Geology of the Kaitaia area : scale 1:250,000 Digital Download

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Isaac, M.J. 1996 Geology of the Kaitaia area : scale 1:250,000 Institute of Geological & Nuclear Sciences 1:250,000 geological map 1 

Abstract: The Kaitaia 1:250,000 geological map covers a land area of 4200 km2 at the northern tip of North Island, New Zealand, and also shows 23,000 km2 of the adjacent area offshore. The map has been drawn using data held on a computerised geographic information system and was compiled from more detailed 1:50,000 scale geological maps. The northernmost part of the map area consists of several isolated rock outcrops linked to each other and to the remainder of the North Island by the Karikari and Aupouri tombolos, which are formed mainly of Pleistocene and Holocene dune sands. South of the dune-dominated peninsulas, northern Northland is for the most part hill country up to 300 m above sea level, upon which are superimposed high-standing ranges formed of erosion-resistant Cretaceous and Paleocene igneous rocks with peaks up to 781 m high, and the partly dissected plateau at Waipoua, which is formed of Miocene basalt flows. The basement rocks of Northland consist of at least four tectonostratigraphic terranes, but only two are exposed. Almost all the Cretaceous and Paleogene rocks exposed onshore are allochthonous, and comprise a series of thrust-bounded units (Northland Allochthon) which was emplaced in Early Miocene time. Emplacement of the Northland Allochthon coincided with the eruption of large, subduction-related andesitic stratovolcanoes. The volcanoes became extinct by the end of Early Miocene time. Since then, gradual uplift, arching, and westward tilting of the Northland peninsula have resulted in deep erosion onland. The major geological resources of the Kaitaia map area are aggregate, brown coal (lignite), limestone, and quartz sand. Though hydrocarbon prospects onshore are not rated highly, the Northland Basin west of the Northland peninsula is highly prospective. In 1963, three earthquakes produced shaking of MM IV to MM VII in the Kaitaia, Kaeo, and Doubtless Bay area, but northern Northland has the least seismic activity of any New Zealand region. (auth/EB)