Patagonia Lithium’s seismic survey reveals deeper basement at Formentera, boosting resource potential

Seismic Survey Doubles Basement Depth at Formentera

Patagonia Lithium Ltd (ASX:PL3) has revealed that its recent passive seismic survey at the Formentera Lithium Project in Argentina has identified basement depths reaching 800 metres, effectively doubling the depth of its previous drilling program. The survey’s geophysical data, integrated with geological and drilling information, highlights a basement interface between 3,200 and 3,400 metres above sea level, which places it approximately 800 to 1,000 metres beneath the salar and aquifers. This finding significantly expands the potential volume of lithium brines hosted in the basin.

Strong Correlation Between Seismic and Drilling Data

The passive seismic survey employed Horizontal to Vertical Spectral Ratio (HVSR) and Multi-channel Analysis of Surface Waves (MASW) techniques, calibrated against existing drill holes. Executive Chairman Phillip Thomas emphasised the robust correlation between volcanic marker horizons identified in drilling and the seismic impedance contrasts detected. This alignment bolsters confidence in the geological model and is expected to heavily influence the upcoming Mineral Resource Estimate (MRE) update.

However, the deepest interpreted seismic reflector, indicating the basement, carries lower confidence due to potential contamination by low-frequency noise and the intrinsic limitations of seismic methods in distinguishing lithological boundaries. Consolidated clay-rich intervals and compact fine-grained sediments can produce seismic signatures similar to gravel packages, necessitating careful cross-referencing with drill logs.

Ongoing Pump Tests Confirm Aquifer Quality

Meanwhile, wells 2, 3, and 6 at Formentera are undergoing 72-hour pump tests with larger hoses, nearing completion and showing strong correlation with previous results and near maximum flow rates. These tests continue to validate the high porosity and permeability of the aquifers, consistent with earlier results such as the 412ppm lithium assay at Well Six and promising packer tests at Well Seven. Such positive hydraulic performance supports the project's economic viability and resource expansion potential.

Drilling Progress and Future Validation

Drilling at well JAM-26-07 has reached 434 metres and continues to intersect significant gravel intervals, potentially approaching the deeper basement reflector estimated at 500–550 metres depth. This well presents a critical opportunity to directly evaluate whether the interpreted deep seismic reflector corresponds to the true basin basement or represents another consolidated lithological package. The company plans further gamma porosity surveys and extended pump tests before incorporating these data into the next MRE update.

This step is crucial given the seismic interpretation’s qualitative nature at depth and the transition observed during drilling from coarse gravel to more consolidated fine-grained sequences around 200–220 metres. The ongoing integration of geophysics and drilling data exemplifies Patagonia Lithium’s methodical approach to refining basin architecture and resource estimates.

Expanding Resource Potential in the Lithium Triangle

The Formentera Project, located in the prolific Salar de Jama region of Jujuy Province, Argentina, is part of Patagonia Lithium’s broader portfolio, which includes the Cilon and Tomas III projects. The recent seismic results complement previous high-grade lithium assays and porosity findings, such as the 591ppm lithium recorded in drill hole JAM-24-01 and ongoing positive pump test results reported in May 2026. This momentum is underpinned by a 551,400 tonne LCE Mineral Resource Estimate released in July 2025, which is poised for revision following these new insights.

Patagonia Lithium’s strategic focus on integrating geophysical surveys with targeted drilling and hydraulic testing reflects a sophisticated exploration strategy. The company’s progress, including environmental approvals and capital raises, has been detailed in recent updates, such as the high lithium assays and $2.79m capital raise and strong packer test and environmental approval, underscoring steady advancement towards commercialisation.