Geology & Exploration

  • Mexico (163,000 hectares)

    The land package is under-explored and the proximity to the large Camino Rojo mineralized system, hosting 9.5 million ounces gold in measured and indicated gold resources (353 million tonnes at 0.83 g/t)[1], provides a highly prospective opportunity. Exploration on the project is somewhat challenged due to the presence of a thin alluvial soil and caliche cover impacting geochemical surface expressions, but the potential to discover mineralization is considered excellent.

    [1]   The Camino Rojo Mineral Resource estimate has an effective date of June 7, 2019 and was prepared using the CIM Definition. Additional information can be found in the "Camino Rojo Project Feasibility Study NI 43-101 Technical Report” on this website or on SEDAR, dated January 11, 2021.

  • Geology & Mineralization

    Camino Rojo is an intrusive related, polymetallic gold-silver-zinc-lead deposit hosted in clastic sedimentary rocks along the boundary between the Mesa Central physiographic province and the Sierra Madre Oriental fold and thrust belt. The deposit is situated between splays of the regional northwest trending San Tiburcio fault zone, beneath a broad pediment of Tertiary and Quaternary alluvium. This pediment is surrounded by uplands of folded marine limestone of Late Jurassic through Cretaceous ages.

    The most important host to gold mineralization is the Caracol Formation, a rhythmically interbedded sequence of weakly calcareous turbiditic sandstones, siltstones and shales. The underlying Indidura Formation, comprised of regularly bedded siltstones and shales, and the Cuesta del Cura limestone, recrystallized to fine-grained white marble, hosts a minor amount of polymetallic sulfides. Narrow igneous dikes intruded the sediments along linear NE-striking faults.

    Mineralization is associated with a network of sheeted carbonate veins and breccia controlled by both primary bedding and discordant structures. Vein networks are enveloped by a zone of potassic alteration with low-grade disseminated gold in pyrite. The dikes are variably mineralized and display sericitic alteration.

    Near-surface oxidation extends to depths more than 100m and extends to greater depths along structurally controlled zones of fracturing with high permeability. Oxidation of the deposit to depths of 100 to 150 m is approximately 100%. The underlying transitional zone of mixed oxide/sulphide extends to depths of 200 to >250m and is characterized by partial oxidation controlled along bedding and structures. Oxidation in the transitional zone is enhanced along structural zones and envelopes all strata, dependent on fracture intensity, with an oxide halo of several metres. Adjacent sandy layers are permeable and preferentially oxidized outward many tens of metres, creating a stratigraphically interlayered sequence of oxide and sulphide material at the cm scale. Such robust near-surface oxidation of the Camino Rojo type deposit will support a bulk-mineable open-pit scenario.

  • 2021 Exploration

    Orla’s exploration work in 2021, during a construction year, will be modest and focused on supporting study work for existing deposits and new target identification. It can be classified in two categories:

    1. Near-Deposit: Exploration to support study and expansion of existing deposits.
    2. Regional Exploration: Activities to generate new discoveries.

    Near-Deposit Expansion

    Program: Camino Rojo Sulphides

    Completion of a directional drilling program that commenced in the fourth quarter of 2020. The program consists of close-spaced, 25-metre drilling of the sulphide zone, over the down plunge extension of the Camino Rojo deposit.

    Objective: The new information collected will support development scenario planning for the large sulphide resource which hosts 7.3 million ounces of gold in measured and indicated resource categories (259 million tonnes at 0.88 g/t)[1]. The drilling will provide additional information about the continuity and geometry of the higher-grade mineralization and provide new material for geotechnical and metallurgical studies.

    Program: Camino Rojo Oxides

    Completion of a 2,500-metre core drilling program on Fresnillo’s property and integration of Orla’s geological and resource models with Fresnillo’s drill data.[2]

    Objective: Enable material on the Fresnillo concession to be included in the measured and indicated mineral resource categories and to be considered in an updated mineral reserve estimate.

    Regional Exploration

    Program: Completion of a 7,500-metre rotary (“RAB”) Covered Bedrock Interface (“CBI”) survey.

    Objective: The 2021 regional program will seek to define drill targets for the discovery of satellite deposits near the Camino Rojo deposit. A large part of the property has a thin cover of alluvial soil and calcrete or caliche layers (calcium carbonate concretions). The resulting geochemical samples from the survey in combination with geophysical IP surveys planned in 2021 and existing geological information will allow for the definition of new priority drill targets.

    [1]   The Camino Rojo Mineral Resource estimate has an effective date of June 7, 2019 and was prepared using the CIM Definition. Additional information can be found in the Camino Rojo Technical Report dated June 25, 2019.

    [2] As announced on December 21, 2020, Orla completed a Layback Agreement with Fresnillo PLC (“Fresnillo”) that will allow Orla to expand the Camino Rojo oxide pit onto part of Fresnillo’s mineral concession located immediately north of Orla’s property. 

  • Maps and Sections

  • Stratigraphic Column References:
    • Barboza-Gudiño, J., Zavala-Monsiváis A., Venegas-Rodríguez, G., Barajas-Nigoche, D., 2010
    • Enriquez, E., 2010
    • Ortega-Flores, B., Solari, L.A., Escalona-Alcazar, F., 2015
    • Nieto-Samaniego, A.F., Alaniz-Álvarez, S.A., and Camprubí, A., 2007
    • Sanchez, S., 2017

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