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- Title
Sedimentology of 40 000 year Milankovitch-controlled cyclothems from central Hawke's Bay, New Zealand.
- Authors
Haywick, Douglas W.; Carter, Robert M.; Henderson, Robert A.
- Abstract
Cyclothemic sedimentary rocks of the Plio-Pleistocene Petane Group outcrop extensively in the Tangoio block of central Hawke's Bay, New Zealand. They are products of inner to mid-shelf sedimentation and were deposited during glacio-eustatic sea level fluctuations along the western margin of a shallow, pericontinental seaway located in a forearc setting. The succession consists of five laterally continuous cyclothems, each containing a fine grained interval of silt and a coarse grained interval of siliciclastic sand ± gravel or limestone. Five sedimentary facies assemblages comprising 20 separate facies have been recognized. Coarse grained intervals of cyclothems were deposited mostly during relative sea level lowstands and contain up to four facies assemblages: (1) a non-marine assemblage (with three component facies, representing braided river and overbank environments); (2) an estuarine assemblage (with three component facies, representing tidal flat and mud-dominated estuarine environments); (3) a siliciclastic shoreline assemblage (with six component facies, representing greywacke pebble beach, shoreface and inner shelf environments); and (4) a carbonate shelf assemblage (with four component facies, representing tide-dominated; inshore and shallow marine environments). Fine grained intervals of cyclothems were deposited during sea level highstands when the Tangoio area was generally experiencing mid-shelf sedimentation. This produced an offshore assemblage consisting of four component facies. The distribution of facies assemblages during relative sea level lowstands was dependent upon proximity to the shoreline, the type and rate of sediment supply to the basin, and shelf hydrodynamics Carbonate shelf facies dominate coarse grained intervals in Cyclothems 3-5, but siliciclastic shoreline and non-marine facies dominate in Cyclothems 1 and 2. The abrupt change from silieiclastic to carbonate sedimentation during relative sea level lowstand deposition...
- Subjects
NEW Zealand; SEDIMENTARY rocks; PLIOCENE stratigraphic geology; BAYS
- Publication
Sedimentology, 1992, Vol 39, Issue 4, p675
- ISSN
0037-0746
- Publication type
Article
- DOI
10.1111/j.1365-3091.1992.tb02144.x