Geology of the Weber region, North Island, East Coast, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science, School of Agriculture and Environment
Geological mapping of the East Coast Basin has tended to be at a broad scale with detailed mapping
confined to a few specific areas of interest. The East Coast Basin is a petroliferous region and therefore of
interest for petroleum exploration, however, further detailed mapping and sedimentological research is
needed to have a better appreciation of the reservoir potential of the basin. Mapped geological boundaries
are inferred based on broad tectonic features and structures, and little sedimentology has been undertaken.
The current geological understanding is that this area contains a succession of Late Cretaceous (70 Ma) to
Late Miocene (~5 Ma) sandstone, limestone, marl, flysch and mudstone facies. Few potential reservoir
units are mapped or received detailed analysis and source rock has been an ongoing enigma due to known
oil and gas seeps but low Total Organic Content results in most previously studied samples.
The purpose of this research is to produce a high- resolution 1:25 000 geological map and undertake
biostratigraphical, petrological, structural and paleo-environmental studies to help differentiate the
Miocene aged geology of the area.
Findings indicate the area is structurally complex with many faults, folds, including the Akitio Syncline,
and local unconformities. Within the stratigraphic sequences identified both macro and micro fauna
provide depositional environment and age control. Sedimentological and petrographic analysis of the
major units also indicate variability in depositional environments from abyssal to shallow marine. Key
areas have been located to provide accurate ages throughout the depositional sequence. This project will
contribute to current research on the petroleum reservoir potential of the East Coast Basin.
The following Figures were removed for copyright reasons: 1.1, 3.2 (=Bailleul et al., 2013 Fig 12) and 3.3 (available at https://researcharchive.vuw.ac.nz/xmlui/handle/10063/7715). Adapted Figures remain for the sake of clarity. Possibly copyrighted material in the Appendices remains for ease of access.