Two calc-alkaline volcanic trends in the Archean: Trace element evidence

1979 ◽  
Vol 70 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Thomas E. Ewing
Keyword(s):  
Trace Element ◽  
Calc Alkaline

Petrographic, Geochemical and Isotopic (Sr–Nd–Pb–Os) Study of Plio-Quaternary Volcanics and the Tertiary Basement in the Jorullo-Tacámbaro Area, Michoacán-Guanajuato Volcanic Field, Mexico

2019 ◽  
Vol 60 (12) ◽  
pp. 2317-2338 ◽  
Author(s):  
Marie-Noëlle Guilbaud ◽  
Claus Siebe ◽  
Christine Rasoazanamparany ◽  
Elisabeth Widom ◽  
Sergio Salinas ◽  
...  
Keyword(s):  
Trace Element ◽  
Crustal Contamination ◽  
Volcanic Belt ◽  
Volcanic Field ◽  
Calc Alkaline ◽  
Trace Element Pattern ◽  
Alkaline Rocks ◽  
Rock Types ◽  
Oceanic Sediments ◽  
Element Pattern

Abstract The origin of the large diversity of rock types erupted along the subduction-related Trans-Mexican Volcanic Belt (TMVB) remains highly debated. In particular, several hypotheses have been proposed to explain the contemporary eruption of calc-alkaline and alkaline magmas along the belt. The Michoacán-Guanajuato Volcanic Field (MGVF) is an atypical, vast region of monogenetic activity located in the western-central part of the TMVB. Here we present new petrographic, geochemical, and isotopic (Sr–Nd–Pb–Os) data on recent volcanics in the Jorullo-Tacámbaro area that is the closest to the oceanic trench. TMVB-related volcanics in this area are Plio-Quaternary (<5 Ma) and mainly form a calc-alkaline series from basalts to dacites, with rare (<5 vol. %) alkaline rocks that range from trachybasalts to trachydacites, and transitional samples. Crystal textures are consistent with rapid crystallization at shallow depth and processes of mixing of similar magma batches (magma recharge). All of the samples exhibit an arc-type trace element pattern. Alkaline and transitional magmas have higher Na2O and K2O, lower Al2O3, and higher concentrations in incompatible elements (e.g. Sr, K, Ba, Th, Ce, P) compared to calc-alkaline rocks. Calc-alkaline rocks are similar isotopically to transitional and alkaline samples, except for a few low 87Sr/86Sr samples. Sr, Nd and Pb isotopes do not correlate with MgO or 187Os/188Os, indicating that they were not significantly influenced by crustal contamination. Isotopic and trace-element systematics suggest that the Tacámbaro magmas are produced by melting of a mantle wedge fluxed by fluids derived from a mixture of subducted sediments and altered oceanic crust. Alkaline and transitional magmas can be derived from a lower degree of partial melting of a similar source to that of the calc-alkaline rocks, whereas the few low 87Sr/86Sr calc-alkaline rocks require a lower proportion of fluid derived from oceanic sediments and crust. Volcanism at the trenchward edge of the MGVF was thus driven purely by subduction during the last 5 Ma, hence discarding slab rollback in this sector of the TMVB.

Nature des sources des composants andesitiques des Gres du Champsaur et des Gres de Taveyannaz; implications dans l'evolution des Alpes occidentales au Paleogene

2001 ◽  
Vol 172 (4) ◽  
pp. 487-501 ◽  
Author(s):  
Maud Boyet ◽  
Henriette Lapierre ◽  
Marc Tardy ◽  
Delphine Bosch ◽  
Rene Maury
Keyword(s):  
Trace Element ◽  
Western Alps ◽  
Northern Italy ◽  
Calc Alkaline ◽  
Magmatic Source ◽  
Isotopic Compositions ◽  
Alpine Zone ◽  
Internal Zone ◽  
Isotopic Geochemistry

Abstract Paleogene magmatism is widespread in the western Alps and its origin is still a matter of debate. It consists of calc-alkaline and shoshonitic suites with mainly granodioritic intrusions in the Internal Zone (northern Italy), andesitic volcanism in the Delphino-Helvetic Zone (French-Swiss domain) and the Esterellite intrusions in Provence. In the External Alpine Zone, the Taveyannaz Sandstones and the Champsaur Sandstones preserve andesitic pebbles and mineral fragments dated at 32 Ma. On the basis of trace-element and isotopic geochemistry (Sr, Nd, Pb and O) of mineral separates (amphibole, pyroxene and plagioclase) and andesitic clasts, we characterise the nature of magmatic source(s) and compare the isotopic compositions of the andesites with those of well known Paleogene igneous suites.

