Seismological and Geochemical Evidence for Forearc Crust and Mantle Removed by Late Neogene Andean Forearc Subduction Erosion En

Total Page:16

File Type:pdf, Size:1020Kb

Seismological and Geochemical Evidence for Forearc Crust and Mantle Removed by Late Neogene Andean Forearc Subduction Erosion En Seismological and Geochemical Evidence for Forearc Crust and Mantle Removed by late Neogene Andean Forearc Subduction Erosion Entering the Mantle Wedge and the Andean Arc Magma Source Suzanne Mahlburg Kay*. Adam R. Goss, Patrick Mulcahy Dept. Earth Atm. Sci., INSTOC, Cornell Univ. Ithaca, NY, 14853, USA *Contact email: [email protected] Abstract. Forearc subduction erosion has been suggested Geochemical evidence for recycling of forearc crust in to be a major process in shaping the Andean margin from Neogene arc magmas has been suggested in regions where Colombia to Patagonia, yet questions remain as to how the frontal arc has migrated into the foreland, in particular much removed forearc lithosphere reaches the arc magma in the northern part of the Southern Volcanic Zone on the source and the backarc. Geochemical evidence for forearc southern margin of the Chilean-Pampean flat-slab where crust in Neogene magmas comes from the northern part of the SVZ where the arc front migrated ~ 35 km eastward at the arc front migrated ~ 35 km eastward at 19-16 Ma and 19-16 Ma and ~ 50 km at 7-4 Ma and the southernmost another ~ 50 km at 7-4 Ma (Kay et al., 2005). A similar CVZ (27°S to 28°S) where the frontal arc migrated ~ 40-50 case for a pulse of forearc subduction erosion has been km from 8 to 3 Ma over the developing bend in the made in the southernmost Central Volcanic Zone on the subducting Nazca plate on the northern boundary of the northern margin of the flat-slab at 27°S to 28°S where the flat-slab region. Here, the average calculated forearc loss frontal arc migrated ~ 40-50 km from 8 to 3 Ma (Kay and 3 is 164 km /my/km over 6 million years. A similar amount of Mpodozis, 2002; Goss and Kay, 2009; Kay et al., 2011). forearc subduction erosion can be inferred in the flat-slab During this time, mafic adakitic andesitic magmas (Pircas region where low Vp/Vs ratios (1.65-1.72) in the mantle Negras lavas) were erupted between the ~26 to 8 Ma wedge could be due to forearc lithosphere entering the Maricunga and < ~ 3 Ma Central Volcanic Zone arc fronts. wedge at 8-3 Ma at the time of most rapid shallowing of the flat-slab. A case for a current accelerated pulse of The region is over the subducting Nazca slab where forearc subduction erosion can also be made in the revised contours to the Wadati-Benioff zone from the southern NVZ where the Carnegie ridge is subducting and southern PUNA seismic deployment show the slab bending erupting magmas can have adakitic signatures. eastward to form the northern boundary of the modern Chilean (Pampean) flat-slab region (Mulcahy et al., 2010; Keywords: Forearc subduction erosion, flat-slab, Central Mulcahy, 2012). A restoration, assuming a constant 300 Andes, arc magmatism. km frontal arc to trench gap since the early Miocene, suggests an average forearc loss of 164 km 3/my/km over 6 million years (based on Goss et al., 2012) in this region. 1 Introduction North-south Vp tomographic profiles from the southern Forearc subduction erosion has been suggested to be a Puna seismic experiment (Bianchi et al., 2012) along the major process shaping the Andean margin from Colombia southern part of the Central Volcanic Zone volcanic arc to Patagonia (e.g., Clift and Hartley, 2007). Evidence for reveal a low velocity anomaly beneath the Ojos del Salado this process has largely come from the forearc, and volcano and a high velocity anomaly just to the north, questions remain as to how much of the removed forearc which is most likely related to the effects of the subducting crust and mantle lithosphere reaches the arc magma source slab. One explanation of the high velocity region is that it region and the wedge under the backarc, and ultimately reflects forearc crustal and mantle lithosphere built up how much is recycled into the mantle. This crustal and under the arc as a result of subduction erosion associated mantle lithosphere can potentially be tracked using both with the frontal arc migration in this region (Kay and geochemical and geophysical methods as shown below in Mpodozis, 2002; Goss et al., 2012). examples from the northern part of the Southern Volcanic Zone, the southernmost part of the Central Volcanic Zone, Geochemical evidence for subducted eroded forearc crust the Chilean (Pampean) flat-slab region and the southern entering the arc magma source in this region comes from: part of the Northern Volcanic Zone. (1) transient steep REE patterns in adakitic arc magmas, which are not attributable to slab melting nor to any simple model with in situ garnet-bearing lower crustal