DOCSLIB.ORG

American Journal of Science,Vol

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
American Journal of Science,Vol [AMERICAN JOURNAL OF SCIENCE,VOL. 299, MARCH, 1999, P. 173–209] American Journal of Science MARCH 1999 ASSESSMENT OF FELDSPAR SOLUBILITY CONSTANTS IN WATER IN THE RANGE 0° TO 350°C AT VAPOR SATURATION PRESSURES STEFA´ N ARNO´ RSSON and ANDRI STEFA´ NSSON Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavı´k, Iceland ABSTRACT. The equilibrium constants for endmember feldspar hydrolysis for the following reactions ؉ ؉ ؊ ؉ 0 ؍ ؉ NaAlSi3O8 8H2O Na Al(OH)4 3H4SiO4 ؉ ؉ ؊ ؉ 0 ؍ ؉ KAlSi3O8 8H2O K Al(OH)4 3H4SiO4 ؉2 ؉ ؊ ؉ 0 ؍ ؉ CaAl2Si2O8 8H2O Ca 2Al(OH)4 2H4SiO4 are accurately described by ؊ ؉ 2؊ ؊ ؊6 2؉ log Klow-albite 96.267 305,542/T 3985.50/T 28.588 · 10 ·T 35.790 · log T ؊ ؉ 2؊ ؊ ؊6 2؉ log Khigh-albite 97.275 306,065/T 3313.51/T 28.622 · 10 ·T 35.851 · log T ؊ ؉ 2؊ ؊ ؊6 2؉ log Kmicrocline 78.594 311,970/T 6068.38/T 27.776 · 10 ·T 30.308 · log T ؊ ؉ 2؊ ؊ ؊6 2؉ log Ksanidine 77.837 316,431/T 5719.10/T 27.712 · 10 ·T 29.738 · log T ؊ ؉ 2؊ ؊ ؊6 2؉ log Kanorthite 88.591 326,546/T 2720.61/T 40.100 · 10 ·T 31.168 · log T where T is in K. They are valid in the range 0° to 350°C, at 1 bar below 100°C and at vapor saturation pressures (Psat) at higher temperatures. The equations for low-albite and microcline are valid for Amelia albite and for microcline with the -respectively. The same kind of log K ,(0.95 ؍ same degree of Al-Si order (Z temperature equations have also been retrieved for alkali-feldspar and plagio- clase solid solutions (tables 4 and 6). The calculated feldspar equilibrium constants of this study indicate much higher solubility under weathering conditions than generally accepted to date, the difference being more than one and a half orders of magnitude at 0°C for both high- and low-albite, but somewhat less for microcline, sanidine, and anorthite. This higher solubility is largely a consequence of new data for the thermody- 0 namic properties of H4SiO4. The present results have a particularly important bearing on the stability of feldspars under weathering conditions and the study of interaction between water and rock/soil in this environment. They are, however, also important for the study of equilibrium/dis-equilibrium conditions in active geothermal systems. INTRODUCTION Knowledge of the thermodynamic properties of feldspars and of the aqueous species that form when they dissolve in water is essential for quantitative interpretation of interactions between these minerals and natural waters. Studies of mineral saturation in aqueous solutions involve essentially two steps: (1) derivation of equilibrium constants (K) for mineral hydrolysis from thermodynamic data taking into account the effects of variable composition of the minerals and ordering, as appropriate, and (2) calculation of individual aqueous species activities from analytical data on the waters to retrieve values ⌬ for the respective activity products (Q). The Gibbs energy of any reaction, Gr, is defined 173 174 S. Arno´rsson and A. Stefa´nsson—Assessment of feldspar solubility as: ⌬ ϭ⌬ 0 ϩ Gr Gr RT ln Q (1) where Q is the activity product (reaction quotient) for the reaction; R, the gas constant; T, ⌬ 0 temperature in Kelvin; and Gr , the standard Gibbs energy of the reaction, which is equal to ϪRT ln K where K represents the equilibrium constant. For the following general reaction: aA ϩ bB _ cC ϩ dD (2) the activity product is defined as ac · ad ϭ C D Q a b (3) aA · aB ⌬ ϭ ϭ a denotes the activity of the subscribed species. At equilibrium Gr 0soK Qat equilibrium. In this contribution calorimetric and other thermodynamic data on the feldspars have been compiled and assessed with the purpose of deriving temperature equations describing their solubility constants (K) in the range 