long term behaviour of australian stable continental region scr faults abstract australia boasts arguably the richest late neogene to quaternary faulting record in stable continental region scr crust anywhere in the world variation in fault scarp length vertical displacement proximity to other faults and relationship to topography permits division of the continent according to fault character six onshore neotectonic domains are recognised with an additional offshore domain proposed by analogy with the eastern united states each domain relates to a distinct underlying crustal type and architecture broadly considered to represent cratonic non cratonic and extended environments in general greater topographic expression associated with faults occurring in extended crust relative to non extended crust suggests a higher rate of seismic activity in the former setting consistent with observations worldwide using the same reasoning non cratonic crust might be expected to have a higher rate of seismic activity than cratonic crust this distinction together with the variation in fault character between domains should be recognised in attempts to identify analogous systems worldwide a common characteristic of morphogenic earthquake occurrence in australia appears to be temporal clustering periods of earthquake activity comprising a finite number of large events are separated by much longer periods of seismic quiescence at the scale of a single fault and of proximal faults in several instances there is evidence for deformation at scales of several hundred kilometres switching on and off over the last several million years what is not clear from the limited palaeoseismological data available is whether successive active periods are comparable in terms of slip number of events magnitude of events etc regardless this apparent bimodal recurrence behaviour poses challenges for probabilistic seismic hazard assessment psha these rely on the simplifying assumption that large earthquake recurrence for long return periods is not random i e poissonian presently our ability to incorporate such time dependent models is limited by available data

late pleistocene landscape response to climate change eolian and alluvial fan deposition cape liptrap southeastern australia abstract sea cliffs along the western coast of cape liptrap at arch rock provide nearly continuous exposure of calcareous eolianites dated at 68 112 ka five optically stimulated luminescence osl ages calcareous eolian deposition began immediately after the last interglacial marine highstand oxygen isotope stage ois 5e and continued during sea level fall until the beginning of ois 4 west southwesterly winds transported calcareous sand across 12 km of exposed continental shelf by the beginning of ois 4 a brief period of cold arid windy continental climate with ephemeral but intense surface runoff immediately preceded the last glacial maximum lgm this resulted in fluvial reworking of the calcarenites into an alluvial fan dated at 23 25 ka four osl ages the fan overlies peat dated at 25 279 yr cal bp and is capped by a paleosol dated at 6010 yr cal bp concurrent eolian reworking by northwesterly winds of siliceous sediments on marine terraces along the eastern and central portion of cape liptrap formed siliceous longitudinal dunes with ages ranging from 19 to 24 ka five osl ages the phase of maximum landscape instability at cape liptrap coincides with solar insolation and air temperature minima and preceded the lgm by several thousand years

controls on intra plate seismicity in southwestern australia abstract although the southwest seismic zone swsz located about 150 km to the east of perth in southwestern australia is one of the most seismically active areas in australia there is little understanding as to why the earthquakes are occurring an analysis of geophysical geological and geodetic data from the area suggests that the swsz coincides with a precambrian terrane boundary seismic data show that the terrane boundary zone dips at a shallow angle in a northeasterly direction reactivation of this zone of weakness in the contemporary stress field east west maximum horizontal stress is interpreted to be the first order control on seismicity in the region gravity data show that the terrane boundary is offset by near orthogonal structures which are interpreted as faults at least one of these trends corresponds with a linear zone of epicentres the temporal and spatial distributions of epicentres associated with the 1968 meckering earthquake ml 6 9 suggest that the second order distribution of seismicity in the swsz can be explained by the intersection model whereby stresses are amplified by space problems associated with displacements on crosscutting faults it is speculated that a zone of high density and high seismic velocity in the lower crust may also be a second order control on the local seismicity however confirmation awaits better delineation of the extent of this zone

a comparison of 103 105 year uplift rates on the south alkyonides fault central greece holocene climate stability and the formation of coastal notches 1 measurements of holocene coastal notch sequences exposed in the footwall of the active south alkyonides normal fault greece reveal 3 holocene paleoshorelines near the lateral fault tip rising in elevation eastward toward the center of the fault where a 4th paleoshoreline appears the implied eastward increase in holocene uplift rate mirrors that for an uplifted quaternary marine terrace 0 29 mm yr 0 55 mm yr from west to east assuming these uplift rates were constant through the holocene notch elevations predict ages of 650 1900 3700 and 6500 years b p comparable with published 14 c ages on notch fauna and well correlated with periods of relatively stable holocene climate we propose that the notch sequences formed when post glacial sea level rise became outpaced by the coastal uplift rate whilst individual notches formed when stable climate facilitated sustained erosion the parity of the holocene and quaternary uplift rates suggests that notch sequences could be used to characterize long term patterns of uplift slip rate and seismic hazards on active normal faults if 6500 years is long enough to fully characterize temporal variation in the seismic cycle citation cooper f j g p roberts and c j underwood 2007 a comparison of 10 3 1 0 5 year uplift rates on the south alkyonides fault central greece holocene climate stability and the formation of coastal notches geophys res lett 34 l14310

landscape responses to intraplate tectonism quantitative constraints from be 10 nuclide abundances cosmogenic 10 be concentrations in bedrock and alluvium combined with structural studies provide a novel approach for identifying neotectonic forcing of landscape evolution in mildly deforming continental interiors measured 10 be concentrations in the flinders ranges indicate rapid and spatially variable rates of bedrock erosion in a catchment that has incurred at least three large surface rupturing earthquakes since 67 ka 10 be derived erosion rates are lower where late quaternary neotectonic activity is reduced or absent implying that 10 be concentration may act as a tracer for disequilibrium landscapes responding to recent tectonism mechanisms for elevated erosion rates include 1 headward migration of fault generated bedrock knickpoints and resultant oversteepening of stream profiles and catchment hillslopes and 2 liberation of bedrock material from catchment hillslopes via co seismic shaking despite climatic influences on sediment production and transport this study shows that tectonism can provide a dominant control on bedrock erosion rate and relief production in unglaciated mountain belts even in intraplate settings where rates of crustal deformation are mild and earthquake activity is episodic 2007 elsevier b v all rights reserved

modes of active intraplate deformation flinders ranges australia 1 the flinders ranges form one of the most seismically active zones within the australian continent with seismogenic strain rates over the last 30 years of 10 16 s 1 active deformation in the region reflects late neogene increases in stress levels in the indo australian plate as a response to increased plate boundary forcing from collision zones with the neighboring asian and pacific plates geological and geophysical observations suggest two modes of active deformation in operation in the flinders ranges over the last several million years 1 low amplitude 200 500 m long wavelength 200 km lithospheric flexure and 2 active reverse faulting along the range front with fault slip rates of up to 50 m myr 1 numerical models are developed to explore the contribution of each of these deformation modes to the observed geophysical signals an elastic mode of deformation is suggested by a distinctive long wavelength positive correlation between gravity and topography in which the flinders ranges are bordered by anomalous topographic and gravity lows now occupied by playa lake systems centered some 50 km outboard of range bounding faults numerical models show that flexural instabilities localized by vertical loads arising from older tectonic structuring produce a first order match with observed topography and gravity numerical models are also used to illustrate how the localized failure evident in the contemporary seismicity and quaternary faulting record within the flinders ranges reflects thermal weakening associated with extraordinary concentrations of heat producing elements in the crust as reflected in modern day heat flows of 90 mw m 2

