Structural Background to Hauraki Goldfield Mineralisation: a Review

Abstract

Hauraki goldfield epithermal mineralisation formed in Late Miocene-Early Pliocene time in a calcalkaline arc setting associated with some intra-arc rifting. The country rocks record widespread post-Miocene eastward tilting of the Coromandel peninsula. Some faults show both dip slip and strike slip phases of movement. Mineralisation is restricted to the Mio-Pliocene volcanics and the top of the greywacke basement . Dominant quartz vein trends are northeasterly and dips are sleep, although there are regional and local deviations from these trends. Vein patterns range from simple, planar to complex, stockwork Style of veining and mineralisation are in part controlled by lithology. Some veins appear be tension gashes in dilational jogs, others are localised along faults. Vein fills can be separated into a banded Golden Cross type and a Tokatea type, dominated by buck quartz. Ore shoots in the veins often plunge steeply, possibly indicating control by strike slip faulting.