Tectonic Imbrication and Foredeep Development in the Penokean
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Linking Megathrust Earthquakes to Brittle Deformation in a Fossil Accretionary Complex
ARTICLE Received 9 Dec 2014 | Accepted 13 May 2015 | Published 24 Jun 2015 DOI: 10.1038/ncomms8504 OPEN Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex Armin Dielforder1, Hauke Vollstaedt1,2, Torsten Vennemann3, Alfons Berger1 & Marco Herwegh1 Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. 1 Institute of Geological Sciences, University of Bern, Baltzerstrasse 1 þ 3, Bern CH-3012, Switzerland. 2 Center for Space and Habitability, University of Bern, Sidlerstrasse 5, Bern CH-3012, Switzerland. 3 Institute of Earth Surface Dynamics, University of Lausanne, Geˆopolis 4634, Lausanne CH-1015, Switzerland. Correspondence and requests for materials should be addressed to A.D. (email: [email protected]). NATURE COMMUNICATIONS | 6:7504 | DOI: 10.1038/ncomms8504 | www.nature.com/naturecommunications 1 & 2015 Macmillan Publishers Limited. -
Strike and Dip Refer to the Orientation Or Attitude of a Geologic Feature. The
Name__________________________________ 89.325 – Geology for Engineers Faults, Folds, Outcrop Patterns and Geologic Maps I. Properties of Earth Materials When rocks are subjected to differential stress the resulting build-up in strain can cause deformation. Depending on the material properties the result can either be elastic deformation which can ultimately lead to the breaking of the rock material (faults) or ductile deformation which can lead to the development of folds. In this exercise we will look at the various types of deformation and how geologists use geologic maps to understand this deformation. II. Strike and Dip Strike and dip refer to the orientation or attitude of a geologic feature. The strike line of a bed, fault, or other planar feature, is a line representing the intersection of that feature with a horizontal plane. On a geologic map, this is represented with a short straight line segment oriented parallel to the strike line. Strike (or strike angle) can be given as either a quadrant compass bearing of the strike line (N25°E for example) or in terms of east or west of true north or south, a single three digit number representing the azimuth, where the lower number is usually given (where the example of N25°E would simply be 025), or the azimuth number followed by the degree sign (example of N25°E would be 025°). The dip gives the steepest angle of descent of a tilted bed or feature relative to a horizontal plane, and is given by the number (0°-90°) as well as a letter (N, S, E, W) with rough direction in which the bed is dipping. -
Potential Capacity for Geologic Carbon Sequestration in the Midcontinent Rift System in Minnesota
MINNESOTA GEOLOGICAL SURVEY Harvey Thorleifson, Director POTENTIAL CAPACITY FOR GEOLOGIC CARBON SEQUESTRATION IN THE MIDCONTINENT RIFT SYSTEM IN MINNESOTA L. Harvey Thorleifson, Minnesota Geological Survey, Editor A report prepared in fulfillment of the requirements of Minnesota Legislative Session 85 Bill S. F. 2096 Minnesota Geological Survey Open File Report OFR-08-01 University of Minnesota Saint Paul – 2008 Cover figure credit: Iowa Geological Survey 2 POTENTIAL CAPACITY FOR GEOLOGIC CARBON SEQUESTRATION IN THE MIDCONTINENT RIFT SYSTEM IN MINNESOTA 3 This open file is accessible from the web site of the Minnesota Geological Survey (http://www.geo.umn.edu/mgs/) as a PDF file readable with Acrobat Reader. Date of release: 24 January 2008 Recommended citation Thorleifson, L. H., ed., 2008, Potential capacity for geologic carbon sequestration in the Midcontinent Rift System in Minnesota, Minnesota Geological Survey Open File Report OFR-08-01, 138 p Minnesota Geological Survey 2642 University Ave West Saint Paul, Minnesota 55114-1057 Telephone: 612-627-4780 Fax: 612-627-4778 Email address: [email protected] Web site: http://www.geo.umn.edu/mgs/ ©2008 by the Regents of the University of Minnesota All rights reserved The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, color, creed, religion, national origin, sex, age, marital status, disability, public assistance status, veteran status, or sexual orientation. 4 CONTENTS EXECUTIVE SUMMARY L. H. Thorleifson . 7 INTRODUCTION L. H. Thorleifson . 11 CLIMATE CHANGE L. H. Thorleifson . 11 Introduction . 11 Intergovernmental Panel on Climate Change (IPCC) . -
