What Happens to a Rock During Subduction-Related Metamorphism?

Total Page：16

File Type：pdf, Size：1020Kb

What happens to a rock during subduction-related metamorphism? Assume the rock entering the subduction zone is a greenstone that has experienced prehnite-pumpellyite facies metamorphism (rock A). This rock will encounter increasing pressure and temperature as it is subducted changing first into a blueschist (rock B) and finally into eclogite (rock C). Answer the questions below to determine what happens to both the density of the rock and the H2O that is mineralogically bound in the rock. Mineral abundances in volume percent Minerals Greenstone Minerals Blueschist Minerals Eclogite Chlorite 30% Chlorite 25% Omphacite 45% Albite 25 Albite 25 Garnet 35 Illite 10 Phengite 10 Phengite 10 Prehnite 10 Lawsonite 15 Pumpellyite 15 Glaucophane 15 Calcite 10 Aragonite 10 Aragonite 10 1. Write the mineral formula for each mineral in the table below. Based on what you know about the minerals (chemistry, structure) attempt to list the silicate minerals in these rocks in order of increasing density. Minerals Idealized mineral formula Chlorite Albite Illite Prehnite Pumpellyite Calcite Phengite Lawsonite Glaucophane Aragonite Omphacite Garnet 2. Write the densities of each of the minerals in the table below. Please use units of g/cm3. For minerals that are solid solutions, use an average density. Minerals Density (g/cm3) Chlorite Albite Illite Prehnite Pumpellyite Calcite Phengite Lawsonite Glaucophane Aragonite Omphacite Garnet 3. Calculate the density of each rock using the volume percent minerals present and the density of those minerals. Greenstone _____________ Blueschist _____________ Eclogite _____________ 4. How does density change during progressive subduction zone metamorphism? 5. Generally speaking, what happens to the H2O content of the rocks during progressive subduction zone metamorphism? .

Copy Link

Recommended publications

Facies and Mafic
Metamorphic Facies and Metamorphosed Mafic Rocks l V.M. Goldschmidt (1911, 1912a), contact Metamorphic Facies and metamorphosed pelitic, calcareous, and Metamorphosed Mafic Rocks psammitic hornfelses in the Oslo region l Relatively simple mineral assemblages Reading: Winter Chapter 25. (< 6 major minerals) in the inner zones of the aureoles around granitoid intrusives l Equilibrium mineral assemblage related to Xbulk Metamorphic Facies Metamorphic Facies l Pentii Eskola (1914, 1915) Orijärvi, S. l Certain mineral pairs (e.g. anorthite + hypersthene) Finland were consistently present in rocks of appropriate l Rocks with K-feldspar + cordierite at Oslo composition, whereas the compositionally contained the compositionally equivalent pair equivalent pair (diopside + andalusite) was not biotite + muscovite at Orijärvi l If two alternative assemblages are X-equivalent, l Eskola: difference must reflect differing we must be able to relate them by a reaction physical conditions l In this case the reaction is simple: l Finnish rocks (more hydrous and lower MgSiO3 + CaAl2Si2O8 = CaMgSi2O6 + Al2SiO5 volume assemblage) equilibrated at lower En An Di Als temperatures and higher pressures than the Norwegian ones Metamorphic Facies Metamorphic Facies Oslo: Ksp + Cord l Eskola (1915) developed the concept of Orijärvi: Bi + Mu metamorphic facies: Reaction: “In any rock or metamorphic formation which has 2 KMg3AlSi 3O10(OH)2 + 6 KAl2AlSi 3O10(OH)2 + 15 SiO2 arrived at a chemical equilibrium through Bt Ms Qtz metamorphism at constant temperature and =
