1988 Annual report Black Rock prospect.

Abstract

Geochemistry - Reconnaissance over the area showed there was limited exposure but that the Quaternary cover concealed a sequence of massive sandstones and siltstone of the Carraman Formation. The limited exposure indicated an undulatory nature to the beds. Two small (3 to 5 metres long) jasper-hematite bodies crop out north-west of the Black Rock workings, one of which has been tested by drilling (see previous section). There is a large amount of quartz and sandstone float and nearly all the area was suitable for lag sampling (Carver et. al., 1987) which was carried out at 200 x 25 metre spacing. A total of 222 samples were collected and analysed for gold (to ppb levels), copper and bismuth Results, plotted on Plans 4952, 4952/1, 4952/2 were uniformly low except for two single sample anomalies with no corresponding high Bi or Cu values. One of these numbers 408388; 199 ppb Au) was however taken near the road, suggesting probable contamination. Geophysics - The Black Rock prospect is included in an area flown by Aerodata for magnetics and radiometrics. Line spacing was 200 m and flight height 60 m. Results from this survey have been processed and interpreted by Aerodata. There is no indication of any obvious magnetic targets within the Black Rock block, but several prominent lineaments, that are spatially associated with historic workings nearby, pass through the area. There are also a couple of broad uranium/thorium anomalies, the main one being to the north of the Black Cat mine and trending north-north-east. Conclusions and Recommendations - It will be necessary to take follow up soil samples across this area to try and delineate anomalous zones. At present the lag results have produced a random pattern with no strong trends appearing, the copper and bismuth values being little more than background across the area.