DOCSLIB.ORG

2. Late Quaternary Paleomagnetic Secular Variation and Chronostratigraphy from Odp Sites 1233 and 12341

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
2. Late Quaternary Paleomagnetic Secular Variation and Chronostratigraphy from Odp Sites 1233 and 12341 Tiedemann, R., Mix, A.C., Richter, C., and Ruddiman, W.F. (Eds.) Proceedings of the Ocean Drilling Program, Scientific Results Volume 202 2. LATE QUATERNARY PALEOMAGNETIC SECULAR VARIATION AND CHRONOSTRATIGRAPHY FROM ODP SITES 1233 AND 12341 Steve P. Lund,2 Joseph Stoner,3 and Frank Lamy4 ABSTRACT During Ocean Drilling Program Leg 202, detailed shipboard paleo- magnetic measurements at Sites 1233 and 1234 identified a reproduc- ible high-resolution record of paleomagnetic secular variation (PSV) at each site. These records also contained evidence for three magnetic 1Lund, S.P., Stoner, J., and Lamy, F., field excursions. This paper summarizes the complete paleomagnetic 2006. Late Quarternary paleomagnetic record from Site 1233 and the paleomagnetic record for the uppermost secular variation and chronostratigraphy from ODP Sites 30 meters from Site 1234. We also establish a detailed PSV correlation 1233 and 1234. In Tiedemann, R., between the two sites, located ~500 km apart. Twenty-seven accelerator Mix, A.C., Richter, C., and Ruddiman, mass spectrometry radiocarbon dates permit us to develop time-depth W.F. (Eds.), Proc. ODP, Sci. Results, 202: plots and detailed PSV time series for the last ~50,000 yr at both sites. College Station, TX (Ocean Drilling Based on our chronostratigraphy, the most recent excursions occur at Program), 1–22. doi:10.2973/ α odp.proc.sr.202.208.2006 ~35,000 cal. yr before present (BP) (Excursion 3 ) and ~41,000 cal. yr BP 2Department of Earth Sciences, (Excursion 3β). The excursions were named for the oxygen isotope University of Southern California, Los stages within which they occur. These two excursions are not signifi- Angeles CA 90089-0740, USA. cantly different in age from the Mono Lake Excursion and Laschamp [email protected] 3 Excursion. A third, older excursion, which has not yet been adequately School of Oceanic and Atmospheric Sciences, Oregon State University, dated, also occurs at Site 1233. Corvallis OR 97331-5503, USA. 4GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam, INTRODUCTION Germany. Our knowledge of detailed geomagnetic field secular variation in the Initial receipt: 4 November 2004 Acceptance: 23 February 2006 Southern Hemisphere is very limited during prehistoric times. A few Web publication: 1 December 2006 Ms 202SR-208 S.P. LUND ET AL. PALEOMAGNETIC SECULAR VARIATION AND CHRONOSTRATIGRAPHY 2 leomagnetic studies have developed reproducible Holocene paleomag- netic secular variation (PSV) records from Australia (Barton and McElhinny, 1981; Constable and McElhinny, 1985), New Zealand (Turner and Lillis, 1994), Argentina (Creer et al., 1983; Gogorza et al., 2000, 2002), and Antarctica (Brachfeld et al., 2000), but there is no re- producible detailed record of PSV from the entire Southern Hemisphere prior to ~18 ka. A gridwork of such records is essential for better under- standing the global space-time pattern of field variability between re- versals. Such a detailed knowledge of space-time field variability is particularly necessary to properly test newer, more realistic dynamo models of field variability (e.g., Kono and Roberts, 2002; Wicht and Ol- son, 2004) and better evaluate the relationship between magnetic field excursions and normal secular variation (e.g., Lund et al., 2001). During Leg 202, we recovered replicate high-resolution PSV records for the last ~70–150 ka from Sites 1233, 1234, and 1235 (Mix, Tiede- mann, Blum, et al., 2003). We present here a summary of the shipboard PSV data from