Cenozoic magmatism occurs throughout West Sulawesi, Indonesia, yet its detailed evolution remains enigmatic due mainly to the scarcity of precise dating. Here, we report new whole-rock geochemical and zircon U-Pb-Hf isotopic data of plutonic/volcanic rocks and river sediments from West Sulawesi to constrain the petrogenesis and magmatic tempo. The magmatic rocks are intermediate to felsic (SiO2 = 58.1−68.0 wt%), high-K calc-alkaline to shoshonitic (K2O = 2.2−6.0 wt%), metaluminous to weakly peraluminous, and I-type in composition. Trace element concentrations and ratios (e.g., Nb/U = 1.7−4.3 and Ti/Zr <28), along with negative zircon εHf(t) values (−17.0 to −0.4) and old crustal model ages (TDMC = 2.1−1.1 Ga), indicate a dominant magma source region from the underlying continental crystalline basement. U-Pb dating on zircons from ten magmatic rocks yielded weighted mean 206Pb/238U ages of 7.2−6.1 Ma, best representing the crystallization ages of host magmas, further consistent with the prominent age peaks (7.3−6.3 Ma) defined by detrital zircons from four sedimentary samples. Our new data, combined with available results, allow the identification of a noticeable climax of magmatism (flare-up) at ca. 7−6 Ma, forming a continuous magmatic belt throughout West Sulawesi. Given the absence of contemporaneous subduction and the coincidence of incipient opening of the South Banda Basin during ca. 7.15−6.5 Ma, the Late Miocene magmatic flare-up in West Sulawesi and coeval regional extension in eastern Indonesia are attributed to a resumed episode of Banda slab rollback.
A Late Miocene magmatic flare-up in West Sulawesi triggered by Banda slab rollback
- Share Icon Share
- Search Site
Xiaoran Zhang, Chia-Yu Tien, Sun-Lin Chung, Adi Maulana, Musri Mawaleda, Mei-Fei Chu, Hao-Yang Lee; A Late Miocene magmatic flare-up in West Sulawesi triggered by Banda slab rollback. GSA Bulletin doi: https://doi.org/10.1130/B35534.1
Download citation file: