DOCSLIB.ORG

Convective Isolation of Hadean Mantle Reservoirs Through Archean Time

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Convective Isolation of Hadean Mantle Reservoirs Through Archean Time Convective isolation of Hadean mantle reservoirs through Archean time Jonas Tuscha,1, Carsten Münkera, Eric Hasenstaba, Mike Jansena, Chris S. Mariena, Florian Kurzweila, Martin J. Van Kranendonkb,c, Hugh Smithiesd, Wolfgang Maiere, and Dieter Garbe-Schönbergf aInstitut für Geologie und Mineralogie, Universität zu Köln, 50674 Köln, Germany; bSchool of Biological, Earth and Environmental Sciences, The University of New South Wales, Kensington, NSW 2052, Australia; cAustralian Center for Astrobiology, The University of New South Wales, Kensington, NSW 2052, Australia; dDepartment of Mines, Industry Regulations and Safety, Geological Survey of Western Australia, East Perth, WA 6004, Australia; eSchool of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, United Kingdom; and fInstitut für Geowissenschaften, Universität zu Kiel, 24118 Kiel, Germany Edited by Richard W. Carlson, Carnegie Institution for Science, Washington, DC, and approved November 18, 2020 (received for review June 19, 2020) Although Earth has a convecting mantle, ancient mantle reservoirs anomalies in Eoarchean rocks was interpreted as evidence that that formed within the first 100 Ma of Earth’s history (Hadean these rocks lacked a late veneer component (5). Conversely, the Eon) appear to have been preserved through geologic time. Evi- presence of some late accreted material is required to explain the dence for this is based on small anomalies of isotopes such as elevated abundances of highly siderophile elements (HSEs) in 182W, 142Nd, and 129Xe that are decay products of short-lived nu- Earth’s modern silicate mantle (9). Notably, some Archean rocks clide systems. Studies of such short-lived isotopes have typically with apparent pre-late veneer like 182W isotope excesses were focused on geological units with a limited age range and therefore shown to display HSE concentrations that are indistinguishable only provide snapshots of regional mantle heterogeneities. Here from modern mantle abundances (10, 11), which is difficult to 182 182 we present a dataset for short-lived Hf− W (half-life 9 Ma) in reconcile with the missing late veneer hypothesis. An alternative a comprehensive rock suite from the Pilbara Craton, Western Aus- suggestion is therefore that early silicate differentiation during tralia. The samples analyzed preserve a unique geological archive 182 182 the lifetime of Hf might have caused the formation of mantle covering 800 Ma of Archean history. Pristine W signatures that reservoirs with anomalous 182W signatures (10, 12). In addition, directly reflect the W isotopic composition of parental sources are recent studies have revealed variable 182W isotope deficits in the only preserved in unaltered mafic samples with near canonical mantle plume sources of ocean island basalts (13). In line with W/Th (0.07 to 0.26). Early Paleoarchean, mafic igneous rocks from EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES noble gas systematics and seismic properties of such deep-rooted the East Pilbara Terrane display a uniform pristine μ182W excess of mantle plumes, these 182W deficits have been taken as evidence 12.6 ± 1.4 ppm. From ca. 3.3Ga onward, the pristine 182W signa- tures progressively vanish and are only preserved in younger rocks for the presence of primordial domains that have been con- vectively isolated since Earth’s earliest history (13). The origin of of the craton that tap stabilized ancient lithosphere. Given that the – anomalous 182W signature must have formed by ca. 4.5 Ga, the this modern igneous reservoir remains ambiguous (14 16), and mantle domain that was tapped by magmatism in the Pilbara Cra- its presence in pre-Phanerozoic time is highly speculative. ton must have been convectively isolated for nearly 1.2 Ga. This However, the contribution of modern mantle plume sources with 182 finding puts lower bounds on timescale estimates for localized W deficits to the convecting mantle offers an additional ex- ENVIRONMENTAL SCIENCES 182 convective homogenization in early Earth’s interior and on the planation for the decrease of W isotope excesses since the widespread emergence of plate tectonics that are both important Archean as a consequence of increasing mantle homogenization input parameters in many physical models. (SI Appendix). late veneer | Pilbara Craton | tungsten