DOCSLIB.ORG

Basement Structure and Styles of Active Tectonic Deformation in Central Interior Alaska

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Basement Structure and Styles of Active Tectonic Deformation in Central Interior Alaska geosciences Article Basement Structure and Styles of Active Tectonic Deformation in Central Interior Alaska Nilesh C. Dixit 1,* and Catherine Hanks 2 1 Department of Physics, Geology and Engineering Technology, Northern Kentucky University, Nunn Drive, Highland Heights, KY 41099, USA 2 Department of Geosciences, University of Alaska Fairbanks, 900 Yukon Drive, Fairbanks, AK 99775, USA; [email protected] * Correspondence: [email protected] Abstract: Central Interior Alaska is one of the most seismically active regions in North America, exhibiting a high concentration of intraplate earthquakes approximately 700 km away from the southern Alaska subduction zone. Seismological evidence suggests that intraplate seismicity in the region is not uniformly distributed, but concentrated in several discrete seismic zones, including the Nenana basin and the adjacent Tanana basin. Although the location and magnitude of the seismic activity in both basins are well defined by a network of seismic stations in the region, the tectonic controls on these intraplate earthquakes and the heterogeneous nature of Alaska’s continental interior remain poorly understood. We investigated the crustal structure of the Nenana and Tanana basins using available seismic reflection, aeromagnetic and gravity anomaly data, supplemented by geophysical well logs and outcrop data. We developed nine new two-dimensional forward models to delineate internal geometries and the crustal structure of Alaska’s interior. The results of our study demonstrates a strong crustal heterogeneity beneath both basins. The Tanana basin is a relatively Citation: Dixit, N.C.; Hanks, C. shallow (up to 2 km) asymmetrical foreland basin with its southern, deeper side controlled by the Basement Structure and Styles of Active Tectonic Deformation in northern foothills of the Central Alaska Range. Northeast-trending left lateral strike-slip faults within Central Interior Alaska. Geosciences the Tanana basin are interpreted as a zone of clockwise crustal block rotation. The Nenana basin 2021, 11, 127. https://doi.org/ has a fundamentally different geometry. It is a deep (up to 8 km), narrow transtensional pull-apart 10.3390/geosciences11030127 basin that is deforming along the left-lateral Minto Fault. This study identifies two distinct modes of current tectonic deformation in Central Interior Alaska and provides a basis for modeling the Academic Editors: interplay between intraplate stress fields and major structural features that potentially influence the Jesus Martinez-Frias and Lev generation of intraplate earthquakes in the region. V. Eppelbaum Keywords: potential field modeling; interior Alaska; transtensional basin; foreland basin; Received: 15 January 2021 seismic interpretation Accepted: 24 February 2021 Published: 10 March 2021 Publisher’s Note: MDPI stays neutral 1. Introduction with regard to jurisdictional claims in published maps and institutional affil- The observed occurrence of intraplate earthquakes within a rigid continental interior iations. provides direct evidence of localized zones of high strain concentration hundreds of kilometers away from the plate boundary. Although such events account for less than 10 percent of all global earthquakes and release only 5 percent of the global seismic energy, they can inflict heavy damage to human lives and property in the region [1]. From a plate tectonics view, intraplate earthquakes provide important information about the rheology Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. of the lithosphere and tectonic forces and stresses operating within the lithosphere [2,3]. This article is an open access article Investigating relationships among lithospheric strength, tectonic stresses, and intraplate distributed under the terms and seismicity can significantly improve our knowledge of intraplate dynamics, which would conditions of the Creative Commons allow us to accurately perform seismic hazard assessment in an intraplate setting. Attribution (CC BY) license (https:// Central Interior Alaska is one of the most seismically active intraplate regions in creativecommons.org/licenses/by/ the North America. In the past, this region has experienced significant seismic activity, 4.0/). including large-scale earthquakes as high as Mw 7.9. Examples include 2002 Mw 7.9 Denali Geosciences 2021, 11, 127. https://doi.org/10.3390/geosciences11030127 https://www.mdpi.com/journal/geosciences Geosciences 2021, 11, 127 2 of 30 Central Interior Alaska is one of the most seismically active intraplate