DOCSLIB.ORG

Expedition 352 Summary 2 Background 8 Scientific Objectives M.K

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Expedition 352 Summary 2 Background 8 Scientific Objectives M.K Reagan, M.K., Pearce, J.A., Petronotis, K., and the Expedition 352 Scientists, 2015 Proceedings of the International Ocean Discovery Program Volume 352 publications.iodp.org doi:10.14379/iodp.proc.352.101.2015 Contents 1 1 Abstract Expedition 352 summary 2 Background 8 Scientific objectives M.K. Reagan, J.A. Pearce, K. Petronotis, R. Almeev, A.A. Avery, C. Carvallo, 9 Principal results T. Chapman, G.L. Christeson, E.C. Ferré, M. Godard, D.E. Heaton, 23 Preliminary scientific assessment M. Kirchenbaur, W. Kurz, S. Kutterolf, H.Y. Li, Y. Li, K. Michibayashi, S. Morgan, 31 References W.R. Nelson, J. Prytulak, M. Python, A.H.F. Robertson, J.G. Ryan, W.W. Sager, T. Sakuyama, J.W. Shervais, K. Shimizu, and S.A. Whattam2 Keywords: International Ocean Discovery Program, IODP, JOIDES Resolution, Expedition 352, Izu-Bonin-Mariana fore arc, Site U1439, Site U1440, Site U1441, Site U1442, subduction initiation, magma genesis, ophiolites, basalt, boninite, high-magnesium andesite, volcanic rocks, dikes, drill core Abstract primitive and have lower TiO2 concentrations upward. The pres- ence of dikes at the base of the sections at Sites U1439 and U1440 The objectives for International Ocean Discovery Program Ex- provides evidence that boninitic and FAB lavas are both underlain pedition 352 were to drill through the entire volcanic sequence of by their own conduit systems and, therefore, that FAB and boninite the Bonin fore arc to group lavas are likely offset more horizontally than vertically. We thus propose that seafloor spreading related to subduction initiation 1. Obtain a high-fidelity record of magmatic evolution during sub- migrated from east to west after subduction initiation and during duction initiation and early arc development, early arc development. Initial spreading was likely rapid, and an ax- 2. Test the hypothesis that fore-arc basalt lies beneath boninite ial magma chamber was present. Melting was largely decompres- and understand chemical gradients within these units and sional during this period, but subducted fluids affected some across the transition, melting. As subduction continued and spreading migrated to the 3. Use drilling results to understand how mantle melting processes west, the embryonic mantle wedge became more depleted and the evolve during and after subduction initiation, and influence of subducted constituents dramatically increased, causing 4. Test the hypothesis that the fore-arc lithosphere created during the oceanic crust to be boninitic rather than tholeiitic. The general subduction initiation is the birthplace of suprasubduction zone decrease in fractionation upward in the boninite holes reflects the ophiolites. eventual disappearance of persistent magma chambers, either be- Expedition 352 successfully cored 1.22 km of igneous basement cause spreading rate was decreasing with distance from the trench and 0.46 km of overlying sediment, providing diverse, stratigraphi- or because spreading was succeeded by off-axis magmatism trench- cally controlled suites of fore-arc basalt (FAB) and boninites related ward of the ridge. The extreme depletion of the sources for all boni- to seafloor spreading and earliest arc development. FAB and related nitic lavas was likely related to the incorporation of mantle residues rocks were recovered at the two deeper water sites (U1440 and from FAB generation. This mantle depletion continued during gen- U1441) and boninites and related rocks were recovered at the two eration of lower silica boninitic magmas, exhausting clinopyroxene sites (U1439 and U1442) drilled upslope to the west. FAB lavas and from the mantle such that the capping high-silica, low-titanium dikes are depleted in high–field strength trace elements such as Ti boninites were generated from harzburgite. and Zr relative to mid-ocean-ridge basalt but have relatively diverse Additional results of the cruise include recovery of Eocene to re- concentrations of trace elements because of variation in degrees of cent deep-sea sediment that records variation in sedimentation melting, and potentially, the amount of subducted fluids involved in rates with time resulting from variations in climate, the position of their genesis. FAB are relatively differentiated, and average degree the carbonate compensation depth, and local structural control. of differentiation increases with