DOCSLIB.ORG

Reassessing the Biogenicity of Earthts Oldest Trace Fossil With

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Reassessing the Biogenicity of Earthts Oldest Trace Fossil With Reassessing the biogenicity of Earth’s oldest trace fossil with implications for biosignatures in the search for early life Eugene G. Grosch1 and Nicola McLoughlin Department of Earth Science and Centre for Geobiology, University of Bergen, N-5007 Bergen, Norway Edited* by Norman H. Sleep, Stanford University, Stanford, CA, and approved April 28, 2014 (received for review February 10, 2014) Microtextures in metavolcanic pillow lavas from the Barberton argued biogenic origin from pillow lavas of the in situ oceanic greenstone belt of South Africa have been argued to represent crust and ophiolites (1, 2, 9). In young, in situ pillow lavas, Earth’s oldest trace fossil, preserving evidence for microbial life abundant microbial DNA and geochemical signatures support in the Paleoarchean subseafloor. In this study we present new in the presence of a deep subseafloor biosphere (10, 11). Given situ U–Pb age, metamorphic, and morphological data on these therefore the major implications that the Archean titanite titanite microtextures from fresh drill cores intercepting the type microtextures may hold for the earliest evidence of life on Earth, locality. A filamentous microtexture representing a candidate bio- we have conducted syngenicity and biogenicity tests to evaluate signature yields a U–Pb titanite age of 2.819 ± 0.2 Ga. In the same a proposed subseafloor bioalteration model for their origin. We drill core hornfelsic-textured titanite discovered adjacent to a local report in situ U–Pb dating of the titanite, quantitative microscale mafic sill records an indistinguishable U–Pb age of 2.913 ± 0.31 Ga, mapping of metamorphic conditions, and morphological evi- overlapping with the estimated age of intrusion. Quantitative mi- dence to evaluate the biogenicity of the titanite microtextures. croscale compositional mapping, combined with chlorite thermo- dynamic modeling, reveals that the titanite filaments are best Results developed in relatively low-temperature microdomains of the The titanite microtextures were originally described from pillow chlorite matrix. We find that the microtextures exhibit a morpho- lavas of the ca. 3.472-Ga Hooggenoeg Formation of the BGB logical continuum that bears no similarity to candidate biotextures ca. EARTH, ATMOSPHERIC, that stratigraphically overlies 3.482 Ga ultramafic komatiites AND PLANETARY SCIENCES found in the modern oceanic crust. These new findings indicate of the Komati Formation (Fig. S1). The current study includes that the titanite formed during late Archean ca. 2.9 Ga thermal samples from drill core KD2b of the Barberton Scientific Dril- contact metamorphism and not in an early ca. 3.45 Ga subseafloor ling Project (BSDP) that intercepted the pillow lava type section environment. We therefore question the syngenicity and biogenic- for the proposed biotextures (12, 13) (Fig. S1). Petrographic ity of these purported trace fossils. It is argued herein that the investigation of the drill core samples reveals that the original titanite microtextures are more likely abiotic porphyroblasts of titanite bioalteration textures (1) form part of a morphological thermal contact metamorphic origin that record late-stage retro- continuum that was previously only partially illustrated. The size, grade cooling in the pillow lava country rock. A full characteriza- morphology, and distribution of these titanite microtextures are tion of low-temperature metamorphic events and alternative evaluated against biogenicity criteria proposed for endolithic biosignatures in greenstone belt pillow lavas is thus required microborings (14, 15). The simplest morphological endmember before candidate traces of life can be confirmed in Archean is hornfelsic titanite spheres (Fig. 1 A–E) that may coalesce to subseafloor environments. form irregular bands. The spheres and bands develop filamentous Archean habitats | astrobiology | Archean Earth | ichnofossil | bioalteration Significance ilamentous titanite microtextures in ca. 3.472–3.432 Ga It has been argued that Archean subseafloor pillow lava Fmetavolcanic pillow lavas of the Barberton greenstone belt sequences provide an environment in which to seek evidence (BGB), South Africa, have been argued to represent Earth’s for the earliest traces of life. Candidate titanite biosignatures oldest trace fossils (1–4). Subsequent work in other Archean of microbial activity have been reported in ∼3.45-Ga meta- terrains, such as the Pilbara Craton of Western Australia and the volcanic glass from the Barberton greenstone belt of South Abitibi greenstone belt of Canada, have made similar claims for Africa. In this paper we present new in situ U–Pb age data, trace fossils in early metabasaltic pillow lavas (5, 6). The current metamorphic constraints, and