regions in the Geosciences 2021, 11, 127 North America. In the past, this region has experienced significant seismic activity,2 of 25 in- cluding large-scale earthquakes as high as Mw 7.9. Examples include 2002 Mw 7.9 Denali Fault earthquake; 1967 Mw 5-6 Fairbanks earthquake; 1937 Mw 7.3 Salcha earthquake; 1947Fault Mw earthquake; 7.2 earthquake 1967 Mw in 5-6 the Fairbanks northern earthquake; foothills 1937of the Mw Alaska 7.3 Salcha Range earthquake; [4–6] (Figure 1947 1). BasedMw on 7.2 earthquakeincreasing inseismological the northern foothillsevidence, of intraplate the Alaska Rangeseismicity [4–6 ]in (Figure the Central1). Based Alaska regionon increasing appears seismologicalto not be uniformly evidence, distributed, intraplateseismicity but concentrated in the Central in several Alaska discrete region seis- micappears zones to(Figure not be 1). uniformly The location distributed, and magnitud but concentratede of the in seismic several activity discrete seismicin Central zones Alaska is well(Figure defined1). The by location a network and magnitude of seismic ofstations the seismic in the activity region. in However, Central Alaska the tectonic is well con- defined by a network of seismic stations in the region. However, the tectonic controls on trols on intraplate earthquakes and the heterogeneous nature of the continental litho- intraplate earthquakes and the heterogeneous nature of the continental lithosphere remain spherepoorly remain understood. poorly A understood. detailed knowledge A detailed of the knowledge crustal structure of the beneath crustal Central structure Alaska beneath Centralprovince Alaska is critical province to help is testcritical various to help tectonic test models various explaining tectonic themodels interplay explaining between the in- terplaythe intraplate between stress the fieldsintraplate causing stress earthquakes fields causing and the earthquakes development ofand regional the development structural of regionalfeatures structural in this region. features in this region. FigureFigure 1. Simplified 1. Simplified tectonic tectonic map map of ofcentral central Alaska Alaska showing showing the locationlocation of of the the study study area area relative relative to major to major active active tectonic tectonic featuresfeatures and the and major the major active active faults faults in inth thee region region [7–10]. [7–10]. Red box indicatesindicates the the position position of Figureof Figure 2. The 2. The Minto Minto Flats Flats Seismic Seismic Zone Zone(MFSZ), (MFSZ), the Fairbanks the Fairbanks Seismic Seismic Zone Zone (FSZ), (FSZ), and and the SalchaSeismic Seismic Zone Zone (SSZ). (SSZ The). The horizontal horizontal velocity velocity vectors vectors are are measuredmeasured relative relative to the to thestable stable North North American American craton craton and areare inferredinferred from from the the GPS GPS velocities velociti calculatedes calculated for the for region the region by Fletcherby Fletcher [5]. Focal [5]. Focal mechanism mechanism solutions solutions of of notable notable earthq earthquakesuakes inin interior interior Alaska Alaska indicate indicate N–S N–S directed directed compressive compressive stressesstresses in response in response to the to theplate plate subduction subduction along along the the southe southernrn marginmargin of of Alaska Alaska [4, 6[4,6,11].,11]. The The blue blue solid solid line marksline marks the the flat-slabflat-slab region region showing showing the the subducted subducted ex extenttent of of the the Yakutat microplate microplate [6 ].[6]. In Inthis this study, study, integrated integrated geophysicalgeophysical investigations investigations were were carried carried out toout image to image the the subsurface structures, basement depth, and formation boundaries to construct new crustal subsurface structures, basement depth, and formation boundaries to construct new crus- scale models for the Central Alaska province. The structure of the upper crust was defined tal byscale integrating models gravityfor the andCentral magnetic Alaska field province. data with The newly structure obtained of industrythe upper seismic crust was definedreflection by integrating profiles, geophysical gravity and logs, magnetic and outcrop field data. data The with models newly presented obtained in this industry paper seis- michelp reflection to constrain profiles, the basin geophysical geometries, logs, define and major outcrop boundaries data. The between models the sedimentarypresented in this paperand help underlying to constrain heterogeneous the basin basement geometries units,, define identify major the possible boundaries location between of intrusive the sedi- mentary and underlying heterogeneous basement units, identify the possible location of Geosciences 2021, 11, 127 3 of 25 bodies, and identify possible active geologic structures responsible for the ongoing crustal deformation in the region. Our results show that the Cenozoic sedimentary basins that
