QM16 Christchurch
The Christchurch 1:250 000 geological map covers a land area of approximately 9870 km2 in the Canterbury region of the South Island of New Zealand and the Chatham Islands, 850 km further east. It includes foothills of the Southern Alps, basins and ranges of northern Canterbury, Banks Peninsula and part of the Canterbury Plains.The map includes Chatham and Pitt islands and their many outlying islets and reefs. The basement rock of the whole map area is the Torlesse composite terrane - a deformed package of Carboniferous to Cretaceous sedimentary and metasedimentary rocks accreted to the Gondwanaland margin. The constituent Rakaia and Pahau terranes occur in the Christchurch map area, together with the Esk Head belt that is interpreted as a tectonic suture between the two. The only schistose rocks in the map area occur on northern Chatham Island. The greywacke islets of The Forty Fours are the easternmost emergent land of New Zealand.