Desktop study documenting the occurrence and geological characteristics of known VMS deposits associated with Northland's Tangihua Complex

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Brathwaite, R.L.; Christie, A.B.; Lukovic, B. 2012 Desktop study documenting the occurrence and geological characteristics of known VMS deposits associated with Northland's Tangihua Complex. Lower Hutt, N.Z.: GNS Science. GNS Science report 2012/08 43 p. + CD

Abstract: The Tangihua Complex of Northland comprises a series of fault-bounded massifs that contain ophiolite sequences of basaltic pillow lavas with local intercalated siliceous mudstone and micritic limestone, and subvolcanic intrusives of gabbro and dolerite. The intercalated sediments are of Late Cretaceous to Late Paleocene age on limited fossil evidence. The Tangihua Complex contains volcanic massive sulphide (VMS) copper deposits at Pupuke, Pakotai and Parakao that were mined historically. These deposits are associated with sedimentary lenses in the ophiolitic basalt sequences. The Tangihua Complex forms part of the Northland Allochthon, which was obducted by gravity sliding from the north east as a series of thrust sheets in the Early Miocene. Many of the massifs appear to have a similar gross stratigraphy, consisting of a lower part of basaltic pillow lavas with intercalated siliceous and/or calcareous mudstones, overlain by sequences of basaltic pillow lavas and intrusive rocks, within which mudstones are very rare or absent. Low-angle faults, shear zones and broken formation are present throughout the sequences, but are most common where mudstone is relatively abundant. GNS Science was contracted by the Ministry of Economic Development to carry out a desktop study documenting the occurrence and geological characteristics of known VMS deposits associated with the Tangihua Complex. (auth)