Matches in SemOpenAlex for { <https://semopenalex.org/work/W2788396752> ?p ?o ?g. }
- W2788396752 endingPage "240" @default.
- W2788396752 startingPage "216" @default.
- W2788396752 abstract "Occurrences of high-Mg andesite (HMA) in modern volcanic arcs raise the possibility that significant volumes of continental crust could be directly derived from Earth’s mantle. Such rocks are commonly associated with subduction of young, warm oceanic lithosphere or occur in areas heated by mantle convection. A relatively rare occurrence near Mt. Shasta in the Cascades volcanic arc has been considered to represent one such primary mantle-derived magma type, from which more evolved andesitic and dacitic magmas are derived. Recognition that the Shasta area HMA is actually a hybrid mixed magma, calls into question this notion as well as the criteria upon which it is based. We report new chemical and mineralogical data for samples of the Shasta HMA that bear on the components and processes involved in its formation. Several generations of pyroxenes and olivines are present along with different generations of oxide minerals and melt inclusions. The most magnesian olivines (Fo93) exhibit disequilibria textures, exotic melt inclusions, and reaction rims of Fo87 composition; these crystals along with spongy, ~Mg# 87 orthopyroxene crystals are interpreted to be xenocrystic and do not signify a primitive mantle derivation. The groundmass is andesitic with moderate MgO content, and melt inclusions of similar compositions are hosted by equilibrium olivine (~Fo87). The bulk magma (whole rock) is more magnesian, but primarily due to incorporation of mafic minerals and ultramafic xenolith debris. We propose that the exotic crystal and lithic debris in these rocks is derived from (1) dacitic magmas of possible crustal derivation, (2) prograded ultramafic rocks in the underlying crust, and (3) random lithic debris and crystals derived from conduit wall rocks and earlier intruded magmas within the feeder plexus beneath Shasta. The HMA is inferred to represent a mixture between evolved dacitic and primitive basaltic magmas as well as incorporation of xenolithic crystal cargo. There is no compelling evidence that HMA is present in large volumes, and it is not considered to be an important parental liquid to more evolved magmas at Shasta." @default.
- W2788396752 created "2018-03-06" @default.
- W2788396752 creator A5003590659 @default.
- W2788396752 creator A5016154275 @default.
- W2788396752 date "2018-02-01" @default.
- W2788396752 modified "2023-10-16" @default.
- W2788396752 title "Petrology of “Mt. Shasta” high-magnesian andesite (HMA): A product of multi-stage crustal assembly" @default.
- W2788396752 cites W1473115938 @default.
- W2788396752 cites W1841768873 @default.
- W2788396752 cites W1965199962 @default.
- W2788396752 cites W1966013657 @default.
- W2788396752 cites W1976087859 @default.
- W2788396752 cites W1979705656 @default.
- W2788396752 cites W1987018401 @default.
- W2788396752 cites W1987501517 @default.
- W2788396752 cites W1990672888 @default.
- W2788396752 cites W1991712311 @default.
- W2788396752 cites W1992604645 @default.
- W2788396752 cites W1996072627 @default.
- W2788396752 cites W2007684610 @default.
- W2788396752 cites W2008456126 @default.
- W2788396752 cites W2008787240 @default.
- W2788396752 cites W2013857416 @default.
- W2788396752 cites W2015268400 @default.
- W2788396752 cites W2017913265 @default.
- W2788396752 cites W2018124720 @default.
- W2788396752 cites W2018598067 @default.
- W2788396752 cites W2020047493 @default.
- W2788396752 cites W2021913724 @default.
- W2788396752 cites W2022017333 @default.
- W2788396752 cites W2023130711 @default.
- W2788396752 cites W2023214376 @default.
- W2788396752 cites W2023563727 @default.
- W2788396752 cites W2023741741 @default.
- W2788396752 cites W2027069472 @default.
- W2788396752 cites W2029407151 @default.
- W2788396752 cites W2031872065 @default.
- W2788396752 cites W2035347372 @default.
- W2788396752 cites W2036304858 @default.
- W2788396752 cites W2036605653 @default.
- W2788396752 cites W2037175243 @default.
- W2788396752 cites W2038072959 @default.
- W2788396752 cites W2040126025 @default.
- W2788396752 cites W2041507297 @default.
- W2788396752 cites W2041549570 @default.
- W2788396752 cites W2041601062 @default.
- W2788396752 cites W2041912347 @default.
- W2788396752 cites W2044596835 @default.
- W2788396752 cites W2044886155 @default.
- W2788396752 cites W2045769202 @default.
- W2788396752 cites W2046755277 @default.
- W2788396752 cites W2050916063 @default.
- W2788396752 cites W2053396208 @default.
- W2788396752 cites W2053483240 @default.
- W2788396752 cites W2053721096 @default.
- W2788396752 cites W2054920148 @default.
- W2788396752 cites W2055289543 @default.
- W2788396752 cites W2055859870 @default.
- W2788396752 cites W2055909867 @default.
- W2788396752 cites W2056351208 @default.
- W2788396752 cites W2056549444 @default.
- W2788396752 cites W2057550910 @default.
- W2788396752 cites W2060401165 @default.
- W2788396752 cites W2062995566 @default.
- W2788396752 cites W2064241548 @default.
- W2788396752 cites W2071863765 @default.
- W2788396752 cites W2074579635 @default.
- W2788396752 cites W2076447745 @default.
- W2788396752 cites W2079140883 @default.
- W2788396752 cites W2080368015 @default.
- W2788396752 cites W2083104646 @default.
- W2788396752 cites W2085480633 @default.
- W2788396752 cites W2086432886 @default.
- W2788396752 cites W2087348898 @default.
- W2788396752 cites W2091342634 @default.
- W2788396752 cites W2094201191 @default.
- W2788396752 cites W2097873109 @default.
- W2788396752 cites W2099225517 @default.
- W2788396752 cites W2104736554 @default.
- W2788396752 cites W2105068734 @default.
- W2788396752 cites W2105189796 @default.
- W2788396752 cites W2108052764 @default.
- W2788396752 cites W2108819209 @default.
- W2788396752 cites W2110957968 @default.
- W2788396752 cites W2111918073 @default.
- W2788396752 cites W2117979886 @default.
- W2788396752 cites W2118152839 @default.
- W2788396752 cites W2122613640 @default.
- W2788396752 cites W2129569463 @default.
- W2788396752 cites W2129755303 @default.
- W2788396752 cites W2130218500 @default.
- W2788396752 cites W2132443428 @default.
- W2788396752 cites W2136162288 @default.
- W2788396752 cites W2136549236 @default.
- W2788396752 cites W2141929969 @default.
- W2788396752 cites W2143502114 @default.
- W2788396752 cites W2144235599 @default.
- W2788396752 cites W2146956557 @default.