late pliocene and quaternary glaciations of new zealand abstract evidence of late pliocene glaciations is fragmentary the ross glaciation in northwest south island is correlated with the first marine faunal evidence of marked cooling in the wanganui basin in southern north island it is inferred to be in the 2 6 2 4 ma age range the porika glaciation in a separate area of northwest south island is younger judged by palynology and is correlated with a cooling 2 2 2 1 ma bp inferred from stratigraphic evidence of lowered sea level in the wanganui basin a gap of 1 5 ma in the record of glaciations is largely filled by wanganui basin marine sediments although an unconformity cuts out the record between ca 1 45 and 1 0 ma bp since then the many sedimentary cycles caused by sea level changes are presumed to be glacio eustatic in origin uplifted interglacial marine terraces back to marine oxygen isotope stage 17 and river terraces formed by cold climate aggradation are linked into the cyclic sequence through loess and tephra in their cover beds east of the south island cores from the dsdp site 594 in the southwest pacific record the earliest glaciation and higher in the core nine periods of south island glaciation in the last 0 7 ma onshore because of uplift and erosion only the last four glaciations assigned to oxygen isotope stages 10 8 6 and 4 2 are identified being named nemona waimaunga waimea and otira glaciations they are best known in north westland northwest south island where the relations of glacial outwash and interglacial shoreline deposits are displayed the late otira glaciation stage 2 is radiocarbon dated as beginning somewhat before 22 3 ka bp culminating ca 18 ka bp and ending at ca 14 ka bp when rapid deglaciation began a relatively small advance at ca 12 ka bp may have been followed by little change until after 8 6 ka bp recession was then followed by a period of advance from ca 5 ka bp until recent centuries and a subsequent recession that still continues

thermochronometry reveals headward propagation of erosion in an alpine landscape glacial erosion of mountain ranges produces spectacular alpine landscapes and by linking climate with tectonics influences a broad array of geophysical phenomena although the resultant landforms are easily identified the timing and spatial pattern of topographic adjustment to pleistocene glaciations remain poorly known we investigated topographic evolution in the archetypal glacial landscape of fiordland new zealand using u th he thermochronometry we find that erosion during the past 2 million years removed the entire pre pleistocene landscape and fundamentally reshaped the topography erosion focused on steep valley segments and propagated from trunk valleys toward the heads of drainage basins a behavior expected if subglacial erosion rate depends on ice sliding velocity the fiordland landscape illustrates complex effects of climate on earth s surface morphology

late pleistocene glaciation of the kosciuszko massif snowy mountains australia abstract late pleistocene glaciation of the australian mainland was restricted to a small area of the southeastern highlands geomorphic mapping of the area and exposure dating using the in situ produced cosmogenic isotope 10be provides evidence for at least two distinct glaciations the early kosciuszko glaciation consisted of a single glacier advance before 59 300 5400 years ago snowy river advance the late kosciuszko glaciation comprised three glacier advances 32 000 2500 headley tarn advance 19 100 1600 blue lake advance and 16 800 1400 years ago mt twynam advance the early kosciuszko glaciation was the most extensive and the late kosciuszko advances were progressively less extensive these periods of glaciation in the highlands correspond to episodes of periglacial activity and peaks in lake levels and river discharge at lower elevations in southeastern australia glacier advances on the kosciuszko massif correlate with advances in tasmania south america and new zealand and are broadly representative of hemispheric climate changes during the last glacial cycle

geomorphic constraints on listric thrust faulting implications for active deformation in the mackenzie basin south island new zealand 1 deformed fluvial terraces preserved over active thrust related folds record the kinematics of folding as fault slip accumulates on the underlying thrust in the mackenzie basin of southern new zealand the kinematics revealed by folded fluvial terraces along the active ostler and irishman creek fault zones are inconsistent with traditional models for thrust related folding in which spatially uniform rock uplift typically occurs over planar fault ramps instead warped and tilted terraces in the mackenzie are characterized by broad continuous backlimbs and abrupt forelimbs and suggest folding through progressive limb rotation by relating this pattern of surface deformation to the underlying thrust with a newly developed simple geometric and kinematic model we interpret both faults as listric thrusts rooted at depth into gently dipping planar fault ramps constraints on the model from detailed topographic surveying of deformed terraces ground penetrating radar over active fault scarps and luminescence dating of terrace surfaces suggest slip rates for the ostler and irishman creek faults of 1 1 1 7 mm yr and 0 5 0 7 mm yr respectively the predicted depth of listric faulting for the ostler fault 0 7 0 2 0 1 km and the irishman creek fault 1 3 0 5 0 1 km generally agrees with geophysical estimates of basin depth in the mackenzie and suggests control of preexisting basin architecture on the geometry of active thrusting despite the potential effects of changes in fault curvature and hanging wall internal deformation the methodology presented here provides a simple tool for approximating the kinematics of surface deformation associated with slip along listric or curviplanar thrust faults

direct correlation of terrestrial and marine paleoclimatic records from four glacial interglacial cycles dsdp site 594 southwest pacific abstract over the last 350 ka changes in the composition of vegetation on new zealand inferred from pollen analysis of the upper 40 m of dsdp site 594 at 2 4 ka sample intervals reflect regional climatic variations which appear synchronous with implied variations in glacier fluctuation and in global climatostratigraphy described from sedimentary and oxygen isotope records from the same samples nelson et al 1985 pollen assemblages from isotope stages 1 5e 7a 7b and 9 are distinguished by conifer and broadleaf forest taxa which vary in composition between the last four interglacials suggesting significant differences in precipitation temperature and or migration rates glacial pollen assemblages which imply the expansion of herbland and decline in forest components show less variation and generally indicate comparatively cool conditions on the east coast of south island interstadial vegetation is composed of a mosaic of shrubland herbland vegetation the close correspondence between variations in the amplitude and timing of these continuous records of forest development in the changing vegetation of south island new zealand and oxygen isotope climatostratigraphy supports previous suggestions that late quaternary southern and northern hemisphere climatic fluctuations were essentially synchronous

δ13c compositions of saturate and aromatic fractions of lacustrine oils and bitumens evidence for water column stratification abstract saturate fractions of oils and source rocks are generally depleted in 13 c relative to the aromatic fraction the isotopic difference between these two fractions aro sat is largest typically in lacustrine oils and bitumens and smallest in marine samples depletions of 13 c in saturate fractions in samples from three lacustrine basins china argentina and u s a correlate strongly with hopane abundance extremely 13 c depleted hopanes have been documented in ancient and modern lacustrine settings and are explained by input from methanotrophic bacteria as these bacteria thrive at the chemocline of stratified lakes extremely 13 c depleted hopanes in geologic samples is evidence for paleostratification comparatively low aro sat values in marine samples are related to abundant sulfate in marine environments since sulfate reducers out compete methanogens for metabolic intermediates and attenuate the methane cycle the strong positive correlation of quantitative hopane abundance with the 13 c depletion in saturate fractions of lacustrine samples provides circumstantial evidence for biogenic input from methanotrophic bacteria and for stratified water columns during source rock deposition further this observation explains why the sofer plot effectively differentiates stratified lacustrine samples from open marine and non stratified lacustrine samples the wide distribution of our sample set suggests that this is a global phenomenon

towards a climate event stratigraphy for new zealand over the past 30 000 years nz intimate project it is widely recognised that the acquisition of high resolution palaeoclimate records from southern mid latitude sites is essential for establishing a coherent picture of inter hemispheric climate change and for better understanding of the role of antarctic climate dynamics in the global climate system new zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the southern hemisphere westerly circulation zone a critical transition zone between subtropical and antarctic influences new zealand has mountainous axial ranges that amplify the climate signals and consequently the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions since 1995 intimate has through a series of international workshops sought ways to improve procedures for establishing the precise ages of climate events and to correlate them with high precision for the last 30 000 calendar years the nz intimate project commenced in late 2003 and has involved virtually the entire new zealand palaeoclimate community its aim is to develop an event stratigraphy for the new zealand region over the past 30 000 years and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from northern hemisphere records e g last glacial maximum lgm termination i younger dryas an initial outcome of nz intimate has been the identification of a series of well dated high resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal yr bp to the present day high resolution records for the last glacial coldest period lgcp including the lgm sensu stricto and last glacial interglacial transition lgit from auckland maars kaipo and otamangakau wetlands on eastern and central north island marine core md97 2121 east of southern north island speleothems on northwest south island okarito wetland on southwestern south island are presented discontinuous fragmentary records comprising compilations of glacial sequences fluvial sequences loess accumulation and aeolian quartz accumulation in an andesitic terrain are described comparisons with ice core records from antarctica epica dome c and greenland gisp2 are discussed a major advantage immediately evident from these records apart from the speleothem record is that they are linked precisely by one or more tephra layers based on these new zealand terrestrial and marine records a reasonably coherent regionally applicable sequence of climatically linked stratigraphic events over the past 30 000 cal yr is emerging three major climate events are recognised 1 lgcp beginning at ca 28 000 cal yr bp ending at termination i ca 18 000 cal yr bp and including a warmer and more variable phase between ca 27 000 and 21 000 cal yr bp 2 lgit between ca 18 000 and 11 600 cal yr bp including a lateglacial warm period from ca 14 800 to 13 500 cal yr bp and a lateglacial climate reversal between ca 13 500 and 11 600 cal yr bp and 3 holocene interglacial conditions with two phases of greatest warmth between ca 11 600 and 10 800 cal yr bp and from ca 6 800 to 6 500 cal yr bp some key boundaries coincide with volcanic tephras copyright 2007 john wiley sons ltd

