The company’s exploration licence’s at Roberts Hill & Mt Berghaus cover an area of 170 sq km and 179 sq km respectively and are situated approximately 50 kilometres to the south of Port Hedland. The ground is comprised of structurally and chemically altered granitic, intermediate and ultramafic intrusive rocks which are considered highly prospective for additional gold occurrences to the recent discoveries in the region (De Grey’s Hemi)
Both Roberts Hill and Mt Berghaus are located within the Central Terrane region of the Archaean Pilbara Craton, which is comprised of granite, greenstones and sediments which formed between ca. 3600Ma and 2800Ma. The Pilbara Craton appears to be unconformably overlain (at least along its southern margin) by the late Archaean-Palaeo-proterozoic volcano-sedimentary Hamersley Basin sequence. The Pilbara Craton has been subdivided into three structural terranes; the Eastern Terrane consists of large circular, domal granitoid complexes which have intruded belts of tightly folded volcaniclastic rock. In contrast, the Western Terrane is dominated by linear, northeast trending outcrop patterns which are truncated on their south-west margin by the northeast trending Sholl Shear Zone. The Central Granite-Greenstone Terrane separates the Eastern and Western Terranes and contains sediments of the De Grey Group (3015-2950Ma) and the Whim Creek Group. Within the Central Terrane lies the Mallina Basin, a tectonic, rift-like basin that is comprised of sediments of the De Grey Group. Several large granitic plutons are intruded into the Mallina Basin sequence, in addition to highly interesting extremely elevated Mg-rich diorites which appear to have a spatial association with gold and base metal mineralisation within the Mallina Basin.
Both tenements area are dominated by sediments of the De Grey Group, comprising medium to coarse greywacke and shale of the Mallina Formation overlying conglomerate, arkose and shale of the Constantine Formation. A sequence of mafics (Millindinna Intrusion) can be observed throughout much of the southern and eastern Mallina Basin and appears to be restricted to the lower part of the Mallina Formation.
The Mallina Formation has been intruded by several granitoids, dominated by the Portree Granite Complex with a distinctive ovoid magnetic signature. The Portree Granite Complex is an alkaline type granite with thermal aureoles rarely observed in outcrop. The Peawah Granodiorite is also thought to occur on both the Roberts Hill and Mt Berghaus tenements. The Peawah Granodiorite which is a hornblende-rich, alkaline type granite, ranges in composition from granite to tonalite.
Mining and Previous Exploration.
There has been no recorded mining and very limited exploration over the Roberts Hill and Mt Berghaus tenements. This has probably been due to the thick (up to 40 metres) unconsolidated sands covering much of the tenement area and sparse highly weathered outcrop. However, within 10 kilometres of the tenement boundaries are several small mining centres. Mallina and Toweranna were historical gold mining centres whilst Mallina and Peawah historically produced small amounts of antimony. Mallina was discovered in 1888 and mined up until 1918 with reported accompanying small gold production of 3.99 kg. Toweranna historically reported production of 161.7 kg Au. Stibnite and other base metals can occur with the gold.
In terms of nearby exploration, gold and base metals appear to be the prime focus since the early 1970’s, however, some limited platinum group metal (PGM) exploration was also conducted. Nearby historical exploration appears to have focused on the more outcropping central parts of the Mallina Shear Zone. Between 1968 and 1972, Mallina Mining carried out the first modern exploration over the Au-Sb rich Mallina Shear Zone by conducting a detailed soil geochemical sampling program and diamond drilling. Results of both activities were inconclusive.
Between 1973 and 1974, Utah Development Co explored for nickel mineralisation, focusing on the mafic and ultramafic intrusives that have intruded the Mallina Basin sediments. Work appeared to demonstrate geochemical interest, however, activities were abandoned. Between 1981 and 1984, Aquitaine explored for alluvial Au-Sn mineralisation adjacent to the Yule River and across a portion of the Mallina Shear Zone. Several samples contained detectable Sn (maximum 600 ppm), Ta (maximum 230 ppm) and Au (0.83 ppm).
In 1992-1993, Aztec attempted to test the alluvial gold potential of part of the Mallina Basin area with RAB drilling. A total of 17 holes was drilled to a maximum depth of 28m, which included up to 20m of alluvial cover over Archaean bedrock. Examination of the samples revealed inconclusive and sporadic gold, with limonite-goethite grains the dominant heavy mineral with accessories magnetite, chromite, chalcopyrite and cassiterite.