the last interglacial shoreline in australia a review abstract marginal marine strata of last interglacial age occur in a range of morphostratigraphic settings around the australian coastline the lithofacies are similar to their holocene equivalents but are partly lithified elevated and laterally displaced inland uranium series ages for corals and molluscs from widely separated localities around the australian coastline are generally in accord with the accepted age for oxygen isotope substage 5e 125 000 10 000 bp the value generally accepted for the last interglacial maximum amino acid racemisation has principally been applied to correlation of sequences with benchmark sites dated by the uranium series method elevations of preserved last interglacial shorelines do not support the notion that australia is a stable continent significant neotectonic anomalies include cape cuvier 10 5 m fleurieu peninsula 6 m the coorong coastal plain 10 m and tasmania 32 m each indicating contrasting degrees of local uplift the tasmanian sequences are the highest occurrence on the australian continent and have been attributed to uplift as a result of mantle hotspot processes with the exception of these tectonically uplifted sites the height of the last interglacial sea surface around the australian coastline is consistently below the 6 m level globally attributed to this high sea level stand in australia the most consistent datum is from western eyre peninsula where a level 2 m above present mean sea level is ubiquitous the more southerly limit of coral growth and wider distribution of subtropical molluscan fauna are in accordance with warmer ocean waters during substage 5e approximately 2 c the extent of racemisation in molluscan fossils from southern australia also excludes the possibility of a more equable latitudinal distribution of mat during substage 5e

scale matters the influence of structural inheritance on fracture patterns abstract fracture systems are often geometrically invariant across a range of scales but the impact of structural inheritance on this relationship is poorly understood this paper shows how fracture orientations in sedimentary rocks vary at different scales when influenced by pre rift basement structures we use high resolution unmanned aerial vehicle uav orthophotos to map folds and fractures in the basement and cover rocks of the gippsland basin southeast australia outcrop scale observations are compared with 1 km long faults previously interpreted from potential field data we use length coloured rose diagrams of fracture traces to compare trends in fracture orientations early cretaceous syn rift normal faults exhibit the same ene wsw trend at basin 1 km and outcrop meters scales pervasive outcrop scale subvertical nnw sse striking joints record a subsequent regional shortening event but at the basin scale this is only expressed as reverse reactivated ene wsw striking faults thus fabrics and or faults in the underlying basement exert significant control on the orientation of basin scale fractures in the cover but appear to have limited influence on outcrop scale fracture orientations our observations show that fracture systems influenced by structural inheritance are not scale invariant and that a proper understanding of structural architecture can only be achieved by analysing data that span multiple scales

evidence for smoothly falling sea level relative to north queensland australia during the past 6 000 yr post glacial sea level curves are expected to differ between different parts of the world as a result of global isostatic changes1 or perhaps other forms of geoidal changes2 i report here results from the inner part of the northern great barrier reef which seem to show a pattern of smoothly falling sea level during the past 6 000 yr the results are consistent with stratigraphical results from prograded mangrove coasts on the nearby north queensland mainland the region is remote from the tectonically active margin of the south west pacific ocean and the results contribute to the global data set relevant to isostatic changes being assembled by the international sea level project igcp project no 61 they also provide a baseline relevant to holocene coral reef growth in the inner great barrier reef

episodic intraplate deformation of stable continental margins evidence from late neogene and quaternary marine terraces cape liptrap southeastern australia the waratah fault is a northeast trending high angle reverse fault in the late paleozoic lachlan fold belt at cape liptrap on the southeastern australian coast it is susceptible to reactivation in the modern intraplate stress field in southeast australia and exhibits late pliocene to late pleistocene reactivation radiocarbon optically stimulated luminescence osl and cosmogenic radionuclide crn dating of marine terraces on cape liptrap are used to constrain rates of displacement across the reactivated waratah fault six marine terraces numbered qt6 tt1 youngest to oldest are well developed at cape liptrap with altitudes ranging from 1 5 m to 170 m amsl respectively on the lowest terrace qt6 barnacles in wave cut notches 1 5 m amsl yielded a radiocarbon age of 6090 5880 cal bp and reflect the local mid holocene sea level highstand qt5 yielded four osl ages from scattered locations around the cape ranging from 80 ka to 130 ka it formed during the last interglacial sea level highstand mis 5e at 125 ka inner edge elevations approximate paleo high tide line for qt5 occur at distinctly different elevations on opposite sides of the waratah fault offsets of the inner edges across the fault range from 1 3 m to 5 1 m with displacement rates ranging from 0 01 mm a to 0 04 mm a the most extensive terrace tt4 yielded four early pleistocene cosmogenic radionuclide crn ages two apparent burial ages of 0 858 ma 0 16 ma and 1 25 ma 0 265 ma and two apparent exposure ages of 1 071 ma 0 071 ma 10be and 0 798 ma 0 066 ma 26al allowing for muonic production effects from insufficient burial depths the depth corrected crn burial ages are 1 8 ma 0 56 ma and 2 52 ma 0 88 ma or late pliocene a late pliocene age is our preferred age offsets of tt4 across the waratah fault range from a minimum of 20 m for terrace surface treads to a maximum of 70 m for terrace bedrock straths calculated displacement rates for tt4 range from 0 01 mm a to 0 04 mm a using a late pliocene age 2 ma identical to the rates calculated for the last interglacial terrace qt5 this indicates that deformation at cape liptrap has been ongoing at similar time averaged rates at least since the late pliocene the upper terraces in the sequence tt3 110 m amsl tt2 140 m and tt1 180 m are undated but most likely correlate to sea level highstands in the neogene terraces tt1 tt4 show an increasing northward tilt with age the waratah fault forms a prominent structural boundary in the lachlan fold belt discernible from airborne magnetic and bouger gravity anomalies seismicity and deformation are episodic episodic movement on the waratah fault may be coincident with sea level highstands since the late pliocene possibly from increased loading and elevated pore pressure within the fault zone this suggests that intervals between major seismic events could be on the order of 100 ka

relative sea levels and coastal sedimentation in southeast australia in the holocene abstract in recent years australian studies of relative sea level change have shown reasonable consistency on the termination date of the postglacial marine transgression at c 6 500 14c years bp the following stillstand period has been characterized in some regions by a slight falling trend from a high stand or in other areas by a level not easily distinguished from the present the latter situation occurs on the embayed coast of new south wales here studies of depositional environments and sequences within bed rock embayments have linked the holocene sea level history to patterns of sedimentation on the inner shelf in bay barriers and in estuaries deposition of quartz rich sand in shoreface flood tidal delta and backbarrier environments occurred during the marine transgre sion and the subsequent stillstand shell fragments from these deposits have been radiocarbon dated shoreline displacement continues to the present day partly in response to changes in availability of sand in the shoreface zone and partly in response to variations in regional storminess patterns a nd the great shroud of the sea rolled on as it rolled five thousand years ago herman melville moby dick