depth, which is consistent with Three phases of highly explosive volcanism (latest Pliocene to Pleis- crystal fractionation in a persistent magma chamber system beneath tocene, late Miocene to earliest Pliocene, and Oligocene) were iden- a spreading center. Holes U1439C and U1442A yielded entirely tified, represented by 132 graded air fall tephra layers. Structures boninite differentiation series lavas that generally become more found in the cores and reflected in seismic profiles show that this 1 Reagan, M.K., Pearce, J.A., Petronotis, K., Almeev, R., Avery, A.A., Carvallo, C., Chapman, T., Christeson, G.L., Ferré, E.C., Godard, M., Heaton, D.E., Kirchenbaur, M., Kurz, W., Kutterolf, S., Li, H.Y., Li, Y., Michibayashi, K., Morgan, S., Nelson, W.R., Prytulak, J., Python, M., Robertson, A.H.F., Ryan, J.G., Sager, W.W., Sakuyama, T., Shervais, J.W., Shimizu, K., and Whattam, S.A., 2015. Expedition 352 summary. In Reagan, M.K., Pearce, J.A., Petronotis, K., and the Expedition 352 Scientists, Izu-Bonin-Mariana Fore Arc. Proceedings of the International Ocean Dis- covery Program, 352: College Station, TX (International Ocean Discovery Program). http://dx.doi.org/10.14379/iodp.proc.352.101.2015 2 Expedition 352 Scientists’ addresses. MS 352-101: Published 29 September 2015 M.K. Reagan et al. Expedition 352 summary area had periods of normal, reverse, and strike-slip faulting. Finally, cent dredging and submersible studies have provided additional in- basement rock P-wave velocities were shown to be slower than formation. Consequently, we were able to predict the sequence of those observed during logging of normal ocean crust sites. magmas likely to characterize the drill site and its surrounding re- gion, which developed after subduction initiation and prior to es- Background tablishment of a stable magmatic arc to the west by the late Eocene. The physical evolution of the fore arc and its associated lavas re- Izu-Bonin-Mariana system flects the reorganization of mantle convection and slab-derived The Izu-Bonin-Mariana (IBM) system is the type locality for fluid flow in response to the changing behavior of the sinking Pa- studying oceanic crustal accretion immediately following subduc- cific plate. This evolution, from initial seafloor spreading and erup- tion initiation. It is sufficiently old that it carries a full record of the tion of mid-ocean-ridge basalt (MORB)-like tholeiites to eruption evolution of crustal accretion from the start of subduction to the of boninites to fixing of the magmatic arc ~150 km west of the start of normal arc volcanism and sufficiently young that the key trench (separated by a broad, dead fore arc), took 7–8 million years features have not been excessively disturbed by subsequent erosion (Ishizuka et al., 2011). The process is reflected in the succession of or deformation. Intraoceanic arcs are built on oceanic crust and are igneous rocks of the Bonin Ridge, which is described in greater de- sites of formation of juvenile continental crust (Rudnick, 1995; Tat- tail below and depicted in the time-space diagram (Figure F2). sumi and Stern, 2006). Most active intraoceanic arcs are located in the western Pacific. Among these, the IBM system stands out as a Early subduction-related volcanism natural scientific target. This predominantly submarine convergent Diving and dredging on the fore-arc slope east of the Bonin plate boundary is the result of ~52 My of subduction (Ishizuka et al., Ridge and south of Guam recovered basaltic rocks from strati- 2011; Reagan et al., 2013) of the Pacific plate beneath the eastern graphic levels below boninite. These basalts have chemical compo- margin of the Philippine Sea plate. Stretching for 2800 km from the sitions that are similar to those of normal MORB (N-MORB). Izu Peninsula, Japan, to Guam, USA, the IBM system (summarized However, they are not identical, and hence the term “fore-arc basalt in Stern et al., 2003) has been extensively surveyed and has become (FAB)” was coined by Reagan et al. (2010) to highlight their distinc- an important natural laboratory for International Ocean Discovery tive setting and to emphasize that, in detail, FAB is a different Program (IODP) expeditions (Figure F1) aimed at understanding magma type from MORB. Most of the reliable 40Ar/39Ar ages and U- subduction initiation, arc evolution, and continental crust forma- Pb zircon ages of FAB are identical within error in both locations tion. A scientific advantage of studying the IBM system is its broad and indicate that FAB magmatism occurred