morphological observations on paradigm for these titanite microtextures involves a complex these titanite microtextures. Our data challenges a biological bioalteration model in which endolithic microbes form hollow origin for these oldest purported trace fossils, with implications microtunnels by etching fresh volcanic glass in submarine envi- for the ecological niches where life may have first emerged. We ronments on the early Earth (1–7). Subseafloor hydrothermal therefore suggest alternative biosignatures and approaches alteration is envisioned not only to provide a suitable environ- should be considered in the search for subsurface life on early – ment for microbial activity, but also to result in mineralization of Earth and in extraterrestrial mafic ultramafic rocks, for exam- ple, in martian basalts. the hollow tubes by titanite (CaTiSiO5) preserving the proposed trace fossils (1–3). Thus, it has been suggested that volcanic Author contributions: E.G.G. designed research; E.G.G. and N.M. performed research; E.G.G. habitats represent a previously unexplored geological setting in and N.M. contributed new reagents/analytic tools; E.G.G. and N.M. analyzed data; and which life may have thrived and possibly originated on the early E.G.G. wrote the paper. Earth (1–3). It has also been argued that similar microtextures in The authors declare no conflict of interest. altered extraterrestrial basalts may provide a useful biosignature *This Direct Submission article had a prearranged editor. in the search for life on Mars and beyond (8). Freely available online through the PNAS open access option. The principal argument for a biogenic origin of the purported 1To whom correspondence should be addressed. E-mail: [email protected]. Archean trace fossils is based on their apparent similarity in size, This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. shape, and distribution to partially mineralized microtubules of 1073/pnas.1402565111/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1402565111 PNAS Early Edition | 1of6 Downloaded by guest on September 26, 2021 Fig. 1. Titanite microtextures in Archean metavolcanic pillow lavas now comprising a chlorite dominated matrix, compared with partially mineralized microtunnels from younger oceanic crust. (A–F) A continuum of titanite microtextures from spheres with or without filamentous projections, to well- developed clusters with radiating filaments, LA tracks for U–Pb titanite dating are shown (white bands in C). (G) Partially mineralized microtubules radiating at high angles from a fracture in volcanic glass from Ocean Drilling Program hole 418A in the West Atlantic. (H) Curvilinear and spiral-shaped (Inset) microtunnels in volcanic glass of the Troodos ophiolite Cyprus (drill core CY-1A). (I) Histogram of measured Archean titanite filament widths (n = 303) in 12 samples from the Barberton drill core showing that they are much larger in diameter (dark green line = mean of 12 μm and light green band = SD) and span a wider range compared with microtubules in younger volcanic glass (dark purple line = mean of 1.3 μm and light purple band = SD, replotted from ref. 2). (Scale bars: 50 μm A–H except G and H, Insets, which are 10 μm.) projections (Fig. 1 A, C, and D), showing a growth continuum indicate no morphological similarity between the Archean from spheres with one or two short projections to larger clusters titanite microtextures and the modern tubular bioalteration of titanite microtextures with more numerous and longer pro- textures. jections (Fig. 1 B and D–F; Fig. S2). The latter morphotype with As a syngenicity test, the U–Pb age of titanite growth was well-developed titanite filaments has been the focus of all pre- determined by in situ measurements using single- and multi- vious studies but forms only a less abundant endmember of collector laser ablation, inductively coupled plasma mass spec- the morphological continuum. The individual filaments are trometry (LA-ICP-MS). Further details on the methods and highly variable in length (e.g., Fig. 1F, from 14 to 460 μm) and SI Materials and Methods μ analytical standards are presented in . width (from 2 to 39 m) and are either constant in diameter, The 207Pb/206Pb and 238U/206Pb isotopic ratios measured by tapered (Fig. 1E), or club shaped (Fig. 1G). The filaments do not single-collector LA-ICP-MS on spherical hornfelsic titanite uniquely radiate at high angles from titanite “root zones” as in (sample B77) are plotted on a Tera–Wasserburg Concordia modern oceanic basalts (Fig. 1 G and H), but rather at varying diagram (Fig. 2; Tables S1 and S2). The measured U–Pb and angles from irregular titanite bands and spheres disseminated – throughout the chlorite matrix (Fig. 1 E and F). The new drill Pb
Load more

Recommended publications
  • Volcanology and Mineral Deposits
    THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use. Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”).
