SOUTH PARA RESERVOIR

WILLIAMSTOWN - SOUTH AUSTRALIA

IRON MINE

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GEOLOGY

SOUTH AUSTRALIA

that the Barossa Complex rocks had r¡ndcrEef¡ç at least three periods of metamorphism, and that two or rnre phaSes of folding had affected the overlying Upper Precambrian rocks. Offler (1966) amplified these studies, and he recogmized three phases of deformation, each accompanied by ttre formatic¡n of foliation, in t|a Upprr Precarnbrian rocks. (EDIT LATER).

llilliamstown is centrally located within the belt of folded and metamorphosed Precambrian to Lower Palaeozoic rocks which form the Mount Lofty Ranges, a structural high bounded to the east and west by Cainozoic sedÍments. The Mount Lofty Ranges rocks were deposited in part of a great synclinal trough (the Adelaide Geosyncline) extending from and beyond Karigaroo Island in the south through the Fl-inders Ranges to the north, thence northwest to ttre Peake and Denison Ranges and nortT¡-east to Broken HilI (Fig. 8). fhese sediments accumulated to more than 25,000 metres in thickness, Yet the general conditions of sedimentation were those of relatively shallow water' hence the basement must have been gradually subsiding during sedimentation over a period of more ttran 800 million years from the Late Proterozoic to the Cambrian (Ludbrook and ,fohns, L97O). ftre sediments are believed to have been derived from the shield area to the htest knot"n as the Gawler Bl-ock, an extension of the crystalline basement of the Western Australian Shield (Parkin , 1969') . During the Cambrian a deep trough with stèep margins developed along a number of fault lines in the southeastern part of the Adelaide Geosyncline, stretching from Kangaroo Island to Kapunda. In this Kanmantoo Trough were deposited rapidly some 18,000 metres of fine-grained deep-water sediments. Íhese mark the end of deposition in the Adelaide Geosyncline before it was affected by crustal movements in the early ordovician, when major folding and mountain-building movements formed the Mount Lofty and Flinders Ranges. During this orogeny granites dated at 49O míIlion years were intruded (White et al, 1967), and metamorphism produced rocks of biotite grade over wide areas (Offler anil l'leming, 1968) . A long period of erosion followed, which included a major continental ice age in the Permia¡r (Parkin , 1969). The crustal troughs to the east and west of the Ranges began to develop in the Permian, and were mobile Èhrough the l{esozoic and Tertiary to the present (Parkin, 1969). Within these troughs mainly marine sediments were deposited (ris. 9) . EDIT LATER.

EMEROO SUBGROUP

The

Aldgate Sandstone

Sandstone, medium to coarse grained, grey, brown, green, quartzitic to micaceous to clayey, flaggy, heavy mineral layers, cross bedding, lenticular bedding; phyllite.

NEOPROTEROZOIC

Min & Max: Torrensian

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haematite (IRON ore)

The

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STONYFELL QUARTZITE

The

Quartzite, feldspathic, with shale interbeds; silty sandstone in part schistose and calcareous.

Stonyfell Quartzite NEOPROTEROZOIC Torrensian

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QUARTZITE BOULDER FIELDS

The

QUARTZ VEINS

Narrow veins of milky or translucent quartz occur in all formations in the area, though they are most abundant in the schistose rocks and in the vicinity of faults. they ãre mostly short, although some up to 20 metres long occur within the Mt. Crawford Granite Gneiss, and one vein almost 150 metres long occurs in the Barossa Complex near the spillway. Minerals other tåan quartz are rare, although coarsely crystalline irregular aggregates of titaniferous hematite are scattered through veíns in most formations. Some veíns in the Barossa Complex and east of the Kitchener Fault carry tourmaline, Iarge isolated feldspar crystals arrd occasionally a few large muscovite flakes, though these are probably quartz-rich pegrmatites rather than true quartz veins. Ttre latter have.probably been derived from the conÈaining rock by lateral secretion into tension fractures and in the vicinity of these fissure fillings there is some alteration of micaceous minerals to sericite. ftre gold-bearing quartz veins, f.or example in the Deloraine fÍeld, commonly contain abundant pyriter and high gold assays are generally reflected by the presence of copper sulphides, the richer veins assaying up to 9t Cu. Here the quartz is cavernous, with honeycomb structure containing abundant quartz crystals (EDIT LATER)

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HEMATITE VEINS

The

WEATHERING & EROSION

The

MOUNT BESSEMER IRON MINE

The Mine was operating from 1871 to 195- and is classed as a Low significance Quarry, Iron Ore, Micaceous Hematite in the Aldgate Sandstone

From Newspaper Articles:

"In the meantime, the syndicate are satisfied with the metallic iron contents of the ore, and are arranging for the erection of a temporary smelter on the ground for the production of pig iron. Mr. J Wesley has submitted plans, and charcoal will be the fuel, of which there is abundant on the range surrounding the mine: This mine was first worked in 1871, when Mr. James Martin, of the Phoenix Foundry, smelted the first ore in the colony there, and part of the product now adorns the front of the Institute as an ornamental railing." - Gawler Bunyip, 23rd of May 1919

 

"There is a big possibility of the Mount Bessemer iron mine; which is situated near to Williamstown. Being opened up in the near future and made one of the big industries of the State." - Gawler Bunyip, 23rd of May 1919.  

1984 to1988 Licence & Exploration:

 

The area around the abandoned Mount Bessemer iron mine was licenced again from 1984 to 1988 for exploration for deposits relating to surface processes and unconformities of iron ore in micaceous haematite.

The Aldgate Sandstone host rock has abundant heavy-mineral banding within its lower section and grades locally into micaceous haematite, the sandstone unit is around 17 meters wide and has been traced for over 3 kilometres. The unit is an extension of the lode the abandoned Mount Bessemer iron Mine worked during its time in operation. 

Ground surveys were done to determine iron content, this concluded with gradient anomalies that corresponded with outcropping beds, and with higher than average iron content in areas that lack outcropping altogether. Percussion drilling of 13 different holes, totalling about 196 meters, the chip samples recovered showed that the mineralisation continues undercover with grading of 30-40% Fe203.

 

The southern area contains sandstones with higher grades, bands extending to widths of 2-2.5 meters containing micaceous haematite. Inferred surveys approximate 200,000 tonnes of suitable material which could be have been used for low-cost micaceous iron oxide anti-corrosion for industrial steelwork.

...

When the South Para Reservoir filled the former Mount Bessemer Iron mine was submerged below the now deep waters of the reservoir. Seeing how far it extends both above ground and in the tunnels below is almost impossible today.  

REFEreNCES

Uhlman, M.W, Ware, M.D, Scott, W.D., Shannon, C.H.C, & Archer, D.S. (1987). Para Wirra. Quarterly reports to licence expiry for the period 5/11/1984 to 1/3/1988. Record 1 of 3. SARIG. 

South Australian Government. (n.d.). SARIG geological map. SARIG. 

Gawler Bunyip, SA: 1863 - 1954. (1911, May 23rd). Mount Bessemer Iron Mine. Trove. 

GHOST RANCH
NEW MEXICO, U.S.A
DEAD MAN'S PASS
SOUTH AUSTRALIA
BORAH FAULT SCRAP
IDAHO, U.S.A