predicted and observed holocene sea levels on the australian coast what do they indicate about hydro isostatic models in far field sites data relating to holocene sea level elevations and ages obtained by radiocarbon dating of relict calcareous skeletons of intertidal organisms from widely spaced parts of the australian coast a far field region of comparative tectonic stability are divisible into two sets namely pre and post ca 3600 yr bp the older ages are from material consistently between 1 5 m and 2 2 m higher than present sea level whereas the younger ages ca 3600 1500 yr bp generally cluster around 1 m above present sea level the elevations do not display any decline in amplitude from north to south over an extensive transect contrary to predictions by hydro isostatic models also there appears to be little difference between time elevation results for the coasts of north queensland new south wales and the bass strait region adjacent to tasmania despite differences in the width of the continental shelf in these three locations and the expectation of some hydro isostatic warping of the continental shelf subsequent to the onset of the holocene transgression results from the south and southwest coasts of western australia also display similar elevations to the east coast for the same time periods there is sufficient evidence extending over 20 of latitude to suggest that north south differences related to hydro isostatic influence is limited or non existent there is insufficient data to test hydro isostatic models across continental shelves hydro isostasy and the lithological elasticity it reflects may not be as pronounced in far field sites with narrow continental shelves as models predict stable far field passive continental margins may be the best place to measure the ratio of inputs of eustatic and hydro isostatic influences on holocene relative sea levels copyright 2002 john wiley sons ltd journal of quaternary science

holocene evolution of the ninety mile beach sand barrier victoria australia the role of sea level sediment supply and climate abstract the ninety mile beach nmb barrier system in southeastern australia is the largest active barrier island system in australia the response of a sandy barrier system to a warming climate is dependent on the boundary conditions of sediment supply and sea level deposition during the holocene can therefore provide an indication of how these barriers may change in the future in this study airborne lidar ground penetrating radar and subsurface coring were combined with 46 optically stimulated luminescence and 32 radiocarbon ages to provide a detailed understanding of sedimentation of nmb through the holocene the barrier complex formed in three distinct phases dating back to the earliest stabilisation of sea level after the postglacial marine transgression first restriction of the flooded open ocean embayment that had formed around a last interglacial beach barrier sequence occurred with accretion of an island complex at around 8000 years bp sourced from transgressive sands reworked from the shelf in the second phase at around 6000 years bp a second barrier island formed seaward of the last interglacial barrier but disconnected from the earlier holocene barrier islands by a large tidal inlet waning sediment supply from the shelf meant that aggradation of these islands slowed by 4000 years bp the third and final phase occurred after 3000 years with the initiation of sediment supply at the southwestern end of the barrier the island system which formed seaward of the last interglacial barrier then prograded by several hundred metres and elongated in a northeasterly direction by tens of kilometres infilling the tidal inlet and enclosing the earliest holocene barrier landward of a newly created lake sediment supply appears to be the primary limiting factor in the development of nmb with indications of a change in wave climate and sea level have an influence on barrier evolution

strontium and sulfur isotope geochemistry of the galeana barite district nuevo leon sulfur and strontium isotope analyses have been used to test the possibility that barite veins in the galeana district of northeastern mexico formed where barium bearing solutions intersected an overlying gypsum bearing unit barite at galeana occurs in essentially monomineralic veins in red beds of the mesozoic age huizachal group at and just below its contact with gypsum of the olvido formation sulfur isotope analyses confirm that the sulfur in the barite delta 34 s 12 3 17 4ppm has the same range as olvido gypsum 13 1 17 6ppm the mean isotopic composition of the barite is about 1 2 per mil heavier than the mean gypsum composition suggesting that fractionation took place during barite deposition strontium isotope compositions of huizachal group rocks fall on an isochron with an age of 227 5 or 3 m y and an initial 87 sr 86 sr ratio of 0 70816 or 0 00004 and the age corrected average huizachal isotopic composition agreed with that of the galeana barites 0 71345 about 30 m y ago consistent with the geologic estimates of the age of mineralization compositions of whole rocks and dilute acid leachates from the huizachal group indicate that the strontium and presumably also the barium were derived from the bulk rock rather than the easily leachable carbonate cement and veinlets the unusually homogeneous isotopic composition of strontium in the galeana barite when compared to data on the scale of strontium isotope heterogeneity in present day formation waters suggests that the galeana mineralization was derived from a relatively small volume of sediment similar to that of a single oil field solubility calculations and data on barium and strontium contents of formation waters indicate that a fluid volume of about 10 11 m 3 would be required if the mineralizing solution contained about 100 ppm barium depending on porosity this volume of water could have come from a 100 to 200 m thickness of huizachal group red beds in the 40 x 20 km structural high underlying the galeana district

warmer or cooler late holocene marine palaeoenvironments interpreting southeast australian and brazilian sea level changes using fixed biological indicators and their δ18o composition abstract relic inter tidal assemblages of sessile organisms which are referred to as fixed biological indicators fbis are shown to be useful proxies for late holocene climatic and environmental changes as well as direct indicators of short term fluctuations in sea level a detailed comparison of change in the inter tidal assemblages of two southern hemisphere sites at comparable latitudes port hacking new south wales south east australia and the laguna imbituba region of southern brazil indicates periods of marked similarities in the timing and nature of changes at 5200 3800 cal years bp and differences after 2400 cal years bp there is sufficient concurrence of cooling phases and falling sea levels to strongly suggest that in some cases global rather than regional forcing factors are at work the value of inter tidal organisms as indicators of changed environments is developed by identifying the past and present distributions of the common marker species tubeworms barnacles and mussels the 18 o content of these extant specimens at port hacking confirmed changes in ocean water temperature and associated sea level behaviour corresponding to invasion or extinction of temperature sensitive species a similar pattern is repeated although in a less marked fashion in the laguna imbituba region of southern brazil

pleistocene coastal stratigraphy sea level highstands and neotectonism of the southern australian passive continental margin a review located in a tectonically stable intraplate setting and in the far field of former ice sheets the southern australian passive continental margin represents a globally important region for quantifying sea level during pleistocene highstands the stratigraphical record of the southern australian margin is dominated by geographically extensive coastal barrier estuarine and peritidal landforms of bioclastic temperate carbonate affinity a function of regional aridity siliciclastic successions dominate the eastern australian coastline despite the generally high level of tectonic stability regional contrasts are evident in the elevation of pleistocene shoreline deposits that largely relate to pre quaternary geotectonic setting the most complete record of pleistocene highstand deposits occurs in the murray basin coorong coastal plain region and indicates that interglacial sea level highstands for at least the past 11 interglacials did not deviate by more than 6 m from present sea level the pleistocene marginal marine record of southern australia is dominantly represented by coastal successions deposited during marine oxygen isotope stages 5e and 7 equating with relative sea level maxima of 2 6 m and greater than 1 m above present sea level apsl respectively intertidal facies of late pleistocene interstadial successions rarely occur above present sea level the most reliable record of glacio eustatic ice equivalent sea level is registered on coastlines developed on stable precambrian cratons such as the gawler craton eyre peninsula where a consistent elevation of 2 m apsl is registered for over 500 km for the last interglacial shoreline 125 ka copyright 2002 john wiley sons ltd