at ~51–52 Ma, preced- background of scientific investigation resulting from its designation ing boninite eruption by 2–4 million years (Ishizuka et al., 2011; as a focus site by the US National Science Foundation MARGINS- Reagan et al., 2013). Lavas with compositions transitional between Subduction Factory experiment and similar efforts in Japan. We FAB and boninites from DSDP Leg 60 Site 458 in the Mariana fore know when subduction and arc construction began at the IBM sys- arc were dated at 49 Ma (Cosca et al., 1998). FAB and related gab- tem, even if the precise paleogeography is controversial, and there is bros are thought to relate to the first magmas produced as the IBM a good time-space record of crustal development. subduction zone began to form (Reagan et al., 2010). Geochemical data show that FAB magmas have light rare earth Petrologic evolution element–depleted rare earth element (REE) patterns, indicating The petrologic evolution of early stage magmatism in the IBM derivation from a moderately depleted lherzolitic upper mantle, arc has been reconstructed mainly based on volcanic sections that similar to that responsible for generating MORB (Figure F3).
Load more

Recommended publications
  • Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon
    Portland State University PDXScholar Dissertations and Theses Dissertations and Theses Winter 2-24-2016 Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon Arron Richard Steiner Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Geology Commons, and the Volcanology Commons Let us know how access to this document benefits ou.y Recommended Citation Steiner, Arron Richard, "Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon" (2016). Dissertations and Theses. Paper 2712. https://doi.org/10.15760/etd.2708 This Dissertation is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Field Geology and Petrologic Investigation of the Strawberry Volcanics, Northeast Oregon by Arron Richard Steiner A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Sciences and Resources: Geology Dissertation Committee: Martin J. Streck, Chair Michael L. Cummings Jonathan Fink John A.Wolff Dirk Iwata-Reuyl Portland State University 2016 © 2015 Arron Richard Steiner i ABSTRACT The Strawberry Volcanics of Northeast Oregon are a group of geochemically related lavas with a diverse chemical range (basalt to rhyolite) that erupted between 16.2 and 12.5 Ma and co-erupted with the large, (~200,000 km3) Middle Miocene tholeiitic lavas of the Columbia River Basalt Group (CRBG), which erupted near and geographically surround the Strawberry Volcanics. The rhyolitic lavas of the Strawberry Volcanics produced the oldest 40Ar/39Ar ages measured in this study with ages ranging from 16.2 Ma to 14.6 Ma, and have an estimated total erupted volume of 100 km3.
    [Show full text]
  • Nonexplosive and Explosive Magma/Wet-Sediment Interaction
    Journal of Volcanology and Geothermal Research 181 (2009) 155–172 Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.elsevier.com/locate/jvolgeores Nonexplosive and explosive magma/wet-sediment interaction during emplacement of Eocene intrusions into Cretaceous to Eocene strata, Trans-Pecos igneous province, West Texas Kenneth S. Befus a,⁎, Richard E. Hanson a, Daniel P. Miggins b, John A. Breyer a, Arthur B. Busbey a a Department of Geology, Texas Christian University, Box 298830, Fort Worth, TX 76129, USA b U.S. Geological Survey, Denver Federal Center, Box 25046, Denver, CO 80225, USA article info abstract Article history: Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous Received 16 June 2008 (Maastrichtian) to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced Accepted 22 December 2008 an array of features recording both nonexplosive and explosive magma/wet-sediment interaction. Intrusive Available online 13 January 2009 complexes with 40Ar/39Ar dates of ~47–46 Ma consist of coherent basalt, peperite, and disrupted sediment. Two of the complexes cutting Cretaceous strata contain masses of conglomerate derived from Eocene fluvial Keywords: deposits that, at the onset of intrusive activity, would have been N400–500 m above the present level of phreatomagmatism peperite exposure. These intrusive complexes are inferred to be remnants of diatremes that fed maar volcanoes during diatreme an early stage of magmatism in this part of the Trans-Pecos province. Disrupted Cretaceous strata along Trans-Pecos Texas diatreme margins record collapse of conduit walls during and after subsurface phreatomagmatic explosions.
