Completed Student Projects

GNS Science are proud to work alongside many of New Zealand's Universities, and Universities from around the world to provide PhD and MSc funding and supervision of projects. Below we have listed some of our collaborations that have been completed:

Sedimentology and depositional environments of the onshore Jurassic Murihiku Supergroup, Southland Syncline, New Zealand.

Angus Howden, MSc thesis, Victoria University of Wellington, completed 2017

Although a considerable amount is known about the biostratigraphy and organic geochemistry of the Murihiku Supergroup exposed in coastal outcrops of the Southland Syncline, relatively little work has been undertaken on the sedimentology of these rocks. This thesis will examine the reservoir properties based on outcropping sections and determine contrasting styles of Triassic and Jurassic depositional facies. The proposed research will undertake sedimentological and facies interpretations of selected intervals, petrographic and petrophysical analyses, and integrate these with seismic data from the adjacent Great South Basin. This research will give new insights into the reservoir potential of the Murihiku rocks in the Great South Basin and the potential for hydrocarbon exploration.

Seismic line showing the basin fill of the great south basin

The geology of Pegasus Basin based on outcrop correlatives in southern Wairarapa and northeastern Marlborough, New Zealand

Troy Collier, MSc at Victoria University of Wellington (2015)

Troy Collier examines an outcrop in southern Wairarapa

Acquisition of high quality 2D seismic data by the New Zealand Government in 2009-10 (the PEG09 Survey) sparked new interest in Pegasus Basin, an offshore frontier basin situated east of central New Zealand. Although no wells have been drilled in Pegasus Basin, strata exposed onshore in southern Wairarapa and northeastern Marlborough provide useful analogues for the sedimentary fill of the basin.

 Using field observations in combination with petrographic analysis and seismic interpretation, this study provides a more complete understanding of the geology of Pegasus Basin. 13 outcrop localities are described from the surrounding southern Wairarapa and northern Marlborough regions, which are inferred to have been deposited in a range of depositional environments including fluvial, terrestrial and shallow marine deposits, through to inner – mid shelf, and deep marine channel-levee and submarine fans, with fine-grained sedimentation at bathyal depths. These outcrops provide representative and well-exposed examples of facies and lithologies typical of the depositional environments that are likely to exist in Pegasus Basin. Petrographic analysis of six Cretaceous and six Neogene sandstones from Marlborough and Wairarapa regions has revealed that they are compositionally classified as litharenites and feldspathic litharenites, derived from the Torlesse Supergroup. Primary porosity is best preserved in Neogene sandstones, whilst Cretaceous sandstones only tend to preserve secondary porosity, in the form of fractures or dissolution of framework grains. Carbonate cementation, compaction and authigenic clay formation are the biggest contributing factors that degrade reservoir quality.

Seismic interpretation of the PEG09 survey has revealed that Pegasus Basin contains a sedimentary succession over 10,000 m thick, that mantles Early Cretaceous syn-tectonic strata in various states of deformation attained during mid-Cretaceous subduction at the eastern Gondwana margin. Key horizons mapped extensively over the basin highlight seismic reflection packages, which are linked to described outcrop localities onshore, based on reflection characteristics and geometries. The Miocene succession contains up to 4,000 m of sediments that are likely to include promising reservoir lithologies akin to the Great Marlborough Conglomerate of Marlborough, or the Whakataki Formation of Wairarapa.

Characterizing modern stream sediments to better understand reservoir sand provenance, Taranaki Basin, New Zealand

Linda Doran, MS at California State University Northridge, California (2013)

Linda Doran lake

This thesis characterised the modern sedimentary detrital signature of basement terranes cropping out in the Nelson area of the South Island. The same terranes provided sediment to ancient reservoirs in the basin. Modern stream samples provide a representative composition of the detritus being shed from basement terranes and can help us better understand the provenance of ancient reservoir sands. Some mineral species do not survive in the weathering environment whereas others are more durable and persist.

Uniformity of the petrographic point-counting method and grain classification allowed for comparison of basement terranes and the establishment of criteria to discriminate terranes. The method minimised the effects of grain size on detrital modes but some terranes were shown to produce sand fractions (e.g., very fine, fine, medium) with inherently different compositions. Petrographic analysis of different sand size fractions (as opposed to bulk sand samples) provides insight into how the detrital products might fractionate in a given depositional system, for example from distal (finer grained) to proximal (coarser grained) sandstone reservoirs.

