Mineral age dating
Drill cutting samples (2 m interval) were analysed for Au, Cu, Pb, Zn and As, but the results were not deemed significant at the time (Gerakiteys 1996).
In the context of an advanced-argillic alteration system that may host high-sulfidation-style epithermal mineralisation however, these results and in particular the coherent anomalous arsenic results are now considered to be significant as an indicator to possible sites of nearby concealed mineralisation (e.g. Investigator Resources has continued to refine a model for associated Cu–Au porphyry mineralisation at depth.
The age of crystallisation was interpreted from incremental heating plateau ages, defined as a sequence of two or more steps corresponding to a least 50% of the total Ar data (Table 1) implies that these rocks cooled to temperatures below ~350 °C shortly after the Kimban Orogeny (1730–1690 Ma), as revealed by the muscovite cooling ages of c.
Muscovite has a nominal closure temperature of ~350 °C (Mc Dougall and Harrison 1999).A summary of the samples and the minerals that were dated is given in Table 1.Full descriptions of the samples are provided in Nicolson et al. All samples were sent to the Argon Geochronology Laboratory, University of Queensland, for analysis.Also, the timing of alteration and mineralisation is usually complicated by overprinting and recrystallisation during subsequent fluid and thermal events and by the lack of dateable minerals that formed during the primary phase of mineralisation.Evidence in support of the model is significant, however, as confirmation of both the rare preservation of an ancient epithermal system and the regional prospectivity for this style of mineralisation.
Search for mineral age dating:
The dating of alunite from an area of advanced argillic alteration at Nankivel Hill provides new data on the timing of hydrothermal fluid activity that links with the c. Initial surface geochemistry identified anomalous concentrations of As±Au–Ag–Pb–Cu on the northern margin of brecciated and silicified carbonate metasedimentary rocks, correlated with Katunga Dolomite of Paleoproterozoic Hutchison Group (Coutts et al. The anomalous area was referred to as the Nankivel Dam prospect and the main outcrop of siliceous breccia was later informally named Nankivel Hill (Figs 1, 2).