DOCSLIB.ORG

Upward Shallowing Platform Cycles a Response to 2.2 Billion Years of Lowamplitude, Highfrequency Milankovitch Band Sea Level

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Upward Shallowing Platform Cycles a Response to 2.2 Billion Years of Lowamplitude, Highfrequency Milankovitch Band Sea Level PALEOCEANOGRAPHY,VOL. 1, NO. 4, PAGES 403-416, DECEMBER 1986 UPWARD SHALLOWING PLATFORM CYCLES: A RESPONSE TO 2.2 BILLION YEARS OF LOW-AMPLITUDE, HIGH-FREQUENCY (MILANKOVITCH BAND) SEA LEVEL OSCILLATIONS J. P. Grotzinger Lamont-Doherty Geological Observatory, Palisades, New York Abstract. Shallow-water carbonate perhaps influencing global sea level platforms, characterized by sequences of through minor changes related to small- small-scale upward shallowing cycles, are scale continental or alpine glaciation. common in the Phanerozoic and Proterozoic It is possible, then, that Milankovitch stratigraphic record. Proterozoic small- band climatic forcing has occurred for at scale cycles are commonly 1 to 10 m thick, least the last 2.2 billion years of earth have asymmetrically arranged facies, and history. are strikingly similar to Phanerozoic platform cycles. In some platform INTRODUCTION sequences (eg. Rocknest, Wallace, and Helena formations of early to middle The stratigraphic record of geologic Proterozoic age), it can be demonstrated history is characterized by intervals of that the lateral distribution of facies pronounced rhythmic or cyclic arrangement within cycles relates to systematic of facies such that repetitive groups of variations in platform paleogeography and rock units have component facies which topography. In the Rocknest formation, tend to occur in certain order. cycles with intervals of tepees and Sedimentary cyclicity has been documented pisolitic breccia formed on a topographic in many paleoenvironmental settings high (shoal complex) near the shelf edge ranging from fluvial to deep sea, in both rim, and provide evidence for eustatic carbonate- and siliciclastic-dominated falls in sea level at the end of each systems [e.g. Beerbower, 1964; Hays et cycle. The presence of these facies in al., 1976; Olsen, 1984; Arthur et al., other Proterozoic cyclic platforms also 1984; James, 1984; Goodwin and Anderson, suggests that eustatic sea level falls may 1985]. Both autogenic and allogenic have been important in the development of models have been proposed to account for each cycle. Proterozoic upward shallowing this cyclicity, but in recent years new cycles appear to have had periods of evidence has been collected that is between 20,000 and 100,000 years, and compatible with a Milankovitch-forced probably formed during eustatic control over many cyclic systems. oscillations in sea level with amplitudes The effect of Milankovitch band forcing of less than 10 m. This suggests that on cyclicity of Pleistocene deep sea cyclicity may have been regulated by sediments is almost irrefutable [Hays et Milankovitch band climatic forcing, al., 1976], and Milankovitch band forcing is probably the cause of cyclicity in Copyright 1986 earlier Cenozoic [Mathews and Poore, by the American Geophysical Union. 1980], Cretaceous [Arthur et al., 1984], and Jurassic deep water sequences. The Paper number 6P0531. recognition of Milankovitch band climatic 0883-8305/86/006P-0531510.00 forcing in Cenozoic and Mezozoic deep 404 Grotzinger: Upward Shallowing Platform Cycles problems arise primarily from poor exposures of many cyclic platforms, which prohibits detailed studies of individual cycles on a lateral basis, in turn leading to a poor understanding of cycle dynamics and determinant mechanisms. This paper provides new insights into the general question of cyclicity of shallow-water platforms in geologic history by (1) discussing the paleogeography and cycle dynamics of a superbly exposed early Proterozoic cyclic platform and its significance in understanding general mechanisms of cyclicity, (2) discussing general models for the development of platform cycles, independent of age, and (3) reviewing the occurrence and possible causes of other cyclic sequences in the Proterozoic record, thereby establishing that cyclic platform sedimentation, and perhaps Milankovitch band forcing, has been J ROCKNEST FORMATION important for at least the last 2.2 billion years of earth history. Fig. 1. Location of Rocknest formation, Wopmay orogen, northwest Canadian Shield. MECHANISMS OF CYCLICITY, ROCKNEST PLATFORM marine sediments has been successful The early Proterozoic (1.9 Ga) Rocknest primarily becase