1956 Peko Geological report Part II Geology of the East Peko Leases

Abstract

The sediments at East Peko are interbedded grey-wackes, fine sandstone and shales with many lenses of grit and breccia. The occurrence of many small discrete lenses of grit of fine breccia is the outstanding feature of the East Peko sedimentation. These lenses are mineralised to various degrees, the larger more completely replaced beds constituting the potential orebodies. The emplacement of at least some of the quartz-hematite rock is idependent of the breccia beds, and similar in character to the emplacement of vein quartz. The East Peko sediments are part of the north limb of a west pitching anticline; the general horizon of the breccia lenses trends east-west across the lenses, disturbed only by faulting and minor flexures. The nature of the sidimentary host rocks is such that the pitch of the orebodies is unpredictable. Anomalies 3, 4 and 5 are possibly of shallow seated origin but anomaly 2 is regarded as stemming from a quartz magnetite mass which could extend to reasonable depth. The magnetite anomalies are not directly related to sulphide mineralisation and possibly breccia host rocks could be replaced by sulphides to ore grade without magnetite or only sufficiently so that no anomaly or only a low order one is present. Conclusions are as follows; The magnetic anomalies on the East Peko leases are due to breccia lenses which have been replaced and mineralised with quartz-magnetite. They occur at the same general stratigraphic horizon. Anomaly 2 is of moderate size and offers a fair ore potential. The potential of the remaining anomalies is probably somewhat less and would perhaps compare unfavourably with some other propects on the field. Although East Peko has the advantage of proximity to the established mine it is thought that large exploration expenditure should not be continued without attention to the merits of prospects elsewhere. Due to survey error, two of the four anomalies remain untested by the drilling so far completed and further incentive such as favourable indications in anomalies 2 or 5 would be required before completing these tests is fully justified.