replicate holes at Sites 1233 and 1234 for the last 50,000 yr. The PSV records from both sites contain evidence for two magnetic field excursions that are coeval with the Mono Lake (Benson et al., 2003) and Laschamp (Lund et al., in press) excursions, observed in the Northern Hemisphere. We also correlate the PSV records from Sites 1233 and 1234 and note their strong similarity even though they are lo- cated ~500 km apart. Finally, we integrate 27 radiocarbon dates recov- ered from Site 1233 to develop a revised chronostratigraphy at Sites 1233 and 1234 for the last 50,000 yr. PALEOMAGNETIC METHODS Shipboard paleomagnetic measurements were made on all cores re- covered during Leg 202. Individual cores, normally ~9.5 m in length, were cut into 1.5-m sections and split in half; each archive half was measured at 5-cm intervals on the shipboard 2-G Enterprises cryogenic magnetometer (Mix, Tiedemann, Blum, et al., 2003). The natural rema- nent magnetization (NRM) of each core segment was initially measured and then alternating-field (AF) demagnetization at one or two steps up to 25 mT was applied; the NRM was remeasured after each AF demagne- tization step. Individual core segments were not demagnetized at higher AF because the archive halves were to be further sampled for more detailed paleomagnetic studies after the completion of Leg 202. The limited shipboard AF demagnetization up to 25 mT, however, did a good job of removing a strong but soft viscous overprint that is often noted in cores collected during Ocean Drilling Program (ODP) legs (Mix, Tiedemann, Blum, et al., 2003; Lund et al., 2003). More detailed paleomagnetic measurements have been made in three selected 1.5-m intervals using U-channels that were collected from the centers of ar- chive core halves. These results, reported in a companion article (Lund et al., this volume), corroborate the shipboard paleomagnetic measure- ments presented here. All holes at each site have been correlated based on a variety of ship- board stratigraphic measurements and normalized to a common depth scale (meters composite depth [mcd]) for comparison (Mix, Tiedemann, Blum, et al., 2003). A composite splice section has been chosen from the replicate holes that best represents the observed variability at each site. These independent correlations were used to reconstruct the decli- nation record at each site. The declination records have been modified S.P. LUND ET AL. PALEOMAGNETIC SECULAR VARIATION AND CHRONOSTRATIGRAPHY 3 by first rotating the average declination for each core to 0° and then F1. Site 1233 PSV records, 0–30 slightly varying each core’s average declination to best match the decli- mcd, p. 11. A Composite PSV splice Hole 1233A Hole 1233B Hole 1233C Hole 1233D Hole 1233E nation trends between adjacent cores from each hole based on the ob- -80° -60° -60° -60° -60° -60° -60° -40° -20° 0 I1 260 I2 I3 1,180 I4 1,980 I5 3,820 5 I6 I7 5,040 I8 served declination variability in the other holes using the splice I9 5,590 I10 7,090 I11 10 8,780 I12 I13 I14 10,040 correlations. I16 I15 15 I18 I17 I19 12,260 I20 I21 20 I22 Sediment depth (mcd) 13,620 I23 I23 ‘ I24 I25 25 I26 17,240 I27 19,680 I28 Cal. yr BP 30 RESULTS B Composite PSV splice Hole 1233B Hole 1233C Hole 1233D Hole 1233E -20°0° 20° 0° 20° 0° 20° 0° 20° 0° 20° 0 260 D2 D1 D3 1,180 D4 1,980 D5 3,820 5 D6 D7 5,040 D8 5,590 D9 D10 7,090 10 8,780 Site 1233 Paleomagnetic Secular Variation Records D11 10,040 15 D12 D13 D14 12,260 D15 D16 20 Sediment depth (mcd) 13,620 D17 D17 ‘ D18 The AF demagnetized paleomagnetic directional records from Holes D19 25 D20 17,240 D21 D22 19,680 D23 Cal. yr BP D24 1233A–1233E (41.0°S, 74.45°W; 838 m water depth) are displayed in 30 D25 Figures F1, F2, F3, F4, and F5. The solid lines represent a seven-point