Geophysics Clause Samples
Geophysics. Numerous geophysical surveys have been completed during the course of activity at P▇▇▇▇▇. These include regional and detailed surveys. Regional surveys include gravity and aeromagnetics. Detailed surveys run were mostly electromagnetic in nature and include IP, EM, MT, and CSAMT surveys. A brief summary includes:
1) Airborne EM and magnetics by the USGS at ¼ mile spacing throughout much of the G▇▇▇▇▇▇▇ Trend.
2) Ground based magnetics covering the CX zone completed in 1970 by the Cordex Syndicate.
3) Regional gravity surveys, both public and private, compiled by Homestake Mining Company in 1997.
4) Ground-based magnetic survey at the north edge of the MAG pit completed in 1998 by Homestake Mining Company.
5) Several generations of AMT (EM, IP, CSAMT) completed by P▇▇▇▇▇ Mining Company.
6) Several CSAMT lines completed by Homestake Mining Company in 1998 to 2000.
7) Several EM lines completed by Homestake Mining company in 2000 Technical reports and data sets are available for these surveys. No interpretive reports have been located. The geophysical surveys previously completed at the project have not been utilized by Atna as part of its exploration efforts to define mineralization associated with the CX and Range Front mineral zones.
Geophysics. To date no airborne EM survey (or other airborne geophysical survey for that matter) has been conducted across the Project. The opportunity exists to identify targets across the prospective 16km strike horizon for VMS which have not been identified or evaluated. The two most useful ground geophysical surveys appear to be (i) a ground electromagnetic (EM-37) survey completed for Noranda in the early 1990’s and (ii) and an induced polarization/resistivity survey completed for York Harbour Metals Inc. in 2022. The survey was carried out in 1990 by Quantech Consulting on behalf of Noranda Exploration Company with a total of 29.1 km of EM-37 geophysical surveying from four loops. Some of the electromagnetic (EM) anomalies in the mine area that lie near the lower basalt to upper basalt contact probably correspond to the massive and semi-massive sulphide mineralisation in that area. Similar conductors occur along the lower basalt to upper basalt contact on the west side of the syncline. Induced polarization (IP) and resistivity surveys were completed by Eastern Geophysics Ltd. in 2022. In the mine area, anomalous IP chargeability appears to correspond to both the area of the massive sulphide zones as well as to the footwall rocks lying to the east. The chargeability response in the footwall rocks may be due to ▇▇▇▇▇▇▇▇ and disseminated sulphide mineralisation within a footwall alteration zone that formed as a result of hydrothermal fluid flow beneath the ancient seafloor.
Geophysics. In 1974 and again in 1999/2000, the Ontario government flew airborne magnetic and electromagnetic surveys over areas which include the present ▇▇▇▇▇▇ property. Magnetic maps from the two different surveys show similar features: an overall easterly trending grain, with mostly elliptical (east-trending) highs and lows (Fig. 7; ODM, 1975; Ontario Geological Survey, 2000a; b). ▇▇▇▇▇▇ (1992) notes that the generally higher magnetic signatures in the southern part of ▇▇▇▇▇▇ Township correspond to a mapped sequence of iron-rich tholeiitic basalts. An intense, subcircular, 500 m wide magnetic high is apparent on both surveys, located in the north-central part of the ▇▇▇▇▇▇ property (Fig. 7), and recently tested by Warrior (Section 13). No significant discrete conductors were identified on either airborne survey. The map of apparent conductance shows an anomaly coincident with Whitefish Lake in the northeastern part of the property, along the Montreal River fault system. This anomaly is proximal to several surficial conductors, and is not considered by the authors to be of exploration significance.