Clues from <i>Ab Initio</i> Calculations on Titanium Isotopic Fractionation in Tholeiitic and Calc-Alkaline Magma Series
نویسندگان
چکیده
Magmatic differentiation produces positive correlations between δ49Ti and SiO2. The equilibrium Ti isotope fractionation factors of Ti-bearing minerals are essential for understanding the mechanisms driving this isotopic fractionation. We present ab initio-derived mean force constants (barium orthotitanate, potassium titanium oxide, fresnoite, diopside, geikielite, karrooite, titanite, pseudobrookite, anatase, oxide) based on density functional theory (DFT) to calculate factors. find that main driver is its coordination, with four-, five-, sixfold-coordinated characterized by 547, 462, 310 N/m, respectively. coordination number in silicate melts thought be lower than minerals, magmas toward higher values fractional crystallization. mineral-melt allow modeling observed trends tholeiitic calc-alkaline rocks. Our model results indicate first order, steeper trend versus most likely due enhanced removal into sequestered at low SiO2 concentration series compared series. δ49Ti–SiO2 trends, however, depend melt strengths bonds diverse Fe- Ti-oxides, which still uncertain. show isotopes can used reconstruct crystallization history identify magmatic parentage otherwise lack context, but further work needed drivers behind igneous
منابع مشابه
Reaction Between Ultramafic Rock and Fractionating Basaltic Magma I. Phase Relations, the Origin of Calc-alkaline Magma Series, and the Formation of Discordant Dunite
This paper presents results of modelling reaction between peridotite and fractionating tholeiitic basalt in simple and complex silicate systems. Reactions are outlined in appropriate binary and ternary silicate systems. In these simple systems, the result of reactions between 'basalt' and 'peridotite' may be treated as a combination of Fe-Mg exchange and mass transfer reactions at constant Fe/M...
متن کاملMelt/harzburgite reaction in the petrogenesis of tholeiitic magma from Kilauea volcano, Hawaii
We use the results of elevated pressure melting experiments to constrain the role of melt/mantle reaction in the formation of tholeiitic magma from Kilauea volcano, Hawaii. Trace element abundance data is commonly interpreted as evidence that Kilauea tholeiite is produced by partial melting of garnet lherzolite. We experimentally determine the liquidus relations of a tightly constrained estimat...
متن کاملAdakite magmatism within the Sabzevar ophiolite zone, NE Iran: U-Pb geochronology and Sr-Nd isotopic evidences
Numerous post-ophiolite intrusions exposed into the late Cretaceous–Paleocene Sabzevar ophiolite belt, northeast Iran. The intrusions consist of calc-alkaline intermediate to felsic rocks with metaluminous to peraluminous in nature and adakitic affinities. Based on U-Th-Pb dating on separated zircons by SHRIMP Ⅱ, the emplacement age of these rocks into the ophiolite zone is constrained to ~45 M...
متن کاملSignificance of hornblende in calc-alkaline andesites and basalts
Hornblende occurs in some andesitic and basaltic rocks of calc-alkaline affini1y, where it is commonly associated with olivine. The texture, eruption history, and composition are interpreted to indicate that hornblende commonly forms as a product of reaction between olivine and basaltic and andesitic liquids. The natural hornblendes probably formed within the crust at temperatures between 960o ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: ACS earth and space chemistry
سال: 2021
ISSN: ['2472-3452']
DOI: https://doi.org/10.1021/acsearthspacechem.1c00172