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Gold/Mining/Energy : Prosperity Goldfields Corp -- Ignore unavailable to you. Want to Upgrade?

To: Natedog who wrote (567)	8/1/2011 1:45:25 AM
From: E. Charters	Respond to of 906

orogenic my lad. not epi. I will fight to the death on that. EC<:-} "The goldfields originated from the weathering and erosion of early Cretaceous, discordant mesothermal quartz veins, and the light grey color of the matrix of the White Channel Gravel is due mainly to weathering and diagenetic alteration by groundwater flow. The concentration of placer gold is related to a hierarchy of physical scales: at the lithofacies scale (metres), bed roughness determined sites of gold deposition; at the element scale (tens of metres), gravel bars were preferentially enriched in gold; at the reach scale (hundreds of metres), stream gradient was an important factor; at the system scale (hundreds of km), braided river environments transported large amounts of gold; and at the sequence scale (thousands of km), economic placers formed initially in the high-level White Channel Gravel and later in the intermediate-level and low-level gravel. The White Channel strath is interpreted as an erosional ‘tectonic’ terrace that formed during isostatic uplift and under conditions of dynamic equilibrium. The high-level White Channel Gravel and Klondike Gravel are interpreted as a depositional ‘climatic’ terrace that formed during a reversal in the tectonically induced downcutting, which is attributed to the initial and most extensive of the pre-Reid glaciations (3 Ma) in the Yukon. The intermediate-level gravel is interpreted as minor erosional ‘complex response’ terraces that formed during static equilibrium when there were pauses in valley-floor degradation, which are attributed to the subsequent and less extensive pre-Reid glaciations. The low-level gravel formed also during valley-floor degradation and may represent a return to dynamic equilibrium conditions. Hence, the dominant forcing mechanisms controlling the evolution of the goldfields were isostatically compensated exhumation and climatic change related to the repeated glaciation of the Yukon. In addition, the lowering of baselevel from high-level, to intermediate-level and finally to low-level gravel was accompanied by a decrease in accommodation space (as indicated by a decrease in gravel thickness), which resulted in an increase in the concentration of the placer gold."

To: Natedog who wrote (567)	8/1/2011 2:01:14 AM
From: E. Charters	Read Replies (1) \| Respond to of 906

LODE DEPOSITS There are over 60 occurrences and prospects of lode gold throughout the study area (Map 2, in pocket), and almost all of these are vein deposits (Yukon MINFILE, 2003). Gold-bearing quartz veins in the Klondike River and Indian River drainage basins, which are thought to be the main source of gold for the Klondike goldfields (McConnell, 1905b, 1907; Knight et. al., 1994, 1999), were studied by Hoyman (1990) and Rushton (1991). Rushton (1991) and Rushton et al. (1993) concluded that the veins are mesothermal in origin and were emplaced in the earliest Cretaceous (Plate 1b). Goldfarb et al. (2000) and Goldfarb et al. (2001) classified these veins as ‘orogenic Au deposits’ and suggested that they may be part of the intrusion-related gold deposits of the Tintina Gold Belt (see British Columbia and Yukon Chamber of Mines, 2000). According to Goldfarb et al. (2001), Kula-Farallon Plate convergence initiated gold veining along western North America at ~180 Ma, which spread southward from Alaska, through central Yukon (culminating about 140 Ma in the Klondike) and into British Columbia. Approximately 40 kg (1300 oz) of gold was produced from these veins at the Lone Star Mine (Yukon MINFILE, 1997). Ash (2001) recently proposed that the main source of gold for the Klondike goldfields was gold-quartz veins hosted by the Slide Mountain Terrane, which is now mostly eroded and preserved as isolated klippen above Yukon-Tanana Terrane basement rocks (Fig. 3). The source of gold in the Klondike goldfields is discussed further in the next section: General Stratigraphy, Sedimentology and Placer Formation.