State Party Response to the Supplimentary Information Requested by Iucn for the Barberton Makhonjwa Mountains World Heritage
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Geology of the Eoarchean, >3.95 Ga, Nulliak Supracrustal
ÔØ ÅÒÙ×Ö ÔØ Geology of the Eoarchean, > 3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics Tsuyoshi Komiya, Shinji Yamamoto, Shogo Aoki, Yusuke Sawaki, Akira Ishikawa, Takayuki Tashiro, Keiko Koshida, Masanori Shimojo, Kazumasa Aoki, Kenneth D. Collerson PII: S0040-1951(15)00269-3 DOI: doi: 10.1016/j.tecto.2015.05.003 Reference: TECTO 126618 To appear in: Tectonophysics Received date: 30 December 2014 Revised date: 30 April 2015 Accepted date: 17 May 2015 Please cite this article as: Komiya, Tsuyoshi, Yamamoto, Shinji, Aoki, Shogo, Sawaki, Yusuke, Ishikawa, Akira, Tashiro, Takayuki, Koshida, Keiko, Shimojo, Masanori, Aoki, Kazumasa, Collerson, Kenneth D., Geology of the Eoarchean, > 3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics, Tectonophysics (2015), doi: 10.1016/j.tecto.2015.05.003 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT Geology of the Eoarchean, >3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics Tsuyoshi Komiya1*, Shinji Yamamoto1, Shogo Aoki1, Yusuke Sawaki2, Akira Ishikawa1, Takayuki Tashiro1, Keiko Koshida1, Masanori Shimojo1, Kazumasa Aoki1 and Kenneth D. -
Implications for Global-Scale Plate Tectonics Hamed Gamal El Dien1,2 ✉ , Luc S
www.nature.com/scientificreports OPEN Geochemical evidence for a widespread mantle re-enrichment 3.2 billion years ago: implications for global-scale plate tectonics Hamed Gamal El Dien1,2 ✉ , Luc S. Doucet1, J. Brendan Murphy1,3 & Zheng-Xiang Li1 Progressive mantle melting during the Earth’s earliest evolution led to the formation of a depleted mantle and a continental crust enriched in highly incompatible elements. Re-enrichment of Earth’s mantle can occur when continental crustal materials begin to founder into the mantle by either subduction or, to a lesser degree, by delamination processes, profoundly afecting the mantle’s trace element and volatile compositions. Deciphering when mantle re-enrichment/refertilization became a global-scale process would reveal the onset of efcient mass transfer of crust to the mantle and potentially when plate tectonic processes became operative on a global-scale. Here we document the onset of mantle re-enrichment/refertilization by comparing the abundances of petrogenetically signifcant isotopic values and key ratios of highly incompatible elements compared to lithophile elements in Archean to Early-Proterozoic mantle-derived melts (i.e., basalts and komatiites). Basalts and komatiites both record a rapid-change in mantle chemistry around 3.2 billion years ago (Ga) signifying a fundamental change in Earth geodynamics. This rapid-change is recorded in Nd isotopes and in key trace element ratios that refect a fundamental shift in the balance between fuid-mobile and incompatible elements (i.e., Ba/La, Ba/Nb, U/Nb, Pb/Nd and Pb/Ce) in basaltic and komatiitic rocks. These geochemical proxies display a signifcant increase in magnitude and variability after ~3.2 Ga. -
Petrogenesis of 3.15 Ga Old Banasandra Komatiites from the Dharwar Craton, India: Implications for Early Mantle Heterogeneity
Accepted Manuscript Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar craton, India: Implications for early mantle heterogeneity J.M. Maya, Rajneesh Bhutani, S. Balakrishnan, S. Rajee Sandhya PII: S1674-9871(16)30025-1 DOI: 10.1016/j.gsf.2016.03.007 Reference: GSF 443 To appear in: Geoscience Frontiers Received Date: 5 November 2015 Revised Date: 1 March 2016 Accepted Date: 3 March 2016 Please cite this article as: Maya, J.M., Bhutani, R., Balakrishnan, S., Sandhya, S.R., Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar craton, India: Implications for early mantle heterogeneity, Geoscience Frontiers (2016), doi: 10.1016/j.gsf.2016.03.