Thomas Spring Thesis (PDF 7MB)
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Pillow Basalts from the Mount Ada Basalt, Warrawoona Group, Pilbara Craton: Implications for the Initiation of Granite-Greenstone Terrains D
Goldschmidt2015 Abstracts Pillow basalts from the Mount Ada basalt, Warrawoona group, Pilbara Craton: Implications for the initiation of granite-greenstone terrains D. T. MURPHY1*, J. TROFIMOVS1, R. A. HEPPLE1, D. WIEMER1, A. I. S. KEMP2 AND A. H. HICKMAN3 1Earth, Environmental and Biological Sciences, Queensland University of Technology, 4001, Australia (correspondence: [email protected]) 2School of Earth and Environment, The University of Western Australia, 6009, Australia 3Department of Mines and Petroleum, Western Australia The Pilbara Craton represents the archetypal Archean granite-greenstone terrain in which mafic volcanic dominated supercrustals are intruded by granitic domes. This crustal morphology reflects distinct tectonic settings that formed in a hotter early Earth. The ambient temperature in the Paleoarchean mantle is estimated to be 1600oC [1] and corresponds with the liquidus temperature of Barberton komatiites [2]. In the Paleoarchean mantle a pyrolite composition at depths of less than 100 km is expected to melt and generate ultramafic magmas. Here we present volcanology, petrology and geochemistry data of well-preserved basaltic lavas ascribed to the Mount Ada Basalt, Warrawoona Group from the Doolena Gap Greenstone Belt. The Mount Ada Basalt was coeval with the Callina plutonic event that marks the initiation of dome formation in the Pilbara Craton [3]. The Doolena Gap sequence is exclusively pillow basalts with MgO < 10%. Isotopically the basalts are indistinguishable from contemporary non-chondritic Bulk Earth (εNd, 1.0 ± 0.2 and εHf, 2.3 ± 0.2). Here we address the implications of Paleoarchean basalts with MgO% < 10 derived from melting of a source indistinguishable from non-chondritic Bulk Silicate Earth to the initiation and subsequent evolution of the Pilbara Craton. -
12.007 Geobiology Spring 2009
MIT OpenCourseWare http://ocw.mit.edu 12.007 Geobiology Spring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. Geobiology 2009 Lecture 10 The Antiquity of Life on Earth Homework #5 Topics (choose 1): Describe criteria for biogenicity in microscopic fossils. How do the oldest describes fossils compare? Use this to argue one side of the Brasier-Schopf debate OR What are stromatolites; where are they found and how are they formed? Articulate the two sides of the debate on antiquity and biogenicity. Up to 4 pages, including figures. Due 3/31/2009 Need to know • How C and S- isotopic data in rocks are informative about the advent and antiquity of biogeochemical cycles • Morphological remains and the antiquity of life; how do we weigh the evidence? • Indicators of changes in atmospheric pO2 • A general view of the course of oxygenation of the atm-ocean system Readings for this lecture Schopf J.W. et al., (2002) Laser Raman Imagery of Earth’s earliest fossils. Nature 416, 73. Brasier M.D. et al., (2002) Questioning the evidence for Earth’s oldest fossils. Nature 416, 76. Garcia-Ruiz J.M., Hyde S.T., Carnerup A. M. , Christy v, Van Kranendonk M. J. and Welham N. J. (2003) Self-Assembled Silica-Carbonate Structures and Detection of Ancient Microfossils Science 302, 1194-7. Hofmann, H.J., Grey, K., Hickman, A.H., and Thorpe, R. 1999. Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia. Geological Society of America, Bulletin, v. 111 (8), p. -
VAALBARA and TECTONIC EFFECTS of a MEGA IMPACT in the EARLY ARCHEAN 3470 Ma
Large Meteorite Impacts (2003) 4038.pdf VAALBARA AND TECTONIC EFFECTS OF A MEGA IMPACT IN THE EARLY ARCHEAN 3470 Ma T.E. Zegers and A. Ocampo European Space Agency, ESTEC, SCI-SB, Keplerlaan 1, 2201 AZ Noordwijk, [email protected] Abstract The oldest impact related layer recognized on Earth occur in greenstone sequences of the Kaapvaal (South Africa) and Pilbara (Australia) Craton, and have been dated at ca. 3470 Ma (Byerly et al., 2002). The simultaneous occurrence of impact layers now geographically widely separated have been taken to indicate that this was a worldwide phenomena, suggesting a very large impact: 10 to 100 times more massive than the Cretaceous-Tertiary event. However, the remarkable lithostratigraphic and chronostratigraphic similarities between the