Major New IP Anomalies At Windfall Target

COEUR D'ALENE, ID - Timberline Resources Corporation reported results of an Induced Polarization/Resistivity (IP) survey at its 100%-controlled Eureka Gold Project in Nevada. The 2021 IP survey focused on the Windfall Trend in the northeast part of the property. The data have identified two major structural zones that appear to control strong chargeability anomalies that could be linked to the extensive gold and polymetallic systems in this part of the project.

Between 1975 and the early 1980s, the Windfall Mine produced approximately 112,000 oz of gold from oxidized ore from three open pits along a 2.5-kilometer (km) trend on claims owned by Timberline. Previous drilling and rock sampling by Timberline and other operators has encountered significant gold mineralization in and around the historic pits. Zonge Geosciences, Inc. surveyed six lines of dipole-dipole IP totaling 25.2 line-km along the Windfall Trend. The 2021 IP survey complemented the 2020 IP survey, which focused on the Lookout Mountain Trend but included one line through the middle of the Windfall Trend.

The resistivity and chargeability data derived from the IP survey paint a clear picture of two parallel fault zones oriented generally north-south. These structures correspond well with existing geological mapping in the area, but the extent of the chargeable zones as well as a new target corridor to the west of historic mining are new information. IP chargeability anomalies are suggestive of the presence of sulfide minerals and/or organic carbon, both of which are commonly associated with Carlin-type gold deposits.

Steven Osterberg, Vice President Exploration, said, "We are very appreciative of the quality work by Zonge Geosciences and consulting geophysicist Jim Wright on our 2021 IP survey at Windfall. These IP anomalies at the Lookout Trend and the Windfall Trend are very large cohesive targets. They occur in similar settings, both occupying large-scale structural troughs and having significant mineralization flanking the chargeability highs on both the east and west. These large-scale geophysical anomalies may indicate significant sulfide mineralization associated with these large structures, demonstrating potential drivers or roots to the gold systems of which we are already aware. All of these targets reinforce our view of the huge potential of the Eureka Project, and we look forward to the remainder of our 2021 drill program, which is set to recommence in October."

Resistivity data at Windfall reveals consistent patterns that facilitate mapping of rock types, dip attitudes, and structures. The major structures in this area are termed the Windfall Structural Zone (WSZ) and the Windfall East Structural Zone (WEZ), and they are continuous for at least 2.5km along strike. The WSZ is interpreted as dipping steeply to the east and it correlates well with the historic gold mining trend. It separates steeply east-dipping sedimentary units to the west, from moderately east-dipping rocks to the east. Dolomite of the Hamburg Dolomite (Ch) and Eldorado Dolomite (Ce) formations is among the most resistive rocks in the district, and the Prospect Mountain (Cpm) and Eureka Quartzite (Oe) are also highly resistive. This is opposed to the Dunderberg Shale (Cd) and other thinly bedded units, which show up as less resistive.

The WEZ correlates well with the previously mapped Hoosac Fault, which generally has a westward dip, but the WEZ is also sometimes associated with a near-flat lying thrust or detachment structure in the northern part of the district. A number of significant historic gold, silver, and base metal occurrences are aligned with the WEZ and the

A strong chargeability anomaly occurs parallel to and between the WSZ and the WEZ in an apparent structural trough. The chargeability feature is best developed in the southern part of the survey area, but it has continuity to the north, though tending to narrow on the more northerly lines. This central anomaly is up to 300 meters (m) wide and extends to within 100m of the surface locally within its +3km footprint. A second chargeability anomaly occurs immediately east of the WEZ where Timberline geologists have noted significant hydrothermal alteration in numerous historic prospects. These chargeability anomalies are of a character that is suggestive of unoxidized sulfide minerals at depth.

Another strong chargeability anomaly occurs in the northwest corner of the survey area where little modern exploration has been conducted. The magnitude of the anomaly is very strong and measures up to 400m wide. This chargeable feature is apparently hosted by the Eldorado Dolomite and is interpreted to lie within 230m of the surface. There is another weaker chargeability anomaly in this northwestern area to the west of the WSZ. This anomaly trends to the northeast and can be traced for more than 2km. It is also apparently associated with the Eldorado Dolomite, but it may be linked to an unrecognized fault or fold structure.

The Eldorado Dolomite was the primary host of the silver-gold-lead-zinc mineralization that prompted the mining boom in Eureka in the late 19th century. Timberline geologists have just begun reconnaissance mapping and sampling in the northwest part of the survey area, where the Eldorado occurs at surface and dips east towards the Windfall Trend.