麻豆传媒

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Drill cores from 80 bore holes were examined at the mine site and studied with thin sections of the ore-bearing rocks in the laboratory.

The celestite deposits occur at the base of the Windsor group which unconformably overlies the Devonian igneous basement complex. Correlation of the several lithounits of the Windsorian reveals abrupt lateral and vertical changes of lithofacies. All celestite mineralization is confined lithologically within limestone or calcareous beds as a few layers or lenses; most is below calcium sulphate or below equivalent stratigraphic horizons although some occurs in limestone interbeds within calcium sulphate. Generally ore in a rock unit occurs more extensively along the flanks of its paleotopographic ridge. Most abundant is bedded celestite, up to 95 per cent by weight and up to 9 feet in thickness; next in importance are open space fillings. Veins or calcareous patches in calcium sulphate are insignificant. No hydrothermal effect was observed around celestite mineralization.

The history of the celestite mineralization at Enon Lake is deduced as follows: During the sedimentation of Windsorian, the evaporation of water in isolated sea bodies led to gradual increase in the concentration of strontium which finally attained saturation point and started to coprecipitate with calcium carbonate, to form bedded celestite. Strontium precipitation with carbonate or silty carbonate attained a maximum just before the brine became saturated in calcium sulphate. In places allo-chemical limestone was deposited, deformed, and filled by celestite which had been precipitated following the limestone. During diagenesis, some post-depositional features were formed.

Future exploration of celestite should concentrate on carbonate or calcareous beds underlying calcium sulphate, or underlying stratigraphically equivalent beds. Along the flanks of paleotopographic highs is more preferable than highs or valleys.

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Pages:137
Supervisor: G. C. Milligan

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