residues, 2 Late Neogene Subduction Erosion on the (2) elevated Mg, Cr and Ni contents consistent with partial Northern and Southern Margins of the melts of subducted eroded crust reacting with the mantle Chilean-Pampean Flat-slab Region wedge prior to interacting with the overlying crust, (3) a marked step in isotopic enrichment in similar age mafic to 215 silicic magmas at the time of arc migration, and (4) plate being too low to release a sufficient volatile flux to temporal isotopic changes in primitive basaltic magmas hydrate the overlying mantle wedge. with near mantle δ18 O ratios (Goss and Kay, 2009; Kay et al. 2011; Goss et al., 2012). These geochemical and 4 Active Forearc Subduction Erosion in the isotopic features contrast with those in magmatic rocks that Southern Part of the Northern Volcanic were erupted in the nearly stationary Neogene central Zone Andean arc front north of 25°S, where only slow subduction erosion rates are inferred (Clift and Hartley, 2007). A case for a current accelerated pulse of forearc subduction erosion can be made along the southern Columbian and northern Ecuadorian margin where the Carnegie ridge is 3 Late Neogene Subduction Erosion in the being subducted beneath the Andean margin, and erupting Chilean-Pampean Flat-slab Region Northern Volcanic Zone magmas can have adakitic signatures. In this region, a broadened volcanic arc is An amount of forearc subduction erosion similar to that present with centers located from 260 to 380 km east of the inferred for the regions just north of 28°S and south of trench over a shallowed subduction zone (e.g., Bourdon et 33°S where the frontal arc was translated some 40 to 50 al., 2003). Heated debate goes on over the role of slab km to the east can also be inferred for the intervening melting versus contamination of mantle derived magmas in amagmatic Chilean-Pampean flat-slab region, in which the thickened garnet-bearing lower crust in producing the late Oligocene to Miocene arc front is currently some 260 adakitic volcanic rocks of the Northern Volcanic Zone km east of the Chile trench. If magmatism was still active (e.g., Bryant et al., 2006; Samaniego et al. 2010; Chiaradia in the region of the current flat-slab, the volcanic arc et al. 2011) The debate centers around the questions as to joining the Central and Southern Volcanic zones would whether or not substantial slab melting can occur in this most likely extend through the prominent Calingasta- region, how crustal contamination of thickened lower crust Uspallata valley in Argentina, which is some 300 km from can be compatible with a restricted range of relatively the trench. Thus the amount of frontal arc migration would primitive isotopic compositions in lavas erupted through be ~ 40 km, essentially equivalent to that in the adjoining different types of crust, and why some adakitic lavas occur Central and Southern Volcanic Zones and the removed where the crust seems too thin to stabilize residual garnet amount of forearc crust and mantle would be similar. In (see discussion in Bryant et al., 2006; Samaniego et al., analogy with the forearc subduction erosion models to the 2005, 2010). north (e.g., Goss et al, 2012) and south (Kay et al. 2005), much of this material would have entered the mantle A little discussed alternative is that these adakitic wedge under the flat-slab in a major pulse of forearc signatures could, at least in part, be due to crust that has subduction erosion between 8-3 Ma, which coincides with been removed by forearc subduction erosion, entering the the inferred period of most rapid shallowing of the subduction channel and participating in the arc magma Chilean-Pampean flat-slab (e.g., Kay and Mpodozis, production process. Notably, the Cono La Virgin andesite 2002). The flat-slab geometry could play a role in and some ignimbrites of the Cayambe Volcanic Complex concentrating eroded forearc material in the mantle wedge in the main Ecuadorian arc in the Eastern Cordillera at ~0° under the flattest part of the subducting Nazca plate. latitude (Samaniego et al., 2005) have geochemical similarities to the Pircas Negras lavas and some of the An intriguing and related question in this region is the Jotabeche/Incapillo ignimbrites (Goss et al., 2011) that origin of the low Vp/Vs ratios (1.65-1.72) in the mantle have been associated with the pulse of forearc subduction wedge above the flat-slab (Wagner et al., 2006), which are erosion components in magmatic rocks in the attributed to a combination of low Vp and high Vs (~4.75) southernmost Central Volcanic Zone (Goss and Kay, 2009, seismic velocities. Wagner et al (2006) argue that these Goss et al., 2012). Forearc subduction erosion components low Vp/Vs ratio are best explained by the presence of in the magma source could likewise provide an explanation orthopyroxene in the mantle wedge, and Wagner et al.
