inherited smnd isotope components preserved in monazite inclusions within garnets in leucogneiss from east antarctica and implications for closure temperature studies abstract application of the sm nd dating technique using garnet can be hampered by the presence of minor microscopic to submicroscopic ree rich inclusions in particular monazite and to a lesser extent zircon an acid leaching method using a mixture of hno 3 hcl has been used to tackle the monazite contamination problem with this leaching technique we demonstrate that inherited monazite inclusions have been preserved in garnet formed under high grade metamorphic conditions even very low levels of monazite contamination 0 001 wt have a profound effect on the sm nd system in the garnet analysis of a garnet from a leucogneiss dyke in the northern prince charles mountains eastern antarctica reveals that unleached garnet concentrates and the monazite inclusions as represented by the leachates define an apparent isochron of 1150 30 ma mswd 1 88 which represents a mixing age of inclusions preserving their inherited sm nd isotopic systematics in contrast analyses of the leached garnet concentrates yield much younger ages of 630 to 555 ma model calculations show that the presence of as little as 0 01 wt of monazite inclusions would swamp the sm nd isotope signature of the garnet concentrates this very low level of contamination is beyond the reach of physical purification processes and without leaching contamination is inevitable in inclusion bearing garnets such contamination can lead to older apparent ages than those of garnet formation and thus has profound implications for sm nd as well as u pb garnet chronometry

experimental calibration of the aluminum in hornblende geobarometer with application to long valley caldera california volcanic rocks a new geobarometer based on the al content of igneous hornblendes in equilibrium with melt fluid biotite quartz sanidine plagioclase sphene and magnetite or ilmenite has been calibrated experimentally the calibration was performed by equilibrating the required phase assemblage over the pressure range 2 8 kbar at 740 780c and then analyzing euhedral hornblendes in equilibrium with glass melt experiments were performed on natural samples of both volcanic and plutonic rocks earlier empirical calibrations of this geobarometer relied on analyzing natural hornblendes from plutons with the required phase assemblage and inferring pressure from nearby metamorphic country rocks the experimental calibration differs from the empirical calibrations especially above 5 kbar and shows that the al content of hornblendes in equilibrium with the required phase assemblage is greater for a given total pressure than previously thought the geobarometers uncertainty is dramatically reduced the derived equation is p plus minus 0 5 kbar 3 minus 3 46 plus minus 0 24 4 23 plus minus 0 13 al sup t the geobarometer is applied to post bishop tuff volcanic rocks from long valley caldera california and reveals that most rhyodacites in this complex erupted from depths of about 6 km these eruptions occurred over 500 000 yr suggesting that the rhyodacitic magma reservoir beneath longmore valley had reached a steady p depth t state less

late archaean terrane accretion in the godthab region southern west greenland tectono stratigraphic terranes fault bounded blocks of the earth s crust characterized by a geological history distinct from that of adjacent terranes1 are now widely recognized in phanerozoic and proterozoic orogenic belts and their present configurations are thought to result from plate tectonic processes similar to those in operation today2 4 there has been much debate about whether such processes operated in archaean times5 6 here we present new data from the archaean high grade gneiss complex of the godthab now nuuk region of southern west greenland which show that discrete tectonic units recognized in the south of the region7 can be more widely identified at least four terranes are recognized each of which evolved separately until their juxtaposition in the late archaean this suggests that at least some archaean high grade gneiss complexes may resemble more recent orogenic belts formed by plate tectonic processes

palaeoclimate interpretations of late pleistocene vegetated linear dune mobilization episodes evidence from the northwestern negev dunefield israel abstract the vegetated linear dune vld field of the northwestern nw negev desert situated at the downwind eastern end of the northern sinai nw negev erg constitutes an ideal setting for dating and interpreting its late quaternary dune encroachment episodes this study builds upon the results of roskin et al age origin and climatic controls on vegetated linear dunes in the northwestern negev desert israel quaternary science reviews 30 2011 1649 1674 that presented the stratigraphy of 35 sections and 97 optically stimulated luminescence osl ages from the nw negev dunefield here we refine our analysis of the negev late pleistocene dune mobilizations and stabilizations and interpret their palaeoclimatic controls in light of regional and global sediment records and proxies while initial dune encroachment into and stabilization in the nw negev took place during the last glacial maximum lgm at 23 18 ka spatial and statistical analyses of the osl dataset suggest that since the lgm negev dune activity was concentrated in two significant mobilization stabilization episodes a main episode at 16 13 7 ka and a minor one at 12 4 11 6 ka when the dunes reached their maximum spatial extent and stabilized these episodes include rapid dune encroachment and accretion events and coincide with the heinrich 1 and younger dryas cold events respectively the late pleistocene sand transporting winds were characterized by a westerly direction that resulted in west east vld elongation dune mobilizations may have occurred in response to wintertime east mediterranean cyclonic systems that brought storms of rainfall and strong winds the rapid dune mobilization events and their concurrence with the heinrich 1 and younger dryas cold events suggest a more global control despite the rainfall the elongating vlds were probably sparsely vegetated because of the high wind power their stabilization resulted from a decrease in storminess with the onset of a more arid holocene climate other global low latitude dune mobilizations and stabilizations are concentrated at the end of the late pleistocene leading us to suggest that these were also controlled mainly by global cold events and subsequent changes in windiness the recurring discontinuous aeolian sedimentation pattern found in osl dated vlds provides new and important chronological and sedimentological insight into prominent dune mobilization and stabilization processes the suggested link between global drops in cold event windiness and low latitude dune stabilization episodes emphasizes the prevalence of winds over aridity regarding major dune mobilizations for low latitude dunes even if vegetated

icesat derived inland water surface spot heights accurate measurement of water surface height is key to many fields in hydrology and limnology satellite radar and laser altimetry have been shown to be useful means of obtaining such data where no ground gauging stations exist and the accuracy of different satellite instruments is now reasonably well understood past validation studies have shown water surface height data from the icesat instrument to have the highest vertical accuracy mean absolute errors of 10 cm for icesat compared for example with 28 cm from envisat yet no freely available source of processed icesat data currently exists for inland water bodies here we present a database of processed and quality checked icesat derived inland water surface heights iwsh for water bodies greater than 3 arc sec 92 m at the equator in width four automated methods for removing spurious observations or outliers were investigated along with the impact of using different water masks we find that the best performing method ensures that observations used are completely surrounded by water in the srtm water body data using this method for removing spurious observations we estimate transect averaged water surface heights at 587 292 unique locations from 2003 to 2009 with the number of locations proportional to the size of the river