U–Pb Zircon (SHRIMP) Ages for the Lebombo Rhyolites, South Africa
Journal of the Geological Society, London, Vol. 161, 2004, pp. 547–550. Printed in Great Britain. 2000) and the ages corroborate and further strengthen the SPECIAL chronology of the Lebombo stratigraphy. The rapid eruption of the Karoo succession is thought to have been responsible for trigger- U–Pb zircon (SHRIMP) ing the early Toarcian extinction event (Hesselbo et al. 2000). Geological setting. The Karoo Supergroup succession along the ages for the Lebombo Lebombo monocline is highlighted in Figure 1. The oldest phase of Karoo volcanism is marked by the Mashikiri nephelinites, rhyolites, South Africa: which unconformably overlie Jurassic Clarens Formation sand- stones (Fig. 2). The nephelinites have been dated at 182.1 Æ refining the duration of 1.6 Ma (40Ar/39Ar plateau age; Duncan et al. 1997) and form a lava succession up to 170 m thick (Bristow 1984). These rocks Karoo volcanism are confined to the northern part of the Lebombo rift and are absent along the central and southern sections. The nephelinites T. R. RILEY1,I.L.MILLAR2, are conformably overlain by picrites and picritic basalts of the 3 1 Letaba Formation, although in the southern Lebombo the picrites M. K. WATKEYS ,M.L.CURTIS, directly overlie the Clarens Formation. The picrites overlap in 1 3 P. T. LEAT , M. B. KLAUSEN & age (182.7 Æ 0.8 Ma; Duncan et al. 1997) with the Mashikiri C. M. FANNING4 nephelinites and are believed to form a succession up to 4 km in thickness. 1British Antarctic Survey, High Cross, Madingley Road, The Letaba Formation picrites are in turn overlain by a major Cambridge, CB3 0ET, UK (e-mail: [email protected]) succession (4–5 km thick) of low-MgO basalts, termed the Sabie 2British Antarctic Survey c/o NERC Isotope Geosciences River Basalt Formation (Cleverly & Bristow 1979). -
Significance of Brittle Deformation in the Footwall
Journal of Structural Geology 64 (2014) 79e98 Contents lists available at SciVerse ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg Significance of brittle deformation in the footwall of the Alpine Fault, New Zealand: Smithy Creek Fault zone J.-E. Lund Snee a,*,1, V.G. Toy a, K. Gessner b a Geology Department, University of Otago, PO Box 56, Dunedin 9016, New Zealand b Western Australian Geothermal Centre of Excellence, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia article info abstract Article history: The Smithy Creek Fault represents a rare exposure of a brittle fault zone within Australian Plate rocks that Received 28 January 2013 constitute the footwall of the Alpine Fault zone in Westland, New Zealand. Outcrop mapping and Received in revised form paleostress analysis of the Smithy Creek Fault were conducted to characterize deformation and miner- 22 May 2013 alization in the footwall of the nearby Alpine Fault, and the timing of these processes relative to the Accepted 4 June 2013 modern tectonic regime. While unfavorably oriented, the dextral oblique Smithy Creek thrust has Available online 18 June 2013 kinematics compatible with slip in the current stress regime and offsets a basement unconformity beneath Holocene glaciofluvial sediments. A greater than 100 m wide damage zone and more than 8 m Keywords: Fault zone wide, extensively fractured fault core are consistent with total displacement on the kilometer scale. e Fluid flow Based on our observations we propose that an asymmetric damage zone containing quartz carbonate Hydrofracture echloriteeepidote veins is focused in the footwall. -
Timeline of Natural History