Recommended publications
  • Gamonal S.Pdf
    Indice 1. Introducción …………………………………………………………………………. 6 1.1 Objetivos ………………………………………………………………...................... 7 1.2 Ubicación y accesos ..………………………………………………………………… 8 1.3 Clima y vegetación ………………………………………………………………….. 10 1.4 Metodología …………………………………………………………………………. 10 1.5 Historia de la propiedad y trabajos anteriores ……………………………………….. 11 2. Marco Geológico Regional ………………………………………………………...... 12 2.1 Basamento …………………………………………………………………………… 12 2.2 Volcanismo Cenozoico ……………………………………………………………… 14 2.3 Tectónica y estructuras ………………………………………………………………. 15 2.4 Alteración y mineralización ………………………………………………………… 18 3. Geología local ………………………………………………………………………… 19 3.1 Rocas estratificadas e intrusivas …………………………………………………….. 20 3.1.1 Formación Pantanoso (Pz) …………………………………………………...... 21 3.1.2 Lavas de Quebrada de Tapia (Kt) ……………………………………………… 21 3.1.3 Formación Astaburuaga (FAs) ………………………………………………… 21 3.1.4 Complejos de domos y depósitos volcánicos asociados (CDDV)………………. 23 3.1.4.1 Depósitos volcánicos y volcanoclásticos (CDv) …………………………… 23 3.1.4.2 Cuerpos Intrusivos (CDIn) ……………………………………………….. 24 3.1.4.3 Brechas freatomagmáticas (Bfm) ………………………………………… 25 3.1.5 Estratos de Sierra de la Sal (ESS) ……………………………………………… 26 3.1.6 Unidad Ignimbrítica I (UIg1) ………………………………………………….. 27 3.1.7 Unidad Tobácea (UTo) ………………………………………………………… 27 3.1.8 Unidad Andesítica Superior (UAS) …………………………………………… 28 3.1.9 Unidad Ignimbrítica II (UIg2) …………………………………………………. 29 3.2 Depósitos No consolidados ………………………………………………………… 29 3.2.1 Depósitos Aluviales de gravas
    [Show full text]
  • Muntean/Einaudi
    Economic Geology Vol. 95, 2000, pp. 1445–1472 Porphyry Gold Deposits of the Refugio District, Maricunga Belt, Northern Chile JOHN L. MUNTEAN†,* AND MARCO T. EINAUDI Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115 Abstract The porphyry gold deposits of the Refugio district and similar deposits in the Maricunga belt contain the lowest known copper to gold ratios (% Cu/ppm Au = ~0.03) of any porphyry-type deposit. The gold deposits are associated with subvolcanic andesitic to dacitic intrusions emplaced into coeval volcanic rocks. Both the Verde and Pancho deposits are zoned in space from a deeper zone of banded quartz veinlets associated with chlorite-magnetite-albite and/or pyrite-albite-clay alteration to a shallow zone of pyrite-albite-clay and local quartz-alunite ledges. Pancho contains an additional, deepest, porphyry copperlike zone, with quartz veinlets (A-veinlets) and potassic alteration. Relative to Verde, Pancho is telescoped, with all three zones present within a 400-m-vertical interval. The porphyry copperlike zone at Pancho is characterized by A-veinlets and pervasive potassic alteration, both restricted to intrusive rocks. A-veinlets range from hairline streaks of magnetite ± biotite with minor quartz and chalcopyrite, and K feldspar alteration envelopes to sugary quartz veinlets <1 cm in width with mag- netite and chalcopyrite and no alteration envelopes. Hypersaline liquid inclusions coexisting with vapor-rich in- clusions indicate temperatures above 600°C and salinities as high as 84 wt percent NaCl equiv. A pressure es- timate of 250 bars indicates a depth of 1,000 m, assuming lithostatic pressure.
