A Late Cretaceous felsic magmatic suite from the Tengchong ,, The most abundant elements for each group of convex curves previously mentioned are Ce, Sm, Dy and Yb, respectively All samples of the granitoids are depleted in Ba, Sr, P and Ti, and the degree of depletion increases from the GPM to the XMS and XFS, as seen in the primitive mantle-normalized trace-element spider diagramEvolution of Alkalic Magma Systems: Insight from Coeval ,, The magmatic differentiation of alkalic volcanic suites can be subdivided into fractionation lineages (Coombs & Wilkinson, 1969) The silica-saturated to mildly-undersaturated lineage ranges from alkali basalt and hawaiite to mugearite, benmoreite and trachyte, and occasionally to alkalic rhyoliteRecycled ancient ghost carbonate in the Pitcairn mantle ,, Aug 28, 2018· Lavas from Pitcairn Island are the best candidates for exploring the origin of the enigmatic EM1 component found in some mantle plumes because they show the most extreme isotopic compositions of Sr, Nd, Hf, and Pb that define the EM1 component We find that these lavas have the lowest δ26Mg values so far recorded in oceanic basalts Subducted late Archean dolomite-bearing ,ASSIMILATION OF SOLIDS DURING ASCENT OF MAGMAS ,, The deep source region of the Bartoy magmas (22-25 kb [lo]), coupled with the overlying thick, Archean crust, facilitate detection of crustal assimilation within the ascended, mantle-derived magmas Unlike lunar lavas, the Bartoy suite contains abundant mafic xenoliths, cm-sized megacrysts, and fine- to coarse-grained xenocrystsMinerals | Free Full, A1-type granite xenoliths occur in alkali basalts erupted during Pliocene–Pleistocene continental rifting of Carpathian back-arc basin (Central Europe) The Pliocene (52 Ma) peraluminous calc-alkalic granite contains unusually high concentrations of critical metals bound in Nb, Ta, REE, U, Th-oxides typical for silica-undersaturated alkalic granites, and syenites: columbite-Mn ,.
30 MINERAL COMPOSITIONS IN LEG 144 LAVAS AND ,, and may provide some insight into the tholeiitic or alkalic nature However, there is considerable overlap in the clinopyroxene compo-sitions from Hawaiian tholeiitic and alkalic lavas (Fig 1 A) By itself, this diagram is not diagnostic of the silica-saturation of a magma The second diagram is a plot of Al(z) vs TiO2 after Le Bas (1962 ,A Bimodal Alkalic association on Tu Le basin: Their ,, On the other hand, the felsic magmas of Jurassic and Cretaceous ages show different geochemical features, with SiO 2 = 62 - 78 % wt, (Na 2 O+K 2 O) = 53 - 102 % wt, significant Eu anomalies (Eu/Eu* = 01 - 054), and enrichment in HFSE (Nb, Ta, Zr) and LILE (Rb, Th, U, K) along with pronounced depletions in Ba, Sr, P and Ti in the primitive ,Magma dynamics of ancient Mt Etna inferred from ,, Sep 28, 2017· Figure 1 (a) Ce contents of TSC cpx as a function of single-cpx pressure estimates (1σ uncertainty) superimposed on Etna stratigraphy (after Spilliaert et al, 2006)(b) Proportions of ancient Etna barometry from this study and previous work (cfSupplementary Information, n = 287) (c) TSC cpx and 2001 eruption cpx (Viccaro et al, 2006) shown with Hyblean pyroxenite and peridotite cpx fields ,Chapter 19: Continental Alkaline Magmatism, The last events in many complexes are late pods of Fe and REE-rich carbonatit A fenite aureole surrounds the carbonatite phases and perhaps also the alkaline silicate magmas After Le Bas (1987) Carbonatite magmas Mineral Mag, 44, 133-40 Winter (2001) An Introduction to Igneous and Metamorphic Petrology Prentice HallShield, Mar 01, 2006· Alkalic magmas may also be generated routinely during fluctuations in melt production for Hawaiian shield volcanoes and be injected into the primary conduit This idea can be tested by examining the compositions of melt inclusions in early-formed olivine crystals from tholeiitic lavas erupted from the summit reservoir.