0° to 350°C at 1 bar below 100°C and at vapor saturation pressures (Psat) at higher temperatures. Solubility constants are presented for both fully ordered and fully disordered alkali-feldspars with respect to Al and Si (low-albite high-albite, microcline, sanidine) and anorthite as well as solid solutions of low-albite/microcline, high-albite/sanidine, and of the ‘‘low’’ and ‘‘high’’ plagioclase series. The specified temperature and pressure ranges cover the P-T environ- ment of almost all natural waters assessable for sampling: surface waters, springs, wellheads, and downhole. Comparison between the values taken by these solubility constants (K) and activity products (Q) calculated with the aid of aqueous speciation programs such as WATCH (Arno´ rsson, Sigurdsson, and Svavarsson, 1982), EQ-3 (Wolery, 1992), WATEQ (Ball and Nordstrom, 1991), SOLMNEQ (Kharaka and others, 1988) and pH-CALC (Spycher and Reed, 1989) allows evaluation of saturation states of waters with respect to feldspars as a function of their composition and Al-Si ordering. In igneous and high grade metamorphic rocks, feldspars form plagioclase and alkali feldspar solid solutions that are, at least, partly disordered with respect to Al and Si. In the greenschist and lower temperature metamorphic facies, as well as in hydrothermally altered rocks, the feldspars are essentially pure sodium and potassium feldspars (Miya- shiro, 1994). Due to their low formation temperatures one would expect them to be largely ordered unless the phase that initially precipitates is disordered. Field data in this respect are lacking. The thermodynamic stability of feldspars is much affected by their Al-Si ordering (Waldbaum and Robie, 1971; Hovis and Waldbaum, 1977; Helgeson and others, 1978; Carpenter, McConnell, and Navrotsky, 1985; Salje, 1985; Salje and others, 1985; Berman, 1988; Hovis, 1988; Holland and Powell, 1992; Navrotsky, 1989) making disordered feldspars more soluble in water than ordered ones at low temperatures (less than ϳ300°C). As a result natural waters may be simultaneously dissolving disordered feldspars of igneous or metamorphic origin and precipitating ordered ones under hydrothermal conditions. Many researchers have carried out calorimetric experiments to retrieve data on the standard enthalpy of formation from the elements of K-feldspar, albite, and anorthite at 25°C and 1 bar (Kracek and Neuvonen, 1952; Kracek, 1953; Barany, 1962; Waldbaum, 1966, 1968; Waldbaum and Robie, 1971; Hemingway and Robie, 1977; Charlu, Newton, and Kleppa, 1978; Newton, Charlu, and Kleppa, 1980; Navrotsky and others, 1980; Hovis, 1982, 1988; Carpenter, McConnell, and Navrotsky, 1985; Kieseleva and others, 1990; Zhu, Newton, and Kleppa, 1994). Heat capacity measurements have also constants in water in the range 0° to 350°C at vapor saturation pressures 175 been carried out to obtain data on the absolute entropy of these feldspars and heat capacity-temperature relationships (Openshaw and others, 1976; Krupka, Robie, and Hemingway, 1979; Hemingway, Krupka, and Robie, 1981). When feldspars dissolve in natural waters many aqueous species form. Their relative abundance depends largely on the water pH, salinity, and temperature. In ϩ ϩ ϩ2 0 Ϫ relatively dilute waters with alkaline pH Na ,K ,Ca ,H4SiO4, and Al(OH)4 are the dominent feldspar-derived species in the temperature range 0° to 350°C and, according Ϫ Ϫ Ϫ1 to recent experiments, also the alumina-silica complex [(OH)3Al O Si(OH)3] (Pokrovski and others (1998). The thermodynamic properties of the first listed species have been established accurately in the range 0° to 350°C (Apps, Neil, and Jun, 1989; Pokrovskii and Helgeson, 1995; Diakonov and others, 1996; Rimstidt, 1997; Arno´ rsson and Andre´sdo´ ttir, 1999; Shock and Helgeson, 1988; Gunnarsson and Arno´ rsson, 1999). Thus, if the thermodynamic properties of the feldspars themselves are also accurately known, so are their equilibrium constants, when expressed in terms of these aqueous species. 