The Proterozoic Davenport province, central Australia: regional geology and geochronology

Abstract

The Davenport province forms the southern part of the Tennant Creek Inlier and lies to the north of the Arunta Inlier. The oldest rocks exposed are turbidites and minor 1880-1870 Ma old felsic volcanics of the Warramunga Group. These were folded, probably during the Barramundi Orogeny, and intruded by granite before being overlain by the Hatches Creek Group, a sequence up to 10 000 m or more thick of fluvial to shallow marine sedimentary and bimodal volcanic rocks. A rift-sag model of basin development involving crustal extension in an intracratonic setting is suggested for this group. Interpretation of U-Pb zircon data for felsic volcanics in the lower part of the Hatches Creek Group is hampered by problems of ancient Pb inheritance, but a preferred crystallization age of 1820-1810 Ma is indicated. Two episodes of upright concentric folding, about NW-SE- and NE-SW-trending axes, preceded emplacement of granite at ∼ 1660 Ma or earlier. Rb-Sr whole-rock data for felsic volcanics from the Hatches Creek Group are tentatively interpreted to indicate a region-wide hydrothermal alteration event at 1645 ± 44 Ma; this alteration may have been associated locally with W, Cu, Bi and Mo mineralization.