MORE B LAXMAN
Articles written in Journal of Earth System Science
Volume 131 All articles Published: 24 August 2022 Article ID 0186 Letter
Spatial variations in the geochemical characteristics of basalts from the Deccan Volcanic Province, India: Role of mixing and assimilation fractional crystallisation
MORE B LAXMAN B NAGARAJU K NAGARAJU K VIJAYA KUMAR
In the present study, we have demarcated five zones within the Deccan Volcanic Province (DVP):
(1) Kutch, (2) Western Ghats, (3) Central Son–Narmada, (4) Eastern Son–Narmada and (5) South- Eastern Deccan
(SE DVP) to evaluate spatial geochemical variations within the DVP possibly controlled
by different eruption loci. True OIB-type unmixed trace element and isotopic signatures are demon strated
by both alkali and tholeiitic basalts from Kutch and a small proportion from Western Ghats.
However, large number of tholeiitic basaltic samples from both the zones and Central Son–Narmada zone
illustrate sub-continental lithosphere mantle (SCLM) signatures. The Eastern Son–Narmada and SE
DVP zones of the DVP show evolved compositions, but are dominantly derived from sub-lithospheric
sources. The plume–lithosphere interaction is represented by mixing and/or assimilation and fractional
crystallisation (AFC) of plume-derived melts with the sub-continental lithospheric mantle (SCLM)-
derived melts, sediments preserved in the SCLM, lower crustal (TTG-type) and upper crustal (granitic)
components. We argue that melts from the Archaean sediments preserved in the SCLM,
$\bullet$ The melts generated from the Archaean sediments preserved in the SCLM, represented by calc-alkaline lamprophyres, are most likely the components that interacted with the plume-derived as well as SCLM-derived partial melts during the formation of DVP.
$\bullet$ Mixing and/or AFC of calc-alkaline lamprophyres, TTGs and granites by plume-derived melts and SCLM peridotite-derived melts explain total geochemical spread of the Deccan basalts.
$\bullet$ Approximately, 10% mixing and/or ~20% AFC of Archean calc-alkaline lamprophyre melts can make original sub-lithosphere melts display apparent SCLM signatures.
$\bullet$ The basalts from the western side of DVP have undergone higher levels of assimilation compared to those from the eastern side.
Volume 132, 2023
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