    [Show full text]
  • Li in Plagioclase: Investigating Its Rapid Diffusion and Potential As
    Goldschmidt Conference Abstracts 2009 A181 Li in plagioclase: Investigating its Uranium minerals from a Portuguese rapid diffusion and potential as Variscan granite and its geospeedometer hydrothermal alteration 1,2 1 M.E.J.A. CABATO*, R. ALTHERR AND T. LUDWIG M.M.S. CABRAL PINTO , M.M.V.G. SILVA , 1 3 3 A.M.R. NEIVA , F. GUIMARÃES AND P.B. SILVA Mineralogie, Institut für Geowissenschaften, Universität- Heidelberg, Im Neuenheimer Feld 236, 69120 Heidelberg, 1Center of Geosciences, Department of Earth Sciences, Germany University of Coimbra, Portugal ([email protected]) (*correspondence: [email protected]) 2Department of Geosciences, University of Aveiro, Portugal 3LNEG–National Laboratory of Energy and Geology, 4466- Elemental and isotopic studies with Li as a geochemical 956 S. Mamede de Infesta, Portugal tracer for source components and potential tool for geospeedometry have proliferated in recent years. Indeed, the Electron microscopy images, X-ray maps and electron abundance and isotopic fractionation of Li, alongside its rather microprobe analyses were carried out on uraninite, coffinite, (meta)saleeite, thorite, xenotime, monazite and apatite from rapid diffusivity especially in plagioclase, remain topics of unaltered and altered Variscan peraluminous granite and interest and importance. In volcanic systems, such Li data may related hydrothermal brecciated uranium-quartz veins. demonstrate processes and timescales that lead up to the Uraninite occurs mainly in the unaltered granite [1], is rare in extrusion of magma. the altered granite and was not found in the mineralized quartz To further understand Li diffusion in (and out of) veins. Uraninite from the altered granite is fractured and plagioclase, we analyse exceptionally large crystals using the hydrated, has the radioactive damage halos filled with late SIMS, to be confirmed by other methods.
    [Show full text]
  • Nombre Entidad DOMICILIO COMUNA REGIÓN TRAMITACION Registro Public
    N° Fecha Fecha # ESTADO DE LA Regi N° Diario Nombre Entidad DOMICILIO COMUNA REGIÓN TRAMITACION Registro Public. stro MISION EVANGÉLICA PENTECOSTAL EL PEDRO URRIOLA N° 1290 - REGIÓN 1 TERMINADA 2 14-12-99 22-02-01 36895 CERRO NAVIA PESEBRE HUMILDE DE CRISTO CERRO NAVIA METROPOLITANA REGIÓN DEL BIO- 2 TERMINADA 4 15-06-00 13-10-00 36786 "CORPORACIÓN EVANGÉLICA ECO MUNDIAL" POBLA. LA ALBORADA, CALLE 2 Nº 29 CONCEPCION BIO SAN PABLO N.8223, BLOCK REGIÓN 3 TERMINADA 6 17-07-00 21-04-01 36943 APOSTOLES DE LOS ULTIMOS TIEMPOS SAN RAMÓN 44, DEPTO 201. LO PRADO METROPOLITANA AVDA. PEDRO DE VALDIVIA REGIÓN 4 TERMINADA 8 10-08-00 11-11-00 36810 IGLESIA EVANGÉLICA LUTERANA EN CHILE SANTIAGO Nº 3420, OF. 33 