Timeline of natural history This timeline of natural history summarizes significant geological and Life timeline Ice Ages biological events from the formation of the 0 — Primates Quater nary Flowers ←Earliest apes Earth to the arrival of modern humans. P Birds h Mammals – Plants Dinosaurs Times are listed in millions of years, or Karo o a n ← Andean Tetrapoda megaanni (Ma). -50 0 — e Arthropods Molluscs r ←Cambrian explosion o ← Cryoge nian Ediacara biota – z ←Earliest animals o ←Earliest plants i Multicellular -1000 — c Contents life ←Sexual reproduction Dating of the Geologic record – P r The earliest Solar System -1500 — o t Precambrian Supereon – e r Eukaryotes Hadean Eon o -2000 — z o Archean Eon i Huron ian – c Eoarchean Era ←Oxygen crisis Paleoarchean Era -2500 — ←Atmospheric oxygen Mesoarchean Era – Photosynthesis Neoarchean Era Pong ola Proterozoic Eon -3000 — A r Paleoproterozoic Era c – h Siderian Period e a Rhyacian Period -3500 — n ←Earliest oxygen Orosirian Period Single-celled – life Statherian Period -4000 — ←Earliest life Mesoproterozoic Era H Calymmian Period a water – d e Ectasian Period a ←Earliest water Stenian Period -4500 — n ←Earth (−4540) (million years ago) Clickable Neoproterozoic Era ( Tonian Period Cryogenian Period Ediacaran Period Phanerozoic Eon Paleozoic Era Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Permian Period Mesozoic Era Triassic Period Jurassic Period Cretaceous Period Cenozoic Era Paleogene Period Neogene Period Quaternary Period Etymology of period names References See also External links Dating of the Geologic record The Geologic record is the strata (layers) of rock in the planet's crust and the science of geology is much concerned with the age and origin of all rocks to determine the history and formation of Earth and to understand the forces that have acted upon it. -
Midcontinent Rift
VOL. 97 NO. 18 15 SEP 2016 NORTH AMERICA’S MIDCONTINENT RIFT Augmented Reality for Earth Science Quirky Geoscience Tunes Future of AGU Meetings NEW in Fall 2016 GeoHealth will foster the intersection of Earth science disciplines (Earth processes, climate change, atmospheric and ocean sciences, hydrology, among others), with those of the health sciences, defined broadly (environmental and ecosystem health and services, human and agricultural health, geomedicine, and the impact of natural hazards). Now Accepting Applications for Two Editors in Chief of GeoHealth AGU is launching GeoHealth under Founding Editor Rita R. Colwell. We are seeking applications for two dynamic, well-organized scientists with high editorial standards and strong leadership skills to serve 4-year terms as the editors in chief (EICs) to lead this exciting journal starting in 2017 and beyond. One editor’s main area of focus will be on the geosciences, while the other editor’s main area of focus will be on health. This is an important opportunity to help shape and lead this increasingly important, cross-cutting discipline. The EICs will be the principal architects of the scientific content of the journal. They are active scientists, well-known and well-regarded in their respective discipline. The EICs must be active in soliciting the best science from the best scientists to be published in the journal. Working with the other editors and AGU staff, EICs are the arbiter of the content of the journal. Among other functions, EICs will be responsible for: • Acting as an ambassador to the author/editor/reviewer/scientist community. • Setting the strategy for the journal. -
Wakabayashi Intgeolr
International Geology Review ISSN: 0020-6814 (Print) 1938-2839 (Online) Journal homepage: http://www.tandfonline.com/loi/tigr20 Whither the megathrust? Localization of large- scale subduction slip along the contact of a mélange John Wakabayashi & Christie D. Rowe To cite this article: John Wakabayashi & Christie D. Rowe (2015) Whither the megathrust? Localization of large-scale subduction slip along the contact of a mélange, International Geology Review, 57:5-8, 854-870, DOI: 10.1080/00206814.2015.1020453 To link to this article: http://dx.doi.org/10.1080/00206814.2015.1020453 Published online: 09 Mar 2015. Submit your article to this journal Article views: 189 View related