charriage crustal anatexie et decrochements ductiles dans les maures orientales var france au cours de l orogenese varisque la cinematique et la signification tectonique des deformations enregistrees par les gneiss catazonaux des maures orientales socle varisque de provence france sont precisees les evenements successifs peuvent etre correles avec les evolutions metamorphiques et magmatiques l histoire orogenique des maures orientales apparait composee des evenements suivants 1 metamorphisme a haute pression uniquement conserve dans des reliques d eclogite et de quartzite a silicates calciques 2 metamorphisme catazonal accompagne d anatexie contemporain d un transport subhorizontal vers le nne d echelle crustale cet episode est responsable de la dilaceration des unites lithologiques de leur laminage et de leur mylonitisation 3 intrusion d une premiere generation de granitoides anatectiques 4 deuxieme episode tectonique dans des conditions epi a mesozonales responsable du deplacement vers le nord des maures orientales par rapport aux maures occidentales le long d un decrochement senestre de 4 km d epaisseur faille de ramatuelle plan de la tour dans lequel les granitoides d anatexie precoces sont mylonitises en dehors de la zone de faille cet episode est marque par des plis ouverts droits ou deverses vers l ouest orientes n s parallelement a la direction de transport 5 reactivation cataclastique moderee de la faille de ramatuelle plan de la tour avec un mouvement dextre localement accompagne dans la partie est de la region par des chevauchements mineurs vers le sud 6 intrusion d une deuxieme generation de granites anatectiques vers 320 ma

sedimentology and hydrocarbon potential of yager structural complex possible paleogene source rocks in eel river basin northern california the yager structural complex of coastal northern california is composed of paleogene mudrocks turbidites and related deep marine deposits the strata are folded but lack the severe and pervasive stratal disruption that characterizes surrounding accreted terranes such as the franciscan coastal belt lithofacies associations and depositional cycles define three environmental settings slope feeder channel and restricted basin the rocks probably represent a sequence of trench slope and slope basin deposits that accumulated above a broadly coeval basement of accreted coastal belt rocks yager strata are possible source beds for hydrocarbons within the late cenozoic eel river basin type iii kerogen is dominant and organic carbon content and hydrocarbon yield are relatively low nevertheless the thermal maturity of yager shales is well within the window of peak hydrocarbon generation this level of maturation is attributed to a combination of middle tertiary thrust faulting and subsequent depositional burial beneath the neogene wildcat group

fission track analysis reveals character of collisional tectonics in new zealand during the late cenozoic the pacific plate has been obliquely converging with the australia plate in south island new zealand this has resulted in westward obduction of continental crust of the pacific plate and consequently a major mountain range the southern alps has formed east of the alpine fault and within the leading edge of the pacific plate we have applied the apatite and zircon fission track dating technique to a suite of outcrop samples from three transects across the southern alps starting at the alpine fault to better understand the uplift age and structure of the continental collision the results show the following 1 uplift was underway at 7 ma in the south at haast pass and by 5 ma in the north at arthur s pass 2 profiles of the total amount of late cenozoic uplift show an exponential increase toward the alpine fault adjacent to the alpine fault there has been 14 5 to 21 5 km of uplift in the vicinity of haast pass 14 5 to 21 km near mt cook and 12 5 to 15 5 km in the arthur s pass transect adjacent to the alpine fault in the mount cook region the average uplift rate from 5 5 ma to 1 ma was 2 3 to 2 5 mm yr between 1 ma and the present it has averaged 6 2 mm yr the strongly asymmetric uplift pattern is responsible for the exposure of a 13 25 km wide belt of greenschist to midamphibolite facies rocks immediately east of the alpine fault known as the alpine schists 3 late cenozoic uplift of torlesse greywackes and alpine schists was preceeded during the jurassic early cretaceous by 5 8 km of uplift the otago schist belt to the south was uplifted much more during this interval and in addition western parts of the otago schists were uplifted 5 6 km during the late cretaceous 4 the fission track data do not support the notion of significant late cenozoic shear heating about the alpine fault as previously suggested from spatial variations in k ar ages of the otago and alpine schists

testing the fossil record sampling proxies and scaling in the british triassic jurassic the quality of the fossil record varies immensely across taxa geographic regions environments and time intervals because much of this variation can be confounded when examining global patterns we present a detailed investigation of the british triassic and jurassic one of the most intensively studied pairs of systems in the world marine jurassic palaeodiversity is at least partly controlled by rock availability and accessibility the terrestrial record is patchier and effects of rock availability are overprinted by a stronger signal of sporadic preservation these results also fit a sea level driven common cause explanation as one would expect to see close correlation between rock availability and palaeodiversity in the marine realm but less so in the terrestrial formation counts and palaeodiversity do not correlate a surprising result given the number of earlier studies that have found close correlations however this study differs from most others in that formation counts and palaeodiversity metrics are derived from independent data sources and so within study redundancy is avoided the study confirms the complexity of rock fossil time series and the likelihood that the fossil record documents a complex mix of potential biological signal common cause signal and rock record and sampling bias it may be impossible to identify a useful simple sampling proxy for the fossil record that captures every bias and sampling error ironically when preservation is good sampling proxies representing rock availability such as outcrop area can be used to predict palaeodiversity but are ineffectual when the fossil record is patchy

