DOCSLIB.ORG

Geochronology: Linking the Isotopic Record with Petrology and Textures - an Introduction

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geochronology: Linking the Isotopic Record with Petrology and Textures - an Introduction Downloaded from http://sp.lyellcollection.org/ by guest on September 26, 2021 Geochronology: linking the isotopic record with petrology and textures - an introduction DEREK VANCE 1'2, WOLFGANG MULLER 3 & IGOR M. VILLA 4 1Department of Geology, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK (e-mail: [email protected]) 2present address: Department of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1R J, UK 3Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia (e-mail: wolfgang.mueller@ anu. edu. au) 4 Isotopengeologte, Erlachstrasse 9a, 3012 Bern, Switzerland and Dipartimento di Scienze Geologiche e Geotecnologie, Universitgt di Milano-Bicocca, 20126 Milano, Italy (e-mail: [email protected]) Abstract: One of the key aims of geochronology, and the subject of the papers in this Special Publication, is the linkage of isotopic ages to petrological and textural information. A close link between the two types of information greatly improves the constraints available from geochronology on the nature and rates of lithospheric processes such as metamorphism and deformation. There have been several key advances in this area over the past 10-20 years, relating to increased precision and accuracy of isotopic ages but also, and crucially, to the spatial resolution available to geochronologists. This resolution now approaches that on which petrological, chemical and textural information is obtained. We also, in this introduction, identify the barriers that have impeded further progress, which relate both to technical issues as well as to problems of understanding. Finally we set the papers in this volume in the context of the preceding discussion and outline the key ways in which these papers point towards further progress in the future. Time has always been recognized as a key variable the emphasis of the two papers is slightly differ- in the Earth sciences, both in its own right and ent, with Mtiller (2003) concentrating largely on through the constraints that chronological infor- new in-situ techniques and their resulting pro- mation provides on the rates of, and hence spects, whereas here we give a broader overview the physical mechanisms for, Earth processes. In of the whole subject, with more emphasis on the the study of the dynamics of the Earth's litho- dating of high temperature processes and the sphere during orogenesis and metamorphism, one interrelated achievements of both modelling and of the key requirements of any time datum is that experimental work in petrology. We also aim to it is relatable in a straightforward manner to other highlight some general issues that are dealt with geological information, such as data on tempera- in specifics in the subsequent contributions. First, ture, pressure and deformation. It is only through we give a brief account of the progress that has this linkage that chronometric information can been made over the past two decades in our ability achieve its full potential in contributing to progress to extract the timing and conditions of deformation in understanding the dynamics of mountain belts and metamorphism from minerals and in the and other metamorphic settings. This linkage interpretive framework in which these new data are is the focus of the set of papers in this volume, analysed. Next we identify three key barriers that which emanate from a special symposium at the initially impeded further progress and which have 2002 Goldschmidt Conference, held at Davos, been and continue to be the subjects of intensive Switzerland. The topic under discussion has been research eflbrt. Finally, we discuss ways that are the subject of a review by one of us recently being developed to surmount these barriers, with (Mtiller 2003). Inevitably, there is some overlap particular reference to the contributions in this between this paper and Miiller (2003). However, volume. From: VANCE, D., MIDLLER,W., (~c VILLA, I. M. (eds) 2003. Geochronology: Linking the Isotopic Record with Petrology and Textures. Geological Society, London, Special Publications, 220, 1-24. 0305-8719/03/$15 9 The Geological Societyof London 2003. Downloaded from http://sp.lyellcollection.org/ by guest on September 26, 2021 2 D. VANCE ETAL Progress in quantifying rates of thermal, largely been driven by technology with the advent, baric and structural evolution of first, of multi-collector mass spectrometers (e.g. Esat 1984; for an early geochronological use see the lithosphere Vance & O'Nions 1990) and techniques for in-situ The last three decades have seen enormous pro- dating of metamorphic mineral phases, such as ion gress in our understanding of metamorphic belts microprobe (e.g. Compston et al. 1984; Harrison in general. This progress has its origins in et al. 1995) and laser ablation methods (Horn et al. three main fields of activity. Firstly, there has 2000; Ballard et al. 2001; Kosler et al. 2001; Foster been a dramatic expansion in the number and et