[Show full text]
Pumpellyite-(Al), a New Mineral from Bertrix, Belgian Ardennes
Eur. J. Mineral. 2007, 19, 247–253 Pumpellyite-(Al), a new mineral from Bertrix, Belgian Ardennes FRED´ ERIC´ HATERT1,*,MARCO PASERO 2,NATALE PERCHIAZZI2 and THOMAS THEYE3 1 LaboratoiredeMinéralogie, Département de Géologie, Bâtiment B18, UniversitédeLiège, 4000 Liège, Belgium * Corresponding author, e-mail: [email protected] 2 Dipartimento di Scienze della Terra, Università degli Studi di Pisa, Via S. Maria 53, 56126 Pisa, Italy 3 Institut für Mineralogie und Kristallchemie, Universität Stuttgart, Azenbergstraße 18, 70174 Stuttgart, Germany 2+ Abstract: Pumpellyite-(Al), ideally Ca2(Al,Fe ,Mg)Al2(SiO4)(Si2O7)(OH,O)2·H2O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates reaching 5 mm in diameter, constituted by acicular crystals associated with calcite, K-feldspar and chlorite. Pumpellyite-(Al) is transparent to translucent and exhibits an emerald-green to white colour, sometimes with bluish tinges. The lustre is vitreous and the streak is colourless. The mineral is non-fluorescent, brittle, and shows a perfect {100} cleavage. The estimated Mohs hardness is 5½, and the calculated density is 3.24 g/cm3. Pumpellyite-(Al) is biaxial positive, [ = 1.678(2), q = 1.680(2), * = 1.691(1) ( † = 590 nm), colourless in thin section, 2V = 46°, Y = b, no dispersion. Electron-microprobe analyses gave SiO2 37.52, Al2O3 25.63, MgO 1.99, FeO 4.97, MnO 0.11, CaO 23.21, BaO 0.01, Na2O 0.03, K2O 0.02, H2Ocalc. 6.71, total 100.20 wt. %. The resulting empirical formula, calculated on the basis of 2+ 8 cations, is (Ca1.99Na0.01) 7 2.00(Al0.42Fe 0.33Mg0.24Mn0.01) 7 1.00Al2.00(SiO4)(Si2O7)(OH)2.42 · 0.58H2O.
[Show full text]
Pdf/85/10/1623/3418147/I0016-7606-85-10-1623.Pdf by Guest on 30 September 2021 1624 D
Deformation and Metamorphism of the Franciscan Subduction Zone Complex Northwest of Pacheco Pass, California DARREL S. COWAN* Shell Oil Company, P.O. Box 527, Houston, Texas 77001 ABSTRACT juxtapose rock units that bear no apparent tion and metamorphism, along a major stratigraphie, deformational, or metamor- fault system of regional extent that is an The Franciscan Complex northwest of phic relation to one another. The structural important crustal expression of lithospheric Pacheco Pass, California, includes three units were separately deformed ' and consumption at depth. fault-bounded units, each characterized by metamorphosed under a variety of condi- Miyashiro (1961) suggested that the a different deformational style and suite of tions prior to their tectonic juxtaposition Franciscan and grossly parallel Sierra metamorphic mineral assemblages. Struc- during late Mesozoic continental margin Nevada batholith and related high- turally highest is jadeitic pyroxene-bearing subduction. Field and pétrographie evi- temperature, low-pressure metamorphic metagraywacke semischist. The areally ex- dence permit, but do not prove, the rocks are part of a series of circum-Pacific tensive Garzas tectonic mélange separates hypothesis that both the semischist and paired metamorphic belts. As such, they are the semischist from the structurally lowest exotic, high-grade mélange inclusions once in essence late Mesozoic analogs of rock as- pumpellyite-bearing Orestimba meta- were more deeply buried and have been semblages forming in active subduction graywacke.