    [Show full text]
  • Geochemical Heterogeneity Within Mid-Ocean Ridge Lava £Ows: Insights Into Eruption, Emplacement and Global Variations in Magma Generation
    Earth and Planetary Science Letters 188 (2001) 349^367 www.elsevier.com/locate/epsl Geochemical heterogeneity within mid-ocean ridge lava £ows: insights into eruption, emplacement and global variations in magma generation K.H. Rubin a;*, M.C. Smith a, E.C. Bergmanis a, M.R. Per¢t b, J.M. Sinton a, R. Batiza a;c a b c Received 5 September 2000; accepted 28 March 2001 Abstract Compositional heterogeneity in mid-ocean ridge (MOR) lava flows is a powerful yet presently under-utilized volcanological and petrological tracer. Here, it is demonstrated that variations in pre- and syn-eruptive magmatic conditions throughout the global ridge system can be constrained with intra-flow compositional heterogeneity among 10 discrete MOR flows. Geographical distribution of chemical heterogeneity within flows is also used along with mapped physical features to help decipher the range of conditions that apply to seafloor eruptions (i.e. inferred vent locations and whether there were single or multiple eruptive episodes). Although low-pressure equilibrium fractional crystallization can account for much of the observed intra-flow compositional heterogeneity, some cases require multiple parent magmas and/or more complex crystallization conditions. Globally, the extent of within-flow compositional heterogeneity is well correlated (positively) with estimated erupted volume for flows from the northern East Pacific Rise (EPR), and the Mid Atlantic, Juan de Fuca and Gorda Ridges; however, some lavas from the superfast spreading southern EPR fall below this trend. Compositional heterogeneity is also inversely correlated with spreading rate. The more homogeneous compositions of lavas from faster spreading ridges likely reflect the relative thermal stability and longevity of sub-ridge crustal magma bodies, and possibly higher eruption frequencies.
    [Show full text]
  • Subglacial and Submarine Volcanism in Iceland
    Mars Polar Science 2000 4078.pdf SUBGLACIAL AND SUBMARINE VOLCANISM IN ICELAND. S. P. Jakobsson, Icelandic Inst. of Natural His- tory, P. O. Box 5320, 125 Reykjavik, Iceland Introduction: Iceland is the largest landmass ex- mounds, ridges and tuyas [5]. The thickness of basal posed along the Mid-Ocean Ridge System. It has been basaltic pillow lava piles often exceeds 60-80 meters constructed over the past 16 Ma by basaltic to silicic and a 300 m thick section has been reported. Pillow volcanic activity occurring at the Mid-Atlantic Ridge, lavas may also form lenses or pods at a higher level in and is topographically elevated because of the abundant the volcanoes. igneous material produced in association with the Ice- It has been suggested that at a water depth less than land hot spot, the center of which is thought to be lo- approximately 100-150 m, basaltic phreatic explosions cated beneath Vatnajokull glacier [1]. The axial rift produce hydroclastites. It appears feasible to subdivide zones which run through Iceland from southwest to the hyaloclastites of the Icelandic ridges and tuyas, ge- northeast are in direct continuation of the crestal zones netically into two main types. A substantial part of the of the Mid Atlantic Ridge and are among the most ac- base of the submarine Surtsey tuya is poorly bedded, tive volcanic zones on Earth. unsorted, hydroclastite, which probably was quenched Subglacial Volcanism: Volcanic accumulations of and rapidly accumulated below the seawater level with- hyaloclastites which are deposits formed by the intru- out penetrating the surface [6]. Only 1-2 % of the vol- sion of lava beneath water or ice and the consequent ume of extruded material in the 1996 Gjalp eruption fell shattering into small angular vitric particles, combined as air-fall tephra, the bulk piled up below the ice [4].
