The polygenetic activity of the Develidağ volcano from Miocene to Pliocene (∼5.5 Ma) is represented by basaltic/dacitic calk-alkaline and Na-alkaline magmas on the SE rim of Central Anatolian Volcanic Province (Kayseri, Turkey). Ubiquitous resorption patterns among An-rich (> 75 XAn) plagioclase and complex pyroxene with common microlithic to porphyritic texture indicate the complex evolutionary history of magmas. Common normal zoning trend among the crystallizing phases, decreasing major element oxides, and systematic enrichment of Th, Zr, with LILE against increasing silica among rocks attests to fractional crystallization and crustal assimilation processes. Estimated intensive reservoir parameters based on mineral-only, mineral pair, and mineral-liquid equilibria demonstrate that partial crystallization of magmas spanned a broad P (kbar) / T (°C) gradient over the NNO buffer. Least-square mass balance (39–71% FC), trace element (50% AFC; r = 0.3–0.5), and pMELTS/rhyolite-MELTS (9.23–0.5 kbar, 1227–850 °C) models indicate the transition between ascent and cooling-driven fractionation, involvement of crustal material with the mixing between less evolved and evolved melts along the vertically extensive magmatic reservoir system. Micro- to mesoscale reconstruction of magmatic reservoir processes along the formation of physico-chemically distinct magma series provides a better understanding of eruptive processes and the tectonomagmatic evolution of a transcrustal reservoir system before the transtensional regime at the Central Anatolian Volcanic Province.