Tholeiitic 'Komatiite'−Basalt and Calc-Alkaline Andesite–Dacite
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The Mineralogy and Chemistry of the Anorogenic Tertiary Silicic Volcanics
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 86, NO. Bll, PAGES 10242-10256, NOVEMBER 10, 1981 The Mineralogyand Chemistryof the AnorogenicTertiary SilicicVolcanics of S.E. Queenslandand N.E. New South Wales, Australia A. EWART Departmentof Geology& Mineralogy,University of Queensland,St. Lucia,Brisbane, Queensland 4067 The Late Oligocene-EarlyMiocene volcanismof this regionis chemicallystrongly bimodal; the mafic lavas(volmetrically dominant) comprise basalts, hawaiites, and tholeiiticandesites, while the silicic eruptivesare mainly comendites,potassic trachytes, and potassic,high-silica rhyolites.The comendites and rhyoliteshave distinctivetrace element abundancepatterns, notably the extreme depletionsof Sr, Ba, Mg, Mn, P, Cr, V, and Eu, and the variable em'ichraentof suchelements as Rb, Zr, Pb, Nb, Zn, U, and Th. The trachytesexhibit thesecharacteristics to lesserdegrees. The comenditesare distinguished from the rhyolitesby their overall relative enrichmentof the more highly chargedcations (e.g., LREE, Nb, Y, and especiallyZr) and Zn. The phenocrystmineralogy of the trachytesand rhyolitescomprises various combinationsof the following phases:sodic plagioclase(albite-andesine), calcic anorthoclase, sanidine, quartz, ferroaugite-ferrohedenbergite,ferrohypersthene, fayalitic olivine, ilmenite, titano- magnetite,and rarely biotite (near annite) and Fe-hastingsiticamphibole. Accessories include apatite, zircon, chevkinite (ferrohedenbergite-bearingrhyolites only), and allanite (amphibole and botite rhyo- lites only). The comenditesgenerally contain -
Source to Surface Model of Monogenetic Volcanism: a Critical Review
Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 Source to surface model of monogenetic volcanism: a critical review I. E. M. SMITH1 &K.NE´ METH2* 1School of Environment, University of Auckland, Auckland, New Zealand 2Volcanic Risk Solutions, Massey University, Palmerston North 4442, New Zealand *Correspondence: [email protected] Abstract: Small-scale volcanic systems are the most widespread type of volcanism on Earth and occur in all of the main tectonic settings. Most commonly, these systems erupt basaltic magmas within a wide compositional range from strongly silica undersaturated to saturated and oversatu- rated; less commonly, the spectrum includes more siliceous compositions. Small-scale volcanic systems are commonly monogenetic in the sense that they are represented at the Earth’s surface by fields of small volcanoes, each the product of a temporally restricted eruption of a composition- ally distinct batch of magma, and this is in contrast to polygenetic systems characterized by rela- tively large edifices built by multiple eruptions over longer periods of time involving magmas with diverse origins. Eruption styles of small-scale volcanoes range from pyroclastic to effusive, and are strongly controlled by the relative influence of the characteristics of the magmatic system and the surface environment. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Small-scale basaltic magmatic systems characteris- hazards associated with eruptions, and this is tically occur at the Earth’s surface as fields of small particularly true where volcanic fields are in close monogenetic volcanoes. These volcanoes are the proximity to population centres. -
Module 7 Igneous Rocks IGNEOUS ROCKS
Module 7 Igneous Rocks IGNEOUS ROCKS ▪ Igneous Rocks form by crystallization of molten rock material IGNEOUS ROCKS ▪ Igneous Rocks form by crystallization of molten rock material ▪ Molten rock material below Earth’s surface is called magma ▪ Molten rock material erupted above Earth’s surface is called lava ▪ The name changes because the composition of the molten material changes as it is erupted due to escape of volatile gases Rocks Cycle Consolidation Crystallization Rock Forming Minerals 1200ºC Olivine High Ca-rich Pyroxene Ca-Na-rich Amphibole Intermediate Na-Ca-rich Continuous branch Continuous Discontinuous branch Discontinuous Biotite Na-rich Plagioclase feldspar of liquid increases liquid of 2 Temperature decreases Temperature SiO Low K-feldspar Muscovite Quartz 700ºC BOWEN’S REACTION SERIES Rock Forming Minerals Olivine Ca-rich Pyroxene Ca-Na-rich Amphibole Na-Ca-rich Continuous branch Continuous Discontinuous branch Discontinuous Biotite Na-rich Plagioclase feldspar K-feldspar Muscovite Quartz BOWEN’S REACTION SERIES Rock Forming Minerals High Temperature Mineral Suite Olivine • Isolated Tetrahedra Structure • Iron, magnesium, silicon, oxygen • Bowen’s Discontinuous Series Augite • Single Chain Structure (Pyroxene) • Iron, magnesium, calcium, silicon, aluminium, oxygen • Bowen’s Discontinuos Series Calcium Feldspar • Framework Silicate Structure (Plagioclase) • Calcium, silicon, aluminium, oxygen • Bowen’s Continuous Series Rock Forming Minerals Intermediate Temperature Mineral Suite Hornblende • Double Chain Structure (Amphibole) -