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT MANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT 1 Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar 2 craton, India: Implications for early mantle heterogeneity * 3 J. M. Maya, Rajneesh Bhutani , S. Balakrishnan, S. Rajee Sandhya 4 Department of Earth Sciences, Pondicherry University, Puducherry-605014, India 5 6 *Corresponding author. Phone: +919443636422; 7 E-mail address: [email protected] 8 9 MANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT 10 Abstract 11 Spinifex-textured, magnesian (MgO >25 wt.%) komatiites from Mesoarchean 12 Banasandra greenstone belt of the Sargur Group in the Dharwar craton, India were 13 analysed for major and trace elements and 147,146 Sm-143,142 Nd systematics to constrain 14 age, petrogenesis and to understand the evolution of Archean mantle. -
AST 201 - Introduction to Astrobiology Script
AST 201 - Introduction to Astrobiology Script Samuel Gunz1 and Martin Emons1 1Department of Biosystems Science and Engineering, ETH Zurich Autumn 2020 1 What is Life? Note that also some non-living things satisfy some of these traits (e.g. Fire, snowflake). In addition, some living things The definition of Life is not simple. NASA defines life as (e.g. seed, bacteria) can undergo a period of dormancy. Are follows, “Life is a self-sustaining system capable of Dar- they dead during that time because they are not growing, winian evolution.”. However, this excludes for instance metabolising or interacting with the environment? mules as they are infertile. The definition might depend in which context it is asked. Different smart people came up with various definitions, however they could never agree 1.2 Physical definition of life upon a single definition. It is important that a definition Life is an ordered system of molecules that ‘disobeys’ the should apply to alien life as well. Reproduction/replication second law of thermodynamics – that entropy always in- needs to be imperfect to allow for natural selection of those creases. An isolated cell cannot violate the second law branches of life with beneficial traits, otherwise life would of thermodynamics, the only way it can maintain a low- have got stuck at the first replicating organism. entropy, nonequilibrium state characterised by a high de- gree of structural organisation is to increase the entropy of The chicken and egg problem illustrates the problem of its surroundings. A cell releases some of the energy that it the definition of life and species. -
Geology of the Nuvvuagittuq Belt
Earth’s Oldest Rocks Edited by Martin J. van Kranendonk, R. Hugh Smithies and Vickie C. Bennett Developments in Precambrian Geology, Vol. 15 (K.C. Condie, Series Editor) ©2007 Elsevier B.V. All rights reserved. THE GEOLOGY OF THE 3.8 GA NUVVUAGITTUQ (PORPOISE COVE) GREENSTONE BELT, NORTHEASTERN SUPERIOR PROVINCE, CANADA. Jonathan O’Neil1, Charles Maurice2, Ross K. Stevenson3,4, Jeff Larocque5, Christophe Cloquet6, Jean David3 & Don Francis1 1 Earth & Planetary Sciences, McGill University and GÉOTOP-UQÀM-McGill, 3450 University St. Montreal, QC, Canada, H3A 2A7 ([email protected]) 2 Bureau de l’exploration géologique du Québec, Ministère des Ressources naturelles et de la Faune, 400 boul. Lamaque Val d’Or, QC, J9P 3L4 3 GÉOTOP-UQÀM-McGill, Université du Québec à Montréal, C.P. 8888, succ. centre-ville, Montreal, QC, Canada H3C 3P8 4 Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, C.P. 8888, succ. centre-ville Montreal, QC, Canada H3C 3P8 5 School of Earth and Oceanic Sciences, University of Victoria, P.O. Box 3055 STN CSC, Victoria, BC, Canada, V8W 3P6 6 INW-UGent, Department of analytical chemistry, Proeftuinstraat 86, 9000 GENT, Belgium Abstract The Nuvvuagittuq greenstone belt is a 3.8 Ga supracrustal succession preserved as a raft in remobilised tonalities along the eastern coast of Hudson Bay. The dominant lithology of the belt is a quartz-ribboned grey amphibolite composed of variable proportions of cummingtonite, biotite and plagioclase. Although the amphibolites have mafic compositions, the presence of cummingtonite rather than hornblende in these rocks reflects their low Ca contents, which may result from the alteration and metamorphism of mafic pyroclastic rocks. -