age origin and climatic controls on vegetated linear dunes in the northwestern negev desert israel abstract the stabilized northwestern nw negev vegetated linear dunes vld of israel extend over 1300 km 2 and form the eastern end of the northern sinai nw negev erg this study aimed at identifying primary and subsequent dune incursions and episodes of dune elongation by investigating dune geomorphology stratigraphy and optically stimulated luminescence osl dating thirty five dune and interdune exposed and drilled section were studied and sampled for sedimentological analyses and osl dating enabling spatial and temporal elucidation of the nw negev dunefield evolution in a global perspective the nw negev dunefield is relatively young though sporadic sand deposition has occurred during the past 100 ka dunes began to accumulate over large portions of the dunefield area only at 23 ka three main chronostratigraphic units corresponding to three osl age clusters were found throughout most of the dunefield indicating three main dune mobilizations late to post last glacial maximum lgm at 18 11 5 ka late holocene 2 0 8 ka and modern 150 8 years the post lgm phase is the most extensive and it defined the current dunefield boundaries it involved several episodes of dune incursions and damming of drainage systems dune advancement often occurred in rapid pulses and the orientation of vld long axes indicates similar long term wind directions the late holocene episode included partial incursion of new sand reworking of late pleistocene dunes as well as limited redeposition the modern sand movement only reactivated older dunes and did not lengthen vlds this aeolian record fits well with other regional aeolian sections we suggest that sand supply and storage in sinai was initiated by the late pleistocene exposure of the nile delta sands late pleistocene winds substantially stronger than those usually prevailing since the onset of the holocene are suggested to have transported the dune sands across sinai and into the northwestern negev our results demonstrate the sensitivity of vegetated linear dunes located along the northern fringe of the sub tropical desert belt to climate change i e wind and sediment supply

p t t development of archaean granulites in varpaisjarvi central finland i effects of multiple metamorphism on the reaction history of mafic rocks abstract medium pressure granulites are exposed as fault separated blocks in the varpaisjarvi area central finland they underwent a multi stage metamorphic development from the mid archaean to palaeoproterozoic partial melting of compositionally basaltic and andesitic rocks produced garnet plagioclase and pyroxene bearing restitic granulites at 9 11 kbar and 800 c 900 c ferromagnesian phases in leucosomes are iron rich giving slightly lower pressures than those in mesosomes which suggests that decompression promoted melting peak conditions were followed by cooling and decompression to around 700 c and 7 kbar fe rich and mg rich whole rock compositions show different reactions during decreasing pressure and temperature reflecting the dp dt slope differences between mg and fe endmember reactions in mg rich compositions garnet broke down in the reaction grt cpx qtz opx pl producing pseudomorphs after garnet whereas in fe rich rocks garnet was a product of reactions cpx pl grt qtz and scp cpx grt co2 mg rich basaltic mafic granulites have small abundances of internal leucosomes whereas in more fe rich andesitic compositions migmatization was more intense small quartz plagioclase films are often present between pyroxenes amphiboles and garnets representing remnants of melt that was expelled from the restitic mafic granulites in the northwestern parts of the granulite terrane pressures are higher than elsewhere which indicates that they represent a deeper section of the crust the second metamorphic event at lower pressure conditions produced orthopyroxene hornblende anorthitic plagioclase symplectites on garnet rims and fractures and opx pl and cpx pl symplectites on hornblende rims this seems to be connected with the semibrittle fracturing of the bedrock either during the emplacement of the palaeoproterozoic dolerites at 2 3 2 1 ga or during the svecofennian orogeny at 1 89 1 88 ga hydration connected with this event produced epidote filled fractures

sm nd dating and cooling history of scourian granulites sutherland the scourian gneisses of the lewisian complex of north west scotland have been the subject of many geochronological investigations sm nd whole rock measurements suggest that the protoliths of the lewisian complex differentiated 2 92 0 05 gyr ago from an approximately chrondritic mantle1 rb sr and pb pb whole rock ages between 2 8 and 2 6 gyr reflect subsequent depletion in rb and u refs 2 3 which has generally been associated with granulite facies metamorphism zircons which are thought to have crystallized during this metamorphism have also given u pb ages of 2 66 gyr ref 4 this granulite facies metamorphism involving pressures in excess of 10 kbar and peak temperatures estimated between 820 50 c ref 5 and 1 250 c refs 6 7 affects a terrain including supracrustal rocks7 and thus implies a major tectonic event we report here the first geochronological data measured on mineral assemblages that have also provided estimates of the conditions of metamorphism such measurements are possible because the major minerals of granulite facies assemblages show an unusually favourable spread in sm nd ratios garnet especially is strongly enriched in sm ref 8 data for three garnetiferous basic gneiss assemblages suggest that closure of the sm nd system occurred significantly later than the peak of the metamorphism

geochronology of an archaean tonalitic gneiss dome in northern finland and its relation with an unusual overlying volcanic conglomerate and komatiitic greenstone archaean gneiss greenstone relationships are still unresolved in many ancient cratonic terrains although there is growing evidence that most of the late archaean greenstone assemblages were deposited on older tonalitic crust