[Show full text]
Finding of Prehnite-Pumpellyite Facies Metabasites from the Kurosegawa Belt in Yatsushiro Area, Kyushu, Japan
Journal ofPrehnite Mineralogical-pumpellyite and Petrological facies metabasites Sciences, in Yatsushiro Volume 107, area, page Kyushu 99─ 104, 2012 99 LETTER Finding of prehnite-pumpellyite facies metabasites from the Kurosegawa belt in Yatsushiro area, Kyushu, Japan * * ** Kenichiro KAMIMURA , Takao HIRAJIMA and Yoshiyuki FUJIMOTO *Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan ** Nittetsu-Kogyo Co., Ltd, 2-3-2 Marunouchi, Chiyoda, Tokyo 100-8377, Japan. Common occurrence of prehnite and pumpellyite is newly identified from metabasites of Tobiishi sub-unit in the Kurosegawa belt, Yatsushiro area, Kyushu, where Ueta (1961) had mapped as a greenschist facies area. Prehnite and pumpellyite are closely associated with chlorite, calcite and quartz, and they mainly occur in white colored veins or in amygdules in metabasites of the relevant area, but actinolite and epidote are rare in them. Pumpellyite is characterized by iron-rich composition (7.2-20.0 wt% as total iron as FeO) and its range almost overlaps with those in prehnite-pumpellyite facies metabasites of Ishizuka (1991). These facts suggest that the metabasites of the Tobiishi sub-unit suffered the prehnite-pumpellyite facies metamorphism, instead of the greenschist facies. Keywords: Prehnite-pumpellyite facies, Lawsonite-blueschist facies, Kurosegawa belt INTRODUCTION 1961; Kato et al., 1984; Maruyama et al., 1984; Tsujimori and Itaya, 1999; Tomiyoshi and Takasu, 2009). Until now, The subduction zone has an essential role for the global there is neither clear geological nor petrological evidence circulation of solid, fluid and volatile materials between suggesting what type of metamorphic rocks occupied the the surface and inside of the Earth at present.
[Show full text]
List of Abbreviations
List of Abbreviations Ab albite Cbz chabazite Fa fayalite Acm acmite Cc chalcocite Fac ferroactinolite Act actinolite Ccl chrysocolla Fcp ferrocarpholite Adr andradite Ccn cancrinite Fed ferroedenite Agt aegirine-augite Ccp chalcopyrite Flt fluorite Ak akermanite Cel celadonite Fo forsterite Alm almandine Cen clinoenstatite Fpa ferropargasite Aln allanite Cfs clinoferrosilite Fs ferrosilite ( ortho) Als aluminosilicate Chl chlorite Fst fassite Am amphibole Chn chondrodite Fts ferrotscher- An anorthite Chr chromite makite And andalusite Chu clinohumite Gbs gibbsite Anh anhydrite Cld chloritoid Ged gedrite Ank ankerite Cls celestite Gh gehlenite Anl analcite Cp carpholite Gln glaucophane Ann annite Cpx Ca clinopyroxene Glt glauconite Ant anatase Crd cordierite Gn galena Ap apatite ern carnegieite Gp gypsum Apo apophyllite Crn corundum Gr graphite Apy arsenopyrite Crs cristroballite Grs grossular Arf arfvedsonite Cs coesite Grt garnet Arg aragonite Cst cassiterite Gru grunerite Atg antigorite Ctl chrysotile Gt goethite Ath anthophyllite Cum cummingtonite Hbl hornblende Aug augite Cv covellite He hercynite Ax axinite Czo clinozoisite Hd hedenbergite Bhm boehmite Dg diginite Hem hematite Bn bornite Di diopside Hl halite Brc brucite Dia diamond Hs hastingsite Brk brookite Dol dolomite Hu humite Brl beryl Drv dravite Hul heulandite Brt barite Dsp diaspore Hyn haiiyne Bst bustamite Eck eckermannite Ill illite Bt biotite Ed edenite Ilm ilmenite Cal calcite Elb elbaite Jd jadeite Cam Ca clinoamphi- En enstatite ( ortho) Jh johannsenite bole Ep epidote
[Show full text]
What We Know About Subduction Zones from the Metamorphic Rock Record
What we know about subduction zones from the metamorphic rock record Sarah Penniston-Dorland University of Maryland Subduction zones are complex We can learn a lot about processes occurring within active subduction zones by analysis of metamorphic rocks exhumed from ancient subduction zones Accreonary prism • Rocks are exhumed from a wide range of different parts of subduction zones. • Exhumed rocks from fossil subduction zones tell us about materials, conditions and processes within subduction zones • They provide complementary information to observations from active subduction systems Tatsumi, 2005 The subduction interface is more complex than we usually draw Mélange (Bebout, and Penniston-Dorland, 2015) Information from exhumed metamorphic rocks 1. Thermal structure The minerals in exhumed rocks of the subducted slab provide information about the thermal structure of subduction zones. 2. Fluids Metamorphism generates fluids. Fossil subduction zones preserve records of fluid-related processes. 3. Rheology and deformation Rocks from fossil subduction zones record deformation histories and provide information about the nature of the interface and the physical properties of rocks at the interface. 4. Geochemical cycling Metamorphism of the subducting slab plays a key role in the cycling of various elements through subduction zones. Thermal structure Equilibrium Thermodynamics provides the basis for estimating P-T conditions using mineral assemblages and compositions Systems act to minimize Gibbs Free Energy (chemical potential energy) Metamorphic facies and tectonic environment SubduconSubducon zone metamorphism zone metamorphism Regional metamorphism during collision Mid-ocean ridge metamorphism Contact metamorphism around plutons Determining P-T conditions from metamorphic rocks Assumption of chemical equilibrium Classic thermobarometry Based on equilibrium reactions for minerals in rocks, uses the compositions of those minerals and their thermodynamic properties e.g.