Pluton source varition over two magmatic pulses in the white-inyo range, central-eastern California : implications for paleozoic and mesozoic tectonic reconstructions

2018 ◽  
Author(s):  
◽  
Elizabeth M Kenderes
Keyword(s):  
Trace Element ◽  
North American ◽  
Oceanic Island ◽  
Island Arc ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Regional Study ◽  
University Of Missouri ◽  
Tectonic Model ◽  
Central Eastern

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This dissertation uses compositions of plutons in the White-Inyo Range (WIR) of central-eastern California, which is an important tectonic boundary as it is the easternmost extent of the Mesozoic Cordilleran arc and the western edge of Basin and Range extension. The main goal of this dissertation is to understand the lithospheric structure of this area in relation to the broader regional tectonics. Chapters 2 and 3 specifically investigate the Eureka Valley-Joshua Flat-Beer Creek (EJB) composite arc pluton, from its source to emplacement. The EJB pluton is one of a small number of monzonitic plutons cotemporally emplaced with the primarily calc-alkaline North American Mesozoic Cordilleran arc. Mineral major and trace element compositions are used to show the crystallization sequence and pressures and temperatures of mineral crystallization. These data are used to make interpretations about the EJB pluton's formation from source to emplacement. Additionally, whole rock major and trace element compositions and isotopic data show that the EJB pluton has a unique source from the calc-alkaline plutons: an underplated, eclogitized oceanic island arc. Chapter 4 is a regional study of the WIR, and it includes whole rock major and trace element and isotopic data to interpret the three distinct sources of plutons: (1) the eclogitized oceanic island arc, (2) enriched lithospheric mantle, and (3) Proterozoic North American basement. Recognizing the timing of the generation of these plutons in relation to their sources is crutial to understanding the tectonic history of the WIR area. This dissertation presents tectonic model for western North America from the Early Proterozoic to Late Cretaceous

scholarly journals The Alkaline Lamprophyres of the Dolomitic Area (Southern Alps, Italy): Markers of the Late Triassic Change from Orogenic-like to Anorogenic Magmatism

2019 ◽  
Vol 60 (6) ◽  
pp. 1263-1298 ◽  
Author(s):  
Federico Casetta ◽  
Ryan B Ickert ◽  
Darren F Mark ◽  
Costanza Bonadiman ◽  
Pier Paolo Giacomoni ◽  
...  
Keyword(s):  
Trace Element ◽  
Southern Alps ◽  
Late Triassic ◽  
Small Scale ◽  
Main Process ◽  
Calc Alkaline ◽  
Isotopic Signatures ◽  
Systematic Uncertainties ◽  
High K ◽  
Magmatic Event

AbstractWe present the first complete petrological, geochemical and geochronological characterization of the oldest lamprophyric rocks in Italy, which crop out around Predazzo (Dolomitic Area), with the aim of deciphering their relationship with Triassic magmatic events across the whole of the Southern Alps. Their Mg# of between 37 and 70, together with their trace element contents, suggests that fractional crystallization was the main process responsible for their differentiation, together with small-scale mixing, as evidenced by some complex amphibole textures. Moreover, the occurrence of primary carbonate ocelli suggests an intimate association between the alkaline lamprophyric magmas and a carbonatitic melt. 40Ar/39Ar data show that the lamprophyres were emplaced at 219·22 ± 0·73 Ma (2σ; full systematic uncertainties), around 20 Myr after the high-K calc-alkaline to shoshonitic, short-lived, Ladinian (237–238 Ma) magmatic event of the Dolomitic Area. Their trace element and Sr–Nd isotopic signatures (87Sr/86Sri = 0·7033–0·7040; 143Nd/144Ndi = 0·51260–0·51265) are probably related to a garnet–amphibole-bearing lithosphere interacting with an asthenospheric component, significantly more depleted than the mantle source of the high-K calc-alkaline to shoshonitic magmas. These features suggest that the Predazzo lamprophyres belong to the same alkaline–carbonatitic magmatic event that intruded the mantle beneath the Southern Alps (e.g. Finero peridotite) between 190 and 225 Ma. In this scenario, the Predazzo lamprophyres cannot be considered as a late-stage pulse of the orogenic-like Ladinian magmatism of the Dolomitic Area, but most probably represent a petrological bridge to the opening of the Alpine Tethys.