a simple raster based model for flood inundation simulation in this paper the development of a new model for simulating flood inundation is outlined the model is designed to operate with high resolution raster digital elevation models which are becoming increasingly available for many lowland floodplain rivers and is based on what we hypothesise to be the simplest possible process representation capable of simulating dynamic flood inundation this consists of a one dimensional kinematic wave approximation for channel flow solved using an explicit finite difference scheme and a two dimensional diffusion wave representation of floodplain flow the model is applied to a 35 km reach of the river meuse in the netherlands using only published data sources and used to simulate a large flood event that occurred in january 1995 this event was chosen as air photo and synthetic aperture radar sar data for flood inundation extent are available to enable rigorous validation of the developed model 100 50 and 25 m resolution models were constructed and compared to two other inundation prediction techniques a planar approximation to the free surface and a relatively coarse resolution two dimensional finite element scheme the model developed in this paper outperforms both the simpler and more complex process representations with the best fit simulation correctly predicting 81 9 of inundated and non inundated areas this compares with 69 5 for the best fit planar surface and 63 8 for the best fit finite element code however when applied solely to the 7 km of river below the upstream gauging station at borgharen the planar model performs almost as well 83 7 correct as the raster model 85 5 correct this is due to the proximity of the gauge which acts as a control point for construction of the planar surface and the fact that here low lying areas of the floodplain are hydraulically connected to the channel importantly though it is impossible to generalise such application rules and thus we cannot specify a priori where the planar approximation will work simulations also indicate that for this event at least dynamic effects are relatively unimportant for prediction of peak inundation lastly consideration of errors in typically available gauging station and inundation extent data shows the raster based model to be close to the current prediction limit for this class of problem q 2000 elsevier science b v all rights reserved

locally modified surface winds on linear dunes as derived from directional raingauges the study deals with local airflow patterns induced by 12 16 m high partly vegetated dunes under various prevailing wind conditions detailed empirical data were derived by means of an unconventional use of directional raingauges the utility and accuracy of the method have been previously tested in a combined empirical and numerical study over ridges on a similar scale results are presented on the nature extent and intensity of locally modified patterns of surface flow and on their dependence on wind conditions and slope inclination results may serve to verify or refine existing perceptions or models of the flow affecting sand movement over dunes for example deflected surface wind flow and even stationary vortices were found to form under winds with resultant angles of incidence of only 5 10 relative to the axes of the dunes and on slopes inclined only 12 15 i e lower angles than often assumed in previous studies of dune morphology various effects of the resulting surface flow on the dune ecosystem are also referred to e g the distribution of settling dust and seed dispersal copyright 2002 john wiley sons ltd

nd and sr systematics in an eclogite xenolith from tanzania evidence for frozen mineral equilibria in the continental lithosphere combined isotopic nd sr and petrographic analyses are reported for an eclogitic xenolith from the vissury mine tanzania an exceedingly large difference in measured nd values in garnet and clinopyroxene 200 units suggest a major mineral equilibration at 1 75 0 014 ga nd isotopic heterogeneities are demonstrated in different generations of garnet and zonation in sr and nd isotope compositions is present within the clinopyroxene the variation in measured nd isotope compositions in different generations of garnet corresponds to 16 units exsolution of garnet from clinopyroxene occurred in an essentially closed system with respect to sr and nd petrographically different generations of garnet are present one garnet with rutile inclusions as well as the rims of clinopyroxene are clearly off the isochron features like this can originate either if a system is not closed e g affected by a migrating fluid or if a remanent isotopic heterogeneity survived the homogenisation at 1 75 ga the subsolidus partitioning of sm and nd between garnet and clinopyroxene results in higher fractionation of the smnd ratio in garnet than in the liquid crystal partitioning since the closure temperature for the sm nd exchange between garnet and clinopyroxene may be around 850 c in a dry system many of the lithospheric ultramafic rocks may exhibit frozen mineral equilibria the isotopic data suggest that this eclogite was emplaced at 1 75 ga into the lithosphere mantle at temperatures of about 1040 c and then cooled as a closed system at a rate of 6 50 c my down to 840 c where all the exchange reactions were efficiently frozen in at 1 75 ga ago the coincidence of the emplacement of granites 1 7 1 8 ga into the central part of the tanzanian craton with the age of the eclogite suggests that lower crustal melting was triggered by a thermal event in the upper lithosphere

a morphology independent methodology for quantifying planview river change and characteristics from remotely sensed imagery abstract remotely sensed imagery of rivers has long served as a means for characterizing channel properties and detection of planview change in the last decade the dramatic increase in the availability of satellite imagery and processing tools has created the potential to greatly expand the spatial and temporal scale of our understanding of river morphology and dynamics to date the majority of gis and automated analyses of planview changes in rivers from remotely sensed data has been developed for single threaded meandering river systems these methods have limited applicability to many of the earth s rivers with complex multi channel planforms here we present the methodologies of a set of analysis algorithms collectively called spatially continuous riverbank erosion and accretion measurements scream scream analyzes planview river metrics regardless of river morphology these algorithms quantify both the erosion and accretion rates of riverbanks from binary masks of channels generated from imagery acquired at two time periods additionally the program quantifies the area of change between river channels and the surrounding floodplain and area of islands lost or formed between these two time periods to examine variations in erosion rates in relation to local channel attributes and make rate comparisons between river systems of varying sizes the program determines channel widths and bank curvature at every bank pixel scream was developed and tested on rivers with diverse and complex planform morphologies in imagery acquired from a range of observational platforms with varying spatial resolutions validation and verification of scream generated metrics against manual measurements show no significant measurement errors in determination of channel width erosion and bank aspects scream has the potential to provide data for both the quantitative examination of the controls on erosion rates and for the comparison of these rates across river systems ranging broadly in size and planform morphology

rainfall runoff relationship over encrusted dune surfaces nizzana western negev israel a thin microbial crust covers the lower part of longitudinal dunes in the western negev where average annual rainfall is 95 mm in order to study the effect of the microbial crust on rainfall runoff relationships under natural rainfall conditions runoff plots equipped with pressure gauges were established on opposite north and south facing slopes that differ in their vegetal cover and crust properties the study covered four years 1990 94 the first two years were wet and the following two years relatively dry one to five flow events were recorded per year no correlation was found between runoff yield rain amount and rain intensity unlike many microbial crusts reported in the literature the microbial crust in the western negev is not hydrophobic infiltration rate is high under dry surface conditions and of the order of 9 12 mm h 1 when the crust is saturated the high final infiltration rate is explained by the occurrence of large pores that do not seal when the crust is saturated typical hydrographs have very steep rising and falling limbs pointing at a limited contributing area most flows last less than 10 min and runoff volumes collected are on the whole very small owing to differences in crust properties runoff is higher on north than on south facing slopes 1997 john wiley sons ltd

