MnO/TiO2/P2O5: a minor element discriminant for basaltic rocks of oceanic environments and its implications for petrogenesis, Mullen, 1983

@article{Mullen198353,
title = "MnO/TiO2/P2O5: a minor element discriminant for basaltic rocks of oceanic environments and its implications for petrogenesis ",
journal = "Earth and Planetary Science Letters ",
volume = "62",
number = "1",
pages = "53 - 62",
year = "1983",
note = "",
issn = "0012-821X",
doi = "http://dx.doi.org/10.1016/0012-821X(83)90070-5",
url = "http://www.sciencedirect.com/science/article/pii/0012821X83900705",
author = "Ellen D. Mullen",
abstract = "A ternary diagram using MnO, TiO2, \{P2O5\} can discriminate between five petrotectonic environments of basaltic rocks (45–54% SiO2). Fields for mid-ocean ridge, island arc tholeiite, island arc calc-alkaline, ocean island tholeiite, and ocean island alkalic rocks were distinguished on the basis of 507 analyses from well-defined environments. Boninites plot within island arc fields. Continental tholeiites, such as the Columbia River basalts, are high in \{P2O5\} relative to MnO and TiO2, and overlap portions of all five oceanic fields. MnO is depleted relative to TiO2 in mid-ocean ridge analyses and may be controlled by early fractionation of olivine and/or clinopyroxene under conditions of lowfO2. In island arc rocks, MnO is enriched relative to TiO2 due to early crystallization of titanomagnetite in a high-fO2 environment. Primitive mid-ocean ridge and arc tholeiites have similar MnO/TiO2/P2O5 ratios which indicate a grossly similar parent magma. Increasingly differentiated basaltic rocks are more easily classified by the diagram. High relative abundances of TiO2 and \{P2O5\} in ocean island rocks are consistent with their derivation from a separate source. Despite the purported high mobility of MnO, the MnO/TiO2/P2O5 discriminant diagram may be applied to unspilitized and moderately spilitized zeolite to greenschist facies greenstones with good agreement between the environment determined by MnO/TiO2/P2O5 and by other means such as trace elements, REE, or field relations. "
}