The Mt. Edgecumbe Volcanic Field, Alaska: An Example of Tholeiitic and Calc-Alkaline Volcanism

1981 ◽  
Vol 89 (4) ◽  
pp. 459-477 ◽  
Author(s):  
Daniel G. Kosco
Keyword(s):  
Volcanic Field ◽  
Calc Alkaline ◽  
Alkaline Volcanism

Post-collisional high-K calc-alkaline volcanism in Tengchong volcanic field, SE Tibet: constraints on Indian eastward subduction and slab detachment

2015 ◽  
Vol 172 (5) ◽  
pp. 624-640 ◽  
Author(s):  
Zhengfu Guo ◽  
Zhihui Cheng ◽  
Maoliang Zhang ◽  
Lihong Zhang ◽  
Xiaohui Li ◽  
...  
Keyword(s):  
Volcanic Field ◽  
Calc Alkaline ◽  
Alkaline Volcanism ◽  
High K ◽  
Se Tibet

Volcanism in an arc-transform transition zone: the stratigraphy of the St. Clare Creek volcanic field, Wrangell volcanic belt, Yukon, Canada

1992 ◽  
Vol 29 (3) ◽  
pp. 446-461 ◽  
Author(s):  
Thomas Skulski ◽  
Don Francis ◽  
John Ludden
Keyword(s):  
Volcanic Belt ◽  
Volcanic Field ◽  
Calc Alkaline ◽  
Geochronological Data ◽  
Volcanic Stratigraphy ◽  
Central Type ◽  
Tectonic Transition ◽  
Composite Volcano ◽  
Alkaline Volcanism ◽  
Regional Tectonic

The St. Clare Creek volcanic field in the southwestern Yukon overlies a tectonic transition in the Wrangell volcanic belt between subduction to the northwest in Alaska and transform faulting along the Duke River fault in the southeast. Two large polygenetic volcanic centres dominated the Miocene landscape of the St. Clare Creek field: the 18–16 Ma Wolverine centre and the 16–10 Ma Klutlan centre. The Wolverine centre evolved from a small alkaline shield volcano at 18 Ma, from which alkaline basalts, hawaiites and mugearites erupted, to a larger composite volcano between 18 and 16 Ma composed of transitional basalt, basaltic trachyandesite, trachyte and rhyolite lavas, and pyroclastic rocks. The youngest Wolverine lavas are calc-alkaline basaltic andesites, andesites, and hybrid lavas (transitional–calc-alkaline). This temporal progression from alkaline through transitional to calc-alkaline volcanism is accompanied by a systematic increase in the degree of silica saturation and decrease in Fe/Si, Nb/Y, and P/Y ratios. Klutlan lavas have lower Nb/Y and P/Y ratios and are characterized by an opposite eruption sequence. The earliest Klutlan lavas (16–13 Ma) erupted from a composite volcano and include calc-alkaline andesite, rhyolite, and hybrid trachyandesite lavas, followed by transitional basaltic trachyandesites, trachyandesites, trachytes, and rhyolites. Klutlan vulcanism between 13 and 11 Ma was dominated by basaltic fissure eruptions on the southern flanks of the earlier centre and include early mildly alkaline basalts followed by more voluminous transitional basalts. Volcanism reverted to a more central type of activity between 11 and 10 Ma and includes calc-alkaline dacite lava followed by transitional basaltic trachyandesite, trachyandesite, and trachyte lavas.The volcanic stratigraphy of the St. Clare Creek field and 40Ar/39Ar geochronological data provide the basis for understanding the origin of St. Clare magmas in a regional tectonic context. Early Wolverine alkaline volcanism largely reflects leaky transform faulting, whereas subsequent transitional and calc-alkaline lavas record the onset of subduction-related volcanism at the margins of the then active Wrangell arc. The opposite eruption sequence at the Klutlan centre records the demise of subduction-related volcanism between 16 and 13 Ma, due to northwestward migration of the subducted plate. Upwelling of asthenospheric mantle in place of the subducted slab led to the generation of transitional basalts between 13 and 11 Ma, which resulted in more evolved lavas between 11 and 10 Ma.

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.

scholarly journals Magmatic sulfides in high-potassium calc-alkaline to shoshonitic and alkaline rocks

Solid Earth ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Ariadni A. Georgatou ◽  
Massimo Chiaradia
Keyword(s):  
Solid Solution ◽  
Early Stage ◽  
Volcanic Field ◽  
Geodynamic Setting ◽  
Calc Alkaline ◽  
High Potassium ◽  
Western Turkey ◽  
Monosulfide Solid Solution ◽  
Magmatic Sulfides ◽  
Saturation Stage