floodplain channel morphology and networks of the middle amazon river 1 floodplain channels are important components of river floodplain systems and are known to play a key role in hydrodynamic exchange and sediment transport the amazon floodplain exhibits complex networks of these channels and despite their potential importance to this globally important wetland system these floodplain channels are relatively unstudied the research presented here is the first systematic and detailed study of the network and morphologic characteristics of a large number of these channels in the middle reach of the central amazon river using analysis of data derived from landsat enhanced thematic mapper plus etm mosaic and field survey our findings show that the channels are ubiquitous their width varies widely and some of their characteristics can be fitted using power laws potentially much like the self similar or fractal like behavior hypothesized for other types of fluvial networks in all 96 of the floodplain channels are not wide enough to be represented well or at all in the 90 m shuttle radar topography mission data channel depths are tied closely to the local amplitude of the passing main river flood wave p value of 0 75 except where there are local runoff inputs which results in substantially deeper channels which provide preferential flow paths across the floodplain channel networks imply that areas of the floodplain function for large parts of the flood cycle as separate hydrogeomorphic land units here termed floodplain hydrological units fhus these hypothesized fhus also have distinct spatial and pattern characteristics and it is suggested here that their differences could provide the beginnings of a framework for understanding the detailed hydrodynamics of the floodplain in particular different types of fhus have differences in flood water source which will have important implications for biogeochemical studies of the wetlands

large scale fluid infiltration metasomatism and re equilibration of archaean basement granulites during palaeoproterozoic thrust belt construction ungava orogen canada abstract the metamorphic history of the archaean superior province crystalline basement in the palaeoproterozoic ungava orogen attests to the importance of structural and geohydrological controls on a retrograde amphibolite granulite transition two distinct metamorphic suites separated in age by nearly one billion years are recognized in extensively exposed tonalitic to dioritic metaplutonic gneisses the older suite comprises c 2 7 ga granulite facies assemblages orthopyroxene clinopyroxene hornblende plagioclase ilmenite biotite quartz that record moderate pressures 5 kbar and high temperatures 800 c a younger c 1 8 ga suite resulted from amphibolitization of the granulites and is characterized by regionally extensive amphibolite facies mineral zones that broadly parallel the basal decollement of the overlying proterozoic cape smith thrust belt deformation mineral growth relationships in the amphibolitized basement indicate that extensive hydration and re equilibration of the archaean granulites occurred during thrust belt deformation the transition from granulite facies to amphibolite facies assemblages is characterized by the growth of garnet hornblende quartz cummingtonite coronas between plagioclase and orthopyroxene clinopyroxene as well as titanite coronas on ilmenite multi equilibrium thermobarometry on the coronitic assemblages documents re equilibration of the granulitic gneiss to 7 7 kbar at 644 c in the south and 9 8 kbar at 700 c in the north the variably deformed amphibolite facies domain sandwiched between the coronitic garnet zone and the basal decollement is marked by significant metasomatic changes in major element concentrations within tonalite these changes are compatible with equilibrium flow of an aqueous chloride fluid down a temperature gradient the source of fluids for basement hydration metasomatism is interpreted to be dehydrating clastic rocks in the overlying thrust belt with fluid flow probably focused along the basal decollement

pb u and th diffusion in natural zircon zircon zrsio4 is one of the most widely used minerals for determining the age origin and thermal history of rocks by u th pb geochronology but the parameters describing the solid state volume diffusion rates of these elements in natural zircon which are themselves important for establishing the limits on the applicability of zircon for geochronological studies have remained poorly quantified1 this is because of the measurement difficulties associated with the low p p m concentrations and low diffusion rates of these elements in natural zircon and the chemical and physical heterogeneity present in most crystals here we present direct measurements of the uranium thorium and lead loss from a thermally treated gem quality natural zircon and show that lead diffuses much faster than uranium or thorium we find that the u th pb isotopic system in natural zircon will typically have a closure temperature greater than 900 c which explains why zircon is apparently such a robust geochrometer and is capable of remaining isotopically closed through extended periods of high grade metamorphism and partial melting of the host rock

a simple global river bankfull width and depth database 1 hydraulic and hydrologic modeling has been moving to larger spatial scales with increased spatial resolution and such models require a global database of river widths and depths to facilitate accurate river flow routing hydraulic geometry relationships have a long history in estimating river channel characteristics as a function of discharge a simple near global database of bankfull widths and depths along with confidence intervals was developed based on hydraulic geometry equations and the hydrosheds hydrography data set the bankfull width estimates were evaluated with widths derived from landsat imagery for reaches of nine major rivers showing errors ranging from 8 to 62 correlation of 0 88 although it was difficult to verify whether the satellite observations corresponded to bankfull conditions bankfull depth estimates were compared with in situ measurements at sites in the ohio and willamette rivers producing a mean error of 24 the uncertainties in the derivation approach and a number of caveats are identified and ways to improve the database in the future are discussed despite these limitations this is the first global database that can be used directly in hydraulic models or as a set of constraints in model calibration

regional flood dynamics in a bifurcating mega delta simulated in a global river model in this paper we show the importance of bifurcation channels for flow in river mega deltas through the use of a new computational scheme implemented in the global hydrodynamic model cama flood catchment based macro scale floodplain model first we developed a new river network map based on srtm3 dem shuttle radar topography mission 3 arc second digital elevation model and hydrosheds hydrological data and maps based on shuttle elevation derivatives at multiple scales which includes bifurcation channels next we implemented a new bifurcation scheme in cama flood capable of routing flow along this network and used the model to simulate the mekong river we show that in the mekong delta such channels route about 50 of total flow and that their representation is essential for realistic hydrodynamic simulations a simulation without bifurcation channels was obviously unrealistic because no flow occurred between the mainstem and adjacent channels even when their water level difference was 6 m the bifurcation channels are extracted from globally available data sets thus it is straightforward to expand the proposed scheme to global scale studies