The Neogene seismic stratigraphy and uplift history of the offshore Otago-Canterbury shelf, New Zealand

Mike Clark, MSc Victoria University of Wellington (2014)

This study used 2D and 3D seismic data to map Neogene sequence boundaries over the southern offshore portion of the Canterbury Basin. These surfaces were tied to nearby petroleum and IODP wells, to generate a series of isopach maps to document the Neogene evolution of this margin. The maps then serve as input to model the uplift of the Otago shelf using a 3D lithospheric flexure model. The results are presented as depth converted maps of five Neogene sequence boundaries. The maps show the evolution of Neogene sedimentation and provide age constraints to structural events in the basin.

During the Neogene giant progrades extended eastward across the shelf, fed from tectonic uplift in the Southern Alps to the west. The shelf in turn was uplifted by a buoyant load under the lithosphere that can be spatially and temporally linked to the Dunedin volcano. Mapping using two-dimensional seismic reflection data indicates the progressive onlap of the Dunedin Volcano onto a mid-Miocene seismic horizon. This timing is constrained by the 10 Ma age for the last volcanic activity at the Dunedin volcano.

Pliocene isopach map for Canterbury Basin.

Pliocene isopach map for Canterbury Basin.

A study of unconventional gas accumulation in Dannevirke Series (Paleogene) rocks, Canterbury Basin, New Zealand.

Nick Cozens, MSc in Petroleum Geology, Victoria University of Wellington (2011)

This thesis assessed the potential of unconventional gas accumulation in Paleocene-Eocene aged (65-43 Ma) mudrocks in Canterbury Basin. Unconventional hydrocarbon resources are low-porosity, low-permeability rocks with the potential to host large reserves of natural gas. Despite international developments, little is known about New Zealand unconventional hydrocarbon systems.

The deepest part of the Canterbury Basin is located offshore in the Clipper Sub-Basin, where the Cretaceous-Tertiary succession is ~6500m deep. Paleocene-Eocene transgressive rocks intermittently exhibit gas-charged intervals in low porosity facies. These high-gas zones correspond to intervals of elevated quartz, whereas non-gaseous intervals corresponded to relatively low quartz values. The high silica content appears to be related to diagenetic silica origins. Although no visible porosity is observed in thin sections, FMI wireline analysis illustrate natural fractures predominately in siliceous intervals. These lithologies are potential conduits or accumulation intervals for wet gas.

Findings made in this research are compared to the Whangai Formation, considered in this study to be a comparable shale gas system, and also to the Monterey Formation of the United States which is a known basin centred gas system.

Canterbury basin stratigraphy

Outcropping Moeraki (left) and Kurinui (right) formation mudrocks.

Fault growth, tectonic evolution and petroleum migration in the Southern Taranaki Basin, New Zealand

Cathal Reilly, University College Dublin, Ireland.

The Taranaki Basin, mainly west of the North Island of New Zealand, has been faulted in response to differential horizontal motion between the Pacific and Australian plates over the last ~80 Myr. In the southern Taranaki Basin a rich multiphase deformation history has been recorded by 2D and 3D seismic reflection lines. Faulting accommodated extension during the Late Cretaceous to Mid Eocene (~80-45 Ma), followed by contraction in the Late Eocene to Late Miocene (~40-5 Ma) and then by Plio-Pleistocene to Recent back-arc extension (~4-0 Ma). The oldest phase of extension occurred during breakup of Gondwana, while the later contractional and extensional phases of deformation were driven by subduction of the Pacific Plate. Some faults (e.g., Cape Egmont Fault) accrued displacement during each of these phases of deformation.

This study used fault analysis techniques to study fault localisation, reactivation and growth, fault-zone structure and plate boundary evolution. The factors influencing which faults are reactivated, and by how much, were examined along with an investigation into the manner in which growth and death of normal faults and reverse faults differs. The project determined the evolution of deformation in the southern Taranaki Basin and the implications this has for plate boundary deformation. Finally, the project looked at the influence faults have had on the migration and storage of hydrocarbons in the basin.

The project was supervised by Dr. Andy Nicol and Dr. Peter King (GNS Science, Avalon, NZ) and by Prof. John Walsh and Dr. Conrad Childs (Fault Analysis Group, University College Dublin, Ireland)

This project has been funded by GNS Science through New Zealand’s Petroleum Resources programme and by the Fault Analysis Group, University College Dublin.

Relations between faulting, fluid flow, and volcanism in the Taupo Volcanic Zone, New Zealand

Hannu Seeback, University of Canterbury, Christchurch, New Zealand.