    [Show full text]
  • Icelandic Hyaloclastite Tuffs Petrophysical Properties, Alteration and Geochemical Mobility
    Icelandic Hyaloclastite Tuffs Petrophysical Properties, Alteration and Geochemical Mobility Hjalti Franzson Gudmundur H. Gudfinnsson Julia Frolova Helga M. Helgadóttir Bruce Pauly Anette K. Mortensen Sveinn P. Jakobsson Prepared for National Energy Authority and Reykjavík Energy ÍSOR-2011/064 ICELAND GEOSURVEY Reykjavík: Orkugardur, Grensásvegur 9, 108 Reykjavík, Iceland - Tel.: 528 1500 - Fax: 528 1699 Akureyri: Rangárvellir, P.O. Box 30, 602 Akureyri, Iceland - Tel.: 528 1500 - Fax: 528 1599 [email protected] - www.isor.is Report Project no.: 540105 Icelandic Hyaloclastite Tuffs Petrophysical Properties, Alteration and Geochemical Mobility Hjalti Franzson Gudmundur H. Gudfinnsson Julia Frolova Helga M. Helgadóttir Bruce Pauly Anette K. Mortensen Sveinn P. Jakobsson Prepared for National Energy Authority and Reykjavík Energy ÍSOR-2011/064 December 2011 Key page Report no. Date Distribution ÍSOR-2011/064 December 2011 Open Closed Report name / Main and subheadings Number of copies Icelandic Hyaloclastite Tuffs. Petrophysical Properties, Alteration 7 and Geochemical Mobility Number of pages 103 Authors Project manager Hjalti Franzson, Gudmundur H. Gudfinnsson, Julia Frolova, Hjalti Franzson Helga M. Helgadóttir, Bruce Pauly, Anette K. Mortensen and Sveinn P. Jakobsson Classification of report Project no. 540105 Prepared for National Energy Authority and Reykjavík Energy Cooperators Moscow University, University of California in Davis, Natural History Museum in Iceland Abstract This study attempts to define the properties of hyaloclastite formations which control their petrophysical characteristics during their progressive alteration. It is based on 140 tuffaceous cores from last glaciation to 2–3 m y. The water content shows a progressive increase with alteration to about 12%, which mainly is bound in the smectite and zeolite alteration minerals.