assessing sampling of the fossil record in a geographically and stratigraphically constrained dataset the chalk group of hampshire southern uk taphonomic geological and sampling processes have been cited as biasing richness measurements in the fossil record and sampling proxies have been widely used to assess this however the link between sampling and taxonomic richness is poorly understood and there has been much debate on the equivalence and relevance of proxies we approach this question by combining both historical and novel data a historical fossil occurrence dataset with uniquely high spatial resolution from the upper cretaceous chalk group of hampshire uk and a newly compiled 3d geological model that maps subsurface extent the geological model provides rock volumes and these are compared with exposure and outcrop area sampling proxies that have often been conflated in previous studies the extent to which exposure area true rock availability has changed over research time is also tested we find a trend of low cenomanian to high turonian to campanian raw richness which correlates with and is possibly driven by the number of specimens found after sampling standardization an unexpected mid turonian peak diversity is recovered and sampling standardized genus richness is best predicted by rock volume suggesting a species area or genus area effect additionally total exposure area has changed over time but relative exposure remains the same supplementary materials a locality list abundance matrix and all correlation and modelling results are available at https doi org 10 6084 m9 figshare c 3592208

the hidaka shear zone hokkaido japan genesis during a right lateral strike slip movement the mesozoic structure of hokkaido which is characterized by a wide spread ophiolite sequence unconformably overlain by a cretaceous flysch sequence is cut by a north south trending metamorphic belt the hidaka belt this contribution aims to demonstrate that the hidaka belt is a wide right lateral strike slip shear zone the movement is contemporaneous with the metamorphism and the magmatism of oligo miocene time

fission track analysis of the late cenozoic vertical kinematics of continental pacific crust south island new zealand during the late cenozoic the pacific plate has been converging obliquely with the australia plate in south island new zealand a result of this convergence has been the growth of a major mountain range the southern alps at the leading edge of the pacific plate the results of fission track analysis of 140 samples from 13 transects across the alps reported here establish the late cenozoic vertical kinematics amount age and rate of rock uplift of the pacific crust underlying the alps the late cenozoic rock uplift of the pacific crust is asymmetrical with respect to the alpine fault being a maximum 19 km immediately east of the central part of the fault with lesser values at the eastern 3 km northern 10 km and southern 8 km extremities of the alps the age of the start of rock uplift varies spatially across the southern alps the earliest indications from fission track analysis being at 8 ma at the southern end of the alps decreasing to 5 ma at the northern end and 3 ma along the southeastern margin this age variation reflects the longer time over which the southern parts of the alps have been in collision the rate of propagation of rock uplift southeastward into the pacific plate has been 30 mm yr nearly 4 times the late cenozoic average rate of convergence normal to the plate boundary late cenozoic mean rock uplift rates range from a maximum of 2 8 mm yr at the alpine fault to a minimum of 1 0 mm yr in the east and have been sustained for periods of 3 8 m y accompanying denudation has exhumed amphibolite grade rocks immediately east of the alpine fault the rock uplift has been controlled by oblique slip displacement on the alpine fault a continental crustal section at least 19 km thick has been uplifted on the alpine fault comparison of the late cenozoic mean rock uplift rates with uplift rates derived from reset zircon data 2 10 mm yr near the alpine fault shows that uplift has accelerated over time but only significantly since 1 3 0 3 ma the amount of mesozoic uplift ranged from minimal amounts north of arthur s pass to 3 km near mount cook to 10 km in the south at lake wanaka

sediment cycling on continental and oceanic crust sedimentary rocks are often described as declining in quantity with increasing age due to the cumulative effects of crustal deformation and erosion one important implication of such a model is that the geological record becomes progressively less voluminous and less complete with increasing age here we show that the predictions of a model in which the destruction of sedimentary rock is the predominant process signal are borne out only among sediments deposited on oceanic crust and among sediments deposited above sea level in non marine environments most of the surviving volume of sedimentary rock 75 was deposited in and adjacent to shallow seas on continental crust and does not exhibit any steady decrease in quantity with increasing age instead shallow marine sediments exhibit large fluctuations in quantity that were driven by shifting global tectonic boundary conditions such as those that occur during the breakup and coalescence of supercontinents the accumulation of sediments on the continents has not been uniform in rate but it does record a primary signal of net growth that has many implications for the long term evolution of earth s surface environment