response of glacial landscapes to spatial variations in rock uplift rate 1 the response of glaciated landscapes to rapid rock uplift driven by tectonic convergence is an important often neglected aspect of proposed interactions between plate tectonic processes and climate change rivers typically respond to more rapid rock uplift in part through increasing channel gradients in contrast the glacial buzzsaw hypothesis suggests that glaciers can erode as quickly as the fastest rock uplift rates 6 10 mm yr without any increase in mean elevations however it has not been established how this is achieved we examined moving window maps swath and longitudinal profiles hillslope relief and hypsometry for glacierized and formerly glacierized basins in areas of spatially variable rock uplift rate in the southern alps new zealand and around nanga parbat pakistan to determine whether glaciers have a specific response to rapid rock uplift the response of these glaciated landscapes to rapid rock uplift 6 10 mm yr comprises 1 modest steepening of the longitudinal profiles in smaller glaciated basins 2 maintenance of shallow downvalley slopes in larger glaciated basins 30 km2 southern alps 100 km2 nanga parbat 3 development of tall headwalls and 4 steepening of the basin as a whole dominated by hillslope lengthening around nanga parbat headwalls several kilometers high constitute 50 of the basin relief at rapid rock uplift rates although glaciers can incise the valley floor swiftly they cannot prevent headwalls from reaching exceptional heights the associated increase in mean distance between cirque heads i e a decrease in drainage density causes regional mean elevation to rise with increasing rock uplift rate however this is much less than the changes in elevation expected in unglaciated ranges

plio pleistocene paleoclimate in the southwest pacific as reflected in clay mineralogy and particle size at odp site 1119 se new zealand clay mineralogical and particle size data from ocean drilling program odp site 1119 reflect processes associated with the deposition of the canterbury drifts and the evolution of the new zealand south eastern shelf and are strongly correlated with pliocene pleistocene climatic and oceanographic fluctuations elevated smectite contents at the base of site 1119 latest early pliocene 3 9 3 5 ma also occur regionally in the southern ocean and point towards an alternative sediment source other than nearby new zealand terranes the abrupt reduction in smectite content at 3 5 ma and replacement by dominant chlorite illite assemblages corresponds to the onset of late pliocene cooling climate conditions and more intense onland physical weathering high illite contents in late pliocene early pleistocene 3 0 1 7 ma sediments suggest a more southern terrane e g haast schist source influence and widened shelf conditions an upward increase in clay content reflects an increased supply of glacier derived detrital sediment concurrent with global climate deterioration during the late pliocene pleistocene grainsize fining of the background mean sortable silt mss signal indicates reduced southland current flow consistent with its forced seaward migration across site 1119 over time due to continual eastward shelf progradation clay mineralogy and particle size data at odp site 1119 exhibit a relationship with both global climatic conditions and with southwest pacific paleoceanographic and paleoclimatic regimes

sediment generation and delivery from large historic landslides in the southern alps new zealand abstract there is much variability of sediment yield in mountain river systems because it is influenced by both periodic e g snowmelt monsoonal circulation and episodic high intensity rainstorms earthquakes controls in the southern alps of new zealand landslides are dominant mechanisms of conveying large amounts of debris to river channels this paper attempts to quantify catastrophic modes of sediment delivery by presenting three recent examples of large landslides on the western slopes of the southern alps a combination of ground surveys dem based volume calculations and air photo interpretation attributes immediate postfailure sediment yields in excess of 70 000 t km 2 a 1 in the short term such landslide derived sediment pulses pose significant hazards to downstream settlements and infrastructure on alluvial fans where they cause massive aggradation increased flooding frequency and large scale channel avulsion in addition to intramontane valley floor obliteration or channel metamorphosis these geomorphic impacts may thus occur far beyond the initial locations of slope failure these catastrophic off site effects involve apparent net sediment delivery rates in the order of 10 5 10 6 m 3 a 1 the accurate quantification of the relative contribution of debris from the disturbing landslide to overall sediment flux is extremely difficult nonetheless are quantitative estimates of landslide derived sediment production and delivery important data to develop a more comprehensive understanding of the variability in alpine sediment flux such data are essential not only for use in hydraulic engineering or catchment management but also in gauging potential future impacts from rainstorm and earthquake induced landsliding in the southern alps

estimating ages of late quaternary stream terraces from analysis of weathering rinds and soils rates of growth of rock weathering rinds and rates of changes of soil morphologic and chemical properties that are calibrated at sites of known ages produce powerful tools for estimating ages of geomorphic surfaces particularly when materials datable by conventional methods are not widespread sequences of latest quaternary stream terraces from the south island of new zealand are ideally suited for application of these calibrated age techniques because climate and source materials for terrace deposits are internally consistent within two regions west land and marlborough modal and mean thicknesses of weathering rinds formed in surface cobbles of torlesse graywacke provide age estimates for latest pleistocene and holocene stream terraces in marlborough with uncertainties estimated at 5 to 40 modal rind thickness of subsurface cobbles provides age estimates for latest quaternary westland sites with uncertainties of 10 to more than 50 few dated soils are available to constrain rates of soil development in westland and marlborough furthermore soils were sampled from only one pedon on each surface morphologic data however provide least squares age estimates for westland sites with uncertainties typically greater than 100 and the calibration data can further bracket likely soil ages to less than 50 uncertainty the regression data from marlborough are less reliable but profile index ratios help bracket ages to at least 50 distributions of oxalate extractable fe and ai and total major element concentrations allow age estimates for westland and marlborough soils with uncertainties estimated at 15 to 50 despite these uncertainties the three techniques combine to provide age estimates with the high resolution needed to examine details of fault slip rates or stream downcutting the calibration data and weathering rates used herein are applicable only to the new zealand region studied although similar calibrated age techniques should provide high resolution dating in many other regions such techniques are particularly useful when multiple approaches are available to provide independent cross checks

rapid creation and destruction of sedimentary basins on mature strike slip faults an example from the offshore alpine fault new zealand abstract seismic reflection profiles and multibeam bathymetric data are integrated to analyse the structure of the 25 km long strike slip dagg basin associated with the marine section of the alpine fault fiordland new zealand the basin is developing in almost 3000 m water depth at a releasing bend whilst contemporaneous transpression results in inversion of its southern end fiord derived glacio marine sediments flooded the basin during the last glaciation and provide a stratigraphic framework for structural analysis geometrical analysis enables an estimation of 450 1650 m of dextral displacement on the alpine fault at the releasing bend since the development of an unconformity estimated to have formed at between 30 and 110 ka this implies a dextral slip rate ranging from a possible minimum of 4 mm yr to the maximum of 35 mm yr constrained by the pacific australian plate motion rate despite total dextral displacement of 480 km on the alpine fault zone and a growth history spanning 15 20 myr this geomorphically well expressed and structurally complex strike slip basin developed and evolved rapidly during the late pleistocene and thus represents only the latest phase in the evolution of the alpine fault upward splaying structures within the fault zone exhibit a rapid spatial evolution in pleistocene strata which may reflect the interactions between high fault slip rate voluminous sedimentation supply inherited structural complexities in the basement rocks and deeper cover sequence and interactions between adjacent faults the present through going releasing bend at the northern end of the basin may have evolved from a more complex pull apart basin that developed between separate segments of the alpine fault the results from dagg basin illustrate the rates at which structural complexities and sedimentary basins can develop within highly active very mature through going continental wrench faults strike slip basins on the scale of 40 80 km 2 on such faults may be ephemeral features that can be developed and destroyed on a time scale of 10 5 10 6 years

