Castle discovers anomalous gold corridor at Beasley Creek
Washington state-focused explorer Castle Minerals successfully unearthed a large north-northwest trending anomalous gold corridor thanks to its recently completed soil sampling campaign at the company’s 79 square kilometer property at Beasley Creek in the Pilbara District.
The soil program consisted of 480 samples with a maximum recorded value of 202 parts per billion. Several other samples had grades above 50 parts per billion gold, well above background levels. Castle says the results validate his strategy to target structural-controlled orogenic-style gold mineralization in the ancient Archean greenstone terrane.
The sampling lines, located primarily in the Beasley Central area, were positioned in an area of Archean metasediments located on the northern flanks of the intrusive Rocklea Dome metagranite complex. According to the company, the geological setting is similar to that of the Paulsens gold mine at Northern Star, 115 km to the west. Several anomalous gold values were also obtained from additional lines at Beasley West, where soil sampling was designed to test an area of strong gold anomaly from stream sediment sampling.
Soil sampling also revealed sparse anomalous values of copper, zinc, nickel and platinum which will be verified in the field and monitored as necessary. The results are also awaiting a second phase of soil reconnaissance sampling which has just been completed on the western and eastern zones in the older Archean stratigraphy and outside the presumed gold corridor.
The Beasley Creek area has been explored by several companies over the past 50 years for iron ore, diamonds, nickel, base metals and platinum group elements. Castle’s initial exploration at Beasley Creek focused on identifying paleo-placer conglomerate-style gold mineralization. Several small gold nuggets were recovered by contracted detectors near the basal conglomerate horizon of the Archean Hardey Formation over several kilometers of the approximately 16 km strike discordance. Nuggets tend to have a sub-rounded dendritic texture and a relatively high silver / gold ratio which geologists say indicates a low temperature hydrothermal formation environment.
Recent fieldwork has identified several heavily weathered quartz veins of hydrothermal origin near where the nuggets were found. These veins are found in highly weathered and sheared greenstone lithologies. The location of the nuggets seems to coincide with the location of the flush veins. To add a bit of intrigue to this, management says undocumented iron caps and quartz veins outcrop around drainages that contain anomalous gold from soil and stream samples. These outcrops exhibit sulphide textures and a green malachite stain which may indicate copper mineralization.
Bulk stream sediment sampling conducted last year by Castle showed all 47 samples collected to be anomalous for gold, with mineralization occurring in four zones over a 12 km stretch, namely Beasley West, Beasley Central, Beasley East and Beasley Far East.
Castle now has a diamond drilling program ready to go with three spaced holes targeted to improve understanding of the geology at Beasley Creek. Holes will be drilled in the lower unit of the Hardey Formation and will be drilled through basal conglomerate and underlying unconformity in older Archean greenstone. Castle Minerals was successful in applying for co-funding for these drill holes as part of the latest round of the Geological Survey of Western Australia Exploration Incentive Scheme.
The Pilbara has seen some mineral resurgence lately, particularly in the gold sector following the discovery of Hemi by ASX-listed De Gray Mining in late 2019. While Beasley Creek is a proposition gold exploration at a relatively early stage, the possibility of a material gold discovery is validated by the presence of historical work from an alluvial mining operation in the early 1990s that appears to have recovered gold in creek bed gravels in and around the mapped unconformity surface in the Beasley Central area of interest. This, along with the results of Castle’s recent exploration work, suggests the company may be on to something interesting.
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