METROPOLITANA CALLE SCHUYLER Nº 77, REGIÓN DEL BIO- 5 TERMINADA 10 17-08-00 21-03-01 36918 IGLESIA EVANGÉLICA EPISCOPAL MISIONERA TALCAHUANO POBLA. PARTAL BIO CORPORACIÓN EVANGÉLICA "PLENITUD DE FRANCISCO DE ARANDA Nº REGIÓN 6 TERMINADA 13 22-08-00 14-05-01 36961 SAN BERNARDO CRISTO" 659 - A - SAN BERNARDO METROPOLITANA FERNANDO LAZCANO Nº REGIÓN 7 TERMINADA 14 22-08-00 22-01-01 36868 "IGLESIA EVANGÉLICA PENTECOSTAL" SAN MIGUEL 1298 - SAN MIGUEL METROPOLITANA CALLE GUAYANAS Nº 350, REGIÓN DE 8 TERMINADA 15 22-08-00 17-04-01 36939 IGLESIA EVANGÉLICA PENTECOSTAL DE CRISTO LOS ANDES POBLA. CENTENARIO VALPARAISO CALLE J. ZAMORE, JM. REGIÓN DE 9 TERMINADA 16 23-08-00 21-08-02 37339 IGLESIA EVANGELISTICA EL SEMBRADOR CARO Y PASAJE UNO N° 51, VALPARAISO VALPARAISO 1° SECTOR DE PLAYA ANCHA PASAJE SPICA 249 - REGIÓN 10 TERMINADA 21 11-09-00 20-01-10 39864 "UNIDOS EN CRISTO" PUDAHUEL PUDAHUEL METROPOLITANA POBL.
    [Show full text]
  • Geology of the Caspiche Porphyry Gold-Copper Deposit, Maricunga Belt, Northern Chile*
    ©2013 Society of Economic Geologists, Inc. Economic Geology, v. 108, pp. 585–604 Geology of the Caspiche Porphyry Gold-Copper Deposit, Maricunga Belt, Northern Chile* RICHARD H. SILLITOE,1,† JUSTIN TOLMAN,2,** AND GLEN VAN KERKVOORT3,*** 1 27 West Hill Park, Highgate Village, London N6 6ND, England 2 Exeter Resource Corporation, Suite 1660 - 999 W. Hastings St., Vancouver, BC V6C 2W2, Canada 3 Exeter Resource Corporation, Suite 701, 121 Walker St., North Sydney, NSW 2060, Australia Abstract The Caspiche porphyry gold-copper deposit, part of the Maricunga gold-silver-copper belt of northern Chile, was discovered in 2007 beneath postmineral cover by the third company to explore the property over a 21-year period. This company, Exeter Resource Corporation, has announced a proven and probable mineral reserve of 1,091 million tonnes (Mt) averaging 0.55 g/t Au, all but 124 Mt of which also contain 0.23% Cu, for a total of 19.3 Moz of contained gold and 2.1 Mt of copper. The deposit was formed in the latest Oligocene (~25 Ma) during the first of two volcanic and corre- sponding metallogenic epochs that define the Maricunga belt. The gold-copper mineralization is centered on a composite diorite to quartz diorite porphyry stock, within which five outward-younging phases are rou- tinely distinguished. The centrally located, early diorite porphyry (phase 1) hosts the highest-grade ore, av- eraging ~1 g/t Au and 0.4% Cu. The subsequent porphyry phases are quartz dioritic in composition and char- acterized by progressively lower gold and copper tenors. Stock emplacement was both pre- and postdated by the generation of large-volume, andesite-dominated breccias, with tuffaceous matrices, which are be- lieved to be shallow portions of diatremes.