of three factors: (1) formation is exposed in Wopmay orogen, other extrinsic controls such as episodic northwest Canada (Figure 1). It is part subsidence have a minimal effect on of a continental margin sedimentary prism stratigraphic accumulation in the deep-sea composed of a basal rift sequence, a environment, (2) the deep-sea record tends middle passive-margin sequence, and to be more complete than that of platform overlying foredeep sequence [Hoffman, sediments, and (3) biostratigraphic and 1980; Hoffman and Bowring, 1984]. The magnetostratigraphic zonation are upper part of the passive-margin sequence excellent for the Cenozoic and Mesozoic. (Rocknest formation) is a cyclic, dolomite In fact, the evidence is so overwhelming shelf sequence with a stromatolitic reefal for a Milankovitch-forced climatic control rim and flanking debris apron [Grotzinger, over Cenozoic and Mezozoic deep marine 1985, 1986a, b]. cyclicity that it has been suggested to The palinspastically restored shelf adopt the use of sedimentary cycles in sequence (Figure 2) is an eastward determining the true length of thinning prism, up to 1 km thick, chronostratigraphical zones as a new extending for over 220 km parallel to approach towards establishing an absolute depositional strike and over 200 km time scale [House, 1985]. perpendicular to strike [Grotzinger, 1985, The mechanisms responsible for 1986a, b) . The shelf sequence can be cyclicity in shallow-water marine platform divided from west to east into slope, sediments are less certain [Weller, 1964; outer shelf, shoal complex, and inner Wilkinson, 1982; James, 1984]. Although a shelf facies (Figure 3). Slope, outer Milankovitch band forcing effect has long shelf and shoal complex facies assemblages been suspected [Gilbert, 1895; Weller, are restricted to the western margin of 1930; Fischer, 1964], new evidence is the shelf; inner shelf facies occur over being gathered which supports this model most of the shelf region except adjacent [Goodwin and Anderson, 1985; Grotzinger, to its margin. Slope and outer shelf 1985, 1986b; Read et al., 1986; Heckel, facies are discussed in detail by 1986]. However, general acceptance of the Grotzinger [1985, 1986a], and are not Milankovitch model for shallow-water reviewed further here. Shoal complex and sediments has been slow because of a lack inner shelf facies are briefly reviewed of understanding of the local mechanisms here as they pertain to shelf cyclicity, which govern platform cyclicity, and how, and more detailed discussions of these if important, a Milankovitch control would facies can be found in reports by regulate platform cyclicity. These Grotzinger [1985, 1986b]. Grotzinger' Upward Shallowing Platform Cycles 405 W ROCKNEST SHELF - NORTH ß ß ß vv ß ß ß ß MNI*. %%* • IOkm r'• TUFA-BASEDCYCLES DOLOSlLTITE-BASED CYCLE .'[-•OUTER-SHELF SHALE-BASEDCYCLES SLOPE SHALE ß MEASURED SECTION TIME W ROCKNEST SHELF - SOUTH E VVVV W ß ß ß ß ß UNI•- I lOOm IO km UNI UPPER NON-CYCLIC INTERVAL "GRANDCYCLE" MNI MIDDLE LNI LOWER " Fig. 2. Palinspastic cross sections of Rocknest shelf stratigraphy. Note well developed W-E facies zonation including slope, outer shelf (rim boundstone and backreef grainstone), shoal complex (tufa-based cycles), proximal inner shelf (dolosiltite-based cycles), distal inner shelf (shale- based cycles), and lagoon (shale) . Shoal Complex_ During the course of cycle development at the shoal complex, deposition of Lithofacies. Shoal complex facies laminated dolosiltite and lutite, occur in a narrow belt, 1 to 5 km wide cryptalgalaminite, and tufa was followed (Figures 2 and 3). Sediments are arranged by lowering of the water table and cyclically, so that cryptalgalaminite, establishment of a vadose zone which tufa, and laminated dolosiltite and lutite favored tepee,breccia and pisolite are overlain by disrupted equivalents, formation. These facies are critical in developed as tepees and breccias with deriving the mechanism responsible for associated pisolite (Figure 4). cyclicity, suggesting strongly that 406 Grotzinger: UpwardShallowing Platform Cycles w ROCKNEST SHELF 5-10 km = I •- 100-200 km - I LAGOONAL FAIRWEATHER SHOAL COMPLEX .•, o MUDS (• o WAVE BASE o SANDS STORM o W. CYCLIC TIDAL FLATS BACK REEF SANDS SHELF EDGE LOWERSLOPE • REEFS UPPER SLOPE RHYTHMITES,..