isotopes | early Earth | mantle Significance convection Geological processes like mantle convection or plate tectonics mong the terrestrial planets, Earth is unique in that plate are an essential factor controlling Earth’s habitability. Our Atectonic processes efficiently mix and homogenize its silicate study provides insights into timescales of convective homo- mantle. Surprisingly, however, geochemical studies have revealed genization of Earth’s early mantle, employing the novel tool of that both Archean and Phanerozoic mantle reservoirs still carry high-precision 182W isotope measurements to rocks from the primordial geochemical signatures, thus escaping efficient con- Pilbara Craton in Australia, that span an age range from 3.5 182 vective homogenization as also predicted by geodynamic models billion years to 2.7 billion years. Previous W studies mostly (1, 2). The main evidence for such ancient geochemical hetero- covered snapshots through geologic time, so the long-term 182 geneities stems from noble gas systematics (3) and from short- W evolution of the mantle has been ambiguous. Together lived nuclide decay series that became extinct after the Hadean with sophisticated trace element approaches, we can now eon (>4.0 Ga) (4, 5). For instance, the relative abundance of provide an improved insight into such timescales, arguing for daughter isotopes from short-lived nuclide series such as 142Nd local preservation of primordial geochemical heterogeneities within Earth’s mantle as late as around 3.0 billion years, the and 182W shows significant variations in ancient rocks when putative onset of widespread plate tectonics on Earth. compared to Earth’s modern mantle composition (4, 5). From 182 –182 these short-lived isotope systems, the Hf W decay system Author contributions: J.T. and C.M. designed research; J.T. performed research; J.T., M.J., has proven particularly useful in constraining the timing of C.S.M., W.M., and D.G.-S. contributed new reagents/analytic tools; J.T. analyzed data; and planetary core formation (6), timescales of late accretion, and J.T., C.M., E.H., F.K., M.J.V.K., and H.S. wrote the paper. silicate differentiation (7, 8). The authors declare no competing interest. 182 There are two competing explanations for the origin of W This article is a PNAS Direct Submission. isotope anomalies found in the terrestrial rock record, arising Published under the PNAS license. from the markedly different geochemical behavior of Hf and W 1To whom correspondence may be addressed. Email: [email protected]. during both core formation and silicate differentiation in plan- This article contains supporting information online at https://www.pnas.org/lookup/suppl/ 182 etary bodies. As primitive meteorites exhibit strong W isotope doi:10.1073/pnas.2012626118/-/DCSupplemental. 182 182 deficits (μ W = −190) (6), the observation of positive W Published December 21, 2020. PNAS 2021 Vol. 118 No. 2 e2012626118 https://doi.org/10.1073/pnas.2012626118 | 1of6 Downloaded by guest on September 28, 2021 Surprisingly few studies have directly assessed the 182W record supersuites of sodic (tonalites, trondhjemites, and granodiorites) of mantle-derived rock assemblages that span a relatively long and potassic granitoids (granites) that can be regarded as probes time frame of Archean geodynamic evolution. Arguably, there of early mafic crust. The younger evolution of the EPT involved are already comprehensive studies available from the Slave plume-initiated rifting (Soanesville Group) at 3.18 Ga and sub- Craton (17), southwest Greenland (12, 18), and southern Africa sequent accretion (3.07 Ga) of the younger WPS that also in- (19) that investigated lithostratigraphic successions covering time cludes ∼3.1-Ga subduction-related mafic lithologies (Whundo series of several hundred million years. However, these studies Group) (30, 31). After amalgamation, postorogenic, lithosphere- only covered crustal reservoirs (Tonalite-throndhjemite-grano- derived magmatism included mafic rocks from the Bookingarra diorite rocks [TTGs] and diamictites) but not mafic rocks that Group (Opaline Well Intrusion, Louden Volcanics, and Mount allow direct tracing of mantle-derived magmatic pulses. Notably, Negri Volcanics) and crust-derived posttectonic granites (e.g., fluid mobility of W already may have caused significant distur- Split Rock Supersuite) (27). bance of primary 182W isotope systematics in hydrated mafic We employed two strategies in selecting our samples. First, we precursors of such previously