Porphyry copper exploration
The Copperstone Project
Discovering porphyry copper in northern Sweden
The Copperstone project (100% owned by Copperstone Resources) is located approximately 50km southeast of Arvidsjaur and 700km north of Stockholm in northern Sweden in a place we call The Copperstone Project Area. Geologically the project is hosted within volcanogenic supracrustal rocks of Paleoproterozoic age bound regionally by voluminous crystalline granite intrusions which constitute the bedrock of the Fennoscandian Shield
This undulating afforested terrain has been eroded in more recent times through repeated glacial advances and today is largely mantled by unconsolidated sediments of Quaternary age.
The project area in Granliden also lies some 15-20km north of the famous ENE-WSW trending Skellefte-field region that hosts more than twenty (20) volcanogenic massive sulphide ore bodies which are either being mined or were mined previously, making this one of Sweden’s major base-precious metal ore producing belts.
Identifying a copper porphyry target in Arvidsjaur Kommun
Extensive historical data from this project shows widespread Cu, Au and Zn values in sulphide veins. These veins are broadly coincident with alteration styles and structural features characteristic of porphyry mineralising systems such as hydrothermal breccia and phyllic alteration.
Since the mid 2010’s, Copperstone has with increased activity explored the vast (8,000ha) property and try and unlock its true potential. Early 2017, a first systematic deep drilling campaign were conducted, and based on the results in combination with 50 year exploration data, two ground geophysical programmes (ground magnetics and Natural Source Audio Magnetotellurics – NSAMT) were implemented covering a large portion of the project area. The result was the identification of a large magnetic anomaly partially enveloped by a well-defined zone of elevated conductivity. The central magnetic anomaly was interpreted to represent an intrusive (possibly with elevated magnetic values due to alteration processes associated with mineralisation).
This anomaly is partly enveloped by a zone of conductivity interpreted to represent an alteration style that is common in porphyry copper systems (advanced argillic alteration). The identification of these geophysical anomalies and their spatial relationship to each other provided a high-quality drill target that corresponded to the genetic model for a Cu porphyry target.
The 2018 Drilling campaign
Encouraged by these results the exploration team embarked on a drilling campaign in January 2018 aimed at testing this feature. Approximately 7 600 m of diamond drilling was implemented in holes of roughly 700m each (subject to change as dictated by the outcome of the drilling). The campaign was a success and both Mineral Resources and Exploration Targets were increased significantly. (Please refer to Press Release December 20, 2018 and Mineral Resources).
Pictures from The Copperstone Project