running average of the directional data. Selected inclination (I1–I106) F2. Site 1233 PSV records, 30–60 and declination features (D1–D111) are noted based on their appear- mcd, p. 12. ance in records from multiple holes. Normally, directional features were A Composite PSV splice Hole 1233B Hole 1233C Hole 1233D Hole 1233E -80°-60° -60° -60° -60° -60° -40° 30 I29 I30 ( I31 ) 21,480 replicated in at least three holes, but selected features (in parentheses) ( I32 ) 35 I33 22,510 I34 I35 40 23,860 were only replicated in two holes. The boundaries between successive I36 I37 I38 26,050 I39 45 cores are evident in Figures F1, F2, F3, F4, and F5 as gaps in the direc- I39 ‘ 28,830 I40 29,510 I41 Sediment depth (mcd) 50 ( I42 ) 29,780 ( I43 ) tional records. The paleomagnetic directional record from the splice is ( I44 ) ( I44 ‘) 55 I45 I46 32,340 I47 I48 I49 36,360 I50 Cal. yr BP shown at the left in Figures F1, F2, F3, F4, and F5. The splice directional 60 B Composite PSV splice Hole 1233B Hole 1233C Hole 1233D Hole 1233E -20° 0° 20° 0°20° 0° 20° 0° 20° 0° 20° 40° 60° 80° 30 record represents our best composite record of the PSV recorded at Site D26 D27 21,480 35 D28 D29 22,510 1233, based on shipboard measurements. D30 40 D31 23,860 D32 D33 ° ° 26,050 B B D34 The inclinations at Site 1233 typically vary from 70 to 30 with an 45 D35 D35 ‘ 28,830 D36 29,510 D37 ° ° Sediment depth (mcd) 50 B D38 29,780 average near 55 . The observed average inclination is ~5 less than the Interval of D39 more uncertain D40 correlations 55 D41 32,340 D41 ‘ ° D42 expected axial-dipole inclination for the site latitude and ~10 less than D43 Excursion 3α 36,360 D44 Cal. yr BP 60 the average inclination expected for this site based on long-term lati- tude-dependent nondipole effects (ΔI anomaly) (e.g., Lund, 1993; Mer- rill et al., 1996). The slightly lower than expected inclinations are F3. Site 1233 PSV records, 60–90 probably a result of the presence of some residual viscous overprint mcd, p.
Load more

Recommended publications
  • PHANEROZOIC and PRECAMBRIAN CHRONOSTRATIGRAPHY 2016
    PHANEROZOIC and PRECAMBRIAN CHRONOSTRATIGRAPHY 2016 Series/ Age Series/ Age Erathem/ System/ Age Epoch Stage/Age Ma Epoch Stage/Age Ma Era Period Ma GSSP/ GSSA GSSP GSSP Eonothem Eon Eonothem Erathem Period Eonothem Period Eon Era System System Eon Erathem Era 237.0 541 Anthropocene * Ladinian Ediacaran Middle 241.5 Neo- 635 Upper Anisian Cryogenian 4.2 ka 246.8 proterozoic 720 Holocene Middle Olenekian Tonian 8.2 ka Triassic Lower 249.8 1000 Lower Mesozoic Induan Stenian 11.8 ka 251.9 Meso- 1200 Upper Changhsingian Ectasian 126 ka Lopingian 254.2 proterozoic 1400 “Ionian” Wuchiapingian Calymmian Quaternary Pleisto- 773 ka 259.8 1600 cene Calabrian Capitanian Statherian 1.80 Guada- 265.1 Proterozoic 1800 Gelasian Wordian Paleo- Orosirian 2.58 lupian 268.8 2050 Piacenzian Roadian proterozoic Rhyacian Pliocene 3.60 272.3 2300 Zanclean Kungurian Siderian 5.33 Permian 282.0 2500 Messinian Artinskian Neo- 7.25 Cisuralian 290.1 Tortonian Sakmarian archean 11.63 295.0 2800 Serravallian Asselian Meso- Miocene 13.82 298.9 r e c a m b i n P Neogene Langhian Gzhelian archean 15.97 Upper 303.4 3200 Burdigalian Kasimovian Paleo- C e n o z i c 20.44 306.7 Archean archean Aquitanian Penn- Middle Moscovian 23.03 sylvanian 314.6 3600 Chattian Lower Bashkirian Oligocene 28.1 323.2 Eoarchean Rupelian Upper Serpukhovian 33.9 330.9 4000 Priabonian Middle Visean 38.0 Carboniferous 346.7 Hadean (informal) Missis- Bartonian sippian Lower Tournaisian Eocene 41.0 358.9 ~4560 Lutetian Famennian 47.8 Upper 372.2 Ypresian Frasnian Units of the international Paleogene 56.0 382.7 Thanetian Givetian chronostratigraphic scale with 59.2 Middle 387.7 Paleocene Selandian Eifelian estimated numerical ages.