Pilbara and Kaapvaal Craton have been noted previously for the period between 3.5 and 2.7 Ga (Cheney et al., 1988). Paleomagnetic data from two ultramafic complexes in the Pilbara and Kaapvaal Craton showed that at 2.87 Ga the two cratons could have been part of one larger supercontinent called Vaalbara. New Paleomagnetic results from the older greenstone sequences (3.5 to 3.2 Ga) in the Pilbara and Kaapvaal Craton will be presented. The constructed apparent polar wander path for the two cratons shows remarkable similarities and overlap to a large extent. This suggests that the two cratons were joined for a considerable time during the Archean. Therefore, the coeval impact layers in the two cratons at 3.47 Ga do not necessarily suggest a worldwide phenomena on the present scale of separation of the two cratons. -
Open Kosei.Pdf
The Pennsylvania State University The Graduate School Department of Geosciences GEOCHEMISTRY OF ARCHEAN–PALEOPROTEROZOIC BLACK SHALES: THE EARLY EVOLUTION OF THE ATMOSPHERE, OCEANS, AND BIOSPHERE A Thesis in Geosciences by Kosei Yamaguchi Copyright 2002 Kosei Yamaguchi Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy May 2002 We approve the thesis of Kosei Yamaguchi Date of Signature ____________________________________ _______________________ Hiroshi Ohmoto Professor of Geochemistry Thesis Advisor Chair of Committee ____________________________________ _______________________ Michael A. Arthur Professor of Geosciences ____________________________________ _______________________ Lee R. Kump Professor of Geosciences ____________________________________ _______________________ Raymond G. Najjar Associate Professor of Meteorology ____________________________________ _______________________ Peter Deines Professor of Geochemistry Associate Head for Graduate Program and Research in Geosciences iii ABSTRACT When did the Earth's surface environment become oxic? The timing and mechanism of the rise of atmospheric pO2 level in the early Precambrian have been long debated but no consensus has been reached. The oxygenation of the atmosphere and oceans has significant impacts on the evolution of the biosphere and the geochemical cycles of redox-sensitive elements. In order to constrain the evolution of the atmosphere, oceans, biosphere, and geochemical cycles of elements, a systematic and multidisciplinary -
Carbonaceous Cherts of the Barberton Greenstone Belt, South Africa M
Geophysical Research Abstracts, Vol. 8, 04975, 2006 SRef-ID: 1607-7962/gra/EGU06-A-04975 © European Geosciences Union 2006 Carbonaceous cherts of the Barberton Greenstone Belt, South Africa M. van Zuilen (1), M. Chaussidon (2), C. Rollion-Bard (2), B. Luais (2), B Marty (2) (1) Institut de Physique du Globe de Paris, France ([email protected] / Tel: +33 144274833) (2) Centre de Recherche Pétrographiques et Géochimiques, Vandoeuvre les Nancy, France Some of the oldest traces of life on Earth have been found in chert horizons occur- ring in the lower 3.5 Ga Warrawoona Group (eastern Pilbara Craton, Western Aus- tralia), and in the 3.4-3.2 Ga Onverwacht Group (Barberton Greenstone Belt, South Africa). The validity of these claims strongly depends on the geological context, and especially on the process of chert formation. The origin of chert units in the War- rawoona Group has been controversial, since several deposits previously recognized as sedimentary in origin were reinterpreted as hydrothermal feeder dikes. It has been suggested that serpentinization of ocean floor basaltic crust by circulating CO2-rich fluids could have prompted hydrocarbon formation by Fischer-Tropsch (FT-) type re- actions leading to the emplacement of carbonaceous feeder dike cherts. Alternatively, chemolithoautotrophic organisms may actually have been present in such seafloor hy- drothermal systems. These two possibilities highlight the need for detailed geochem- ical studies of the various carbonaceous cherts in Archean greenstone belts in which traces of life have been reported. Here a study is presented of carbonaceous chert de- posits from the Barberton Greenstone Belt (BGB), South Africa. -
Geobiology 2007 Lecture 4 the Antiquity of Life on Earth Homework #2
