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

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Ma to 1.9 Ma that encompasses Coromandel Peninsula, the Kaimai ranges, Great Barrier Island, and the offshore islands east of the peninsula (except Mayor Island). Volcanic rocks in the CVZ range from basalts, basaltic andesites, andesites, dacites, to rhyolites. Volcanic activity was initiated about 18 Ma along the western Coromandel Peninsula and Great Barrier Island, and involved basaltic-andesite, andesite, and dacite cone volcanism which built up a large portion of the peninsula. This phase of activity lasted until about 12 Ma, when eruptions shifted eastwards and changed to more silicic caldera-forming volcanism that continued until 1.9 Ma as arc volcanism moved from the CVZ to the active Taupo Volcanic Zone (TVZ). Geochemical analyses of a representative suite of rocks from the CVZ by XRF (at the University of Waikato) and ICP-MS (at the University of Texas as Dallas) show that there is a continuous spectrum of compositions in CVZ. They have similar major and trace element compositions to TVZ, apart from the high-K rhyolites (up to 5.5 wt % K2O) which are common as sanidine-bearing rhyolites in the CVZ, but rare in the TVZ. REE patterns in CVZ andesites and rhyolites have moderate slopes (LaN/ YbN average 4 to 8) and moderate Eu anomalies (Eu/Eu* average 0.6 to 0.95). The general geochemical similarities between CVZ and TVZ suggest that they had similar petrogeneses, with the difference that there is a greater proportion of mafic magma in CVZ. ORAL FACTORS INFLUENCING THE DISTRIBUTION OF SUBANTARCTIC DEEP- SEA BENTHIC FORAMINIFERA, SOUTH- EAST OF NEW ZEALAND Ashwaq T. Sabaa 1 , Bruce W. Hayward 1 , Hugh R. Grenfell 1 ,HelenL.Neil 2 1 Geomarine Research, 49 Swainston Rd, St Johns, Auckland 2 National Institute of Water and Atmosphere, P.O. Box 14 901, Kilbirnie, Wellington (a.sabaa*geomarine.org.nz) In this study we investigate the combination of environmental factors that influence the distribution patterns of benthic foraminiferal tests (>0.63 µm) in a topographically varied region crossed by both the Subtropical and Subantarctic Fronts, south-east of New Zealand. Seafloor sample sites extend from outer shelf (50 m) to abyssal (5000 m) depths, are bathed by five different water masses, and receive phytodetritus from Subtropical, Subantarctic and Circumpolar surface water masses. Eight mappable benthic foraminiferal associations are recognised by Q-mode cluster analysis of the census data (>63 �m, 214 species, 68 samples). Canonical correspondence analysis and a correlation coefficient matrix were used to relate the faunal data to a set of environmental proxies. These show that factors related to water depth (especially decreasing food supply with increasing depth) are the most significant in determining the overall foraminiferal distribution. Other contributing factors include surface water productivity and its seasonality, bottom water ventilation, energetic state of the benthic boundary layer and resulting substrate texture, and bottom water carbonate corrosiveness. Three shallow-water associations (50-700 m), dominated by Cassidulina carinata, Trifarina angulosa, Globocassidulina canalisuturata, Gavelinopsis praegeri, andBolivina robusta, occur in coarse substrates on the continental shelf and on the crests and upper slopes of four seamounts under well-oxygenated, high energy regimes, and high food input. Three mid-bathyal to upper abyssal associations (500-3300 m), dominated by Alabaminella weddellensis, C. carinata, and Epistominella exigua, occur in biopelagic sandy mud, beneath a region of strongly seasonal food supply, with composition influenced by total food flux, ventilation (Oxygen Minimum Zone), and bottom current strength. An unusual lower bathyal association (1200-2100 m), dominated by T. angulosa and Ehrenbergina glabra, occurs in a belt of coarser sandy substrates that runs along the crest of the submarine plateaux slopes beneath the strongly flowing Subantarctic Front. A deep abyssal association (3500-5000 m), dominated by Epistominella umbonifera and Globocassidulina subglobosa, occurs on the abyssal plain beneath oligotrophic Circumpolar Water south-east of the Subantarctic Front, and is strongly influenced by cold, carbonate-corrosive, lower Circum-polar Deep Water. ORAL PROVENANCE OF DEVONIAN BEACON SUPERGROUP SEDIMENTS IN SOUTHERN VICTORIA LAND, ANTARCTICA Jeni Savage, Margaret Bradshaw & Kari Bassett Dept. of Geological Sciences, University of Canterbury, Priv. Bag 4800, Christchurch. (margaret.bradshaw*canterbury.ac.nz) Conglomerate beds in the basal part of the Devonian Taylor Group (Beacon Supergroup) in southern Victoria Land provide valuable evidence of provenance and palaeoenvironment. The conglomerates occur within the Sperm Bluff Formation, a unit that overlies an unconformity 50 th Kaikoura05 -76- Kaikoura 2005
truncating three plutonic suites of the Cambrian Granite Harbour Intrusives (Dry Valley 1a & 1b, and DV 2) and their metamorphic country rocks. Provenance analysis was carried out on both sandstones and conglomerates using clast counts, petrographic analysis and U–Pb detrital zircon analysis. Conglomerates are dominated by silicic igneous clasts, mainly rhyolites, and fine-grained quartzites, both of which are unknown in outcrop in southern Victoria Land. Previously recorded granitoid clasts could not be found. Rhyolite clasts have a geochemistry typical of highly evolved subduction-related rocks. Previous workers have dated rhyolite and tuff clasts at between 497±17 Ma and 492±8 Ma, ages that are within error of the Granite Harbour magmatic suites. This suggests that the volcanic clasts came from a co-magmatic volcanic arc rather than a northern Victoria Land source as tentatively proposed by earlier workers. Detrital zircon U–Pb ages for the quartzite clasts suggest derivation from the East Antarctic craton and that the sandstones had been deposited before the Ross/Delamarian