviève Savard 3 & Martyn J. Unsworth4 In subduction zones, landward dipping regions of low shear wave velocity and elevated Poisson’s ratio, which can extend to at least 120 km depth, are interpreted to be all or part of the subducting igneous oceanic crust. This crust is considered to be overpressured, because fl 1234567890():,; uids within it are trapped beneath an impermeable seal along the overlying inter-plate boundary. Here we show that during slow slip on the plate boundary beneath southern Vancouver Island, low frequency earthquakes occur immediately below both the landward dipping region of high Poisson’s ratio and a 6–10 km thick shear zone revealed by seismic reflections. The plate boundary here either corresponds to the low frequency earthquakes or to the anomalous elastic properties in the lower 3–5 km of the shear zone immediately above them. This zone of high Poisson’s ratio, which approximately coincides with an electrically conductive layer, can be explained by slab-derived fluids trapped at near-lithostatic pore pressures. 1 Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. 2 Department of Earth, Ocean and Atmospheric Sciences, 2207 Main Mall, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. 3 Department of Geosciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada. 4 Department of Physics, University of Alberta, Edmonton, AB T6G 2E9, Canada. -
Magmatism and Metamorphism in the Leech River Complex
MAGMATISM AND METAMORPHISM IN THE LEECH RIVER COMPLEX, SOUTHERN VANCOUVER ISLAND, BRITISH COLUMBIA, CANADA - IMPLICATIONS FOR EOCENE TECTONICS OF THE PAClFlC NORTHWEST by Wesley Glen Groome, B.Sc. .University of Alberta, 1998 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the OEPARTMENT OF EARTH SCIENCES, SIMON FRASER UNIVERSITY, Bumaby, BC Q Wesley Glen Groome 2000 SIMON FRASER UNIVERSITY May 2000 All rights reserved. This work may not be reproduced in Mole or in part, by photocopy or other means, without the permission of the author. The aidhar has granted a ncm- L'auteur a accordé une licence non exciusive licence allowing the exclusive permettant B la National hiof Canada to Bbiiothéque nationaie du Canada de reproduce, loan, distribute or seiî reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendce des copies de cette thèse sous paper or electrdc farmats. la fmede microfichelfilm, de reproduction sur papier ou sur foxmat électronique. The author retains ownership of the L'auteur comme la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor subsîantial extracts fbm it Ni la îhèse ni des extraits substantiels may be printed or othdse de celle-ci ne doivent être imprimés reproduced without the auîhor's ou autrement reprodrnts sans son permission. autorisation. ABSTRACT The Leech River Complex of southem Vancouver Island consists of the Leech River Schist and Mesozoic and Eocene deformed igneous rocks. In the study area, the igneous rocks consist of the Walker Creek intrusions, and two previously unrecognized intrusive un&, the Tnpp Creek metabasite and the Jordan River metagranodiorite. -
How Is Radon Related to Rocks, Soils, and Uranium?
Earth Science Unit Radon Alert TEACHER'S NOTES 1 HOW IS RADON RELATED TO ROCKS, SOILS, AND URANIUM? BACKGROUND In preparation for this lesson, students should have basic knowledge of: • three basic rock types • difference between rocks and minerals • rock formation processes • movement of geologic materials in groundwater. Rocks are the solid materials, or building blocks, that make up the earth’s crust. Each rock is made up of one or more different minerals. For example, granite might be composed of the minerals quartz, orthoclase feldspar, mica, and hornblende. Limestone is an example of a rock that consists of only one kind of mineral: calcite. Although there are 2000 or more kinds of minerals in the earth, only about a dozen or so are common. These include plagioclase feldspar, orthoclase feldspar, quartz, augite, hornblende, and mica. Each rock type varies somewhat in its mineral content. All granites, for example, contain quartz and feldspar; these are essential minerals in granite. Granite may or may not contain hornblende, an accessory mineral in granite. Furthermore, the proportions of the different minerals can vary from sample to sample. Thus, granites can be different colors. Those high in quartz and feldspar tend to be lighter in color. Those containing greater amounts of darker minerals, like biotite mica, will be darker in color. Igneous rocks that harden from magma under the surface are called intrusive rocks. Those that form by hardening of lava above ground are called extrusive, or volcanic. Intrusive and extrusive igneous rocks differ in texture, which is determined by the size and arrangement of the mineral crystals in the rock. -
Impact from a Nearby Seismically-Active Fault To
IMPACT FROM A NEARBY SEISMICALLY-ACTIVE FAULT TO SEISMIC HAZARD IN VICTORIA, CANADA JACOB KUKOVICA, SHERI MOLNAR, HADI GHOFRANI & KAREN ASSATOURIANS Department of Earth Sciences, University of Western Ontario, Canada DISCLAIMER - ERRATUM The description of the Leech River fault (LRF) and the probabilistic seismic hazard analyses (PSHA) presented in this paper were preliminary findings. The LRF has been proven to be seismically inactive in multiple research papers (Morell et al. 2017; 2018, Li et al., 2018) and was erroneously presented as seismically active here. Rather, an area of high-angle transpressional faulting within the Leech River Valley, referred to as the Leech River Valley fault zone (LRVFZ), is the source of seismic activity (Kukovica et al., 2019). The introduced active LRF here should be considered as the LRVFZ. The geometry of the introduced active fault zone does not change. PSHA in this paper utilized two different sets of ground motion prediction equations (GMPEs) to characterize the seismicity of the LRVFZ with fault source zone GMPEs suggesting the LRVFZ increases the Victoria hazard by a factor of 2.65. This estimation is greatly overpredicted due to an error in the input file for the EQHAZ software. The total number of entry points used to describe the fault source zone GMPEs exceeded the coded limit allowed for EQHAZ. Therefore, the presented results for the fault source zone GMPEs in Table 1 and Figure 3 do not accurately represent the total increase in hazard due to the LRVFZ. Accurate simulations of the LRVFZ with fault source zone GMPEs increase the pseudo-spectral accelerations (PSA) at Victoria on average by 11% at 10 Hz and 9% for PGA (Kukovica et al., 2019).