Proposed Title 1: - Queen's University

1696 Ma - 1715 Ma from pre-ore sericite in altered schist at the Nabarlek deposit to be
related to resetting during intrusion of the Oenpelli dolerite at 1720 Ma.
The 1601±98 Ma model age of Gn 1 galena (Fig. 4.13A) from the Coronation Hill
deposit is coincident with formation of unconformity-related U mineralization in the
Kombolgie Basin (Fig. 4.16; e.g. Page et al., 1980; Riley et al., 1980; Maas, 1989; Polito et
al., 2004). This timing is coincident with Mesoproterozoic compressional tectonism and
metamorphism during the early Isan Orogen (1600 Ma - 1580 Ma) in northern Australia
(Hand, 2006). Peak Isan Orogen (MacCready et al., 1998) is recorded by alteration of
uraninite at ca. 1500 Ma (Fig. 4.16), which deformed the McArthur Basin (Page and Bell,
1986; Connors and Page, 1995). This event is followed by fault reactivation at ca. 1400 Ma
(Figs. 4.13B, 4.16) and is attributed to deformation related to post-peak Isan exhumation
and crustal extension (Fig. 4.16, Spikings et al., 2001). Similar U-Pb ages from Jabiluka
uraninite of 1473±40 Ma (Ludwig et al., 1985) and 1400 Ma from Nabarlek (Polito et al.
2004) are interpreted to be related to this late alteration event.
An alteration event at ca. 1300 Ma (Fig. 4.16) records widespread intrusive activity
within the Pine Creek Orogen. These events correlate with the intrusion of the
Maningkorrirr phonolitic dikes and the Derim Derim Dolerite at ca. 1316±40 and 1324±4
Ma, respectively (Sweet et al., 1999). Extensive alteration between 1200 Ma - 1250 Ma
(Fig. 4.16) corresponds to tectonic activity during the Proterozoic Australia assembly as an
early component of Rodinia, involving the amalgamation of West and North Australian
cratons, followed by collision with the South Australian craton (Myers et al., 1996). At ca.
1140 Ma (Fig. 4.16) Australia and Laurentia amalgamated during the Grenville Orogen
183