0 In most natural waters silica exists largely as H4SiO4. However in alkaline waters Ͼ Ϫ (pH 9.5) an appreciable fraction of the dissolved silica occurs as H3SiO4 . The first ionization constant of silicic acid is quite accurately known over a large temperature range (Seward, 1974; Busey and Mesmer, 1977) allowing the concentration of the 0 H4SiO4 species to be calculated with good precision from analytical data on total dissolved silica. Ϫ Some disagreement still exists on the dissociation constants of Al(OH)4 and 0 Ϫ Al(OH)3. The aluminate ion (Al(OH)4 ) tends to dominate in geothermal waters although the neutral Al-hydroxy species is sometimes important. In many surface waters and 0 ϩ non-thermal groundwaters Al(OH)3 and Al(OH)2 are apparently the most abundant Al-hydroxy species. Therefore, the largest uncertainty involved in retrieving activity products (Q) for feldspar-water reactions lies in the calculation of the activities of individual aluminium species except where one can be certain that the dominant aqueous Al-hydroxy species is the aluminate ion. Assessment of the state of saturation of a wide variety of natural waters with respect to endmember and solid solution feldspars will be the subject of another contribution (Stefa´nsson and Arno´ rsson, 1999). EXPERIMENTAL THERMODYNAMIC DATA Various techniques have been used to obtain data on the thermodynamic properties of minerals. For obtaining such data at relatively low temperatures the most important ones are heat capacity and heat of solution measurements and solubility experiments. However, low temperature thermodynamic data have also been retrieved by extrapola- tion of high temperature phase equilibrium experimental results (Helgeson and others, 1978; Berman, 1988; Holland and Powell, 1990, 1998; Gottschalk, 1997). In the case of the feldspars calorimetric measurements are considered to be the most useful in assessing their thermodynamic properties at low temperatures. The results of these measurements are reviewed below. In publications on the results of thermodynamic experiments the error of measure- ment is sometimes reported, but sometimes it is not.
Load more

Recommended publications
  • Iligh Resolution Solid-State Sodium-23, Aluminum-27, and Silicon-29
    American Mineralogist, Volume 70, pages 106-123,I9E5 Iligh resolution solid-statesodium-23, aluminum-27, and silicon-29nuclear magnetic resonancespectroscopic reconnaissance of alkali and plagioclasefeldspars R. JeMes Ktnrpernrcr Department of Geology University of lllinois at Urbana-Champaign l30l West Green Street. Urbana. Illinois 61801 Ronnnr A. KrNsev. KeneN ANN SuIrn School of Chemical Sciences University of lllinois at Urbana-Champaign 505 South Mathews Avenue, Urbana, Illinois 61801 Donelo M. Hr,NoBnsoN Department of Geology University of lllinois at Urbana-Champaign 1301 West Green Street. Urbana. Illinois 61801 eNo Enrc OlorrBI-o School of Chemical Sciences University of Illinois at Urbana-Champaign 505 South Mathews Avenue. Urbana, Illinois 61801 Abstract We presentin this paperhigh-resolution solid-state magic-angle sample spinning sodium- 23,aluminum -27 , andsilicon-29 nuclear magnetic resonance (NMR) spectraof a varietyof plagioclaseand alkali feldsparsand feldsparglasses. The resultsshow that MASS NMR spectracontain a great deal of informationabout feldspar structures. In particular,we observethe following.(l) AUSiorder/disorder and exsolution effects in alkalifeldspars are readily observable.(2) To our presentlevel of understandingthe publishedstructure refinementsof anorthiteare not consistentwith the NMR of spectraof anorthite.(3) The spectraofthe intermediateplagioclases are interpretable in termsofe- and/-plagioclases, with much of the signalapparently coming from strainedsites between albiteJike and anorthite-likevolumes
