The importance of parental magma composition to calc-alkaline and tholeiitic evolution: Evidence from Umnak Island in the Aleutians

1992 ◽  
Vol 97 (B1) ◽  
pp. 321 ◽  
Author(s):  
Daniel M. Miller ◽  
Charles H. Langmuir ◽  
Steven L. Goldstein ◽  
Andrew L. Franks
Keyword(s):  
Parental Magma ◽  
Calc Alkaline ◽  
Magma Composition

New FTIR data of calc-alkaline volcanic rocks from the Oas-Gutai Mts. and post eruption effects on the water content of phenocrysts

2020 ◽  
Author(s):  
Ákos Kővágó ◽  
Marinel Kovacs ◽  
Dóra Kesjár ◽  
Csaba Szabó ◽  
István Kovács
Keyword(s):  
Water Content ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Volcanic Eruptions ◽  
Ftir Spectra ◽  
Future Research ◽  
Calc Alkaline ◽  
Structural Hydroxyl ◽  
Volcanic Facies ◽  
Water Contents

<p>We studied volcanic rocks from the Oas-Gutai Mts. (Transylvania, Romania) to measure the ‘structural hydroxyl’ content of the nominally anhydrous minerals (NAMs such as clinopyroxene, plagioclase, quartz), from which water content of the parental magma can be estimated.  The Neogene volcanic chain of the Carpathian-Pannonian region (CPR), due to petrologic variability, is an excellent area for such investigation.</p><p>Recent FTIR studies on the calc-alkaline rocks from CPR, showed that the ‘structural hydroxyl’ content of NAMs could be modified during and after volcanic eruptions [1], [2], [3]. However, transmission FTIR-microscopy is an adequate technique for recognizing this these changes because FTIR spectra of the NAMs indicate signs in the case of hydroxyl loss [4].</p><p>For studying the pre-eruptive water contents clinopyroxenes are the most promising mineral because it has one of the lowest diffusion rates for hydroxyl in NAMs [5]. With the detailed study of the clinopyroxenes FTIR spectra, conclusions can be drawn concerning the potential post-eruptive loss of hydroxyl [4].</p><p>We have examined 8 volcanic rock samples, four dacite samples from Oas and one basalt two andesite and one rhyolite sample from the Gutai Mts. The samples show diverse volcanic facies such as lava, ignimbrite and debris avalanche. The diversity of samples is important for future research because it will help to choose the most adequate volcanic facies to estimate the magmatic equilibrium water contents.</p><p>The studied clinopyroxenes contain 83-371 ppm ‘structural hydroxyl’ content,which can be considered as normal values compared to the work of [6] where ‘structural hydroxyl’ content in clinopyroxenes show a range from 75 to 390 ppm in the mafic calc-alkaline lavas from Salina, Italy.</p><p>[1] Lloyd, A.S., Ferriss, E., Ruprecht, P., Hauri, E.H., Jicha, B.R., & Plank, T. (2016): Journal of Petrology, 57, pp. 1865-1886</p><p>[2] Biró, T., I. Kovács, D. Karátson, R. Stalder, E. Király, G. Falus, T. Fancsik, J. & Sándorné Kovács (2017): American Mineralogist, 102, pp.</p><p>[3] Pálos, Z., Kovács, I. J., Karátson, D., Biró, T., Sándorné Kovács, J., Bertalan, É., & Wesztergom, V. (2019): Central European Geology, 62(1)</p><p>[4] Patkó, L., Liptai, N., Kovács, I., Aradi, L., Xia, Q.K., Ingrin, J., Mihály, J., O'Reilly, S.Y., Griffin, W.L., Wesztergom, V., & Szabó, C. (2019): Chemical Geology, 507, pp. 23-41.</p><p>[5] Farver, J.R. (2010): Reviews in Mineralogy and Geochemistry, 72 (1), pp. 447–507.</p><p>[6] Nazzareni, S., Skogby H., & Zanazzi, P.F. (2011): Contributions to Mineralogy and Petrology, 162, pp. 275–288.</p>

The Chineysky gabbronorite-anorthosite layered massif (NorthernTransbaikalia, Russia): its structure, Fe-Ti-V and Cu-PGE deposits, and parental magma composition

2016 ◽  
Vol 51 (8) ◽  
pp. 1013-1034 ◽  
Author(s):  
Bronislav I. Gongalsky ◽  
Nadezhda A. Krivolutskaya ◽  
Alexey A. Ariskin ◽  
George S. Nikolaev
Keyword(s):  
Parental Magma ◽  
Magma Composition

scholarly journals Constraining the sub-arc, parental magma composition for the giant Altiplano-Puna Volcanic Complex, northern Chile