    [Show full text]
  • Deep Sea Drilling Project Initial Reports Volume 59
    37. THE GEOCHEMISTRY, MINERALOGY, AND PETROLOGY OF BASALTS FROM THE WEST PHILIPPINE AND PARECE VELA BASINS AND FROM THE PALAU-KYUSHU AND WEST MARIANA RIDGES, DEEP SEA DRILLING PROJECT LEG 59 David P. Mattey, Nicholas G. Marsh, and John Tarney,1 Department of Geological Sciences, University of Birmingham, Birmingham B15 2TT, England INTRODUCTION netic fabric of the Parece Vela Basin suggest a similar origin—the sundering of the Palau-Kyushu Ridge in the Legs 59 and 60 of the International Phase of Oceanic late Oligocene (Karig, 1975). The origin of the West Drilling (IPOD) were designed to study the nature and Philippine Basin is less clear, however, and the age and history of volcanism of the active Mariana arc, its cur- magnetic fabric of this basin remain controversial. Re- rently spreading inter-arc basin (the Mariana Trough), cent studies of rocks dredged from the Mariana Trough and the series of inactive basins and intervening ridges (Hart et al., 1972), the Lau Basin (Hawkins, 1976), and that lie to the west (Fig. 1). The older basins and ridges the Scotia Sea (Saunders and Tarney, 1979) all reveal were drilled during Leg 59 as the first part of a transect that these basins are floored by basalts geochemically of single-bit holes drilled in each major basin and ridge. similar to basalts erupted at mid-ocean ridges. The for- The eastern part of the transect—the technically active mation of active back-arc basins (e.g., the East Scotia region—was drilled during Leg 60. Sea, Barker 1970) in the Mariana Trough (Karig et al., The evolution of island-arc volcanos and magma 1978) is considered by many authors to be the result of genesis associated with lithospheric subduction remain seafloor spreading broadly similar to that associated some of the most complex petrologic problems con- with a mid-ocean ridge (e.g., Karig, 1971).
    [Show full text]
  • Petrography of the Island of Hawaii
    Petrography of the Island of Hawaii GEOLOGICAL SURVEY PROFESSIONAL PAPER 214-D Petrography of the Island of Hawaii By GORDON A. MACDONALD GEOLOGICAL SURVEY PROFESSIONAL PAPER 214-D A study of representative samples of rock types from every volcano on Hawaii by thin sections, mineral grains, and hand specimens. UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1949 UNITED STATES DEPARTMENT OF THE INTERIOR J. A. Krug, Secretary GEOLOGICAL SURVEY W. E: Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 35 cents (paper cover) CONTENTS Page Page Abstract.. __J1_____________________________________ 51 HualalaL ____---__-__-__-__--_---___-___- 75 Introduction. -_-------___-_-_______-_-_____________ 51 General geology._____________________ 75 Previous investigations._____________________________ 51 Hualalai volcanic series..____----_-_--_ 75 Principal rock types_______________________________ 53 Lavas-__________________________ 75 Basaltic rocks.-________________________________ 54 Gabbroic and ultrabasie" xenoliths— 76 Andesites._____________________________________ 54 Phreatic explosion debris._________ 76 Trachytes. _----------_______--_-_________-____. 56 Trachyte of Puu Waawaa.—______ 76 Mauna Loa________________________________________ 56 Chemical analyses.___________________ 77 General geology._______________________________ 56 Mauna Kea__--__-_________-_-_-_--__-_-- 78 Lavas of the Ninole volcanic series..._____________ 57 General geology._____________________
    [Show full text]
  • Basaltic Glasses from Iceland and the Deep Sea: Natural Analogues to Borosilicate Nuclear Waste-Form Glass