al. 2002). the quality of experimental constraints on the The two steps forward described above have pressure and temperature conditions of formation largely been powered by technology and data. of key metamorphic minerals, as evidenced by These newly available databases provided the the increasing variety of mineral end-members initial impetus for developments in the third main incorporated in databases of mineral thermody- field which has led progress in understanding namic properties (e.g. Holland & Powell 1998). orogenic belts: the numerical simulation of the The acquisition of this new experimental mechanical and thermal adjustments that are the database has gone hand-in-hand with advances consequences of orogenesis and the causes of in our ability to simulate the phase equilibria of metamorphism. The application of analytical metamorphic rocks using computer models (e.g. solutions of heat transport equations to one- Spear 1988; Berman 1991; Powell et al. 1998). dimensional models of metamorphic belts in The pioneering predictive modelling of mineral the 1970s (Bickle et al. 1975), was followed by phase equilibria in the 1970s was restricted to more general one-dimensional models involving simple chemical systems like KFMASH and was numerical solutions (England & Thompson largely semi-quantitative (e.g. Hensen 1971; 1984), and has culminated more recently in the Thompson et al. 1977). In the last 10-15 years, development of two-dimensional models that on the other hand, the quantitative analysis of more fully simulate the temperature and defor- chemical systems that more realistically match mation fields in orogenic belts (Huerta et al. real silicate rocks has been made possible by an 1999; Jamieson et al. 2002). These models were improved knowledge of basic thermodynamic initially designed as an interpretive framework quantities and activity models for many more for thermobarometric, chronometric and struc- phases and mineral chemical end-members (e.g. tural data, but they also make predicitions about Holland & Powell 1998). It is also more common the pressure-temperature-deformation-time to view metamorphic events in terms of P-T-X histories of deeply buried rocks (and the surface relations (Berman 1991; Kerrick 1991) in development of orogenic belts) that the newly chemically open systems rather than as simple available databases can be used to test. heating of a closed system (J~iger et al. 1967). One of the key requirements that the numeri- These advances have greatly improved our cal models make of pressure-temperature- ability to model the temperature and depths of deformation-time data is that the time constraint burial of exhumed packets of lithosphere presently is not only precise and accurate but that it can be exposed at the surface of the Earth. Significantly, easily related to the other three variables (e.g. they have also allowed segments of pressure- Thompson & England 1984). In other words, temperature paths to be extracted from rocks. These chronological constraints can add immeasurably latter are key inputs to thermal and mechanical more to our understanding of metamorphism if models that seek to clarify the plate tectonic they can be linked unequivocally to P-T-X-d settings of orogenesis (e.g. England & Thompson data. Moreover, one of the key outputs of 1984; Huerta et al. 1999; Jamieson et al. 2002). A numerical models is P-T-X-d evolution. That second key input to such models is time, and the being the case, a deep understanding of the constraints that chronometric information provides portion of a P-T-X-d history when different on the rates at which burial, heating and deforma- minerals, or parts of them, record time, pressure, tion occur. This is where the second major advance temperature and deformation, is clearly essential in this field has occurred. The source of if these types of data are to test such models. The information on the chronology of metamorphism recent attempts at achieving such an under- is, of course, radiogenic isotope geology and the standing are the subject of many of the contri- last three decades have also seen unprecedented butions in this book. As these articles make advances in our ability to measure the isotope abundantly clear, however, the linkage of a time composition of radiogenic elements, both in the constraint obtained from radiogenic isotopes in precision available and in the quantity of material minerals to other types of information, such as required for the analyses. This leap forward has petrological and structural data, is not always Downloaded from http://sp.lyellcollection.org/ by guest on September 26, 2021 PETROLOGY AND TEXTURES - AN INTRODUCTION 3 straightforward. The reasons why are discussed structural evolution. This difficulty arises because in the next section. It is important to note that the datable minerals are present as accessory while faster analytical protocols have increased phases whose relationship to the main rock the sample throughput, this does not per se texture is often equivocal but, more importantly, guarantee an improved understanding of isotopic because their chemistry, involving silicates or ages.
