Early Cambrian alluvial fan-deltas in the Georgina Basin, Australia
Titel:
Early Cambrian alluvial fan-deltas in the Georgina Basin, Australia
Auteur:
Eyre, B.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 41 (1994) nr. 1 pagina's 27-36
Jaar:
1994-02
Inhoud:
Two formations, the Mt Baldwin Formation and Andagera Formation, show a full spectrum from proximal to distal facies associated with shelf type alluvial fan-delta sedimentation. These facies reflect prevailing tectonic and eustatic conditions and the resultant sedimentation patterns during the Early Cambrian. The synsedimentary tectonic and eustatic history is divided into a number of stages: Stage 1, continuous gradual uplift during a lowstand in sea level and the deposition of thickly bedded coarse sandstone and granule to pebble conglomerate with medium-scale planar cross-beds and channel-scoured bases; Stage 2, continuous gradual uplift during a highstand in sea level marked by a minor marine transgression and deposition of laminated yellow and green siltstone and fine sandstone with occasional flaser bedding, water-escape structures and convolute bedding; Stage 3, a fall in sea level and gradual progradation of an alluvial fan into a coastal environment with deposition of wavy laminated siltstone, coarsening and fining-upwards sandstone, and interbedded sandstone and siltstone with herringbone and medium-scale planar cross-beds; and Stage 4, continued gradual uplift of the source area during a lowstand in sea level and deposition of thickly bedded sandstone which coarsens into granule and pebble conglomerate with pebbly cross-beds and scoured bases.
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