1 10 2 https://theses.otagogeology.org.nz/files/original/366b7d6c151ed80e5a8fc6952446ba35.pdf a77378c9ef18b835fc9ce237c7d497b2 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 ((170.437735964000012 -43.218165718999956,170.530343838000022 -43.173938119999946,170.613950340000088 -43.133888293999973,170.647860623000042 -43.117611708999959,170.650862966000091 -43.116169698999954,170.6903778410001 -43.097177020999936,170.692535727000063 -43.09613909899997,170.712912034000055 -43.086334669999985,170.725774328000057 -43.080142251999973,170.736275657000078 -43.075084451999942,170.754290751000099 -43.066403482999931,170.787316002000011 -43.050475483999946,170.790037593000079 -43.049162054999954,170.804690317000109 -43.041949072999955,170.811206361000018 -43.038740295999958,170.825166866000018 -43.031863119999969,170.861660674000063 -43.01387,170.875494611000022 -43.007043309999972,170.899441260000117 -42.995218631999933,170.903205965000097 -42.999485708999941,170.912779908000061 -43.010334145999934,170.912951603000124 -43.010528655999963,170.9265565500001 -43.025936718999958,170.936542965000058 -43.037240791999977,170.915565524000044 -43.047658698999953,170.857962564000104 -43.07622669899996,170.852105451000057 -43.079128315999981,170.816090679000013 -43.096957166999971,170.812693708000097 -43.098637666999934,170.788201291000064 -43.110748311999942,170.704350083000122 -43.150371917999962,170.699186898000107 -43.152808032999985,170.630350689000124 -43.185246148999965,170.58122904600009 -43.208347262999951,170.573919751000062 -43.211781420999955,170.569216972000049 -43.213990490999947,170.512330294000094 -43.240683868999952,170.492952775000049 -43.249764566999943,170.489784371000042 -43.25134454099998,170.487572851000095 -43.252447246999964,170.468286022000029 -43.262060475999931,170.442099057000064 -43.275102757999946,170.421689355000012 -43.285259548999932,170.404665164000107 -43.293726095999943,170.368635107000046 -43.311628699999972,170.360440035000124 -43.302781867999954,170.356560604000038 -43.298592811999981,170.354044603000034 -43.295875734999981,170.345622836000075 -43.286778785999957,170.339323458000081 -43.279972197999939,170.333982927000079 -43.274200196999971,170.332350555000062 -43.27243567499994,170.32988604500008 -43.269771410999965,170.37662887700003 -43.247272087999932,170.437735964000012 -43.218165718999956)) Author last name Last name of the Author Wright Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Cooper, A.F. Norris, R.J. Abstract The Abstract for this thesis A 55 kilometre long section of the Alpine Fault was mapped at a 1:25 ,000 scale, from the upper reaches of the Mikonui River in the north, to the northern banlc of the Whataroa River in the south. Recent traces of the Alpine Fault have been identified in 21 locations, some of which yield time-averaged dip-slip and strike-slip rates. The minimum strike-slip rate north of the Waitaha River over the last c.2300 years is 8.4 ± 0.9 rnrn!yr, calculated from the offset of a stream channel across several fault traces. Vertical displacement of the extensive postglacial aggradation surface, across the Alpine Fault zone, was measured in four major river valleys. The age of surface is c.13-14 ka ( calendric ), which provides Holocene-averaged minimum vertical displacement rates of 4.3 - 7.1 mm/yr. Remnants of two uplifted major aggradational fluvial terraces occur on both sides of the Alpine Fault in the Kakapotahi River Valley, the top of the upper terrace being the post-glacial aggradation surface. Assuming a constant vertical displacement rate, the age of the undated lower terrace is 7. 6 ± 1.4 ka. Maximum dextral strike-slip rates calculated from the offset of the terrace risers are 33 ± 8 mm/yr for the upper terrace and 42 ± 9 rnrnlyr for the lower terrace. Substantial small scale variation in the strike and dip of the Alpine Fault plane .is attributed largely to the formation of low angle thrust sheets and the effects of erosion on topography and the resultant stress field. North of the Whataroa River, strike-slip zones linking offset oblique-slip segments are on a scale of 100 m or so rather than the kilometre scale which can be seen further south (c.f. Norris & Cooper 1995). Fault rocks in the footwall are characterised by Fraser Complex gneisses and mylonites, or moraine, overlain by a variable thickness of Quaternary gravel. The hangingwall consists of Haast Schist derived mylonites and cataclasite, with mylonitisation increasing in intensity toward the Alpine Fault. In Kaka Creek, where cataclasite is thrust over river gravel along a fault plane dipping 24° SE. A well exposed section of cataclasite and mylonite in the hangingwall, of at least 350 m true thickness, has foliations typically dipping 45-55° SE. Significant