Load more

Recommended publications
  • Comparison of Detrital Zircon U-Pb and Muscovite 40Ar/39Ar Ages in the Yangtze Sediment: Implications for Provenance Studies
    minerals Article Comparison of Detrital Zircon U-Pb and Muscovite 40Ar/39Ar Ages in the Yangtze Sediment: Implications for Provenance Studies Xilin Sun 1,2,* , Klaudia F. Kuiper 2, Yuntao Tian 1, Chang’an Li 3, Zengjie Zhang 1 and Jan R. Wijbrans 2 1 School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou 510275, China; [email protected] (Y.T.); [email protected] (Z.Z.) 2 Department of Earth Sciences, Cluster Geology and Geochemistry, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands; [email protected] (K.F.K.); [email protected] (J.R.W.) 3 School of Geography and Information Engineering, China University of Geosciences, Wuhan 430074, China; [email protected] * Correspondence: [email protected] Received: 30 June 2020; Accepted: 17 July 2020; Published: 20 July 2020 Abstract: Detrital zircon U-Pb and muscovite 40Ar/39Ar dating are useful tools for investigating sediment provenance and regional tectonic histories. However, the two types of data from same sample do not necessarily give consistent results. Here, we compare published detrital muscovite 40Ar/39Ar and zircon U-Pb ages of modern sands from the Yangtze River to reveal potential factors controlling differences in their provenance age signals. Detrital muscovite 40Ar/39Ar ages of the Major tributaries and Main trunk suggest that the Dadu River is a dominant sediment contributor to the lower Yangtze. However, detrital zircon data suggest that the Yalong, Dadu, and Min rivers are the most important sediment suppliers. This difference could be caused by combined effects of lower reaches dilution, laser spot location on zircons and difference in closure temperature and durability between muscovite and zircon.
    [Show full text]
  • Apatite Thermochronology in Modern Geology
    Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 Apatite thermochronology in modern geology F. LISKER1*, B. VENTURA1 & U. A. GLASMACHER2 1Fachbereich Geowissenschaften, Universita¨t Bremen, PF 330440, 28334 Bremen, Germany 2Institut fu¨r Geowissenschaften, Ruprecht-Karls-Universita¨t Heidelberg, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany *Corresponding author (e-mail: fl[email protected]) Abstract: Fission-track and (U–Th–Sm)/He thermochronology on apatites are radiometric dating methods that refer to thermal histories of rocks within the temperature range of 408–125 8C. Their introduction into geological research contributed to the development of new concepts to interpreting time-temperature constraints and substantially improved the understanding of cooling processes within the uppermost crust. Present geological applications of apatite thermochronological methods include absolute dating of rocks and tectonic processes, investigation of denudation histories and long-term landscape evolution of various geological settings, and basin analysis. Thermochronology may be described as the the analysis of radiation damage trails (‘fission quantitative study of the thermal histories of rocks tracks’) in uranium-bearing, non-conductive using temperature-sensitive radiometric dating minerals and glasses. It is routinely applied on the methods such as 40Ar/39Ar and K–Ar, fission minerals apatite, zircon and titanite. Fission tracks track, and (U–Th)/He (Berger & York 1981). are produced continuously through geological time Amongst these different methods, apatite fission as a result of the spontaneous fission of 238U track (AFT) and apatite (U–Th–Sm)/He (AHe) atoms. They are submicroscopic features with an are now, perhaps, the most widely used thermo- initial width of approximately 10 nm and a length chronometers as they are the most sensitive to low of up to 20 mm (Paul & Fitzgerald 1992) that can temperatures (typically between 40 and c.