    Basaltic glasses from Iceland and the deep sea: Natural analogues to borosilicate nuclear waste-form glass. MicliMlJ.J«rcinovfc and Rodney C.Ewing D«c«mb«r,1987 BASALTIC OLACSBI FROM ICBLAHD AVD THE DB» SBA: ITOBAX. AMALOGUBf TO BOROflLICATB MUCL1AB WMT1-F0RM GLASS Michael J. J«rcinovic and Rodn«y C. Ewing D«c«mb«r, 1987 D«parta«nt of Geology Th« University of New Mexico Albuquerque, New Mexico USA 87131 11 list of Tables iv list of Figures vi Suenery xiii Abstract xvi 1 introduction 1 1.1 Alteration 6 1.1.1 Palagonitizaticn 6 1.1.2 Palagcnitizaticn Rates 9 1.1.3 Secondary Mineralization 13 1.2 Samples 21 1.2.1 Iceland 21 1.2.2 Dredge Sanples 26 1.2.3 Drill Core Samples 26 2 Techniques 29 2.1 Thin Section Preparation 29 2.2 Scanning Electron Microscopy 31 2.3 X-Ray Diffraction 31 2.4 Electron Microprobe Analysis 32 2.5 Analytical Electron Microscopy 34 3 Results 35 3.1 Icelani 35 3.1.1 General cements 35 3.1.2 Fresh Mater Alteration 36 3.1.2.1 Pleistocene Snhjiftrtnl Volcanic» 37 3.1.2.1.1 Palagonite 37 3.1.2.1.2 Cssentation 42 3.1.2.2 Tungufell 55 3.1.2.2.1 Palagcnite 55 3.1.2.2.2 Oawntation 68 3.1.3 Seawater Alteration 72 3.1.3.1 General Conomts 72 3.1.3.1.1 Palagcnite 76 3.1.3.1.2 Cementation , 92 11.' 3.2 EKedge Sau&m 107 3.2.1 ROagonite 107 3.2.2 OsasntiiHin 117 3.3 Erill Om Saaples 128 3.3.1 ffelagcnite 128 3.3.2 t 3.4 Analytical Electron Microscopy 144 3.4.1 Saaple Description 144 3.4.2 Analytical Ilectrcn Micxceoopy 147 3.4.2.1 OSMI 113521-69 147 3.4.2.2 UGM1 113715 153 3.4.3 conclusion* 156 4 Discussion 158 4.1 ROagonite 158 4.2 Secondary Mineral Authigenasis, Solution Concentrations, and Mass Balance 180 4.3 Alteration Rates 200 5 Conclusions 206 5.1 Corrosion Machanisn 206 5.2 Alteration Products 207 5.3 Mass Balance 209 5.4 Alteration Rates 210 Acknowledgements 212 213 iv Table 1.
    [Show full text]
  • Ocean Drilling Program Scientific Results Volume
    Larson, R. L., Lancelot, Y., et al., 1992 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 129 19. GEOCHEMISTRY AND PETROGENESIS OF JURASSIC OCEAN CRUST BASALTS, SITE 801l P. A. Floyd2 and P. R. Castillo3 ABSTRACT Middle Jurassic basaltic lavas obtained from Site 801 in the western Pacific Pigafetta Basin represent ocean crust from the oldest segment of the present-day Pacific Ocean. A composite 131m section shows the basement to be composed of an upper alkalic basalt sequence (about 157 Ma) with ocean island basalt chemical features and a lower tholeiitic basalt sequence (about 167 Ma) with typical normal-type mid-ocean ridge basalt features. The basalt sequences are separated by a quartz-cemented, yellow goethite hydrothermal deposit. Most basalts are altered to some degree and exhibit variable, low-grade smectite- celadonite-pyrite-carbonate-zeolite assemblages developed under a mainly hydrated anoxic environment. Oxidation is very minor, later in development than the hydration assemblages, and largely associated with the hydrothermal deposit. The tholeiitic normal-type mid-ocean ridge basalt has characteristically depleted incompatible element patterns and all compositions are encompassed by recent mid-ocean ridge basalt from the East Pacific Rise. Chemically, the normal-type mid-ocean ridge basalt is divided into a primitive plagioclase-olivine ± spinel phyric group (Mg* = 72-60) and an evolved (largely) aphyric group of olivine tholeiites (Mg* = 62-40). Both groups form a single comagmatic suite related via open-system fractionation of initial olivine-spinel followed by olivine-plagioclase-clinopyroxene. The alkalic ocean island basalt are largely aphyric and display enriched incompatible element abundances within both relatively primitive olivine-rich basalts and evolved olivine-poor hawaiites related via mafic fractionation.