The Science Behind Volcanoes
The Science Behind Volcanoes A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from the magma chamber below the surface. Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust in the interiors of plates, e.g., in the East African Rift, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "Plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so- called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. Volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere or troposphere; however, they also absorb heat radiated up from the Earth, thereby warming the stratosphere. -
Geological Mapping, Structural Setting and Petrographic Description of the Archean Volcanic Rocks of Mnanka Area, North Mara
PROCEEDINGS, 43rd Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 12-14, 2018 SGP-TR-213 Geological Mapping, Structural Setting and Petrographic Description of the Archean Volcanic Rocks of Mnanka Area, North Mara Ezra Kavana Acacia Mining PLc, North Mara Gold Mine, Department of Geology, P. O. Box 75864, Dar es Salaam, Tanzania Email: [email protected] Keywords: Musoma Mara Greenstone Belt, Mnanka volcanics, Archaean rocks and lithology ABSTRACT The Mnanka area is situated within the Musoma Mara Greenstone Belt, the area is near to Nyabigena, Gokona and Nyabirama gold mines. Mnanka area comprises of the sequence of predominant rhyolitic volcanic rocks, chert and metasediments. Gold mineralizations in Mnanka area is structure controlled and occur mainly as hydrothermal disseminated intrusion related deposits. Hence the predominant observed structures are joints and flow banding. Measurements from flow banding plotted on stereonets using win-TENSOR software has provided an estimate for the general strike of the area lying 070° to 100° dipping at an average range angle of 70° to 85° while data from joints plotted on stereonets suggest multiple deformation events one of which conforms to the East Africa Rift System (striking WSW-ENE, NNE-SSW and N-S). 1. INTRODUCTION This paper focuses on performing a systematic geological mapping and description of structures and rocks of the Mnanka area. The Mnanka area is located in the Mara region, Tarime district within the Musoma Mara Greenstone Belt. The gold at Mnanka is host ed by volcanic rocks that belong to the Musoma Mara Greenstone Belt (Figure 1). The Mnanka volcanics are found within the Kemambo group that comprises of the sequence of predominant rhyolitic volcanic rocks, chert and metasediments south of the Nyarwana fault. -
4/5/2010 1 EPS 101/271 Lecture 16: Dacite “Rhyolite” Source Region
4/5/2010 EPS 101/271 Lecture 16: Dacite “Rhyolite” Source Region Geodetic Markers and Accuracy of the GPS units we use Chronology: 1871 Department formed by Joseph LeConte 1887 Charles Palache graduates from Berkeley High and enters Cal as a Freshman, continues on in graduate school 1892 Andrew Lawson teaches the first “systematic field geology class in the US” using Berkeley Hills 1893 Charles Palache publishes the results of the first doctoral thesis in geology at UC: “The Soda Rhyolite North of Berkeley” UC Bulletin of the Dept. of Geology, v. 1, p. 61-72 1902 Lawson and Palache publish “The Berkeley Hills- A Detail of Coast Range Geology” Bulletin of the Dept. of Geology,v. 2, p. 349-450 1 4/5/2010 The start of our Berkeley Field Tradition Lawson ’s first fie ld c lass 1892 Strawberry Creek Stadium Missing the Rhyolite Tuffs Hayward Fault Claremont Canyon Lawson and Palache’s map of the Berkeley Hills Global vs Local control on lithology Recall the explanation of the Miocene stratigraphic sequence Global climatic change Sudden global cooling FtiflFormation of polar ice caps Marine Regression causing the litho-sequence 2 4/5/2010 Rhyolites and Basalts Dacites SiO2 (Silica) 3 4/5/2010 Brimhall 2004 4 4/5/2010 Constraints on the Origin of Rhyolite Tuffs in the Berkeley/Oakland Hills Tecuya Formation in S CA Basalts Mixing lines as the result of ridge/trench collision Rhyolites Franciscan Initial Cole and Basu (1992) 5 4/5/2010 Source region for rhyolite magmas involves continental crust: Franciscan or its derivatives eg Orinda Rhyolite -
Chemical and Isotopic Studies of Monogenetic Volcanic Fields: Implications for Petrogenesis and Mantle Source Heterogeneity
