Summary:
The Tritton Copper Operations area is host to a cluster of copper deposits hosted within Ordovician aged turbidite sequences from the Girilambone Basin. The Girilambone Basin forms part of the Lachlan Fold Belt. The deposits are characterised by massive to semi-massive pyrite and chalcopyrite sulphide occurrences. Deposit geometries are typically tabular. Dimensions vary depending on the size of the system and range between a strike of 15m to 250m; down-dip length from 90m to more than 2,000m; and from 2m to 80m in width. Mineralised assemblages are dominated by pyrite with lesser chalcopyrite, and minor gold and silver concentrations. Primary copper mineralisation occurs as banded and stringer chalcopyrite within pyrite-rich units.
The Tritton underground mine has been the primary source of ore feed for the processing plant (Tritton Mill) and from 2016, the Murrawombie underground mine has been the supplemental ore source.
New mine projects:
• Budgerygar deposit – an extension of the Tritton underground mine;
• Avoca Tank underground mine; and
• Maiden mineral resource estimate at the Constellation deposit.
Tritton Deposit
The Tritton deposit is a sulphide copper mineralised body located on ML1544 in central New South Wales (NSW), Australia. The deposit geology is best described as a structurally controlled sulphide deposit. Copper mineralisation, in the form of chalcopyrite is associated with a late-stage regional deformational event.
Sulphide mineralisation within the Tritton tenement package has been classified as either a structurally controlled epigenetic sulphide system or a stratiform “Besshi style” volcanogenic massive sulphide (VMS) deposit. Recent geological investigations at both the Tritton and Murrawombie deposits have identified a sulphide mineralisation occurring late in the structural deformation events. There is decreasing support for the VMS model of deposit formation as we can better undertsnading of the deposits.
Sulphide mineralisation is dominated by massive, banded and stringer pyrite +/- chalcopyrite, with a relatively consistent massive pyrite – chalcopyrite unit along the hanging wall contact. Alteration assemblages adjacent to mineralisation are characterized by an ankerite/chlorite footwall and silica sericite hanging wall.
The main Tritton mineralised zone is tabular in nature with an overall down dip length of 1.9 kilometres with mineralisation still open at depth. Mineralisation begins at approximately 155m below surface (5,115mRL). The main body varies in thickness averaging 6-8m above the main “roll over” at 4,500mRL. Below the “roll over” the mineralised sulphide package thickens with true widths in the order of 15 to 30m to 4,300mRL. Below this the mineralised body dips at a shallower angle (25) and thickens to 70m thick down to the 3,970mRL. The mineralised system below 4,300mRL level is influenced by a NW-SE trending F4 fold corridor. Within the fold corridor the mineralised system becomes progressively deformed and is responsible for the geometry change (N-S trend to E-W trend) and increased thickness.
Murrawombie Deposit
The Murrawombie deposit is a sulphide copper deposit located on ML1280 in central New South Wales (NSW), Australia. The deposit geology is best described as a structurally controlled sulphide deposit. Copper mineralisation, in the form of chalcopyrite is associated with a late-stage regional deformational event.
Copper mineralisation at the Murrawombie deposit is hosted within early to mid-Ordovician turbidite sediments, forming part of the Girilambone Group. Turbidite lithologies range from shale, siltstone, fine grained sandstone and occasional medium-coarse grained sandstones. Occasional mafic sills intrude the sediment package. Several regional deformation events are evident at the Murrawombie deposit. Sulphides (pyrite and chalcopyrite) occur along sites of dilation associated with a later ductile deformational event. Post mineralisation faulting is common in the form of north-south striking (mine grid) graphitic faults.
The Murrawombie deposit consists of several elongate sulphide envelopes orientated parallel to a pervasive S2 fabric which is interpreted as forming parallel to bedding. The elongate sulphide lodes are defined by a long down dip axis (+300m) and a shorter strike (100m to 150m) and thickness (30m). To date eleven sulphide lodes have been discovered at Murrawombie with the 102, 105 and 108 lodes the largest discovered to date. Sulphide mineralisation is dominated by pyrite and chalcopyrite, which varies from massive pyrite +/- chalcopyrite to erratic stringer pyrite/chalcopyrite veins. Sulphide mineralisation pinch and swells which is in part a result of bounding graphitic fault zones deforming the mineralised lenses. Post mineralisation faulting, in particular graphitic faults trend at an oblique angle (approximately 10°) to mineralisation. The graphitic faults constrain the northern strike extensions of the Murrawombie mineralised system.
The Murrawombie resource occurs as several discrete/stacked tabular lenses covering an area approximately 750m north–south and 900m east–west with mineralisation starting from near surface. Fresh mineralisation begins at approximately 140m below surface.
The Murrawombie mineralised system is tabular in nature with an overall down dip length of 750m with mineralisation still open at depth. Mineralisation begins at approximately 70m below surface (5,200mRL). The mineralised lodes vary in thickness averaging 6-10m and dip between 35° - 45° east. Strike extents vary from 50m to 150m.
Budgerygar Deposit
The Budgerygar mineralised system is tabular in nature with an overall down dip length of 750m with mineralisation still open at depth. Mineralisation begins at approximately 70m below surface (5,200mRL). The mineralised lodes vary in thickness averaging 6-10m and dip between 35° - 45° east. Strike extents vary from 50m to 150m.
Avoca Tank
The main Avoca Tank Deposit is based on several discrete tabular lenses over an area approximately 130 m north west – south east, 100 m north east – south west and with mineralisation starting from 50m below the surface with fresh mineralisation approximately staring from 75m below surface. The individual tabular lenses have strike lengths ranging from 15 to 60m and a down dip extent ranging from 130 to 360m. The lenses vary in true width from 2 to 30m. Narrow across strike mineralisation also occurs in the footwall of the Main Avoca Tank resource and trend approximately perpendicular to the main Avoca Tank mineralisation with an approximate strike length ranging from 40 to 140m.
Constellation Deposit
The Constellation mineralised system is tabular in nature with an overall down dip length of 1,100m with mineralisation still open at depth. Mineralisation begins from 4m below surface (~160mRL). The mineralised lodes vary in thickness averaging from 1-25m. The main sulphide body dips between 30° - 35° SE with a strike extent typically between 200m to 300m. The sub-vertical sulphide body along the northern margin of the deposit trends east-west with a thickness typically =10m.