Load more

Recommended publications
  • Preliminary Catalog of the Sedimentary Basins of the United States
    Preliminary Catalog of the Sedimentary Basins of the United States By James L. Coleman, Jr., and Steven M. Cahan Open-File Report 2012–1111 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Coleman, J.L., Jr., and Cahan, S.M., 2012, Preliminary catalog of the sedimentary basins of the United States: U.S. Geological Survey Open-File Report 2012–1111, 27 p. (plus 4 figures and 1 table available as separate files) Available online at http://pubs.usgs.gov/of/2012/1111/. iii Contents Abstract ...........................................................................................................................................................1
    [Show full text]
  • Tectonics and Sedimentation in Foreland Basins: Results from the Integrated Basin Studies Project
    Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021 Tectonics and sedimentation in foreland basins: results from the Integrated Basin Studies project ALAIN MASCLE 1 & CAI PUIGDEFABREGAS 2,3 IIFP School, 228-232 avenue Napoldon Bonaparte, 92852 Rueil-Malmaison Cedex, France (e-mail: [email protected]) 2Norsk Hydro Research Centre, Bergen, Norway. 3Institut de Ciences de la Terra, (?SIC, Barcelona, Spain. Why foreland basins? to a better understanding of some basic interact- ing tectonic, sedimentary and hydrologic pro- Over the last ten years or so, since the Fribourg cesses (More & Vrolijk 1992; Touret & van meeting in 1985 (Homewood et al. 1986), the Hinte 1992). Additional data have also been attention given by sedimentologists and struc- obtained through the development of analogue tural geologists to the geology of foreland basins and numerical models (Larroque et al. 1992; has been growing continuously, parallel to the Zoetemeijer 1993). The physical parameters increase of co-operative links between scientists controlling the forward propagation of d6colle- from the two disciplines. A number of reasons ments and thrusts (fluid pressure, roughness, lie behind this development. Attempting to sediment thickness, etc.) have been determined understand the growth of an orogen without and tested. The relationships between rapidly paying due attention to the stratigraphic record subsiding piggyback basins and growing ramp of the derived sediments would be unrealistic. It anticlines have also been imaged, although the would, moreover, be equally unrealistic to con- lack of deep-sea well control still prevents accu- struct restored sections across the chain without rate sedimentological studies. More significant considering the constraints imposed by the has been the progress in our understanding of basin-fill architecture, or to describe the basin- the role of fluids and pore pressure in the fill evolution disregarding the development of development of thrust belts.
    [Show full text]
  • 38. Structural and Stratigraphic Evolution of the Sumisu Rift, Izu-Bonin Arc1
    Taylor, B., Fujioka, K., et al., 1992 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 126 38. STRUCTURAL AND STRATIGRAPHIC EVOLUTION OF THE SUMISU RIFT, IZU-BONIN ARC1 Adam Klaus,2,3 Brian Taylor,2 Gregory F. Moore,2 Mary E. MacKay,2 Glenn R. Brown,4 Yukinobu Okamura,5 and Fumitoshi Murakami5 ABSTRACT The Sumisu Rift, which is ~ 120 km long and 30-50 km wide, is bounded to the north and south by structural and volcanic highs west of the Sumisu and Torishima calderas and longitudinally by curvilinear border fault zones with both convex and concave dips. The zigzag pattern of normal faults (average strikes N23°W and N5°W) indicates fault formation in orthorhombic symmetry in response to N76° ± 10°E extension, orthogonal to the volcanic arc. Three oblique transfer zones divide the rift along strike into four segments with different fault trends and uplift/subsidence patterns. Differential strain across the transfer zones is accommodated by interdigitating, rift-parallel faults and some cross-rift volcanism, rather than by strike- or oblique-slip faults. From estimates of extension (2-5 km), the age of the rift (~2 Ma), and the accelerating subsidence, we infer that the Sumisu Rift is in the early syn-rift stage of backarc basin formation. Following an early sag phase, a half graben formed with a synthetically faulted, structural rollover facing large-offset border fault zones. In the three northern rift segments, the largest faults are on the arc side and dip 60°-75°W, whereas in the southern segment they are on the west side and dip 25°-50°E.
