SHRIMP U–Pb ANALYSES OF DETRITAL ZIRCON: A WINDOW TO UNDERSTANDING THE PALEOPROTEROZOIC DEVELOPMENT OF THE TANAMI REGION, NORTHERN AUSTRALIA

Abstract

Poorly exposed Paleoproterozoic turbiditic to shallow marine sedimentary rocks of the Tanami Basin, NT, Australia are largely the erosional products of either the ∼1.87–1.85 Hooper Orogeny and/or magmatism associated with the ∼1.87Ga Nimbuwah Event. Dating of detrital zircon from six of the principal sedimentary units shows that deposition spanned at least the period ∼1.84–1.77Ga. Collectively, the detrital zircon ages reveal a progression in provenance that is a record of the development of the orogen. The basal Dead Bullock Formation contains only zircon derived from Archean basement and no contemporaneous products of orogeny. Its deposition age is inferred to be ∼1.87–1.84Ga. Orogenic ∼1.86Ga zircon appears in the overlying Killi Killi Formation, deposited between ∼1.84–1.82Ga and persists, probably due to recycling in all overlying units except one, the Mount Charles Formation. The accepted stratigraphic position of this unit might be incorrect.