    [Show full text]
  • (REFC) Magma Chambers: Implications for Differ
    Available online at www.sciencedirect.com ScienceDirect Geochimica et Cosmochimica Acta 143 (2014) 8–22 www.elsevier.com/locate/gca Modeling the compositional evolution of recharging, evacuating, and fractionating (REFC) magma chambers: Implications for differentiation of arc magmas Cin-Ty A. Lee a,⇑, Tien Chang Lee b, Chi-Tang Wu a a Dept. of Earth Science, MS-126 Rice University, 6100 Main St., Houston, TX 77005, United States b Dept. of Earth Sciences, University of California, Riverside, CA 92521, United States Available online 25 August 2013 Abstract Equations are presented to describe the compositional evolution of magma chambers undergoing simultaneous recharge (R), evacuation (E), and fractional crystallization (FC). Constant mass magma chambers undergoing REFC will eventually approach a steady state composition due to the “buffering” effect of recharging magma. Steady state composition is attained after 3/(Dax + ae) overturns of the magma chamber, where D is the bulk solid/melt partition coefficient for the element of interest and ax and ae are the proportions of crystallization and eruption/evacuation relative to the recharge rate. Steady state composition is given by Cre/(Dax + ae). For low evacuation rates, steady state concentration and the time to reach steady state scale inversely with D. Compatible (D > 1) elements reach steady state faster than incompatible (D < 1) elements. Thus, mag- ma chambers undergoing REFC will eventually evolve towards high incompatible element enrichments for a given depletion in a compatible element compared to magma chambers undergoing pure fractional crystallization. For example, REFC mag- ma chambers will evolve to high incompatible element concentrations for a given MgO content compared to fractional crys- tallization.
    [Show full text]
  • El Adoratorio Del Cerro El Potro: Arqueología De Alta Montaña En La Cordillera De Copiapó, Norte De Chile Ricardo Moyano1
    El adoratorio del cerro El Potro: Arqueología de alta montaña en la cordillera de Copiapó, norte de Chile Ricardo Moyano1 D INTRODUCCIÓN Ricardo Moyano1 Resumen En los Andes Meridionales se considera a las montañas Se exponen los resultados del reconocimiento arqueológico de las como lugares sagrados por estar vinculadas con los ante- nacientes del río Los Helados y del cerro El Potro, en el valle de Copia- pó. El objetivo principal fue constatar evidencias descritas para la zona pasados y espíritus tutelares, los fenómenos metereoló- que dieran cuenta de una huaca prehispánica, como también definir la gicos y las actividades agrícolas y ganaderas, las riquezas orientación orográfica de la arquitectura del centro metalúrgico Viña del inframundo, así como con la suerte y salud de las per- del Cerro. Los resultados sugieren que existieron prácticas culturales sonas (Martínez 1976, 1983; Reinhard 1983). vinculadas con la tradición andina de adorar a las montañas, que incluyeron ceremonias públicas en Viña del Cerro, así como ceremonias restringidas en el cerro El Potro y sus inmediaciones. Esta dualidad El Tawantinsuyo habría incorporado la costumbre de ado- habría permitido manejar las relaciones de poder y reciprocidad entre rar a las montañas a su religión estatal como parte de los incas y los grupos locales, así como formar parte de ritos anuales de su estrategia de dominación. Este proceso involucró la fertilidad, base de la cadena productiva minero-metalúrgica del valle del subordinación de la mano de obra local para construir río Copiapó. o mejorar los tambos, plataformas y caminos; la utiliza- Palabras claves: cerro El Potro – Viña del Cerro – Tawantinsuyo – Copiapó.
    [Show full text]
  • Geothermal Country Update for Ecuador, 2005 -2010
    Proceedings World Geothermal Congress 2010 Bali, Indonesia, 25-29 April 2010 Geothermal Country Update for Ecuador, 2005 -2010 Bernardo Beate, Rodney Salgado Escuela Politécnica Nacional, Dpto. de Geología, PO Box 17-01-2759, Quito/Ecuador [email protected] Keywords: Ecuador, geothermal exploration, heat sources, already completed the first geothermal gradient exploration hot springs of Ecuador, assessment of geothermal hole, ever, in Ecuador, on the Tufiño prospect, to a depth of prospects, use of geothermal energy. 554 m and final diameter NQ (76 mm). Chachimbiro has been allocated 1 MUSD for geophysical exploration ABSTRACT starting 2009 and reconnaissance geological and geochemical surveys are underway in Chacana-Papallacta Ecuador is located on the active convergent plate margin of prospect. This and several other high and low-medium Southamerica, which is characterized by a broad continental temperature geothermal prospects in Ecuador await state volcanic arc with abundant active volcanoes and intense and private investment to be developed in order to lessen seismicity. Earlier geothermal exploration, carried out from the dependance on fossil fuel use. Finally, in Ecuador, the mid 1970’s to the earlier 1990’s by government geothermal energy is challenged to be cost-efficient in front institutions with the aid of foreign technical assistance of an abundant hydro resource, as well as to be programs, defined a combined theoretical potential of about environmentally safe. 500 MWe for the three most promising geothermal prospects, namely: Tufiño-Chiles, Chalupas and Chachimbiro, located in the highlands of central-north 1. INTRODUCTION Ecuador. A dozen of other geothermal prospects, related to This paper is a follow up of the previous country update for silicic calderas, or to evolved stratovolcanoes, or even to the interval 2000-2005, published in the Proceedings of evolved basaltic shields, like Alcedo in Galapagos, will WGC2005 in Antalya, Turkey (Beate & Salgado, 2005).
