High-Grade Sediment Hosted Mineralization Extended at Pampa Medina – 300m Western Step-out SMRD-16 Intersects 10m of 4.2% Cu within 70m of 1.0% Cu

About this update from Marimaca Copper Corp.

VANCOUVER, British Columbia, Aug. 15, 2025 (GLOBE NEWSWIRE) -- Marimaca Copper Corp. (“Marimaca Copper” or the “Company”)  (TSX:MARI, ASX:MC2) is pleased to announce further drilling at the Pampa Medina deposit, extending the high-grade sediment-hosted manto-system 300m to the west from previous drilling. Pampa Medina is located at low altitude approximately 28km east of the Company’s Marimaca Oxide Deposit (“MOD”) in a flat “pampa” valley within the Atacama Desert (Figure 1). The Company is executing a 10,000m extensional drilling program with three rigs currently on site. Highlights Sergio Rivera, VP Exploration of Marimaca Copper, commented: “SMRD-16 is a further 300m step out to the west of the previously announced SMRD-12 and has intersected a similar broad zone of high-grade copper mineralization, including 70m at 1.0% and a number of discrete very high-grade zones. “The area of interest currently confirmed by drill intersections extends over 1.2km east-west by 1.2km north-south, with an average true thickness of between 50m to 100m. We currently have no observable reasons to indicate that mineralization would not be continuous while the sedimentary unit exists and, as a result, we see enormous potential to both the north and west of the current drilling. “To the east, the block was uplifted significantly, which caused a thinning of the mineralization. Despite this, we intersected a broad zone of oxide copper mineralization at above economic cut-off grades for Pampa Medina and we, therefore, continue to see strong potential for oxide resource growth in all directions. “Our strategy remains to step out significantly to try to define the limits of what is a very large system, but we will now also turn our attention to planning an infill campaign in the broader Pampa Medina project area with the objective of delineating updated resources for the project.” Hayden Locke, President and CEO of Marimaca Copper, commented: “The depth of these new intersections continue to indicate that it will be an underground opportunity, once the Pampa Medina oxide open pit has been considered. Our early analysis indicates an economic cut-off grade requirement of between 0.5% and 0.8%, depending on copper price. With that in mind, we are targeting mineralized intersections with true widths exceeding 20m at an average copper grade of 1.0% or more. The last four drill holes have delivered widths and grades that materially surpass this requirement and, as a result, we see enormous potential for a large scale, highly economic, underground copper mining opportunity. “Sergio Rivera and our exploration team continue to deliver outstanding value with the extension of the thick, high grade manto mineralization to the west. The continued exploration success at Pampa Medina reinforces our goal at Marimaca: to become a significant copper producer with the unique, low-cost, advanced-stage asset in the MOD, and transformational district scale upside anchored by Pampa Medina and Madrugador. “With the upcoming release of the MOD DFS, our strategy remains multi-pronged: 1) deliver a near-term, low-cost 50ktpa copper cathode mine in a Tier-1 jurisdiction; 2) advance the Pampa Medina and Madrugador Oxide projects to grow our cathode production and extend mine life; and 3) continue to define the district-scale exploration potential of our large land package.” Overview of Pampa Medina Pampa Medina is a stratiform or manto-style copper deposit dominantly hosted in Jurassic-Triassic sedimentary units (sandstones, conglomerates, tuffs and black shales) overlain by andesitic volcanics and underlain by an Upper Paleozoic complex of metamorphosed sediments, volcanics and intrusions. It´s intruded by a dyke swarm and affected by post mineral normal faulting (Figure 4). Copper was originally identified in near-surface oxide mineralization dominated by atacamite, chrysocolla and both secondary and primary chalcocite, and has now been identified in high-grade zones of chalcopyrite and bornite which extend laterally down-dip beyond the oxide-primary transition. Following Marimaca’s consolidation of the project area and surrounding land packages in 2024, the Company reinterpreted all available geological information (for the first time as one) and developed an updated geological model for Pampa Medina, which identified the lower sedimentary units of interbedded sandstones, shales and conglomerates as the productive horizons for future drill targeting. Oxide copper mineralization was logged in historical drilling in near-surface, uplifted blocks, with the model of continuity in the intact lithological sequence in deeper blocks for primary mineralization to be tested by Marimaca’s 2025 drilling campaign. SMRD-16 materially extends the high-grade manto to the west, increasing the defined mineralized stratigraphy across a 1.2km by 1.2km area (Figures 2 and 4). Weakly mineralized sandstones were intercepted from 116m, with the main high-grade mixed-sulphide, sediment hosted mineralization starting at 438m downhole. Hole SMRD-15 was planned to confirm the uplifted basement in the eastern direction of the Pampa Medina main target. Oxide mineralization was intercepted at 122m, extending to 204m depth (Figure 3). Exploration focus will remain on the western and northern regions of the Pampa Medina main target, which both remain open. Figure 1: Regional Map – Marimaca, Pampa Medina and Regional Infrastructure Figure 2 – Pampa Medina Deposit and Step-out Drilling Locations Figure 3 – Pampa Medina Lithology – SMRD-16 Downhole Sequence Figure 4 – Cross Section Looking North – Pampa Medina SMRD-15 to SMRD-16 Table 1: Table of Intersections Table 2: Drill Collars Sampling and Assay Protocols True widths are estimated as 95% of reported intervals, based on down-hole bedding and structural measurements. DDH holes were sampled on a 2m continuous basis, halved by a conventional core splitter on site with one half sent to the Andes Analytical Assay preparation laboratory in Copiapó and the pulps then sent to the same company laboratory in Santiago for assaying. Samples were prepared using the following standard protocol: drying; crushing all sample to -1/4” and passing through a secondary crusher to better than 80% passing -10#; homogenizing; splitting; pulverizing a 400-600g subsample to 95% passing -150#; and a 125g split of this sent for assaying. All samples were assayed for %CuT (total copper); %CuS (acid soluble copper). A full QA/QC program, involving insertion of appropriate blanks, standards and duplicates was employed with acceptable results. Pulps and sample rejects are stored by Marimaca Copper for future reference. Qualified Person / Competent Person The technical information in this news release, including the information that relates to geology, drilling and mineralization was prepared under the supervision of, or has been reviewed by Sergio Rivera, Vice President of Exploration, Marimaca Copper Corp, a geologist with more than 40 years of experience and a member of the Colegio de Geólogos de Chile and of the Institute of Mining Engineers of Chile, and who is the Qualified Person for the purposes of NI 43-101 responsible for the design and execution of the drilling program. The information in this announcement which relates to exploration results for the Pampa Medina Project is based on, and fairly reflects, information and supporting documentation prepared by Sergio Rivera, VP Exploration of Marimaca, a Competent Person who is a member of the Comision Minera (Chilean Mining Commission), Colegio de Geólogos de Chile and of the Institute of Mining Engineers of Chile. Mr. Rivera has sufficient experience that is relevant to the style of mineralisation and types of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the Joint Ore Reserves Committee Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves. Mr. Rivera consents to the inclusion in this announcement of the matters based on his information in the form and context in which it appears. Contact Information For further information please visit www.marimaca.com or contact: Tavistock +44 (0) 207 920 3150 Emily Moss / Ruairi Millar [email protected] Forward Looking Statements This news release includes certain “forward-looking statements” under (without limitation) applicable Canadian securities legislation, including, without limitation, statements regarding the development of activities at Pampa Medina, the potential growth of Pampa Medina, and the discovery’s potential to complement the MOD. There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially from those anticipated in such statements. Forward-looking statements reflect the beliefs, opinions and projections on the date the statements are made and are based upon a number of assumptions and estimates that, while considered reasonable by Marimaca Copper, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be materially different from the results, performance or achievements that are or may be expressed or implied by such forward-looking statements and the parties have made assumptions and estimates based on or related to many of these factors. Such factors include, without limitation: risks that the development activities at Pampa Medina will not progress as anticipated, or at all, risks related to share price and market conditions, the inherent risks involved in the mining, exploration and development of mineral properties, the uncertainties involved in interpreting drilling results and other geological data, fluctuating metal prices, the possibility of project delays or cost overruns or unanticipated excessive operating costs and expenses, uncertainties related to the necessity of financing, uncertainties relating to regulatory procedure and timing for permitting submissions and reviews, the availability of and costs of financing needed in the future as well as those factors disclosed in the annual information form of the Company dated March 27, 2025 and other filings made by the Company with the Canadian securities regulatory authorities (which may be viewed at www.sedar.com). Readers should not place undue reliance on forward-looking statements. Marimaca Copper undertakes no obligation to update publicly or otherwise revise any forward-looking statements contained herein whether as a result of new information or future events or otherwise, except as may be required by law. None of the TSX, ASX or the Canadian Investment Regulatory Organization accepts responsibility for the adequacy or accuracy of this release. This announcement was authorised for release to the ASX by the Board of Directors of the Company. Appendix 1 – JORC Code 2012 Table 1 (ASX Listing Rule 5.7.1) Section 1 Sampling Techniques and Data Section 2: Reporting of Exploration Results Infographics accompanying this announcement are available at https://www.globenewswire.com/NewsRoom/AttachmentNg/332a7840-2cc2-4c78-a638-9e282786f709 https://www.globenewswire.com/NewsRoom/AttachmentNg/50c9eedd-7576-49cf-a5c7-653dfe22185a https://www.globenewswire.com/NewsRoom/AttachmentNg/2883183a-f75a-4564-8162-28d4bc4f63ce https://www.globenewswire.com/NewsRoom/AttachmentNg/359456f3-6464-4e2c-b7f5-72f3b5b7c0da

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