thermal effects and timing of thrusting in the moine thrust zone illite crystallinity studies in the foreland to the moine thrust belt show a widespread heating event which is interpreted as a thermal response to thrust sheet emplacement temperatures reached 275 c approximately 24 ma after the main thrusting events based on the relationships between syn thrusting intrusions and the thrust planes combined with radiometric dates from the moine sheet it is argued that movement on the moine thrust started between 440 and 430 ma ago contractional slip in the moine thrust belt ceased at about 425 ma ago and it is proposed that illite metamorphism attained temperatures of 275 c at about 408 ma ago

shear heating associated with movement along the alpine fault new zealand abstract geothermometry based on the fe mg partitioning between biotite and garnet has revealed a temperature increase of circa 100 c associated with the development of schist derived mylonites that presently crop out within the alpine fault zone in new zealand calculations show that the temperature increase is compatible with a short shear heating event 1 5 10 5 years it has been tentatively associated with a possible high stress deformation 1 2 kbar which occurred when the then existent mylonites were unable to accommodate imposed strain rates because of the misorientation of their fabric elements during the change in the relative slip vectors between the pacific and australian plates in the late miocene early pliocene the high stress deformation resulted in the present mylonites which have their fabric elements orientated to accommodate the present oblique reverse slip movement between the two plates

macrostratigraphy of north america abstract the geological record is a three dimensional mosaic of gap bound rock bodies that at any given scale of temporal resolution were emplaced more or less continuously at any geographic location the irregular alternation of processes responsible for the formation and destruction of rock bodies results in the preservation of hiatus bound rock packages that have a distinct time of first occurrence base or oldest portion a time of last occurrence top or youngest portion and a suite of defining characters e g lithologies thickness fossils etc many important aspects of the geologic record can be quantified by compiling the stratigraphic ranges of such gap bound rock packages these include the quantity and spatial and temporal distribution of preserved rock rates of rock formation sequence stratigraphic architecture and area weighted rates of expansion and contraction erosional truncation of rock emplacement settings this approach to characterizing the rock record is scalable per

internal wave attenuation by coastal kelp stands abstract coastal kelp stands are a unique physical environment having high drag distributed throughout the water column temperature records from locations at increasing distances into the kelp show a damping of high frequency variance and a slowing of wave propagation at low frequencies this behavior at low frequencies is more a diffusion than a wave process linearized internal wave models incorporating linear drag successfully explain the frequency response of phase velocity but are less successful with the attenuation coefficient the attenuation coefficient is well explained by the model of the outer area of the kelp but is overestimated in the kelp stand interior in the outer area phase velocity is about 0 12 m s 1 at 100 cpd cycles per day a third of that at 1 cpd attenuation coefficient is 7 5 km 1 at 100 cpd 1 5 km 1 at 1 cpd

fault zone reactivation kinematics and mechanisms the kinematics and mechanisms of fault zone reactivation are reviewed reactivation is dependent upon fault zone orientation and the existence of weak mylonites along these zones the recognition of reactivation within mylonite zones and the softening processes that first concentrate deformation into these and secondly provide a weak medium for reactivation are discussed attention is given to the darling mobile zone western australia and the redbank zone see obee white this symposium as examples of reactivated zones

shallow level metamorphic fluids in a high uplift rat metamorphic belt alpine schist new zealand fluids some of which are co2 rich up to 40 mol co2 and some of which are highly saline up to 18 wt nacl equivalent are trapped as fluid inclusions in quartz calcite metallic minerals veins which cross cut the pumpellyite actinolite to amphibolite facies rocks of the alpine schist fluids were commonly trapped as immiscible liquid vapour mixes in quartz and calcite showing open space growth textures fluid entrapment occurred at fluid pressures near 500 bars possibly as low as 150 bars at temperatures ranging from 260 to 330 c saline fluids may have formed by partitioning of dissolved salts into an aqueous phase on segregation of immiscible fluids from a low density co2 rich fluid calcite deposited by these fluids has 13c ranging from 8 4 to 11 5 and 18o from 4 to 13 isotopic data fluid compositions and mode of occurrence suggest that the fluids are derived from high grade metamorphic rocks fluid interaction with wall rock has caused biotite crystallization and or recrystallization in some rocks and retrogression of biotite to chlorite in other rocks fluid penetration through the rock is almost pervasive in many areas where permeability probably related to alpine fault activity has focussed fluids on a regional scale into fractured rocks the fluid flow process is made possible by high uplift rates in excess of 10 mm year bringing hot rocks near to the surface

carbonate collapse and the late paleozoic ice age marine biodiversity crisis el set de datos contiente datos de la paleobiology database paleobbd org cruzados con los datos de macrostrat macrostrat org datos crudos de macrostrat y los scripts necesarios para reproducir el trabajo