    [Show full text]
  • The Central Atlantic Magmatic Province (CAMP) in Morocco
    The Central Atlantic Magmatic Province (CAMP) in Morocco Andrea Marzoli, Hervé Bertrand, Nasrrddine Youbi, Sara Callegaro, Renaud Merle, Laurie Reisberg, Massimo Chiaradia, Sarah Brownlee, Fred Jourdan, Alberto Zanetti, et al. To cite this version: Andrea Marzoli, Hervé Bertrand, Nasrrddine Youbi, Sara Callegaro, Renaud Merle, et al.. The Central Atlantic Magmatic Province (CAMP) in Morocco. Journal of Petrology, Oxford University Press (OUP), 2019, 60 (5), pp.945-996. 10.1093/petrology/egz021. hal-02405965 HAL Id: hal-02405965 https://hal.univ-lorraine.fr/hal-02405965 Submitted on 12 Dec 2019 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. J OURNAL OF Journal of Petrology, 2019, Vol. 60, No. 5, 945–996 doi: 10.1093/petrology/egz021 P ETROLOGY Advance Access Publication Date: 19 April 2019 Original Article The Central Atlantic Magmatic Province (CAMP) in Morocco Andrea Marzoli 1*, Herve´ Bertrand2, Nasrrddine Youbi3,4, Downloaded from https://academic.oup.com/petrology/article-abstract/60/5/945/5475177 by guest on 13 December 2019 Sara Callegaro 5, Renaud Merle6, Laurie Reisberg7, Massimo Chiaradia8, Sarah I. Brownlee9, Fred Jourdan10, Alberto Zanetti11, Joshua H.F.L. Davies8†, Tiberio Cuppone1, Abdelkader Mahmoudi12, Fida Medina13, Paul R.
    [Show full text]
  • Crustal Thickness Control on Sr/Y Signatures of Recent Arc Magmas
    OPEN Crustal thickness control on Sr/Y SUBJECT AREAS: signatures of recent arc magmas: an PETROLOGY GEOCHEMISTRY Earth scale perspective Massimo Chiaradia Received 4 November 2014 Section of Earth and Environmental Sciences, University of Geneva, Rue des Maraıˆchers 13, 1205 Geneva, Switzerland. Accepted 7 January 2015 Arc magmas originate in subduction zones as partial melts of the mantle, induced by aqueous fluids/melts Published liberated by the subducted slab. Subsequently, they rise through and evolve within the overriding plate crust. 29 January 2015 Aside from broadly similar features that distinguish them from magmas of other geodynamic settings (e.g., mid-ocean ridges, intraplate), arc magmas display variably high Sr/Y values. Elucidating the debated origin of high Sr/Y signatures in arc magmas, whether due to mantle-source, slab melting or intracrustal processes, is instrumental for models of crustal growth and ore genesis. Here, using a statistical treatment of .23000 Correspondence and whole rock geochemical data, I show that average Sr/Y values and degree of maturation (MgO depletion at requests for materials peak Sr/Y values) of 19 out of 22 Pliocene-Quaternary arcs correlate positively with arc thickness. This should be addressed to suggests that crustal thickness exerts a first order control on the Sr/Y variability of arc magmas through the M.C. (Massimo. stabilization or destabilization of mineral phases that fractionate Sr (plagioclase) and Y (amphibole 6 garnet). In fact, the stability of these mineral phases is function of the pressure at which magma evolves, [email protected]) which depends on crustal thickness. The data presented show also that high Sr/Y Pliocene-Quaternary intermediate-felsic arc rocks have a distinct origin from their Archean counterparts.