• RHYTHMITES,EDGE.CGL.,8• TURBIDITES,8• DOWNSLOPEBIOHERMS BRECCIAS Fig. 3. Rocknest shelf paleogeography. Cyclic deposits formed by limited westward and extensive eastward progradation of shoal complex in response to low-amplitude, high-frequency sea level oscillations (see text). eustatic sea level falls were important in kilometers) and pass westward into shoal establishing a vadose zone at the top of complex facies and eastward into lagoonal each cycle. siliciclastic shale, siltstone, and Interpretation. Cyclical sequences in sandstone. Generally, inner shelf facies the shoal complex are interpreted to occur in asymmetric, upward shallowing reflect low-amplitude, high-frequency cycles which can be classified according oscillations in sea level [Grotzinger, to cycle base lithology, reflecting 1985, 1986b]. Initially, upper intertidal paleogeographic position on the shelf to supratidal sedimentation occurred (Figure 4). Shale-based cycles have the during small rises in sea level and most diverse facies
Load more

Recommended publications
  • Deciphering the Origin of Cyclical Gravel Front and Shoreline Progradation and Retrogradation in the Stratigraphic Record
    Deciphering the origin of cyclical gravel front and shoreline progradation and retrogradation in the stratigraphic record John J. Armitage1, Peter A. Burgess2, Gary J. Hampson3, and Philip A. Allen3 1Department of Earth Science, Royal Holloway, University of London, Egham, UK; Now at Institut de Physique du Globe de Paris, 1 rue Jussieu, Paris, 75005, France; e-mail: [email protected] 2Department of Earth Science, Royal Holloway, University of London, Egham, UK 3Department of Earth Science and Engineering, Imperial College London, London, UK May 4, 2016 1 1 Abstract 2 Nearly all successions of near-shore strata exhibit cyclical movements of the shoreline, which 3 have commonly been attributed to cyclical oscillations in relative sea level (combining eustasy 4 and subsidence) or, more rarely, to cyclical variations in sediment supply. It has become accepted 5 that cyclical change in sediment delivery from source catchments may lead to cyclical movement 6 of boundaries such as the gravel front, particularly in the proximal segments of sediment routing 7 systems. In order to quantitatively assess how variations in sediment transport as a consequence 8 of change in relative sea-level and surface run-off control stratigraphic architecture, we develop a 9 simple numerical model of sediment transport and explore the sensitivity of moving boundaries 10 within the sediment routing system to change in upstream (sediment flux, precipitation rate) and 11 downstream (sea level) controls. We find that downstream controls impact the shoreline and sand 12 front, while the upstream controls can impact the whole system depending on the amplitude of 13 change in sediment flux and precipitation rate.
    [Show full text]
  • A Geoarchaeological Perspective on the Challenges and Trajectories of Mississippi Delta Communities
    Geomorphology 360 (2020) 107132 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph A geoarchaeological perspective on the challenges and trajectories of Mississippi Delta communities Elizabeth L. Chamberlain a,b,c,⁎, Jayur M. Mehta d, Tony Reimann c,JakobWallingac a Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN, USA b Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA c Netherlands Centre for Luminescence Dating, Soil Geography and Landscape group, Wageningen University, Wageningen, the Netherlands d Department of Anthropology, Florida State University, Tallahassee, FL, USA article info abstract Article history: Recent geochronology of the Mississippi Delta of coastal Louisiana, USA, provides a high-resolution record of land Received 31 October 2019 growth that facilitates the study of ancient settlement patterns in relation to delta evolution. We use stratigraphy Received in revised form 27 February 2020 and optically stimulated luminescence (OSL) dating to show that two Late Holocene earthen mounds were con- Accepted 27 February 2020 structed several hundred years after the land emerged from open water. This multi-century pause allowed nat- Available online 2 March 2020 ural processes of overbank and crevasse splay deposition to elevate the land surface, reduce flood risk, and foster desirable environmental conditions prior to human occupation. These results are applied to obtain new age con- Keywords: Coupled human-natural systems straints for a large number of at-risk or lost archaeological sites with little-to-no absolute chronology. We use our Mississippi Delta findings to comment on prehistoric, contemporary, and future human-landscape interactions in the Mississippi Optically stimulated luminescence dating Delta and other deltaic environments.