fluvial terraces of the lower susquehanna river abstract fluvial terraces of the lower susquehanna river offer a unique opportunity to investigate the late stage geologic and geomorphic evolution of the u s atlantic passive margin petrography and elevation distinguish and provide a basis for correlation of two groups of terraces the upland terraces and lower terraces through the piedmont newark basin and great valley downstream correlation to dated upper coastal plain and fall zone fluvial deposits relative weathering and soil profile development characteristics establish terrace age upland terraces tg1 tg2 and tg3 middle to late miocene strath terraces 80 to 140 m above the present channel occur only along the piedmont reach they are underlain by unstratified texturally mature quartz dominated roundstone diamictons lower terraces qtg qt1 qt6 pliocene and pleistocene strath and thin aggradational terraces within 45 m of the present channel are underlain by stratified and unstratified texturally and compositionally immature sand gravel and pebbly silt terrace age and longitudinal profiles suggest complex interactions among relative base level long term flexural isostatic processes climate and river grade our model for terrace genesis requires the susquehanna river to attain and maintain a characteristics graded longitudinal profile over graded time for the u s atlantic margin we propose that straths are continually cut along this graded profile during periods of relative base level stability achieved by slow steady isostatic continental uplift acting in concert with eustatic rise change in an external modulating factor such as eustatic fall or climate change results in fluvial incision and subsequent genesis of strath terraces longitudinal profiles of lower susquehanna river terraces which converge at the river mouth diverge through the piedmont and reconverge north of the piedmont contrast with their hypothesized original concave up profiles progressive and cumulative flexural upwarping of the atlantic margin accounts for terrace profile deformation suggesting flexural isostasy as a first order regional deformation mechanism these results offer new interpretations of terrace age correlation and geologic significance that require modification of previous studies suggesting uplifted or anticlinically warped peneplains on the u s atlantic margin

luminescence dating of interglacial coastal depositional systems recent developments and future avenues of research abstract luminescence dating offers new opportunities to explore the evolution of quaternary marine coastal facies and landforms this review highlights the main advances in luminescence geochronology of interglacial coastal sediments through the analysis of 547 luminescence ages most of which were published during the last decade the majority of these reported luminescence investigations have been carried out along passive margin coasts since the turn of the century the discovery of a normalization procedure known as single aliquot regeneration sar has drastically reduced data scatter and improved precision with the consequence that quartz sar optically stimulated luminescence osl has become the dating protocol of choice for the last interglacial lig period a more complex technique known as thermally transferred osl tt osl is presumably proposed for dating older interglacials of the mid pleistocene and beyond feldspar luminescence is increasingly being applied to dating pleistocene sea level high stands due to a much higher dose saturation level than quartz osl the use of feldspar irsl infrared stimulated luminescence is limited by the occurrence of variable but ubiquitous anomalous fading af following the advent of af correction methods several middle pleistocene sites have been amenable to dating albeit with significant related uncertainties recently new protocols involving the measurement of post ir irsl at elevated temperatures have yielded relatively coherent ages for interglacial sediments up to ca 300 ka quartz osl tt osl af corrected irsl and post ir irsl ages are generally correlated with periods of sea level high stands a few ages are reported from the early and middle part of the middle pleistocene as mis11 9 and more commonly mis7 high stands are documented in strongly uplifting active margin coasts however by far the most obvious age peak corresponds to the end of the lig the mis5e shoreline is probably the most studied and luminescence dated coastal feature of all as the chronology of the sea level markers is crucial to assess global eustatic sea level variations through the course of the last interglacial nevertheless the observed abundance of young 100 120 ka luminescence ages for presumed mis5e sediments may underline methodological issues and or reflect the higher preservation potential of late regressive sequences on the other hand the occurrence of geographically distant reports of mis5a high stand might reflect a true eustatic origin for this event age analysis supports the impression of general reliability of luminescence for the timing of former sea level high stands there is a clear need to address issues in dose rate variability in the phenomenology of fading in feldspar and in the behaviour of luminescence growth with dose both in laboratory and natural conditions these could be addressed and properly evaluated by dating different minerals as multiple or single grains with consequent variable internal dose rates more robust practices in the application of luminescence dating techniques could eventually constrain the age uncertainties to no better than 2 3 therefore the strength of luminescence as a dating tool is more in terms of its extended age range and the ubiquity of datable material

correlation of east australian pleistocene shorelines with deep sea core stages a basis for a coastal chronology a review of recent attempts to relate emerged shorelines to deep sea core stages indicates that correlations based on radiometric ages must be treated carefully for stratigraphic control is often lacking radiometric ages help field interpretation but some authors question the geology before questioning the dates the view that oxygen isotope values in deep sea sediment cores reflect changes in ocean volume is used to interpret sequences of stranded shorelines in gippsland victoria southeast queensland new zealand south carolina united states and morocco as a basis for study it is accepted that all of the shorelines in the areas compared result from global changes of sea level superimposed on continuously emerging land masses that have been rising uniformly but at different rates in the different localities five stands of the sea ending at the last interglacial maximum are recognized and correlated with dated deep sea core stages as follows g11 gippsland woorim queensland awatuna 1 new zealand silver bluff south carolina ouljian morocco core substage 5e 125 000 yr g26 bribie qld karoro nz princess anne harounian core stage 7 220 000 yr g37 poyungan qld albion 113 nz pamlico anfatian g2 stage 9 330 000 yr g65 ungowa qld albion 165 nz bethera stage 11 430 000 yr g70 albion 183 nz talbot anfatian thomas quarry stage 13 480 000 yr implied rates of uplift are used to date and correlate six earlier shorelines g125 penholoway late maarifian 1 02 m y g160 wicomico maarifian 1 18 m y g260 okefenokee haj salah 1 43 m y g360 sunderland sidi messaoud 1 64 m y g420 coharie bouchaib bel kamel 1 80 m y a600 orange burg fouaratian 2 35 m y

mapping folds and fractures in basement and cover rocks using uav photogrammetry cape liptrap and cape paterson victoria australia abstract brittle and ductile deformation of alternating layers of devonian sandstone and mudstone at cape liptrap victoria australia resulted in upright folds with associated fold accommodation faults and multiple fracture sets structures were mapped at the fold stack locality at cape liptrap using high resolution aerial photographs acquired by a digital camera mounted on an unmanned aerial vehicle uav subsequent photogrammetric modelling resulted in georeferenced spatial datasets point cloud digital elevation model and orthophotograph with sub cm resolution and cm accuracy which were used to extract brittle and ductile structure orientation data an extensive dataset of bedding measurements derived from the dense point cloud was used to compute a 3d implicit structural trend model to visualise along strike changes of devonian tabberabberan folds at the fold stack locality and to estimate bulk shortening strain this model and newly collected data indicate that first generation shallowly south southwest plunging upright folds were gently refolded about a steeply plunging subvertical fold axis during a devonian low strain north south shortening event this also led to the local tightening of first generation folds and possibly strike slip movement along regional scale faults in order to distinguish fractures associated with devonian compression from those that formed during cretaceous extension and later inversion we compared the five fracture sets defined at cape liptrap to previously mapped joints and faults within the overlying sedimentary cover rocks of the cretaceous strzelecki group gippsland basin which crop out nearby an east southeast trending fracture set that is not evident in the strzelecki group can be linked to the formation of devonian folds additionally hinge line traces extracted from the fold stack dataset are aligned parallel to a dominant fracture set within the overlying cover sediments this suggests that basement structures folds and coeval parallel faults have an important influence on fault and joint orientations within cretaceous cover rocks