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Osvaldo González-Maurel ◽  
Frances M. Deegan ◽  
Petrus le Roux ◽  
Chris Harris ◽  
Valentin R. Troll ◽  
...  
Keyword(s):  
Parental Magma ◽  
Volcanic Complex ◽  
Northern Chile ◽  
Magma Composition

Massive sulfide deposits of the Noranda area, Quebec. II. The Aldermac mine

1991 ◽  
Vol 28 (9) ◽  
pp. 1301-1327 ◽  
Author(s):  
T. J. Barrett ◽  
S. Cattalani ◽  
F. Chartrand ◽  
P. Jones
Keyword(s):  
Volcanic Rocks ◽  
Parental Magma ◽  
Mass Gain ◽  
Massive Sulfide ◽  
Sulfide Deposit ◽  
Calc Alkaline ◽  
Sulfide Deposits ◽  
Massive Sulfide Deposits ◽  
Fractionation Trend ◽  
Felsic Volcanic

The original Aldermac mine near Noranda contained several Cu–Zn massive sulfide lenses hosted by felsic to mafic volcanic rocks of the late Archean Blake River Group. The original Nos. 3–6 orebodies, which consisted of massive pyrite, with lesser magnetite, pyrrhotite, chalcopyrite, and sphalerite, contained 1.87 Mt of Cu–Zn ore that averaged 1.47% Cu (Zn was not recovered). The orebodies occurred within felsic breccias and tuffs up to 100 m thick that are stratigraphically overlain by an extensive dome of mainly massive rhyolite and rhyodacite (up to 250 m thick and at least 550 m across). Most of the volcanic rocks that laterally flank and overlie the felsic dome are dacitic to andesitic flows, breccia, and tuff, with minor rhyolites, and associated subvolcanic sills of quartz-feldspar porphyry and gabbro.The new massive sulfide deposit, discovered in 1988, lies 150–200 m east of the mined-out orebodies, at a similar stratigraphic level within altered felsic breccia and tuff. The sulfides are mainly in the No. 8 lens, which contains 1.0 Mt at an average grade of 1.54% Cu, 4.12% Zn, 31.2 g/t Ag, and 0.48 g/t Au. Pyrite forms porphyroblastic megacrysts in a groundmass of pyrrhotite, sphalerite, magnetite, and chalcopyrite. A funnel-shaped, chloritized stockwork zone underlies the No. 8 lens and contains Cu-stringer mineralization. The No. 8 lens appears to be zoned, with overall decreasing Cu:Zn ratios from the core to the fringes of the lens. Massive sulfides in this lens have high Ag, Cd, and Hg contents relative to other massive sulfide deposits near Noranda.Ti versus Zr trends for least-altered Aldermac volcanic rocks indicate a more or less continuous magmatic fractionation trend ranging from high-Ti andesite to andesite, dacite, rhyodacite, and two distinct rhyolites (A and B). Most volcanic rocks were derived from a common parental magma that was transitional between tholeiitic and calc-alkaline compositions, as indicated by Ti–Y–Zr–Nb data and rare-earth-element distributions.Ti versus Zr trends in altered volcanic rocks indicate that silicification (mass gain) has affected some of the andesitic to rhyodacitic rocks, whereas chloritization (mass loss) has affected many of the rhyolitic rocks. Intermediate to mafic volcanic rocks above and lateral to the felsic dome are commonly silicified, possibly the result of hydrothermally remobilized silica derived from underlying felsic volcanic rocks.The orebodies appear to have formed at an eruptive hiatus between mafic → felsic and felsic → mafic cycles, during explosive activity and accumulation of felsic breccia and tuff. Ore was deposited mainly within a felsic fragmental sequence (rhyolite A), but before emplacement of the dome of rhyolite B. In compositionally diverse volcanic terrains, the contact between successive mafic–felsic and felsic–mafic cycles may be a good exploration target, in particular specific geochemical contacts within the felsic stratigraphy.

Sills associated with the Bushveld Complex, South Africa: an estimate of the parental magma composition

Lithos ◽  
1981 ◽  
Vol 14 (1) ◽  
pp. 1-16 ◽  
Author(s):  
R. Grant Cawthorn ◽  
G. Davies ◽  
A. Clubley-Armstrong ◽  
T.S. McCarthy
Keyword(s):  
South Africa ◽  
Bushveld Complex ◽  
Parental Magma ◽  
Magma Composition
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