Evolution of the Mangatete sinter : insights into fault controlled hydrothermal fluid flow

Abstract

The Mangatete sinter, located ~20 km south of Rotorua, is centred on two quarries cut into the footwall of the Whirinaki Fault. The studied quarries, and surrounding 2km x 1.5km region, exhibit evidence of widespread, vigorous, geothermal activity from ~18ka to ~8ka (ages based on AMS 14C dates on opaline sinter and fossil wood). Extensive debris flow breccia throughout the study area contains sinter fragments of distinctive, quartzose stromatolitic textures, and many burnt logs and branches at its base (indicating hot flow), suggesting that hydrothermal activity occurred over a more extensive region, and may have been manifest for much longer. The Mangatete sinters record evidence of geothermal and associated paleoenvironments