    [Show full text]
  • Volcanic Rocks of the El Modeno Area Orange County California
    Volcanic Rocks of the El Modeno Area Orange County California GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-L Volcanic Rocks of the El Modeno Area Orange County California By ROBERT F. YERKES SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-L Description of extrusive pyroclastic and flow rocks of El Modeno volcanics of middle to late Miocene age UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957 UNITED STATES DEPARTMENT OF THE INTERIOR Fred A. Seaton, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 31.00 (paper cover) CONTENTS Page Descriptive geology—Continued Page Abstract_________________________________________ 313 Igneous rocks—Continued Introduction- ____________________________________ 313 Associated igneous rocks—Continued Previous investigations- _____________________________ 314 Tuffaceous material in La Vida member of Localities from which samples were obtained __________ 314 Puente formation,____________________ 322 Descriptive geology----_---_---____----__ _________ 316 Summary of petrography. __________________ 323 Igneous rocks _ ________________________________ 316 Sedimentary rocks, Cenozoic system. _ ____________ 324 Tuffs of the Topanga formation _ _____________ 316 Silverado formation_________________________ 324 El Modeno volcanics_ ______________________ 316 Santiago formation__________________________ 325 Basalt flow member..___________________ 316 Vaqueros and Sespe
    [Show full text]
  • Chlorophaeite, Sideromelane, and Palagonite from the Columbia River
    360 rHE AMER]CAN MINERALOGIST CHLOROPHAEITE,SIDEROMELANE AND PALAGONITE FROM THE COLUMBIA RIVER PLATEAU Mlnrrx A. Ppecocr* AND Rrcn.qnt E. Fur,r-rn, Uni'aersityof Washington CONTENTS Suuu.q.nv INrnoouctroN Cnlonopue.nrrB Occurrence Hand-specimen Microstudy Chemical composition The identity of chlorophaeite and certain materials described as palagonite Definition SroBnouBt-.tNe Occurrence Hand-specimen Microstudy Chemical composition The nomenclature of basic glasses Further occurrencesof sideromelane P.g.raGor.rtrB Petrographic descriptions The use of the term palagonite RrrpnBNcBs Explem.qtrox or Prern XII SUMMARY The three mineraloids, chlorophaeite, sideromelane and pala- gonite are characteristic of Kainozoic basaltic fields. From a new analysis of chlorophaeite from Oregon and existing analyses of materials from Scotland and India the approximate formula: (Fe,Al)zOg.2(\4g,Fe,Ca)O'4SiOr+10H2Ois derived. It is urged that the definition of chlorophaeite be extended to cover all hydrous, amorphous, pitch-like materials of deuteric origin, some of which have been named palagonite, in basalts and dolerites. An argument is advanced supporting the continued use of t Commonwealth Fund Fellow, at Harvard University from the University of Glaseow. JOURNAL MINERALOGICAL SOCIETY OF AMERICA 361 sideromelane, as distinct from tachylyte, as a specific name for ideal basaltic glass formed under conditions of specially rapid cooling. ft is shown that a chemical and genetic distinction exists between chlorophaeite and palagonite; and that palagonite should properly be restricted to its original significance, namely a gel produced essentially in the hydration of sideromelane by water or water vapor of exotic origin. INTRODUCTION The terms chlorophaeite, sideromelaneand palagonite were all proposed before the petrographic microscope was in common use, and consequently the original descriptions of these materials lack the precision now desirable.
    [Show full text]
  • Petrophysical Properties of Fresh to Mildly Altered Hyaloclasitie Tuffs
    Proceedings World Geothermal Congress 2005 Antalya, Turkey, 24-29 April 2005 Petrophysical Properties of Fresh to Mildly Altered Hyaloclasitie Tuffs Julia Frolova (1), Vladimir Ladygin (1), Hjalti Franzson (2) Omar Sigurðsson (2), Valgardur Stefánsson (3), and Vladimir Shustrov (4) (1) Moscow State University, Geological Department, Russia (2) Iceland GeoSurvey, 9 Grensásvegur, 108 Reykjavík, Iceland (3) National Energy Authority, 9 Grensásvegur, 108 Reykjavík, Iceland (4) JSC “Gazprom” Podzemgasprom Ltd, Moscow, Russia [email protected] Keywords: hyaloclastite, petrophysical properties, Iceland, these parameters has been ongoing in Iceland for the last palagonitization decade or so (e.g. Sigurdsson et al. 2000, Franzson et al. 2001) where petrophysical properties have been studied in ABSTRACT igneous rock samples of variable composition and hydrothermal alteration. This research project focuses on the In Iceland a significant part of reservoir rocks of cold and particular rocktype hyaloclastite commonly found in Iceland, thermal systems are basaltic hyaloclastite tuffs. and which is the source rock for significant part of the Hyaloclastites are dominantly formed in sub-glacial groundwaters in Iceland. The project is based on the eruptions. They are fragmental and glassy rocks as they are cooperation between Russian and Icelandic geoscientists as formed during a rapid magma quenching in the glacial melt indicated by the list of authors, and this paper describes the water. Hyaloclastites are highly permeable due to their first results mainly gathered by the former. clastic and very porous structure and should therefore be an important source rock for both thermal and fluid systems. It The paper first gives the environment of sampling and is known that the capacity and longevity of a reservoir is followed by a summary of the petrophysical and geological greatly controlled by the petrophysical properties of the host characteristics of the samples.
