Holm, R.J., and Bell, D.H. (2013) Sedimentology and structure of the Malvern Hills Coal Mine, Canterbury, New Zealand. New Zealand Journal of Geology and Geophysics, 56 (1). pp. 39-52.

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Abstract

The Malvern Hills Coal Mine provides an opportunity to gain insight into the stratigraphy and sedimentology of the Broken River Formation while addressing the complex deformation of range-front tectonics. An up-to-date geological map, stratigraphic columns and cross-sections have led to a greater understanding of both the mine and regional geology. The stratigraphy reflects a transgressive sequence: the Broken River Formation comprises fining-upwards cycles of flaser- and lenticular-bedded quartz sandstones and carbonaceous mudstones and coal seams representing a coastal swamp environment. Cross-bedded marine quartz sandstones of the overlying Conway Formation are typical of bar or dune settings, and lenses of tidal sedimentation reflect a lower intertidal–subtidal environment. NW–SE compression resulted in D1 tilting and block-faulting along range-front structures. Subsequently, D2 conjugate strike-slip shears bisect the mine forming a deformation wedge. Inside this, D3 folding about NE–SW hinges and D4 listric break-out faulting of the folds has resulted in sheared anticline-syncline pairs.

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