In 1981 to 1983, WMC explored for gold mineralisation across the Mallina Shear Zone using lag geochemistry (-4mm+2mm), which highlighted two gold-arsenic trends with values up to 150 ppb Au and 2000 ppm As. The original lag anomalies were later downgraded by follow up surface geochemistry and no drilling was undertaken.
Between 1992 and 1993, MIM explored parts of the Mallina Basin for Whim Creek style Cu-Zn mineralisation. A prospective exhalite horizon was targeted with maximum rock geochemistry of 110 ppm Cu, 225 ppm Zn and 670 ppm As, however, further exploration ceased.
Hunter Resources Ltd explored for Au and PGM’s between 1986 and 1989 over exposed mafic-ultramafic lenses at the base of the Mallina Formation. RC drilling of selected lenses returned disappointing results.
The driving force and catalyst behind the identification of economic gold mineralisation in the Mallina Basin has been the exploration and development work of De Grey Mining Ltd over the past 5 to 6 years. In 2019, a new style of intrusion-related gold mineralisation (? high Mg-rich diorite) was identified at the Toweranna deposit. With accelerated drilling campaigns at the Toweranna resource, this has now increased to 524koz @ 2.2g/t to become the second largest and second highest grade deposit discovered by De Grey. Using good geological and geophysical extrapolation, De Grey have now identified seven new intrusive-related gold targets analogous to Toweranna. In 2020, the Hemi gold occurrence was the first of these new De Grey targets to be tested, which has since confirmed gold mineralisation across three defined Hemi zones, Aquila, Brolga and Crow. Another of these newly defined targets, still to be tested, is De Grey’s Shaggy gold occurrence, which is less than 200 metres from the Caeneus Roberts Hill tenement boundary.
Exploration programs testing the other six identified intrusion-related targets along the Berghaus and Antwerp Structural Trends are about to commence later in 2020.
With the Mallina, Berghaus and possibly new (previously unidentified) shear trends crossing the Roberts Hill and Mt Berghaus tenements, Caeneus is highly encouraged that similar intrusive related gold anomalism will be discovered within its tenements.
The Company’s Yule River exploration licence consists of two separate blocks totalling 125 square kilometres. The project is situated 40km southwest of Port Hedland with several all-weather tracks traversing the licence.
The tenement comprises sediments and volcanics of the Louden Volcanic Member as well as the Constantine Sandstone. However, lithologies associated with the Boondarie Greenstone sequence and mylotonic rocks associated with the Sholl Shear Zone have been the focus of soil sampling to date. The area is considered prospective for gold, platinum group metals and base metals.
Mining and Previous Exploration
There has been no recorded historical mining activity on the Yule River tenement. During the early 1970’s, the Australian Inland Exploration Company explored for base metals along proximate to the Sholl Shear Zone that forms the focus of the Company’s Yule River Project. No significant exploration discoveries were made, however, drilling (nearby to the current Golden State Mining Balla Yule occurrence) in 1973/74 by Australian Inland Exploration intersected an Archaean gabbro having a best assay of 52.3% total Iron, 4.55% Titania and 5.3% Chrome oxide.
In the early 1980’s, Esso Exploration carried out volcanogenic massive sulphide exploration activities along the Sholl Shear Zone. Although analogous lithologies to the Mons Cupri occurrence were identified, results were generally disappointing and further exploration was abandoned.
Approximately one decade later, Western Mining Corporation conducted BIF hosted gold exploration along the Sholl Shear Zone. Over 1000 metres of reverse circulation drilling was carried out intersecting Quaternary and Tertiary cover up to 80m thick comprising indurated sands and thick unconsolidated pebble and cobble alluvial material. A variety of lithologies including serpentinised ultramafics, chloritic schists, granitoids, mafic and felsic volcanics, fuchsitic cherts and a quartz-feldspar pyrite zone with traces of chalcopyrite were identified from the drilling. The best intersection was 2m @ 0.45 ppm Au from 55-57m in a serpentinized ultramafic. Intense quartz-magnetite-pyrite-chalcopyrite alteration was noted in one hole with maximum geochemistry of 0.008 ppm Au, 495 ppm Cu and 7 ppm Sb. Results were inconclusive and WMC relinquished title to the Sholl Shear Zone areas and abandoned further exploration.
In 1993, CRA Exploration carried out drilling for base metals, nickel and gold. Drilling was hampered by high water flows with best intersections of 450 ppm Cu and 1500 ppm Zn.
More recent activities such as VTEM and Aeromagnetics (Brumby Resources, 2006) have been conducted with interesting but inconclusive results. Currently, most of the Sholl Shear Zone region is covered by either Caeneus or Golden State Mining with the latter company actively carrying out further gold and base metals exploration..