    [Show full text]
  • Behavior of Alkali Feldspars:Crystallographic Properties and Characterizutionof Compositionand Al-Si Distribution
    American Mineralogist, Volume 71, pages 869-890, 1986 Behavior of alkali feldspars:Crystallographic properties and characterizutionof compositionand Al-Si distribution Guv L. Hons Department of Geology, Iafayette College,Easton, Pennsylvania 18042 Ansrnlcr Four new alkali feldspar ion-exchange series have been synthesized, three with topo- chemically monoclinic Al-Si distributions ranging from sanidine to relatively ordered or- thoclase,the other a microcline-low albite series.Parent materials for three serieshave previously been studied by single-crystaltechniques, so Al-Si distributions are well char- acterized.Unit-cell dimensions and volumes have been measuredfor all seriesmembers and, with data for a previously reported fifth series, have been analyzed as a function of both composition and Al-Si distribution. The a unit-cell dimension, cornmonly used as a measureof composition in alkali feld- spars, is affected to a small but significant extent by Al-Si distribution and also apparenfly doesnot vary linearly with composition, as has previously been assumed.Variation of the b and c unit-cell dimensions with composition is best analyzedseparately for triclinic and monoclinic parts of the topochemically monoclinic series.Furthermore, b is not a linear function of c, an assumption that until now has been made in using these dimensions to calculate Al-Si distributions in alkali feldspars. Variation of c with mole fraction KAlSirO8 (N*) is linear in both the triclinic and the monoclinic parts of the topochemically monoclinic alkali feldspar series, as well as in the potassicregion of the low albite-microcline series.In addition, Ac/AN* slopesare virtually constant for all series.This provides an ordering parameter, c*, which for alkali feldspars with No.
    [Show full text]
  • Production, Reserves, and Processing of Feldspar and Feldspathoid Rocks in the Czech Republic from 2005 to 2019—An Overview
    minerals Article Production, Reserves, and Processing of Feldspar and Feldspathoid Rocks in the Czech Republic from 2005 to 2019—An Overview Jan Zahradník 1,2 , Jakub Jirásek 3,*, Jaromír Starý 4 and Martin Sivek 2 1 LB MINERALS, s.r.o., Tovární 431, 330 12 Horní Bˇríza, Czech Republic; [email protected] 2 Department of Geological Engineering, Faculty of Mining and Geology, Vysoká Škola Báˇnská-Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava-Poruba, Czech Republic; [email protected] 3 Department of Geology, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic 4 Czech Geological Survey, Klárov 3, 118 21 Praha, Czech Republic; [email protected] * Correspondence: [email protected] Received: 5 July 2020; Accepted: 10 August 2020; Published: 17 August 2020 Abstract: This paper aims to characterize and interpret the trends in reserves, resources, and mine production of feldspar and feldspathoid rocks during 2005–2019 in the Czech Republic. With over 101 Mt of total resources and 22 Mt of reserves, feldspar belongs to the crucial industrial minerals of the Czech Republic. With annual outputs of approximately 400–450 kt of feldspars and 20–35 kt of feldspathoid rocks (nepheline syenite), the Czech Republic ranks among the top European and world feldspar producers. Most of the production comes from leucocratic granitoid rocks (key active deposit: Krásno-Vysoký Kámen), followed by sedimentary rocks (key active deposit: Halámky), and granitic pegmatites (key active deposit: Luženiˇcky).Nepheline syenite is mined at a single deposit. All deposits are extracted from open pits (quarries).
