Conditions of Magma Generation for Archean Komatiites from the Barberton Mountainland, South Africa
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Mantle Peridotite Xenoliths
Earth and Planetary Science Letters 260 (2007) 37–55 www.elsevier.com/locate/epsl Mantle peridotite xenoliths in andesite lava at El Peñon, central Mexican Volcanic Belt: Isotopic and trace element evidence for melting and metasomatism in the mantle wedge beneath an active arc ⁎ Samuel B. Mukasa a, , Dawnika L. Blatter b, Alexandre V. Andronikov a a Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1005, USA b Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA Received 6 July 2006; received in revised form 3 May 2007; accepted 7 May 2007 Available online 13 May 2007 Editor: R.W. Carlson Abstract Peridotites in the mantle wedge and components added to them from the subducting slab are thought to be the source of most arc magmas. However, direct sampling of these materials, which provides a glimpse into the upper mantle beneath an active margin, is exceedingly rare. In the few arc localities where found, peridotite xenoliths are usually brought to the surface by basaltic magmas. Remarkably, the hornblende-bearing ultramafic xenoliths and clinopyroxene megaxenocrysts from El Peñon in the central Mexican Volcanic Belt were brought to the surface by a Quaternary high-Mg siliceous andesite, a rock type usually considered too evolved to be a direct product of mantle melting. The xenoliths and megaxenocrysts from El Peñon represent lithospheric mantle affected by significant subduction of oceanic lithosphere since as early as the Permian. Trace element and radiogenic isotope data we report here on these materials suggest a history of depletion by melt extraction, metasomatism involving a fluid phase, and finally, limited reaction between the ultramafic materials and the host andesite, probably during transport. -
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. -
Chapter 2 Alaska’S Igneous Rocks
Chapter 2 Alaska’s Igneous Rocks Resources • Alaska Department of Natural Resources, 2010, Division of Geological and Geophysical Surveys, Alaska Geologic Materials Center website, accessed May 27, 2010, at http://www.dggs.dnr.state.ak.us/?link=gmc_overview&menu_link=gmc. • Alaska Resource Education: Alaska Resource Education website, accessed February 22, 2011, at http://www.akresource.org/. • Barton, K.E., Howell, D.G., and Vigil, J.F., 2003, The North America tapestry of time and terrain: U.S. Geological Survey Geologic Investigations Series I-2781, 1 sheet. (Also available at http://pubs.usgs.gov/imap/i2781/.) • Danaher, Hugh, 2006, Mineral identification project website, accessed May 27, 2010, at http://www.fremontica.com/minerals/. • Digital Library for Earth System Education, [n.d.], Find a resource—Bowens reaction series: Digital Library for Earth System Education website, accessed June 10, 2010, at http://www.dlese.org/library/query.do?q=Bowens%20reaction%20series&s=0. • Edwards, L.E., and Pojeta, J., Jr., 1997, Fossils, rocks, and time: U.S. Geological Survey website. (Available at http://pubs.usgs.gov/gip/fossils/contents.html.) • Garden Buildings Direct, 2010, Rocks and minerals: Garden Buildings Direct website, accessed June 4, 2010, at http://www.gardenbuildingsdirect.co.uk/Article/rocks-and- minerals. • Illinois State Museum, 2003, Geology online–GeoGallery: Illinois State Museum Society database, accessed May 27, 2010 at http://geologyonline.museum.state.il.us/geogallery/. • Knecht, Elizebeth, designer, Pearson, R.W., and Hermans, Majorie, eds., 1998, Alaska in maps—A thematic atlas: Alaska Geographic Society, 100 p. Lillie, R.J., 2005, Parks and plates—The geology of our National parks, monuments, and seashores: New York, W.W. -
Geological Investigations in the Bird River Sill, Southeastern Manitoba (Part of NTS 52L5): Geology and Preliminary Geochemical Results by C.A