    [Show full text]
  • Closure Temperature of (U-Th)/He System in Apatite Obtained from Natural Drillhole Samples in the Tarim Basin and Its Geological Significance
    Article Geology September 2012 Vol.57 No.26: 34823490 doi: 10.1007/s11434-012-5176-1 SPECIAL TOPICS: Closure temperature of (U-Th)/He system in apatite obtained from natural drillhole samples in the Tarim basin and its geological significance CHANG Jian1,2 & QIU NanSheng1,2* 1 State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China; 2 Basin and Reservoir Research Center, China University of Petroleum, Beijing 102249, China Received February 27, 2012; accepted March 27, 2012; published online May 15, 2012 The apatite (U-Th)/He thermochronometry has been used to study the tectono-thermal evolution of mountains and sedimentary basins for over ten years. The closure temperature of helium is important for the apatite (U-Th)/He thermochronometry and has been widely studied by thermal simulation experiments. In this paper, the apatite He closure temperature was studied by estab- lishing the evolutionary pattern between apatite He ages and apatite burial depth based on examined apatite He ages of natural samples obtained from drillholes in the Tarim basin, China. The study showed that the apatite He closure temperature of natural samples in the Tarim basin is approximately 88±5°C, higher than the result (~75°C) obtained from the thermal simulation exper- iments. The high He closure temperature resulted from high effective uranium concentration, long-term radiation damage accu- mulation, and sufficient particle radii. This study is a reevaluation of the conventional apatite He closure temperature and has a great significance in studying the uplifting events in the late period of the basin-mountain tectonic evolution, of which the uplift- ing time and rates can be determined accurately.
    [Show full text]
  • 4. Thermochronology – Techniques and Methods
    4. Thermochronology – Techniques and Methods 4.1 Introduction to thermochronology Thermochronology is the study of dating the cooling of rocks through exhumation. In its simplest form, thermochronology can be considered to date the moment when a mineral passes through a specific closure temperature (Tc) (Dodson, 1973). Minerals have different closure temperatures and so by using a suite of thermochronometers on a single sample, its cooling path through the crust can be reconstructed. The minerals and closure temperatures available for use are illustrated in figure 4.1. The highest temperature chronometers have closure temperatures in excess of 750oC (U-Pb in zircon). These higher temperature chronometers such as the U-Pb system in zircon are used to date, for example, Archean gneiss terrains, due to the unlikely nature of them having been reset, with depths required for reset at ~30 km (assuming a 25oCkm-1 geothermal gradient). This study focuses on the low temperature thermochronometers which may allow the geomorphic signature of the landscape to become etched into the thermochronometric record. Two principal low temperature thermochronometers are used in this study, apatite fission track analysis (AFT) and apatite (U-Th)/He analysis (AHe). These are the lowest temperature chronometers that are known about in sufficient detail and calibrated well enough to make them usable. The low temperature thermochronometers may be used in a variety of ways, but one of their principal uses and that used in this study is to determine the temperature-time history of samples. As an extension to this they may also be used to determine exhumation rates by making some assumptions and for the higher temperature chronometers, to date the timing of formation of the rock/mineral in question.
    [Show full text]
  • Apatite (U^Th)/He Thermochronometry: Methods and Applications to Problems in Tectonic and Surface Processes
    Earth and Planetary Science Letters 206 (2003) 1^14 www.elsevier.com/locate/epsl Frontiers Apatite (U^Th)/He thermochronometry: methods and applications to problems in tectonic and surface processes Todd A. Ehlers Ã, Kenneth A. Farley California Institute of Technology, Division of Geological and Planetary Sciences, MC 100-23, Pasadena, CA91125, USA Received 11 July 2002; received in revised form 1 October 2002; accepted 5 November 2002 Abstract In the last decade apatite (U^Th)/He thermochronometry has emerged as an important tool for quantifying the cooling history of rocks as they pass through the upper 1^3 km of the crust. The low closure temperature of this technique (V70‡C) has gained the interest of geomorphologists and tectonocists because it is applicable to interdisciplinary studies in landform evolution, structural geology, and geodynamics. We discuss current analytical techniques, the temperature calibration of the method, and sample quality considerations. Results from 1D, 2D and 3D thermo-kinematic numerical models are used to illustrate applications of He thermochronometry to problems in tectonics and landform evolution. ß 2002 Elsevier Science B.V. All rights reserved. Keywords: apatite; (U^Th)/He; thermochronometry; surface processes; tectonics; numerical modeling 1. Introduction chronometry. The focus on apatite arises from its ubiquity and moderately high U and Th content, A recent resurgence of interest in dating miner- but more importantly because He accumulation in als via 4He ingrowth has been driven by an im- apatite occurs only at temperatures below V70^ proved understanding of the behavior of He in 75‡C [9]. At higher temperatures di¡usion re- minerals [1^4], development of robust analytical moves He as fast as it is produced by decay.