linking late pleistocene alpine glacial erosion and continental margin sedimentation insights from 40ar 39ar dating of silt sized sediment canterbury basin new zealand abstract quaternary climatic and eustatic cycles in mid latitude regions have led to more extensive alpine glaciations and continental shelf progradation respectively however the glacial influence on sediment fluxes to the ocean creating continental margin strata is poorly documented this contribution analyzes the provenance of fine sediment accumulating on the continental shelf during the late pleistocene to evaluate the influence of glacial cycles on sediment erosion and routing to the continental shelf taking advantage of the contrasting bedrock ages exposed across the southern alps new zealand we perform 40 ar 39 ar incremental heating on the bulk silt size sediment from three drill sites of iodp expedition 317 canterbury basin new zealand the results suggest that a large proportion of sediment accumulating on the continental shelf results from erosion within the main divide fault zone of the southern alps sediment 40 ar 39 ar age fluctuations over this time period suggest that bedrock with various 40 ar 39 ar cooling ages has been differentially eroded in the upper waitaki river catchment and mixed in the waitaki canterbury sediment routing system across shelf variations in sediment 40 ar 39 ar age reflect changing modes of sediment dispersal on the continental shelf fluvial material likely derived from the main drainage divide zone preferentially accumulates in the middle continental shelf whereas material representing erosion of older bedrock torlesse terrane located lower in the drainage basin is dispersed uniformly across the shelf the age signature of the muddy sediment accumulating on the continental shelf reflects late pleistocene landscape evolution of the southern alps and its influence on sediment dispersal to the continental shelf

luminescence chronology of late pleistocene glacial deposits in north westland new zealand abstract the chronology of the late pleistocene glacial history of north westland south island of new zealand is refined by luminescence dating of sediments it is demonstrated by two case studies that ages determined by different luminescence techniques agree well with the results of radiocarbon dating luminescence ages determined for sediments from two key sites of the loopline formation confirm the previous correlation of this unit with marine isotope stage mis 4 this indicates that late pleistocene glaciers reached their last maximum extent in north westland during the early part of the otira last glaciation furthermore initial dating evidence on coarse alluvial deposits in the lowlands indicates their formation during mis 5b and mis 5d it is probable that these coarse gravel deposits are outwash related to glacial advances if so both advances were probably much less extensive than the glaciations during mis 4 and mis 2

the role of fluvial and glacial erosion in landscape evolution the ben ohau range new zealand a morphometric comparison of valleys has been made for the ben ohau range in the central southern alps of new zealand the range is undergoing rapid tectonic transport and uplift the humid north of the range is a glacial trough and arete landscape with a temperate glacial climate the dry south has rounded divides and plateau remnants dissected by fluvial valleys assuming that space time substitution allows today s spatial valley form transition to represent evolutionary stages in valley development the tectonic history allows time constraints to be placed on the rate of transition to an alpine glacial landscape morphometric change has been quantified using hypsometric curves and distance elevation plots of cirque and valley floor altitudes ancestral fluvial valleys have less concave long profiles but are stepped at altitude owing to the presence of high level cirques and remnant plateau surfaces and possess a low proportion of land area at low elevation increasing glacial influence is manifest as smoother more deeply concave long profiles and u shaped cross profiles associated with a higher proportion of the land area at lower elevation the full morphological transition has involved up to 2 4 km of vertical denudation over the 4 ma lifetime of the mountain range of which 80 per cent would have occurred by preglacial fluvial erosion combining the trajectory of tectonic transport with reconstructed glaciation limits and climatic history it is indicated that about 200 ka of temperate glacial erosion produces recognizable trough and areete topography mean and modal relief increase where glacial activity is confined to cirques but decrease when trough incision by ice becomes established as a dominant process in the landscape 1997 by john wiley sons ltd

late quaternary marine isotope stages 6 1 seismic sequence stratigraphic evolution of the otago continental shelf new zealand abstract a proposed chronostratigraphic model for the late quaternary evolution of the otago continental shelf new zealand includes fluvially incised sequence boundaries eroded during marine isotope stages 2 4 and 6 bounding three sequences subdivided into lowstand transgressive and highstand regressive systems tracts datable material is limited to the uppermost 1 m of the sequence and consequently the model is based on correlation of new high resolution seismic reflection data geopulse to a compilation of independent global sea level curves a second chronostratigraphic model that lacks a stage 4 sequence boundary and distinct stage 3 highstand forced regressive deposit is discounted because its subsidence corrected paleoshoreline depths do not match lowstands in the eustatic curves or temporally constrained sequences at other far field locations in the preferred chronostratigraphic model sea level lowstands during stages 2 4 and 6 reached maximum depths of 126 131 m 101 111 m and 116 135 m respectively producing sequence boundaries landward pinching deltaic wedges on the outer otago shelf and submarine canyon incision lowstand paleoshoreline depths have been corrected for subsidence from thermal cooling sediment compaction and loading but may be erroneously deep owing to erosion of paleoshoreline indicators clastic shallow marine wedges and back barrier valley fill deposits accumulated during the stage 6 5 4 3 and 2 1 marine transgressions contrary to the traditional sequence stratigraphic model deltaic and strandline units deposited during highstand through falling sea level stages 5 4 3 2 1 volumetrically dominate otago late quaternary sequences discrete units and minor marine erosion surfaces within the transgressive and regressive systems tract deposits are interpreted as strong evidence for seventh 20 ka or higher order sea level fluctuations influencing sedimentation on the otago shelf

biological memory of the first pleistocene glaciation in new zealand living species retain memories of their evolutionary history in their dna and that evolutionary history commonly reflects distinct geological events such as mountain building and glaciation we synthesize previously documented genetic data for freshwater fishes and a wide range of upland insect and bird species to document the pliocene and early pleistocene topographic and glacial history of the southern alps of new zealand genetic data for fish suggest that a long linear mountain chain was established in the pliocene at that time the mountain chain had a tectonically constructed narrow topographic neck in the middle with wider uplift zones at either end separation of populations of upland insects and birds into faunal zones at the wider ends was caused by a major glacial advance at the narrow tectonic neck at 2 0 5 ma the composite biological memory constrains the relative timing of uplift of the southern alps as a linear mountain chain with subsequent imposition of temperate glaciation during pliocene pleistocene cooling in the southern hemisphere

upper quaternary marine terrace chronology and deformation south taranaki new zealand an extensive flight of late quaternary marine terraces in the south taranaki region of the north island of new zealand is dated using fission track radiocarbon and amino acid racemization methods a simple model of terrace deformation based on a doming type uplift pattern allows terrace strandline ages to be estimated twelve strandlines are recognized and are estimated to have formed during high sea level stands at 60 000 80 000 100 000 120 000 135 000 210 000 310 000 340 000 400 000 450 000 520 000 600 000 and 680 000 yr b p

loess soil stratigraphy and aokautere ash on late pleistocene surfaces in south westland new zealand interpretation and correlation with the glacial stratigraphy the detailed stratigraphy and chronology for late pleistocene glaciations in north westland have not previously been applied to glacial deposits and landforms of south westland in part because of lack of exposure a stratigraphy for loess coverbeds offers the potential for discriminating and correlating landforms in this region this study in saltwater forest and surrounding areas in south westland confirms the presence of loess and of the incorporated 22 600 bp radiocarbon years aokautere ash beneath late pleistocene moraine and terrace surfaces loess sheets are thin ca 40 cm thick and accretion rates have been low ca 30 mm ka 1 during the last stadial of the last glaciation boundaries between loess sheets were placed at the surface of buried soils paleosols identified from their morphology criteria for recognition of buried soils differ between the moderately well drained moraine sites and poorly to extremely poorly drained terrace sites five loess sheets have been recognised and correlated to the oxygen isotope record on the basis of the position of maximum counts of glass shards of aokautere ash pollen analysis and radiocarbon dates loess sheets 1 and 2 are of last otira glacial age loess sheet 3 accumulated during the last kaihinu interglacial and loess sheet 4 accumulated during the penultimate waimea glaciation loess sheet 5 is of at least waimean age

surface exposure chronology of the waimakariri glacial sequence in the southern alps of new zealand implications for mis 2 ice extent and lgm glacial mass balance during the late quaternary the southern alps of new zealand experienced multiple episodes of glaciation with large piedmont glaciers reaching the coastal plains in the west and expanding into the eastern alpine forelands here we present a new 10be exposure age chronology for a moraine sequence in the waimakariri valley n canterbury which has long been used as a reference record for correlating glacial events across new zealand and the wider southern hemisphere our data indicate that the waimakariri glacier reached its maximum last glaciation extent prior to 26 ka well before the global last glaciation maximum lgm this was followed by a gradual reduction in ice volume and the abandonment of the innermost lgm moraines at about 17 5 ka significantly we find that during its maximum extent the waimakariri glacier overflowed the avoca plateau previously believed to represent a mid pleistocene glacial surface i e mis 8 at the same time the glacier extended to a position downstream of the waimakariri gorge some 15 km beyond the previously mapped lgm ice limit we use a simple steady state mass balance model to test the sensitivity of past glacial accumulation to various climatic parameters and to evaluate possible climate scenarios capable of generating the ice volume required to reach the full local lgm extent model outcomes indicate that under new zealand s oceanic setting a cooling of 5 c assuming modern precipitation levels or a cooling of 6 5 c assuming a one third reduction in precipitation would suffice to drive the waimakariri glacier to the eastern alpine forelands canterbury plains our findings demonstrate that the scale of lgm glaciation in the waimakariri valley and adjacent major catchments both in terms of ice volume and downvalley ice extent has been significantly underestimated our observation that high lying glacial surfaces so far believed to represent much older glacial episodes were glaciated during the lgm challenges the conventional geomorphic model of glaciation in new zealand where the vertical arrangement of glacial landform associations is used to assign successively older glaciation ages