the origins of granulites a metamorphic perspective although many recent reviews emphasize a uniformity in granulite pressure temperature p t conditions and paths granulites in reality preserve a spectrum of important petrogenetic features which indicate diversity in their modes of formation a thorough survey of over 90 granulite terranes or occurrences reveals that over 50 of them record p t conditions outside the 7 5 1 kbar and 800 50 c average granulite regime preferred by many authors in particular an increasing number of very high temperature 900 1000 c terranes are being recognized both on the basis of distinctive mineral assemblages and geothermobarometry petrogenetic grid and geothermobarometric approaches to the determination and interpretation of p t histories are both evaluated within the context of reaction textures to demonstrate that the large range in p t conditions is indeed real and that both near isothermal decompression itd and near isobaric cooling ibc p t paths are important amphibolite granulite transitions promoted by the passage of co 2 rich fluids as observed in southern india and sri lanka are exceptional and not representative of fluid related processes in the majority of terranes it is considered on the contrary that fluid absent conditions are typical of most granulites at or near the time of their recorded thermal maxima itd granulites are interpreted to have formed in crust thickened by collision with magmatic additions being an important extra heat source erosion alone is not however considered to be the dominant post collisional thinning process instead the itd paths are generated during more rapid thinning 1 2 mm yr exposure related to tectonic exhumation during moderate rate or waning extension ibc granulites may have formed in a variety of settings those which show anticlockwise p t histories are interpreted to have formed in and beneath areas of voluminous magmatic accretion with or without additional crustal extension ibc granulites at shallow levels very rapid 5 mm yr extensional thinning subsequent to collision it is suggested that the preservation of ibc paths rather than itd paths in many granulites is primarily related to the rate and timescale of extensional thinning of thickened crust and that hybrid itd to ibc paths should also be observed most ibc granulites and probably many itd granulites have not been exposed at the earth s surface as a result of the tectonic episodes which produced them but have resided in the middle and lower crust for long periods of time 100 2000 ma following these events the eventual exhumation of most granulite terranes only occur through their incorporation in later tectonic and magmatic events unrelated to their formation

development of the global width database for large rivers river width is a fundamental parameter of river hydrodynamic simulations but no global scale river width database based on observed water bodies has yet been developed here we present a new algorithm that automatically calculates river width from satellite based water masks and flow direction maps the global width database for large rivers gwd lr is developed by applying the algorithm to the srtm water body database and the hydrosheds flow direction map both bank to bank river width and effective river width excluding islands are calculated for river channels between 60s and 60n the effective river width of gwd lr is compared with existing river width databases for the congo and mississippi rivers the effective river width of the gwd lr is slightly narrower compared to the existing databases but the relative difference is within 20 for most river channels as the river width of the gwd lr is calculated along the river channels of the hydrosheds flow direction map it is relatively straightforward to apply the gwd lr to global and continental scale river modeling

structural correlation within the kapuskasing uplift comparison of progressive deformation and metamorphic history within and between the tectonic domains of the kapuskasing uplift indicates significant variation in age and style of deformation across this large segment of the central superior province multiple stages of tonalite and granitoid intrusion melt generation polyphase diachronous deformation and likely rapid deep burial of supracrustal rocks collectively produced the complex character of this example of archean mid to deep crust at least four archean deformation phases are recognized although not all are of regional extent dated structural chronology suggests that the locus of the earliest recorded deformations migrated to deeper crustal levels with time pre 2680 ma deformation local d d within high level tonalites is correlated with deformation in the michipicoten supracrustal belt the apparent earliest deformational fabrics at deeper crustal levels in the granulite terrane of the kapuskasing structural zone occurred between 2660 and 2640 ma archean third and fourth phase deformation phases 2667 to 2629 ma are present at mid crustal and deeper levels and deform post 2667 ma metaconglomerate these resulted in large scale folding and subhorizontal ductile shear zones which seem to represent an important transitional zone that separated a passive upper crust from continued ductile strain at deeper levels subsequent uplift of the high grade rocks was accomplished in multiple stages initiated prior to 2 45 ga and likely culminated around 1 9 ga although continued movement occurred as late as 1 14 ga the ivanhoe lake fault zone along which much of the uplift must have occurred exhibits some evidence of ductile deep thrust related fabrics but most of the observed structures are brittle to brittle ductile and steeply inclined a broad zone of pervasive cataclasis and brittle ductile shear zones is a characteristic feature of the fault zone throughout its length and both dextral and sinistral offset are locally present clear ground evidence for major transcurrent or thrust displacements however has not been recognized

an empirical model of aeolian dune lee face airflow airflow data gathered over dunes ranging from 60 m tall complex crescentic dunes to 2 m tall simplecrescentic dunes were used to develop an empirical model of dune lee face airflow for straight crested dunes the nature of lee face flow varies and was found to be controlled by the interaction of at least three factors dune shape the incidence angle between the primary wind direction and the dune brinkline and atmospheric thermal stability three types of lee face flow separated attached and deflected along slope or attached and undeflected were found to occur separated flows characterized by a zone of low speed 0 3o of crestal speed back eddy flow typically occur leeward of steep sided dunes in transverse flow conditions unstable atmospheric thermal stability also favours flow separation attached flows characterized by higher flow speeds up to 84 of crestal speed that are a cosine function of the incidence angle typically occur leeward of dunes that have a lower average lee slope and are subject to oblique flow conditions depending on the slope of the lee face attached flow may be either deflected along slope lee slopes greater than about 20 or have the same direction as the primary flow lee slopes less than about 20 neutral atmospheric thermal stability also favours flow attachment as each of the three types of lee face flow is defined by a range of wind speeds and directions the nature of lee face flow is intimately tied to the type of aeolian depositional process i e wind ripple or superimposed dune migration grainflow or grainfall that occurs on the lee slope and the resulting pattern of dune deposits therefore the model presented in this paper can be used to enhance the interpretation of palaeowind regime and dune type from aeolian cross strata

