Geology Of The Kaitaia Area

Isaac, M.J. 1996
Geology of the Kaitaia area. Lower Hutt: Institute of Geological & Nuclear Sciences.
Institute of Geological & Nuclear Sciences 1:250,000 geological map 1
44 p. + 1 fold. map

Abstract

The Kaitaia 1:250,000 geological map provides a detailed view of the geology of the northern tip of North Island, New Zealand. It covers a land area of 4200 km² and an offshore area of 23,000 km². This map was created using data from a computerised geographic information system and compiled from detailed 1:50,000 scale geological maps.

Key Features of the Map Area

• Northernmost Region:

  • Consists of isolated rock outcrops connected by the Karikari and Aupouri tombolos, primarily formed of Pleistocene and Holocene dune sands.

• South of the Peninsulas:

  • Dominated by hill country rising up to 300 m above sea level.
  • Features high-standing ranges made of erosion-resistant Cretaceous and Paleocene igneous rocks, with peaks reaching up to 781 m.
  • Includes the Waipoua plateau, formed from Miocene basalt flows.

Geological Highlights

• Basement Rocks:

  • Composed of at least four tectonostratigraphic terranes, though only two are exposed.

• Cretaceous and Paleogene Rocks:

  • Almost all are allochthonous, forming a series of thrust-bounded units (known as the Northland Allochthon) emplaced during Early Miocene time.
  • Coincided with subduction-related andesitic stratovolcanoes, which became extinct by the end of Early Miocene time.

• Post-Miocene Changes:

  • Gradual uplift, arching, and westward tilting of the Northland peninsula have resulted in deep erosion onland.

Geological Resources

The major resources of the Kaitaia map area include:

• Aggregate
• Brown coal (lignite)
• Limestone
• Quartz sand

While onshore hydrocarbon prospects are not highly rated, the Northland Basin (west of the peninsula) is considered highly prospective.

Seismic Activity

• In 1963, three earthquakes caused shaking of MM IV to MM VII in the Kaitaia, Kaeo, and Doubtless Bay areas.
• However, northern Northland has the least seismic activity of any region in New Zealand.

(auth/EB)