Source materials for inception stage Hawaiian magmas: Pb ,, 1 Introduction  Hawaiian volcanoes are fed by a mantle plume that impinges the base of the drifting Pacific plate As the volcanoes grow, their magma compositions change, beginning with alkalic to tholeiitic basalts in the preshield stage, through voluminous tholeiitic basalts in the shield stage, and ending with alkali basaltic and other highly alkalic suites in the postshield and ,Metal, The Mt Milligan deposit is a tilted (~45°) Cu-Au alkalic porphyry located 155 km northwest of Prince George, BC, Canada It is the youngest of the BC alkalic porphyry deposits, all of which formed between 210 to 180 Ma in an extensive belt of K-enriched rocks related to the accretion of the Quesnellia-Stikinia superterrane to ancestral North America Mt Milligan has a measured and ,Understanding Degassing and Transport of CO2, Aug 04, 2017· Alkalic magmas provide a critical test for CO 2-fluxing because they typically have high magmatic CO 2 concentrations, inherited from their generation by low degrees of partial melting and possible enriched mantle sources (Sun & McDonough, 1989; Dasgupta et al, 2007)Editorial Manager(tm) for Mineralium Deposita Manuscript Draft, Gold enrichment in oceanic alkalic magmas has also been demonstrated from Hawaii, where Sisson (2003) documented gold concentrations up to 36 ppb in fresh, early- , Gd Dy Tb Ho Tm Lu Y Er Yb Cs Ba Rb U Th Ta Nb K La Ce Pb Sr Pr P Sm Nd Zr Eu Hf Ti Gd Dy Tb Ho Tm Lu Y Er Yb 01 1 10 100 1000 Primitive Mantle Avg NMORBPyroclastic Rocks | Professor Richard V Fisher, Professor ,, Pyroclastic Rocks is the first modern comprehensive treatment of what they are and how they were formed The subject is discussed against a background of plate tectonics theory and modern advances in volcanology, sedimentology and igneous petrology.
Geochemistry of Tertiary Igneous Rocks of Northern Luzon ,, Geochemistry of Tertiary Igneous Rocks of Northern Luzon, Philippines: Evidence for a Back-Arc Setting for Alkalic Porphyry Copper-Gold Deposits and a Case for Slab Roll-Back? Hollings, P, Wolfe, R, Cooke, D R, Waters, P JCalc, The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic seri A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ,Understanding Degassing and Transport of CO2, Alkalic magmas provide a critical test for CO 2-fluxing because they typically have high magmatic CO 2 concentrations, inherited from their generation by low degrees of partial melting and possible enriched mantle sources (Sun & McDonough, 1989; Dasgupta et al, 2007)Chronology, chemistry, and origin of trachytes from ,, These alkalic magmas carry xenoliths of cumulates from both tholeiitic and alkalic lavas, and rarely include fragments of syenite from the frozen upper reservoir (eg, vent v4bo11 near the summit) Later explosive volcanic events, such as at Waha Pele, also carried fragments of trachyte flows to the surface(PDF) High, This analysis reveals that for melts with intermediate compositions, the affinity of TiO2 for amphibole rises in alkalic magmas Accordingly, mildly alkalic trachytoid to subalkaline medium- to ,.
Lithium enrichment in intracontinental rhyolite magmas ,, Aug 16, 2017· Magmas of MVF, which formed in crust transitional between the felsic Precambrian craton and accreted island arc terranes 22, have more than twice the amount of Li (Li vc ~1400 ppm) than similar weakly peralkaline (~700 ppm Zr) magmas at High Rock and Primavera that formed on crust comprised of mafic accreted arc terranes (Li vc ~600 ppm) (Fig 4a)Contrasting Tectonic Settings and Sulfur Contents of ,, We refer to these as IOCG deposits and note that they share many similarities with magnetite-rich, alkalic-type porphyry Cu-Au deposits formed in back-arc settings (Harris et al, 2013), suggesting a continuum of broadly subduction related magmatic-hydrothermal deposit types, differentiated largely by their sulfur contents and the sulfur ,(PDF) The petrology and geochemistry of volcanic rocks on ,, A possible mechanism for producing sub-alkalic magmas from alkalic parental magmas is contamination by silica-oversaturated, incompatible-element-enriched crustal rocks As mentioned above, isotopic compositions, especially 207 Pb/ 206 Pb, of two of the Sub-ALK series rocks could be explained by this mechanism (Fig 11)Rare Earth Elements in some representative arc lavas, 10Be created by cosmic rays + oxygen and nitrogen in upper atmosphere and is eventually incorporated in clay-rich oceanic sediments 10Be has a half-life of only 15 Ma so after ~6 half lives (10 Ma), 10Be is no longer detectable10Be/9Be averages about 5000 x 10-11 in the uppermost oceanic sediments but in mantle-derived MORB and OIB magmas, & continental(PDF) Degassing of alkalic basalts, The higher solubility of CO 2 in alkalic magmas causes vapor saturation in CO 2 -bearing alkalic magmas to be reached at lower pressures than in CO 2 -bearing tholeiitic magmas having identical ,.
Hornblende fractionation in high, Hbl fractionation and high An content of plagioclase ( 90) in both rock series imply that both magmas are rich in H2O H2O contents are estimated to be up to 4 wt% for both TH and CA magmas (Hamada and Fujii, 2007) Our model is incompatible with a common model, in ,Amphibole megacrysts as a probe into the deep plumbing ,, Mar 16, 2017· Amphibole has been discussed to potentially represent an important phase during early chemical evolution of arc magmas, but is not commonly observed in eruptive arc rocks Here, we present an in-depth study of metastable calcic amphibole megacrysts in basaltic andesites of Merapi volcano, Indonesia Radiogenic Sr and Nd isotope compositions of the amphibole megacrysts overlap with the ,
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