the mendocino triple junction active faults episodic coastal emergence and rapid uplift a complex zone of rapid holocene surface uplift and deformation occurs at the mendocino triple junction the juncture of three plate bounding faults the cascadia subduction zone san andreas fault and mendocino fault within this mountainous structural knot up to 1 4 m of coastal emergence occurred during the 1992 cape mendocino m s 7 1 earthquake surveying and radiometric dating of ancient marine strandlines 7 5 along the cascadia subduction zone megathrust however another plausible interpretation of the data is that multiple earthquakes resulting in smaller amounts of net surface uplift per event similar to the 1992 earthquake occurred closely spaced in time giving the appearance in the geologic record of less frequent and larger events regardless of the number and timing of paleoearthquakes the number of platforms is a minimum of the number of events that resulted in sudden rapid uplift because platform preservation is also a function of rising holocene sea level at present rates and patterns of net surface uplift are better constrained than the timing and magnitude of paleoearthquakes periods of rapid holocene emergence also are identified as far south of the area of 1992 uplift and the mendocino fault as 30 km along the unlocated san andreas fault these also might be associated with coseismic uplift based on new mapping of active faults in the region it is proposed here that this uplift is the result of multiple discontinuous thrust and strike slip fault segments which distribute plate boundary deformation along a restraining bend at the termination of the san andreas fault this interpretation is consistent with the fact that a single prominent strike slip fault has not been identified in the mendocino triple junction region while several small reverse faults crossing holocene deposits and geomorphic surfaces have been mapped and dated

tectonic geomorphology of australia the australian continent is actively deforming in response to far field stresses generated by plate boundary interactions and buoyancy forces associated with mantle dynamics on the largest scale several 10 3 km the submergence of the northern continental shelf is driven by dynamic topography caused by mantle downwelling along the indo pacific subduction system and accentuated by a regionally elevated geoid the emergence of the southern shelf is attributed to the progressive movement of australia away from a dynamic topography low on the intermediate scale several 10 2 km low amplitude c 100 200 m long wavelength c 100 300 km topographic undulations are driven by 1 anomalous smaller scale upper mantle convection and or 2 lithospheric scale buckling associated with plate boundary tectonic forcing on the smallest scale 10 1 km fault related deformation driven by partitioning of far field stresses has modified surface topography at rates of up to c 170 m ma 21 generated more than 30 50 of the contemporary topographic relief between some of australia s highlands and adjacent piedmonts and exerted a first order control on long term 10 4 10 6 a bedrock erosion although australia is often regarded as tectonically and geomorphologically quiescent neogene to recent tectonically induced landscape evolution has occurred across the continent with geomor phological expressions ranging from mild to dramatic australia is one of the lowest flattest most arid and most slowly eroding continents on earth the average elevation of the continent is only c 330 m above sea level asl maximum local topographic relief is everywhere 1500 m defined by elevation ranges with 100 km radii and two thirds of the con tinent is semi arid to arid with the exception of localized upland areas in the flinders and mt lofty ranges and the eastern highlands bedrock

facies sequence of triassic jurassic red beds in the sierra madre oriental ne mexico and its relation to the early opening of the gulf of mexico abstract the configuration of upper triassic grabens in the gulf of mexico rift system is pointed out by the suture zones of late palaeozoic plate convergence rifting particularly started on both sides of the ancient magmatic arc the taphrogenic red beds of the huizachal formation in the sierra madre oriental represent the western parts of this system the early syn rift sediments are characterized by fining upward cycles of a fluvial environment with a low sinuosity channel pattern later on decreasing of relief intensity caused the change to a rather meandering system climate was evidently semiarid during that time the petrographic composition of the clastic rocks suggests a nearby sedimentary metamorphic basement the transition to early post rift sediments is marked by an angular unconformity its formation approximately coincides with the first emplacement of oceanic crust in the central parts of the gulf basin the early post rift sediments of the la joya formation show within a single fining upward megacycle the transition from terrestrial to marine conditions that persisted up to the beginning of cenozoic time

marine notches in coastal cliffs indicators of relative sea level change perachora peninsula central greece abstract in several sites in the complex faulted western part of perachora peninsula central greece three principal marine notches in rocky coasts are present in each site no holocene notches occur above the upper of the three notches only subaerial weathering affected the rocks lateral variation in the heights of notches demonstrates differential uplift due to fault control and illustrates the complexity of application of marine notches in interpretation of tectonic history the lower undated notch is prominent in places coincides with modern sea level and is interpreted to be forming now it suggests that the western part of the peninsula has been stable for a considerable time the middle and upper notches vary in height between sites and may not be time equivalent but represent earlier sea level positions in the harbour adjacent to the heraion archaeological site the middle and upper notches are preserved in most places as notch roofs so that gradual uplift led to removal of notch floors by physical chemical and biotic processes in exposed locations however within a few hundred metres west of the harbour four uplifted plus a fifth forming now notches have been illustrated by pirazzoli et al tectonophysics 229 1994 201 that cannot be readily correlated to the harbour site and indicate differential uplift by fault displacement in a more complex situation at mylokopi 6 km ne of heraion three different notch profiles occur in three blocks separated by two faults however within the central block of the three two very different profiles are preserved only tens of metres apart beneath one continuous upper notch roof at the same height this complex arrangement interpreted as variability of exposure to marine processes on different parts of this irregular embayment such that one profile containing three notches was controlled largely by abrasion and formed notches that are vertically more extensive while the other profile containing five narrow notches formed by dissolution and or biological erosion at the same time in the protected east end of the block however if only one or the other profile was visible very different tectonic interpretations would result the bedrock of perachora peninsula also shows important variations in resistance to erosion affecting the resulting notch profiles and some sites are influenced by structurally controlled differential subaerial weathering forming ridges and grooves giving the false impression of extra minor notches the distinction between dissolution controlled and structure controlled minor notches may not be possible in some places the interpretations of notch profiles can be highly complex and influence views of tectonic history in a given region overall the occurrence of three principal notches beneath one uplifted notch roof in several sites indicates that a holocene uplift rates outpaced post glacial sea level rise b there were three principal periods of relative sea level stillstand affecting the perachora peninsula and c uplift of the entire western part of the perachora peninsula is an important component of its tectonic processes probably more important than fault movement within the peninsula

use of a new 10be and 26al inventory method to date marine terraces santa cruz california usa marine terraces along active continental margins reflect the interplay between sea level oscillations and rock uplift well dated marine terraces record the timing of sea level highstands and delimit both uplift and geomorphic rates cosmogenic radionuclides provide a new tool for dating previously undatable terraces because the five marine terraces north of santa cruz california are capped by well developed soils formed in regressive marine sands both predepositional cosmogenic radionuclide inheritance and bioturbation of the profile must be accounted for we present a new cosmogenic radionuclide inventory method that uses the depth integrated cosmogenic radionuclide concentration to determine the terrace age this method yields terrace ages that correlate well with sea level highstands of marine oxygen isotope stages 3 5a 5c 5e and 7 the implied uplift rate is steady at 1 1 mm yr and is two to three times higher than rates suggested by earlier studies