    [Show full text]
  • Styles and Scales of Structural Inheritance Throughout Continental Rifting
    Styles and Scales of Structural Inheritance throughout Continental Rifting Examples from the Great South Basin, New Zealand Thomas B. Phillips* & Ken J. McCaffrey Durham University *[email protected] Rationale Continental crust comprises distinct crustal units and intruded magmatic material brought together throughout multiple tectonic events Samsu al., (2018) et Beniest et al., (2018) • Crustal/lithospheric strength may • Strain may initially localise in weaker influence the rift structural style and areas of lithosphere, rather than at the physiography boundaries between different domains How do lateral crustal strength contrasts, along with prominent crustal boundaries, influence rift structural style and physiography? • The Great South Basin, New Zealand forms atop basement comprising multiple distinct terranes and magmatic intrusions. • The extension direction during rifting is parallel to the terrane boundaries, such that all terranes experience extensional strain Geological evolution of Zealandia A C Area of focus - 1. Cambrian- Cret. subduction along Great South Basin S. margin of Gondwana 3. Gondwana breakup Aus-NZ and NZ-West Antarctica. Formation of rift basins on cont. shelf B D 2. Ribbon-like accretion of distinct island-arc- related terranes 4. Formation of oppositely dipping subduction zones and offsetting of Uruski. (2010) basement terranes Courtesy of IODP Basement beneath the Great South Basin Work in progress/Preliminary • Distinct basement terranes of varying strength related to Island Arc system accreted
    [Show full text]
  • A New Look at Maverick Basin Basement Tectonics Michael Alexander, Integrated Geophysics Corporation
    Bulletin of the South Texas Geological Society A New Look at Maverick Basin Basement Tectonics Michael Alexander, Integrated Geophysics Corporation 50 Briar Hollow Lane, Suite 400W Houston, Texas 77027 Technical Article Technical ABSTRACT concepts regarding the evolution and relationships of the various sub-basins and regional faulting. The current Eagle Ford play in South Texas has More importantly, it could stimulate new ideas regenerated exploration interest in the Maverick about exploring for several potential new and Basin area. The greater Maverick Basin is shown deeper plays in the Jurassic and pre-Jurassic to consist of several sub-basins, each having a section. unique tectonic character. Three broad Cretaceous basins overlie narrow Jurassic basins that are considered to be part of a left-stepping rift system INTRODUCTION associated with a regional southeast-northwest shear zone. Much of the current literature considers the greater Maverick Basin to be a classic Jurassic rift valley. The northern Maverick area contains two deep and Some papers describe the northern sub-basin as a narrow Jurassic sub-basins, the Moody and the deep Jurassic rift bounded to the southwest by Paloma, both of which trend southeast-northwest. northeast-directed folds or anticlines produced by This northern area is separated from the central Laramide compression from Mexico. Other Maverick area by a southwesterly trend of papers describe the central sub-basin as a interpreted basement highs associated with the Cretaceous-Jurassic half-graben with the Chittim Edwards Arch. A Jurassic rift basin, the Chittim Anticline located over its steep northeast flank. Basin, is located in the central Maverick area.
    [Show full text]
  • Development of the Rocky Mountain Foreland Basin: Combined Structural
    University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2007 DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA Emily Geraghty Ward The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Ward, Emily Geraghty, "DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA" (2007). Graduate Student Theses, Dissertations, & Professional Papers. 1234. https://scholarworks.umt.edu/etd/1234 This Dissertation is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA By Emily M. Geraghty Ward B.A., Whitman College, Walla Walla, WA, 1999 M.S., Washington State University, Pullman, WA, 2002 Dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geology The University of Montana Missoula, MT Spring 2007 Approved by: Dr. David A. Strobel, Dean Graduate School James W. Sears, Chair Department of Geosciences Julia A. Baldwin Department of Geosciences Marc S. Hendrix Department of Geosciences Steven D.
