This study investigates the mineralogical, elemental, and spatial variability from source (proximal) to sink (distal) of Merapi basalt-andesitic stratovolcano (Java, Indonesia) to better constrain volcaniclastic mineral sorting in fluvial, aeolian, and coastal environments. Merapi volcaniclastics are products of an active volcano with an ongoing quadrennial eruption, which can provide insights to constrain Mars’ older and more recent volcaniclastics by focusing on anorthite, albite, and pyroxenes found on Mars’ crust. We collected stream sediment samples across the Opak River that connects Merapi with the Indian Ocean and acquired Ground Penetrating Radar (GPR) surveys on Parangkusumo Shoreface and a parabolic coastal sand dune. In addition to grain size separation, all collected samples were subjected to X-Ray Diffractometer (XRD) and X-Ray Fluorescence (XRF) to quantify their mineralogical and elemental composition, respectively, like the techniques used by the Curiosity rover on Mars to investigate the geochemistry and mineralogy of geological units in the Gale crater. To interpret the geochemical analysis, we applied multivariate statistical analysis based on Principal Component Analysis (PCA) and Hierarchical Clustering of Principal Component (HCPC). The quantitative assessment shows that the provenance contains pyroclastic materials dominated by plagioclase feldspars (albite and anorthite), followed by pyroxenes (augite and enstatite), similar to the findings of basalt-andesitic minerals on Mars’ Gale and Gusev Crater. Mineral sorting from Merapi volcaniclastics shows a plagioclase feldspar sorting from proximal to the proximal-medial interface, fault-influenced pyroxene sorting from medial to distal, and pyroxene sorting in the aeolian-dominated sedimentary system.