Red Island (Karamea), Waimarama, Hastings District, Hawke's Bay Region, New Zealandi

Regional Level Types
Red Island (Karamea)	Island
Waimarama	- not defined -
Hastings District	District
Hawke's Bay Region	Region
New Zealand	Country

Stratiform manganese oxide horizons are interbedded between basalt and limestones.

This small island was intensively studied by (Kobe, 1976), is found by walking along the coastline south of Waimarama. It was formed when lava intruded soft seabed calcareous sediments. It is of interest due to its complex geology, containing sedimentary rocks, lavas, zeolites, and manganese horizons. From the base, the rocks units contain the following.

1) Up to 15 metres thick white-grey, bentonitic, partly glaucontitic, calcareous shale or fine sandstone with large calcareous concretions.

2) Up to 4 metre thick pink to dusky red argillaceous limestone and shale, with greenish tuffaceous friable lenses of chlorite, glass shards, and flattened lapilli, with small psilomelane nodules, and dark fine manganiferous matter in rich microfossiliferous beds.

3) Up to 8 metres thick to the east (pinching out to the west) pale olive green lava, with brick red bordering sediments. The lava contains calcite-zeolite filled fractures, and pale orange alteration rims.

4) Up to 10 metres thick greenish black basaltic pillow lava, with black glassy scoriaceous crusts, fractures filled with calcite. Intercalated abundant pink-red calcareous patches.

5) Up to 15 metres thick bluish-green fine grained lava, with white calcite and green chlorite filled veins, an upper dusky red calcareous sediments, and lower brick red, baked, hematitic, and brecciated layer containing psilomelane-pyrolusite nodules.

6) Up to 10 metres thick pink red pillow lava, with baked intercalated calcareous sediments, having pale olive green-grey rusty surfaces, with plagioclase phenocrysts. Fractures are filled with calcite, radiating acicular thomsonite, natrolite, and analcime.

7) An up to one metre thick bright orange ferriferous silaceous bed with abundant radiolaria, with a thin band of manganite and pyrolusite at the base.

8) Uppermost 0.5 metre thick phosphatic argillaceous limestone to shale.

References