    [Show full text]
  • Deformation Pattern During Normal Faulting: a Sequential Limit Analysis
    Originally published as: Yuan, X., Maillot, B., Leroy, Y. M. (2017): Deformation pattern during normal faulting: A sequential limit analysis. ‐ Journal of Geophysical Research, 122, 2, pp. 1496—1516. DOI: http://doi.org/10.1002/2016JB013430 Journal of Geophysical Research: Solid Earth RESEARCH ARTICLE Deformation pattern during normal faulting: 10.1002/2016JB013430 A sequential limit analysis Key Points: • New 2-D mechanically balanced X. P. Yuan1,2 , B. Maillot3, and Y. M. Leroy1,4 model of formation and evolution of half-grabens above low-angle normal 1Laboratoire de Géologie, CNRS UMR, École Normale Supérieure, Paris, France, 2Now at Helmholtz Centre Potsdam, detachment 3 • Tectonic extensional and gravitational German Research Center for Geosciences (GFZ), Potsdam, Germany, Laboratoire Géosciences et Environnement Cergy, 4 modes of deformation in frictional Université de Cergy-Pontoise, Cergy-Pontoise, France, Now at Total, CSTJF, Pau, France wedges are well captured • Fault weakening and sedimentation control number of fault-bounded Abstract We model in 2-D the formation and development of half-graben faults above a low-angle blocks in hanging wall normal detachment fault. The model, based on a “sequential limit analysis” accounting for mechanical equilibrium and energy dissipation, simulates the incremental deformation of a frictional, cohesive, and Supporting Information: fluid-saturated rock wedge above the detachment. Two modes of deformation, gravitational collapse and • Supporting Information S1 tectonic collapse, are revealed which compare well with the results of the critical Coulomb wedge theory. •MovieS1 •MovieS2 We additionally show that the fault and the axial surface of the half-graben rotate as topographic •MovieS3 subsidence increases. This progressive rotation makes some of the footwall material being sheared and •MovieS4 entering into the hanging wall, creating a specific region called foot-to-hanging wall (FHW).
    [Show full text]
  • Pamphlet to Accompany
    Geologic and Geophysical Maps of the Eastern Three- Fourths of the Cambria 30´ x 60´ Quadrangle, Central California Coast Ranges Pamphlet to accompany Scientific Investigations Map 3287 2014 U.S. Department of the Interior U.S. Geological Survey This page is intentionally left blank Contents Contents ........................................................................................................................................................................... ii Introduction ..................................................................................................................................................................... 1 Interactive PDF ............................................................................................................................................................ 2 Stratigraphy ..................................................................................................................................................................... 5 Basement Complexes ................................................................................................................................................. 5 Salinian Complex ..................................................................................................................................................... 5 Great Valley Complex ............................................................................................................................................ 10 Franciscan Complex .............................................................................................................................................
    [Show full text]
  • Lithospheric Folding and Sedimentary Basin Evolution: a Review and Analysis of Formation Mechanisms Sierd Cloething, Evgenii Burov
    Lithospheric folding and sedimentary basin evolution: a review and analysis of formation mechanisms Sierd Cloething, Evgenii Burov To cite this version: Sierd Cloething, Evgenii Burov. Lithospheric folding and sedimentary basin evolution: a review and analysis of formation mechanisms. Basin Research, Wiley, 2011, 23 (3), pp.257-290. 10.1111/j.1365- 2117.2010.00490.x. hal-00640964 HAL Id: hal-00640964 https://hal.archives-ouvertes.fr/hal-00640964 Submitted on 24 Nov 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Basin Research For Review Only Page 1 of 91 Basin Research 1 2 3 4 1 Lithospheric folding and sedimentary basin evolution: 5 6 2 a review and analysis of formation mechanisms 7 8 9 3 10 11 4 12 13 5 14 a,* b 15 6 Sierd Cloetingh and Evgenii Burov 16 7 17 18 8 aNetherlands ResearchFor Centre forReview Integrated Solid EarthOnly Sciences, Faculty of Earth and Life 19 20 9 Sciences, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. 21 10 22 23 11 bUniversité Pierre et Marie Curie, Laboratoire de Tectonique, 4 Place Jussieu, 24 25 12 75252 Paris Cedex 05, France.