Orogeny. Sandstones in the Sperm Bluff Formation are arkosic to quartzose in composition but conspicuously lack plagioclase, indicating significant weathering of a continental source. Detrital zircon analysis gives a strong 500 Ma peak characteristic of Ross/Delamarian orogen magmatic rocks, and consistent with a local source. Basin analysis of the six lithofacies comprising the Sperm Bluff Formation suggest foreshore– shoreface, shallow marine, estuarine and wavedominated deltaic environments. A large delta, or fan-delta, composed partially of easterly-derived conglomerates, as indicated by palaeocurrent directions and channel orientation where the conglomerates are thickest, became buried by marine sandstones during a relative rise in sea level. The presence of pre-Ross quartzite clasts suggests that older continental rocks existed to the east. Westward subduction during the Late Cambrian led to the emplacement of the Granite Harbour Intrusives and their superstructure of rhyolitic volcanoes (DV 1). Dry Valley Suite 2 intrusive rocks and associated volcanic rocks were probably emplaced slightly later in a downfaulted extensional intra-arc basin. This had the effect of preserving the volcanic superstructure in the downfaulted block while the volcanic rocks were being eroded from the upfaulted block to expose the much deeper Granite Harbour Intrusives. Basin inversion during the Devonian caused uplift of the preserved volcanic rocks, supplying rhyolitic and older quartzite clasts to the lower part of the new Beacon Supergroup basin. The basin inversion may have been a far-field effect of tectonic changes indicated by widespread mid-Devonian deformation (Tabberabberan Orogeny) and subsequent granite magmatism in Australia, New Zealand, Antarctica. northern Victoria Land and West POSTER LATE CRETACEOUS EUSTASY AND THE EAST COAST BASIN - THE BAD NEWS! Poul Schiøler 1 , James S. Crampton 2 &MalcolmG.Laird 3 1 Geol. Surv. of Denmark and Greenland, Ø. Voldgade 10, 1350 Copenhagen, Denmark. 2 Inst. of Geol. & Nucl. Sci., PO Box 30 368, Lower Hutt 3 Dept. of Geol. Sci., Univ. of Canterbury, Private Bag 4800, Christchurch. (pos*geus.dk) A palynofacies analysis of four sections through the Paton and Herring Formations of the East Coast Basin in southern Marlborough shows that the two formations were deposited in a marine environment with conspicuous input of plant material from adjacent land area. The Paton Formation was deposited on the inner to mid-shelf under oxic conditions and in proximity to a river delta. The deposition of the Herring Formation took place farther offshore, on the mid-shelf, in a muddominated environment under poorly oxygenated conditions at the sediment/water interface, following a landward shift of shoreline. A stratigraphic analysis of changes in palynofacies and lithology through the four sections allows a breakdown of the succession into seven depositional sequences, separated by unconformities or their correlative conformities. A regional sea-level curve for the Middle Coniacian– Upper Campanian in the East Coast Basin is proposed on the basis of the inferred sequences and chronostratigraphic control from dinoflagellate biostratigraphy. The sea-level cycles thus inferred for the East Coast Basin show a poor correlation with the re-scaled Haq cycle chart, suggesting that regional tectonics rather than eustasy controlled the East Coast Basin sequences. Dinoflagellates (Schiøler & Wilson, 1998; Roncaglia et al., 1999; with modifications from Crampton et al., 2000; and herein) Trithyrodinium suspectum ISZ Nelsoniella aceras IZ Isabelidinium cretaceum IZ Piripauan Odontochitina porifera IZ Conosphaeridium abbreviatum IZ Cymososphaeridium benmorense IZ 50 th Kaikoura05 -77- Kaikoura 2005 NZ stages Upper Haumurian (pars) Lower Haumurian Teratan (pars) Satyrodinium haumuriense IZ Isabelidinium pellucidum IZ Isabelidinium korojonense IZ Vozzhennikovia spinulosa ISZ Chlamydophorella ambigua IZ NS H P Study sections W E KR H P UBM H P BMS H P Regional Sea-level curve, East Coast Basin ?sb 6 HST ?mf 5 LST-TST sb 5 HST mf 4 LST-TST sb 44 HST ?mf 3 LST-TST sb 3 HST mf 2 LST-TST sb 2 LST-HST sb 1 HST ?mf 0 High Low Sea-level curve (Haq et al., 1987 as re-scaled by Hardenbol et al., 1998) Chronostratigraphy (time-scale after Hardenbol et al., 1998) 71.3 Campanian 83.5 Santonian 85.8 Coniacian 89.0 Turonian (part) Ma
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CHARACTERISATION OF NEW ZEALAND NEP
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myrtaceous. One 20 mm diameter flow
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ange of lower resolution or fragmen
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CRETACEOUS-EOCENE TRANSGRESSION MAR
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consists of a well-developed canyon
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model. The relative position of the
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converts to plate theory. Thus, the
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and on the following morning the mi
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the LGM grass peak. This period of
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offshore west coast to offshore eas
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4 Institut de Recherche pour le Dé
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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 and 48: The MCC is bounded by deep-seated t
Page 49 and 50: distal alluvial plains where large
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
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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
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Page 93 and 94: Most of the tectonic blocks in the
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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............................
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