timing and duration of the last interglacial evidence for a restricted interval of widespread coral reef growth abstract we report new mass spectrometric u series ages for eight last interglacial fossil reefs along the continental margin of western australia corals were selected in growth position from localities that are characterized by apparently low levels of diagenesis and relative tectonic stability so that the fossil reefs provide critical information on last interglacial sea levels without requiring corrections for tectonic movements in addition we have improved the constraint on the timing of onset of reef growth by recovering drill core coral from the base of the reefs uranium and thorium isotopes were measured with high levels of precision leading to improvements in age resolution and allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified and discarded these data supplement our previous results for rottnest island and leander point leading to more than seventy mass spectrometric u series ages from which constraints can be placed on the timing duration and character of the last interglacial sea level highstand reliable ages show that reef growth started contemporaneously at 128 1 ka along the entire western australian coastline while relative sea levels were at least 3 m above the present level because western australia is located far from the former penultimate glacial maximum ice sheets and are not significantly effected by glacial unloading these data constrain the timing of onset of the last interglacial period to 128 1 ka assuming reef growth started soon after sea level approached interglacial levels a unique regressive reef sequence at mangrove bay constrains the timing of termination of the last interglacial period to 116 1 ka the major episode of reef building however both globally and locally along the western australian coast is restricted to a very narrow interval occurring from 128 ka and 121 ka suggesting that global ocean surface temperatures were warm and or sea levels were stable enough to allow prolific reef growth only during the earlier part of the last interglacial

quaternary shorelines in southern peru a record of global sea level fluctuations and tectonic uplift in chala bay abstract the coastal area bordering the bay of chala 14 50 s 74 15 w southern peru contains one of the most complete sequences of quaternary shorelines in south america remnants of about 27 high seastands have been preserved between present mean sea level and 275 m most remnants consist of staircased marine terraces and associated deposits which are partly covered by alluvial fan and colluvial units deposited during intervening periods of lower sea levels no geochronological data are yet available a tentative chronostratigraphy of the terrace sequence is based on the geometric and stratigraphic relationships between successive landforms and deposits we group most marine terraces into 15 major morphostratigraphic units mmus some of these major units seem to correlate with interglaciations for example isotopic stage 5 or with interstadials stage 3 higher in the chala sequence major morphostratigraphic units mapped during field and air photo studies may represent only parts of middle pleistocene interglaciations we infer that shorelines located at 68 121 168 and 184 or 200 m correlate with the highest seastands of isotopic stages 5 7 9 and 11 respectively the proposed chronostratigraphy suggests an average uplift rate of ca 460 mm kyr for the chala bay area during the last 500 ka this rate is slightly higher than in the surrounding coastal areas ca 270 350 mm kyr but significantly lower than rates in the area where the nazca ridge is being subducted below the south american plate maximum rate ca 740 mm kyr deformed shorelines evidence several fault displacements within the chala basin but such deformation does not seriously disort the record of former sea levels in the basin the chala terrace sequence is the first reliable record of middle and late quaternary sea level fluctuations described from peru

chronology of the marine terraces of the crotone peninsula calabria southern italy by means of infrared stimulated luminescence irsl abstract the crotone peninsula southern italy preserves a well developed flight of marine terraces generated by the interplay of uplift of the calabrian arc and late quaternary eustatic oscillations good chronologic control on the formation of these raised geomorphic features would help constrain regional tectonic and stratigraphic models however precise age assignment and correlation of the individual terraces is hampered by lack of material suitable for radiometric dating with the goal of improving the resolution of the chronology of the terraces nine samples were collected from four stratigraphically distinct terraced units and dated with the infrared stimulated luminescence irsl technique applied on feldspar grains the obtained ages are consistent with the stratigraphic arrangement of the terraces with samples from higher terraces older or overlapping in age with those from lower terraces three samples from the highest cutro terrace indicated a minimum age mis marine isotope stage 7 two samples from the second of the four examined terraces which is generally correlated with mis 5 3 gave ages that correlate instead with mis 5 5 and 5 1 revealing more internal complexity and tectonic disruption than previously inferred from this terrace luminescence dating was applied for the first time to the deposits of the capo colonna terrace with results indicating a mis 5 1 age finally one sample from the lowermost le castella terrace confirmed the preservation of raised marine deposits from mis 3 a relatively uncommon finding for the mediterranean region these results highlight how irsl dating can contribute to the development and refinement of a chronostratigraphic context for a flight of marine terraces and ultimately to a clearer understanding of the combined tectonic and eustatic controls affecting the morphodynamic evolution of a marine coastal sector more specifically they confirm the persistence of relatively high average uplift rates on the order of 1 mm yr over the last two glacial cycles in the crotone peninsula and the important role of a local component of tectonic and deformative displacement superimposed on the regional uplift

volcanogenic origin of cenotes near mt gambier southeastern australia abstract the cenotes near mt gambier are circular cliffed collapse dolines containing water table lakes up to 125 m deep floored by large rubble cones they lie in a flat coastal plain composed of mid tertiary limestone most of the deepest cenotes are concentrated in two small areas located along trends sub parallel to the main joint direction in the limestone the cenotes do not connect to underwater phreatic passages and water chemistry data confirm that they are not part of an interconnected karst network they formed by collapse into large chambers up to 1 million m 3 that extended 125 m or more below the land surface several cenotes have actively growing stromatolites on the sub vertical walls that started growing at 8000 years bp the caves that collapsed to form the deep mt gambier cenotes are much larger than shallow and deep phreatic caves in the area and do not connect into deep phreatic systems they were not formed by freshwater seawater mixing responsible for many of the well known yucatan cenotes because they are not associated with locations of the mixing zone during previous high sea levels and are much larger than caves presently forming along the mixing zone near mt gambier instead dissolution was most likely due to a process whereby acidified groundwater containing large amounts of volcanogenic co 2 ascended up fractures from the magma chambers that fed the pleistocene holocene volcanic eruptions in the area deep reservoirs of volcanogenic co 2 occur nearby cave dissolution could have been due to release of co 2 during the mt gambier eruption 28 000 years ago followed by collapse to form cenotes during the low sea levels of the last glacial maximum 20 000 years ago the cenotes then flooded 8000 years ago as sea level rose and stromatolites began to grow on the walls

high eustatic sea level during the middle pliocene evidence from the southeastern u s atlantic coastal plain the middle pliocene approximately 3 5 2 5 ma was a period of global warmth preceding the growth of major northern hemisphere ice sheets the authors report on eustatic sea level for the middle pliocene based on microspaleontologic study of marine deposits of the duplin formation of south carolina and north carolina the duplin was deposited during a middle pliocene marine transgression that formed the orangeburg scarp a prominent wave cut geomorphic paleoshoreline of the southeastern u s atlantic coastal plain they concluded that 1 the scarp in south carolina was formed mostly during the middle pliocene 3 5 3 0 ma 2 eustatic sea level was about 35 plus minus 18 m higher than modern sea level the scarp has been uplifted about 50 65 m since the middle pliocene and 3 ocean water temperatures along eastern north america were warmer when the scarp was formed that they are at present

long term and short term global cenozoic sea level estimates backstripping analysis of three continuously cored well dated boreholes from the new jersey coastal plain ocean drilling program odp leg 150x indicates a long term 10 8 n10 7 yr eustatic fall of 100 m since 55 ma early eocene and suggests short term 0 5n3 m y eustatic falls of less than 70 m eustatic estimates are calculated from residuals between the decompacted unloaded and paleodepth corrected records and tectonic subsidence assuming a cooling lithospheric plate because the residuals are similar among the three sites we interpret them as an approximation of the eustatic signal