articles View Crossmark data Citing articles: 1 View citing articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tigr20 Download by: [University of California, Berkeley] Date: 04 April 2016, At: 09:19 International Geology Review, 2015 Vol. 57, Nos. 5–8, 854–870, http://dx.doi.org/10.1080/00206814.2015.1020453 Whither the megathrust? Localization of large-scale subduction slip along the contact of a mélange John Wakabayashia* and Christie D. Roweb aDepartment of Earth and Environmental Sciences, California State University, Fresno, CA, USA; bDepartment of Earth and Planetary Sciences, McGill University, Montreal, Canada (Received 13 February 2015; accepted 14 February 2015) Long-lived subduction complexes, such as the Franciscan Complex of California, include tectonic contacts that represent exhumed megathrust horizons that collectively accommodated thousands of kilometres of slip. The chaotic nature of mélanges in subduction complexes has spawned proposals that these mélanges form as a result of megathrust displacement. -
UC Riverside UC Riverside Electronic Theses and Dissertations
UC Riverside UC Riverside Electronic Theses and Dissertations Title Exploring the Texture of Ocean-Atmosphere Redox Evolution on the Early Earth Permalink https://escholarship.org/uc/item/9v96g1j5 Author Reinhard, Christopher Thomas Publication Date 2012 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA RIVERSIDE Exploring the Texture of Ocean-Atmosphere Redox Evolution on the Early Earth A Dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Geological Sciences by Christopher Thomas Reinhard September 2012 Dissertation Committee: Dr. Timothy W. Lyons, Chairperson Dr. Gordon D. Love Dr. Nigel C. Hughes ! Copyright by Christopher Thomas Reinhard 2012 ! ! The Dissertation of Christopher Thomas Reinhard is approved: ________________________________________________ ________________________________________________ ________________________________________________ Committee Chairperson University of California, Riverside ! ! ACKNOWLEDGEMENTS It goes without saying (but I’ll say it anyway…) that things like this are never done in a vacuum. Not that I’ve invented cold fusion here, but it was quite a bit of work nonetheless and to say that my zest for the enterprise waned at times would be to put it euphemistically. As it happens, though, I’ve been fortunate enough to be surrounded these last years by an incredible group of people. To those that I consider scientific and professional mentors that have kept me interested, grounded, and challenged – most notably Tim Lyons, Rob Raiswell, Gordon Love, and Nigel Hughes – thank you for all that you do. I also owe Nigel and Mary Droser a particular debt of graditude for letting me flounder a bit my first year at UCR, being understanding and supportive, and encouraging me to start down the road to where I’ve ended up (for better or worse). -
Detrital Zircon Provenance and Lithofacies Associations Of
geosciences Article Detrital Zircon Provenance and Lithofacies Associations of Montmorillonitic Sands in the Maastrichtian Ripley Formation: Implications for Mississippi Embayment Paleodrainage Patterns and Paleogeography Jennifer N. Gifford 1,*, Elizabeth J. Vitale 1, Brian F. Platt 1 , David H. Malone 2 and Inoka H. Widanagamage 1 1 Department of Geology and Geological Engineering, University of Mississippi, Oxford, MS 38677, USA; [email protected] (E.J.V.); [email protected] (B.F.P.); [email protected] (I.H.W.) 2 Department of Geography, Geology, and the Environment, Illinois State University, Normal, IL 61790, USA; [email protected] * Correspondence: jngiff[email protected]; Tel.: +1-(662)-915-2079 Received: 17 January 2020; Accepted: 15 February 2020; Published: 22 February 2020 Abstract: We provide new detrital zircon evidence to support a Maastrichtian age for the establishment of the present-day Mississippi River drainage system. Fieldwork conducted in Pontotoc County,Mississippi, targeted two sites containing montmorillonitic sand in the Maastrichtian Ripley Formation. U-Pb detrital zircon (DZ) ages from these sands (n = 649) ranged from Mesoarchean (~2870 Ma) to Pennsylvanian (~305 Ma) and contained ~91% Appalachian-derived grains, including Appalachian–Ouachita, Gondwanan Terranes, and Grenville source terranes. Other minor source regions include the Mid-Continent Granite–Rhyolite Province, Yavapai–Mazatzal, Trans-Hudson/Penokean, and Superior. This indicates that sediment sourced from the Appalachian Foreland Basin (with very minor input from a northern or northwestern source) was being routed through the Mississippi Embayment (MSE) in the Maastrichtian. We recognize six lithofacies in the field areas interpreted as barrier island to shelf environments. Statistically significant differences between DZ populations and clay mineralogy from both sites indicate that two distinct fluvial systems emptied into a shared back-barrier setting, which experienced volcanic ash input. -
The Geology of the Middle Precambrian Rove Formation in Northeastern Minnesota
MINNESOTA GEOLOGICAL SURVEY 5 P -7 Special Publication Series The Geology of the Middle Precambrian Rove Formation in northeastern Minnesota G. B. Morey UNIVERSITY OF MINNESOTA MINNEAPOLIS • 1969 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I THE GEOLOGY OF THE MIDDLE PRECAMBRIAN ROVE FORMATION IN NORTHEASTERN MINNESOTA by G. B. Morey CONTENTS Page Abstract ........................................... 1 Introduction. 3 Location and scope of study. 3 Acknowledgements .. 3 Regional geology . 5 Structural geology . 8 Rock nomenclature . 8 Stratigraphy . .. 11 Introduction . .. 11 Nomenclature and correlation. .. 11 Type section . .. 11 Thickness . .. .. 14 Lower argillite unit. .. 16 Definition, distribution, and thickness. .. 16 Lithologic character . .. 16 Limestones. .. 17 Concretions. .. 17 Transition unit . .. 17 Definition, distribution, and thickness. .. 17 Lithologic character . .. 19 Thin-bedded graywacke unit . .. 19 Definition, distribution, and thickness. .. 19 Lithologic character. .. 20 Concretions ... .. 20 Sedimentary structures. .. 22 Internal bedding structures. .. 22 Structureless bedding . .. 23 Laminated bedding . .. 23 Graded bedding. .. 23 Cross-bedding . .. 25 Convolute bedding. .. 26 Internal bedding sequences . .. 26 Post-deposition soft sediment deformation structures. .. 27 Bed pull-aparts . .. 27 Clastic dikes . .. 27 Load pockets .. .. 28 Flame structures . .. 28 Overfolds . .. 28 Microfaults. .. 28 Ripple marks .................................. 28 Sole marks . .. 28 Groove casts . .. 30 Flute casts . -
Cyanobacterial Evolution During the Precambrian
International Journal of Astrobiology 15 (3): 187–204 (2016) doi:10.1017/S1473550415000579 © Cambridge University Press 2016 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Cyanobacterial evolution during the Precambrian Bettina E. Schirrmeister1, Patricia Sanchez-Baracaldo2 and David Wacey1,3 1School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK e-mail: [email protected] 2School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK 3Centre for Microscopy, Characterisation and Analysis, and ARC Centre of Excellence for Core to Crust Fluid Systems, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Abstract: Life on Earth has existed for at least 3.5 billion years. Yet, relatively little is known of its evolution during the first two billion years, due to the scarceness and generally poor preservation of fossilized biological material. Cyanobacteria, formerly known as blue green algae were among the first crown Eubacteria to evolve and for more than 2.5 billion years they have strongly influenced Earth’s biosphere. Being the only organism where oxygenic photosynthesis has originated, they have oxygenated Earth’s atmosphere and hydrosphere, triggered the evolution of plants –being ancestral to chloroplasts– and enabled the evolution of complex life based on aerobic respiration. Having such a strong impact on early life, one might expect that the evolutionary success of this group may also have triggered further biosphere changes during early Earth history.