Since acquiring Jervois in 2011, the copper mineral Resources have been significantly been upgraded at Jervois.
Confidence levels in the resource estimates have been strengthened, with 68% of the total copper mineral Resources in the Indicated category. The total copper resource estimates now stand at : -
The considerable advances in the resource base when compared with the previously reported estimate, are due to the confirmatory infill drilling undertaken from June 2019 to March 2020, coupled with improved understanding of the geological controls on mineralisation. This was achieved through the systematic incorporation of drill results in the geological models and adapting the drill plans accordingly.
The progress in upgrading of the mineral Resource at the Jervois Base Metal Project is shown below.
The new Resource Estimates for the Reward, Rockface and Bellbird deposits, together with the Reward South (previously Green Parrot) estimate from 2015 are detailed below in Table 1.
During the last 4 years the KGL geology team has greatly improved the understanding of the controls of mineralisation and disposition of the mineralised lodes. As outlined in the August 2019 JORC report, improved field protocols, supplementing legacy core-logging codes, were introduced in 2017 for lithology, alteration, mineralisation and structures.
The result has greatly enhanced geological understanding and consistency in logging of lithology, alteration, mineralisation and structural domains and subgroups. KGL now recognise two main styles of mineralisation and alteration/metamorphic mineral assemblages:
1. Lower tenor, primary syn-depositional or stratabound disseminated sulphides and
2. Higher grade, structurally controlled shoots representing both remobilised stratabound syngenetic mineralisation, possibly related to late regional intrusion-related mineralising event.
Higher grade mineralised shoots are the result of reworked and remobilised primary strata-bound base metals during deformation. During late stage deformation regional-scale granite intrusions likely provided the heat and fluids that remobilised copper from primary (stratabound) units, into structural traps such as anticlinal fold hinges. The structural framework for this is supported by research of the Northern Territory Geological Survey (e.g. McGloin et al 2019 and Weisheit et al 2019). The shoots are observed as massive or semi-massive sulphidemagnetite veins and chalcopyrite-rich brecciated veins as shown in the image below.
The improved geological model, upon which this resource update is based, widens opportunities to target higher grade extensions and repetitions within favourable host rocks and structures in other areas adjacent to known deposits and in other prospects at Jervois and the surrounding Unca Creek tenement.
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