topography boundary forces and the indo australian intraplate stress field the relative contribution of topographic e g ridge push continental margins and elevated continental crust and plate boundary e g subduction and collisional forces to the intraplate stress field in the indo australian plate iap is evaluated through a finite element analysis two important aspects of the iap intraplate stress field are highlighted in the present study 1 if substantial focusing of the ridge push torque occurs along the collisional boundaries i e himalaya new guinea and new zealand many of the first order features of the observed stress field can be explained without appealing to either subduction or basal drag forces and 2 it is possible to fit the observed shmax maximum horizontal stress orientation and stress regime information with a set of boundary conditions that results in low tectonic stress magnitudes e g tens of megapascals averaged over the thickness of the lithosphere throughout the plate this study therefore presents a plausible alternative to previous studies of the iap intraplate stress field which predicted very large tectonic stress magnitudes hundreds of megapascals in some parts of the plate in addition topographic forces due to continental margins and elevated continental material were found to play an important role in the predicted stress fields of continental india and australia and the inclusion of these forces in the modeling produced a significant improvement in the fit of the predicted intraplate stresses to the available observed stress information in these continental regions a central focus of this study is the relative importance of the boundary conditions used to represent forces acting along the northern plate margin we note that a wide range of boundary conditions can be configured to match the large portion of the observed intraplate stress field and this nonuniqueness continues to make modeling the iap stress field problematic while our study is an important step forward in understanding the sources of the iap intraplate stress field a more complete understanding awaits a better understanding of the relative magnitude of the boundary forces acting along the northern plate margin

spatial and temporal variability in the holocene sea level record of the south australian coastline abstract studies of past sea levels based on radiocarbon dated field samples suffer variously from compilation of information from disparate locations and the imprecise nature of the dated indicators geographic segregation and systematic elimination of poor samples from time depth data sets leads to improved interpretation of holocene sea level history an example is presented from southern australia where this is achieved through selection of higher resolution palaeoenvironmental indicators separation of transgressive from regressive populations and geographic regionalisation of data in southern australia fossil sea level indicators preserved in prograding coastal plain settings include seagrass sandflat mangrove samphire and chenier ridge organo sedimentary remains these provide sea level time depth data points with a variety of elevational and dating errors preserved organic remains at the transition from posidonia seagrass to intertidal sandflat environment and from sandflat to avicennia mangrove environment provide the most precise local data for tracing sea level change time depth plots of 233 dated sea level indicators from south australia generate a broad sea level envelope tracing the southern australian transgression from 10 000 to ca 6000 radiocarbon years bp followed by a more or less consistent level to the present finer details of sea level behaviour are only apparent after systematic selection separation and regionalisation of the data the data indicate a very rapid sea level rise in the early holocene at about 16 mm year reaching present levels at 6400 years bp this was followed by regionally variable regression and emergence of the land of 1 3 m a process that continues to the present the systematic increase from 1 to 3 m in the elevation of the 6400 year bp highstand with distance away from the shelf margin is consistent with a hydro isostatic origin for the emergence as predicted by geophysical models

mountain building along a passive margin late neogene tectonism in southeastern victoria australia the hoddle ranges maximum elevation of 750 m above sea level lie along the southeastern australian passive margin detailed geological geomorphological studies of the southern margin of the ranges focusing on a fault block of oligocene miocene sedimentary rocks have constrained the landscape evolution in the mid cretaceous this area changed from a subduction zone accumulating volcanogenic sediments to a passive low relief margin which was crossed by north flowing rivers in the paleocene the eruption of basaltic volcanics formed a low divide which diverted these rivers towards the northeast so that sediments deposited on either side of the divide contain different heavy mineral assemblages in the middle late miocene early pliocene the area was subjected to a period of relatively rapid mountain building the kosciuszko uplift as broadly nw se oriented compression created the hoddle ranges at an uplift rate of 0 15 mm a uplift was not uniform a small southern block was uplifted only 200 m and its surface has acted as a local base level for the agnes river which flows across it with a major knickpoint on the southern side the southeastern highlands to the north were uplifted by up to 700 1000 m during the kosciuszko uplift similar to the maximum increase in elevation of the hoddle ranges 600 m the kosciuszko uplift tectonism occurred at rates greater than typical of passive margins and belies australia s reputation as a tectonically stable continent

strontium and sulphur isotope geochemistry of low temperature barite fluorite veins of the catalonian coastal ranges ne spain a fluid mixing model and age constraints sulphur and strontium isotope analyses from the low temperature barite fluorite veins of the catalonian coastal ranges ne spain reveal the nature and source of the ore forming fluids and constrain the ages of the mineralizations sulphur isotope values in the barite 34s 15 to 20 are similar to those of sulphates in nearly triassic jurassic evaporites 34s 11 to 19 87sr86sr isotopic composition ratios of barites and fluorites are 0 7094 0 7167 the variation of 87sr86sr within individual veins suggests that the sr had two different sources granites rocks in the hercynian basement and seawater or evaporites of triassic early jurassic age vein formation is modelled as a two component mixing process in which the s and sr isotopic composition of the end members change with time the observed difference in mean s and sr isotopic compositions among the veins is interpreted to reflect differences in mineralization age ore deposition occurred between 225 and 195 ma triassic to early jurassic in all cases except the berta mine which may be as young as miocene

summer upwelling and thermal fronts in the northwestern south china sea observational analysis of two mesoscale mapping surveys persistent coastal upwelling and upwelling induced thermal fronts in the northwestern south china sea are investigated using satellite measurements two intensive mesoscale mapping surveys and three bottom mounted adcps the results indicate that pronounced surface cooling and upwelling related fronts with a width of 20 50 km occur around hainan island and persist through the summer upwelling season driven by the prevailing southwesterly monsoon the subsurface cooling band is approximate to 6 degrees c colder than the water offshore of the east coast where the thermal gradients are generally more than 0 1 degrees c km the cold and nutrient rich coastal water is identified to be derived primarily from the deep water of the outer shelf at the same time the spatial structure of the upwelling and thermal front as well as the upwelling related coastal currents is significantly regulated by wind forcing a prominent lagged correlation between the moored temperature records and alongshore wind stress is detected in the east coast the correlation coefficient is 0 8 with the temperature lagging behind wind stress by 2 2 days indicating that the cooling band off the east coast is dominated mostly by the alongshore southwesterly monsoon during the upwelling season

luminescence and radiocarbon chronologies of playa sedimentation in the murray basin southeastern australia abstract playa lakes are important palaeoenvironmental repositories in arid landscapes as geochemically open and organically poor systems however accurate dating of playa sequences is often hampered this study paired accelerator mass spectrometry radiocarbon ams 14c and optically stimulated luminescence osl ages from four murray basin playa lakes to assess the accuracy of the chronometric techniques in these environments the osl dating directed the sampling strategy which targeted sandier sections of the playa lacustrine sequences these appear to comprise aeolian derived fine quartzose sand ensuring the effective resetting of the luminescence signals prior to deposition in contrast the 14c ages were on bulk organic carbon and not targeted ages are generally in stratigraphic order and span the middle late last glacial and holocene this accords with models of past groundwater hydrology for the playa basins only half of the paired samples are in agreement at 2 precision however with five of the 14c ages older than their corresponding osl ages low organic contents of playa sediments increases the susceptibility of 14c ages to contamination with the incorporation of small amounts of dead carbon into the dated samples possibly accounting for the apparent discrepancies obtaining valid chronologies from arid settings requires close targeting of dated fractions the application of independent techniques is essential for scrutinizing the dating results