mode of crustal shortening adjacent to the alpine fault new zealand the late cenozoic episode of crustal shortening in the south island new zealand which has caused present day uplift rates of greater than 10 mm yr and has formed the southern alps may have also caused clockwise rotation of the alpine fault by up to 20 in contrast to the northern end of the alpine fault which appears to have remained fixed relative to the australian plate increasing westward movement of the fault trace has occurred southward along the fault this westward movement may exceed 100 km where the fault crosses the coastline in northern fiordland most shortening adjacent to the southern end of the alpine fault has occurred within australian plate continental crust which has been thrust beneath pacific plate continental crust this zone of continental underthrusting merges with the fiordland subduction zone further south where australian plate oceanic crust is being subducted gravity modelling of the continental collision zone beneath the southern alps indicates that the leading edge of underthrust australian plate crust may be close to a relatively sharp 10 km change in moho depth inward dipping thrust faults on both plates mark the outer limits of the collision zone which is over 300 km wide near the southern end of the alpine fault the probable increase in crustal thickness due to the late cenozoic shortening suggests that the amount of crustal thickening is similar in size to the amount of eroded crust

the fossil record and spatial structuring of environments and biodiversity in the cenozoic of new zealand there is increasing evidence to suggest that drivers of bias in the fossil record have also affected actual biodiversity history so that controls of artefact and true pattern are confounded here we examine the role of spatial structuring of the environment as one component of this common cause hypothesis our results are based on sampling standardized analyses of the postmiddle eocene record of shelf molluscs from new zealand we find that spatial structuring of the environment directly influenced the quality of the fossil record contrary to our expectations however we find no evidence to suggest that spatial structuring of the environment was a strong or direct driver of taxic rates net diversity or spatial structuring in mollusc faunas at the scale of analysis stage to stage variation in sampling standardized diversity over the past 40 ma exhibits two superficially independent dynamics a changes in net diversity were associated primarily with changes in origination rate and b an unknown common cause related extinction rate to the quality of the fossil record and indirectly to spatial structuring of the environment we suggest that tectonic drivers manifest as second order sequence stratigraphic cycles are likely to have been a key element of this common cause our perceptions of biodiversity history are influenced strongly by secular biases in the quality of the fossil record e g raup 1976 peters foote 2001 many authors have argued against a literal reading of the record and various techniques to minimize the impacts of sampling biases have been developed e g connolly miller 2001 foote 2003 alroy 2010 in addition however a number of studies have proposed that the relationship between sampling biases and diversity dynamics may be complex these studies have suggested that there are latent common cause factors such as plate tectonics and sea level change which have affected simultaneously the quality of the fossil record and true macroevolutionary history e g newell 1952 sepkoski 1976 smith 2001 peters foote 2002 foote 2003 peters 2005 2006a wall et al 2009 demonstrating potential common causes separating their effects from simple preservation and sampling biases and interpreting them mechanistically are challenging problems that must be solved if palaeobiologists are to resolve true patterns and processes of macroevolutionary change through geological time the aim of the present paper is to examine the role of spatial structuring of the environment and of biodiversity in driving both macroevolutionary dynamics and biases in the fossil record fig 1 specifically we are interested in the extent to which partitioning of marine environments may have influenced biodiversity and the preservation of that diversity in part the study is founded on the expectation that the geographical range and evolution extinction dynamics of organisms occupying a particular habitat will be related to the area and fragmentation of that habitat e g rosenzweig 1995 maurer nott 1998 at the same time we anticipate that the quality of the marine fossil record will be influenced by for example the areal extent and distribution of depositional v non depositional or erosional environments factors that are also likely to affect habitat fragmentation and diversity to test the role of spatial structuring in the common cause hypothesis we use the exemplary well studied and relatively complete fossil record of post middle eocene level bottom shelf molluscs from new zealand e g crampton et al 2003 2006a this record is approximately from mcgowan a j smith a b eds comparing the geological and fossil records implications for biodiversity studies geological society london special publications 358 105 122 doi 10 1144 sp358 8 0305 8719 11 15 00 the geological society of london 2011 40 complete at the species level for the neogene as estimated using two very different approaches cooper et al 2006 crampton et al 2006a in this paper therefore we derive an index for spatial heterogeneity of the environment and adapt established indices of spatial differentiation in the new zealand cenozoic mollusc fauna we then compare time series of these measures to time series of sampling probability a proxy for the quality of the fossil record and sampling standardized estimates of overall species richness origination rate and extinction rate all analyses and computations reported here were undertaken using r r development core team 2010 materials and methods

mountain building strike parallel motion and mantle anisotropy abstract geophysical and geological evidence indicates that tectonic movements parallel to the strike of orogenic belts and suture zones are the most important mode of displacement during continental collision and oblique subduction several hundred to a few thousand kilometers of displacement may have occurred this way resulting in a pervasive ductile deformation of the lithosphere consequently both crustal and mantle fabrics may reflect these movements and their study using both geological and geophysical methods could supply important clues to lithosphere behavior during mountain building on the basis of kinematic analysis of ductilely deformed crustal rocks in zones of movement a variety of tectonic models have been proposed which differ in 1 1 the timing of strike parallel motions early before or during continental accretion or late after accretion was completed 2 2 the geometric pattern of strike parallel displacement zones low angle or high angle and 3 3 the location of orogen parallel movement zones in outboard terranes on the subducting plate along the suture zone or within the continental hangingwall large scale displacements parallel to mountain belts also suggest that they occurred along lithospheric faults rooted in the upper mantle although few studies have been carried out from this view point thermal structural and petrological data support the conclusion that lithospheric faults involving the upper mantle may be discriminated from crustal faults rooted in some crustal decoupling zone where available data on mantle flow beneath orogenic belts are in agreement with mountain parallel displacements inferred from crustal studies this has an important bearing on the seismic anisotropy pattern which can be predicted in the lithospheric mantle below mountain belts the fast velocity direction which is parallel to the flow direction should therefore be recorded parallel to the strike of the belt

