Dateline Confirms Mantle-Derived REE System at Colosseum, Launches Major Drill Program

Integrated Geophysical and Geochemical Breakthrough

Dateline Resources Limited (ASX: DTR) has unveiled a significant advancement in its exploration of the Colosseum Gold-REE Project in California. By combining multiple high-resolution geophysical surveys; including gravity, magnetics, radiometrics, induced polarisation, and magneto-tellurics; with detailed geological mapping and surface geochemistry, the company has achieved an unprecedented clarity in identifying rare earth element (REE) targets associated with carbonatite mineralisation.

This integrated approach has revealed three distinct target zones exhibiting coincident anomalies across different survey methods, a hallmark of a coherent carbonatite system. Notably, the first drillhole of the recent program, RC25-038, intersected anomalous mantle-derived REEs, confirming the presence of a deep-seated alkaline-carbonatite system analogous to the nearby Mountain Pass mine, one of the world’s most significant REE deposits.

High-Priority Targets and Drilling Strategy

The standout target, known as the Clark Mountain Fault Zone (Target 1), extends approximately 1.2 kilometres and is characterised by overlapping geophysical signatures: conductive and chargeable materials at depth, elevated potassium and thorium radiometrics, and a gravity anomaly consistent with a dense carbonatite intrusion. The RC25-038 hole intersected REE-bearing rock at around 40 metres depth on the edge of this target, with evidence that the mineralised zone widens with depth.

Target 2, the Eastern Gravity High, presents a strong gravity anomaly with resistive rock at depth, while Target 3 (the 2200N anomaly) remains under further evaluation. To thoroughly test these zones, Dateline has approved a 12-hole diamond drilling program designed to reach depths beyond 750 metres, aiming to intersect the core of the carbonatite bodies responsible for the geophysical signals.

Geochemical Fingerprints and System Integrity

Laboratory assays from RC25-038 reveal a geochemical fingerprint rich in barium, strontium, calcium, phosphorus, thorium, and uranium, elements diagnostic of alkaline-carbonatite systems. The absence of a negative europium anomaly in the lanthanide distribution further supports a mantle-derived source. Importantly, surface sampling shows no elevated oxidised sulphur species, suggesting the sulphide mineralisation remains largely intact and unweathered, increasing the likelihood that the primary REE mineralisation is preserved at depth.

Additional major element analysis indicates calcium is hosted predominantly in carbonate minerals such as dolomite and ankerite, consistent with hydrothermal alteration typical of carbonatite intrusions. This geochemical and geophysical coherence strengthens the case for a significant, preserved REE system beneath the Colosseum project area.

Project Outlook and Strategic Implications

The Colosseum Project already boasts a JORC-compliant gold resource of 27.1 million tonnes at 1.26 grams per tonne gold, equating to 1.1 million ounces, with over two-thirds classified as measured and indicated. Previous economic assessments indicated a net present value of US$550 million and an internal rate of return of 61% at a gold price of US$2,900 per ounce. The addition of a confirmed REE carbonatite system adds a compelling new dimension to the project’s strategic value, especially given the proximity to the Mountain Pass rare earth mine and the growing global demand for critical minerals.

Dateline’s Managing Director, Stephen Baghdadi, emphasised the confidence gained from the integrated datasets and the importance of the initial drill results. The upcoming diamond drilling program is poised to test the core of the carbonatite system and potentially unlock a new rare earth resource alongside the existing gold assets.