1 10 2 https://theses.otagogeology.org.nz/files/original/2025f9def560b3a33df6b3293bfb23dc.pdf 508a57f2833dab2364af90c95bf1ebf1 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((172.80671540197298 -41.794420165215051,172.864672968775835 -41.794979677651362,172.85817978703318 -41.851212811696584,172.820471746967627 -41.885952918698258,172.809091794876821 -41.852094942343847,172.806078496049082 -41.794419091878709,172.80671540197298 -41.794420165215051)) Author last name Last name of the Author Hill Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Wilson, G.S Gorman, A.R. Abstract The Abstract for this thesis Glacially overdeepened depressions are ubiquitous throughout the Southern Alps of New Zealand, but their sub-surface extent is poorly understood. They are significant sinks for both catchment drainage and catchment sediment flux, which makes them difficult to characterise, but enticing for scientific study. Their trapped sedimentary sequences contain information about the history of recent glaciations and the rates of landscape erosion under recent climatic conditions. This study has investigated one such depression under Lake Rotoiti, Nelson Lakes, situated in the Northern quarter of the South Island. The approach of this study was to use geophysical methods alongside geomorphic studies, in order to constrain the depth to bedrock, and characterise the sedimentary deposits that have infilled. The following investigations were undertaken: The distributions of surficial sedimentary deposits within the Lower Travers Valley and Black Valley were mapped; a gravity survey was undertaken over the lake-end moraines in order to model their thickness; a single channel seismic reflection survey was undertaken over Lake Rotoiti in order to image the basement surface and overlying sedimentary sequences; the shapes of the bedrock valley walls in the 'trough section' of the Lower Travers Valley were modelled with 2nd - 9th order polynomial equations in order to project their continuation into the subsurface - these were constrained by the geophysical data. The post-glacial deposits within the Lower Travers Valley comprise floodplain fluvial deposits and slope-bottom diamict deposits such as scree, alluvial outwash, landslide and valley-side debris flow deposits. Moraine deposits from 5 different glaciations mostly occur in the St Arnaud region North of Lake Rotoiti. The youngest moraine which bounds Lake Rotoiti has been dated at 14-17 ka (Suggate, 1988b). Gravity modelling of sediment-fill at the lake-ends indicates a substantial sediment thickness. Moraine deposits over some regions are at least 250 m thick. The gravity modelling results indicated that the basement has been glacially overdeepened. The lake is dammed entirely by the 14-17 ka moraine, but a bedrock sill rises to at most 40m beneath the surface 1 km NW of the lake, and is also inferred to rise at the head of Black Valley, 5 km NE of the lake. Seismic reflection data imaged a basement reflector at a minimum depth of 225 m beneath the lake level, and reflectors from the upper surface of the lake-damming moraine. This information was used alongside the gravity constraints and the polynomial models, to construct a coarse, simplistic model of the 14-17 ka glacial erosion surface. By taking the difference between this surface, and the present day topography, it was possible to derive an isopach map of the sediment package that has accumulated since deglaciation, and calculate a volume of 0.67 km3 for this sediment package. This volume estimate was used to calculate a minimum denudation rate of 449-545 tkm-2a-1 (225-273 mmka-1 ) for the Lake Rotoiti Catchment over the last 14-17 kyr. By making some further sediment budget assumptions an upper limit on sediment storage was estimated at 2850 tkm-2a-1 (1173 mmka-1 ). These constraints on denudation indicate that the Lake Roitoit Catchment has been eroding at a much slower rate than higher rainfall regions further south. The Lake Rotoiti Landscape is an example of an older West Coast alpine landscape that is likely to contain more relict glacial erosion features and early paraglacial depositional features than faster eroding catchments further to the South. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Lake Rotoiti Nelson Lakes Nelson Lakes Thesis description Number of pages, maps, CDs, etc. 1 v. (various pagings) : ill., maps ; 30 cm. + 5 sheets + 1 DVD Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2006Hill Creator An entity primarily responsible for making the resource Hill, Matthew Galloway. Date A point or period of time associated with an event in the lifecycle of the resource 2006 Title A name given to the resource Constraining rates of landscape denudation using geophysical models : a case study from Lake Rotoiti, Nelson Lakes, South Island Subject The topic of the resource Geophysics conservation https://theses.otagogeology.org.nz/files/original/68a4a158205e6c698e073dcdca78f192.pdf 6ee39ec7d9de04ed3f6ddea01d256444 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((170.814626820891903 -45.394145807811576,170.814783303516492 -45.405866369096657,170.790638807307147 -45.405973267087838,170.780398843554053 -45.392913894643613,170.781086362911168 -45.375350863375189,170.814542877099228 -45.375281734170912,170.814626820891903 -45.394145807811576)) Author last name Last name of the Author Hill Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Reay, A. Abstract The Abstract for this thesis Introduction There is a curious geological pattern pointing to the fact that silicic volcanism was active during the Late Cretaceous in the South Island of New Zealand. Small localised 110 - 100 M a ago silicic volcanic deposits are found outcropping in Nelson-North Westland, in the Naseby district of North Otago and in the Shag Valley district of NE Otago. This study investigates the Otago silicic volcanic rocks with the purpose of seeing how they compare with each other. Emphasis has also been placed on clarifying the field relations and documenting the lithology of the Shag Valley volcaniclas'1c sediment. 1.1 Geological Setting In both North and East Otago small amounts of Cretaceous silicic tuff are found intercalated within r r the Kyebum and Horse Range formations respectively. These formations consist of thick sequences of breccias and conglomerates which have accumulated in fault depressions that formed under an extensional regime during the Mid to Late Cretaceous. Lower Cretaceous to Early Tertiary marine deposits overWthe Horse Range Formation in East Otago. In North Otago marine transgression reached up into the Maniototo but not as far as the Naseby field locality. A shift to a compressional regime, which has affected the South Island since the early Tertiary, has reactivated Cretaceous normal faults in the reverse sense, producing uplift of basement rocks and the overlying sequences along the NW/SE trending Waihemo Fault Zone (WFZ). The Horse, Kakanui and Ida ranges were formed and these now act as the northern border of the Shag Valley 1 and the M~miototo plains. The NW/SE trending faults mark a change in the Haast schist basement geology where low grade TZ I-ll schists have been uplifted on the northern side above higher grade TZ Ill-IV schist. Figure 1 is a locality map, this shows the location of the two field localities and their relation to the Cretaceous sediments and major faults. The Shag Valley Locality Note that grid references (GR) referring to the Shag Valley locality are from Sheet 143 (NZMS, 1980). The field area is five minutes drive north of Palmerston. It lies within farmland at the foot of the QC Horse Range on the northern side of the lower Shag Valley. A ~trip 1.5 km wide and 2.5 km long, trending NW has been mapped. Nineteen days were spent in the field, the majority of which were spent at two localities. 1.2.1 The Geology On the northern margin of the Shag Valley schists of grade no higher than TZ 11 have been pushed up along faults of the WFZ, forming the Horse Range. Cretaceous sediments of the Horse Range Formation lie north of the WFZ within the Horse Range. These sediments have been uplifted above Horse Range Formation to the south. The latter sediments lie within a fault bounded strip trending NW -SE. These in turn have been uplifted, juxtaposing Cretaceous sediments against Late Tertiary marine sediments. The silicic volcanics outcrop only in this fault bounded strip. As you move outside the field area, within the infaulted strip towards the coast, you move up through the local Tertiary marine sequence. 2 In the first chapter the stratigraphy and structure is briefly presented. It should be noted that lab and field work has not been focussed on these surrounding rocks. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Shag Valley Naseby Thesis description Number of pages, maps, CDs, etc. 60 leaves : ill. (some col.), maps (some col.) ; 30 cm. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 1999Hill Creator An entity primarily responsible for making the resource Hill, Matthew Galloway. Date A point or period of time associated with an event in the lifecycle of the resource 1999 Title A name given to the resource Cretaceous silicic volcanic deposits in the Shag Valley and at Naseby Subject The topic of the resource Volcanology Geochemistry ignimbrite Mineralogy Shag Valley