    [Show full text]
  • Fission Track Constraints on Exhumation and Extensional Faulting in Southwest Nevada and Eastern California, U.S.A
    FISSION TRACK CONSTRAINTS ON EXHUMATION AND EXTENSIONAL FAULTING IN SOUTHWEST NEVADA AND EASTERN CALIFORNIA, U.S.A. Prepared for U.S. Nuclear Regulatory Commission Contract NRC–02–07–006 Prepared by David A. Ferrill,1 Alan P. Morris,1 John A. Stamatakos,2 Deborah J. Waiting,2 Raymond A. Donelick,3 Ann E. Blythe4 1Department of Earth, Material, and Planetary Sciences Southwest Research Institute® San Antonio, Texas 2Center for Nuclear Waste Regulatory Analyses San Antonio, Texas 3Apatite to Zircon, Inc. Viola, Idaho 4Department of Geology Occidental College Los Angeles, California September 2011 ABSTRACT Eastern California and southwestern Nevada is an area of Tertiary and Quaternary extensional and dextral transtensional deformation. We use zircon and apatite fission-track thermochronology to study the distribution and timing of tectonic exhumation resulting from extensional and transtensional detachment faulting in this area. Samples were collected from outcrops around Yucca Flat and Frenchman Flat, the Striped Hills, Mount Stirling, Resting Spring Range, Bare Mountain, Bullfrog Hills, and the eastern margin of the Funeral Mountains. To constrain timing of exhumation associated with crustal-scale normal faulting, sampling efforts were focused on Paleozoic and Precambrian clastic sedimentary and metasedimentary rocks of the Stirling Quartzite, Wood Canyon Formation, Zabriskie Quartzite, Eureka Quartzite, and Eleana Formation. Sixty-nine new apatite and zircon fission-track cooling ages from 50 samples, analyzed in conjunction with published fission-track data from the region, indicate a distinct population of young (Miocene) fission-track ages and a population of irregularly distributed older (pre-Miocene) fission-track ages. Miocene (young population) fission track ages young westwards—indicating westward migration of the cooling front, consistent with well-documented Miocene extension of the Basin and Range.
    [Show full text]
  • (U–Th)/He Thermochronometry Using a Radiation Damage Accumulation and Annealing Model
    Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 73 (2009) 2347–2365 www.elsevier.com/locate/gca Apatite (U–Th)/He thermochronometry using a radiation damage accumulation and annealing model Rebecca M. Flowers a,*, Richard A. Ketcham b, David L. Shuster c, Kenneth A. Farley d a Department of Geological Sciences, University of Colorado at Boulder, 2200 Colorado Ave., UCB 399, Boulder, CO 80309, USA b Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA c Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA d Department of Geological and Planetary Sciences, California Institute of Technology, MS 170-25, Pasadena, CA 91125, USA Received 13 October 2008; accepted in revised form 21 January 2009; available online 11 March 2009 Abstract Helium diffusion from apatite is a sensitive function of the volume fraction of radiation damage to the crystal, a quantity that varies over the lifetime of the apatite. Using recently published laboratory data we develop and investigate a new kinetic model, the radiation damage accumulation and annealing model (RDAAM), that adopts the effective fission-track density as a proxy for accumulated radiation damage. This proxy incorporates creation of crystal damage proportional to a-production from U and Th decay, and the elimination of that damage governed by the kinetics of fission-track annealing. The RDAAM is a version of the helium trapping model (HeTM; Shuster D. L., Flowers R. M. and Farley K. A. (2006) The influence of nat- ural radiation damage on helium diffusion kinetics in apatite. Earth Planet.