new insight into the dynamic development of the southern alps new zealand from detailed thermochronological investigation of the mataketake range pegmatites

south island new zealand and transverse ranges california a seismotectonic comparison both the south island of new zealand and the transverse ranges of california have 1 a major right slip fault marking the plate boundary 2 a left stepping bend in the fault resulting in ranges and basins bounded by active reverse faults that strike 45 counterclockwise to the regional strike of the main fault 3 a set of right slip faults on one side of the constraining bend with most of the total displacement concentrated on the fault stepped farthest left from the continuation of the fault on the other side of the bend and 4 intersections between the set of faults and the main fault within the bend not present or poorly defined the faults with most of the displacement alpine wairau san andreas may pre date the constraining bend the reverse fault province southeast of the alpine fault is separated from that fault by the southern alps which may be underlain by crust that is too hot and too weak to sustain major reverse faults average reverse fault recurrence intervals in new zealand and california are 10 to 2 104 years as compared to less than 10 years for the right slip master fault seismicity is high but patchy in the nelson buller region of the northern south island low but patchy in the transverse ranges and very low in central otago in the southern south island all reverse fault provinces seismicity patterns in both regions poorly related to overall late quaternary fault distribution correspond largely to individual rupture events on portions of quaternary faults and the seismic inactivity of many of these faults may simply represent quiescence between seismic faulting with long recurrence intervals the geology and seismicity of the three reverse fault provinces support the suggestion of c r allen 1975 that late quaternary fault history is a better long term guide for assessment of large magnitude earthquake hazard than instrumental and historical seismicity for faults with long recurrence intervals

covariation in macrostratigraphic and macroevolutionary patterns in the marine record of north america students of earth history have long recog nized the correlation between the quantity of preserved sedimentary rock and the diversity of life recorded as fossils but paleontologists have yet to determine whether this pattern refl ects a causal relationship or a unidirec tional sampling bias in fossil data imposed by preserved rock quantity distinguishing between these two alternatives has been com plicated by the fact that many of the basic patterns of paleontologic and lithologic co variation have yet to be quantifi ed rigorously here we present the fi rst analyses of the co variation between the macrostratigraphic and macroevolutionary histories of north america based on geographically and tem porally explicit co occurrences of rocks and fossils the analyses use independent quan titative summaries of the stratigraphic and fossil records by integrating the paleobiology database paleodb and macrostrat a mac rostratigraphy database for north america which allows a more direct comparison of the stratigraphic and biological histories of the continent than has heretofore been possible within the macrostrat database the rock re cord is divided into discrete packages of sedi ment that are bound by hiatuses resolvable at the stage level using per interval per pack age rates of sediment package initiation and truncation and genus fi rst and last appear ances herein regional origination and extinc tion we fia substantially stronger positive correlation between sediments and biology for extinction like parameters than we do for origination like parameters four of the largest coincident pulses of regional extinc tion and sediment truncation occur during the widely recognized end ordovician late permian end triassic and end cretaceous mass extinction intervals a further compari son of the global ranges of north american genera to north american macrostratigra phy indicates that the regional and global extinction of genera are more likely to oc cur in the same stage than are global and regional originations together these results suggest that our general understanding of biodiversity dynamics from the fossil record may not be strongly biased by the preserva tion of sediments and leaves open the pos sibility that certain large perturbations to the earth system are responsible for major changes of state in both the sedimentary and biological systems

internal tide pools prolong kelp forest hypoxic events this study uses field observations within a single kelp bed in southern monterey bay california to evaluate the retention of cold hypoxic water within depressions in the rocky reef following relaxation of internal wave events just as tide pools in the rocky intertidal zone persist in depressions following the relaxation of surface waves and tides internal tide pools persist in depressions in the subtidal reef following the relaxation of internal waves when internal waves contain low dissolved oxygen do water the duration of hypoxic events can be extended for organisms within the pooling zone additionally we suggest that internal wave run up can cause the early arrival of cold hypoxic water in these same areas thereby extending hypoxic events further together internal tide pools and wave run up extend event durations by 20 on average however some events are extended up to 160 of the regional scale event length which may be more ecologically relevant than the mean extension when internal waves contain other environmental covariates e g low ph nutrients internal tide pools are expected to create a similar time extension and patchy landscape in these quantities we attribute the slowing of the relaxation of sub thermocline water within pooling zones to retention within the reef itself rather than a drag effect of the kelp bed following hypoxic internal bores internal tide pools cause a period of extreme spatial variability in the do and temperature field which is likely to impact the distribution and behavior of local organisms