    [Show full text]
  • Article Is Available Engineers, Available At: Online At
    Earth Surf. Dynam., 6, 1155–1168, 2018 https://doi.org/10.5194/esurf-6-1155-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Measuring subaqueous progradation of the Wax Lake Delta with a model of flow direction divergence John B. Shaw1, Justin D. Estep1,2, Amanda R. Whaling1, Kelly M. Sanks1, and Douglas A. Edmonds3 1Department of Geosciences, University of Arkansas, Fayetteville, 72701, USA 2Department of Geology and Geophysics, Texas A&M University, College Station, 77843, USA 3Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, 47405, USA Correspondence: John B. Shaw ([email protected]) Received: 1 June 2018 – Discussion started: 22 June 2018 Revised: 8 November 2018 – Accepted: 19 November 2018 – Published: 30 November 2018 Abstract. Remotely sensed flow patterns can reveal the location of the subaqueous distal tip of a distributary channel on a prograding river delta. Morphodynamic feedbacks produce distributary channels that become shal- lower over their final reaches before the unchannelized foreset slopes basinward. The flow direction field over this morphology tends to diverge and then converge, providing a diagnostic signature that can be captured in flow or remote sensing data. A total of 21 measurements from the Wax Lake Delta (WLD) in coastal Louisiana and 317 measurements from numerically simulated deltas show that the transition from divergence to convergence occurs in a distribution that is centered just downstream of the channel tip, on average 132 m in the case of the WLD. These data validate an inverse model for remotely estimating subaqueous channel tip location. We apply this model to 33 images of the WLD between its initiation in 1974 and 2016.
    [Show full text]
  • Carbonate Platform Evolution: from a Bioconstructed Platform Margin to a Sand-Shoal System (Devonian, Guilin, South China)
    Sedimentology (2002) 49, 737–764 Carbonate platform evolution: from a bioconstructed platform margin to a sand-shoal system (Devonian, Guilin, South China) DAIZHAO CHEN*, MAURICE E. TUCKER , JINGQUAN ZHU* and MAOSHENG JIANG* *Institute of Geology and Geophysics, Chinese Academy of Sciences, PO Box 9825, Beijing 100029, China (E-mail: [email protected]) Department of Geological Sciences, University of Durham, Durham DH1 3LE, UK (E-mail: [email protected]) ABSTRACT The depositional organization and architecture of the middle–late Devonian Yangdi rimmed carbonate platform margin in the Guilin area of South China were related to oblique, extensional faulting in a strike-slip setting. The platform margin shows two main stages of construction in the late Givetian to Frasnian, with a bioconstructed margin evolving into a sand-shoal system. In the late Givetian, the platform margin was rimmed with microbial buildups composed mainly of cyanobacterial colonies (mostly Renalcis and Epiphyton). These grew upwards and produced an aggradational (locally slightly retrogradational) architecture with steep foreslope clinoforms. Three depositional sequences (S3–S5) are recognized in the upper Givetian strata, which are dominated by extensive microbialites. Metre-scale depositional cyclicity occurs in most facies associations, except in the platform-margin buildups and upper foreslope facies. In the latest Givetian (at the top of sequence S5), relative platform uplift (± subaerial exposure) and associated rapid basin subsidence (probably a block-tilting effect) caused large-scale platform collapse and slope erosion to give local scalloped embayments along the platform margin and the synchronous demise of microbial buildups. Subsequently, sand shoals and banks composed of ooids and peloids and, a little later, stromatoporoid buildups on the palaeohighs, developed along the platform margin, from which abundant loose sediment was transported downslope to form gravity-flow deposits.