vegetation and climate in southern hemisphere mid latitudes since 210 ka new insights from marine and terrestrial pollen records from new zealand abstract paleo vegetation records developed from marine sedimentary sequences offer considerable potential for examining changes in terrestrial climate beyond the range of 14 c dating because they can be independently dated by 18 o stratigraphy here we present the first pollen record of vegetation from a marine core site in the tasman sea tan0513 14 42 18 s 169 53 e 110 km west of new zealand s south island an independent chronology provided by correlating the globigerina bulloides 18 o record at tan0513 14 to a global isotope stack shows that the record extends back to 210 ka glacial to interglacial changes in palynomorph content are characterised by shrub and podocarp broadleaf forest taxa respectively and are correlated with similar changes in the ca 150 kyr long terrestrial pollen record from okarito pakihi bog 110 km to the south southeast both records are placed on the same timescale by matching variations in dacrydium cupressinum and fuscospora between sites with a unique tie point provided by the ca 25 4 ka kawakawa tephra our southern hemisphere mid latitude vegetation records show forest extent is greatest during periods of low ice volume high mean annual sea surface temperature masst and anti phased with local insolation intensity however there are several features not attributable to changes in mean annual temperature first a fundamental change in forest composition occurred at termination ii tii with a loss of southern beech nothofagus from the study area second the amplitude of masst change through mis 5 is not reflected in corresponding changes in forest extent suggesting other feature s of regional climate seasonality frostiness ice cover exert important controls over vegetation patterns at these latitudes

a cosmogenic 3he chronology of late quaternary glacier fluctuations in north island new zealand 39 s abstract mountain glaciers advance and retreat primarily in response to changes in climate establishing the timing and magnitude of mountain glacier fluctuations from geological records can thus help to identify the drivers and mechanisms of past climate change in this study we use cosmogenic 3 he surface exposure dating and tephrochronology to constrain the timing of past glaciation on tongariro massif in central north island new zealand 39 s exposure ages from moraine boulders show that valley glaciation persisted between c 30 18 ka which coincides with the global last glacial maximum reinterpretation of moraine tephrostratigraphy using major element geochemistry analysis shows that ice retreat and climatic amelioration at the last glacial termination was well underway prior to 14 ka the equilibrium line altitude in central north island during the last glacial maximum was c 1400 1550 m above sea level which is c 930 1080 m lower than present considering the uncertainties in the glacial reconstruction and temperature lapse rates we estimate that this equilibrium line altitude lowering equates to a temperature depression of 5 6 1 1 c relative to present our mapping and surface exposure dating also show evidence for an earlier period of glaciation of similar magnitude to the last glacial maximum which culminated prior to 57 ka probably during marine isotope stage 4 good agreement between the timing and magnitude of glacier fluctuations in central north island and the southern alps indicate a response to a common climatic forcing during the last glacial cycle

variation in soil catena characteristics of moraines with time and climate south island new zealand abstract soil catenas on three moraines in each of two areas with different climate were studied to determine a downcatena soil differentiation with climate and time and b their usefulness in estimating the relative ages of the underlying deposits in the dry area mean annual precipitation map ca 0 5 m all soils have a bw c profiles formed in loess till their similarity in morphology and in most chemical characteristics with catena position and age suggests that the low map does not result in much redistribution of water elements or sediment downcatena this similarity also suggests ages close to each other and correlation with the otiran glaciation oxygen isotope stages 2 and 4 in the wet area map ca 3 m the soils also formed in loess till and with time a soil morphology progresses from a bw c to a e b c h reduced properties intensify especially in the downcatena profiles c citrate bicarbonate dithionite extractable fe displays accumulation in the youngest catena followed by loss in the older catenas and d downcatena trends in total chemical data display marked losses of the more mobile elements these data demonstrate that although catena development is rapid in a wet climate the downcatena contrast can be muted with time due to a change from processes dominated by oxidation to those dominated by reduction soil catena properties in the wet area are sufficiently different to not refute age estimations suggested by suggate 1990 youngest moraine oxygen isotope stage 2 intermediate moraine isotope stage 4 and oldest moraine isotope stage 10 an unresolved problem in both areas is the possibility of soil erosion to foul soil age relations

climate controlled variations in scree production southern alps new zealand the interaction of fluvial glacial and hillslope processes controls the development of mountain belts and their response to tectonic and climatic forcing studies on the contribution of hillslope processes to mountain erosion have focused on bedrock landslides as they have a profound and readily observed impact on sediment yield and slope morphology despite the ubiquity of scree or talus mantled slopes in mountainous terrain the role of frequent low magnitude 100 m 3 rockfall events is seldom addressed in the context of landscape evolution here we quantify the contribution of rockfall erosion across an 80 by 40 km transect in the southern alps new zealand by analyzing the spatial extent of scree slopes mapped from aerial photographs and estimating long term 10 15 k y rockfall erosion rates from the accumulation of slope deposits below bedrock headwalls and in debris and alluvial fans along the rapidly uplifting high rainfall western margin where high rates of bedrock landsliding have been previously documented scree mantled slopes are sparse rainfall decreases exponentially east of the main divide and the proportion of slopes mantled by scree increases monotonically attaining a maximum value of 70 the systematic distribution of scree deposits cannot be attributed to lithologic variation seismicity or the legacy of glaciation instead climate may serve as a primary control on scree production as nearly 70 of the mapped scree deposits in our transect are confined to a narrow elevation range of 1200 1600 m above sea level masl our analysis of altitudinal controls on annual temperature variations indicates that scree production via frost cracking processes may be maximized between elevations of 1600 and 2300 masl as higher elevations are subject to persistent permafrost which obviates the frost cracking process rates of rockfall erosion near the rapidly uplifting main divide are low 0 1 mm yr whereas rates in the scree dominated eastern areas average 0 6 mm yr and may approximately balance rock uplift

evaluation of the relative roles of global versus local sedimentary controls on middle to late pleistocene formation of continental margin strata canterbury basin new zealand determining the relative influence of eustasy versus local sedimentary processes on strata formation is a fundamental challenge in the study of continental margin stratigraphy in this paper the relative contribution of these factors on continental margin evolution during the middle to late pleistocene is evaluated using samples from integrated ocean drilling program expedition 317 core logging biostratigraphy and quantitative x ray diffraction mineralogy are used to delineate continental shelf sedimentary systems major lithological unconformities bound stratigraphic sequences that contain recurring compositional patterns and that resemble other examples of middle to upper pleistocene sequences however a preliminary chronology suggests that sequence boundary formation cannot be linked one to one with eustatic cycles and therefore these sequences can contain multiple ca 100 ka eustatic cycles smaller amplitude higher frequency transitions in sediment composition are interpreted as stratigraphic sequences driven by more rapid perturbations in the interplay of accommodation and sediment supply their stratigraphy is variable in time and across the shelf suggesting a strong influence of local sedimentary forcing in their formation changes in sediment composition after the middle pleistocene transition indicate that sediment transfer from onshore sources in the glaciated southern alps to the middle shelf occurred over a single 100 ka glacio eustatic cycle with an additional 100 ka lag before the mineralogical signal was preserved on the outer shelf this phenomenon is coincident with rapid shelf progradation in this basin suggesting a causal relation between across shelf sediment transport and margin progradation this is one of very few studies that provide insights at the core scale into the processes driving continental margin evolution during the middle to late pleistocene this work shows that compositional changes in mud dominated successions can lead to a sequence stratigraphic interpretation and the identification of high frequency sequences which may not be possible using a conventional stratigraphic approach

new zealand quaternary stratigraphy an overview abstract new zealand quaternary strata including marine sediments loess volcanic and glacial deposits offer detailed records of quaternary environmental change from a geographically significant location time stratigraphic subdivision of new zealand quaternary strata based on marine biostratigraphy and climatostratigraphy has resulted in a series of locally defined stages and substages the plio pleistocene boundary as defined at vrica in italy and dated at ca 1 63 ma lies near the top of the nukumaruan stage in new zealand the first faunal evidence of cooling in new zealand plio pleistocene sequences occurs much earlier at the base of the nukumaruan stage ca 2 4 ma with the appearance in central new zealand of the subantarctic taxa chlamys delicatula and jacquinotia edwardsii although glacial deposits of the south island have long been central to new zealand quaternary stratigraphy they are poorly dated and lack continuity more complete records of quaternary events are found within uplifted marine strata and associated terrestrial deposits of the north island such as in wanganui basin the use of widespread rhyolite tephra for precise correlation and dating in north island offers much for improved land sea correlations direct correlation of on land sequences using tephra with oxygen isotope stages of deep sea cores may negate the need for further local time stratigraphic subdivision in the new zealand quaternary however there will still be scope for regional comparisons highlighting climatic changes not apparent in deep sea cores