MIAMI UNIVERSITY The Graduate School Certificate for Approving the Dissertation We hereby approve the Dissertation of Christine Rasoazanamparany Candidate for the Degree DOCTOR OF PHILOSOPHY ______________________________________ Elisabeth Widom, Director ______________________________________ William K. Hart, Reader ______________________________________ Mike R. Brudzinski, Reader ______________________________________ Marie-Noelle Guilbaud, Reader ______________________________________ Hong Wang, Graduate School Representative ABSTRACT CHEMICAL AND ISOTOPIC STUDIES OF MONOGENETIC VOLCANIC FIELDS: IMPLICATIONS FOR PETROGENESIS AND MANTLE SOURCE HETEROGENEITY by Christine Rasoazanamparany The primary goal of this dissertation was to investigate the petrogenetic processes operating in young, monogenetic volcanic systems in diverse tectonic settings, through detailed field studies, elemental analysis, and Sr-Nd-Pb-Hf-Os-O isotopic compositions. The targeted study areas include the Lunar Crater Volcanic Field, Nevada, an area of relatively recent volcanism within the Basin and Range province; and the Michoacán and Sierra Chichinautzin Volcanic Fields in the Trans-Mexican Volcanic Belt, which are linked to modern subduction. In these studies, key questions include (1) the role of crustal assimilation vs. mantle source enrichment in producing chemical and isotopic heterogeneity in the eruptive products, (2) the origin of the mantle heterogeneity, and (3) the cause of spatial-temporal variability in the sources of magmatism. In all three studies it was shown that there is significant compositional variability within individual volcanoes and/or across the volcanic field that cannot be attributed to assimilation of crust during magmatic differentiation, but instead is attributed to mantle source heterogeneity. In the first study, which focused on the Lunar Crater Volcanic Field, it was further shown that the mantle heterogeneity is formed by ancient crustal recycling plus contribution from hydrous fluid related to subsequent subduction. -
Relationships Between Pre-Eruptive Conditions and Eruptive Styles of Phonolite-Trachyte Magmas Joan Andújar, Bruno Scaillet
Relationships between pre-eruptive conditions and eruptive styles of phonolite-trachyte magmas Joan Andújar, Bruno Scaillet To cite this version: Joan Andújar, Bruno Scaillet. Relationships between pre-eruptive conditions and eruptive styles of phonolite-trachyte magmas. Lithos, Elsevier, 2012, 152 (1), pp.122-131. 10.1016/j.lithos.2012.05.009. insu-00705854 HAL Id: insu-00705854 https://hal-insu.archives-ouvertes.fr/insu-00705854 Submitted on 10 Jul 2012 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. 1 Relationships between pre-eruptive conditions and eruptive styles of phonolite-trachyte magmas JOAN ANDÚJAR*,a AND BRUNO SCAILLETa a. CNRS/INSU-UNIVERSITÉ D’ORLÉANS-BRGM ; INSTITUT DES SCIENCES DE LA TERRE D’ORLEANS, UMR 6113 - 1A, RUE DE LA FÉRROLLERIE-45071 ORLEANS CEDEX 2 (FRANCE) * Corresponding author : Joan Andújar phone number : (+33) 2 38 25 53 87 Fax: (+33) 02 38 63 64 88 e-mail address: [email protected] Bruno Scaillet e-mail address: [email protected] KEY WORDS: Phase equilibria, phonolite, trachyte, experimental petrology, eruptive dynamic, explosive, effusive, andesite, rhyolite, melt viscosity, magma viscosity. 2 Abstract Phonolitic eruptions can erupt either effusively or explosively, and in some cases develop highly energetic events such as caldera-forming eruptions. -
Part 629 – Glossary of Landform and Geologic Terms
Title 430 – National Soil Survey Handbook Part 629 – Glossary of Landform and Geologic Terms Subpart A – General Information 629.0 Definition and Purpose This glossary provides the NCSS soil survey program, soil scientists, and natural resource specialists with landform, geologic, and related terms and their definitions to— (1) Improve soil landscape description with a standard, single source landform and geologic glossary. (2) Enhance geomorphic content and clarity of soil map unit descriptions by use of accurate, defined terms. (3) Establish consistent geomorphic term usage in soil science and the National Cooperative Soil Survey (NCSS). (4) Provide standard geomorphic definitions for databases and soil survey technical publications. (5) Train soil scientists and related professionals in soils as landscape and geomorphic entities. 629.1 Responsibilities This glossary serves as the official NCSS reference for landform, geologic, and related terms. The staff of the National Soil Survey Center, located in Lincoln, NE, is responsible for maintaining and updating this glossary. Soil Science Division staff and NCSS participants are encouraged to propose additions and changes to the glossary for use in pedon descriptions, soil map unit descriptions, and soil survey publications. The Glossary of Geology (GG, 2005) serves as a major source for many glossary terms. The American Geologic Institute (AGI) granted the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) permission (in letters dated September 11, 1985, and September 22, 1993) to use existing definitions. Sources of, and modifications to, original definitions are explained immediately below. 629.2 Definitions A. Reference Codes Sources from which definitions were taken, whole or in part, are identified by a code (e.g., GG) following each definition. -
Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses
Michigan Technological University Digital Commons @ Michigan Tech Dissertations, Master's Theses and Master's Reports 2016 Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses Jordan Lubbers Michigan Technological University, [email protected] Copyright 2016 Jordan Lubbers Recommended Citation Lubbers, Jordan, "Rhyolite and Trachyte Formation at Lake City Caldera: Insight from Quantitative Textural and Geochemical Analyses", Open Access Master's Thesis, Michigan Technological University, 2016. https://doi.org/10.37099/mtu.dc.etdr/99 Follow this and additional works at: https://digitalcommons.mtu.edu/etdr Part of the Geochemistry Commons, and the Geology Commons RHYOLITE AND TRACHYTE FORMATION AT LAKE CITY CALDERA: INSIGHT FROM QUANTITATIVE TEXTURAL AND GEOCHEMICAL ANALYSES By Jordan E. Lubbers A THESIS Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE In Geology MICHIGAN TECHNOLOGICAL UNIVERSITY 2016 © 2016 Jordan E. Lubbers This thesis has been approved in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE in Geology. Geological and Mining Engineering and Sciences ThesisDepartment Advisor: ofChad Deering Committee Member: Olivier Bachmann Committee Member: William Rose Department Chair: John Gierke Table of Contents Acknowledgements ................................................................................................................................................. 6 Abstract ...................................................................................................................................................................... -
GEOLOGIC MAP of the MOUNT ADAMS VOLCANIC FIELD, CASCADE RANGE of SOUTHERN WASHINGTON by Wes Hildreth and Judy Fierstein
U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP 1-2460 U.S. GEOLOGICAL SURVEY GEOLOGIC MAP OF THE MOUNT ADAMS VOLCANIC FIELD, CASCADE RANGE OF SOUTHERN WASHINGTON By Wes Hildreth and Judy Fierstein When I climbed Mount Adams {17-18 August 1945] about 1950 m (6400') most of the landscape is mantled I think I found the answer to the question of why men by dense forests and huckleberry thickets. Ten radial stake everything to reach these peaks, yet obtain no glaciers and the summit icecap today cover only about visible reward for their exhaustion... Man's greatest 2.5 percent (16 km2) of the cone, but in latest Pleis experience-the one that brings supreme exultation tocene time (25-11 ka) as much as 80 percent of Mount is spiritual, not physical. It is the catching of some Adams was under ice. The volcano is drained radially vision of the universe and translating it into a poem by numerous tributaries of the Klickitat, White Salmon, or work of art ... Lewis, and Cis pus Rivers (figs. 1, 2), all of which ulti William 0. Douglas mately flow into the Columbia. Most of Mount Adams and a vast area west of it are Of Men and Mountains administered by the U.S. Forest Service, which has long had the dual charge of protecting the Wilderness Area and of providing a network of logging roads almost INTRODUCTION everywhere else. The northeast quadrant of the moun One of the dominating peaks of the Pacific North tain, however, lies within a part of the Yakima Indian west, Mount Adams, stands astride the Cascade crest, Reservation that is open solely to enrolled members of towering 3 km above the surrounding valleys. -
Volcanoes a to Z
Mount St Helens National Volcanic Monument – Teacher’s Corner -Teacher Info. Gifford Pinchot National Forest USDA Forest Service Volcanoes A to Z – Bus Activity Time Requirement: all day Exhibit / Trail Used: all exhibits/trails visited Locations: all locations visited, review on the bus en route back to your school. This activity is to be completed throughout the day and between other activities. Students will make note of key words while reading exhibits, interpretive signs, or labels, or by hearing them from each other, their teacher, movies or rangers. Consider distributing on the bus and collecting on the bus. Goal: 1) The student will become familiar with terminology related to the study of volcanoes, geology, or the ecosystems that surround them. Objectives: 1) The student will listen attentively. 2) The student will recall and list vocabulary words for things and concepts encountered on a field trip to Mount St. Helens National Volcanic Monument. 3) The student will distinguish nouns from other parts of speech. WASHINGTON EALRS and OREGON BENCHMARK STANDARDS Washington Social Studies 2.0- The student understands the complex physical and human characteristics of places and regions. Geography 2.1- Describe the natural characteristics of places and regions. Science 4.2 Use writing and speaking skills to organize and express science ideas. a. Use science vocabulary appropriately in written explanations, conversations and verbal presentations. Oregon Science-CCG The Dynamic Earth- Understand the properties and limited availability of the materials which make up the Earth. BM1- Recognize physical differences in Earth materials. Language-CCG Select functional, precise, and descriptive words appropriate to audience and purpose.