GS-19 Geological investigations in the Bird River Sill, southeastern Manitoba (part of NTS 52L5): geology and preliminary geochemical results by C.A. Mealin1 Mealin, C.A. 2006: Geological investigations in the Bird River Sill, southeastern Manitoba (part of NTS 52L5): geology and preliminary geochemical results; in Report of Activities 2006, Manitoba Science, Technology, Energy and Mines, Manitoba Geological Survey, p. 214–225. Summary and gravitational differentiation. In 2005, this study was initiated to examine the Bird Theyer (1985) identified unusual River Sill (BRS), a mafic-ultramafic layered intrusion cooling conditions requiring several magma pulses and located in the Bird River greenstone belt in southeastern cast doubt on a single magmatic intrusion theory. Manitoba. The BRS is currently an exploration target In 2005, this study was initiated to examine the for Ni-Cu–platinum group element (PGE) deposits and, controls on Ni-Cu-PGE mineralization and test the single in the past, hosted two Ni-Cu mines (Maskwa West and versus multiple injection hypothesis to establish the Dumbarton mines). relationship between mineralization and the magmatic Nickel-copper mineralization on the western half history. Specific objectives include of the BRS consists primarily of disseminated to blebby • detailed mapping of the Chrome, Page, Peterson pyrrhotite+chalcopyrite and is present in the ultramafic Block and National-Ledin properties (Figure GS-19-1); series of the Chrome and Page properties and the mafic • determination of the sulphur source for the Ni-Cu- series of the Wards property. During this study, several PGE mineralization; new sulphide-bearing localities in both the ultramafic and • delineation of the sill’s sulphur saturation history; mafic units of the sill have been identified. -
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) -
SPECTRAL CHARACTERIZATION of the ANCIENT SHERGOTTITES NORTHWEST AFRICA 7034 and 8159. KJ Orr1, LV Forman1, GK Benedix1
Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6177.pdf SPECTRAL CHARACTERIZATION OF THE ANCIENT SHERGOTTITES NORTHWEST AFRICA 7034 AND 8159. K. J. Orr1, L. V. Forman1, G. K. Benedix1, M. J. Hackett2, V. E. Hamilton3, and A. R. Santos. 1Space Science and Technology Centre (SSTC), School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia ([email protected]), 2School of Molecular and Life Sciences, Curtin University, Perth, Western Australia, Australia, 3Southwest Research Institute, 1050 Walnut St. #300, Boulder, CO 80302 USA. 4USRA, 7178 Columbia Gateway Dr., Columbia, MD 21046. Introduction: Thermal infrared (TIR) spectros- Ga), the oldest confirmed shergottites recovered so far copy is a powerful remote sensing tool used to unravel [5]. As the only shergottites of Early Amazonian to No- the surface compositions of a target body. This tech- achian in age, they provide an invaluable opportunity to nique has been widely used in space missions, because understanding Mars’ early history. of its ability to detect and determine modal mineralogy Methods: Both samples (~0.5g chips) were ac- of the surface geology. It has been instrumental in de- quired from UNM and were made into epoxy mounts. veloping our understanding of Mars, as the majority of NWA 8159 was analyzed with a Tescan Integrated Min- missions sent to Mars have included an infrared spec- eral Analyzer (TIMA) to determine modal mineral trometer. These spectrometers can operate either in the abundancies and produce high-resolution mineral maps. visible (VIS) to near-infrared (NIR) or in the mid-infra- NWA 8159 was also analyzed using EBSD to charac- red (MIR). -
Hydrated Peridotite – Basaltic Melt Interaction Part I: Planetary Felsic Crust Formation at Shallow Depth Anastassia Y