    [Show full text]
  • Open Research Online Oro.Open.Ac.Uk
    Open Research Online The Open University’s repository of research publications and other research outputs Geochemical Endmembers preserved in the fluviolacustrine sediments of Gale crater Conference or Workshop Item How to cite: Bedford, C. C.; Bridges, J. C.; Schwenzer, S. P.; Wiens, R. C.; Rampe, E. B.; Frydenvang, J. and Gasda, P. J. (2017). Geochemical Endmembers preserved in the fluviolacustrine sediments of Gale crater. In: Fourth International Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life, 2-6 Oct 2017, Flagstaff, Arizona, USA. For guidance on citations see FAQs. c [not recorded] Version: Not Set Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online’s data policy on reuse of materials please consult the policies page. oro.open.ac.uk GEOCHEMICAL ENDMEMBERS PRESERVED IN THE FLUVIOLACUSTRINE SEDIMENTS OF GALE CRATER. C. C. Bedford1, J. C. Bridges2, S. P. Schwenzer3, R. C. Wiens4, E. B. Rampe5, J. Frydenvang6, P. J. Gasda4. 1School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK (can- [email protected]), 2Leicester Institute for Space and Earth Observation, University of Leicester, UK. 3School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, UK. 4Los Alamos National Laboratory, Los Alamos, New Mexico, USA. 5NASA Johnson Space Centre, Houston, TX, US. 6Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark. Introduction: Gale crater possesses a diverse acquired per observation point and averaged to give the stratigraphic record consisting of conglomerate, fine to observation point compositions used in this study [9].
    [Show full text]
  • Geochemical Endmembers Preserved in the Fluviolacustrine Sediments of Gale Crater
    Fourth Conference on Early Mars 2017 (LPI Contrib. No. 2014) 3017.pdf GEOCHEMICAL ENDMEMBERS PRESERVED IN THE FLUVIOLACUSTRINE SEDIMENTS OF GALE CRATER. C. C. Bedford1, J. C. Bridges2, S. P. Schwenzer3, R. C. Wiens4, E. B. Rampe5, J. Frydenvang6, P. J. Gasda4. 1School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK (can- [email protected]), 2Leicester Institute for Space and Earth Observation, University of Leicester, UK. 3School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, UK. 4Los Alamos National Laboratory, Los Alamos, New Mexico, USA. 5NASA Johnson Space Centre, Houston, TX, US. 6Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark. Introduction: Gale crater possesses a diverse acquired per observation point and averaged to give the stratigraphic record consisting of conglomerate, fine to observation point compositions used in this study [9]. coarse sandstone and mudstone units deposited after ChemCam observation point analyses were classi- the crater’s formation (~3.8 Ga) in an ancient fluvio- fied according to sample morphology, stratigraphic lacustrine system [1–3]. Since landing in August 2012, position and grain size [11]. This study focuses on the NASA Mars Science Laboratory Curiosity rover points that have analysed in situ sedimentary outcrop in has analysed the geochemistry and mineralogy of these order to distinguish geochemical source characteristics. sedimentary units using the Chemistry and Camera Observation points identified to have hit obvious dia- (ChemCam), Alpha Particle X-ray Spectrometer genetic features (such as veins, nodules, raised ridges (APXS) and Chemistry and Mineralogy (CheMin and haloes), soil targets, float, pebbles, drill tailings XRD) onboard instrument suites.
