Vox Geophysics' Expert Modelling Confirms High-Priority REE Target at Colosseum's 2200N

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Strengthening Domestic Critical Mineral Supply

SAN BERNARDINO, CALIFORNIA / ACCESS Newswire / September 24, 2025 / Dateline Resources Limited (ASX:DTR)(OTCQB:DTREF)(FSE:YE1) is pleased to announce that second ModEM 3D magneto-telluric (MT) inversion result has also confirmed the high-priority REE drill target on line 2200N at its 100%-owned Colosseum Gold-REE Project, California. This target was originally identified in August using Viridien's RLM-3D inversion model. The latest modelling, an independent inversion by Dr. Kate Selway of Vox Geophysics using the open-source ModEM code, produced a very similar 3D resistivity model, validating the earlier interpretation.

Highlights

• ModEM Model Review: A second 3D MT inversion model has confirmed the high priority 2200N REE target, located just north of the historical gold open pits.

• Model Consistency: The RLM-3D and new ModEM inversions produced resistivity models with very similar features, providing strong cross-validation of the target.

• Deep, Coincident Anomaly: In both models, a resistive region extends to at least ~1,000 m depth below the surface, spatially coincident with outcropping REE bearing fenite dykes (consistent with an REE bearing carbonatite source).

• Upcoming Drilling:Majors Drilling will mobilise additional rigs in coming weeks to expedite testing of this high-priority REE drill target.

• Parallel Validation Underway for Gold Targets: A second-party review is in progress to validate the six new gold breccia pipe targets identified in August 2025, strengthening confidence ahead of drill testing.

In both models, a prominent resistive anomaly is observed on line 2200N, extending from ~1,000 m depth up to surface and coincident with surface fenite dykes. Notably, this resistive body's alignment with fenite (an alteration typically haloing carbonatite intrusions) is consistent with a carbonatite source, indicating carbonatite-hosted potential for REE mineralisation at depth

Dateline's Managing Director, Stephen Baghdadi, commented:

"This new modelling, conducted by two highly skilled groups, using different analysis software and inversion modelling methods have both confirmed the exciting 2200N rare earth target, we look forward to drill testing our new REE and gold targets and adding further value for shareholders."

Figure 1: 3D MT resistivity cross-section (Line 2200N) modelled using Viridien's RLM-3D inversion. The prominent high-resistivity anomaly (blue zones) extends from ~1,000 m depth to surface beneath the area of known fenite dykes. This deep resistive body is interpreted as a potential carbonatite intrusion associated with REE mineralisation. (Vertical axis in metres; horizontal axis in metres along line.)Figure 2: 3D MT resistivity cross-section (Line 2200N) from the independent ModEM inversion by Vox Geophysics. The ModEM result reveals an almost identical resistive anomaly (Blue) in the same location and depth range as the RLM-3D model. This independent replication strongly validates the target's robustness. The consistency between the two models underscores this high-priority anomaly's carbonatite-hosted potential as an REE system.

Magneto-Telluric Inversion Modelling

The MT survey data (167 stations on 14 lines) were reprocessed by Vox Geophysics using the ModEM inversion algorithm to generate a fresh 3D resistivity model for the Colosseum Project.

Figure 3: Plan view of Colosseum claim boundary showing MT survey lines and REE bearing fenite outcrops in black diamonds.

Dr. Selway, a globally recognized expert in magneto-telluric data analysis with over 20 years of experience, holds a PhD in MT methodologies and has conducted fieldwork across diverse regions, including Antarctica, Greenland, East Africa, Australia, and the United States. Her extensive academic background includes roles at prestigious institutions such as the University of Adelaide, Yale University, Lamont-Doherty Earth Observatory, and the University of Oslo, complemented by contributions to high-profile geophysical publications.

Dr Kate Selway, Managing Director of Vox Geophysics, noted: "The two independent RLM-3D and ModEM approaches, with independent data analysis and different inversion codes, have produced resistivity models with very similar features. This cross-validation between the two independent approaches provides confidence that features consistently imaged in both models are robust and reliable."

This independent model closely mirrors the original RLM-3D model, confirming all major resistive and conductive features. Crucially, the east-west Line 2200N anomaly - previously highlighted as a zone of REE potential - appears virtually identical in both models. In each case, a broad high-resistivity zone (hundreds of metres across) rises from at least ~1 km depth to the near-surface, directly beneath outcrops of fenite dykes. The duplication of this feature by two independent inversion codes greatly reinforces confidence in its geologic significance. The spatial coincidence of a deep-seated resistive body with surface fenite alteration is a signature characteristic of carbonatite-centred REE systems, suggesting that the 2200N anomaly may represent a carbonatite intrusive source for REE mineralisation. This interpretation aligns with other geophysical evidence at Colosseum, where the 2200N target area also shows a gravity high and magnetic low pattern analogous to the nearby Mountain Pass carbonatite REE deposit (~10 km south).