The central Taupo Volcanic Zone (TVZ) in the central North Island is currently the most frequently active and productive silicic volcanic system in the world. The TVZ is the present manifestation of arc volcanism which has migrated progressively south and east across the North Island since the Early Miocene in response to changes in the geometry of the subducting Pacific Plate. Inter-arc extension has accompanied arc volcanism since the Late Miocene, with both processes indicating rapid eastward migration in the Late Miocene-Pliocene. The relations between the geometry of the subducting slab, arc volcanism, and inter-arc extension (including the vertical rotation of the Hikurangi margin) are ambiguous and not well understood. Using earthquake, geophysical, and outcrop data this project investigates a range of spatial and temporal scales to better understand the role of faulting and fluid flow in the over-riding and subducting plates and the implications for the location and style of volcanism in the North Island. Funding for this PhD project has come from a GNS Science Sarah Beanland Scholarship and is supervised by Dr. Andrew Nicol (GNS Science, Avalon, New Zealand) and Prof. Jarg Pettinga (University of Canterbury, Christchurch, New Zealand).

Intermediate depth seismicity of the Pacific Plate beneath the North Island. Data: GeoNet earthquake catalogue (1988-2010) ≥ M 3.6

Intermediate depth seismicity of the Pacific Plate beneath the North Island. Data: GeoNet earthquake catalogue (1988-2010) ≥ M 3.6

Seismic facies analysis and tectonostratigraphy of the southern Taranaki Basin, NZ

Jan Baur, PhD in conjunction with Victoria University, Wellington

KupeKerry 3D chimney

This project aims to develop a detailed understanding of the depositional and structural evolution of the offshore southern Taranaki Basin using 2D and 3D seismic reflection data. Seismic attributes are analysed to infer sediment distribution and visualise depositional systems. Acoustic impedance constraints, derived through inversion of seismic data, are used together with seismic attributes and borehole data to classify and estimate seismic facies, petrophysical parameters and lithologies via artificial neural networks. Basin architecture, characteristics and timing of deformation throughout basin history are constrained by structural modelling across various transects, providing the link between tectonic events and sedimentary response. The image above shows a first look at the Maui 3D seismic survey and strata variations seen through various Miocene depth layers.

Evolution and depositional settings of basin floor fan deposits of Lower Mt. Messenger formation of the Late Miocene, Taranaki basin, New Zealand

Larisa Masalimova, PhD in conjunction with Stanford University, California

Taranaki

My PhD thesis research in New Zealand is conducted within the Stanford Project On Deep-Water Depositional Systems under supervision of Donald R. Lowe in collaboration with Geological and Nuclear Sciences (GNS) in New Zealand. The main goal of my research project is to study the sedimentology, geometry, and architecture of deep-water deposits in the lower part of the Miocene Mt. Messenger formation exposed along the western coast of the North Island of New Zealand in the Taranaki region. There are many uncertainties and questions about the depositional setting and provenance of clastic and volcanic sediments in Mt. Messenger Formation. Thus the present study on the lower part of the Mt. Messenger will be based on measurements from grain scale in thin sections and cm-scale measurement of sedimentation units and bed sets from the outcrop to seismic scale examination of the on-to-offshore distribution and character of the sedimentary units. Based on interpretation of this data i will determine depositional settings of the sequences and factors that controlled sedimentation, horizontal and vertical patterns of stacked sediments, the changes in lithofacies and the place of sediment distribution in relation to slope/base of slope/basin floor system.

The evolution of Tertiary normal faults in the Taranaki Basin, New Zealand

Marc Giba, PhD in conjunction with Dublin University, Ireland

Normal faults are widespread within the Taranaki Basin, which is up to 100 km west of the North Island of New Zealand. These normal faults principally accrued displacement during the last 10-15 Myr and formed a regional graben thought to reflect backarc extension driven by subduction of the Pacific Plate. Late Tertiary normal faults may reactivate pre-existing early Tertiary and Cretaceous normal faults. In southern parts of the basin the larger faults remain active today while to the north faults appear to be inactive or moving relatively slowly. The available data suggest that fault activity may have migrated both along and across the graben on million-year timescales. The extent to which such migration occurs and, the geological processes producing temporal changes in fault slip rates, remain important unresolved questions. Using seismic, outcrop and earthquake constraints this project will investigate the origin and nature of migrations in fault activity within an active extensional basin. The research is supervised by John Walsh and Conrad Childs (Fault Analysis Group, University College Dublin, Ireland), and by Andy Nicol (GNS Science, Avalon, New Zealand). The PhD project is funded by a UCD Ad Astra Scholarship and supported by the GNS Science Hydrocarbons Department.