    [Show full text]
  • Geochemistry of Hydrothermal Fluids from the PACMANUS, Northeast Pual and Vienna Woods Hydrothermal Fields, Manus Basin, Papua New Guinea Eoghan P
    Bridgewater State University Virtual Commons - Bridgewater State University Geological Sciences Faculty Publications Geological Sciences Department 2011 Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea Eoghan P. Reeves Jeffrey S. Seewald Peter Saccocia Bridgewater State University, [email protected] Wolfgang Bach Paul R. Craddock See next page for additional authors Follow this and additional works at: http://vc.bridgew.edu/geology_fac Part of the Earth Sciences Commons Virtual Commons Citation Reeves, Eoghan P.; Seewald, Jeffrey S.; Saccocia, Peter; Bach, Wolfgang; Craddock, Paul R.; Shanks, Wayne C. III; Sylva, Sean P.; Walsh, Emily; Pichler, Thomas; and Rosner, Martin (2011). Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea. In Geological Sciences Faculty Publications. Paper 9. Available at: http://vc.bridgew.edu/geology_fac/9 This item is available as part of Virtual Commons, the open-access institutional repository of Bridgewater State University, Bridgewater, Massachusetts. Authors Eoghan P. Reeves, Jeffrey S. Seewald, Peter Saccocia, Wolfgang Bach, Paul R. Craddock, Wayne C. Shanks III, Sean P. Sylva, Emily Walsh, Thomas Pichler, and Martin Rosner This article is available at Virtual Commons - Bridgewater State University: http://vc.bridgew.edu/geology_fac/9 Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 75 (2011) 1088–1123 www.elsevier.com/locate/gca Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea Eoghan P. Reeves a,b,⇑, Jeffrey S. Seewald b, Peter Saccocia c, Wolfgang Bach d, Paul R.
    [Show full text]
  • Chapter 5: Lunar Minerals
    5 LUNAR MINERALS James Papike, Lawrence Taylor, and Steven Simon The lunar rocks described in the next chapter are resources from lunar materials. For terrestrial unique to the Moon. Their special characteristics— resources, mechanical separation without further especially the complete lack of water, the common processing is rarely adequate to concentrate a presence of metallic iron, and the ratios of certain potential resource to high value (placer gold deposits trace chemical elements—make it easy to distinguish are a well-known exception). However, such them from terrestrial rocks. However, the minerals separation is an essential initial step in concentrating that make up lunar rocks are (with a few notable many economic materials and, as described later exceptions) minerals that are also found on Earth. (Chapter 11), mechanical separation could be Both lunar and terrestrial rocks are made up of important in obtaining lunar resources as well. minerals. A mineral is defined as a solid chemical A mineral may have a specific, virtually unvarying compound that (1) occurs naturally; (2) has a definite composition (e.g., quartz, SiO2), or the composition chemical composition that varies either not at all or may vary in a regular manner between two or more within a specific range; (3) has a definite ordered endmember components. Most lunar and terrestrial arrangement of atoms; and (4) can be mechanically minerals are of the latter type. An example is olivine, a separated from the other minerals in the rock. Glasses mineral whose composition varies between the are solids that may have compositions similar to compounds Mg2SiO4 and Fe2SiO4.
    [Show full text]
  • LWIR Spectroscopy on Feldspars from Rock Plugs for the Detection of Permeable Zones in Geothermal Systems
    LWIR spectroscopy on feldspars from rock plugs for the detection of permeable zones in geothermal systems. DOREEN NYAHUCHO July, 2020 SUPERVISORS: Dr. C.A, Hecker Dr. H.M.A, van der Werff LWIR spectroscopy on feldspars from rock plugs for the detection of permiable zones in geothermal systems. DOREEN NYAHUCHO Enschede, The Netherlands, July, 2020 Thesis submitted to the Faculty of Geo-Information Science and Earth Observation of the University of Twente in partial fulfilment of the requirements for the degree of Master of Science in Geo- information Science and Earth Observation. Specialization: Applied Remote Sensing for Earth Sciences SUPERVISORS: Dr. Chris Hecker Dr. Harald van der Werff THESIS ASSESSMENT BOARD: Prof. Cees van Westen (Chair) Dr. Martin Schodlok, BGR Germany (External Examiner) DISCLAIMER This document describes work undertaken as part of a programme of study at the Faculty of Geo-Information Science and Earth Observation of the University of Twente. All views and opinions expressed therein remain the sole responsibility of the author, and do not necessarily represent those of the Faculty. ABSTRACT Hydrothermal minerals indicate inferred permeability in geothermal systems besides being indicative of formation temperature, fluid composition and host rock composition. Minerals, particularly hydrothermal feldspars (adularia and albite), are important minerals in permeability studies. Adularia has a direct link to highly permeable zones, whereas albite is indicative of inferred low permeability. The ability to recognize and distinguish adularia from other feldspar minerals is, therefore, crucial. Spectroscopy has been used as an alternative approach relative to convectional methods to study feldspars minerals. However, there are limited spectroscopy studies on adularia, this study explores LWIR spectroscopy on rock plugs from the Karangahake epithermal Ag-Au system to map adularia and other associated minerals.