a spectral analysis procedure for dating quaternary deep sea cores and its application to a high resolution brunhes record from the southwest pacific abstract date 32 is a fast and easily used computer program developed to date quaternary deep sea cores by associating variations in the earth s orbit with recurring oscillations in core properties such as carbonate content or isotope composition starting with known top and bottom dates distortions in the periodicities of the core properties due to varying sedimentation rates are realigned by fast fourier analysis so as to maximise the spectral energy density at the orbital frequencies this allows age interpolation to all parts of the core to an accuracy of 10 kyrs or about 1 5 of the record duration for a typical brunhes sequence the influence of astronomical forcing is examined and the method is applied to provide preliminary dates in a high resolution brunhes record from dsdp site 594 off southeastern new zealand

late cenozoic exhumation model of new zealand impacts from tectonics and climate abstract late cenozoic convergence between the australian and pacific plates has led to extensive crustal deformation and exhumation in new zealand over the past five decades the convergence associated exhumation history of the palaeozoic mesozoic new zealand basement has been studied using various thermochronometric techniques here we compile 992 published ages and invert them to estimate the temporal and spatial variation in exhumation rates since 25 ma which we then interpret with a plate tectonic reconstruction model the results reveal widespread increases in the exhumation rates at 6 4 ma a time correlated with accelerations in the relative plate motion the absolute increases in exhumation rates are however not uniformly distributed over new zealand since the plio pleistocene the inferred models suggest variable response of exhumation to global cooling in the non glaciated eastern north island the hikurangi subduction margin the million year average exhumation rates have remained relatively low 5 km myr have been observed in the collision zone of the central southern alps of south island where both tectonic deformation and precipitation rates are highest in fiordland the puysegur subduction margin despite the weak crustal deformation the exhumation rates have been high 0 5 3 km myr which we suggest is due to intensified glacial erosion our findings highlight the determining role of tectonics in setting up the regional exhumation pattern but both strong tectonic deformation and efficient erosion are required to maintain rapid exhumation rates the influence of climate on mountain erosion can only be distinguished in regions under slow to mediate exhumation

environmental and sea level changes on banks peninsula canterbury new zealand through three glaciation interglaciation cycles abstract a greater than 200 ka record of marine transgressions and regressions is recorded from a 75 m core from banks peninsula canterbury new zealand this record comprises thick suites of muddy sediments attributed to back barrier lake and lagoonal environments alternating with thin soil and loess complexes these deposits have been dated using radiocarbon and thermoluminescence tl techniques supported by proxy data diatoms phytoliths pollen and sedimentology the aqueous deposits are attributed to three interglacials and an interstadial marine isotope stages 1 5a 5c 6 and 7 the loesses and paleosols date to the intervening stadials isotope stages 2 5d or 6 and probably 8 on the basis of transgressive beach facies back barrier swamps and barrier blocked lake deposits a partial sea level curve including data from isotope stage 5 is presented our data indicate that banks peninsula has been tectonically stable over that period and we provide sea level points that support the existing isotope curve during stages 5 and 6 detailed diatom records are limited to isotope stage 1 and the latter part of stage 5 diatom histories recorded from these stages are remarkably consistent both indicate a progressive floral change from marine types through freshwater colonising species to freshwater planktonic assemblages these reflect parallel histories of coastal evolution during the two interglacials in both cases marine transgression in the early part of the isotope phase was followed by lagoon development implying that a gravel spit extended across the embayment from the west this was succeeded by lake development when the lagoon was cut off by the juncture of the spit with banks peninsula this lake deepened as the coast rotated into swash alignment and the spit was converted into a gravel barrier the vegetation history of the site indicates that mixed podocarp broadleaf forests similar to the pre european flora of banks peninsula occupied the region during isotope stages 1 and 7 this contrasts with the palynological interpretation of a marine record dsdp site 594 from off the canterbury coast which suggested that isotope stage 7 was markedly cooler than the holocene during glacial periods forest was eliminated and replaced by a tall shrubland of mixed montane and coastal affinities

glacial landscape and paleoglaciation in terra sabaea evidence for a 3 6 ga polythermal plateau ice cap abstract in a previous study we demonstrated with a comparative morphometrical analysis the first morphometric evidence of a glacial landscape composed of glacial cirques and glacial valleys in the south of terra sabaea at an elevation 1000 m in two impact craters and one mountain the purpose of this study is to use the same method to seek other geomorphologic evidence of glacial landscapes elsewhere in terra sabaea based on a comparison between current and old glacial landscapes on earth and mars we identified 81 glacial valleys and possible evidence for a former plateau ice cap dated at 3 6 ga at the highest elevation in terra sabaea the identified glacial valleys have the same morphometric properties as terrestrial and martian glacial valleys with u shaped cross sectional profiles a v index 0 2 a length to with ratio 1 and a cross sectional area to drainage area ratio four times higher than the fluvial ones moreover these properties are different from terrestrial and martian fluvial valleys we did not find well preserved glacial cirques in this area this absence questions the origin of glacial valleys however the presence of an extensive flat plateau from which the long valleys radiate could have hosted an ancient plateau ice cap which was the source of these glacial valleys a comparison with the cantal and the shaluli shan in the southeastern tibetan plateau on earth reveals morphometrical similarities with our study area in fact long glacial valleys originating radially from a plateau at higher elevation are characteristics of an ancient plateau ice cap this analysis allowed us to propose a polythermal regime for martian glacial landscape namely a cold based ice cap except at the margin where the regime is warmed based due to the steeper topography this topography created shear stress which increased the heat at the base of the ice and created the outlet glacial valleys near the plateau the radial valleys are u shaped with a v index 0 2 but downstream to the low elevation area these valleys become more v shaped with a v index around 0 1 this hypothesis is supported by the presence of an open basin paleolake making the transition between inlet glacial valleys upstream and an outlet v shaped valley downstream so the morphometry of the radiating valleys suggests that liquid water played a role in the formation of this landscape

glaciation in new zealand the first century of research abstract the year 1965 is seen as the end of a prolonged pioneering stage in new zealand quaternary studies description of evidence of formerly extended glaciers began in 1861 and by 1965 about 138 relevant publications had appeared the following factors and developments in particular influenced directions and progress 1 initially ongoing 19th century interest in the glacial controversy and consequently in ice age manifestations in the large isolated middle latitude islands of new zealand 2 from 1864 vigorous gold mining excavations in quaternary morainic deposits 3 throughout the period domestic disputes about the extent of glacierisation the number and dates of glacial events 4 especially after 1917 consistent extension of sound stratigraphic terminology throughout new zealand 5 in 1944 recognition of evidence for temperature fluctuations in fossiliferous late tertiary pleistocene marine strata in north island with prospects for correlation with south island glacial events 6 after world war ii more overseas contacts and experience giving confidence to those developing independent criteria for distinguishing and evaluating successive ice advances and non glacial interludes 7 also mainly since the war facilities for aerial mapping radiocarbon dating and palynology 8 a new 1 250 000 scale mapping programme by the geological survey begun in 1957 which raised many nomenclatural questions from 1957 internal glacial correlations and progress towards an essentially climate stratigraphic classification culminated in suggate s 1965 scheme embodying a holocene subdivision preceded by four late pleistocene glacial stages with non glacial interludes and by an early pleistocene glaciation despite some correlation problems and questions as to the status of certain intervals the scheme has been widely accepted and used recent work however suggests that the time for substantial revision is at hand

the pleistocene cape kidnappers section in new zealand orbitally forced controls on active margin sedimentation high sedimentation rates in pleistocene active margin basins can provide a very detailed record of tectonic and climatic controls on sediment preservation a 500 m thick pleistocene rock section exposed in northeastern north island of new zealand kidnappers group provides the opportunity to discuss these controls the section is composed of conglomerate sandstones siltstones and minor shales interbedded with tephra layers the sediments were deposited in alluvial to shallow marine environments and preserved in stacks of depositional units decimetres to hundreds of metres thick as a result of base level changes through time the correlation of base level changes in the section with the deep sea oxygen isotope stratigraphy shows that the sequences at 10 m and 80 m scales can correlate respectively to the 20 and 100 kyr changes in eustatic sea level but that the 80 m thick sequences correlate also to changes in tectonic uplift rates a major change in the stratigraphical architecture occurs at the mid pleistocene transition mpt when the 40 kyr ice volume variations shifted to a dominant 100 kyr variation this change includes an increase in the amplitude of the shifts in depositional environments and an overall simplification of the stacking pattern of the depositional units through the mpt this study illustrates that active margin basins can record orbitally forced sedimentary cycles and points to a possible leading influence of eustasy on the pattern of sediment preservation in tectonically active areas copyright 2004 john wiley sons ltd

