Holocene sediment lithofacies and dispersal systems on a storm-dominated, back-arc shelf margin: The east Coromandel coast, New Zealand Journal Paper
- Author
- Barry E. Bradshaw, Terry R. Healy, Campbell S. Nelson, Paul M. Dell, Willem P. de Lange
- Year
- 1994
- Journal / Source
- Marine Geology
- Volume
- 119
- Number
- 1-2
- Pages
- 75-98
- Keywords
- Coromandel, Holocene, sea level, lithofacies, siliciclastic sediments
- Summary
- Holocene sediment lithofacies and dispersal systems on the east Coromandel shelf, New Zealand, are mainly characterised by an accommodation-dominated regime in which autochthonous siliciclastic sediments were reworked through erosional shoreface retreat during the post-glacial marine transgression (12.0–6.5 ka). Stabilisation of sea level at its present position ca. 6.5 ka initiated onshore reworking of the autochthonous deposits into fine-grained regressive barrier and shoreface sands, while coarser sands remained offshore to form an erosional-lag inner-shelf deposit. Modern episodes of shoreface erosion rework fine and coarse autochthonous sands offshore and northwards into very large (η = 0.5–2.5 m; λ = 250–1500 m) submarine dunes. The submarine dunes are similar in form to sand ridges on the North American Atlantic shelf, but with crests striking perpendicular to both the shoreline and generating flows. Allochthonous siliciclastic lithofacies are also important aspects of east Coromandel shelf sedimentation, and are transported offshore from infilled estuary systems to form very fine-grained upper shoreface and muddy mid-shelf sands.