    [Show full text]
  • High-Silica Lava Morphology at Ocean Spreading Ridges: Machine-Learning Seafloor Classification at Alarcon Rise
    Article High-Silica Lava Morphology at Ocean Spreading Ridges: Machine-Learning Seafloor Classification at Alarcon Rise Christina H. Maschmeyer 1,†, Scott M. White 1,*, Brian M. Dreyer 2 and David A. Clague 3 1 School of the Earth, Ocean and Environment, University of South Carolina, Columbia, SC 29208, USA; [email protected] 2 Institute of Marine Sciences, University of California, Santa Cruz, CA 95064, USA; [email protected] 3 Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA; [email protected] † Now at: Fugro USA Marine, Inc. Geoconsulting Exploration, 6100 Hillcroft Ave, Houston, TX 77081, USA * Correspondence: [email protected] Received 31 March 2019; Accepted 28 May 2019; Published: 1 June 2019 Abstract: The oceanic crust consists mostly of basalt, but more evolved compositions may be far more common than previously thought. To aid in distinguishing rhyolite from basaltic lava and help guide sampling and understand spatial distribution, we constructed a classifier using neural networks and fuzzy inference to recognize rhyolite from its lava morphology in sonar data. The Alarcon Rise is ideal to study the relationship between lava flow morphology and composition, because it exhibits a full range of lava compositions in a well‐mapped ocean ridge segment. This study shows that the most dramatic geomorphic threshold in submarine lava separates rhyolitic lava from lower‐silica compositions. Extremely viscous rhyolite erupts as jagged lobes and lava branches in submarine environments. An automated classification of sonar data is a useful first‐order tool to differentiate submarine rhyolite flows from widespread basalts, yielding insights into eruption, emplacement, and architecture of the ocean crust.
    [Show full text]
  • 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
    [Show full text]
  • Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains
    Progress Reports Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains by Eugene G. Grosch, Nicola McLoughlin, Maarten de Wit, and Harald Furnes doi:10.2204/iodp.sd.8.03.2009 Introduction phase of drilling yielded three boreholes with a total of 800 m of core with 99% core recovery in the early Archean Barberton In the Barberton Scientific Drilling Program (BSDP) we Greenstone Belt (BGB), South Africa. Five decades of scien- successfully completed three drill holes in 2008 across tific research on the 3.5–3.1-Ba-old BGB has established the strategically selected rock formations in the early Archean mountain ranges of Barberton as a world heritage site and a Barberton Greenstone Belt, South Africa. This collaborative focus for international scientists interested in early Earth project’s goal is to advance understanding of geodynamic processes. The rocks around Barberton are unique in that and biogeochemical processes of the young Earth. The they represent relatively intact and undisturbed remnants of program aims to better define and characterize Earth’s preserved ancient seafloor and continental crust that have earliest preserved ocean crust shear zones and microbial largely escaped tectonometamorphic reworking since the borings in Archean basaltic glass, and to identify biogeo- time they formed (Schoene et al., 2008). chemical fingerprints of ancient ecological niches recorded in rocks. The state-of-the-art analytical and imaging work Outstanding questions about early Earth—as well as will address the question of earliest plate tectonics in the Earth systems and linkages between physical, chemical, and Archean, the δ18O composition, the redox state and biological processes operating within and on the early temperature of Archean seawater, and the origin of life Earth—include the following areas of interest: question.
