Beach and Continental Shelf Recent Sedimentation of the Kakanui District, North Otago.

Anderson, SG

Beach and offshore sediments were systematically sampled and studied during this work.
Textural studies resulted in both on and offshore sediments being modelled by mixing of two modes, a fine modern modal population and a coarse relict modal population. The modern mode is analogous for beach and offshore sediments, the relict mode is finer in the beaches than offshore. This fining is due to abrasion and drowning of coarser clasts by the transgressing sea.
With the use of a microprobe, detrital grains were analysed and compared to analyses of minerals from inferred source areas.
Appraisal of all textural, mineralogical and chemical data results in definition of the nature of the sources of the Kakanui sediments.
Green hornblende and hypersthene are inferred to be derived from the rocks of the Waiau catchment or gabbroic bodies of southern New Zealand.
Epidote and MnO rich garnets are derived from the Haast Schist Group.
Brown hornblende, enstatite, spinel, clinopyroxene and pyrope garnet are derived from erosion of mantle derived material contained in the Kakanui Mineral Breccia or associated vents. A vent is concluded to occur approximately 4km offshore.
Two sources for glauconite were concluded. Sediment from the Waianakarua River and coastal erosion of the Gees Greensand at Gees Point.
Titanaugite are concluded as being derived from the Dunedin and associated alkalic volcanics of East Otago.

v. 180 p. ill. Photos. 30 cm.

1982Anderson

POLYGON ((170.88 -45.17, 170.92 -45.17, 170.92 -45.21, 170.88 -45.21, 170.88 -45.17))