    [Show full text]
  • Facies Analysis, Genetic Sequences, and Paleogeography of the Lower Part of the Minturn Formation (Middle Pennsylvanian), Southeastern Eagle Basin, Colorado
    Facies Analysis, Genetic Sequences, and Paleogeography of the Lower Part of the Minturn Formation (Middle Pennsylvanian), Southeastern Eagle Basin, Colorado U.S. GEOLOGICAL SURVEY BULLETIN 1 787-AA ^A2 Chapter AA Facies Analysis, Genetic Sequences, and Paleogeography of the Lower Part of the Minturn Formation (Middle Pennsylvanian), Southeastern Eagle Basin, Colorado By JOHN A. KARACHEWSKI A multidisciplinary approach to research studies of sedimentary rocks and their constituents and the evolution of sedimentary basins, both ancient and modern U.S. GEOLOGICAL SURVEY BULLETIN 1 787 EVOLUTION OF SEDIMENTARY BASINS UINTA AND PICEANCE BASINS U.S. DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government UNITED STATES GOVERNMENT PRINTING OFFICE: 1992 For sale by the Books and Open-File Report Sales U.S. Geological Survey Federal Center Box 25425 Denver, CO 80225 Library of Congress Cataloging-in-Publication Data Karachewski, John A. Facies analysis, genetic sequences, and paleogeography of the lower part of the Minturn Formation (Middle Pennsylvanian), Southeastern Eagle Basin, Colorado/ by John A. Karachewski. p. cm. (U.S. Geological Survey bulletin ; 1787) Evolution of sedimentary basins Uinta and Piceance basins ; ch. AA) Includes bibliographical references. Supt. of Docs, no.: I 19.3:1787 1. Sedimentation and deposition Colorado Eagle County. 2. Geology, Stratigraphic Pennsylvanian. 3. Geology, Stratigraphic Paleozoic. 4. Geology, Stratigraphic Colorado Eagle County. 5. Paleogeography Paleozoic. 6. Minturn Formation sedimentary basins Uinta and Piceance basins ; ch.
    [Show full text]
  • Tracking the Fate of Sediment After an Extreme Flood
    Hydrology Days 2018 Tracking the Fate of Sediment After an Extreme Flood Johanna S. Eidmann1, Sara L. Rathburn1, Ken Huson2 1Department of Geology, Colorado State University 2City of Longmont, CO Abstract. Assessing the ongoing sediment remobilization and deposition following an extreme flood is important for understanding disturbance response and recovery, and for addressing the challenges to water resource management. From September 9-15, 2013, a tropical storm generated over 350 mm of precipitation across the Colorado Front Range. The resulting 200-year flood triggering landslides and extreme channel erosion along North St. Vrain Creek that feeds Ralph Price Reservoir, an important water supply for the Cities of Lyons and Longmont, CO. The flood resulted in 10 m of aggradation upstream of the reservoir, transforming the inlet into an approach channel. Four years after the flood, downstream transport of flood sediment and deposition in the reservoir continues. This research tracks the fate of flood-derived sediment to understand the evolution and progradation of the delta as well as to inform reservoir management practices. Bathymetric DEM differencing from April 2014, April 2016, May 2017 and August 2017 (years 1, 2, 3 and 4 post-flood, respectively) demonstrates a constant rate of delta progradation of ~50 m per year since 2014. Between April 2016 and May 2017, the reservoir level was dropped approximately 10 m during reconstruction at the spillway. Despite the change in base level, year 4 pre-snowmelt runoff measurements indicate that the rate of progradation has remained comparable to the two years following the flood. Assuming that most sediment is transported during snowmelt runoff, year 4 post-snowmelt runoff bathymetry suggests a decline in progradation rate.
    [Show full text]
  • Framework and Evolution of a Transgressed Delta Lobe: the St
    University of New Orleans ScholarWorks@UNO University of New Orleans Theses and Dissertations Dissertations and Theses 5-15-2009 Framework and Evolution of a Transgressed Delta Lobe: The St. Bernard Shoals, Gulf of Mexico Bryan E. Rogers University of New Orleans Follow this and additional works at: https://scholarworks.uno.edu/td Recommended Citation Rogers, Bryan E., "Framework and Evolution of a Transgressed Delta Lobe: The St. Bernard Shoals, Gulf of Mexico" (2009). University of New Orleans Theses and Dissertations. 968. https://scholarworks.uno.edu/td/968 This Thesis is protected by copyright and/or related rights. It has been brought to you by ScholarWorks@UNO with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights- holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Thesis has been accepted for inclusion in University of New Orleans Theses and Dissertations by an authorized administrator of ScholarWorks@UNO. For more information, please contact [email protected]. Framework and Evolution of a Transgressed Delta Lobe: The St. Bernard Shoals, Gulf of Mexico A Thesis Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirements for the degree of Master of Science in Earth and Environmental Sciences Coastal Geology by Bryan E. Rogers B.S. University of New Orleans, 2006 May 2009 Dedication I dedicate this master’s thesis to the late Dr.