    [Show full text]
  • Mountain Views
    Mountain Views Th e Newsletter of the Consortium for Integrated Climate Research in Western Mountains CIRMOUNT Informing the Mountain Research Community Vol. 8, No. 2 November 2014 White Mountain Peak as seen from Sherwin Grade north of Bishop, CA. Photo: Kelly Redmond Editor: Connie Millar, USDA Forest Service, Pacifi c Southwest Research Station, Albany, California Layout and Graphic Design: Diane Delany, USDA Forest Service, Pacifi c Southwest Research Station, Albany, California Front Cover: Rock formations, Snow Valley State Park, near St George, Utah. Photo: Kelly Redmond Back Cover: Clouds on Piegan Pass, Glacier National Park, Montana. Photo: Martha Apple Read about the contributing artists on page 71. Mountain Views The Newslett er of the Consortium for Integrated Climate Research in Western Mountains CIRMOUNT Volume 8, No 2, November 2014 www.fs.fed.us/psw/cirmount/ Table of Contents Th e Mountain Views Newsletter Connie Millar 1 Articles Parque Nacional Nevado de Tres Cruces, Chile: A Signifi cant Philip Rundel and Catherine Kleier 2 Coldspot of Biodiversity in a High Andean Ecosystem Th e Mountain Invasion Research Network (MIREN), reproduced Christoph Kueff er, Curtis Daehler, Hansjörg Dietz, Keith 7 from GAIA Zeitschrift McDougall, Catherine Parks, Anibal Pauchard, Lisa Rew, and the MIREN Consortium MtnClim 2014: A Report on the Tenth Anniversary Conference; Connie Millar 10 September 14-18, 2014, Midway, Utah Post-MtnClim Workshop for Resource Managers, Midway, Utah; Holly Hadley 19 September 18, 2014 Summary of Summaries:
    [Show full text]
  • La Franja De Maricunga: Síntesis De La Evolución Del Frente Volcánico Oligoceno-Mioceno De La Zona Sur De Los Andes Centrales
    La Franja de Maricunga: síntesis de la evolución del Frente Volcánico Oligoceno-Mioceno de la zona sur de los Andes Centrales Constantino Mpodozis Servicio Nacional de Geologla y Minerla, Averida Santa Maria 0104, Paula Cornejo Casilla 10465, Santiago, Chile Suzanne M. Kay Department 01 Geological Sciences e INSTOC (Inslilute lor the Study 01 the Andrew Tittler Continents), Snee Hall, Cornell University, Ithaca, N. Y. 14853, USA RESUMEN La Franja de Maricunga, de 200 km de largo, portadora de mineralización de metales preciosos, se extiende en el borde occidental del Altiplano de Copiapó (26-28'S) y representa el frente volcánico Oligoceno-Mioceno de la zona sur de los Andes Centrales. La actividad volcánica se organiza en cinco eventos. El más antiguo (26-21 Ma) dio origen al complejo de estratovolcanes de Cerros Bravos-Barros Negros, y a los grupos de domos múltiples asociados a mineralización de Esperanza y La Coipa (26"30'-27"S) que hicieron erupción a través de una corteza de -45 km de espesor. En la zona surde la franja (27-28"S) la actividad fue más reducida y asociada a pequeños complejos de domos múltiples, con mineralización de oro y plata (Pantanillo, Refugio y La Pepa) emplazados a través de una corteza más delgada (-35-40 km). El segundo episodio (20-17 Ma) se asocia a un evento de deformación compresiva, engrosamiento cortical y disminución de la actividad volcánica. Entre los 16 -12 Ma, el volcanismo se reanudó con vigor. Los magmas asociados a los centros más antiguos del ciclo (Ojos de Maricunga, Santa Rosa, Jotabeche Norte; 16-15 Ma) evolucionaron en niveles corticales profundos, en equilibrio con granate.
    [Show full text]