    [Show full text]
  • U-Th)/He Datasets
    minerals Article A Framework for Evaluating Variation in (U-Th)/He Datasets Francis J. Sousa 1,* and Kenneth A. Farley 2 1 College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA 2 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA; [email protected] * Correspondence: [email protected] Received: 11 November 2020; Accepted: 8 December 2020; Published: 10 December 2020 Abstract: This paper presents a framework for evaluating variation in (U-Th)/He datasets. The framework is objective, repeatable, and based on compatibility of thermal histories derived from individual (U-Th)/He dates. The structure of this new method includes three fundamental steps. First, the allowable thermal history of each individual grain is quantitatively constrained with a model. Second, the thermal histories of all grains from a sample are visualized on the same axes. Third, the compatibility of the allowable thermal histories of each individual grain is evaluated. This allows a user to assess whether variation among single grain dates can plausibly be explained (referred to here as legitimate) or not (illegitimate). Additionally, this methodology allows for accurate representation of the impact that illegitimate variation has on the thermal history constraints of a sample. We demonstrate the application of this new framework using a variety of examples from the literature, as well as with synthetic data. Modeling presented here is executed using the modeling software QTQt (version 5.6.0) and the He diffusion kinetics based on the radiation damage accumulation and annealing model, but the framework is designed to be easily adaptable to any modeling software and diffusion parameters.
    [Show full text]
  • Grain-Size Effects on the Closure Temperature of White Mica in A
    Tectonophysics 674 (2016) 210–226 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Grain-size effects on the closure temperature of white mica in a crustal-scale extensional shear zone — Implications of in-situ 40Ar/39Ar laser-ablation of white mica for dating shearing and cooling (Tauern Window, Eastern Alps) Andreas Scharf a,b,⁎,1,MarkR.Handya, Stefan M. Schmid a,c, Silvia Favaro a, Masafumi Sudo d, Ralf Schuster e, Konrad Hammerschmidt a a Department of Earth Sciences, Freie Universität Berlin, Malteserstrasse 74-100, 12249 Berlin, Germany b Department of Earth Science, Sultan Qaboos University, P.O. Box 36, Al-Khoudh, P.C. 123 Muscat, Oman c Institute of Geophysics, Eidgenössische Technische Hochschule (ETH), Sonneggstrasse 5, 8092 Zürich, Switzerland d Institute of Earth and Environmental Science, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany e Geologische Bundesanstalt, Neulinggasse 38, 1030 Wien, Austria article info abstract Article history: In-situ 40Ar/39Ar laser ablation dating of white-mica grains was performed on samples from the footwall of a Received 15 February 2015 crustal-scale extensional fault (Katschberg Normal Fault; KNF) that accommodated eastward orogen-parallel dis- Received in revised form 10 December 2015 placement of Alpine orogenic crust in the eastern part of the Tauern Window. This dating yields predominantly Accepted 5 February 2016 cooling ages ranging from 31 to 13 Myr, with most ages clustering between 21 and 17 Myr. Folded white micas Available online 24 February 2016 that predate the main Katschberg foliation yield, within error, the same ages as white-mica grains that overgrow Keywords: this foliation.
    [Show full text]
  • Tectonic History of the South Tannuol Fault Zone (Tuva Region of the Northern Central Asian Orogenic Belt, Russia): Constraints from Multi-Method Geochronology
    minerals Article Tectonic History of the South Tannuol Fault Zone (Tuva Region of the Northern Central Asian Orogenic Belt, Russia): Constraints from Multi-Method Geochronology Evgeny Vetrov 1,*, Johan De Grave 2, Natalia Vetrova 1, Fedor Zhimulev 1, Simon Nachtergaele 2 , Gerben Van Ranst 2 and Polina Mikhailova 3 1 Sobolev Institute of Geology and Mineralogy, Siberian Branch Russian Academy of Sciences, Koptuga ave. 3, 630090 Novosibirsk, Russia; [email protected] (N.V.); [email protected] (F.Z.) 2 Department of Geology, Ghent University, Krijgslaan 281.S8, WE13, 9000 Ghent, Belgium; [email protected] (J.D.G.); [email protected] (S.N.); [email protected] (G.V.R.) 3 Siberian Research Institute of Geology, Geophysics and Mineral Resources, Krasniy ave. 35, 630099 Novosibirsk, Russia; [email protected] * Correspondence: [email protected] or [email protected]; Tel.: +7-913-770-75-10 Received: 12 November 2019; Accepted: 6 January 2020; Published: 9 January 2020 Abstract: In this study, we present zircon U/Pb, plagioclase and K-feldspar 40Ar/39Ar and apatite fission track (AFT) data along the South Tannuol Fault Zone (STFZ). Integrating geochronology and multi-method thermochronology places constraints on the formation and subsequent reactivation of the STFZ. Cambrian (~510 Ma) zircon U/Pb ages obtained for felsic volcanic rocks date the final stage of STFZ basement formation. Ordovician (~460–450 Ma) zircon U/Pb ages were obtained for felsic rocks along the structure, dating their emplacement and marking post-formational local magmatic activity along the STFZ. 40Ar/39Ar stepwise heating plateau-ages (~410–400 Ma, ~365 and ~340 Ma) reveal Early Devonian and Late Devonian–Mississippian intrusion and/or post-magmatic cooling episodes of mafic rocks in the basement.