    [Show full text]
  • Geomorphology, Hydrology, and Ecology of Great Basin Meadow
    Chapter 2: Controls on Meadow Distribution and Characteristics Dru Germanoski, Jerry R. Miller, and Mark L. Lord Introduction precipitation values are recorded in the central and southern Toiyabe and southern Toquima Mountains (fig. 1.4) and, as eadow complexes are located in distinct geomorphic expected, meadow complexes are abundant in those areas. Mand hydrologic settings that allow groundwater to be In contrast, basins located in sections of mountain ranges at or near the ground surface during at least part of the year. that do not have significant area at high elevation (greater Meadows are manifestations of the subsurface flow system, than approximately 2500 m) and that are characterized by and their distribution is controlled by factors that cause lo- limited annual precipitation contain relatively few meadows. calized zones of groundwater discharge. Knowledge of the For example, much of the Shoshone Range and the north- factors that serve as controls on groundwater discharge and ern and southernmost portions of the Toiyabe, Toquima, and formation of meadow complexes is necessary to understand Monitor Ranges are lower in elevation and receive less pre- why meadows occur where they do and how anthropogenic cipitation. Therefore, meadow complexes are uncommon in activities might affect their persistence and ecological condi- these regions. Analyses of color-enhanced satellite images tion. In this chapter, we examine physical factors that lead to of the region reveal that meadow complexes also are uncom- the formation of meadow complexes in upland watersheds mon in low-elevation mountain ranges in the surrounding of the central Great Basin. We then describe variations in area, including the Pancake Range, Antelope Range, the meadow characteristics across the region and parameters Park Range, and Simpson Park Mountains.
    [Show full text]
  • Dynamic Fluvial Systems and Gravel Progradation in the Himalayan Foreland
    Dynamic fluvial systems and gravel progradation in the Himalayan foreland Nicholas Brozovic´* Department of Earth Sciences, University of Southern California, Los Angeles, California 90089 Douglas W. Burbank†} ABSTRACT Keywords: fold-and-thrust belt, basin analysis, posits are generally marked by a paucity of fossil Siwaliks, Himalaya, magnetostratigraphy. material of known age, making biostratigraphy Although the large-scale stratigraphy of difficult. In such areas without fossils or radio- many terrestrial foreland basins is punctu- INTRODUCTION metrically dateable volcanic rocks, magnetostra- ated by major episodes of gravel prograda- tigraphy can sometimes provide excellent temporal tion, the relationships of such facies to hinter- The evolution of terrestrial foreland basins is control if sufficiently long, continuous strati- land tectonism and climate change are often marked by the reorganization of fluvial systems on graphic sections can be studied (Burbank, 1996). unclear. Structural reentrants provide win- spatial scales of kilometers to thousands of kilo- dows into older and more proximal parts of meters at temporal scales ranging from coseismic GEOLOGIC FRAMEWORK OF THE the foreland than are usually exposed, and to millennia (e.g., Meghraoui et al., 1988; Bur- HIMALAYAN FORELAND thus provide key insights to earlier phases of bank, 1992; Talling et al., 1995; Pivnik and John- foreland evolution. Our magnetostrati- son, 1995). Depositional systems within the fore- India-Asia collision was initiated as early as graphic studies show that, although the ma- land respond to changes in at least five factors: (1) 65 Ma in the westernmost part of the orogen jor lithofacies preserved within the Himachal flexure of the loaded plate, (2) incipient deforma- (Beck et al., 1995).
