Combining dissolved, suspended and bed load stream geochemistry to explore for volcanic massive sulfide deposits: Big Salmon Complex, northern British Columbia

Abstract

Exploration successes for volcanogenic massive sulfide (VMS) deposits, such as Kudz Ze Kayah, Wolverine and Fyre Lake in the Yukon–Tanana Terrane and Slide Mountain Terrane (southern Yukon Territory) have spurred interest in the correlative rocks in the Big Salmon Complex in northern British Columbia. In an effort to further the utility of multi-media stream geochemistry in exploration frontiers that are forested, heavily drift covered, or buried, the primary streams of 19 watersheds from the East Teslin Lake (National Topographic System (NTS): 104N/9, 16) and Teh Creek areas (NTS: 104O/11, 12, 13, 14) of the Big Salmon Complex were analyzed for Cu, Pb, and Zn and other parameters in the dissolved load, suspended load and bed load. Traditionally, exploration based on stream geochemistry has employed the bed load and more recently the dissolved load chemistry, but almost never the suspended load despite strong differences in the geochemical signatures of the three media. Here, we document that copper, lead, and zinc partition into the dissolved, suspended, and bed loads differently and that the magnitude of anomalies is different for each media. The adsorbing capacity of the suspended load may make it a more sensitive indicator of mineral deposits on a regional basis than either the trace-element-poor dissolved load or the bulk-rock-diluted bed load which are likely better indicators of local mineralization. It is clear that each phase contributes unique information about the distribution of elements in the watershed that could be considered in exploration models. We also show that summing standardized element concentrations and summing the sums across media appears to be an effective method to reduce the data without loss of important information. We likewise investigated the utility of calculating major element normalized enrichments for exploration and find that it is a promising approach.