late holocene dune mobilizations in the northwestern negev dunefield israel a response to combined anthropogenic activity and short term intensified windiness abstract the study of the effects of past climates on ancient cultures is usually based on geologic records pertaining to rainfall and temperature fluctuations and shifts this study proposes a paradigm of anthropogenic activity and windiness fluctuations to explain aeolian sedimentation and dune mobilization in the northwestern nw negev desert dunefield israel the proposed paradigm contributes a different approach to estimating the effect of climate changes on the unprecedented agricultural and urban settlement expansion during the late roman to early islamic period in the northern and central negev desert this study builds upon the late holocene cluster of luminescence ages coupled with analysis of archaeological finds and historical texts whereas the nw negev dunefield was generally stable during the holocene intermittent dune mobilization during the late holocene at 1 8 ka and mostly 1 4 1 1 ka 600 900 ce are linked to periods of human occupation the idea that the last glacial dune encroachments alone that formed the nw negev dunefield is connected to cold event windy climates that may have intensified east mediterranean cyclonic winter storms cannot explain the late holocene dune mobilizations a conceptual model indicates a connection between late holocene dune mobilization widespread anthropogenic occupation and activity and windiness historic grazing and uprooting shrubs for fuel in the past by nomads and sedentary populations led to decimation of dune stabilizers biogenic soil crusts and vegetation causing dune erodibility and low grade activity short term events of amplified wind power in conjunction with periods of augmented anthropogenic activity that triggered major events of dune mobilization elongation and accretion have been preserved in the dune chronostratigraphy because they were short lived the dune mobilization events corresponding windiness and probable dustiness which were examined affected the northern negev landscape differentially however they cannot be shown to have affected the environment sufficiently to influence the decline of the late byzantine and early islam agricultural establishment this study demonstrates the sensitivity of dunes in arid and semi arid regions to a combination of local and short term fluctuations in windiness at times of widespread grazing anthropogenic activity the results indicate that in similar future scenarios sand mobilization may be similarly retriggered to varying degrees

abrasion derived sediments under intensified winds at the latest pleistocene leading edge of the advancing sinai negev erg abstract quaternary desert loess and sandstone loessite relationships in the geological record raise questions regarding causes and mechanisms of silt formation and accretion in the northern sinai negev desert carbonate terrain only sand abrasion in active erg could have produced the large quantities of quartzo feldspathic silts constituting the late quaternary northwestern negev loess in the continuum of source medium to fine sand of dunes to sink silts in loess the very fine sand is unaccounted for in the record this weakens the sand abrasion model of silt formation as a global process here we demonstrate that as predicted by experiments abrasion by advancing dunes generated large quantities of very fine sand 60 110 m deposited within the dune field and in close proximity downwind this very fine sand was generated 13 11 ka possibly synchronous with the younger dryas under gusty sand dust storms in the southeastern mediterranean and specifically in the northern sinai negev erg these very fine sands were washed down slope and filled small basins blocked by the advancing dunes outside these sampling basins it is difficult to identify these sands as a distinct product we conclude that ergs are mega grinders of sand into very fine sand and silt under windy quaternary and ancient aeolian desert environments

airflow and roughness characteristics over partially vegetated linear dunes in the southwest kalahari desert there is little understanding of the flow field surrounding semi vegetated linear dunes and predictions of dune mobility are hampered by a lack of empirical data concerning windflow in an attempt to characterize the near surface airflow upwind of and over partially vegetated linear dunes in the southwest kalahari desert this study presents measurements of vertical and horizontal wind velocity profiles across cross sectional transects of seven partially vegetated linear dunes vegetation surveys combined with velocity measurements from vertical arrays of cup anemometers placed up to 2 3 m above the ground surface were used to gain information concerning the modification of airflow structure caused by the intrusion of the dunes into the atmospheric boundary layer and to predict the variability of aerodynamic roughness z0 from interdune to crest the results suggest an acceleration of flow up the windward slopes of the dunes and as such the data correspond to classical theory concerning flow over low hills essentially jackson and hunt 1975 principles where the theory is incapable of explaining the airflow structure and acceleration characteristics this is explained in part by the presence of a spatially variable vegetation cover over the dunes the vegetation is important both in terms of the varying aerodynamic roughness z0 and problems concerning the definition of a zero plane displacement d it is considered that any attempts to characterize surface shear stress over the kalahari linear dunes in order to predict sand transport and dune mobility will be hampered by two problems these are the progressively non log linear nature of the velocity profiles over the dunes caused by flow acceleration and the production of thin near surface boundary layers caused by areally variable aerodynamic roughness as a result of the partially vegetated nature of the dunes

sm_nd garnet ages from the uluguru granulite complex of eastern tanzania further evidence for post metamorphic slow cooling in the mozambique belt abstract two samples from the uluguru granulite complex yield garnet sm nd ages of 633 7 and 618 16 ma similar to previously published hornblende 40ar 39ar and k ar ages the similarity of the sm nd to the k ar age suggests that the closure temperature of garnet to nd diffusion is similar to that of hornblende to ar diffusion assuming that published zircon u pb ages of about 700 ma date peak granulite facies metamorphism a mean post metamorphic cooling rate of 2 3 c ma can be calculated for the time interval 700 to 630 ma such slow cooling rates imply thermal relaxation with a thickness length scale greater than the thickness of average continental crust this in turn implies that the thermal perturbation responsible for metamorphism was preceded by regional crustal thickening probably in a collisional orogen

patterns of river width and surface area revealed by the satellite derived north american river width data set as hydraulic hydrologic and biogeochemical models evolve toward greater spatial resolution and larger extent robust morphometric data sets are essential to constrain their results here we present the landsat derived north american river width narwidth data set the first fine resolution continental scale river centerline and width database narwidth contains measurements of 2 4 105 km of rivers wider than 30 m at mean annual discharge we find that conventional digital elevation model derived width data sets underestimate the abundance of wide rivers to calculate the total surface area of north american rivers we extrapolate the strong observed relationship between river width and total surface area at different river widths r2 0 99 for 100 2000 m widths to narrower rivers and streams we conservatively estimate the total surface area of north american rivers as 1 24 0 15 0 39 105 km2 1 confidence intervals values 20 15 38 greater than previous estimates used to evaluate greenhouse gas efflux from rivers to the atmosphere