investigated TTG suites (17, 20, analyzed mafic volcanic rocks that tapped the ambient as- 21). Hence, W/Th ratios of TTGs may not necessarily reflect the thenospheric mantle of the EPT (plume derived) and the WPS primary W/Th ratios of their mafic precursors. In fact, sub- (subduction related). Secondly, to understand the evolution of canonical W/Th ratios are often observed in TTGs (e.g., ref. 22), the lithosphere and to obtain average crustal compositions, we that may reflect 1) preferential loss of W during dehydration at analyzed mafic dikes, sediments, and granitoids of different ages. amphibolite facies conditions prior to partial anataxis or 2) We studied a total of 56 samples from more
Load more

Recommended publications
  • Large and Robust Lenticular Microorganisms on the Young Earth ⇑ ⇑ Dorothy Z
    Precambrian Research 296 (2017) 112–119 Contents lists available at ScienceDirect Precambrian Research journal homepage: www.elsevier.com/locate/precamres Large and robust lenticular microorganisms on the young Earth ⇑ ⇑ Dorothy Z. Oehler a, , Maud M. Walsh b, Kenichiro Sugitani c, Ming-Chang Liu d, Christopher H. House e, a Planetary Science Institute, Tucson, AZ 85719, USA b School of Plant, Environmental and Soil Sciences, Louisiana State University, Baton Rouge, LA 70803-2110, USA c Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan d Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095-1567, USA e Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA article info abstract Article history: In recent years, remarkable organic microfossils have been reported from Archean deposits in the Pilbara Received 18 November 2016 craton of Australia. The structures are set apart from other ancient microfossils by their complex lentic- Revised 29 March 2017 ular morphology combined with their large size and robust, unusually thick walls. Potentially similar Accepted 11 April 2017 forms were reported in 1992 from the 3.4 Ga Kromberg Formation (KF) of the Kaapvaal craton, South Available online 26 April 2017 Africa, but their origin has remained uncertain. Here we report the first determination of in situ carbon isotopic composition (d13C) of the lenticular structures in the KF (obtained with Secondary Ion Mass Keywords: Spectrometry [SIMS]) as well as the first comparison of these structures to those from the Pilbara, using Archean morphological, isotopic, and sedimentological criteria. Spindle Lenticular Our results support interpretations that the KF forms are bona fide, organic Archean microfossils and Microfossil represent some of the oldest morphologically preserved organisms on Earth.
    [Show full text]
  • Timeline of Natural History
    Timeline of natural history This timeline of natural history summarizes significant geological and Life timeline Ice Ages biological events from the formation of the 0 — Primates Quater nary Flowers ←Earliest apes Earth to the arrival of modern humans. P Birds h Mammals – Plants Dinosaurs Times are listed in millions of years, or Karo o a n ← Andean Tetrapoda megaanni (Ma). -50 0 — e Arthropods Molluscs r ←Cambrian explosion o ← Cryoge nian Ediacara biota – z ←Earliest animals o ←Earliest plants i Multicellular -1000 — c Contents life ←Sexual reproduction Dating of the Geologic record – P r The earliest Solar System -1500 — o t Precambrian Supereon – e r Eukaryotes Hadean Eon o -2000 — z o Archean Eon i Huron ian – c Eoarchean Era ←Oxygen crisis Paleoarchean Era -2500 — ←Atmospheric oxygen Mesoarchean Era – Photosynthesis Neoarchean Era Pong ola Proterozoic Eon -3000 — A r Paleoproterozoic Era c – h Siderian Period e a Rhyacian Period -3500 — n ←Earliest oxygen Orosirian Period Single-celled – life Statherian Period -4000 — ←Earliest life Mesoproterozoic Era H Calymmian Period a water – d e Ectasian Period a ←Earliest water Stenian Period -4500 — n ←Earth (−4540) (million years ago) Clickable Neoproterozoic Era ( Tonian Period Cryogenian Period Ediacaran Period Phanerozoic Eon Paleozoic Era Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Permian Period Mesozoic Era Triassic Period Jurassic Period Cretaceous Period Cenozoic Era Paleogene Period Neogene Period Quaternary Period Etymology of period names References See also External links Dating of the Geologic record The Geologic record is the strata (layers) of rock in the planet's crust and the science of geology is much concerned with the age and origin of all rocks to determine the history and formation of Earth and to understand the forces that have acted upon it.