Geobiology 2007 Lecture 4 The Antiquity of Life on Earth Homework #2 Topics (choose 1): Describe criteria for biogenicity in microscopic fossils. How do the oldest described fossils compare? How has the Brasier-Schopf debate shifted in five years? OR What are stromatolites; where are they found and how are they formed? Articulate the two sides of the debate on antiquity and biogenicity. Up to 4 pages, including figures. Due 3/01/2006 Required readings for this lecture Nisbet E. G. & Sleep N. H. (2001) The habitat and nature of early life, Nature 409, 1083. Schopf J.W. et al., (2002) Laser Raman Imagery of Earth’s earliest fossils. Nature 416, 73. Brasier M.D. et al., (2002) Questioning the evidence for Earth’s oldest fossils. Nature 416, 76. Garcia-Ruiz J.M., Hyde S.T., Carnerup A. M. , Christy v, Van Kranendonk M. J. and Welham N. J. (2003) Self-Assembled Silica-Carbonate Structures and Detection of Ancient Microfossils Science 302, 1194-7. Hofmann, H.J., Grey, K., Hickman, A.H., and Thorpe, R. 1999. Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia. Geological Society of America, Bulletin, v. 111 (8), p. 1256-1262. Allwood et al., (2006) Stromatolite reef from the Early Archaean era of Australia. Nature 441|, 714 J. William Schopf, Fossil evidence of Archaean life (2006) Phil. Trans. R. Soc. B 361, 869–885. Martin Brasier, Nicola McLoughlin, Owen Green and David Wacey (2006) A fresh look at the fossil evidence for early Archaean cellular life. Phil. Trans. R. Soc. B 361, 887–902 What is Life? “Life can be recognized by its deeds — life is disequilibrium, leaving behind the signatures of disequilibrium such as fractionated isotopes or complex molecules. -
Squeezing Blood from a Stone: Inferences Into the Life and Depositional Environments of the Early Archaean
Squeezing Blood From A Stone: Inferences Into The Life and Depositional Environments Of The Early Archaean Jelte Harnmeijer A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington MMX Programs Authorized to Offer Degree: Center for Astrobiology & Early Earth Evolution and Department of Earth & Space Sciences Abstract A limited, fragmentary and altered sedimentary rock record has allowed few constraints to be placed on a possible Early Archaean biosphere, likewise on attendant environmental conditions. This study reports discoveries from three Early Archaean terrains that, taken together, suggest that a diverse biosphere was already well- established by at least ~3.5 Ga, with autotrophic carbon fixation posing the most likely explanation for slightly older 3.7 - 3.8 Ga graphite. Chapter 2 aims to give a brief overview of Early Archaean geology, with special reference to the Pilbara’s Pilgangoora Belt, and biogeochemical cycling, with special reference to banded-iron formation. Chapter 3 reports on the modelled behaviour of abiotic carbon in geological systems, where it is concluded that fractionations incurred through autotrophic biosynthesis are generally out of the reach of equilibrium processes in the crust. In Chapter 4, geological and geochemical arguments are used to identify a mixed provenance for a recently discovered 3.7 - 3.8 Ga graphite-bearing meta-turbidite succession from the Isua Supracrustal Belt in southwest Greenland. In Chapter 5 and 6, similar tools are used to examine a newly discovered 3.52 Ga kerogenous and variably dolomitized magnetite-calcite meta- sediment from the Coonterunah Subgroup at the base of the Pilbara Supergroup in northwest Australia. -
Hydrothermal Alteration at the Panorama Formation, North Pole Dome, Pilbara Craton, Western Australia
Hydrothermal Alteration at the Panorama Formation, North Pole Dome, Pilbara Craton, Western Australia Adrian J. Brown*1, Thomas J. Cudahy,2,3 and Malcolm R. Walter3 1 SETI Institute, 515 N. Whisman Rd, Mountain View, CA 94043, USA 2 CSIRO Exploration and Mining, ARRC Centre, Kensington, WA 6102, Australia 3Australian Centre For Astrobiology, Macquarie University, NSW 2109, Australia ABSTRACT An airborne hyperspectral remote sensing dataset was obtained of the North Pole Dome region of the Pilbara Craton in October 2002. It has been analyzed for indications of hydrothermal minerals. Here we report on the identification and mapping of hydrothermal minerals in the 3.459 Ga Panorama Formation and surrounding strata. The spatial distribution of a pattern of subvertical pyrophyllite rich veins connected to a pyrophyllite rich palaeohorizontal layer is interpreted to represent the base of an acid-sulfate epithermal system that is unconformably overlain by the stromatolitic 3.42Ga Strelley