sediment flux and airflow on the stoss slope of a barchan dune abstract measurements of sediment flux on the windward slope of an isolated barchan using an array of 30 sand traps provide new data that can constrain models of dune dynamics the data show that at low wind incident speeds flux increases up the dune exponentially whereas at higher wind speeds the increase with distance approaches linearity wind profile measurements conducted at the same time as the flux measurements indicate that although wind speed at a given height increases by 1 2 times from dune toe to brinkline wind shear velocity derived from the profile data decreases up the dune and is in many cases below transport threshold values this demonstrates that conventional wind profiles derived from anemometry on dunes do not measure the part of the boundary layer that is significant for sediment transport

simulating the surface waters of the amazon river basin impacts of new river geomorphic and flow parameterizations this paper describes the impacts of new river geomorphic and flow parameterizations on the simulated surface waters dynamics of the amazon river basin three major improvements to a hydrologic model are presented 1 the river flow velocity equation is expanded to be dependent on river sinuosity and friction in addition to gradient forces 2 equations defining the morphological characteristics of the river such as river height width and bankfull volume are derived from 31 622 measurements of river morphology and applied within the model 3 1 km resolution topographic data from the shuttle radar topography mission srtm are used to provide physically based fractional flooding of grid cells from a statistical representation of sub grid scale floodplain morphology the discharge and floodplain inundation of the amazon river is simulated for the period 1968 1998 validated against observations and compared with results from a previous version of the model these modifications result in considerable improvement in the simulations of the hydrological features of the amazon river system the major impact is that the average wet season flooded area on the amazon mainstem for the period 1983 1988 is now within 5 of satellite derived estimates of flooded area whereas the previous model overestimates the flooded area by about 80 the improvements are a consequence of the new empirical river geomorphologic functions and the srtm topography the new formulation of the flow velocity equation results in increased river velocity on the mainstem and major tributaries and a better correlation between the mean monthly simulated and observed discharge copyright 2007 john wiley sons ltd

p t t development of archaean granulites in varpaisjarvi central finland ii dating of high grade metamorphism with the u pb and sm nd methods exposed blocks of lower crustal archaean granulites separated by palaeoproterozoic faults occur near the western boundary of the karelian craton in central finland the southwesternmost granulite block in the study area the jonsa block differs from other granulites by having younger zircon u pb and sm nd tdm model ages the u pb ages on zircons and monazites from leucosomes and mesosomes of mafic and pelitic granulites in the jonsa block are ca 2 63 ga which is interpreted as the age of granulite metamorphism igneous enderbites which make up a considerable part of the bedrock in granulite blocks are ca 50 ma older outside the jonsa block both conventional and ion probe zircon ages of mesosomes of migmatitic mafic granulites are 3 2 3 1 ga which are the protolith ages sm nd tdm model ages of the mafic granulites are 2 7 2 9 ga in the jonsa block but ca 3 2 ga in the other granulites the age differences are interpreted to represent terrane accretion that juxtaposed 3 2 ga rocks next to younger rocks all granulites were metamorphosed in similar pt conditions at 2 63 ga granulite metamorphism affected the whole area but was not able to reset zircons in older rocks in all blocks the sm nd garnet whole rock ages are younger ranging from 2 48 2 59 ga this reflects relatively low closure temperature of the sm nd system in garnet in these rocks the u pb age of a palaeoproterozoic dolerite which cuts the granulites is 2 3 ga close to the k ar age of amphibole in a retrogressed fracture

runoff generation in a sandy area the nizzana sands western negev israel this paper presents the results of sprinkling experiments conducted over the lower part of vegetated and crusted linear dunes as well as over flat playa surfaces that appear in the interdune corridors data obtained show that these two surface units respond quickly to rainstorms runoff generation can be expected for any storm exceeding 2 3 mm and runoff coefficients are high when the topsoil algal crust 1 to 2 mm thick is removed from the surface of the dune infiltration increases drastically and eliminates any possibility of runoff generation under present day rainfall conditions this data may be of great help in the understanding of the geomorphology and sedimentary sequence of the corridors separting linear dunes

nature and timing of anatexis in the eastern and southern adirondack highlands metapelitic rocks in the eastern and southern adirondack highlands contain two feldspar quartz leuco somes that pre date most deformational fabric as well as granulite facies recrystallization whole rock xrf analyses of these leucosomes yield cipw norms which correspond closely with experimental melts in the system ab or qt an h 2 o thus indicating that the leucosomes are anatectic in origin derived p t values for anatexis indicate high temperatures and low pressures suggestive of widespread contact metamorphism the heat source is believed to have been provided by anorthositic gabbroic magmas postulated to have been anorogenically emplaced prior to the grenville orogeny

the role of streamline curvature in sand dune dynamics evidence from field and wind tunnel measurements abstract field measurements on an unvegetated 10 m high barchan dune in oman are compared with measurements over a 1 200 scale fixed model in a wind tunnel both the field and wind tunnel data demonstrate similar patterns of wind and shear velocity over the dune confirming significant flow deceleration upwind of and at the toe of the dune acceleration of flow up the windward slope and deceleration between the crest and brink this pattern including the widely reported upwind reduction in shear velocity reflects observations of previous studies such a reduction in shear velocity upwind of the dune should result in a reduction in sand transport and subsequent sand deposition this is not observed in the field wind tunnel modelling using a near surface pulse wire probe suggests that the field method of shear velocity derivation is inadequate the wind tunnel results exhibit no reduction in shear velocity upwind of or at the toe of the dune evidence provided by reynolds stress profiles and turbulence intensities measured in the wind tunnel suggest that this maintenance of upwind shear stress may be a result of concave unstable streamline curvature these additional surface stresses are not recorded by the techniques used in the field measurements using the occurrence of streamline curvature as a starting point a new 2 d model of dune dynamics is deduced this model relies on the establishment of an equilibrium between windward slope morphology surface stresses induced by streamline curvature and streamwise acceleration adopting the criteria that concave streamline curvature and streamwise acceleration both increase surface shear stress whereas convex streamline curvature and deceleration have the opposite effect the relationships between form and process are investigated in each of three morphologically distinct zones the upwind interdune and concave toe region of the dune the convex portion of the windward slope and the crest brink region the applicability of the model is supported by measurements of the rate of sand transport and the change of the dune surface in the field