    [Show full text]
  • A Middle to Late Holocene Record of Arroyo Cut-Fill Events
    A MIDDLE TO LATE HOLOCENE RECORD OF ARROYO CUT-FILL EVENTS IN KITCHEN CORRAL WASH, SOUTHERN UTAH by William M. Huff A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Geology Approved: _________________________ _________________________ Dr. Tammy M. Rittenour Dr. Joel L. Pederson Major Professor Committee Member _________________________ _________________________ Dr. Patrick Belmont Dr. Mark R. McLellan Committee Member Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2013 ii Copyright © William M. Huff 2013 All Rights Reserved iii ABSTRACT A Middle to Late Holocene Record of Arroyo Cut-Fill Events in Kitchen Corral Wash, Southern Utah by William M. Huff, Master of Science Utah State University, 2013 Major Professor: Dr. Tammy M. Rittenour Department: Geology This study examines middle to late Holocene episodes of arroyo incision and aggradation in the Kitchen Corral Wash (KCW), a tributary of the Paria River in southern Utah. Arroyos are entrenched channels in valley-fill alluvium, and are capable of capturing decadal- to centennial- scale fluctuations in watershed hydrology as evidenced by the Holocene cut-fill stratigraphy recorded within near-vertical arroyo-channel walls. KCW has experienced both historic (ca. 1880-1920 AD) and prehistoric (Holocene) episodes of arroyo cutting and filling. The near- synchronous timing of arroyo cut-fill events between the Paria River and regional drainages over the last ~1 have led some researchers to argue that arroyo development is climatically driven. However, the influence of allogenic (climate-related) or autogenic (geomorphic threshold) forcings on arroyo dynamics are less clear.
    [Show full text]
  • Chronostratigraphy
    Dr. Maha Al-Hasson Stratigraphy Lectures Chronostratigraphy An elements of stratigraphy that deals with the relative time relations and ages of rock bodies. Chronostratigraphic classification: The organization of rocks into units on the basis of their age or time of origin. Inferential UNITS Groups of strata recognized as being formed during a specific interval of geological time .These units are not self-evident nor directly observable; Chronostratigraphic units: Are bodies of rocks(layered orunlayered), that were formed during a specified interval of a geologic time,they are bounded by synchronous horizons. synchronous horizons(chronohorizon):A stratigraphic surface or interface that is chronous, everywhere of the same age. position within chronostratigraphic unit is expressed by adjectives of position such as; basal, lower, middle, upper, etc.; position within a geochronologic unit is expressed by temporal adjectives such as: early, middle, late, etc. e.g.: lower Cambrian strata/Early Cambrian age middle Cambrian strata/ middle Cambrian strata upper Cambrian strata / late Cambrian strata. 1 Dr. Maha Al-Hasson Stratigraphy Lectures Ranks or types (Hierarchy) of inferential stratigraphic units Chronostratigraphic (Time rock) units Geochronologic (geologic time units) Eon Eonotheme Era Eratheme Period System Epoch Series Age Stage Chron Chronozone Many scientists believe systems & series are units of strata bounded by time surfaces. Stage & Age: all rocks that formed during an age.its a lowest rank of chronostratigraphic unit below series.Age: its' equivalent geochronologic unit, represents their times during rock' deposition . Series & Epochs: Series is achronostratigraphic unit ranking above a stage and below a system,subdivition of System,while Epoch its' equivalent geochronologic unit, representstheir times during rock deposition .