Pool Chert. KEYWORDS Pilbara, North Pole Dome, Panorama Formation, pyrophyllite, hydrothermal, hyperspectral, stromatolites, Strelley Pool Chert * corresponding author, email: [email protected] ~ 1 ~ Hydrothermal Alteration at the Panorama Formation, Pilbara Craton INTRODUCTION yperspectral remote sensing has been used in the past to successfully Hsurvey Archean regions of Western Australia (Cudahy, et al., 2000). As part of a combined Australian Centre for Astrobiology-CSIRO project to map the North Pole Dome in the Pilbara region, a remote sensing dataset was collected in October 2002 and has been analyzed in the years hence. The dataset was obtained using the reflectance spectrometer called HyMap (Cocks, et al., 1998), owned and operated by HyVista Corporation. -
Geological Archive of the Onset of Plate Tectonics
View metadata, citation and similar papers at core.ac.uk brought to you by CORE Geological archive of the onsetprovided by espace@Curtin of plate tectonics rsta.royalsocietypublishing.org Peter A. Cawood1,2, Chris J. Hawkesworth2,3, Sergei A. Pisarevsky4, Bruno Dhuime3,5, 1 1 Research Fabio A. Capitanio andOliverNebel 1 Cite this article: Cawood PA, Hawkesworth School of Earth, Atmosphere and Environment, Monash University, CJ, Pisarevsky SA, Dhuime B, Capitanio FA, Melbourne, VIC 3800, Australia 2 Nebel O. 2018 Geological archive of the onset Department of Earth Sciences, University of St Andrews, of plate tectonics. Phil.Trans.R.Soc.A376: St Andrews, Fife KY16 9AL, UK 20170405. 3School of Earth Sciences, University of Bristol, Wills Memorial http://dx.doi.org/10.1098/rsta.2017.0405 Building, Queens Road, Bristol BS8 1RJ, UK 4ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and Accepted:21June2018 Earth Dynamics Research Group, The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin One contribution of 14 to a discussion meeting University, GPO Box U1987, Perth, WA 6845, Australia issue‘Earthdynamicsandthedevelopmentof 5CNRS-UMR 5243, Géosciences Montpellier, Université de plate tectonics’. Montpellier, Montpellier, France Subject Areas: PAC, 0000-0003-1200-3826;BD,0000-0002-4146-4739; plate tectonics, geochemistry, geology ON, 0000-0002-5068-7117 Keywords: Plate tectonics, involving a globally linked system of lateral motion of rigid surface plates, is a plate tectonics, Archaean, palaeomagnetics, characteristic feature of our planet, but estimates lithosphere, early Earth of how long it has been the modus operandi of lithospheric formation and interactions range from Author for correspondence: the Hadean to the Neoproterozoic. -
The Mesoarchaean Mosquito Creek Basin of the East Pilbara, Western Australia
Precambrian Research 180 (2010) 251–271 Contents lists available at ScienceDirect Precambrian Research journal homepage: www.elsevier.com/locate/precamres The waning stage of a greenstone belt: The Mesoarchaean Mosquito Creek Basin of the East Pilbara, Western Australia Wouter Nijman ∗, Quintijn Clevis 1, Sjoukje T. de Vries 2 Department of Sedimentology, Faculty of Geosciences, Utrecht University, Postbus 80021, 3508 TA Utrecht, The Netherlands article info abstract Article history: The Mosquito Creek Basin stands apart in the Archaean granite–greenstone terrane of the east Pilbara Received 16 October 2009 Craton because of the rectangular outcrop but crescent-shaped subcrop, and its composition of low- Received in revised form 25 February 2010 grade metamorphic mainly turbiditic clastic sedimentary rocks. These sediments belong to the c. 2.9 Ga Accepted 9 March 2010 Mosquito Creek Formation. Tectonic interpretations of the basin have varied from a simple synclinorium, to an accretionary prism, an extensional passive margin, and more recently into a rift basin separating the Kurrana Terrane from the East Pilbara Terrane (EPT). Keywords: Combined sedimentological and structural–geological investigations show coarse-clastic fan-delta Mesoarchaean Pilbara Craton marginal facies with stacked unconformities, rimming an E–W basin centre with predominantly finer- Mosquito Creek Basin grained mass flow-dominated sediments. A N–S traverse therefore contains a complete cross-section of Archaean sedimentary basins the Mosquito Creek Basin, shortened to about 50% of its original width by tight folding and thrusting. Greenstone belt evolution The basin fill shows one major FU sequence from fan-delta sandstone to distal turbidites, unconformably overlying an older, partially preserved clastic sequence of comparable facies. -
