NT phosphate 1970 drilling program AP 1874 (Alroy area)

Abstract

In the 1968 drilling program a promising phosphatic zone was located in scout hole A2-2A in the Alroy area. Between 21/7/70 and 9/8/70 fifteen holes were drilled in the vicinity of A2-2A in an attempt to define the broad limits of the phosphate zone, the holes were drilled on a grid pattern using two mile spacings. Encouraging phosphate values were obtained in A-10-70 and A-12-70. In A-12-70 however the phosphatic section is carbonate rich. Area No. 1 (Alroy): This area is controlled by two holes:- hole A2-2A drilled in 1968 by Continental Oil and hole A-10-70 drilled by PMI in the 1970 drilling program. (Hole A2-2A has a phosphatic interval extending from 60 ft. to 80 ft. averaging 10% P2O5. Six feet of this, from 60 to 66 ft averages 14.57%. Hole A- 10-70 has a phosphatic interval of 21 ft. extending from 53 to 74 ft. averaging 12% P2O5. The best part of this is 15 ft. from 57 ft. to 72 ft. averaging 15.5%. The reserves were calculated using the above two holes. The holes were estimated to control an area four miles long and 1.75 miles wide with the long axis through the two drill holes. Average thickness over the area is 10.5 ft. and average grade (weighted) is 15.3%. Using a value of 20 cubic feet equal to one short ton the reserves of average 15.3 % are 100 million tons. Area No. 2 (Buchan Dam): This area is controlled by one hole A-12-70 which contains a 20 ft. phosphatic interval from 40 to 60 feet averaging 25% P2O5 with values up to 32.6% P2O5. This gives an inferred reserve of 88 milIion short tons of 25%. The phosphatic interval in area no. I varies from weakly calcareous to non calcareous. However in area two the phosphatic interval is a calcilutite. Note also that area no. 1 has been closed off by drilling whereas area no. 2 is open.