Abstract. We investigate the occurrence and chemistry of magmatic sulfides and their chalcophile metal cargo behaviour during the evolution of compositionally different magmas from diverse geodynamic settings both in mineralised and barren systems. The investigated areas are the following: (a) the Miocene Konya magmatic province (hosting the Doğanbey Cu–Mo porphyry and Inlice Au epithermal deposits, representing post-subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe, and Beydagi volcanoes, the latter associated with the Kişladağ Au porphyry in western Turkey, representing post-subduction). For comparison we also investigate (c) the barren intraplate Plio-Quaternary Kula volcanic field west of Usak. Finally, we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu–Mo and Cascabel Cu–Au porphyry deposits, representing subduction). The volcanism of the newly studied areas ranges from basalts to andesites–dacites and from high-K calc-alkaline to shoshonitic series. Multiphase magmatic sulfides occur in different amounts in rocks of all investigated areas, and, based on textural and compositional differences, they can be classified into different types according to their crystallisation at different stages of magma evolution (early versus late saturation). Our results suggest that independently of the magma composition, geodynamic setting, and association with an ore deposit, sulfide saturation occurred in all investigated magmatic systems. Those systems present similar initial metal contents of the magmas. However, not all studied areas present all sulfide types, and the sulfide composition depends on the nature of the host mineral. A decrease in the sulfide Ni∕Cu (a proxy for the monosulfide solid solution (mss) to intermediate solid solution (iss) ratio) is noted with magmatic evolution. At an early stage, Ni-richer, Cu-poorer sulfides are hosted by early crystallising minerals, e.g. olivine–pyroxene, whereas, at a later stage, Cu-rich sulfides are hosted by magnetite. The most common sulfide type in the early saturation stage is composed of a Cu-poor, Ni-rich (pyrrhotite mss) phase and one to two Cu-rich (cubanite, chalcopyrite iss) phases, making up ∼84 and ∼16 area % of the sulfide, respectively. Sulfides resulting from the late stage, consisting of Cu-rich phases (chalcopyrite, bornite, digenite iss), are hosted exclusively by magnetite and are found only in evolved rocks (andesites and dacites) of magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

scholarly journals Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

2019 ◽  
Author(s):  
Ariadni Georgatou ◽  
Massimo Chiaradia
Keyword(s):  
Solid Solution ◽  
Early Stage ◽  
Volcanic Field ◽  
Geodynamic Setting ◽  
Calc Alkaline ◽  
Western Turkey ◽  
Epithermal Deposits ◽  
High K ◽  
Wide Range ◽  
Magmatic Sulphides

Abstract. We investigate in both mineralised and barren systems the occurrence and chemistry of magmatic sulphides and their chalcophile metal cargo behaviour during evolution of compositionally different magmas in diverse geodynamic settings. The investigated areas are: (a) the Miocene Konya magmatic province (hosting the Doganbey Cu-Mo and Inlice Au-epithermal deposits) (Post-Subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe and Beydagi volcanoes, the latter associated with the Kisladag Au porphyry) in Western Turkey (Post-Subduction). For comparison we also investigate (c) the barren Plio-Quaternary Kula volcanic field, west of Usak (Intraplate) and finally we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu-Mo and Cascabel Cu-Au porphyry deposits) (Subduction). The volcanism of the studied areas displays a wide range of SiO2 spanning from basalts to andesites/dacites and from high K-calc-alkaline to shoshonitic series. Multiphase magmatic sulphides occur in different amounts in all investigated areas and based on textural and compositional differences, they can be classified in different types, which crystallised at different times (early versus late saturation). A decrease in the sulphide Ni/Cu (proxy for mss-monosulphide solid solution/iss-intermediate solid solution) ratio is noted with magmatic evolution. Starting with an early stage, saturating Ni-richer/Cu-poorer sulphides hosted by early crystallising minerals e.g. olivine/pyroxene, leading up to a later stage, producing Cu-richer sulphides hosted by magnetite. The most common sulphide type resulting from an early saturating stage is composed of a Cu-poor/Ni-rich (pyrrhotite/mss) and one/two Cu-rich (cubanite, chalcopyrite/iss) phases making up 84 and 16 area % of the sulphide, respectively. Our results suggest that independently of the magma composition, geodynamic setting and whether or not the system has generated an ore deposit on the surface, sulphide saturation occurred in variable degrees in all studied areas and magmatic systems and is characterised by a similar initial metal content of the magmas. However not all studied areas present all sulphide types and the sulphide composition is dependent on the nature of the host mineral. In particular sulphides, resulting from the late stage, consisting of Cu-rich phases (chalcopyrite ,bornite, digenite/iss) are hosted exclusively by magnetite and are found only in magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30′–37°S), Argentina

2015 ◽  
Vol 64 ◽  
pp. 365-380 ◽  
Author(s):  
Vanesa D. Litvak ◽  
Mauro G. Spagnuolo ◽  
Andrés Folguera ◽  
Stella Poma ◽  
Rosemary E. Jones ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Late Cenozoic ◽  
Calc Alkaline ◽  
South Central ◽  
Alkaline Volcanism ◽  
Shallow Subduction ◽  
Back Arc
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