麻豆传媒

The MacEachern - Ponsford Memorial Award - 1992

The three-dimensional geometry of the Mullins Coal (Westphalian C) provides information about its origin and potential for commercial exploitation. Controls for peat accumulation are allogenic in contrast to a previous autogenic model. Sedimentary structures, observable in drill core and coastal outcrop, define four facies assemblages: fluvial channel deposits comprising trough cross-bedded sandstone and conglomerate; bayfill deposits comprising fine cross-laminated sandstone, laminated siltstone, and paleosols; coal deposits comprising bituminous A coal and shaly coal; and well-drained floodplain deposits comprising oxidized fine sandstone and mudstone. The coal ranges from 0.56-2.13 meters thick and extends for 15 km. The seam is thickest overlying fluvial sandstone deposits west of the Bridgeport Anticline near Victoria Mines. Thinning and splitting of the seam, associated with bayfill deposits, increase eastward towards the Glace Bay Syncline. Flooding of a distal braidplain caused brackish water to accumulate in a topographic low forming a protected inland bay. The presence of agglutinated foraminifera in bayfill shales testifies to marine influence. Ponding of freshwater near maximum marine transgression stage resulted in the accumulation of unusually thick paralic peat. The Mullins coal seam is favourable for an open cast pit as it overlies fluvial sandstone and is less than 50 metres below the surface where the coal is thickest.

Keywords: coal geometry, inner bay, braided fluvial, marine transgression
Pages: 103
Supervisor: Martin Gibling