[Show full text]
Minerals Found in Michigan Listed by County
Michigan Minerals Listed by Mineral Name Based on MI DEQ GSD Bulletin 6 “Mineralogy of Michigan” Actinolite, Dickinson, Gogebic, Gratiot, and Anthonyite, Houghton County Marquette counties Anthophyllite, Dickinson, and Marquette counties Aegirinaugite, Marquette County Antigorite, Dickinson, and Marquette counties Aegirine, Marquette County Apatite, Baraga, Dickinson, Houghton, Iron, Albite, Dickinson, Gratiot, Houghton, Keweenaw, Kalkaska, Keweenaw, Marquette, and Monroe and Marquette counties counties Algodonite, Baraga, Houghton, Keweenaw, and Aphrosiderite, Gogebic, Iron, and Marquette Ontonagon counties counties Allanite, Gogebic, Iron, and Marquette counties Apophyllite, Houghton, and Keweenaw counties Almandite, Dickinson, Keweenaw, and Marquette Aragonite, Gogebic, Iron, Jackson, Marquette, and counties Monroe counties Alunite, Iron County Arsenopyrite, Marquette, and Menominee counties Analcite, Houghton, Keweenaw, and Ontonagon counties Atacamite, Houghton, Keweenaw, and Ontonagon counties Anatase, Gratiot, Houghton, Keweenaw, Marquette, and Ontonagon counties Augite, Dickinson, Genesee, Gratiot, Houghton, Iron, Keweenaw, Marquette, and Ontonagon counties Andalusite, Iron, and Marquette counties Awarurite, Marquette County Andesine, Keweenaw County Axinite, Gogebic, and Marquette counties Andradite, Dickinson County Azurite, Dickinson, Keweenaw, Marquette, and Anglesite, Marquette County Ontonagon counties Anhydrite, Bay, Berrien, Gratiot, Houghton, Babingtonite, Keweenaw County Isabella, Kalamazoo, Kent, Keweenaw, Macomb, Manistee,
[Show full text]
Chromium Members of the Pumpellyite Group: Shuiskite-(Cr), Ca2crcr2[Sio4][Si2o6(OH)](OH)2O, a New Mineral, and Shuiskite-(Mg), a New Species Name for Shuiskite
minerals Article Chromium Members of the Pumpellyite Group: Shuiskite-(Cr), Ca2CrCr2[SiO4][Si2O6(OH)](OH)2O, a New Mineral, and Shuiskite-(Mg), a New Species Name for Shuiskite Inna Lykova 1,*, Dmitry Varlamov 2 , Nikita Chukanov 3, Igor Pekov 4, Dmitry Belakovskiy 5 , 6, 4 7 Oleg Ivanov y, Natalia Zubkova and Sergey Britvin 1 Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, ON K1P 6P4, Canada 2 Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Moscow Oblast 142432, Russia; [email protected] 3 Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Oblast 142432, Russia; [email protected] 4 Faculty of Geology, Moscow State University, Vorobyovy Gory, Moscow 119991, Russia; [email protected] (I.P.); [email protected] (N.Z.) 5 Fersman Mineralogical Museum, Russian Academy of Sciences, Leninsky Prospekt 18-2, Moscow 119071, Russia; [email protected] 6 Zavaritsky Institute of Mineralogy and Geochemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620016, Russia; [email protected] 7 Department of Crystallography, Institute of Earth Sciences, St. Petersburg State University, University Emb. 7/9, St. Petersburg 199034, Russia; [email protected] * Correspondence: [email protected] Deceased 01 February 2020. y Received: 7 April 2020; Accepted: 23 April 2020; Published: 26 April 2020 Abstract: A new pumpellyite-group mineral shuiskite-(Cr), ideally Ca2CrCr2[SiO4][Si2O6(OH)] (OH)2O, was found at the Rudnaya mine, Glavnoe Saranovskoe deposit, Middle Urals, Russia. It occurs on the walls of 0.5 to 1 cm thick fractures in chromitite, ﬁlled with calcite, Cr-bearing clinochlore, and uvarovite.