Next Steps: Drilling and Exploration Strategy

Drill Testing: Dateline plans to commence drill testing of the new rare earth target on line 2200N (along with several new gold targets) in the upcoming December quarter. Diamond drilling is already underway at Colosseum, focused on infill and extensional holes in the existing gold mineral resource as part of a Bankable Feasibility Study (BFS). Drill rigs are being mobilised to site through September-October to accelerate the exploration program and fast-track the testing of newly defined targets. The 2200N anomaly, now supported by two independent 3D models and surface geological indicators, is regarded as a high-priority REE drill target and will be a key focus of the upcoming campaign.

Importantly, the area of the 2200N anomaly has seen no historical drilling. Past exploration at Colosseum was largely gold-focused and concentrated around the known breccia pipe gold outcrops, leaving the REE potential of the broader system underexplored. The newly defined 2200N target therefore represents a potential fresh discovery.

Broader Exploration Strategy: The validation of this REE target is in keeping with Dateline's dual-track strategy at Colosseum of advancing the known gold deposit toward development while unlocking new value in the project's rare earth and additional potential gold bearing breccia pipe targets. The Company's rigorous approach to data collection, now bolstered by the latest 3D MT results, is designed to de-risk drill targeting and maximize the chance of discovery. Dateline's technical team will incorporate the ModEM model insights into final drill planning for the REE targets.

MT Gold Target Review: In addition to the REE inversion validation, Dateline has initiated a secondary review of the gold-focused MT model. This review aims to independently validate the six high-priority breccia pipe targets announced in August 2025. Results from this validation will be disclosed to the market when completed and integrated into the final drill targeting model as Dateline prepares to test both gold and REE targets in the current campaign.

This press release has been authorized for release by the Board of Dateline Resources Limited.

For more information, please contact:

Stephen Baghdadi

Managing Director

+61 2 9375 2353

Andrew Rowell

Corporate & Investor Relations Manager

+61 400 466 226

[email protected]

www.datelineresources.com.au

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About Dateline Resources Limited

Dateline Resources Limited (ASX:DTR)(OTCQB:DTREF)(FSE:YE1.F) is an Australian company focused on mining and exploration in North America. The Company owns 100% of the Colosseum Gold-REE Project in California.

The Colosseum Gold Mine is located in the Walker Lane Trend in East San Bernardino County, California. On 6 June 2024, the Company announced to the ASX that the Colosseum Gold mine has a JORC-2012 compliant Mineral Resource estimate of 27.1Mt @ 1.26g/t Au for 1.1Moz. Of the total Mineral Resource, 455koz @ 1.47/t Au (41%) are classified as Measured, 281koz @1.21g/t Au (26%) as Indicated and 364koz @ 1.10g/t Au (33%) as Inferred.

On 23 May 2025, Dateline announced that updated economics for the Colosseum Gold Project generated an NPV6.5 of US$550 million and an IRR of 61% using a gold price of US$2,900/oz.

The Colosseum is located less than 10km north of the Mountain Pass Rare Earth mine. Planning has commenced on drill testing the REE potential at Colosseum.

Dateline has also acquired the high-grade Argos Strontium Project, also located in San Bernadino County, California. Argos is reportedly the largest strontium deposit in the U.S. with previous celestite production grading 95%+ SrSO4.

Forward-Looking Statements

This announcement may contain "forward-looking statements" concerning Dateline Resources that are subject to risks and uncertainties. Generally, the words "will", "may", "should", "continue", "believes", "expects", "intends", "anticipates" or similar expressions identify forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from those expressed in the forward-looking statements. Many of these risks and uncertainties relate to factors that are beyond Dateline Resources' ability to control or estimate precisely, such as future market conditions, changes in regulatory environment and the behavior of other market participants. Dateline Resources cannot give any assurance that such forward-looking statements will prove to have been correct. The reader is cautioned not to place undue reliance on these forward-looking statements. Dateline Resources assumes no obligation and does not undertake any obligation to update or revise publicly any of the forward-looking statements set out herein, whether as a result of new information, future events or otherwise, except to the extent legally required.

Competent Person Statement

Sample preparation and any exploration information in this announcement is based upon work reviewed by Mr Greg Hall who is a Chartered Professional of the Australasian Institute of Mining and Metallurgy (CP-IMM). Mr Hall has sufficient experience that is relevant to the style of mineralization and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the "Australasian Code for Reporting Exploration Results, Mineral Resources and Ore Reserves" (JORC Code). Mr Hall is a Non-Executive Director of Dateline Resources Limited and consents to the inclusion in the report of the matters based on this information in the form and context in which it appears.

Company Confirmations

The Company confirms it is not aware of any new information or data that materially affects the information included in the announcements dated 23 October 2024 with regard to the Colosseum MRE and 23 May 2025 with regard to Colosseum Project Economics. Similarly, the Company confirms that all material assumptions and technical parameters underpinning the estimates and the forecast financial information referred to in those previous announcements continue to apply and have not materially changed.

SOURCE: Dateline Resources Limited