    [Show full text]
  • Gangidine NASA Early Career Collaboration Follow-Up
    NASA Astrobiology Early Career Collaboration Award Follow-up Report Andrew Gangidine, Ph.D Candidate, University of Cincinnati Project Title: A Step Back in Time – Ancient Hot Springs and the Search for Life on Mars Collaborator: Dr. Martin Van Kranendonk, UNSW, Australian Center for Astrobiology During Summer 2018 I travel to the Pilbara Craton in Western Australia in search of the earliest known evidence of life on land. Here I met up with Dr. Martin Van Kranendonk, director of the Australian Center for Astrobiology and expert on the Pilbara geology. Over the next two weeks, we traveled to many previously established sites of interest containing stromatolitic textures and evidence of past terrestrial hot spring activity, as well as new sites of interest which provided further evidence supporting the terrestrial hot spring hypothesis. Over the course of these two weeks, I collected samples of ~3.5Ga microbial textures in order to analyze such samples for their biosignature preservation potential. I also was able to spend some time mapping the Pilbara in order to understand the greater regional geologic context of the samples I collected. After this field work, Dr. Van Kranendonk and I returned to Sydney, where I met with Dr. Malcolm Walter at the University of New South Wales. Dr. Walter allowed me to search through the sample archive of the Australian Center for Astrobiology, where I collected younger samples from the mid-Paleozoic from terrestrial hydrothermal deposits. With these samples, I am able to perform a comparison study between modern, older, and ancient hydrothermal deposits in order to characterize what happens to potential biosignatures in these environments throughout geologic time.
    [Show full text]
  • Bayesian Analysis of the Astrobiological Implications of Life's
    Bayesian analysis of the astrobiological implications of life's early emergence on Earth David S. Spiegel ∗ y, Edwin L. Turner y z ∗Institute for Advanced Study, Princeton, NJ 08540,yDept. of Astrophysical Sciences, Princeton Univ., Princeton, NJ 08544, USA, and zInstitute for the Physics and Mathematics of the Universe, The Univ. of Tokyo, Kashiwa 227-8568, Japan Submitted to Proceedings of the National Academy of Sciences of the United States of America Life arose on Earth sometime in the first few hundred million years Any inferences about the probability of life arising (given after the young planet had cooled to the point that it could support the conditions present on the early Earth) must be informed water-based organisms on its surface. The early emergence of life by how long it took for the first living creatures to evolve. By on Earth has been taken as evidence that the probability of abiogen- definition, improbable events generally happen infrequently. esis is high, if starting from young-Earth-like conditions. We revisit It follows that the duration between events provides a metric this argument quantitatively in a Bayesian statistical framework. By (however imperfect) of the probability or rate of the events. constructing a simple model of the probability of abiogenesis, we calculate a Bayesian estimate of its posterior probability, given the The time-span between when Earth achieved pre-biotic condi- data that life emerged fairly early in Earth's history and that, billions tions suitable for abiogenesis plus generally habitable climatic of years later, curious creatures noted this fact and considered its conditions [5, 6, 7] and when life first arose, therefore, seems implications.
