50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

More documents

Recommendations

Info

define relationships between, products of the bathymetric data, such as slope, coarse- and finescaled bathymetric position and rugosity. Sediment patterns, catchment areas and channels can be quantitatively identified and traced. In addition, acoustic backscatter intensities returned with the multibeam were processed to identify the broadscale seafloor composition and possible facies distribution. POSTER A DEEP-WATER SHARK FAUNA FROM THE PALEOCENE OF NORTH CANTERBURY Al A. Mannering & Norton Hiller Canterbury Museum, Rolleston Avenue, Christchurch, New Zealand (alman*i4free.co.nz) Apart from the enigmatic Waiparaconus Buckeridge 1983 and the remains of a protopenguin, the Waipara Greensand of North Canterbury is not noted for its macro fossils, but careful searching of exposures along the banks of the Waipara River, at the K/T boundary section and downstream from the Laidmore Road ford, has produced several hundred isolated shark teeth. Preliminary identifications of these remains were provided by the late Ian Keyes, formerly of the Institute of Geological and Nuclear Sciences, who determined that at least seven species were present. The same stratigraphic unit was also investigated in exposures along the North Branch of the Waipara River, close to the confluence with the South Branch. The shark fauna has now been expanded to include eleven genera, several of which are new records for the New Zealand biota. The orthacodontid, Sphenodus Agassiz 1837 has previously been recorded only from the Jurassic of the northern hemisphere and the hexanchid, Chlamydoselachus Garman 1884 from Cretaceous to Recent of Europe, North America, Antarctica and Western Australia. The squalid Megasqualus Herman 1982 is also only known from the Paleocene to Eocene of Europe and Miocene of Japan and California. The odontaspidids Palaeohypotodus rutoti Winkler 1874 and Odontaspis cf winkleri Leriche 1905 have not appeared in any literature associated with New Zealand Comparison with extant species belonging to several of the genera present suggests that the fauna is a deep water one, probably typical of the outer shelf to upper slope. Deep water shark assemblages are quite rare, especially from pre-Miocene deposits, but similar faunas are known from deep water clays of Denmark. This Waipara Greensand fauna will help fill a gap in the poorly known shark faunas of the Paleocene world wide. This conclusion that the assemblage represents deep water is apparently at odds with the interpretation of the Waipara Greensand as having been deposited in a shallow marine setting under conditions of very slow sedimentation (Browne and Field 1985) and requires further investigation. Reference Browne, G.H. and Field, B.D. 1985 The lithostratigraphy of Late Cretaceous to Early Pleistocene rocks of northern Canterbury, New Zealand. New Zealand geological Survey Record 6. 63 pp. POSTER INTRACALDERA LAKE BREAK-OUTS FLOODS: GEOMORPHIC SIGNALS, MECHANISMS, AND HAZARDS V. Manville 1 & K. Kataoka 2 1 Institute of Geology & Nuclear Sciences, Private Bag 2000, Taupo, New Zealand. 2 Research Institute for Hazards in Snowy Areas, Niigata University, Niigata, Japan. (v.manville*gns.cri.nz) Volcano-hydrologic hazards display a wide variety of causative mechanisms, including those directly related to volcanic activity such as explosive ejection of a crater lake, and indirectly-related phenomena such as rain-triggered lahars and breakout floods from temporary lake impoundments. Amongst the latter, events range in scale from relatively minor outflows triggered by failure of crater walls or the breaching of riverine dams composed of pyroclastic, volcaniclastic, or lava flow material to catastrophic floods generated by the breaching of caldera rims. Multiple intracaldera lake breakouts have been identified in several volcanic arcs, including New Zealand, where they exert a major control on drainage patterns, and Alaska, where three out of twelve Holocene calderas have been identified as flood sources. Palaeohydraulic