Hydrated Peridotite – Basaltic Melt Interaction Part I: Planetary Felsic Crust Formation at Shallow Depth Anastassia Y. BORISOVA1,2*, Nail R. ZAGRTDENOV1, Michael J. TOPLIS3, Wendy A. BOHRSON4, Anne NEDELEC1, Oleg G. SAFONOV2,5,6, Gleb S. POKROVSKI1, Georges CEULENEER1, Ilya N. BINDEMAN7, Oleg E. MELNIK8, Klaus Peter JOCHUM9, Brigitte STOLL9, Ulrike WEIS9, Andrew Y. BYCHKOV2, Andrey A. GURENKO10, Svyatoslav SHCHEKA11, Artem TEREHIN5, Vladimir M. POLUKEEV5, Dmitry A. VARLAMOV5, Kouassi E.A. CHARITEIRO1, Sophie GOUY1, Philippe de PARSEVAL1 1 Géosciences Environnement Toulouse, Université de Toulouse; UPS, CNRS, IRD, Toulouse, France 2 Geological Department, Lomonosov Moscow State University, Vorobievy Gory, 119899, Moscow, Russia 3 Institut de Recherche en Astrophysique et Planétologie (IRAP) UPS, CNRS, Toulouse, France 4 Central Washington University, Department of Geological Sciences, Ellensburg, WA 98926, USA 5 Korzhinskii Institute of Experimental Mineralogy, 142432, Chernogolovka, Moscow region, Russia 6 Department of Geology, University of Johannesburg PO Box 524, Auckland Park, 2006, Johannesburg, South Africa 7 Geological Sciences, University of Oregon, 1275 E 13th street, Eugene, OR, USA 8 Institute of Mechanics, Moscow State University, 1- Michurinskii prosp, 119192, Moscow, Russia 9 Climate Geochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, D-55020 Mainz, Germany 10 Centre de Recherches Pétrographiques et Géochimiques, UMR 7358, Université de Lorraine, 54501 Vandœuvre-lès-Nancy, France 11 Bavarian Research -
Depth and Degree of Melting of Komatiites
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 97, NO. B4, PAGES 4521-4540, APRIL 10, 1992 Depth and Degree of Melting of Komatiites CLAUDE HERZBERG Departmentof GeologicalSciences, Rutgers University,New Brunswick,New Jersey Mineral PhysicsInstitute, State Universityof New York, StonyBrook, New York High pressuremelting experimentsßhove ." v .......... new constraintsto be placedon the depthand degreeof partial melting of komatiites. Komatiitesfrom GorgonaIsland were formed by relatively low degreesof pseudoinvariantmelting(< 30 %)involving L + O1 + Opx + Cpx + Gt on the solidusat 40 kbar, about 130 km depth. Munro-typekomatiites were separatedfrom a harzburgiteresidue (L + O1 + Opx) at pressuresthat are poorly constrained,but were probablyaround 50 kbar, about 165 km depth;the degreeof partial melting was <40%. Komatiites from the BarbertonMountain Land were formed by high degrees(-50 %) of pseudoinvariantmelting (L + O1 + Gt + Cpx) of fertile mantleperidotitc in the 80- to 100-kbarrange, about 260- to 330- km depth. Secularvariations in the geochemistryof komatiitescould have formed in response to a reductionin the temperatureand pressureof meltingwith time. The 3.5 Ga Barbertonkomatiites and the 2.7 Ga Munro-typekomatiites could have formedin plumesthat were hotterthan the present-daymantle by 500ø and 30(Y',respectively. When excesstemperatures are this size, melting is deeperand volcanismchanges from basalticto komatiitic. The komatiitesfrom Gorgona Island, which are Mesozoic in age, may be representativeof komatiitesthat are predictedto occur in oceanicplateaus of Cretaceousage throughoutthe Pacific [Storey et al., 1991]. 1. INTRODUCTION range of CaO and A1203contents in the 80- to 160-kbar range. A calibration has been made of the effect of pressure on Komatiites are high MgO volcanic rocks that can be CaO/(CaO + A1203)and MgO in komatiiticliquids formed on roughly explained by high degrees of melting of mantle the solidus, and an examinationhas been made of the effect of peridotitc,typically 50 to 100 % [e.g., Vi.ljoenand Vi.ljoen, FeO. -
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. -
Complex Basalt-Mugearite Sill in Piton Des Neiges Volcano, Reunion
THE AMERICAN MINERALOGIST. VOL. 52, SEPTEMBER-OCTOBER, 1967 COMPLEX BASALT-MUGEARITE SILL IN PITON DES NEIGES VOLCANO, REUNION B. G. J. UetoN, Grant Institute oJ Geology,Uniaersi,ty oJ Ed.inburgh, Edinbwrgh, Scotland, AND W. J. WaoswoRru, Deportmentof Geology,The Un'it;ersity, Manchester,England.. ABsrRAcr An extensive suite of minor intrusions, contempcraneous with the late-stage differenti- ated lavas of Piton des Neiges volcano, occurs within an old agglomeratic complex. An 8-m sill within this suite is strongly difierentiated with a basaltic centre (Thorton Tuttle Index 27.6), residual veins of benmoreite (T. T. Index 75.2), and still more extreme veinlets of quartz trachyte. Although gravitative settling of olivine, augite and ore irz silzr is believed to be responsible for some of the observed variation, the over-all composition of the sill is con- siderably more basic than the mugearite which forms the chilled