Tectonic Evolution of the Early Archaean Doolena Gap Greenstone Belt, East Pilbara Terrane, Western Australia
TECTONIC EVOLUTION OF THE EARLY ARCHAEAN DOOLENA GAP GREENSTONE BELT, EAST PILBARA TERRANE, WESTERN AUSTRALIA by Daniel Wiemer (Dipl. Geol./M.Sc.) ____________________________________________ Submitted in total fulfillment of the requirements for the degree of Doctor of Philosophy (Ph.D.) Brisbane, 2017 School of Earth, Environmental and Biological Sciences Science and Engineering Faculty Queensland University of Technology Supervisor: Dr. David T. Murphy Co-supervisor: Dr. Christoph E. Schrank ii QUT Verified Signature iii Abstract Earth’s oldest preserved crust is characterised by a distinctive crustal architecture of large ovoid granitic domes surrounded by curvilinear supracrustal greenstone belts. Such dome-and-keel morphology is not generated in the present-day Earth as part of plate tectonics. This indicates that the crustal fragments preserved from the early Earth, which had higher heat generation and therefore higher temperatures, formed in a distinct non-plate tectonic style tectono-magmatic regime. Here I investigate the lithological associations, the magmatic contributions and the structural kinematics that gave rise to the distinctive Archean dome and keel morphology. In doing so I test the model of partial convective overturn for the formation of the dome-and-keel crustal architecture in which dense mafic crust overlying lower density felsic crust leads to buoyancy instabilities and crustal-scale reorganization. The 3530- 3225 Ma East Pilbara Terrane, Western Australia, contains the best preserved lithological and structural inventory associated with dome-and-keel formation, making it the archetypical early Archean dome-and-keel terrane and the perfect natural laboratory for investigating early Archaean tectonic processes. Here I present a detailed lithostratigraphic, structural, petrological, geochemical, and geochronological study of a well exposed geological transect through the dome-and-keel terrane of the transition between the western Doolena Gap greenstone belt and the Muccan Granitic Complex. -
Stromatolites: Biogenicity, Biosignatures, and Bioconfusion
Invited Paper Stromatolites: Biogenicity, Biosignatures, and Bioconfusion Stanley M. Awramikl*a d Kathleen Greyb a Departmentof Geological Sciences, Preston Cloud Research Laboratory, University of California, Santa Barbara, CA 93 1 06, USA b Geological Survey of Western Australia, Department of Industry and Resources, 100 Plain Street, East Perth, WA 6004, Australia ABSTRACT Stromatolites represent a multifarious system ofnested, physically, chemically, and biologically influenced components that range in scale from microscopic to macroscopic. These components can include microorganisms, organic compounds of microorganisms, sediment grains, precipitated sediment, sedimentary textures (fabrics), microstructure, laminae, domes, columns, branched columns, and cones. Millimeter to meter scale edifices (stromatolites) are the result. Stromatolites once played a significant role in establishing life's presence on the early Earth, but now a shift away from reliance on stromatolites is occurring. There is a perception that Archean stromatolite-like structures have low reliability to signal life. This is likely due to (1) no unified theory on stromatolite morphogenesis, (2) no valid or appropriate modern analog to use in the interpretation ofArchean stromatolites, and (3) disagreement on how to defme the word stromatolite. No single feature or line ofevidence has yet been found that can unequivocally indicate a biogenic nature for a stromatolite. However, a range of features and their combinations that are well documented for the vast majority offossil stromatolites and are found in some living stromatolites, are difficult, ifnot impossible, to account for by inorganic processes. Morphology remains a valid criterion to indicate biogenicity. Keywords: stromatolites, biogenicity, abiogenic, Archean 1. INTRODUCTION As the sedimentary layers of Earth's history are peeled away and Archean rocks (older than >2.5 Ga) are exposed, the record of sedimentary rocks becomes sparse and the evidence for life becomes meager and difficult to read.