[Show full text]
Identification Tables for Common Minerals in Thin Section
Identification Tables for Common Minerals in Thin Section These tables provide a concise summary of the properties of a range of common minerals. Within the tables, minerals are arranged by colour so as to help with identification. If a mineral commonly has a range of colours, it will appear once for each colour. To identify an unknown mineral, start by answering the following questions: (1) What colour is the mineral? (2) What is the relief of the mineral? (3) Do you think you are looking at an igneous, metamorphic or sedimentary rock? Go to the chart, and scan the properties. Within each colour group, minerals are arranged in order of increasing refractive index (which more or less corresponds to relief). This should at once limit you to only a few minerals. By looking at the chart, see which properties might help you distinguish between the possibilities. Then, look at the mineral again, and check these further details. Notes: (i) Name: names listed here may be strict mineral names (e.g., andalusite), or group names (e.g., chlorite), or distinctive variety names (e.g., titanian augite). These tables contain a personal selection of some of the more common minerals. Remember that there are nearly 4000 minerals, although 95% of these are rare or very rare. The minerals in here probably make up 95% of medium and coarse-grained rocks in the crust. (ii) IMS: this gives a simple assessment of whether the mineral is common in igneous (I), metamorphic (M) or sedimentary (S) rocks. These are not infallible guides - in particular many igneous and metamorphic minerals can occur occasionally in sediments.
[Show full text]
Prehnite-Pumpellyite Facies Metamorphism
Andean Geology 37 (1): 54-77. January, 2010 Andean Geology formerly Revista Geológica de Chile www.scielo.cl/andgeol.htm Prehnite-pumpellyite facies metamorphism in the Cenozoic Abanico Formation, Andes of central Chile (33º50'S): chemical and scale controls on mineral assemblages, reaction progress and the equilibrium state Marcia Muñoz1, Luis Aguirre1, Mario Vergara1, Alain Demant2, Francisco Fuentes3, Andrés Fock4 1 Departamento de Geología, Universidad de Chile, Casilla 13518, Correo 21, Santiago, Chile. [email protected]; [email protected]; [email protected] 2 Laboratoire de Pétrologie Magmatique Université Aix-Marseille III, 13397 Marseille Cedex 20, France. [email protected] 3 Los Acacios, Parcela 142-3, Paine, Chile. [email protected] 4 SQM Salar S.A., Aníbal Pinto 3228, Antofagasta, Chile. [email protected] ABSTRACT. In the El Volcán and Rodeo de los Bueyes areas, Andean Principal Cordillera (east of Santiago; 33º50'S), an Upper Oligocene-Lower Miocene volcanic series belonging to the Abanico Formation (Late Eocene-Early Miocene) is exposed. The rock successions outcropping in both areas, ca. 3,300 m total thickness, have been affected by very low-grade, non-deformative metamorphism in the prehnite-pumpellyite facies. This is represented by the widespread development of secondary mineral assemblages composed of epidote, mixed-layer chlorite-smectite, albite, quartz, white mica, and titanite. These mineral assemblages also contain pumpellyite, prehnite or prehnite+actinolite in a few samples. Chemical characteristics, such as low compositional variability of mixed-layer chlorite-smectite and actino- lite independent from the metadomain where these phases are hosted, along with a high proportion of chlorite layers in the former, suggest that these phases closely represent the whole rock effective bulk composition.