    [Show full text]
  • Constraining the Tectonic Evolution of Extensional Fault Systems in the Cyclades (Greece) Using Low-Temperature Thermochronology Stephanie Brichau
    Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology Stephanie Brichau To cite this version: Stephanie Brichau. Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology. Applied geology. Université Montpellier II - Sciences et Techniques du Languedoc; Johannes Gutenberg Universität Mainz, 2004. English. tel- 00006814 HAL Id: tel-00006814 https://tel.archives-ouvertes.fr/tel-00006814 Submitted on 3 Sep 2004 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Universität Mainz “Johannes Gutenberg” and Université de Montpellier II “Sciences et techniques du Languedoc” Dissertation zur Erlangung des Grades “DOKTOR DER NATURWISSENSCHAFTEN” am Fachbereich Geowissenschaften der Johannes Gutenberg-Universität Mainz THESE Pour obtenir le grade de “DOCTEUR DE L’UNIVERSITÉ MONTPELLIER II” Discipline: Terre solide, géodynamique Formation Doctorale: Structure et Evolution de la Lithosphère Ecole Doctorale: Science de la Terre et de l’Eau Presented and publicly defended at Mainz by Stéphanie Brichau June 29th, 2004 Title: Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology JURY M. Stephen Foley GP, Mainz President M. Michel Faure IST, Orléans Reviewer M.
    [Show full text]
  • "Extension Layer-Parallel Shear and Normal Faulting."
    * * A/H6 Extensional layer-parallel shear and normal faulting DAVID A. FERRILL Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 ALAN P. MORRIS Division of Earth and Physical Sciences, University of Texas at San Antonio, San Antonio, Texas 78249 SIDNEY M. JONES and JOHN A. STAMATAKOS Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 Abstract-An extensional fault system in Bare Mountain, Nevada, contains abundant evidence of layer-parallel shear deformation contemporaneous with faulting. Layer-parallel shear is manifest by deformation of pre-existing fabrics such as teeth on bedding-parallel stylolites and shape fabrics in fossiliferous and oolitic limestone that all indicate shear in the down-dip direction, perpendicular to fault-bedding intersections. Cleavage at a low angle to bedding has the same vergence, indicating development and/or modification during shear parallel to bedding with a down-dip sense. Localized layer-parallel shear along discrete bedding planes has locally offset normal faults, and shear distributed within layers has reoriented block-bounding normal faults. These observations of internal deformation within fault blocks indicate that layer-parallel shear contributes to fault block deformation. In simple rigid-block models of extension accommodated by normal faults above a low-angle detachment or decollement zone, extension causes faults to rotate to progressively lower dips, while originally horizontal beds rotate to steeper dips. These rotations reorient faults away from originally optimum conditions for slip 2 into orientations of a lower slip tendency, whereas bedding rotates to steeper dips with progressively higher slip tendency.
    [Show full text]
  • The Shumagin Seismic Gap Structure and Associated Tsunami Hazards, Alaska Convergent Margin GEOSPHERE, V
    Research Paper THEMED ISSUE: Subduction Top to Bottom 2 GEOSPHERE The Shumagin seismic gap structure and associated tsunami hazards, Alaska convergent margin GEOSPHERE, v. 15, no. 2 Roland von Huene1,*,†, John J. Miller2,*,†, and Anne Krabbenhoeft3 https://doi.org/10.1130/GES01657.1 1U.S. Geological Survey, 800 Blossom Hill Road, Los Gatos, California 95032, USA 2U.S. Geological Survey, Denver Federal Center, Denver, Colorado 80225, USA 3 14 figures; 1 set of supplemental files GEOMAR Helmholz Centre for Ocean Research, D-24148, Kiel, Germany CORRESPONDENCE: rhuene@ mindspring .com ABSTRACT ruptured in the 1964 great earthquake, the Semidi segment that broke in a CITATION: von Huene, R., Miller, J.J., and Krabben‑ 1938 earthquake, and the Unimak segment that ruptured in 1946. In contrast, hoeft, A., 2019, The Shumagin seismic gap structure and associated tsunami hazards, Alaska convergent The potential for a major earthquake in the Shumagin seismic gap, and the the Shumagin segment has no historic great earthquake and is constrained by margin: Geosphere, v. 15, no. 2, p. 324–341, https:// tsunami it could generate, was reported in 1971. However, while potentially its neighboring segments rather than its own aftershocks. Since Sykes (1971) doi .org /10 .1130 /GES01657.1. tsunamigenic splay faults in the adjacent Unimak and Semidi earthquake seg- first drew attention to the Shumagin segment, it has been a proposed seismic ments are known, such features along the Shumagin segment were undoc- gap. Earthquakes in the adjacent segments have produced tsunamis. To the Science Editor: Shanaka de Silva umented until recently. To investigate margin structure and search for splay southwest, during the 1946 M8.6 earthquake, the Unimak segment generated Associate Editor: Laura M.
    [Show full text]