    [Show full text]
  • QUATERNARY SEA LEVEL CHANGE in the CARIBBEAN: the IMPLICATIONS for ARCHAEOLOGY Sherri Baker Littman
    QUATERNARY SEA LEVEL CHANGE IN THE CARIBBEAN: THE IMPLICATIONS FOR ARCHAEOLOGY Sherri Baker Littman ABSTRACT Human habitation of previously subaerial land surfaces is well documented. Geophysical and geological meth­ ods have been applied to elucidate the presence of associated geomorphic features. Records from varved sediments of bottom, anoxic waters yield clues to ancient climate records stored at the bottom of the Cariaco Basin. A sea level curve based upon uranium series (230TH) for Acropora palmata corals off the island of Barbados provides high precision chronology of sea level change since the last glacial maximum. The prograding delta of the Orinoco River has tremendously impacted sites on the island of Trinidad. Tectonic settings, isostasy, coastal hydrodynamics, fluvial and sediment discharge and accumulation rates, along with biostratigraphy and lithos- tratigraphy are necessary to build a valid chronostratigraphy when examining once subaerial archaeological sites. These combined methods provide valuable clues to the "peopling" of the Caribbean and should be employed when searching for prehistoric sites and evaluating settlement models. INTRODUCTION Evidence for Quaternary sea level change has been, at best, tenuous. Since scientific methods for determining sea level change are becoming more widely applied, this scenario is finally beginning to change. Studies show that although sea level has fluctuated eustatically, generalizations regarding specific regions, such as the Caribbean, cannot be made. Hence, this study will briefly examine the regional affects of sea level change on three areas within the Caribbean; the offshore area surrounding the island of Barbados, the Cariaco Basin (offshore Venezuela) and the Orinoco River delta and its affects on the island of Trinidad.
    [Show full text]
  • North American Stratigraphic Code1
    NORTH AMERICAN STRATIGRAPHIC CODE1 North American Commission on Stratigraphic Nomenclature FOREWORD TO THE REVISED EDITION FOREWORD TO THE 1983 CODE By design, the North American Stratigraphic Code is The 1983 Code of recommended procedures for clas- meant to be an evolving document, one that requires change sifying and naming stratigraphic and related units was pre- as the field of earth science evolves. The revisions to the pared during a four-year period, by and for North American Code that are included in this 2005 edition encompass a earth scientists, under the auspices of the North American broad spectrum of changes, ranging from a complete revision Commission on Stratigraphic Nomenclature. It represents of the section on Biostratigraphic Units (Articles 48 to 54), the thought and work of scores of persons, and thousands of several wording changes to Article 58 and its remarks con- hours of writing and editing. Opportunities to participate in cerning Allostratigraphic Units, updating of Article 4 to in- and review the work have been provided throughout its corporate changes in publishing methods over the last two development, as cited in the Preamble, to a degree unprece- decades, and a variety of minor wording changes to improve dented during preparation of earlier codes. clarity and self-consistency between different sections of the Publication of the International Stratigraphic Guide in Code. In addition, Figures 1, 4, 5, and 6, as well as Tables 1 1976 made evident some insufficiencies of the American and Tables 2 have been modified. Most of the changes Stratigraphic Codes of 1961 and 1970. The Commission adopted in this revision arose from Notes 60, 63, and 64 of considered whether to discard our codes, patch them over, the Commission, all of which were published in the AAPG or rewrite them fully, and chose the last.