reconstructions indicate such events rank amongst the largest post-glacial floods on Earth, being exceeded only by late Pleistocene deluges associated with breaching of ice-dammed lakes and pluvial basins. Geomorphic and limited published geologic evidence suggests that numerous candidates for similar phenomena lie in Japan and Kamchatka, where the primary focus has hitherto been on physical volcanology and petrology rather than geomorphology and sedimentology. Intracaldera and crater lake breakouts constitute a significant hazard in volcanic environments worldwide, as they may occur without warning, often long after the initial volcanic crisis has subsided, and can devastate 50 th Kaikoura05 -48- Kaikoura 2005
distal alluvial plains where large population centres and infrastructure are typically concentrated. ORAL PAST HIGHSTANDS OF LAKE ROTORUA: IMPLICATIONS FOR TECTONISM AND PALAEOGEOGRAPHY IN THE TAUPO VOLCANIC ZONE V. Manville 1 ,R.Marx 2 ,J.D.L.White 2 1 Institute of Geological & Nuclear Sciences, Private Bag 2000, Taupo, New Zealand 2 Geology Department, University of Otago, PO Box 56, Dunedin, New Zealand. (v.manville*gns.cri.nz) Lake Rotorua currently partially occupies a nearcircular 20 km diameter volcano-tectonic depression formed at 220 ka by eruption of the voluminous Mamaku Ignimbrite. Two distinct lacustrine littoral terraces that fringe much of the lake basin, defined on the basis of contrasting geomorphology and field relationships and separated by tephrostratigraphically dateable unconformities, are here correlated with former highstands of the lake. The first and highest elevation terrace (up to 415 m), corresponds to accumulation of a lake in the newly created basin in the immediate aftermath of the Mamaku Ignimbrite eruption. Considerable uncertainty surrounds the direction of overflow of this level, but the lake may have extended southwards through the Hemo Gorge, a v-shaped notch in the topographic rim of the caldera, through the Ngakuru Graben and into the Waikato River drainage. A highstand at this level would be contiguous with Lake Huka in the Taupo-Reporoa area and require a blockage in the Ongaroto Gorge, possibly related to volcanism at the Ohakuri or Maroa volcanic centres. At some later time a northeasterly outlet became established at a lower level through the tectonically subsiding Tikitere Graben into the Haroharo caldera from where it flowed into the Bay of Plenty via the Kawerau Canyon. The second and most extensive littoral terrace (370-380 m), the post-55 ka Rotoiti alloformation, is the product of a durable highstand produced by blockage of this drainage path by eruption of a voluminous unwelded ignimbrite from the adjacent Okataina Volcanic Centre. Lake level was maintained by stable overspill across a welded ignimbrite sill west of the Tikitere Graben into the north-flowing Kaituna River until accumulation of Mangaone Subgroup tephras in the graben could no longer keep pace with active subsidence. Lake level initially dropped rapidly by c. 20 m as the unconsolidated Mangaone tephras were flushed away, before impingement of the falling lake level on the underlying more consolidated Rotoiti pyroclastics produced a short-lived stillstand at c. 350 m marked by a third alloformation comprising cryptic fluvial strath terraces and shoreline deposits in the Rotorua basin. Resumption of down-cutting triggered an apparently catastrophic break-out through the Haroharo route prior to the 26.5 ka Oruanui eruption and a fall in lake level to below 260 m. Episodic growth of resurgent dome complexes between 21 and 9 ka progressively blocked this drainage path, forcing Lake Rotorua to rise to a level where it could overtop a drainage divide on the northern rim of Lake Rotoiti to reoccupy the former Kaituna River course, establishing the current outlet channel. POSTER PALEOENVIRONMENTAL RECONSTRUCTION OF A WELL- PRESERVED STAGE 7 FOREST SEQUENCE CATASTROPHICALLY BURIED BY BASALTIC ERUPTIVE DEPOSITS, NORTHERN NEW ZEALAND M. J. Marra 1 ,B.V.Alloway 2 &R.M.Newnham 3 1 Department of Geological Sciences, University of Canterbury, NZ 2 