    [Show full text]
  • Deep High-Temperature Hydrothermal Circulation in a Detachment Faulting System on the Ultra-Slow Spreading Ridge ✉ ✉ Chunhui Tao1,2 , W.E
    ARTICLE https://doi.org/10.1038/s41467-020-15062-w OPEN Deep high-temperature hydrothermal circulation in a detachment faulting system on the ultra-slow spreading ridge ✉ ✉ Chunhui Tao1,2 , W.E. Seyfried Jr3 , R.P. Lowell4, Yunlong Liu 1,5, Jin Liang1, Zhikui Guo 1,6, Kang Ding7, Huatian Zhang8, Jia Liu 1, Lei Qiu1, Igor Egorov9, Shili Liao1, Minghui Zhao 10, Jianping Zhou1, Xianming Deng1, Huaiming Li1, Hanchuang Wang1, Wei Cai1, Guoyin Zhang1, Hongwei Zhou1, Jian Lin10,11 & Wei Li1 1234567890():,; Coupled magmatic and tectonic activity plays an important role in high-temperature hydrothermal circulation at mid-ocean ridges. The circulation patterns for such systems have been elucidated by microearthquakes and geochemical data over a broad spectrum of spreading rates, but such data have not been generally available for ultra-slow spreading ridges. Here we report new geophysical and fluid geochemical data for high-temperature active hydrothermal venting at Dragon Horn area (49.7°E) on the Southwest Indian Ridge. Twin detachment faults penetrating to the depth of 13 ± 2 km below the seafloor were identified based on the microearthquakes. The geochemical composition of the hydrothermal fluids suggests a long reaction path involving both mafic and ultramafic lithologies. Combined with numerical simulations, our results demonstrate that these hydrothermal fluids could circulate ~ 6 km deeper than the Moho boundary and to much greater depths than those at Trans-Atlantic Geotraverse and Logachev-1 hydrothermal fields on the Mid-Atlantic Ridge. 1 Key Laboratory of Submarine Geosciences, MNR, Second Institute of Oceanography, MNR, 310012 Hangzhou, China. 2 School of Oceanography, Shanghai Jiao Tong University, 200240 Shanghai, China.
    [Show full text]
  • Remote Raman Detection of Natural Rocks a Final
    REMOTE RAMAN DETECTION OF NATURAL ROCKS A FINAL REPORT SUBMITTED TO THE DEPARTMENT OF GEOLOGY AND GEOPHYSICS, UNIVERSITY OF HAWAI’I AT MĀNOA, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN GEOLOGY AND GEOPHYSICS August 2017 By Genesis Berlanga Advisor: Dr. Anupam K. Misra Remote Raman Detection of Natural Rocks 1,2* 1 1 GENESIS BERLANGA, TAYRO E. ACOSTA-MAEDA, SHIV K. SHARMA, JOHN N. 1 1 1,2 1 PORTER, PRZEMYSLAW DERA, HANNAH SHELTON, G. JEFFREY TAYLOR, 1 ANUPAM K. MISRA 1Hawai’i Institute of Geophysics and Planetology, University of Hawai’i, POST #602, 1680 East-West Road, Honolulu, Hawaii 96822, USA 2Department of Geology and Geophysics, University of Hawai’i, POST #702, 1680 East-West Road, Honolulu, Hawaii 96822, USA *Corresponding author: [email protected] Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX We report remote Raman spectra of natural igneous, metamorphic, and sedimentary rock samples at a standoff distance of 5 m. High quality remote Raman spectra of unprepared rocks are necessary for accurate and realistic analysis of future Raman measurements on planetary surfaces such as Mars. Our results display the ability of a portable Compact Remote Raman+LIBS+Fluorescence System (CRRLFS) to effectively detect and isolate various light and dark-colored mineral phases in natural rocks. The CRRLFS easily detected plagioclase and potassium feldspar end members, quartz, and calcite in rocks with high fluorescence backgrounds. Intermediate feldspars and quartz, when found in rocks with complex mineralogies, exhibited band shifts and broadening in the 504-510 cm-1 and 600-1200 cm-1 regions.