thermal modeling of the southern alps new zealand finite element modeling of the thermal regime across the southern alps of new zealand has been carried out along two profiles situated near the franz josef and haast valleys the modeling involves viscous deformation beneath the southern alps including both uplift and erosion and crustal lithospheric thickening as a result of crustal shortening extending to 20 mm y of a 25 km thick crust published uplift rates and crustal thickness variations along the two profiles are used to constrain the modeled advection of crustal material and results are compared with the recent heat flow determinations 190 50 mw m2 in the franz josef valley and 90 25 mw m2 in the haast valley comparisons of the model with published k ar and fission track ages show that the observed heat flow in the franz josef valley is consistent with observed zircon fission track ages of around 1 ma if the present day uplift rate is close to 10 mm y major thermal differences between the franz josef and haast profiles appear to be due to different uplift and erosion rates there is weak evidence that frictional heating close to the alpine fault zone is not significant the modeling provides explanations for the distribution of seismicity beneath the southern alps and predicts a low surface heat flow over the eastern foothills due to the dominant thermal effect of crustal thickening beneath this region predicted temperatures at mid crustal depth beneath the zone of maximum uplift rate are 50 100 c cooler than those indicated in previously published models which implies that thermal weakening of the crust may not be the main factor causing the aseismicity of the central southern alps the results of the modeling demonstrate that the different types of reset age data in the region within 25 km of the alpine fault are critical for constraining models of the deformation and the thermal regime beneath the southern alps

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

tidal exchange at the bay ocean boundary for bays and inlets with narrow entrances tidal exchange with the ocean is often characterized by an ebb flood asymmetry in which the ebb flow exits the bay as a jet while the flood flow is drawn in approximately as a radial sink a process often termed tidal pumping in this paper the importance of tidal pumping in controlling the exchange of water at the bay ocean boundary is examined based on observations at the mouth of san diego bay the observations are novel in combining the use of shipboard acoustic doppler current measurements with a unique bay water tracer technique to provide visualization of the exchange as well as exchange budgets visualization of the tidal evolution of flow and tracers suggests that in accordance with the classical tidal pumping model the horizontal dynamics at the mouth of san diego bay are governed by an asymmetry between the jet like nature of the ebb flow and the sink like nature of the flood flow this asymmetry results in strong tidal velocity and phase gradients similar to those observed in previous numerical modeling studies a one dimensional trajectory model based on the observations indicates that the combined influence of the residual circulation and offshore gradients in the tidal velocity and phase provides the mechanism by which water from the bay is exchanged with water from the ocean both bottom friction and thermal gradients affect the dynamics of the vertical exchange the resulting asymmetry in the offshore flow leads to a vertical mode of pumping similar to that observed in the horizontal view this horizontal and vertical pumping of the offshore flow is shown to produce a strong correlation between the sectionally averaged velocity and bay water concentration resulting in a significant net tidal exchange between the bay and ocean

metamorphism and deformation mechanisms in the sierras australes fold and thrust belt buenos aires province argentina abstract the sierras australes fold and thrust belt is affected by an easternmost anchizonal metamorphism which grades into a western area of greenschist facies metamorphism both areas and their inferred boundary are distinguished on the basis of quartz recrystallization and illite crystallinity data during the first deformation pressure solution and grain boundary diffusion accompanied rigid body rotation and grain boundary gliding processes these mechanisms together with intracrystalline quartz deformation and recrystallization contributed to increasing rock ductility in the area of greenschist facies metamorphism two deformational events expressed by folding cleavage formation and thrusting were followed by static annealing of quartz which affects the southwestern part of the mountain range evidence for fluid and mass transfer also suggests convective fluid driven heat transport as an important mechanism for the final metamorphic overprint under static conditions

semi brittle deformation within the alpine fault zone new zealand abstract this paper reports the results of an attempt to identify the deformation micromechanisms in the brittle ductile transition zone of the alpine fault new zealand characterization of sequentially developed microstructures was carried out using optical microscopy hvem and stem analysis it was found that the transition zone corresponds to a broad zone of retrogression produced initially by microcracking and fluid infiltration the non catastropic nature of the fracturing indicates that fluid enhanced sub critical cracking is a significant crustal deformation mechanism after the initial phase of retrogression both ductile and brittle processes coexist and cyclically alternate in response to stress cycling the relative importance of macroscopic brittle processes may decrease with time as more ductile minerals especially phyllosilicates develop during continued retrogression