    [Show full text]
  • Glaciovolcanic Megapillows of Undirhlíđar, Reykjanes Peninsula, Southwestern Iceland
    GLACIOVOLCANIC MEGAPILLOWS OF UNDIRHLÍĐAR, REYKJANES PENINSULA, SOUTHWESTERN ICELAND Rachel Heineman Honors Research in Geology Dr. F. Zeb Page, Thesis Advisor Oberlin College 2016-2017 ABSTRACT At Undirhlíðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring throughout this area demonstrate their role in the multi-stage construction of the ridge modeled by Pollock et al. (2014). The outcrops exhibit radial jointing, bands of vesicles and glassy rims; they occur in high relief surrounded by basalt breccia resembling pillow rubble, and are composed of plagioclase-phyric olivine basalt with plagioclase-rich groundmass. They occur in multiple pillow lava units formed from two distinct magma batches. Two groups of outcrops are represented that are petrographically, geochemically and geographically distinct; the first group is near to and consistent with the pillow units of Undirhlíðar quarry described by Pollock et al. (2014), and the second group, located near the tephra cone, is derived from a more evolved unit of the same magma. Megapillows show significant plagioclase accumulation with variable phenocryst zoning, indicating the movement of multiple pulses of magma through the megapillows. Megapillows at Undirhlíðar may represent a significant mechanism, demonstrated elsewhere at a marine ​ megapillow by Goto and McPhie (2004), for magmatic distribution: feeding and then overrunning pillows which propagate and are fed from their basal margins at the eruptive front. INTRODUCTION Pillow lavas are among the most common lava morphologies on Earth, yet the construction of pillow-dominated volcanoes is not widely understood due to the relative inaccessibility of the submarine environments in which they form.
    [Show full text]
  • Explanatory Notes for the Time–Space Diagram and Stratotectonic Elements Map of Tasmania
    Tasmanian Geological Survey TASMANIA DEVELOPMENT Record 1995/01 AND RESOURCES Tasgo NGMA Project Sub-Project 1: Geological Synthesis Explanatory notes for the Time–Space Diagram and Stratotectonic Elements Map of Tasmania by D. B. Seymour and C. R. Calver Tasmanian Geological Survey Record 1995/01 1 CONTENTS INTRODUCTION ..................................................................................................................... 4 KING ISLAND.......................................................................................................................... 5 ?Mesoproterozoic ............................................................................................................... 5 Neoproterozoic orogenesis and granitoid intrusive rocks ................................................ 5 ?Neoproterozoic sequences ................................................................................................ 5 Early Carboniferous granitoid intrusive rocks ................................................................ 6 ROCKY CAPE ELEMENT....................................................................................................... 7 ?Mesoproterozoic: Rocky Cape Group ............................................................................... 7 Burnie and Oonah Formations ........................................................................................ 7 Smithton Synclinorium .................................................................................................... 7 Ahrberg Group .................................................................................................................
    [Show full text]
  • Solidification and Morphology of Submarine Lavas: a Dependence on Extrusion Rate
    Portland State University PDXScholar Geology Faculty Publications and Presentations Geology 12-10-1992 Solidification and Morphology of Submarine Lavas: A Dependence on Extrusion Rate Ross W. Griffiths Australia National University Jonathan H. Fink Portland State University, [email protected] Follow this and additional works at: https://pdxscholar.library.pdx.edu/geology_fac Part of the Geology Commons, and the Volcanology Commons Let us know how access to this document benefits ou.y Citation Details Griffiths, R.., W & Fink, J. H. (1992). Solidification and morphology of submarine lavas: A dependence on extrusion rate. Journal of Geophysical Research: Solid Earth (1978–2012), 97(B13), 19729-19737. This Article is brought to you for free and open access. It has been accepted for inclusion in Geology Faculty Publications and Presentations by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 97, NO. BI3, PAGES 19,729-19,737, DECEMBER 10 , 1992 Solidification and Morphology of Submarine Lavas: A Dependence on Extrusion Rate Ross W. GRIFFITIIS Research Sclwol of Earth Sciences, Australian National University, Canberra JONATIIAN H. FINK Geology Department, Arizona State University, Tempe The results of recent laboratory experiments with wax extruded beneath relatively cold water may be . extr~polated to predict the surface morphology of submarine lavas as a function of the extrusion rate and melt vIscosity. ~e experiments with solidifying wax indicated that the surface morphology was controlled bya slDgle paramete~ , the raUo of the time taken for the surface to solidify, and a time scale for lateral flow.
