Search

Copyright of Mineral Resources Management / Gospodarka Surowcami Mineralnymi is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mineral Resources Management / Gospodarka Surowcami Mineralnymi is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Situated in the heart of the Indonesian archipelago, Sulawesi records well-developed Cenozoic magmatism, yet its Cretaceous magmatic evolution remains enigmatic. Here, we report new U-Pb-Hf isotopic data of detrital zircons from West Sulawesi, Indonesia to constrain its Cretaceous to Eocene magmatic tempo. Detrital zircons aged at ca. 105-80 Ma and ca. 70-45 Ma occur as the most dominant age populations and show high positive εHf(t) values, indicating derivation from juvenile sources with limited continental crustal contamination. Our new data, combined with available results, support the existence of an Andean-type continental margin in West Sulawesi during mid-Cretaceous to early Eocene times. Importantly, the magmatic tempo of West Sulawesi is also consistent with those of southern Lhasa (Tibet) and Sumatra (Indonesia), but contrasts with those of Paleo-Pacific subduction-related arcs in SE China, SE Vietnam, East Malaysia, and NW Borneo. Therefore, we put forward that West Sulawesi may be the southeasternmost component of the Neo-Tethyan arc system that spreads over 7500 km, from southern Tibet to SE Sundaland. Such a huge arc system with concurrent magmatic flare-ups and lulls in South Asia may have played a significant role in global-scale plate reorganization. [ABSTRACT FROM AUTHOR]

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 UPb- 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 calcalkaline 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 eHf(t) values (-17.0 to -0.4) and old crustal model ages (TDM C = 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. [ABSTRACT FROM AUTHOR]