contrasting patterns and connections of rock and biotic diversity in the marine and non marine fossil records of north america abstract macrostratigraphy uses packages of continuous sedimentation that are bound by hiatuses of non deposition erosion or alternations between environments lithologies to characterize spatiotemporal patterns of sedimentation previous work has linked the macrostratigraphy of marine shelf environments to many different macroevolutionary patterns in the marine animal fossil record here we use an improved macrostratigraphic database for north america combined with fossil occurrence data in the paleobiology database to show that macroevolutionary and macrostratigraphic patterns are correlated more strongly in marine environments than in non marine environments we also test the hypothesis that the temporal distribution of lithological diversity measured as evenness similar to ecological evenness based on the number of lithostratigraphic units with a given lithologic type within each time interval has a relationship to genus level taxonomic diversity in both the marine and non marine realms uneven sampling of lithologies and their corresponding depositional environments can bias our perception of taxonomic diversity by causing taxa from poorly sampled environments to be underrepresented in the fossil record our results show a negative correlation between lithologic evenness and marine vertebrate generic richness less even sampling of lithologies corresponds to a higher observed taxonomic richness and no correlation with lithologic evenness and non marine diversity measures this suggests a difference in the relationship between biologic and sedimentary processes at work in the marine and non marine realms and possibly differences in the magnitude of the bias imposed by the rock record on the underlying biologic patterns

the development of discrete shear zones in a granite stress strain and changes in deformation mechanisms abstract the development of millimetre scale continuous shear zones in the sidi ali bou nab algeria granite and their progressive transformation into discrete shear zones are presented increases in strain stress and strain rate magnitudes as well as changes of deformation mechanisms are suggested by an evolution of the microstructure across these narrow shear zones temperatures are assumed to be constant from boundaries to core the most striking aspects of this evolution are 1 1 a decrease in the angle between the foliation and the shear zone 2 2 a decrease in the recrystallized grain size of quartz together with the development of a crystallographic orientation characterized by a strong concentration of c axes around the y axis of the finite strain ellipsoid 3 3 the development of very fine grained feldspathic aggregates or layers probably through dynamic recrystallization of original large crystals and 4 4 the replacement of original biotite by muscovite and a new generation of biotite in the continuous shear zones the deformation is controlled by the behaviour of quartz this mineral undergoes extensive dynamic recrystallization which probably favours a higher strain rate and a change in the active slip system from a dominant basal one in the outermost part of the structures to a dominant prismatic one in its core paleopiezometry and strain computations show a shear strain up to 10 and an inferred steady state differential stress to 100 130 mpa respectively the high stress level is suspect because the estimates are derived from recrystallized grain size which may be sensitive to strain and variations of chemical environment discrete shear zones develop in relation with dynamic recrystallization of feldspars in the core of continuous shear zones dynamic recrystallization of feldspars produces very fine grained aggregates grain size of 6 7 m which coalesce and form a continuous layer at the central part of the shear zones this fabric may result from 1 1 a change in the driving flow mechanism from dislocation creep of quartz to dislocation creep or and grain boundary sliding of feldspar neoblasts and 2 2 a large strain softening that would favour strain concentration in the fine grained matrix and the development of sharp shear zone boundaries

paleocene resurrection of a crocodylomorph taxon biotic crises climatic and sea level fluctuations abstract postcranial material of a crocodylomorph from the danian of oulad abdoun basin morocco is described several characters in particular the shape of its dorsal osteoderms allows its attribution to pholidosauridae up till now the latest known pholidosaurid was terminonaris from the early turonian of north america so the moroccan pholidosaurid extends the stratigraphic range of the group to more than 20 million years younger and shows that the pholidosaurids survived the k pg crisis the reevaluation and the phylogenetic analysis of dakotasuchus kingi woodbinesuchus byersmauricei and sabinosuchus coahuilensis previously considered as goniopholidids and dyrosaurid respectively revealed rather that they are pholidosaurids this analysis also suggests that at least two independent pholidosaurid lineages reached the maastrichtian among which one crossed the k pg boundary this study proposes the first analysis of tethysuchian diversity from the late jurassic to the early paleogene two diversity peaks are observed during the oxfordian and cenomanian two stages of high paleotemperatures evaluated with the 18o the tethysuchian diversity strongly decreases after the cenomanian a decline that may be correlated with the ocean anoxic event oae 2 which caused the strong marine faunal turnover during the cenomanian turonian time interval the large turonian coniacian oceanic regression could also be a factor in the tethysuchian decline after that tethysuchian diversity remains low until the maastrichtian lower paleocene marine tethysuchian dyrosaurid diversification correlated with the late cretaceous paleocene transgression at least one pholidosaurid lineage crossed the k pg boundary confirming the weak impact of this crisis on the crocodylomorphs pholidosaurids seem to go extinct at the beginning of the paleocene possibly due to the strong radiation of dyrosaurids in marine environments and crocodylians in fresh water during this time period