    [Show full text]
  • Lithostratigraphic Unit
    E. F. McBride Geo. 420K Spring, 1999 NOTES ON STRATIGRAPHY FOR GEO420K TYPES OF STRATIGRAPHY Lithostratigraphy - Lithostratigraphic unit [Group, Formation, Member] - Lithodemic unit (intrusives, etc.) Pedostratigraphy - Pedostratigraphic unit Biostratigraphy - Zones Chronostratigraphy - Chronostratigraphic units [Period, Epoch, Age] Geochronostratigraphy - Geochronostratigraphic unit [System, Series, Stage] Magnetostratigraphy - Reversals, chrons Chemostratigraphy - Isotope zones Sequence Stratigraphy - Allostratigraphic units [Unconformity-bounded units] IMPORTANT SURFACES & TIME IMPLICATIONS 1) FAULTS, FRACTURES 2) UNCONFORMITIES = Buried erosion surfaces Physical erosion Biological erosion Chemical erosion Hiatus = amount of time record missing Diastem = small amount of rock missing Paraconformity " " " " Non-conformity: sedimentary rocks on top of igneous or metamorphics Disconformity: sediments conformable with sediments Angular unconformity: angular discordance 3) BEDDING Problem: how much time is represented by each bedding plane? FACIES Definitions: 1) Aspects of a rock that characterize it (minerals, fossils, color, etc). 2) Mappable, areally restricted part of a lithostratigraphic body that differs from its coeval equivalents. 3) A distinctive rock type that is characteristic of a particular environment: black shale facies, bioherm facies, channel facies, turbidite facies. 4) A body of rock distinguished on the basis of its fossil content: Ophiomorpha facies, Exogyra texana facies. BIOSTRATIGRAPHY PROCEDURE: plot range of every
    [Show full text]
  • Ch 72 (2009) 16–26
    Quaternary Research 72 (2009) 16–26 Contents lists available at ScienceDirect Quaternary Research journal homepage: www.elsevier.com/locate/yqres Evidence of NAO control on subsurface ice accumulation in a 1200 yr old cave-ice sequence, St. Livres ice cave, Switzerland Markus Stoffel a,b,c,⁎, Marc Luetscher d,e, Michelle Bollschweiler b,c, Frédéric Schlatter c a Climatic Change and Climate Impacts Group (C3i), Institute for Environmental Sciences, University of Geneva, Site de Batelle, chemin de Drize 7, CH-1227 Carouge-Geneva, Switzerland b Laboratory of Dendrogeomorphology (Dendrolab.ch), Institute of Geological Sciences, University of Berne, Baltzerstrasse 1+3, CH-3012 Berne, Switzerland c Department of Geosciences, Geography, University of Fribourg, chemin du Musée 4, CH-1700 Fribourg, Switzerland d Geology and Paleontology, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria e Swiss Institute for Speleology and Karst Studies (SISKA), P.O. Box 818, CH-2301 La Chaux-de-Fonds, Switzerland article info abstract Article history: Mid-latitude ice caves are assumed to be highly sensitive to climatic changes and thus represent a potentially Received 15 September 2008 interesting environmental archive. Establishing a precise chronology is, however, a prerequisite for the Available online 16 April 2009 understanding of processes driving the cave-ice mass balance and thus allows a paleoenvironmental interpretation. At St. Livres ice cave (Jura Mountains, Switzerland), subfossil trees and organic material are Keywords: abundant in the cave-ice deposit, therefore allowing the dating of individual ice layers. The dendrochrono- Cave ice logical analysis of 45 subfossil samples of Norway spruce (Picea abies (L.) Karst.) from the overhanging front of Sporadic permafrost 14 Dendrochronology the ice outcrop as well as the dating of seven wood samples with C dating allowed for a reconstruction of the Radiocarbon dating St.