    [Show full text]
  • THE ARCHAEAN and Earllest PROTEROZOIC EVOLUTION and METALLOGENY of Australla
    Revista Brasileira de Geociências 12(1-3): 135-148, Mar.-Sel.. 1982 - Silo Paulo THE ARCHAEAN AND EARLlEST PROTEROZOIC EVOLUTION AND METALLOGENY OF AUSTRALlA DA VID I. OROVES' ABSTRACT Proterozoic fold belts in Austrália developed by lhe reworking of Archaean base­ mcnt. The nature of this basement and the record of Archaean-earliest Proterozoic evolution and metallogeny is best prescrved in the Western Australian Shield. ln the Yilgarn Craton. a poorly-mineralized high-grade gneiss terrain rccords a complex,ca. 1.0 b.y. history back to ca. 3.6b.y. This terrain is probably basement to lhe ca. 2.9~2.7 b.y. granitoid­ -greenstone terrains to lhe east-Cratonization was essentially complete by ca, 2.6 b.y. Evolution of the granitoid-greenstone terrains ofthe Pilbara Craton occurred between ca. 3.5b.y. ano 2.8 b.y. The Iectonic seuing of ali granitoid-greenstone terrains rcmains equivocaI. Despitc coincidcnt cale­ -alkalinc volcanism and granitoid emplacemcnt , and broad polarity analogous to modem are and marginal basin systcrns. thcre is no direct evidencc for plate tectonic processes. Important diffcrences in regional continuity of volcanic scqucnccs, lithofacies. regional tectonic pauerns and meta1Jogeny of lhe terrains may relate to the amount of crusta! extension during basin formation. At onc extreme, basins possibly reprcsenting low total cxrensíon (e.g. east Pilbara l are poorly mi­ ncralizcd with some porphyry-stylc Mo-Cu and small sulphute-rich volcanogenic 01' evaporitic deposits reflecting the resultam subaerial to shaJlow-water environment. ln contrast, basins inter­ prctcd to have formcd during greater crusta! cxrcnsion (e.g.
    [Show full text]
  • The Geologic Time Scale Is the Eon
    Exploring Geologic Time Poster Illustrated Teacher's Guide #35-1145 Paper #35-1146 Laminated Background Geologic Time Scale Basics The history of the Earth covers a vast expanse of time, so scientists divide it into smaller sections that are associ- ated with particular events that have occurred in the past.The approximate time range of each time span is shown on the poster.The largest time span of the geologic time scale is the eon. It is an indefinitely long period of time that contains at least two eras. Geologic time is divided into two eons.The more ancient eon is called the Precambrian, and the more recent is the Phanerozoic. Each eon is subdivided into smaller spans called eras.The Precambrian eon is divided from most ancient into the Hadean era, Archean era, and Proterozoic era. See Figure 1. Precambrian Eon Proterozoic Era 2500 - 550 million years ago Archaean Era 3800 - 2500 million years ago Hadean Era 4600 - 3800 million years ago Figure 1. Eras of the Precambrian Eon Single-celled and simple multicelled organisms first developed during the Precambrian eon. There are many fos- sils from this time because the sea-dwelling creatures were trapped in sediments and preserved. The Phanerozoic eon is subdivided into three eras – the Paleozoic era, Mesozoic era, and Cenozoic era. An era is often divided into several smaller time spans called periods. For example, the Paleozoic era is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous,and Permian periods. Paleozoic Era Permian Period 300 - 250 million years ago Carboniferous Period 350 - 300 million years ago Devonian Period 400 - 350 million years ago Silurian Period 450 - 400 million years ago Ordovician Period 500 - 450 million years ago Cambrian Period 550 - 500 million years ago Figure 2.
    [Show full text]
  • Soils in the Geologic Record
    in the Geologic Record 2021 Soils Planner Natural Resources Conservation Service Words From the Deputy Chief Soils are essential for life on Earth. They are the source of nutrients for plants, the medium that stores and releases water to plants, and the material in which plants anchor to the Earth’s surface. Soils filter pollutants and thereby purify water, store atmospheric carbon and thereby reduce greenhouse gasses, and support structures and thereby provide the foundation on which civilization erects buildings and constructs roads. Given the vast On February 2, 2020, the USDA, Natural importance of soil, it’s no wonder that the U.S. Government has Resources Conservation Service (NRCS) an agency, NRCS, devoted to preserving this essential resource. welcomed Dr. Luis “Louie” Tupas as the NRCS Deputy Chief for Soil Science and Resource Less widely recognized than the value of soil in maintaining Assessment. Dr. Tupas brings knowledge and experience of global change and climate impacts life is the importance of the knowledge gained from soils in the on agriculture, forestry, and other landscapes to the geologic record. Fossil soils, or “paleosols,” help us understand NRCS. He has been with USDA since 2004. the history of the Earth. This planner focuses on these soils in the geologic record. It provides examples of how paleosols can retain Dr. Tupas, a career member of the Senior Executive Service since 2014, served as the Deputy Director information about climates and ecosystems of the prehistoric for Bioenergy, Climate, and Environment, the Acting past. By understanding this deep history, we can obtain a better Deputy Director for Food Science and Nutrition, and understanding of modern climate, current biodiversity, and the Director for International Programs at USDA, ongoing soil formation and destruction.