    [Show full text]
  • The Rouyn-Pelletier Caldera Complex of the Blake River Group, Abitibi Greenstone Belt, Canada
    Canadian Journal of Earth Sciences Reconstruction and evolution of Archean intracaldera facies: the Rouyn-Pelletier Caldera Complex of the Blake River Group, Abitibi greenstone belt, Canada Journal: Canadian Journal of Earth Sciences Manuscript ID cjes-2015-0029.R2 Manuscript Type: Article Date Submitted by the Author: 03-Jan-2016 Complete List of Authors: Moore, Lyndsay N.; Université du Québec à Chicoutimi, Dépt. Sciences de la Terre Draft Daigneault, Réal; Université du Québec à Chicoutimi, Dépt. Sciences de la Terre Aird, Hannah M.; California State University Chico, Geological and Environmental Sciences Department Banerjee, Neil R.; Western University, Department of Earth Sciences Mueller, Wulf U.; Module des Sciences de la Terre Keyword: Archean, subaqueous, caldera, volcanic architecture, facies https://mc06.manuscriptcentral.com/cjes-pubs Page 1 of 70 Canadian Journal of Earth Sciences Reconstruction and evolution of Archean intracaldera facies: the Rouyn-Pelletier Caldera Complex of the Blake River Group, Abitibi greenstone belt, Canada Moore, L.N. a, Daigneault, R. a, Aird, H.M. b, Banerjee, N.R. c and Mueller, W.U. a,1 a Centre d’études sur les ressources minérales (CERM), Université du Québec à Chicoutimi (UQAC) 555 boul. de l’Université, Chicoutimi, Québec, Canada, G7H 2B1 b Geological and Environmental Sciences Department (GEOS), California State University - Chico, Chico, California, 95929 c Department of Earth Sciences, Western University, London, Ontario, N6A 5B7 1 Deceased on May 16 th , 2010 Draft Corresponding Author: [email protected] Telephone: 1-418-545-5011 Fax: 1-418-545-5012 Present Address: Université du Québec à Chicoutimi, 555 boul. de l’Université, Chicoutimi, Québec, Canada, G7H 2B1 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 2 of 70 1 Abstract 2 Sub-vertically- to vertically-dipping Archean strata provide an excellent opportunity to study 3 synvolcanic structures and internal organization of subaqueous volcanic complexes.
    [Show full text]
  • NE Temagami Area, Table
    THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use. Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”).
    [Show full text]
  • New Approach to Uranium-Gold Systems
    oreNewsletter of CODES, the ARC Centresolutions of Excellence in Ore Deposits at the University of Tasmania Winter 2009 / No. 25 New approach to uranium-gold systems team led by Dr David The project builds upon expertise in in these deposits, and the conditions under Selley from CODES, and sediment-hosted base-metal ores (Cu- which they attain ore grade concentrations. Co and Pb-Zn) that has been developed Consideration of these polymetallic Prof. Murray Hitzman A through two decades of research on some deposits as a spectrum between end- from the Colorado School of of the world’s most richly endowed basins, continued page 2 » Mines (CSM) node, is proposing including McArthur Basin in northern a research project to develop Australia and the Katangan Basin in central Temple Mountain, Utah – one of the sites Africa. The project also includes intellectual selected for deposit case studies. The mountain and test a holistic exploration is famous for its polymetallic urano-organic ores, capital developed through recent model for the formation and which include fracture-controlled varieties within research of world-class sediment-hosted and at the margins of a transgressive collapse location of polymetallic U-Au- Au provinces - in particular, concepts of breccia, and greater stratabound concentrations PGM-Ni-REE-Mo-Co ores. organically-mediated metal concentration. within sandstones of the Moss Back Member. Bleaching within the collapse (reduction of iron) In developing the models, emphasis will and abundant petroliferous organic matter within be placed on understanding the significance peripheral sandstones record infiltration of mobile of precious metal and base metal enrichment hydrocarbons.
    [Show full text]