    [Show full text]
  • Modeling Coastal River, Wetland, and Shoreline Dynamics
    From the River to the Sea: Modeling Coastal River, Wetland, and Shoreline Dynamics by Katherine Murray Ratliff Earth & Ocean Sciences Duke University Date: Approved: A. Brad Murray, Supervisor Marco Marani Peter Haff James Heffernan Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Earth & Ocean Sciences in the Graduate School of Duke University 2017 Abstract From the River to the Sea: Modeling Coastal River, Wetland, and Shoreline Dynamics by Katherine Murray Ratliff Earth & Ocean Sciences Duke University Date: Approved: A. Brad Murray, Supervisor Marco Marani Peter Haff James Heffernan An abstract of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Earth & Ocean Sciences in the Graduate School of Duke University 2017 Copyright c 2017 by Katherine Murray Ratliff All rights reserved except the rights granted by the Creative Commons Attribution-Noncommercial Licence Abstract Complex feedbacks dominate landscape dynamics over large spatial scales (10s { 100s km) and over the long-term (10s { 100s yrs). These interactions and feedbacks are particularly strong at land-water boundaries, such as coastlines, marshes, and rivers. Water, although necessary for life and agriculture, threatens humans and infrastructure during natural disasters (e.g., floods, hurricanes) and through sea-level rise. The goal of this dissertation is to better understand landscape morphodynamics in these settings, and in some cases, to investigate how humans have influenced these landscapes (e.g., through climate or land-use change). In this work, I use innovative numerical models to study the larger-scale emergent interactions and most critical variables of these systems, allowing me to clarify the most important feedbacks and explore large space and time scales.
    [Show full text]
  • Sea-Level Change and Delta Growth, Fraser Delta, British Columbia
    SEA-LEVEL CHANGE AND DELTA GROWTH: FRASER DELTA, BRITISH COLUMBIA Harry F. L. Williams B.Sc (HONS) Plymouth Polytechnic 1980 M.Sc University of ~ritishColumbia 1983 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Geography Harry F. L. Williams 1988 SIMON FRASER UNIVERSITY July 1988 All rights reserved. This work may not be reproduced in whole, or in part, by photocopy or other means, without permission of the author. APPROVAL Name : Harry F. L. ~illiams Degree: Ph. D Geography Title of thesis: Sea-Level Change And Delta Growth: Fraser Delta, British Columbia Examining Committee: Chairman: Dr. L. Evenden Dr. M. C. Roberts Senior Supervisor- Dr. -E. J. Hickin Dr. P~utchinson AD/[ J. L. ~uteinauer Geological Survey of Canada - -. J. D'Auria artment of Chemistjy 1,- - - y,,, D'- D'- External Examiner Department of Geography University of Calgary Date Approved: @/ PARTIAL COPYRIGHT LICENSE I hereby grant to Slmn Fraser University the right to lend my thesis, project or extended essay (the title of which is shown below) to users ot the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this work for scholarly purposes may be granted by me or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without my written permission.
    [Show full text]
  • Survival of a Submarine Canyon During Long-Term Outbuilding of a Continental Margin
    G 33178 2nd pages Survival of a submarine canyon during long-term outbuilding of a continental margin David Amblas1, T.P. Gerber2, B. De Mol3, R. Urgeles4, D. Garcia-Castellanos5, M. Canals1, L.F. Pratson6, N. Robb7, and Jason Canning7 1GRC Geociències Marines, Departament d’Estratigrafi a, Paleontologia i Geociències Marines, Universitat de Barcelona, E-08028 Barcelona, Catalonia, Spain 2Department of Geoscience, Indiana University of Pennsylvania, Pennsylvania 15705, USA 3GRC Geociències Marines, Parc Científi c de Barcelona, Universitat de Barcelona, E-08028 Barcelona, Catalonia, Spain 4Departament de Geologia Marina, Institut de Ciències del Mar, CSIC, E-08003 Barcelona, Catalonia, Spain 5Group of Dynamics of the Lithosphere, Institut de Ciències de la Terra ‘Jaume Almera’, CSIC, E-08028 Barcelona, Catalonia, Spain 6Division of Earth and Ocean Sciences, Duke University, Durham, North Carolina 27708, USA 7BG Group, Thames Valley Park, Reading RG6 1PT, UK ABSTRACT mic data set from the Ebro margin (EM) in the northwest Mediterranean Net-depositional submarine canyons are common in continental Sea. We identify and map a preserved middle Pleistocene paleosurface slope strata, but how they survive and prograde on constructional representing one of the initial phases of the Ebro turbidite system. We then margins is poorly understood. In this study we present fi eld evidence compare the morphology of a modern EM canyon to its ancestor mor- for the coevolution of a submarine canyon and the adjacent continen- phology defi ned on the paleosurface. We discuss the canyon’s evolution tal slope. Using a three-dimensional seismic data cube that images in light of what is known about the middle to late Pleistocene conditions the Ebro margin (northwest Mediterranean), we identify a preserved along the margin.
    [Show full text]