RESEARCH a Non–Plate Tectonic
RESEARCH A non–plate tectonic model for the Eoarchean Isua supracrustal belt A. Alexander G. Webb1,*, Thomas Müller2, Jiawei Zuo1, Peter J. Haproff3, and Anthony Ramírez-Salazar2 1DEPARTMENT OF EARTH SCIENCES AND LABORATORY FOR SPACE RESEARCH, UNIVERSITY OF HONG KONG, POKFULAM ROAD, HONG KONG, CHINA 2SCHOOL OF EARTH AND ENVIRONMENT, UNIVERSITY OF LEEDS, MATHS/EARTH AND ENVIRONMENT BUILDING, LEEDS LS2 9JT, UK 3DEPARTMENT OF EARTH AND OCEAN SCIENCES, UNIVERSITY OF NORTH CAROLINA, WILMINGTON, NORTH CAROLINA 28403, USA ABSTRACT The ca. 3.8–3.6-b.y.-old Isua supracrustal belt of SW Greenland is Earth’s only site older than 3.2 Ga that is exclusively interpreted via plate- tectonic theory. The belt is divided into ca. 3.8 Ga and ca. 3.7 Ga halves, and these are interpreted as plate fragments that collided by ca. 3.6 Ga. However, such models are based on idiosyncratic interpretations of field observations and U-Pb zircon data, resulting in intricate, conflicting stratigraphic and structural interpretations. We reanalyzed published geochronological work and associated field constraints previously interpreted to show multiple plate-tectonic events and conducted field-based exploration of metamorphic and structural gra- dients previously interpreted to show heterogeneities recording plate-tectonic processes. Simpler interpretations are viable, i.e., the belt may have experienced nearly homogeneous metamorphic conditions and strain during a single deformation event prior to intrusion of ca. 3.5 Ga mafic dikes. Curtain and sheath folds occur at multiple scales throughout the belt, with the entire belt potentially representing Earth’s largest a-type fold. Integrating these findings, we present a new model in which two cycles of volcanic burial and resultant melt- ing and tonalite-trondhjemite-granodiorite (TTG) intrusion produced first the ca. -
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. -
Assessing the Claim for Earth's Oldest Biogenic Graphite
1 On the true antiquity of Eoarchean chemofossils – assessing the claim for Earth’s oldest biogenic graphite in the Saglek Block of Labrador Martin J. Whitehousea, Daniel J. Dunkleyb, Monika A. Kusiakc,d, Simon A. Wildee a Department of Geosciences, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden b Faculty of Earth Sciences, University of Silesia, ul. Będzińska 60, PL-41205 Sosnowiec, Poland c Institute of Geological Sciences, Polish Academy of Sciences, Twarda 51/55 St., PL-00818 Warsaw, Poland d GeoForschungsZentrum Potsdam, 3.6 Chemistry and Physics of Earth Materials, D-14473 Potsdam, Germany e School of Earth & Planetary Sciences, Curtin University, PO Box U1987, 6845 Perth, WA, Australia Abstract A recent claim to have found traces of Earth’s earliest life (> 3.95 Ga) utilising isotopically light carbon in graphite-bearing metapelites from the Saglek Block of northern Labrador, Canada, is re-evaluated applying rigorous geological and geochronological criteria. The establishment of these criteria in previous evaluations of early life claims from southern West Greenland and northern Canada is reviewed in order to provide a backdrop to discussion of the Saglek claim. In particular, we emphasise the importance of the scale of lithological continuity in determining the veracity of such claims, which are considerably easier to demonstrate from large, relatively less tectonised supracrustal remnants like the Isua Greenstone Belt than they are from smaller, isolated enclaves of the kind found on Akilia or the highly tectonised and imbricated unit that is found in the Saglek Block. Unambiguous field relationships between ca. 3.9 Ga tonalitic gneiss and the graphite-bearing metasediments have not been demonstrated in the literature that the Saglek claim relies upon, and earlier U-Pb-Hf isotopic studies on zircon from metasediments at one of the localities used in the claim indicate a Mesoarchean to Neoarchean time of deposition. -