evidence for the timing and duration of the last interglacial period from high precision uranium series ages of corals on tectonically stable coastlines the last interglacial period has a timing and duration that can be estimated from u series dating of emergent coral bearing deposits on tectonically stable coastlines high precision dating from bermuda the bahamas hawaii and australia suggests that the last interglacial period had a sea level at least as high as present from 128 000 to 116 000 yr b p sea level reached a near present level more quickly after the close of the penultimate glacial period than at the close of the last glacial period and the duration of high sea level is longer than that implied by the deep sea record c 2002 university of washington

paleoseismicity of two historically quiescent faults in australia implications for fault behavior in stable continental regions paleoseismic studies of two historically aseismic quaternary faults in australia confirm that cratonic faults in stable continental regions scr typically have a long term behavior characterized by episodes of activity separated by quiescent intervals of at least 10 000 and commonly 100 000 years or more studies of the approximately 30 km long roopena fault in south australia and the approximately 30 km long hyden fault in western australia document multiple quaternary surface faulting events that are unevenly spaced in time the episodic clustering of events on cratonic scr faults may be related to temporal fluctuations of fault zone fluid pore pressures in a volume of strained crust the long term slip rate on cratonic scr faults is extremely low so the geomorphic expression of many cratonic scr faults is subtle and scarps may be difficult to detect because they are poorly preserved both the roopena and hyden faults are in areas of limited or no significant seismicity these and other faults that we have studied indicate that many potentially hazardous scr faults cannot be recognized solely on the basis of instrumental data or historical earthquakes although cratonic scr faults may appear to be nonhazardous because they have been historically aseismic those that are favorably oriented for movement in the current stress field can and have produced unexpected damaging earthquakes paleoseismic studies of modern and prehistoric scr faulting events provide the basis for understanding of the long term behavior of these faults and ultimately contribute to better seismic hazard assessments

dating sediment burial with in situ produced cosmogenic nuclides theory techniques and limitations abstract dating sediment burial over million year time scales is crucial in many areas of the earth sciences and archeology but is often difficult using traditional techniques sediment burial can be dated by the radioactive decay of cosmogenic nuclides provided that the sediment was exposed to cosmic rays prior to burial dating calculations are straightforward if sediment is buried deeply and rapidly enough to prevent cosmogenic nuclide production after burial however the analysis can be complicated by postburial production if sediment is insufficiently shielded from secondary cosmic ray nucleons and muons this paper discusses how buried sediments can be dated over timescales up to 5 myr using 26 al and 10 be in quartz

cause and evolution of intraplate orogeny in australia abstractintraplate orogeny remains an enigmatic process in terms of plate tectonics regional continental stress elds agree well with stress orientations predicted by the main forces driv ing and resisting plate motion however regional continental stress elds fail to explain major localized compressive plate deformation in continental interiors far away from plate bound aries global or plate wide intraplate stress models typically assume a laterally homogeneous plate rheology and are con ned to modeling the present without addressing the antiquity of the current stress eld an understanding of intraplate stress and deformation requires the linking of spatial variations in continental rheology with time dependent plate geometry and driving forces here we demonstrate how the complex interplay between juxtaposed weak and strong geological provinces and changes in far eld plate boundary forces has caused intra plate orogenesis and tectonic reactivation in southeastern australia during the tertiary our ndings are contrary to the opinion that continental interiors are insensitive to compression at plate margins and help to explain the mechanisms causing intraplate orogenesis keywords

holocene forearc block rotation in response to seamount subduction southeastern peninsula de nicoya costa rica the southeastern tip of the peninsula de nicoya costa rica on the caribbean plate margin lies inboard of the rough bathy metric terrain on the subducting cocos plate and along the land ward projection of the convergence vector for the fisher seamount group the southern tip of the peninsula has nearly orthogonal coastlines and extensive well preserved holocene marine terraces

the origins of the intraplate stress field in continental australia the ridge push force acting on the indo australian plate exerts a significant torque 8 5 1025n m about a pole at 30 3 n 34 5 e the angular difference between this torque pole and the observed pole of rotation for the plate 19 2 n 35 6 e is less than 12 and suggests that the ridge push force plays an important role in the dynamics of the indo australian plate we have used an elastic finite element analysis to study the predicted intraplate stress field in continental australia for four models which employ different boundary conditions to balance the ridge push torque acting on the plate the modeling indicates that a number of important features of the observed stress field within the australian continent can be explained in terms of balancing the ridge push torque with resistance imposed along the himalaya papua new guinea and new zealand collisional boundaries segments these features include n s to ne sw oriented compression in the northern australia and e w oriented compression in southern australia our analysis also shows that subduction processes along the northern and eastern boundaries provide only second order controls on the intraplate stress field in continental australia

new evidence for the holocene sea level high from the inner shelf central great barrier reef australia radiocarbon dates from fossil oyster beds of intertidal origin on magnetic island north queensland indicate that the local holocene maximum of relative sea level was attained no later than 5660 50 b p conventional uncorrected age and remained at 1 6 1 7 m above modern levels until 4040 50 b p given the tectonic stability of the area this implies that eustatic sea level remained at its holocene peak for at least ca 1600 yr the new high precision sea level data indicate sea levels 1 5 m higher than those of the same age inferred from buried mangrove deposits on the inner shelf in north queensland uncertainties in deriving relative sea level from such mangrove deposits may be a significant source of error in worldwide attempts to distinguish the eustatic and crustal warping components off relative sea level change especially in the tropics

enhanced intraplate seismicity along continental margins some causes and consequences abstract in australia much of the seismic activity is restricted to zones up to several hundred kilometres wide inboard of continental margins at high angle to the trend in maximum horizontal compression shmax intriguingly along the margin side of one such zone a near optimally oriented crustal scale structure the darling fault has no recorded historical seismicity to explain these enigmatic features we explore how the compositional and thermal structuring of continental passive margins may lead to variations in mechanical response to imposed forcing using forward modelling we show how lateral heat flow across such margins can produce increases in moho temperatures by several 10s of degrees relative to the continental interior extending up to 200 km inboard of the ocean continent transition provided the step in thermal lithosphere thickness into the continent is greater than 30 km for smaller lithospheric steps moho temperatures beneath continental margins will be cooler than beneath interiors our mechanical models show that such thermal effects can elevate strain rates along the margin by several factors relative to continental interiors when subject to far field forcing in the shallow seismogenic realm the strain rate maximum is concentrated at around 100 150 km inboard of the ocean to continent lithospheric step providing a plausible explanation for the pattern of seismicity observed in some of australia s marginal seismic zones this interpretation requires that strength changes associated with moho temperature variations of several 10s of degrees are sufficient to override the reactivation potential of near optimally oriented crustal penetrative structures with thermal processes providing an important switch controlling reactivation potential of existing structures it also provides an insight into the mechanism of formation of continental ribbons during rifting of thermally mature margins