    [Show full text]
  • Amino Acid Racemization of Planktonic Foraminifera
    AMINO ACID RACEMIZATION OF PLANKTONIC FORAMINIFERA: PRETREATMENT EFFECTS AND TEMPERATURE RECONSTRUCTIONS by Emily Watson A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Master of Science in Marine Studies Spring 2019 © 2019 Emily Watson All Rights Reserved AMINO ACID RACEMIZATION OF PLANKTONIC FORAMINIFERA: PRETREATMENT EFFECTS AND TEMPERATURE RECONSTRUCTIONS by Emily Watson Approved: __________________________________________________________ Katharina Billups, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: __________________________________________________________ Mark Moline, Ph.D. Chair of the Department of Marine Science and Policy Approved: __________________________________________________________ Estella Atekwana, Ph.D. Dean of the College of Earth, Ocean, and Environment Approved: __________________________________________________________ Douglas J. Doren, Ph.D. Interim Vice Provost for Graduate and Professional Education ACKNOWLEDGMENTS Very special thanks to my M.S. advisor Dr. Katharina Billups for providing me with this amazing opportunity and giving me her utmost support. Her willingness to give her time so generously has been indispensable during my Masters. She is my ultimate scientific role model. I am grateful for my collaborators from Northern Arizona University, Dr. Darrell Kaufman and Katherine Whitacre, who taught me the cleaning methods for this project and opened up their lab to me in January 2018. I would like to express my appreciation to Dr. Kaufman for his valuable and constructive suggestions during the planning and development of this research work. Data provided by Katherine was very valuable. I would also like to thank Dr. Doug Miller, and Dr. Andrew Wozniak, Dr. John Wehmiller from the University of Delaware for their assistance with this project.
    [Show full text]
  • Doc.Rero.Ch Populated and Industrialized Areas (E.G., Cecil Et Al., 2004)
    Published in "Quaternary Research 72(1): 16-26, 2009" which should be cited to refer to this work. Evidence of NAO control on subsurface ice accumulation in a 1200 yr old cave-ice sequence, St. Livres ice cave, Switzerland Markus Stoffel a,b,c,⁎, Marc Luetscher d,e, Michelle Bollschweiler b,c, Frédéric Schlatter c a Climatic Change and Climate Impacts Group (C3i), Institute for Environmental Sciences, University of Geneva, Site de Batelle, chemin de Drize 7, CH-1227 Carouge-Geneva, Switzerland b Laboratory of Dendrogeomorphology (Dendrolab.ch), Institute of Geological Sciences, University of Berne, Baltzerstrasse 1+3, CH-3012 Berne, Switzerland c Department of Geosciences, Geography, University of Fribourg, chemin du Musée 4, CH-1700 Fribourg, Switzerland d Geology and Paleontology, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria e Swiss Institute for Speleology and Karst Studies (SISKA), P.O. Box 818, CH-2301 La Chaux-de-Fonds, Switzerland Mid-latitude ice caves are assumed to be highly sensitive to climatic changes and thus represent a potentially interesting environmental archive. Establishing a precise chronology is, however, a prerequisite for the understanding of processes driving the cave-ice mass balance and thus allows a paleoenvironmental interpretation. At St. Livres ice cave (Jura Mountains, Switzerland), subfossil trees and organic material are abundant in the cave-ice deposit, therefore allowing the dating of individual ice layers. The dendrochrono- logical analysis of 45 subfossil samples of Norway spruce (Picea abies (L.) Karst.) from the overhanging front of the ice outcrop as well as the dating of seven wood samples with 14C dating allowed for a reconstruction of the St.