GNS-Science, Gracefield Research Centre, PO Box 30368, Lower Hutt, NZ 3 School of Geography, University of Plymouth, Plymouth PL4 8AA, UK (Maureen.marra*canterbury.ac.nz) The well-preserved remnants of a forest sequence, catastrophically inundated by proximal to medial phreatomagmatic deposits, are identified on the shores of the Manukau Harbour. In this study the stratigraphy and age of this forest succession was examined in detail along with palaeoecological proxies (palynology and beetle assemblages) from carbonaceous muds associated with the forest sequence. Optically Stimulated Luminescence dating of the phreatomagmatic deposit together with palaeoecological evidence for interglacial climate suggests deposition in late Marine Isotope Stage (MIS) 7. This extends the known age of Auckland volcanism by up to 40 ka. Ninety-eight fossil beetle taxa were identified. All but two of the fossil taxa occur in the local modern fauna. Based on an extensive survey of the local modern fauna, the fossil beetle fauna represents 48% of families, 20% of genera, and 13% of species in the local modern fauna. The fossil assemblage comprises taxa from forest, wetland and beach habitats. Both beetle and pollen assemblages indicate a kauri/podocarp forest growing adjacent to a wetland on or near a coastal plain. The pollen record shows Agathis australis- dominance between two phases of Dacrydium cupressinum 50 th Kaikoura05 -49- Kaikoura 2005
Page 1 and 2: CHARACTERISATION OF NEW ZEALAND NEP
Page 3 and 4: myrtaceous. One 20 mm diameter flow
Page 5 and 6: ange of lower resolution or fragmen
Page 7 and 8: CRETACEOUS-EOCENE TRANSGRESSION MAR
Page 9 and 10: consists of a well-developed canyon
Page 11 and 12: model. The relative position of the
Page 13 and 14: converts to plate theory. Thus, the
Page 15 and 16: and on the following morning the mi
Page 17 and 18: the LGM grass peak. This period of
Page 19 and 20: offshore west coast to offshore eas
Page 21 and 22: 4 Institut de Recherche pour le Dé
Page 23 and 24: VEGETATION AND CLIMATE CHANGE AT TH
Page 25 and 26: wider range. The youngest layer has
Page 27 and 28: few normal faults visible especiall
Page 29 and 30: TRACKING CRUSTAL DIFFERENTIATION AN
Page 31 and 32: EMPIRICAL SCALING RELATIONS FOR SEI
Page 33 and 34: hydrovolcanic eruptions then took p
Page 35 and 36: and that the MTL marks a Late Carbo
Page 37 and 38: faunal changes within these cores w
Page 39 and 40: material at subsurface depths of se
Page 41 and 42: survived through in low numbers in
Page 43 and 44: in the TVZ and southern Havre Troug
Page 45 and 46: Tephra beds are commonly used to ai
Page 47: The MCC is bounded by deep-seated t
Page 51 and 52: Many of the molluscs in the highly
Page 53 and 54: incremental slip history and paleoe
Page 55 and 56: This paper explores what we know of
Page 57 and 58: volcanism and a linear vent oriente
Page 59 and 60: These areas are also described in
Page 61 and 62: 3D IMAGING OF THE FORE- AND BACKTHR
Page 63 and 64: ascending methane fluids/gases of p
Page 65 and 66: THE GRIFFENS ROAD TEPHRAS: VALUABLE
Page 67 and 68: sideritic concretions that occur in
Page 69 and 70: with 63.8%, and then [3] with 49.9%
Page 71 and 72: U-Th-Ra disequilibria data. In part
Page 73 and 74: landslide tsunami in the past. Rece
Page 75 and 76: core complex mode, temperature driv
Page 77 and 78: truncating three plutonic suites of
Page 79 and 80: active, andesitic White Island volc
Page 81 and 82: and voluminous than at any on Earth
Page 83 and 84: oundaries and with immature source
Page 85 and 86: The new era of commercial viability
Page 87 and 88: TECTONICS OF THE GALATEA BASIN USIN
Page 89 and 90: performed by the electron backscatt
Page 91 and 92: 25km northeast of the volcano. Alth
Page 93 and 94: Most of the tectonic blocks in the
Page 95 and 96: TECTONIC AND NON-TECTONIC CAUSES OF
Page 97 and 98: The continental shelf of the Povert
Page 99 and 100:
5 Dept. of Mineral Sciences, Smiths
Page 101 and 102:
Adams CJ...........................
Page 103 and 104:
Naish T............................
show all

50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?