the glacial sedimentology and geomorphological evolution of an outwash head moraine dammed lake south island new zealand extensive exposures through the glacial landforms around southern lake pukaki new zealand comprise seven lithofacies lfs 1 7 lfs 1 3 are grouped together as lfa 1 pukaki member and record pulsed subaqueous grounding line fan progradation cohesionless debris flows underflow activity and rhythmite deposition by suspension settling iceberg rafting of dropstones and pulsed traction current activity localized disturbance of these deposits by glacitectonic deformation and multi generational hydrofracture fills records minor readvances by the glacier snout and the emplacement of a glacitectonite lf 4 derived from cannibalization of glacilacustrine sediments lfs 4 6 are grouped together as lfa 2 twizel member and record direct glacigenic deposition of glacitectonite lf 4 subglacial traction till lf 5 and supraglacially dumped boulder rubble lf 6 stratigraphic relationships between lfa 1 with lfa 2 record the oscillatory behaviour of the former tasman glacier snout when it formed a calving margin in a proglacial and locally supraglacial lake dammed by a glacitectonically disturbed outwash head and lateral moraine ridges this is entirely consistent with the landform sediment record of its coeval terrestrial margins where flutings and push moraines are diagnostic of active temperate glacier recession from a glacially overridden outwash head the latter being recorded by the vertically stacked sub horizontally bedded and coarse grained gravels of lf 7 waitaki member previous proposals that late pleistocene lake damming was initiated by an ice cored moraine arc appear unfounded because the glacilacustrine deposits only lie above the altitude of the outwash head lateral moraine arc in locations where they have been glacitectonically compressed alternatively it is proposed that the overdeepened subglacial topography was produced by the construction of an outwash head leading to a glacilacustrine sediment sink which operates at times when the expanded tasman glacier actively retreats from the outwash head apex the changing landsystem imprint related to the shrinkage of the tasman glacier records spatio temporal landsystem change involving evolution from a coupled landsystem to a moraine dammed to an uncoupled landsystem

the manawatu aquifers north island new zealand clarification of hydrogeology using a multidisciplinary environmental tracer approach a recently developed approach to carbon isotope methodology process recognition via isotope diagrams is applied in a multidisciplinary study of precipitation recharged aquifers of the lowlands plains area of the manawatu south west north island urban and rural areas rely on groundwater from the upper levels of a deep basin sequence comprising marine and terrestrial sediments of pleistocene age hydrochemical and isotopic 18o 3h 13c and 14c data are merged with known details of geology and hydrogeology to reveal two separate confined aquifers within the depth range to 200 m the shallower of these below unconfined locally recharged groundwater is recharged on the foothills of the ruahine range to the north east of the study area flow direction is ne sw the deeper confined aquifer is recharged on the tararua range to the immediate east flow direction essentially is transverse se nw to that in the shallower aquifer two processes are identified as dominant contributors to concentration and isotopic composition of dissolved inorganic carbon dic namely addition of co2 from decay of organic materials and carbonate dissolution limitations of carbon isotope methods in determining residence times are illustrated by the data although the confined groundwater is essentially tritium free only a few samples showed conclusive evidence of significant ageing on the time scale of 14c copyright 2001 john wiley sons ltd

climate and sea level during oxygen isotope stage 7b on land evidence from new zealand abstract strata at landguard bluff near wanganui new zealand preserve a clear record of relative sea level changes during oxygen isotope stage 7 two relative high sea level stands during stages 7a about 210 000 yr ago and 7c about 240 000 yr ago are separated by a relative low sea level stage 7b that was at least 32 m lower than present pollen analysis of sediment deposited during stage 7b indicates climate at the time was up to 3 c cooler than present the climate and sea level evidence from landguard bluff are consistent with oxygen isotopic evidence from deep sea cores indicating a marked cooling during stage 7 which is closely associated with a summer radiation minimum centered at about 230 000 yr ago in the northern hemisphere

timings and causes of glacial advances across the pep ii transect east asia to antarctica during the last glaciation cycle a comparison of glacial advances through the last glacial cycle between northern and southern hemispheres in the pep 2 transect east asia and australasia revealed 1 a relatively good synchrony of glacial advances during the lgm across the whole transect except antarctica 2 a rough synchrony in glacial advances in the karakorums himalayas japan and new zealand during marine isotope stages mis 3 and 4 although the age control is still poor and 1 a greater glacial extent in mis 3 and 4 than in mis 2 the lgm advances are driven by northern hemisphere temperature forcing but the mis 3 and or mis 4 advances appear to be dominantly controlled by the effects of moisture availability or lack of thereof in mainland australia and antarctica glaciers advanced only in the most humid phases in himalaya and karakorum where the moisture is supplied both by a summer monsoon and the westerlies timings of glacier advance coincide with both summer monsoon enhancement and westerly intensification in japan the glacier extent is controlled by monsoon changes sea surface temperatures ssts in the japan sea moisture source and by zonal shifts in westerly circulation in new zealand either insolalion changes or changes in the intensity of westerly circulation are invoked lis the main track of the westerlies did not change greatly during glacial times c 2003 elsevier ltd and inqua all rights reserved

numerically simulating alpine landscapes the geomorphologic consequences of incorporating glacial erosion in surface process models abstract a numerical model that simulates the evolution of glaciated mountain landscapes is presented by employing a popular sliding based glacial erosion model many common glacial landforms are created the numerical model builds on earlier work as it is fully two dimensional and employs the first order forcing on mountain evolution these forcings include tectonic uplift isostasy hillslope processes fluvial processes and glacial processes a climate dependent model of ice dynamics is employed to determine ice coverage and ice flux two simulations are presented one with generic model parameters and a second with parameters that correspond to conditions in the southern alps of new zealand landforms that are produced by the model include climate climate dependent elevation lowering similar to what might be expected by a glacial buzz saw valley overdeepening terminal moraines and valley retreat the model also predicts that current rates of sedimentation are higher than the long term average and that several tens of thousands of years are required for the landscape to adjust to a change in the dominant erosional forcing therefore glaciated orogens are unlikely to achieve topographic steady state over milankovitch timescales

a new 14 c age for the oruanui wairakei eruption new zealand the oruanui eruption was the largest known outburst of taupo volcano new zealand and is among the larger quaternary eruptions documented the eruption deposits are variously known as the oruanui wairakei kawakawa tephra or aokautere ash formations and represent a bulk volume probably exceeding 500 km 3 four new 14 c age determinations on carbonized vegetation in the non welded oruanui ignimbrite are combined to give a conventional age of 22590 230 yr b p compared with the previously accepted figure of 20000 yr b p this new age resolves the anomaly of apparently older 14 c ages being obtained from a demonstrably younger new zealand deposit and strengthens correlation of this eruption with an antarctic ice core acid anomaly the trace of this eruption has great potential as a time plane marker in the antarctic just prior to the last glacial maximum the close similarity in ages between the oruanui and a comparable sized eruption ito aira tn in japan suggests that this period of activity may represent the best chance of resolving any linkages between large scale explosive silicic volcanism and climate changes

the last glacial maximum lgm in western south island new zealand implications for the global lgm and mis 2 abstract the morainic and outwash deposits of the larrikins la and moana mn formations in north westland are correlated with the m5 t5 and m6 t6 deposits in south westland the la m5 deposits resulted from two separate otira glaciation glacial advances la 1 m5 1 la 2 m5 2 of essentially similar extents pollen sequences in peats and coverbeds extending from before to after the kawakawa tephra 26 500 cal yr bp indicate an extensive period of cold with a slight amelioration beginning shortly before tephra deposition this amelioration which is supported by interpretation of coverbed sequences in south westland separates the la 1 m5 1 and la 2 m5 2 advances the three westland glacial advances la 1 m5 1 la 2 m5 2 and mn m6 culminated at ca 28 000 21 500 and 19 000 cal yr bp the last being followed by major rapid glacier retreat pollen and caco 3 records from dsdp 594 east of the south island reflect contemporary glacier fluctuations on the east side of the southern alps they show the last major cold period as lasting from ca 34 000 to ca 16 000 years ago a period starting before the culmination of the la 1 m5 1 advance and ending later than the beginning of glacier retreat from the mn m6 advance the period from the la 1 m5 1 culmination to the mn m6 culmination represents the lgm in new zealand a slightly longer lgm is recorded in chile and a long lgm may also be indicated in australia a long lgm in the southern hemisphere is supported by the global sea level curve and by the regional antarctic temperature criteria of the vostok ice core these different records indicate a southern hemisphere lgm beginning at least as early as 27 000 years ago much earlier than the ocean last isotope maximum lim from 21 500 to 18 000 years ago the beginning of mis 2 defined primarily from deep sea benthic 18 o at 24 000 years is well after the beginning of ice advances leading to the southern hemisphere lgm a review of global land and ocean correlations is desirable