    [Show full text]
  • Fission Track Dating Generally Uses Uranium Rich Miner- Als
    Geol. 655 Isotope Geochemistry Lecture 14 Spring 2003 GEOCHRONOLOGY X: FISSON TRACK DATING INTRODUCTION As we have already noted, a frac- tion of uranium atoms undergo spontaneous fission rather than al- pha decay. The sum of the masses of the fragments is less than that of the parent U atom: this difference re- flects the greater binding energy of the fragments. The missing mass has been converted to kinetic energy of the fission fragments. Typically, this energy totals about 200 MeV, a con- siderable amount of energy on the atomic scale. The energy is depos- Figure 14.1. Fission tracks in a polished and etched ited in the crystal lattice through zircon. Photo courtesy J. M. Bird. which the fission fragments pass by stripping electrons from atoms in the crystal lattice. The ionized atoms repel each other, disordering the lattice and producing a small channel and a wider stressed region in the crystal. The damage is visible as tracks seen with an electron microscope operating at magnifications of 50,000¥ or greater. However, the stressed region is more readily attacked and dissolved by acid; so by acid etching the tracks can be enlarged to the point where they are visible under the optical microscope. Figure 14.1 is an example. Because fission is a rare event in any case, fission track dating generally uses uranium rich miner- als. Most work has been done on apatites, but sphene and zircon are also commonly used. Fission tracks will anneal, or self-repair, over time. The rate of annealing is vanishingly small at room temperature, but increases with temperature and becomes significant at geologically low to moderate temperatures.
    [Show full text]
  • Petrochronology of Monazite and Zircon in Ultra-High Temperature Granulite from Rogaland, Norway Antonin Laurent
    Petrochronology of monazite and zircon in ultra-high temperature granulite from Rogaland, Norway Antonin Laurent To cite this version: Antonin Laurent. Petrochronology of monazite and zircon in ultra-high temperature granulite from Rogaland, Norway. Earth Sciences. Université Paul Sabatier - Toulouse III, 2016. English. NNT : 2016TOU30290. tel-01686377 HAL Id: tel-01686377 https://tel.archives-ouvertes.fr/tel-01686377 Submitted on 17 Jan 2018 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. 5)µ4& &OWVFEFMPCUFOUJPOEV %0$503"5%&-6/*7&34*5²%&506-064& %ÏMJWSÏQBS Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier) 1SÏTFOUÏFFUTPVUFOVFQBS Antonin LAURENT le mardi 8 novembre 2016 5JUSF Étude pétrologique et chronométrique (U–Th–Pb) de la monazite et du zircon dans les granulites de ultra-haute température du Rogaland, Norvège ²DPMF EPDUPSBMF et discipline ou spécialité ED SDU2E : Sciences de la Terre et des Planètes Solides 6OJUÏEFSFDIFSDIF Géosciences Environnement Toulouse – UMR 5563 %JSFDUFVSUSJDF T EFʾÒTF Mme Stéphanie Duchene (Directrice) Mme Anne-Magali Seydoux-Guillaume (Co-directrice) M. Bernard Bingen (Co-encadrant) Jury : M. Philippe GONCALVES Maître de conférences Rapporteur M. Simon HARLEY Professeur des universités Rapporteur M. Fernando CORFU Professeur des universités Examinateur M.
    [Show full text]