Department of Geology


Simone Hicks

Simone Hicks

PhD Proposal: Ecological and sedimentological evolution of the volcanically active Oligocene continental shelf, east Otago, New Zealand


James White,  Ewan Fordyce, Daphne E. Lee


Otago University PhD Scholarship

International Sedimentology Congress, Mendoza 2010 Poster (5.3MB)

NZGS 2009 Poster (8MB)

NZGS 2008 Poster (10MB)


The Waiareka-Deborah volcanic group are well preserved small relicts of monogenetic, intraplate volcanoes exposed in the North Otago region on the South Island of New Zealand. They erupted around 35 to 30 Ma ago on the submerged continental shelf and formed small Surtseyan volcanoes with an estimated total volume of the order of a few tens of km3. Through the late Eocene to Early Oligocene pillow lavas, hyaloclastite breccias and various pyroclastic and reworked volcaniclastic rocks were deposited in shallow marine basins while contemporaneously limestone and diatomite deposition was taking place. The Waiareka-Deborah volcanics, together with the associated sedimentary and intrusive rocks are members of the Alma Group, which can be found in a triangular area of about 180 km2 with one side along the present coastline of North Otago. The Tertiary marine succession rests on the Upper Cretaceous to Eocene non-marine quartz sands and conglomerates with coal seams, that together rest on a basement of Haast Schist.

The association of the mainly tholeiitic basalt with a substantial volume of mild to high alkaline basalt are complexly interdigitated with bioclastic Ototara Limestone. The interfingering of biogenic and volcanogenic strata occurred throughout Kaiatan, Runangan, and earlier Whaingaroan times (~ 37 - ~ 32 Ma). The end of the Alma Group is marked by a widespread mid-Oligocene hiatus, called the Marshall Paraconformity, a regionally significant surface of erosion or non-deposition in the South Island.


The geology of the Oamaru District has generated notable interest among geologists. Many papers have been written, and the Alma Group has been the subject of much discussion since first described by Mantell in 1850. Many works on the geology of the Alma Group have concentrated on mapping, micropaleontology, chronostratigraphy, macroscopic facies analysis and volcanism. A number of issues related to the volcanism and the biological response are still to be investigated. A major target of this thesis is to provide an overview study along with implications for paleoceanography and basin development considering the relationship among marine organisms, sediment accumulation, volcanism and ocean currents for the Oligocene continental shelf of eastern Otago. To this end, I am studying the physical sedimentology of the bioclastic limestones, and their stratigraphic relationships with marine volcaniclastic strata. In addition, analysis of the stable-isotopic signatures of the calcareous sediment will provide information on the oceanic water masses and their evolution during this pivotal period in the evolution of the Southern Ocean and the southeast-central part of the largely submerged Zealandia landmass.

Overview of the field area of this study along the East coast of North Otago, South Island, New Zealand.

Cape Wanbrow/Boatmans Harbour near Oamaru

(Northern) Section at Cape Wanbrow/Boatmans Harbour showing bedded tuffs and cross stratification

Pillow lavas

Pillows at Boatman's Harbour with limestone occupying the interstices

Bioturbated tuff

Bioturbated tuffs at Cape Wanbrow


Serripecten in Gees Greensand at Gees Point

Foraminifera Nodosaria

Foraminifera Nodosaria in Gees Greensand at Gees Point

Minerals in the Kakanui Mineral Breccia at Kakanui South



Altered Lherzolite nodule with chrome diopsite


Garnet clinopyroxenite

Prismatic hornblende

Prismatic hornblende

Polished hornblende

Polished hornblende

Pyroxene H







Previous work...

Abstract Diploma Thesis 2005:

"Palaeoecology of the macro benthos of the Upper Jurassic (Kimmeridgian) in the Kanton Jura, northern Switzerland".


The aim of this study was the taxonomic classification and palaeoecological analysis of an Upper Jurassic marine macro benthic fauna from the Banné Marls near Porrentruy, northern Switzerland. The study was for a diploma-thesis at the Institute of Palaeontology, Julius-Maximilians-Universität Würzburg, Germany. The habitat of potential palaeo-communities of the macro benthic organisms was reconstructed, and related to environmental parameters such as salinity, substrate consistence and water depth. The bulk samples for the study of the fossils and their habitat were collected at “La Combe de Vâ tche Tchâ” (VTT), in the western Swiss Tabular Jura, northwestern Switzerland.

The broader setting represents a shallow epicontinental marine depositional environment with a periodically fluctuating sea level. The slightly nodular Banné Marls comprise grey dm-thick layers of marlstone, calcarenitic marls and marly limestones with a rich fauna of bivalves, gastropods, some brachiopods, nautilids, echinoids and vertebrate remains. Analyses revealed a soft ground, bivalve-dominated, infaunal, filtrating autochthonous fully marine benthic palaeocommunity. Apart from some individual fluctuations of low diversity taxa the environment was nearly stable.

VTT = La Combe de Vâ tche Tchâ

Litho-, chrono- and biostratigraphic position of the Reuchenette Formation and the Banné-Marls in the Kanton Jura.

Geological map with Schweizer Tafeljura and position of sample location (VTT)

Conference Posters

 International Sedimentology Congress, Mendoza 2010


Click on poster to download/view fullsize pdf (5.3MB)

NZGS 2009 Conference Poster

NZGS Conference Poster 2009

Click on poster to download/view fullsize pdf (8.3MB)

NZGS 2008 Conference Poster

NZGS 2008 Poster

Click on poster to download/view fullsize pdf (10.6MB)