Mineral age dating strolldating com
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.
Other mineralisation has been linked to this event, including epithermal-style precious metal, lead–zinc, tin and copper occurrences along the southern margin of the Gawler Range Volcanics, on northern Eyre Peninsula. The result confirms the preservation of a Mesoproterozoic epithermal mineral system and adds support for exploration models that anticipate remnants of extensive, interrelated and varied epithermal mineralisation associated with the southern extent of the Gawler Range Volcanics.
The timing and relationship of these apparently disparate mineral occurrences, however, remain poorly constrained. During mineral exploration by Aberfoyle Resources in 1991, siliceous breccia in low hills south of Nankivel Dam and 4.5 km WNW of Peterlumbo Hill, northern Eyre Peninsula, was recognised as evidence of shallow crustal hydrothermal activity, most probably related to igneous activity during eruption of the Gawler Range Volcanics (Coutts et al. The observation raised the potential for epithermal-style gold mineralisation.
Subsequently, these rocks were subjected to high-sulfidation style epithermal alteration.
The timing of this alteration is suggested to be c.
1590 Ma volcanic and plutonic event that formed the silicic large igneous province on the Gawler Craton, but this has proved to be difficult to confirm by direct dating methods.
Total mineral resource at the Paris deposit is estimated at 9.3 Mt at 139 g/t Ag and 0.6% Pb for 42 Moz contained silver and 55 kt contained lead at a cutoff of 50 g/t Ag (Investigator Resources 2017a).
Consequently, muscovite from samples of high-grade metamorphic rocks of Warrow Quartzite both close to and distal to the alteration system were also analysed.
Muscovite has a nominal closure temperature of ~350 °C (Mc Dougall and Harrison 1999).
In reality, the ‘closure temperature’ of a mineral to Ar diffusion is more likely a temperature range, however, this range depends upon factors such as the rate of cooling, the grain size and also upon the degree of crystallinity of the mineral (e.g. Ar mineral ages can be variously interpreted as the age of mineral crystallisation, the age of cooling through a nominal closure temperature, or the age of mineral alteration.
Choosing between these alternative interpretations, particularly for results from fluid alteration systems, can be assisted by comparison of results with Ar dating of samples from outside the alteration system.