    [Show full text]
  • Using Volcaniclastic Rocks to Constrain Sedimentation Ages
    Using volcaniclastic rocks to constrain sedimentation ages: To what extent are volcanism and sedimentation synchronous? Camille Rossignol, Erwan Hallot, Sylvie Bourquin, Marc Poujol, Marc Jolivet, Pierre Pellenard, Céline Ducassou, Thierry Nalpas, Gloria Heilbronn, Jianxin Yu, et al. To cite this version: Camille Rossignol, Erwan Hallot, Sylvie Bourquin, Marc Poujol, Marc Jolivet, et al.. Using vol- caniclastic rocks to constrain sedimentation ages: To what extent are volcanism and sedimentation synchronous?. Sedimentary Geology, Elsevier, 2019, 381, pp.46-64. 10.1016/j.sedgeo.2018.12.010. insu-01968102 HAL Id: insu-01968102 https://hal-insu.archives-ouvertes.fr/insu-01968102 Submitted on 2 Jan 2019 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. Accepted Manuscript Using volcaniclastic rocks to constrain sedimentation ages: To what extent are volcanism and sedimentation synchronous? Camille Rossignol, Erwan Hallot, Sylvie Bourquin, Marc Poujol, Marc Jolivet, Pierre Pellenard, Céline Ducassou, Thierry Nalpas, Gloria Heilbronn, Jianxin Yu, Marie-Pierre
    [Show full text]
  • 38—GEOLOGIC AGE SYMBOL FONT (Stratagemage) REF NO STRATIGRAPHIC AGE SUBDIVISION TYPE AGE SYMBOL KEYBOARD POSITION for Stratagemage FONT
    Federal Geographic Data Committee U.S. Geological Survey Open-File Report 99–430 Public Review Draft - Digital Cartographic Standard for Geologic Map Symbolization PostScript Implementation (filename: of99-430_38-01.eps) 38—GEOLOGIC AGE SYMBOL FONT (StratagemAge) REF NO STRATIGRAPHIC AGE SUBDIVISION TYPE AGE SYMBOL KEYBOARD POSITION FOR StratagemAge FONT 38.1 Archean Eon A Not applicable (use Helvetica instead) 38.2 Cambrian Period _ (underscore = shift-hyphen) 38.3 Carboniferous Period C Not applicable (use Helvetica instead) 38.4 Cenozoic Era { (left curly bracket = shift-left square bracket) 38.5 Cretaceous Period K Not applicable (use Helvetica instead) 38.6 Devonian Period D Not applicable (use Helvetica instead) 38.7 Early Archean (3,800(?)–3,400 Ma) Era U Not applicable (use Helvetica instead) 38.8 Early Early Proterozoic (2,500–2,100 Ma) Era R (capital R = shift-r) 38.9 Early Middle Proterozoic (1,600–1,400 Ma) Era G (capital G = shift-g) 38.10 Early Proterozoic Era X Not applicable (use Helvetica instead) 38.11 Eocene Epoch # (pound sign = shift-3) 38.12 Holocene Epoch H Not applicable (use Helvetica instead) 38.13 Jurassic Period J Not applicable (use Helvetica instead) 38.14 Late Archean (3,000–2,500 Ma) Era W Not applicable (use Helvetica instead) 38.15 Late Early Proterozoic (1,800–1,600 Ma) Era I (capital I = shift-i) 38.16 Late Middle Proterozoic (1,200–900 Ma) Era E (capital E = shift-e) 38.17 Late Proterozoic Era Z Not applicable (use Helvetica instead) 38.18 Mesozoic Era } (right curly bracket = shift-right square bracket) 38.19 Middle Archean (3,400–3,000 Ma) Era V Not applicable (use Helvetica instead) 38.20 Middle Early Proterozoic (2,100–1,800 Ma) Era L (capital L = shift-l) 38.21 Middle Middle Proterozoic (1,400–1,200 Ma) Era F (capital F = shift-f) 38.22 Middle Proterozoic Era Y Not applicable (use Helvetica instead) A–38–1 Federal Geographic Data Committee U.S.
