Skip to Main Content
Skip Nav Destination

Detrital zircon U-Pb geochronology can make an extremely valuable contribution to provenance studies and paleogeographic reconstructions, but the technique cannot distinguish grains with similar ages derived from different sources. Hafnium isotope analysis of zircon crystals combined with U-Pb dating can help make such distinctions. Five Paleogene formations in West Java have U-Pb age populations of 80–50 Ma (Late Cretaceous–Paleogene), 145–74 Ma (Cretaceous), 298–202 Ma (Permian–Triassic), 653–480 Ma (mid-Neoproterozoic–latest Cambrian), and 1290–723 Ma (late Mesoproterozoic–early Neoproterozoic). Hf-isotopes have been analyzed for 311 zircons from these formations. Differences in zircon U-Pb age and Hf-isotope populations reflect changing sources with time. Late Cretaceous and Paleogene zircons are interpreted as having been derived from two temporally discrete volcanic arcs in Java and West Sulawesi, respectively. The Java arc was active before micro-continent collision, and the W Sulawesi arc developed later, on newly accreted crust at the SE Sundaland margin. The collision age is estimated to be ca. 80 Ma. U-Pb age and 176Hf/177Hfi characteristics allow a distinction to be made between Cretaceous granitic and volcanic arc sources. Zircons that are older than ca. 80 Ma have a continental Sundaland provenance. Mid-Cretaceous zircons in all upper Eocene and lower Oligocene formations were derived from granites of the Schwaner Mountains of SW Borneo. Permian–Triassic zircons were derived predominantly from granites in the SE Asian Tin Belt. 176Hf/177Hfi ratios permit distinction between Tin Belt granites in the Main Range and Eastern Provinces, and indicate that only the lower Oligocene Cijengkol Formation contains significant input from the Main Range Province, suggesting a partial change in drainage pattern. Older zircon ages are more difficult to interpret but probably record contributions from allochthonous basement and sedimentary rocks that were deposited prior to rifting of continental blocks from Gondwana in the early Mesozoic.

You do not currently have access to this chapter.

Figures & Tables




Citing Books via

Related Book Content
Close Modal

or Create an Account

Close Modal
Close Modal