Fluvial Transport Distance, Flatness Index
The method of Youngson and Craw (1999) seeks to quantify the transport distance of gold grains. It cannot allow for glacial movement, as ice transport doesn't change the gold much. I found this paper about the Nokomai area, and of course Glass Earth already has a permit application there. But a part of the discussion is very interesting, and should apply to Drybread.
http://www.nzpam.govt.nz/cms/pdf-lib...e/youngson.pdf
Quote:
Transport distance estimates 2000 New Zealand Minerals & Mining Conference Proceedings • 29-31 October 2000
Rounding, flattening and folding of detrital gold preserves a cumulative record of the deformation it undergoes during transport from a primary source to the ultimate site of deposition. Particle flattening is particularly important, because it progressively lowers the surface area-to-volume ratio of gold which, in turn, enhances the entrainability of particles in a given current. On-going flattening thus allows gold particles to be progressively transported to lower-energy parts of the fluvial system (Youngson & Craw 1999).
Consequently, there is a predictable relationship between the maximum flatness of gold particles and maximum transport distance in gravel bed-load rivers. This has been quantified for the Arrow-Kawarau-Clutha River system in Otago, where the gold sources are well-constrained (Youngson 1998; Youngson & Craw 1999), and similar relationships have been established elsewhere (Herail et al. 1990, Knight et al. 1994).
Fluvial transport distance estimates for Nevis and Nokomai gold (Table 1) were made using the method of Youngson & Craw (1999). This method relates fluvial transport distance to the maximum flatness index for gold particles in a particular sample [F.I.=(a+b)/2c, where a, b, and c are the mutually perpendicular long, intermediate and short axes of the particle]. The method cannot account for any glacial transport, however, as little or no flattening of gold occurs during such transport.
The small proportion of relatively more deformed gold particles in some Nevis samples has higher maximum flatness index (18–25) than that for the bulk of the gold (<15) in those samples (Table 1). Maximum transport distance estimates of 20–30 km for the more flattened gold is consistently greater than the <10–20 km estimates for the bulk of the Nevis gold (Table 1), and supports more distant primary sources and/or a recycling history for the more deformed gold. Conversely, the shorter transport distance estimates for the bulk of the Nevis gold are compatible with our inference of primary sources within the western tributaries of the Nevis. Similarly, low maximum flatness index (<15) and short (<10–20 km) maximum transport distance estimates for a-phase Au-Ag-Hg alloy in all samples upstream of the alluvial plain in the lower Nokomai (Table 1) support our inference of primary sources in the upper eastern tributaries of the Nokomai.
Furthermore, 15–25 km estimates for α-phase Au-Ag-Hg alloy within the alluvial plain are also consistent with derivation from such sources. The 25–40 km fluvial transport estimates for Au-Ag alloy in the abandoned channel and alluvial plain in the lower Nokomai are enigmatic, firstly because the Nokomai valley is only about 20 km in length (Figure 3), and secondly because detrital Au-Ag alloy has not been found elsewhere within the catchment. The fluvial transport distance estimates require either considerable fluvial recycling of Au-Ag alloy within the Nokomai, or a former connection with an Au-Ag alloy source outside the present Nokomai catchment. The absence of Au-Ag alloy elsewhere in the Nokomai does not support the possibility of local Au-Ag sources or recycling within the catchment.
Amazing. Just a quick inspection of the gold particles and a lab analysis can reveal that some are recycled, and some are simply weathered out of rock nearby, or several kilometres away. The maths up there doesn't look too hard either.
Fluvial Transport Distance, Flatness Index
The chunkiest of the gold grains from Drybread might have an F.I. of under 10, so if similar to the Nokomai area, they will have been moved less than 10km.
Glass Earth holds permit EP53182 around Drybread, and about 6km futher north is the boundary of a big permit application from them, PP53297. Others have moved in with their own permits in the area. Southwest of Drybread is a smaller mining permit MP41748 (Matakanui), now owned by Hawkeswood Mining Ltd. It's due to terminate in 2013. Andrew Hawkeswood has 30 staff, some in Auckland in other operations.
http://www.nzrallychampionship.co.nz...p-in-wairarapa