contacts. It is therefore concluded that considerable magmatic difierentiation must have preceded the emplacement of the sill. This probably took place in a dykeJike magma body with a compositional gra- dient from mugearite at the top to olivine basalt in the lower parts. INrnonucrroN The island of Reunion, in the western Indian Ocean, has the form of a volcanic doublet overlying a great volcanic complex rising from the deep ocean floor. The southeastern component of this doublet is still highly active and erupts relatively undifierentiated, olivine-rich basalts of mildly alkaline or transitional type (Coombs, 1963; Upton and Wads- worth, 1966). The northwestern volcano however has been inactive a sufficient time for erosionalprocesses to have hollowed out amphitheatre- headed valleys up to 2500 meters deep in the volcanic pile. -
Moore County Unbrecciated Cumulate Eucrite, 1.88Kg
Moore County Unbrecciated Cumulate Eucrite, 1.88 kg Seen to fall Figure 1a: The Moore County eucrite (fusion crust on left), from the collection of the North Carolina Museum of Natural Sciences. Scale from top to bottom of sample is ~ 5 cm. Photo courtesy of Chris Tacker. Introduction: The Moore County meteorite (Figures 1a,b,c) fell at 5:00 PM on April 21, 1913, on the farm of George C. Graves, located approximately three miles east of Carthage, Moore County, North Carolina (79o23’W, 35o25’N) (Henderson and Davis, 1936). A loud “rumbling and zooming” noise “with no distinct explosions” was first observed within a five or six mile radius of the fall, followed by a sighting of a red hot ball with a 15-foot trail of blue-black smoke; the meteorite itself landed within a few feet of a farmer, in a nearly-vertical (but slightly SW-sloping) hole in a freshly-plowed field (Henderson and Davis, 1936). Only one stone was recovered (Figure 1b), weighing approximately 1.88 kg (4 lbs. 2 oz.), with maximum dimensions approximately 15 cm x 10.5 cm x 8 cm (6 in x 4 3/16 in x 3 3/16 in) (Henderson and Davis, 1936). This stone was divided between the US National Museum (Smithsonian) in Washington, D.C., and the North Carolina State Museum in Raleigh, now the North Carolina Museum of Natural Sciences (Henderson and Davis, 1936), where the main fractions of the stone are still kept (0.9 kg at the USNM and ~0.56 kg at the NC Museum: Grady, 2000; Tacker, pers. -
The Investigated Rock Is One of the Gabbroic Bodies Which Crops out in the Surroundings of Lyngdal ( Extreme South of Norway)
PYROXENE RELATIONS IN A HYPERITE NEAR LYNGDAL, NORWAY JOHAN J. LAVREAU Lavreau, J. J.: Pyroxene relations in a hyperite near Lyngdal, Norway. Norsk Geologisk Tidsskrift, Vol. 50, pp. 333-340. Oslo 1970. Pyroxenes from a hyperite body associated with Precambrian gneisses were studied optically, chemically, and by means of X-rays. Pyroxene relations show that crystallization takes place at a temperature higher than the inversion of pigeonite, and proceeds into the stability field of hypersthene. The composition and the mutual relations between the pyroxenes suggest a crystallization process for these minerals. Johan J. Lavreau, Laboratoire de Mineralogie et Petrologie, Universite Libre de Bruxelles, Brussels, Belgium. Introduction The investigated rock is one of the gabbroic bodies which crops out in the surroundings of Lyngdal ( extreme South of Norway). It Iies 3 km north of the town, northwest of Skoland lake, and is crossed by the E 18 road to Flekkefjord (Fig. 1). It is a well defined and homogeneous crescent-shaped unit, about 1500 m long and 500 m broad. The rock is medium grained (1-2 mm grain size), dark grey in colour, and has a gabbro-dioritic compo sition (Niggli 1923, p. 126). Some dioritic varieties were also recognized (Table 1). The country rock is a monzonitic phenoblastic gneiss foliated parallel to the elongation of the hyperite body. The contacts are seldom visible, for the area is covered by recent deposits except in its northern part, where the rock is unfortunately tectonized and strongly retrometa morphosed. Experimental techniques Plagioclase and pyroxenes were first studied with the aid of the universal stage.