    [Show full text]
  • 04 Schrader Short Course Chapter
    Terrestrial and Lunar Geological Terminology Christian Schrader, MSFC/BAE Systems Introduction This section is largely a compilation of defining geological terms concepts. Broader topics, such as the ramifications for simulant design and in situ resource utilization, are included as necessary for context. Mineral Definition and overview A mineral is a naturally occurring inorganic substance with characteristic chemical composition and internal order. The internal order is the arrangement of atoms that make up a mineral’s crystal structure. The summary of major lunar minerals and their properties is shown in Appendix 1. Good sources for understanding the mineralogy of the Moon are The Lunar Sourcebook (ed. by Heiken et al, 1991), New Views of the Moon (ed. by Jolliff, et al., 2006), and Lunar Mineralogy (Frondel, 1975). Standard references for mineralogy in the context of geology and physical chemistry are Deere et al. (1992) and Gaines et al. (1997). The Moon is strongly depleted in volatile elements relative to the Earth. This is + manifested by a complete lack of known H2O- and OH -bearing minerals (e.g., clays and micas) and a paucity of Na-bearing minerals on the Moon. Conversely, there are few minerals on the Moon that do not occur on Earth, and those that are restricted to the Moon are generally related to terrestrial minerals; e.g., lunar armacolite is an extension of the terrestrial pseudobrookite mineral group (Frondel, 1975). However, the chemical compositions of lunar minerals may vary from their terrestrial counterparts. In addition to the relative depletion of volatiles, the lunar environment has a significantly lower oxygen 2+ fugacity (fO2) than that of the Earth.
    [Show full text]
  • 40Ar/39Ar Results for Alkali Feldspars Containing Diffusion Domains with Differing Activation Energy
    Gmchrm,ru c, (brnvnhimrcu 4clu Vol. 55. pp. 1435-1448 0016.7037/91/$3.00 + .X? Copyright Cm 1991 Pcrgamon Press pk. Printed m U.S.A. 40Ar/39Ar results for alkali feldspars containing diffusion domains with differing activation energy T. MARK HARRISON,’ OSCAR M. LOVERA,’ and MATTHEW T. HEIZLER~ ‘Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90024, USA ‘Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA 3Department of Earth and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90024. USA (Received June 29, 1990; accepted in revised form Fhwary 26, 1991) Abstract-Extension of the single diffusion domain/activation energy closure model of Dodson to apply to minerals with a discrete distribution of domain sizes appears to reconcile “0Ar/39Ar age spectra of alkali feldspars with their associated Arrhenius plots. However, small remaining discrepancies, particularly apparent in log (r/ro) plots, suggest that some, and perhaps most, alkali feldspars contain diffusion domains with activation energies that may vary by as much as 8 kcal/mol. An important consequence of even relatively small variations in activation energy between domains is that the shape of an age spectrum can change dramatically by varying the laboratory heating schedule. We find that Arrhenius and log (r/rO) plots have the potential to reveal even small differences in activation energy (-2 kcal/mol) between domains, at least in cases where the domains are well separated in size. Variations in activation energy of -5 kcal/mol can result in differences in calculated closure temperature of up to 30°C from that obtained assuming equal activation energies for all domains.
    [Show full text]