Precambrian Greenstone Sequences Represent Different Ophiolite Types
GR-01066; No of Pages 37 Gondwana Research xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR Focus Review Precambrian greenstone sequences represent different ophiolite types H. Furnes a,⁎, Y. Dilek b,c, M. de Wit d a Department of Earth Science and Centre for Geobiology, University of Bergen, Allégaten 41, 5007 Bergen, Norway b Department of Geology & Environmental Earth Science, Miami University, Oxford, OH 45056, USA c State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China d AEON – Africa Earth Observatory Network, and Faculty of Science, Nelson Mandela Metropolitian University 7701, Port Elizabeth, 6031, South Africa article info abstract Article history: We present here a global geochemical dataset from one hundred-and-five greenstone sequences, ranging in Received 14 March 2013 age from the Eoarchean through the Archean and Proterozoic Eons that we have examined to identify differ- Received in revised form 14 June 2013 ent ophiolite types (c.f. Dilek and Furnes, 2011) with distinct tectonic origins in the Precambrian rock record. Accepted 14 June 2013 We apply well-established discrimination systematics (built on immobile elements) of basaltic components Available online xxxx of the greenstone sequences as our geochemical proxies. The basaltic rocks are classified under two major groups, subduction-related and subduction-unrelated. This analysis suggests that ca. 85% of the greenstone Keywords: fi Precambrian greenstone belts sequences can be classi ed as subduction-related ophiolites, generated in backarc to forearc tectonic envi- Ophiolite classification ronments. -
Processes on the Young Earth and the Habitats of Early Life
EA40CH21-Arndt ARI 23 March 2012 15:30 Processes on the Young Earth and the Habitats of Early Life Nicholas T. Arndt1 and Euan G. Nisbet2 1ISTerre, CNRS UMR 5275, University of Grenoble, 38400 St-Martin d’Heres,` France; email: [email protected] 2Department of Earth Sciences, Royal Holloway, University of London, Egham Hill TW20 0EX, United Kingdom; email: [email protected] Annu. Rev. Earth Planet. Sci. 2012. 40:521–49 Keywords The Annual Review of Earth and Planetary Sciences is Hadean, Archean, komatiites, photosynthesis, crust online at earth.annualreviews.org This article’s doi: Abstract 10.1146/annurev-earth-042711-105316 Conditions at the surface of the young (Hadean and early Archean) Earth Copyright c 2012 by Annual Reviews. were suitable for the emergence and evolution of life. After an initial hot All rights reserved period, surface temperatures in the late Hadean may have been clement be- by Rice University on 04/21/14. For personal use only. 0084-6597/12/0530-0521$20.00 neath an atmosphere containing greenhouse gases over an ocean-dominated planetary surface. The first crust was mafic and it internally melted repeat- edly to produce the felsic rocks that crystallized the Jack Hills zircons. This crust was destabilized during late heavy bombardment. Plate tectonics prob- ably started soon after and had produced voluminous continental crust by Annu. Rev. Earth Planet. Sci. 2012.40:521-549. Downloaded from www.annualreviews.org the mid Archean, but ocean volumes were sufficient to submerge much of this crust. In the Hadean and early Archean, hydrothermal systems around abundant komatiitic volcanism may have provided suitable sites to host the earliest living communities and for the evolution of key enzymes. -