weathering trends in terrace deposits up to 350 000 years old in northeast southland new zealand abstract gravelly floodplain deposits and six terrace treads in the waimea plains northeast southland new zealand range in age from ca 1000 years old to 350 000 yr old deposits are progressively more weathered with increasing parent material age soils developed in them are classified as recent soils brown soils and ultic soils in the new zealand soil classification and udifluvents dystrochrepts haplohumults hapludults and paleudults in the usda soil classification soil taxonomy the youngest soils are slightly acid those developed in deposits 35 000 70 000 yr old are strongly acid in soils in deposits 160 000 yr old and older that have weathered in two or three interglacial periods including the present one ph and total exchangeable bases values are higher than in soils in younger deposits the higher ph of the soils in older deposits is attributed to release of cations by stone weathering soils developed in deposits up to 70 000 yr old have clays dominated by mica and chlorite stones in these soils are at most weakly weathered and the two phases of weathering are distinguished a phase of approximate duration 100 000 yr in which most weathering and leaching occurs in the matrix which becomes increasingly acidified and a phase from 100 000 to 350 000 yr which is dominated by cation release from stones reversal of the acidification trend and breakdown of stone fabric

rates of active faulting during late quaternary fluvial terrace formation at saxton river awatere fault new zealand a flight of faulted fluvial terraces at saxton river on the awatere fault northeast south island new zealand preserves the incremental slip history and detailed paleoearthquake chronology of this major strike slip fault here six fluvial terraces have been progressively displaced across the inland molesworth section of the fault with horizontal displacements ranging from 6 m for an ephemeral channel on the youngest terrace to 81 m for the riser above the oldest terrace new optically stimulated luminescence ages for abandonment of the two oldest terrace treads are 14 5 1 5 and 6 7 0 7 ka when combined with new measurements of incremental horizontal displacements and previous age data these new ages indicate that strike slip on this part of the awatere fault has been occurring at a near constant rate of 5 6 0 8 mm yr since ca 15 ka this rate is similar to recent slip rate estimates for an adjoining section of the same fault to the east which suggests that there is near complete slip transfer across the junction between the two fault strands comparison of the magnitudes and ages of the terrace riser displacements to the timing of paleoearthquakes on the molesworth section allows the mean per event horizontal displacement over the eight most recent surface rupture events to be estimated at 4 4 0 8 m between ca 5 ka and ca 2 ka surface rupturing earthquakes increased in frequency and decreased in their mean coseismic displacements to 2 6 m during this time the sense of local dip slip also shifted from north side up to south side up rapid incision of saxton river in the mid holocene may have caused a perturbation in the near surface stress directions acting on the fault plane beneath the saxton river valley forcing a change in the near surface fault geometry that resulted in the shift in sense of dip slip

geomorphic evolution of the southern alps new zealand the southern alps are the topographic expression of late cenozoic 8 ma ago uplift of the crust of the leading edge of the pacific plate in south island new zealand new fission track data on the basement exposed in the southern alps quantify the age amount and rate of rock uplift and in combination with geomorphic parameters permit the construction of a new model of the geomorphic evolution of the southern alps the model emphasizes the development over time and space of rock uplift mean surface elevation exhumation of crustal section and relief the earliest indications of mean surface uplift are between 4 and 5 ma ago at the alpine fault mean surface uplift which lagged the start of rock uplift propagated southeastward from the alpine fault at a rate of 30 km ma by about 4 ma ago exhumation had exposed greywacke basement adjacent to and east of the entire 300 km long central section of the alpine fault at 3 ma ago greenschist was exposed in the southern parts of the southern alps near lake wanaka and since then has become exhumed along a narrow strip east of the alpine fault the model infers that amphibolite grade schist has been exhumed adjacent to the alpine fault only in the last 0 3 ma the age of the start of rock uplift and the amount and rate of rock uplift all of which vary spatially are considered to be the dominant influences on the development of the landscape in the southern alps the southern alps have been studied in terms of domains of different rock uplift rate at present the rate of rock uplift varies from up to 8 10 mm a adjacent to the alpine fault to 0 8 1 0 mm a along the southeastern margin of the southern alps this spectrum can be divided into two domains one northwest of the main divide where the present rock uplift rates are very high up to 8 10 mm a and exceed the long term value of 0 8 1 0 mm a and another to the southeast of the main divide where the long term rate is 0 8 1 0 mm a a domain of no uplift lies immediately to the east of the southern alps and is separated from them by a 1 0 1 5 km step in the basement topography we argue that this spatial sequence of uplift rate domains represents a temporal one the existing models of the geomorphic development of the southern alps the dynamic cuesta model of j adams and the numerical model of p koons are compared with the new data and evolutionary model particular constraints unrealized by these two earlier models include the following the earlier timing of the start of rock uplift of the southern alps 8 ma ago the spatial variation in the timing of the start of rock uplift 8 ma ago to 3 ma ago the lower long term rock uplift rate 0 8 1 0 mm a of the southern alps for most of the late cenozoic the lag between the start of rock uplift and the start of mean surface uplift and the patterns of the amounts of late cenozoic rock uplift and erosion across the southern alps

the southern hemisphere westerlies in the australasian sector over the last glacial cycle a synthesis abstract the southern hemisphere westerlies in the southwest pacific are known to have waxed and waned numerous times during the last two glacial cycles though even semi continuous histories of the westerlies extend back no more than about 20 000 years we have good evidence for at least three scales of events a westerly maximum occurs at the last glacial maximum there is less conclusive evidence for another westerly maximum in the late holocene and for a minimum at ca 11 ka it is too early to ascribe even a cycle to these data but there are grounds to suggest that milankovitch precessional forcing may underlie the observed pattern there is also a quasi 2600 year cycle present in antarctic ice cores that appears to correlate to variation in westerly flow there is strong centennial scale variability in historical times the little ice age lia ca 1400 1850 was associated with a poleward shift in the circumpolar trough in the southern ocean strengthened westerly circulation over tasmania and a strengthening of southwesterly circulation and neoglaciation in southern new zealand while the preceding period 800 1400 ad was less certainly marked by reduced westerly flow from modern records we know that decadal and inter annual variability is important e g pacific decadal oscillation high latitude mode also known as the antarctic oscillation el nino southern oscillation only a minority of the proxies examined can identify changes on these temporal scales but data from tree rings ice cores and laminated lake sediments do indicate systematic changes in these phenomena through time rossby wave patterns are shown to play a critical role in long duration events as well as at the synoptic scale we conclude that westerly circulation is as strong now as at any time in the last glacial cycle in addition changes in latitudinal boundaries in the westerlies may be nearly as large in inter annual zonal shifts ca 2 maximum as in glaciation interglaciation movements ca 3 4 there is however reasonable evidence of strengthening weakening across much of the westerly belt at westerly maxima minima such as the lia early holocene

glaciovolcanic emplacement of an intermediate hydroclastic breccia lobe complex during the penultimate glacial period 190 130 ka ruapehu volcano new zealand

late quaternary transgressive regressive sequences from taranaki continental shelf western new zealand abstract interpretation of seismic reflection profiles 3 5 khz airgun and piston core and borehole stratigraphic logs collected from mid outer shelf depths 50 130 m on the taranaki continental shelf western new zealand have delineated at least 4 alternating late quaternary seismic and lithologic couplets each couplet comprises an acoustically transparent upper silty unit that overlies a highly reflective sandy unit characterised by a channelised erosive base radiocarbon and biostratigraphic nannofloral dating of selected samples provides chronostratigraphic control for the succession indicating that the entire sequence is probably late quaternary in age based mainly on nannofossil paleoenvironmental interpretations and seismic reflection characteristics it is proposed that the silty units represent interglacial highstand deposits and that the intervening sandy units were deposited either as glacial lowstand or transgressive nearshore deposits that developed under rising sea level conditions erosive irregular basal unconformities were probably developed during relative sea level fall and represent type 1 sequence boundaries there may also have been a component of wave planation during the subsequent transgression high amplitude channel fill seismic units are possibly fluvial and or paralic sediments deposited during the sea level lowstand and or the ensuing transgression tentative correlation of late quaternary units on the taranaki shelf is made to the deep sea oxygen isotope stage curve to provide temporal resolution of the stratigraphic section four possible sedimentation models are considered based on different temporal interpretations of the observed litho and seismic stratigraphy estimated sedimentation rates for each model are compared to existing data sets as a validation tool the data are inconclusive but appear to support scenario 1 which is characterised by moderate average sedimentation rates over the past 300 000 years typically 0 57 m kyr with an anomalous phase of slow deposition or non deposition and or erosion during stage 6