Tectono Volcanic evolution of the late Teriary Taranaki Basin

Active normal faults are shown in black; outlines of active andesitic volcanoes are shown in red on the image above. Andesitic volcanism started in the north of the basin in Mid Miocene times and migrated southwards with Mt Taranaki still being active in the south (A-E). Normal fault activity post-dates volcanism in the north (~4 Myrs later) but also migrated towards the S-SE during Late Miocene-Recent times. Although both volcanism and normal faulting have migrated southwards, this migration is not synchronous and defines slightly different trends. Except for Late Miocene times (B) a close temporal association is, therefore, not observed.

Depositional architecture in a deep-water slope-channel system: Late Miocene Urenui and Kiore Formations, Taranaki Basin, New Zealand

Katherine L. Maier, PhD in conjunction with Stanford University, California

Taranaki

This study integrates multiple scales of data to interpret depositional architectures, stratigraphic patterns, and influences on deposition within the Urenui and Kiore formations. These formations consist of upper Miocene, mid- to upper-slope, deep-water deposits that are imaged in seismic-reflection data and crop out in the Taranaki Basin, New Zealand. Two and three-dimensional seismic-reflection data record prograding clinoforms above a large mass transport complex in an interval broadly correlative to the outcrop. Laterally continuous coastal outcrops of the Urenui and Kiore formations are a heavily bioturbated siltstone sequence with upper Miocene channels preserved at different stratigraphic levels and filled with sandstone and conglomerate turbidites. This study investigates channel formation and architecture, including the association of channels with frequent mass transport deposits and methane-related carbonate concretions. We use detailed measured sections, photomapping, radiometric dating of volcanic ash layers, and horizon mapping of seismic-reflection data. Insight from the Urenui and Kiore formations may be applicable as an analog to other fine-grained deep-water slope systems, including sediments of the underlying Mount Messenger Formation. This study involves PhD research at Stanford University in collaboration with GNS researchers.

Depositional architecture and process sedimentology of the Upper Mount Messenger Formation, coastal Taranaki, North Island, New Zealand

Jonathan R Rotzien, PhD in conjunction with Stanford University, California

Taranaki

I am entering the second year of my PhD at Stanford University in the Stanford Project on Deep-Water Depositional Systems (SPODDS) program under Dr. Donald R. Lowe and Dr. Stephan A. Graham. My current projects aim to understand: 1) the process sedimentology and depositional environment of the Upper Mount Messenger Formation, coastal Taranaki, North Island, New Zealand, 2) the stages of submarine channel evolution and implications for inner levee construction and 3) the grain-size stratification in modern submarine gravity flow deposits, Monterey Canyon, offshore California. This past field season on the Mount Messenger, I measured stratigraphic section, used photopanels to interpret the broader architectural elements and collected samples for thin section, grain size and age analysis. I am in the process of producing and analysing the data from the six weeks of fieldwork. I will use the results to develop testable hypotheses regarding the processes that deposited the Upper Mount Messenger. I’m already looking forward to next field season in Taranaki! When I am not studying rocks, I enjoy exploring the great outdoors, competing for the Stanford cycling and triathlon teams and playing the drums.

Paleogeography of a Mid Miocene turbidite complex, Moki Formation, Taranaki Basin, New Zealand

Sarah Grain, MSc in conjunction with Victoria University, Wellington

Moki Formation, Taranaki

The Moki Formation, Taranaki Basin, New Zealand, is a Mid Miocene (Late Altonian to Early Lillburnian) sand-rich turbidite complex bounded above and below by the massive bathyal mudstone of the Manganui Formation. This study presents an improved palaeogeographic interpretation of the Moki Formation and the younger, Latest Lillburnian / Waiauan-aged, turbidite complex. This interpretation shows that during the Late Altonian, sandstone deposition was localised to small fan bodies in the vicinity of Maui-4 to Moki-1 wells. A bathymetric deepening during the Clifdenian is identified, which appears to have occurred concurrently as the establishment of the Moki Formation fan system, centred around the southern and central wells. With continued sediment supply to the basin floor, the fan system prograded markedly northward and spilled onto the Western Stable Platform during the early Lillburnian. Sand influx to the bathyal basin floor abruptly ceased and large volumes of mud were deposited. By the Waiauan stage, sands were again deposited at bathyal depths on fan bodies and carried to greater depths through a complex bypassing channel system.

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