    [Show full text]
  • Sem-Tem Study of Icelandic Palagonite: Application to Hydrated Silicate Gel Interfaces in the Nakhlite Meteorites and Secondary Processes on Mars
    45th Lunar and Planetary Science Conference (2014) 2890.pdf SEM-TEM STUDY OF ICELANDIC PALAGONITE: APPLICATION TO HYDRATED SILICATE GEL INTERFACES IN THE NAKHLITE METEORITES AND SECONDARY PROCESSES ON MARS. C. C. Cockell1 H. G. Changela2, , C. Bryce1 and A. J Brearley2 1 University of Edinburgh, Edinburgh, EH9 3JZ 2University of New Mexico, Dept. Earth & Planetary Sciences, Albuquerque, NM87131, USA. UK . (Email:[email protected]) Introduction: Palagonite is a collective term for Results: The Icelandic Palagonite sample chemi- altered volcanic glass. Rapidly quenched volcanic cally displays 2 main phases from BSE and SEM-EDX glasses in a variety of environments ranging from hy- (Fig.1). The first is the primary glass phase - siderome- drothermal vents, sub marine and sub glacial environ- lane (Al,Ca,Mg,Fe) silicate with minor Na and Ti. The ments can form palagonite [1]. Palagonite typically second phase is texturally secondary to the glass. This contains an assemblage of primary basaltic glass that phase typically has lower Ca and Fe contents, lacks Na has been altered into amorphous hydrated silicate ‘gel- by qualitative SEM-EDX and resemble gel-palagonite palagonite’ and phyllosilicate (usually smectite) [1]. described in previous studies [1,5]. The samples also Although the nakhlite martian meteorites and their contain abundant sub mm sized pores containing either secondary alteration assemblages may have very dif- a ‘plated’ or ‘smooth’ texture. All of the pits analysed ferent petrogeneses to palagonite, the types of altera- were pores rather than vesicles due to their circular tion within them, namely the hydrated silicate assem- edges and pitted textures as seen when viewed at vari- blages (the most abundant form of alteration in the ous tilt angles with the FIB-SEM (Fig.
    [Show full text]
  • Durham E-Theses
    Durham E-Theses The volcanic geology of Vestur Skaftarfellssysla Iceland Robson, G. R. How to cite: Robson, G. R. (1956) The volcanic geology of Vestur Skaftarfellssysla Iceland, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/9238/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk THESIS presented in candidature for the degree of DOCTOR OP PHILOSOPHY of the University of Durham. The Volcanic Geology of Vestiir - Skaftarfellssysla Iceland. G.R. RolDSon. Being an account of the work carried out at the Geology Department, Durham University (Durham Division) During the period 1949 - 52 under the direc• tion of Professor L. R. Wager, F.R.S. (1949 - 50) and Professor K.C. Dunham, F.R.S. (1950 - 52). • SGIENCf CONTENTS. Page No. 1. PREFACE 1 2. INTRODUCTION 5 (a) The Geology of Iceland 5 ("b) The Region Studied 6 (c) The Geography of the Region 6 PART 1.
    [Show full text]