subdividing the pleistocene using the matuyama brunhes boundary mbb an australasian perspective abstract the last major reversal of the earth s magnetic field the matuyama brunhes boundary mbb dated at 0 78 ma is widely identified in australian and new zealand pleistocene deposits in new zealand the mbb is precisely located in shallow marine sediments of wanganui basin where it corresponds with the base of the new zealand putikian substage a combination of marine biostratigraphy sequence stratigraphy and tephrostratigraphy permit correlation from wanganui basin to other on land sections and deep sea cores in australia the mbb is identified in many continental sequences particularly saline lake basins however chemical weathering has resulted in variable brunhes age normal overprints that are sometimes difficult to remove australasian tektites are a potential lithostratigraphic marker just prior to the mbb but have yet to be identified in the same on land section as the mbb in australia identification of reverse polarity magnetisation in weathered deposits including soils provides a minimum age of 0 78 ma for these materials a widespread arid shift in paleoclimate succeeded the mbb in australia placement of the lower middle pleistocene boundary at the mbb would constitute the most recognisable chronostratigraphic marker in weathered continental deposits

regional insolation forcing of late quaternary climate change in the southern hemisphere southern new zealand positioned within the important southwesterly wind system is a prime site for examining interhemispheric linkages in climate change a series of cores drilled in the okarito pakihi peat bog now provides a continuous record of vegetation and climate change that may become a benchmark for the region the data include clear evidence for modification of the global climate change signal in the southern hemisphere by local variation in the intensity of solar radiation in agreement with the milankovitch orbital forcing hypothesis1 it is often assumed that glacial interglacial climate transitions occurred synchronously in the northern and southern hemispheres of the earth it is difficult to test this assumption because of the paucity of long continuous climate records from the southern hemisphere that have not been dated by tuning them to the presumed northern hemisphere signals2 here we present an independently dated terrestrial pollen record from a peat bog on south island new zealand to investigate global and local factors in southern hemisphere climate changes during the last two glacial interglacial cycles our record largely corroborates the milankovitch model of orbital forcing but also exhibits some differences in particular an earlier onset and longer duration of the last glacial maximum our results suggest that southern hemisphere insolation may have been responsible for these differences in timing our findings question the validity of applying orbital tuning to southern hemisphere records and suggest an alternative mechanism to the bipolar seesaw for generating interhemispheric asynchrony in climate change

correlation of fluvial terraces within the hikurangi margin new zealand implications for climate and baselevel controls abstract a correlation of fluvial terraces is presented for eight non glacial catchments of the eastern north island new zealand within the actively uplifting hikurangi margin using a combination of loess and tephra coverbed stratigraphy and radiocarbon and osl dating of fluvial deposits and loess coverbeds we demonstrate correlation of four fill terraces t1 t4 the available age constraints suggest t1 15 30 ka t2 31 50 ka t3 50 70 ka and t4 115 ka but the association and temporal link with loess deposits suggest correlation with cold periods and thus the refinement of t2 late mis 3 31 40 ka t3 mis 4 55 70 ka t4 mi substage 5b 90 ka 5d 110 ka or mis 6 140 160 ka the ability to correlate terraces between catchments plus the lack of independent evidence for tectonic triggering events indicates terraces have probably formed in response to either climate terrestrial or baselevel sea level control climate control is indicated by the temporal link of post glacial incision with re establishment of forest cover and of lgm aggradation with limited grass and shrub cover and periglacial processes aggradation due to increased sediment supply under reduced vegetation is dramatically demonstrated by formation of the taupo pumice alluvium terrace in response to inundation by volcanic deposits unwelded ignimbrite following the 1 8 ka taupo eruption and the response to post settlement

near synchroneity of new zealand alpine glaciations and northern hemisphere continental glaciations during the past 750 kyr the brunhes magnetochron 0 730 kyr at deep sea drilling project site 594 off eastern south island new zealand comprises up to 100 m of alternating units of pelagic and hemipelagic ooze formed during interglacial and glacial periods respectively the youngest hemipelagic interval corresponds to glacial isotope stage 2 and can be correlated with extensive glacial and glacio fluvial deposits of the late last glaciation 27 13 kyr bp on south island inferring the same genetic link for the other hemipelagic sediment units down core we show here that as many as 12 major episodes of expanded alpine glaciation have occurred on south island in the past 730 kyr each of these glacial episodes coincided with a period of significant 18o enrichment 2 in the core resulting from changes in ocean isotope composition associated with major growth phases of the northern hemisphere ice sheets the inferred history of alpine glaciations on this remote south pacific island appears to be closely phase locked 3 kyr to world wide climate changes

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

the extent and chronology of cenozoic global glaciation abstract the quaternary is synonymous with extensive glaciation of earth s mid and high latitudes although there were local precursors significant glaciation began in the latest eocene ca 35 ma in eastern antarctica it was followed by glaciation in mountain areas through the miocene in alaska greenland iceland and patagonia later in the pliocene e g in the bolivian andes and possibly in tasmania and in the earliest pleistocene e g in the alps new zealand iceland and greenland today evidence from both the land and the ocean floors demonstrates that the major continental glaciations outside the polar regions rather than occurring throughout the 2 6 ma of the quaternary were markedly restricted to the last 1 ma 800 ka or less marine isotope stage mis 22 ca 870 880 ka included the first of the major worldwide events with substantial ice volumes that typify the later pleistocene glaciations i e mis 16 12 10 6 4 2

quantifying bedrock fracture patterns within the shallow subsurface implications for rock mass strength bedrock landslides and erodibility 1 the role of bedrock fractures and rock mass strength is often considered a primary influence on the efficiency of surface processes and the morphology of landscapes quantifying bedrock characteristics at hillslope scales however has proven difficult here we present a new field based method for quantifying the depth and apparent density of bedrock fractures within the shallow subsurface based on seismic refraction surveys we examine variations in subsurface fracture patterns in both fiordland and the southern alps of new zealand to better constrain the influence of bedrock properties in governing rates and patterns of landslides as well as the morphology of threshold landscapes we argue that intense tectonic deformation produces uniform bedrock fracturing with depth whereas geomorphic processes produce strong fracture gradients focused within the shallow subsurface additionally we argue that hillslope strength and stability are functions of both the intact rock strength and the density of bedrock fractures such that for a given intact rock strength a threshold fracture density exists that delineates between stable and unstable rock masses in the southern alps tectonic forces have pervasively fractured intrinsically weak rock to the verge of instability such that the entire rock mass is susceptible to failure and landslides can potentially extend to great depths conversely in fiordland tectonic fracturing of the strong intact rock has produced fracture densities less than the regional stability threshold therefore bedrock failure in fiordland generally occurs only after geomorphic fracturing has further reduced the rock mass strength this dependence on geomorphic fracturing limits the depths of bedrock landslides to within this geomorphically weakened zone

the tekapo glacier new zealand during the last glacial maximum an active temperate glacier influenced by intermittent surge activity abstract quaternary glaciations have created impressive landform assemblages that can be used to understand palaeo glacier extent character and behaviour and hence past global and local glacier forcings however in the southern hemisphere and especially in new zealand the quaternary glacial landform record is relatively poorly investigated with regard to glaciological properties in this study a 1 m digital elevation model dem was generated from airborne lidar data and supplemented with aerial imagery and field observations to analyse the exceptionally well preserved glacial geomorphology surrounding lake tekapo new zealand we describe a rich suite of last glacial maximum lgm and recessional ice marginal subglacial supraglacial glaciofluvial and glaciolacustrine landform assemblages these represent two landsystems comprising i fluted till surfaces with low relief push moraine ridges and ii crevasse squeeze ridges zig zag eskers and attenuated lineations the former landsystem records the behaviour of an active temperate glacier and the latter landsystem which is superimposed upon and inset within the former strongly suggests intermittent surge phases the two landsystem signatures indicate a sequential change in ice marginal dynamics during recession that was likely to have been partially non climatically driven overall we present the first evidence of surge type glacier behaviour in new zealand

late pleistocene glacial stratigraphy of the kumara moana region west coast of south island new zealand abstract on the south island of new zealand large piedmont glaciers descended from an ice cap on the southern alps onto the coastal plain of the west coast during the late pleistocene the series of moraine belts and outwash plains left by the taramakau glacier are used as a type section for interpreting the glacial geology and timing of major climatic events of new zealand and also as a benchmark for comparison with the wider southern hemisphere in this paper we review the chronology of advances by the taramakau glacier during the last or otira glaciation using a combination of exposure dating using the cosmogenic nuclides 10 be and 36 cl and tephrochronology we document three distinct glacial maxima represented by the loopline larrikins and moana formations separated by brief interstadials we find that the loopline formation originally attributed to oxygen isotope chronozone 4 is much younger than previously thought with an advance culminating around 24 900 800 yr the widespread late pleistocene kawakawa oruanui tephra stratigraphically lies immediately above it this formation has the same age previously attributed to the older part of the larrikins formation dating of the larrikins formation demonstrates there is no longer a basis for subdividing it into older and younger phases with an advance lasting about 1000 years between 20 800 500 to 20 000 400 yr the moana formation represents the deposits of the last major advance of ice at 17 300 500 yr and is younger than expected based on limited previous dating the timing of major piedmont glaciation is restricted to between 25 000 and 17 000 yr and this interval corresponds to a time of regionally cold sea surface temperatures expansion of grasslands at the expense of forest on south island and hemisphere wide glaciation