[Show full text]
Manganese-Rich Minerals of the Pumpellyite Group from The
American Mineralogist, Volume 76, pages241-245, 1991 Manganese-richminerals of the pumpellyite group from the Precambrian SausarGroup, India SoNrN,c,rH D.q.scur.rlo SlN.lrn Crrarnnnonrr, Puu,x SnNcurrl., P. K. Bn,c.rrAcHARyA, H. Bmwnrnn, Surnrva Rov Department of Geological Sciences,Jadavpur University, Calcutta 700 032, India M. Furuoxr, Department of Earth and Planetary Sciences,Klushu University, Fukuoka, Japan Ansrucr Mn-rich minerals of the pumpellyite group are developed in Mn oxide ores of the Precambrian SausarGroup, India. The ores were intruded by late pegmatite dikes and calcite veins. A hydrothermal origin for thesephases through Ca-Mg-Fe-Al metasomatism is evident from their mode of occurrenceand textures. The phasesstudied show wide- spreadsubstitution between Mn3+ and Al in the l-site and between Mn2+ and Mg in the X-site. An Mg equivalent of okhotskite, reported for the first time, is present.This study establishesthat okhotskite representsthe Mn3+ end-member of the pumpellyite group of minerals and that solid solution between pumpellyite (Al dominant) and okhotskite is nearly complete. INrnonucrroN dition to pumpellyite, diverse Ca-Mg-Mn-Al-Na silicates piemontite Minerals with the pumpellyite structure having the such as tirodite, Mn-rich pyroxene, and have general formula (Ca,K,Na)r(Mn2+,A13+Mg,Fe,*)o(F€,*,-developed at the contact ofpegmatite dikes and the ores Al3*,Ti4*,Mn3*)8Si,2O56_,(OH),are named on the basis (Roy and Purkait, 1968).Samples of pumpellyite-bearing ofrelative concentration oftrivalent cations in their oc- rocks describedin this work were collected from a small tahedral sites. The phase is called pumpellyite if Al is outcrop of Mn ores at the contact of pegmatite dikes and dominant; ifFe3+ is dominant it is designatedas julgoldite calcite veins.
[Show full text]
Book Chapter
Book Chapter Stratabound ore deposits in the Andes : A review and a classification according to their geotectonic setting FONTBOTÉ, Lluís Reference FONTBOTÉ, Lluís. Stratabound ore deposits in the Andes : A review and a classification according to their geotectonic setting. In: Fontboté, L., Amstutz, G.C., Cardozo, M., Cedillo, E. & Frutos, J. Stratabound ore deposits in the Andes. Berlin : Springer, 1990. p. 815 p + map Available at: http://archive-ouverte.unige.ch/unige:77108 Disclaimer: layout of this document may differ from the published version. 1 / 1 Stratabound Ore Deposits in the Andes: A Review and a Classification According to Their Geotectonic Setting L. FONTBOTE 1 1 Introduction Systematic investigations of stratabound ore deposits in the Andes are relatively modern. Perhaps as a result of the very intensive Andean magmatic activity, it was not easy to break with the concept that most ore deposits are veins and replacement bodies related to late magmatic hydrothermal activity of some known or unknown intrusion. The role of the stratabound ore deposits was underestimated. As a conse quence, research on stratabound ore deposits was traditionally retarded with respect to other groups of ore deposits in the Andes, such as porphyry copper or hydrothermal vein deposits. Among the first works emphasizing the role of strata bound ore deposits in the Andes are those by Amstutz (1959, 1961), Entwistle and Gouin (1955), Kobe (1960), Ljunggren and Meyer (1964), and Ruiz et al. (1971). Stratabound ore deposits, including also some of the classic types known worldwide, such as volcanic-associated massive sulfide, Mississippi Valley-type, and red-bed type deposits, constitute, in fact, an important group in the Andes, also from the economic point of view.
[Show full text]