Pontiac metavolcanic rocks within the Cadillac tectonic zone, McWatters, Abitibi Belt, Quebec

1993 ◽  
Vol 30 (7) ◽  
pp. 1521-1531 ◽  
Author(s):  
David Morin ◽  
Michel Jébrak ◽  
Marc Bardoux ◽  
Normand Goulet
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Rare Earth Element ◽  
Greenstone Belt ◽  
Earth Element ◽  
Calc Alkaline ◽  
Tectonic Zone ◽  
Southern Boundary ◽  
Abitibi Greenstone Belt ◽  
Metavolcanic Rocks

The McWatters metavolcanic rocks are structurally bounded lenses within the Cadillac tectonic zone on the southern boundary of the Abitibi greenstone belt. They comprise komatiite, tholeiitic basalt and gabbro, and calc-alkaline andesitic lavas and volcaniclastic rocks cut by calc-alkaline dioritic and lamprophyric dykes. The McWatters basalts are mid-ocean-ridge basalt type tholeiites exhibiting low incompatible trace element contents and [La/Yb]N < 1. They may have formed via relatively high degree partial melting of a rare-earth element depleted mantle source. The andesites exhibit chondrite-normalized trace-element patterns with light-rare-earth and large-ion lithophile element enrichments and negative Nb and Ti anomalies, comparable to those of subduction-related calc-alkaline andesites. McWatters units are distinct from nearby Blake River Group rocks, despite comparable lithological assemblages and some common geochemical characteristics. The McWatters basalts exhibit lower Ti/Y, Zr/Y, and La/Yb than the Blake River tholeiites, whereas the McWatters andesites display lower Ti/Zr and higher Zr/Y than the Blake River calc-alkaline units. The McWatters tholeiites can be correlated with northern Pontiac Group tholeiitic units based on similar trace-element ratios and parallel rare-earth-element patterns. Thus, the McWatters tholeiites represent Pontiac rocks, underthrust beneath the southern Abitibi belt and appearing as isolated and retrograded lenses in the Cadillac tectonic zone. They may represent the remnants of an ocean basin that once separated the southern Abitibi greenstone belt from the Pontiac Subprovince.

Deciphering magmatic processes in calc-alkaline plutons using trace element zoning in hornblende

2016 ◽  
Vol 101 (2) ◽  
pp. 328-342 ◽  
Author(s):  
Calvin G. Barnes ◽  
Valbone Memeti ◽  
Nolwenn Coint
Keyword(s):  
Trace Element ◽  
Calc Alkaline ◽  
Magmatic Processes

Ordovician volcanism in the Welsh Borderland

1986 ◽  
Vol 123 (6) ◽  
pp. 629-640 ◽  
Author(s):  
P. T. Leat ◽  
R. S. Thorpe
Keyword(s):  
Trace Element ◽  
Basaltic Andesite ◽  
Calc Alkaline ◽  
Basalt Flow ◽  
Chemical Alteration ◽  
Marginal Basin ◽  
Southeastern Margin ◽  
Trace Element Contents ◽  
Element Contents ◽  
Rhyolitic Volcanism

AbstractBasaltic, andesitic and rhyodacitic/rhyolitic volcanism was widespread during Ordovician time in the Welsh Basin. New chemical data are presented for Llanvirn to Caradoc lavas and tuffs from the Welsh Borderland which, during Ordovician time, formed the southeastern margin of the Welsh Basin. In view of the observed chemical alteration, immobile elements are used in the interpretation of the original geochemical character. The data indicate that the Llanvirn Stapeley volcanic group of the Shelve inlier was a bimodal basalt/basaltic andesite – rhyodacite/rhyolite association. The basalts have trace element contents of tholeiitic associations with a subduction-related character. The Caradoc Whittery and Hagley volcanic groups of the Shelve inlier comprise lavas and tuffs of calc-alkaline andesite. Blocks sampled from the Breidden Hills show that these were also derived from a calc-alkaline volcano. Associated Caradoc pumice- and ash-flow deposits from the Breidden Hills are probably of altered calc-alkaline rhyodacite/rhyolite composition. The Sibdon Carwood basalt flow, the only known example of Ordovician volcanism east of the Pontesford–Linley and Church Stretton lineaments, has transitional tholeiitic to alkaline character, with trace element contents influenced by subduction-related processes. The overall tholeiitic to calc-alkaline nature of the magmatism is consistent with the view that, during Llanvirn to Caradoc time, the Welsh Basin was an ensialic marginal basin.

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