Controls on the formation of large titanomagnetite placers on the west coast of the North Island, New Zealand

Titanomagnetite placers occur as Holocenelate Pleistocene dune and beach sand deposits along the west coast of the North Island, New Zealand. These placer deposits contained large resources of iron ore at Waikato North Head (90 Mt Fe), Taharoa (81 Mt Fe), and Waipipi (8.8 Mt Fe). Mining since 1969 has produced c. 64 Mt of iron from these deposits. Potential economic resources have been identified offshore from Patea (82 Mt Fe) by Trans-Tasman Resources (TTR) and onshore at Aotea (16.5 Mt Fe) by Sinosteel. The main controls on the formation of the deposits are: 1) an abundant supply of titanomagnetite from erosion of Pleistocene-Holocene andesitic volcanic rocks of the Taranaki field, 2) concentration of titanomagnetite by longshore drift and prevailing westerly winds in beach and dune blacksand placers, and 3) trapping and preservation of the placers in coastal embayments and down-faulted depressions.