    [Show full text]
  • Geologic Time Lesson Guide Lesson Guide | Description
    Geologic Time Lesson Guide Lesson Guide | Description Instructor: Dr. Michael T. Lewchuk Grade Level: 6 - 12 Subject: Earth & Physical Science Students will investigate the subdivisions of the Geologic Time Scale. Wonder How: Have you ever wondered how scientists and geologists know how old something is? Goal: Students will gather data and use ratios that will help them create a scale model of Geological time using simple materials found at home. Lesson Guide | Lesson Guide Agenda Lesson Guide Agenda: v Vocabulary v Materials List v Geologic Time Scale v Activity Instructions v Challenge! v Additional Resources v Oklahoma Academic Standards Lesson Guide | Vocabulary Eon – An Eon is the fundamental division of time in Geology. The Earth’s 4.6-billion- year history is divided into four Eons: Hadean, Archean, Proterozoic and Phanerozoic. Precambrian Supereon – This is the combination of the Hadean, Archean and Proterozoic Eons. It is subdivided based on the physical properties of the Earth’s surface and atmosphere. Hadean Eon – The Hadean is the oldest Eon. It is generally described as the time when the Earth was so hot that it was all, or mostly all, molten liquid. Archean Eon – The Archean Eon is generally described as the time when solid rock existed on the surface of the Earth, but little or no free oxygen existed in the atmosphere. Proterozoic Eon – The Proterozoic is generally considered the Eon when free oxygen began to appear in the atmosphere. Microscopic life developed during the Proterozoic. Lesson Guide | Vocabulary Phanerozoic Eon – The Phanerozoic Eon is the most recent Eon in geologic history.
    [Show full text]
  • 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.
    [Show full text]
  • The World Turns Over: Hadean–Archean Crust–Mantle Evolution
    Lithos 189 (2014) 2–15 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos Review paper The world turns over: Hadean–Archean crust–mantle evolution W.L. Griffin a,⁎, E.A. Belousova a,C.O'Neilla, Suzanne Y. O'Reilly a,V.Malkovetsa,b,N.J.Pearsona, S. Spetsius a,c,S.A.Wilded a ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and GEMOC, Dept. Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia b VS Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090, Russia c Scientific Investigation Geology Enterprise, ALROSA Co Ltd, Mirny, Russia d ARC Centre of Excellence for Core to Crust Fluid Systems, Dept of Applied Geology, Curtin University, G.P.O. Box U1987, Perth 6845, WA, Australia article info abstract Article history: We integrate an updated worldwide compilation of U/Pb, Hf-isotope and trace-element data on zircon, and Re–Os Received 13 April 2013 model ages on sulfides and alloys in mantle-derived rocks and xenocrysts, to examine patterns of crustal evolution Accepted 19 August 2013 and crust–mantle interaction from 4.5 Ga to 2.4 Ga ago. The data suggest that during the period from 4.5 Ga to ca Available online 3 September 2013 3.4 Ga, Earth's crust was essentially stagnant and dominantly maficincomposition.Zirconcrystallizedmainly from intermediate melts, probably generated both by magmatic differentiation and by impact melting. This quies- Keywords: – Archean cent state was broken by pulses of juvenile magmatic activity at ca 4.2 Ga, 3.8 Ga and 3.3 3.4 Ga, which may Hadean represent mantle overturns or plume episodes.
    [Show full text]