Part 3. Present plate boundary and its evolution in the New Zealand region: Mesozoic-middle tertiary tectonic development of Northern New Zealand

Abstract

Northland, that part of New Zealand north of the city of Auckland, is formed in large part from sedimentary rocks belonging to three successive sedimentary associations each of which is accompanied by distinctive igneous rocks. Deposition of the two earlier associations was terminated by brief but widespread periods of deformation at about 90 m.y. and 25 m.y. before present. Deposition in the youngest association ended some 15 m.y. ago, but no clear relationship between this event and deformation has been demonstrated. A brief outline of the rocks that formed during each depositional interval is outlined below and an attempt is made to construct a coherent tectonic history of Northland.