rates of processes in magmatic arcs implications for the timing and nature of pluton emplacement and wall rock deformation abstract the construction of arcs and in many cases the emplacement of plutons occur in tectonically active regions it is critical therefore to evaluate the rates of structural and magmatic processes when trying to understand the evolution of arcs and the associated pluton wall rock systems our best estimates of average rates or durations of processes in shallow to moderate level arc environments are the following 1 crystal growth rates in magma of 10 4 cm year 1 2 growth rates of metamorphic porphyroblasts between 10 5 and 10 2 cm year 1 3 long term magma supply rates of 10 1 km 3 year 1 and short term rates of up to 350 km 3 year 1 4 diapiric ascent rates for mafic plutons of 1 3 m year 1 5 cooling of plutons to ambient wall rock temperatures in 10 5 10 6 years 6 final crystallization of plutons in a small fraction of the time needed for complete cooling 7 fault displacements of 3 cm year 1 8 development of cleavages in fault zones in less than 10 6 years at strain rates of 10 13 s 1 or higher and 9 the development of regional cleavages in 10 6 years at strain rates of 10 14 s 1 these rates indicate that processes operating in magmatic arcs are relatively rapid pluton emplacement cleavage development etc occur over time spans of tens of thousands to no more than a few million years however the rate of ascent and crystallization of plutons at shallow levels is generally shorter than that needed to get large displacements on faults or widespread cleavages developed at deeper levels or in zones undergoing faster strain rates the time spans of the various processes approach one another thus plutons with otherwise similar characteristics emplaced in regions undergoing fast strain rates or at deeper crustal levels may appear quite different structurally from those emplaced at shallow levels or in regions undergoing slower strain rates comparison of these data also suggests that the rate at which wall rock deforms is the limiting factor controlling the rates of other structural processes during emplacement of plutons unless fast strain rates or multiple deformation mechanisms are considered thus emplacement mechanisms that rely on the transport of magma over 10 5 to 10 6 years are favored and need further consideration finally we argue that the structural and other characteristics of pluton wall rock systems will depend on rates of various processes involved and that these rates at the very least influence and sometimes invalidate the timing criteria previously published by us and others

deep seismic structure and thermo mechanical modelling of continental collision zones abstract a series of 2d thermo mechanical models are presented which quantify crustal thickening and the resulting temperature perturbations associated with thrusting in an attempt to constrain the existence of temperatures responsible for the generation of anatectic granites in a compressional environment deformation is assumed to occur in the crust by a simple thrusting mechanism the moho acting as a detachment surface as has been observed on deep seismic reflection data while the more ductile sub crustal lithosphere is assumed to behave elastically and deform in a pure shear manner investigated are the relative effects of the rate of crustal shortening the distribution of radioactive elements within the crust the reduced heat flow from the mantle isostasy and erosion our results show that previous oversimplified 1d models significantly overestimate the elevated temperatures in lower crustal regions caused by radiogenic heating and that this mechanism will only have a significant effect in regions of relatively thin lithosphere or where there are unusually high rates of radiogenic heating in the crust generation of synthetic p t t data for locations deep down in the lower crust enables us to quantify the temperatures produced following a period of compressional deformation providing insight into the time scales involved for the generation of crustal melt granites within an orogenic belt

significance of molluscan shell beds in sequence stratigraphy an example from the lower cretaceous mannville group of canada1 detailed study of marine shales the ostracod zone within a cretaceous third order transgressive regressive sequence in the alberta foreland basin reveals a systematic association between shell beds and parasequence scale flooding surfaces including surfaces of maximum flooding the ostracod zone a subsurface lithostratigraphic unit known as the calcareous member in outcrop consists of 10 20 m of black shale and bioturbated sandstones with many thin fossiliferous limestones parasequences shallowing up cycles 2 3 m thick were delineated within this transgressive unit based on lithology sedimentary structures degree of bioturbation dinoflagellate diversity total organic carbon and carbon sulphur ratios many flooding surfaces are firmgrounds or hardgrounds shell rich limestones occur in three different positions relative to these flooding surfaces and each has a distinctive bioclastic fabric and origin i base of parasequence shell beds bops lie on or just above flooding surfaces in the deepest water part of a parasequence they are thin up to a few centimetres graded or amalgamated skeletal packstones wackestones composed of well sorted granular shell and are interpreted as hydraulic event concentrations of exotic shell debris ii top of parasequence shell beds tops are capped by flooding surfaces at the top shallowest water part of a parasequence they typically are several decimetres thick are physically amalgamated packstones grainstones or bioturbated wackestones and contain abundant whole as well as comminuted shells these are composite multiple event concentrations of local shells iii mid sequence shell beds rest on as well as are capped by firmgrounds or hardgrounds and are intercalated between parasequences in the deepest water part of the larger sequence they are laterally extensive lime mudstones a few decimetres thick with sparse shells in various states of dissolution recrystallization and replacement these beds are terrigenous starved hiatal concentrations and record maximum flooding within the ostracod zone offshore sections of the ostracod zone typically contain several starved mid sequence shell beds underscoring the difficulty of identifying a single maximum flooding surface within a third order sequence