Multivariate statistical analysis involving hierarchical clusters was carried out for basaltic samples (and associated units) from Khandwa (21°49'N, 76°21'E). ‘Highly significant’ or ‘significant’ linear correlation coefficient values (r) corresponding to different minerals (namely, olivine, clinopyroxene and plagioclase), denote several oxides (as for example, MgO, FeO, SiO$_2$, Al$_2$O$_3$, Na$_2$O, CaO and TiO$_2$) which were used for construction of dendrograms. Critical analysis of hierarchical patterns revealed that at the outset of magmatic crystallization, heterogeneous (${\sim}$greater symmetry) clusters are present. For the crystallization of the lava flows, the ‘bulk level of crystallization’ (in respect of clinopyroxene and plagioclase) varies from ${\sim}$30 to ${\sim}$60%, whereas their ‘ultimate crystallization’ appears to be quite high (${\sim}$80 to ${\sim}$97%). The bulk crystallization of the lava flows shows a broad control of ambient temperature. The dyke system (feeder dyke and chilled dyke) also shows bulk crystallization pattern similar to that of lava flows. Cluster analyses for basement gabbroic rock suggest that there is a wide compositional spectrum for the accumulate portion, whereas the intercumulus portion is marked by relatively restricted compositions. In general, the present CA (cluster analysis) clearly indicates progressive amalgamation of clusters (and their concomitant fall of symmetry) with advancing differentiation.

$\bf{Highlights}$

$\bullet$ Multivariate statistical analysis from a portion of eastern Deccan volcanic province deciphers distinctive nature of crystallization.

$\bullet$ Cluster patterns indicate distinct ‘bulk level of crystallization’ and ‘ultimate crystallization’ for the lavas.

$\bullet$ Rapid quenching of dyke rocks only allows them to crystallize up to the bulk level.

$\bullet$ Ambient temperature controls bulk level of crystallization for the lavas.

Continental flood basalts of the world are represented either by picrobasalt/picrite layers (with abundant growth of olivine) or by (almost) olivine-depleted tholeiite basalts. We have taken a case study from the olivine-depleted basaltic rocks from Khandwa (21°49'N: 76°21'E) Eastern Deccan Volcanic Province. Our research shows that recent cooling experiments (available in the literature) involving a dry basalt and construction of some selected binary major element variation diagrams (entailing lever rules) can explain (and quantify) the insignificant level (${\sim}$2–4%) of olivine crystallization (${\sim}$olivine decadence) in tholeiite basalts. Such decadent olivine retains a skeletal crystallographically-oriented geometry. We contemplate that our simplistic model of olivine decadence can be extended to other flood basalt provinces of the world as well.

$\bf{Highlights}$

$\bullet$ First-time cogent model of olivine decadence in Deccan basalts

$\bullet$ Integration of newly obtained experimental data and binary variation diagrams

$\bullet$ Petrographic support validates the model

$\bullet$ Model can be extended to other continental Flood basalts