Evidence for 3.3-Billion-Year-Old Oceanic Crust in the Barberton Greenstone Belt, South Africa
Evidence for 3.3-billion-year-old oceanic crust in the Barberton greenstone belt, South Africa Eugene G. Grosch1* and Jiri Slama2 1Geology Department, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa 2Institute of Geology of the Czech Academy of Science, Rosvojova 269, 16500 Prague, Czech Republic ABSTRACT of the BGB and test for a continental versus juvenile oceanic setting. We Recognition of oceanic crust in Archean greenstone belts has develop a multi-pronged approach combining field observations, scientific remained a controversial and unresolved issue, with implications drill core, U-Pb detrital zircon ages, and geochemistry of metabasalts to for understanding early Earth geodynamics. In the search for early evaluate whether the sequence erupted on top of continental tonalite- Archean oceanic crust, we present a multi-pronged approach to test trondhjemite-granodiorite (TTG) crust, or whether it represents a pre- for the presence of an ophiolite-type sequence preserved in the Paleo- served remnant of accreted juvenile oceanic crust. The extent to which archean Barberton greenstone belt (BGB) of South Africa. New field the Kromberg type section potentially represents an Archean ophiolite observations are combined with detrital U-Pb zircon geochronology is assessed, with important implications for the nature of geodynamic and geochemistry on fresh drill-core material from the Kromberg processes on the early Archean Earth. type-section sequence of mafic-ultramafic rocks in the 3.56–3.33 Ga Onverwacht Group of the BGB. Trace element geochemistry indi- GEOLOGY AND SAMPLING cates that the Kromberg metabasalts were derived from the primi- The geographical location of the BGB on the border between Swaziland tive mantle. -
Geochemistry and Geodynamic Origin of the Mesoarchean Ujarassuit and Ivisaartoq Greenstone Belts, SW Greenland
Lithos 113 (2009) 133–157 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos Geochemistry and geodynamic origin of the Mesoarchean Ujarassuit and Ivisaartoq greenstone belts, SW Greenland J.C. Ordóñez-Calderón a,⁎, A. Polat a, B.J. Fryer a,b, P.W.U. Appel c, J.A.M. van Gool c, Y. Dilek d, J.E. Gagnon a,b a Department of Earth and Environmental Sciences, University of Windsor, Windsor, ON, Canada N9B 3P4 b Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada N9B 3P4 c Geological Survey of Denmark and Greenland, 1350 Copenhagen, Denmark d Department of Geology, Miami University, Oxford, OH 45056, USA article info abstract Article history: The Ivisaartoq (ca. 3075 Ma) and Ujarassuit (ca. 3070 Ma) greenstone belts are the largest Mesoarchean Received 23 May 2008 supracrustal lithotectonic assemblages in the Nuuk region, SW Greenland. Both greenstone belts underwent Accepted 5 November 2008 polyphase deformation and amphibolite facies metamorphism, and were in due course variously Available online 21 November 2008 dismembered. Pillow lavas, pillow breccia, magmatic layering, and relic sedimentary structures are well preserved in the Ivisaartoq belt. Volcanic rocks include basalts, and minor andesites and picrites. Boninite- Keywords: like rocks occur in the Ujarassuit belt. Metasedimentary rocks in the Ujarassuit belt occur as thin layers (0.5– Mesoarchean oceanic crust Greenstone belt 1.0 m) of biotite schists, and in the Ivisaartoq belt as ~500 m-thick biotite schists intercalated with minor Supra-subduction zone quartzitic gneisses. There is no field evidence indicating that the Ivisaartoq and Ujarassuit supracrustal rocks Amphibolite were deposited on older continental basement, and their volcanic rocks do not exhibit any geochemical Boninite trends indicating contamination by Archean upper continental crust.