brittle deformation in the hangingwall is limited to within 200 m structurally above the Alpine Fault thrust, and the transition from mylonites to protomylonites occurs between c. 200-250 m from the Alpine Fault. This indicates that the zone of most significant deformation around the Alpine Fault is about 400 m wide at the surface and probably widens out slightly at depth. A band of marble mylonite, 7 m thick in Kaka Creek can be traced discontinuously in the hangingwall for about 23 km along. strike. Extensive carbonate veining of hangingwall rocks occurs in three locations, most notably in a 120 m high exposure in Douglas· Creek. The carbonate is largely dolomitic and contains quartz, pyrite and chalcopyrite. The origin of the carbonate fluid is unknown. North of the Waitaha River, a young fault scarp, cut in schistose alluvial fan gravel and moraine, is exposed in a recently milled podocarp forest at an altitude of 220 m. The scarp uncharacteristically faces southeast with up to 18 m of relative uplift on the north west side. Three sag ponds and a dammed swamp have developed along the downthrown southeast margin of the fault, the largest of which is 70 m long and contains 2.9 m of sediment. Radiocarbon dating of wood from the bottom of sag ponds and from peat horizons from a swamp which has been incrementally dammed by the fault scarp, provide a history of at least five ground rupturing earthquakes on the Alpine Fault in the past 1500 years. Ammal growth vii \ rings in slabs from 25 trees, largely Dacrydium cupressinum (Rimu), which have been selectively, felled along the fault scarp, were analysed for periods of forest-wide reduced radial growth, indicating trauma to the forest by either storms or earthquakes. Dates for four likely periods of strong ground motion since c. 1210 AD were deduced, of which three are consistent with the 14C dates and with dates derived by Yetton et al. (1998). The timing of the last ground-rupturing earthquake at Waitaha was determined as 1720 ± 10 yr AD, consistent with Yetton et al's 1717 AD Toaroha River event. The penultimate ground rupture at Waitaha (here termed the Macgregor Creek event) probably occurred at 1580 ± 10 yr AD, which is. distinct from the 1620 ± 10 yr AD Crane Creek event proposed by Y etton et al. (1998). The Macgregor Creek event, which was accompanied by rockfalls in the central Southern Alps, probably had a rupture length less than c. 100 km. The Alpine Fault has major earthquakes along it every c. 200-300 years and the time elapsed since the last earthquake has been 281 years (to 1998). Displacement on the Alpine Fault probably occurs during single large events. Empirical relationships of earthquake magnitude to fault and rupture parameters restrict the maximum magnitude of an Alpine Fault earthquake to M 7. 8-8 .2, though a series of smaller earthquakes down to c. M 7.1 are possible if segmentation occurs. For a single large earthquake, felt intensities over the South Island would be high, with bedrock intensities in Christchurch being in the region of MM7, and in Dunedin in the region of MM6, depending on rupture directivity and other seismic effects. Local soft-sediment effects would increase the felt intensity by c. 1-3 on the Modified Mercalli intensity scale. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. New Zealand Thesis description Number of pages, maps, CDs, etc. xx, 260 p. : ill. (some col.), maps ; 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 1998Wright Creator An entity primarily responsible for making the resource Wright, Craig A. (Craig Andrew) Date A point or period of time associated with an event in the lifecycle of the resource 1998 Title A name given to the resource Geology and paleoseismology of the central Alpine Fault, New Zealand Subject The topic of the resource Tectoincs Metamorphic petrology Alpine Fault Mikonui River Waitaha River Whataroa River https://theses.otagogeology.org.nz/files/original/de79612ccaa02ea6119cb0b14842e777.pdf 206dc4b2a55eeb9ae4261b60cb8c2d29 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 ((170.442099057000064 -43.275102757999946,170.44502207000005 -43.278173656999968,170.421434206000072 -43.291143788999932,170.418464629000027 -43.292775906999964,170.404665164000107 -43.293726095999943,170.372928227000102 -43.295905167999933,170.360440035000124 -43.302781867999954,170.353563507000104 -43.306567215999962,170.322519862000036 -43.323644735999949,170.317846517000021 -43.319093310999961,170.306279878000055 -43.307824707999941,170.292617982000024 -43.294508121999968,170.31961629500006 -43.279513173999931,170.329325213000061 -43.274117393999973,170.332350555000062 -43.27243567499994,170.33496896500003 -43.270980018999978,170.353544354000064 -43.274545855999975,170.354990999000051 -43.274823416999936,170.364532024000027 -43.276653480999983,170.375682574000052 -43.27879110899994,170.403686116000017 -43.262966338999945,170.421092176000116 -43.248377061999975,170.446544923000033 -43.248860239999942,170.449952314000029 -43.249026593999986,170.458512386000052 -43.249217829999964,170.453607785000031 -43.253149579999956,170.442428166000013 -43.262108943999976,170.439675289000093 -43.27255607099994,170.442099057000064 -43.275102757999946)) Author last name Last name of the Author Read Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Norris, R.J. Abstract The Abstract for this thesis The Alpine Fault south and east of Whataroa consists of two northeasterly striking thrust segments ~8 kilometres long linked by an easterly striking strike-slip segment -6 kilometres long. This structural assemblage is one of the largest geometrical_ irregularities south of the Maruia bend. The geometry of the segmentation requires that the dip of the Alpine Fault at depths of a few kilometres should be greatest near the eastern end of the strike-slip segments where they intersect the southwest ends of the thrust segments. Orientations of the mylonitic foliation, which appear to mirror the Alpine _Fault, are compatible with this requirement, dipping -40° SE at the western end of the strike-slip segment and -56° SE near the southwestern end of the eastern thrust segment. The outcrop distribution of the mylonites is compatible with the suggested segmentation geometry, with higher grade rocks towards the western end of the strike-slip segment. Large scale block rotation is evident within a zone -4 kilometres long and up to several hundred metres across. This zone is bounded to the north by the strike-slip segment striking 080° and to the south by a large fault with a linear trace striking 070°. Foliation within the zone appears to have been rotated 40° in a clockwise sense with respect to foliation to the south of the 070° striking fault. The change in strike occurs within a distance of 5-l 0 metres of the latter fault. Foliation dip does not change abruptly across the fault, suggesting that the rotation occurred about a subvertical axis. The clockwise sense of rotation of the foliation is compatible with a dextral sense of shear between the river flats to the north and the range-front to the south. Foliation strike within 1-2 kilometres of the extrapolated intersection of the western thrust segment and the strike-slip segment swings -37° northward as the intersection is approached from the south and southwest. This change is coupled with a lessening in the dip of -24°. These changes are compatible with gravity driven flexure of the hanging wall as it nears the surface. An approximately 3.5 kilometre long, steeply west-dipping normal fault scarp on the true right of the Whataroa River records collapse of the range front during the late Pleistocene. iii I I I I I I I I I I I I I I I r Most of the feldspars in. the mylonites have both oligoclase cores and rims indicating that: (1) the protolith for the mylonites was oligoclase zone schist, and (2) most of the mylonitisation occurred under oligoclase zone, amphibolite facies conditions. Between -50 and 200 metres away from the Alpine Fault a pod of ultramylonite has been retrogressed. In one of these rocks calcic-albite rims (-An7) around sodic-oligoclase cores ( -An12) indicate that the recrystallisation occurred at the top of the peristerite solvus near the second oligoclase isograd. This indicates that at least some of the mylonitisation occurred unde'r garnet zone, transitional amphibolite facies conditions. c Retrogression of biotite to chlorite occurred under greenschist facies conditions below the biotite isograd in these ultramylonites. The feldspar grains did not re-equilibrate to greenschist facies conditions. Xenoliths of probable Greenland Group in shears around the margins of two granite intrusions suggest that the granitoid intrusions west of the Alpine Fault were intruded into Greenland Group basement. IV I ' ! Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Gaunt Creek Little Man River Whataroa Thesis description Number of pages, maps, CDs, etc. vii, 112, xiv 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 1994Read Creator An entity primarily responsible for making the resource Read, Stephen Edward. Date A point or period of time associated with an event in the lifecycle of the resource 1994 Title A name given to the resource Alpine fault segmentation and range front structure between Gaunt Creek and Little Man River, near Whataroa, central Westland, New Zealand Subject The topic of the resource Structural geology Alpine Fault fluvioglacial deposits Greenland Group Haast Schist Group range front structure Whataroa River