    [Show full text]
  • 1 Forthcoming in Philosophy of Science Calibration, Coherence
    Forthcoming in Philosophy of Science Calibration, Coherence, and Consilience in Radiometric Measures of Geologic Time Alisa Bokulich† Department of Philosophy Boston University [email protected] In 2012 the Geological Time Scale, which sets the temporal framework for studying the timing and tempo of all major geological, biological, and climatic events in Earth's history, had one-quarter of its boundaries moved in a wide-spread revision of radiometric dates. The philosophy of metrology helps us understand this episode, and it, in turn, elucidates the notions of calibration, coherence, and consilience. I argue that coherence testing is a distinct activity preceding calibration and consilience, and highlight the value of discordant evidence and tradeoffs scientists face in calibration. The iterative nature of calibration, moreover, raises the problem of legacy data. 1. Introduction Geochronology is the science of measuring geologic time through the dating of the materials of the Earth. One of the most important dating methods is radioisotope geochronology, which is the investigation of the age of these materials through the radioactive decay of the isotopes they contain. Radiometric methods, which have been around for a hundred years, provide one of most powerful tools for measuring absolute time. There are several different radioactive methods, based on different chemical elements, each with a different half-life, which makes it more or less suitable for measuring particular substances and particular periods of geologic time. The most well- known radiometric method is radiocarbon dating, which is based on the decay of 14C. However, because radiocarbon (14C) has a relatively short half-life, it can only reliably measure dates going back approximately 60,000 years, hardly making a dent in the measurement of geologic time.
    [Show full text]
  • Stratigraphy in the Oil Industry Ken Ratcliffe, Hafren Scientific Ltd., Andy Wilson Chemostrat Australia Ltd
    technology Stratigraphy in the Oil Industry Ken Ratcliffe, Hafren Scientific Ltd., Andy Wilson Chemostrat Australia Ltd. tratigraphy and the oil industry are stratigraphic thinking. The relationship between reduced to the description of innumerable, intricately intertwined, and have been the oil industry and the science of stratigraphy is localised successions of strata without it; an Sso ever since the early days of the a very healthy one and is truly symbiotic. apposite statement about stratigraphy in hydrocarbon exploitation. Stratigraphic the oil gas industry. Characterising single understanding forms the basis for all upstream The aim of this article is not to review stratigraphic well-bores is of little importance, but being activity from basin exploration through field methods, nor to provide a history of stratigraphy able extend that characterisation and place evaluation to reservoir development and in the industry; good quality reviews are available it in a time-context over an oil field or a production. Whilst the subject of stratigraphy elsewhere (e.g. Boggs, 1995; Catuneanu, prospective basin is without doubt the single in itself is fascinating and one that even non- 2006; Slatt, 2007; Ratcliffe and Zaitlin, 2010). most important building block for all later earth scientists will have been in contact Instead, this article examines why stratigraphic studies in hydrocarbon exploration. with when out and about in mountains, techniques that could be considered ‘academic’, on beaches or even driving through road suddenly (at least in geological terms) have “Standard” stratigraphic methods cuts (Figure 1), it is a subject that may well become relatively widely used tools in the oil in the industry have remained firmly bedded in the ivory and gas industry.
    [Show full text]
  • 3. Overview of Stratigraphy and Depositional Systems
    Basic Principles of Stratigraphy and Depositional Systems I. INTRODUCTION A. Stratigraphy: the study of the geologic rock record in the context of geologic time. 1. Geologic Rock Record: analogous to a tape recording in which some historical events are preserved and recorded, others have been erased, and still others were not taped at all a. Referred to as "Stratigraphic Record": originally involved the study of "layered" sedimentary rocks and the fossil record. (1) Advances in sensing techniques (radiometric dating, seismic analysis, paleomagnetism) have expanded the study of stratigraphy and rock record to the realm of igneous and metamorphic rock sequences 2. Geologic Time: abstract concept of continuous linear time from earth's origins to present day (portions of which are preserved in the rock record, and portions of which are not) a. Time record vs. Rock Record 3. The study of Stratigraphy represents an attempt to correlate the relative sequence of observations from the rock record, with that of historical/linear time. B. Historical Geology: Use of the stratigraphic record to derive historical time record and physical/biological evolution of the earth. 1. I.e. examining the rock record to deduce the natural history of the time record. C. Sedimentology: study of the processes and products of the near-surface environment of the earth 1. Sedimentology outgrowth of stratigraphy, historical geology a. Stratigraphy originally based on layered sedimentary rocks and the fossils contained within. b. Sediments accumulate as horizontal layers of particles under the force of gravity, "layer cake" approach to geology and interpretation of the rock record. 20 I.
    [Show full text]