Sedimentology of Hautotara and Te Muna formations, Wairarapa, New Zealand

Abstract

Possible environments of deposition for the Hautotara and Te Muna formations of middle to late Pleistocene time in Wairarapa are described in detail in this thesis. For comparison the underlying upper Miocene to lower Pleistocene coarsening upward (shallowing) marine sediments (Bells Creek Mudstone to Pukenui Limestone formations) were examined. A standard section for the Hautotara Formation is formally described for the first time to supplement the type section which is badly obscured as a result of land conservation work. Data to determine the environments of deposition for the Hautotara and Te Muna formations include grain size analyses, clay mineralogy, sedimentary structures and paleoecology. The Hautotara Formation is partly open coastal marine(beach), partly sheltered estuarine and partly freshwater facies, all deposited during the Marahauan Substage. The overlying Te Muna Formation is fully terrestrial with fluvial gravels, overbank and lacustrine silts, freshwater lignites and lignitic siltstone, subaerial loess and paleosols. Paleomagnetic stratigraphy and tephra indicate a Castlecliffian age (c. 1.0 to 0.4 Myr). Folding of the strata commenced about 1.0 Myrs B.P.