development of a global 90m water body map using multi temporal landsat images abstract this paper describes the development of a global 3 arc second water body map g3wbm using an automated algorithm to process multi temporal landsat images from the global land survey gls database we used 33 890 scenes from 4 gls epochs in order to delineate a seamless water body map without cloud and ice snow gaps permanent water bodies were distinguished from temporal water covered areas by calculating the frequency of water body existence from overlapping multi temporal landsat scenes by analyzing the frequency of water body existence at 3 arc second resolution the g3wbm separates river channels and floodplains more clearly than previous studies this suggests that the use of multi temporal images is as important as analysis at a higher resolution for global water body mapping the global totals of delineated permanent water body area and temporal water covered area are 3 25 and 0 49 million km2 respectively which highlights the importance of river floodplain separation using multi temporal images the accuracy of the water body classification was validated in hokkaido japan and in the contiguous united states using an existing water body databases there was almost no commission error and about 70 of lakes 1 km2 shows relative water area error

a subgrid channel model for simulating river hydraulics and floodplain inundation over large and data sparse areas 1 this paper presents a new computationally efficient hydraulic model for simulating the spatially distributed dynamics of water surface elevation wave speed and inundation extent over large data sparse domains the numerical scheme is based on an extension of the hydraulic model lisflood fp to include a subgrid scale representation of channelized flows which allows river channels with any width below that of the grid resolution to be simulated the scheme is shown to be numerically stable and scalable before being applied to an 800 km reach of the river niger in mali the niger application focused on the performance of four different model structures a model without channels two dimensional 2 d model a model without a floodplain one dimensional 1 d model a model of the main channels and floodplain 1 d 2 d model and the subgrid approach developed here inclusion of both the channel network and the floodplain was shown to be essential meaning that large scale models of this region including routing models for land surface schemes will require a floodplain component including subgrid scale channels on the floodplain changed inundation dynamics over the delta significantly and increased simulation accuracy in terms of water level wave propagation speed and inundation extent furthermore only the subgrid model showed a consistent parameterization when calibrated against either gauge or icesat water level data suggesting that connectivity provided by small channels is a strong control on the hydraulics of the floodplain or at the very least that low resolution gridded hydraulic models require additional connectivity to represent the delta flow dynamics

improving the tandem x digital elevation model for flood modelling using flood extents from synthetic aperture radar images abstract the topography of many floodplains in the developed world has now been surveyed with high resolution sensors such as airborne lidar light detection and ranging giving accurate digital elevation models dems that facilitate accurate flood inundation modelling this is not always the case for remote rivers in developing countries however the accuracy of dems produced for modelling studies on such rivers should be enhanced in the near future by the high resolution tandem x worlddem in a parallel development increasing use is now being made of flood extents derived from high resolution synthetic aperture radar sar images for calibrating validating and assimilating observations into flood inundation models in order to improve these this paper discusses an additional use of sar flood extents namely to improve the accuracy of the tandem x dem in the floodplain covered by the flood extents thereby permanently improving this dem for future flood modelling and other studies the method is based on the fact that for larger rivers the water elevation generally changes only slowly along a reach so that the boundary of the flood extent the waterline can be regarded locally as a quasi contour as a result heights of adjacent pixels along a small section of waterline can be regarded as samples with a common population mean the height of the central pixel in the section can be replaced with the average of these heights leading to a more accurate estimate while this will result in a reduction in the height errors along a waterline the waterline is a linear feature in a two dimensional space however improvements to the dem heights between adjacent pairs of waterlines can also be made because dem heights enclosed by the higher waterline of a pair must be at least no higher than the corrected heights along the higher waterline whereas dem heights not enclosed by the lower waterline must in general be no lower than the corrected heights along the lower waterline in addition dem heights between the higher and lower waterlines can also be assigned smaller errors because of the reduced errors on the corrected waterline heights the method was tested on a section of the tandem x intermediate dem idem covering an 11 km reach of the warwickshire avon england flood extents from four cosmo skymed images were available at various stages of a flood in november 2012 and a lidar dem was available for validation in the area covered by the flood extents the original idem heights had a mean difference from the corresponding lidar heights of 0 5 m with a standard deviation of 2 0 m while the corrected heights had a mean difference of 0 3 m with standard deviation 1 2 m these figures show that significant reductions in idem height bias and error can be made using the method with the corrected error being only 60 of the original even if only a single sar image obtained near the peak of the flood was used the corrected error was only 66 of the original the method should also be capable of improving the final tandem x dem and other dems and may also be of use with data from the swot surface water and ocean topography satellite

riverscape mapping with helicopter based structure from motion photogrammetry abstract recent developments in the remote sensing of fluvial systems have provided researchers with unprecedented views on the complexity of rivers an aerial perspective is key to mapping and understanding the river at a variety of spatial scales i employed a helicopter mounted digital slr camera and structure from motion sfm photogrammetry to bridge the gap between smaller scale aerial surveys from platforms like small unmanned aerial systems and larger scale commercial aerial photography or airborne lidar collections this low cost solution produced high spatial resolution aerial photography and digital elevation models for a 32 km segment of the middle fork john day river in east central oregon using these data i extracted channel morphology data at 3 m intervals downstream and took an inductive approach to evaluating the controls on channel morphology and the human influences on the river using a combination of segment scale and hyperscale analyses the sfm process produced 10 cm pixel orthophotographs and dems with submeter horizontal accuracy but the dems suffered from a systematic distortion that resulted from the parallel camera geometry of the flight plan the riverscape has been affected by human actions such as mining cattle grazing and restoration however differentiating a human signal from the natural patterns of channel morphology was difficult the hyperscale analysis provided insight into several interesting downstream patterns in channel morphology that with further analysis could provide explanations on the physical controls of channel morphology overall sfm has the potential to be a powerful low cost addition to the fluvial remote sensing toolkit

near channel versus watershed controls on sediment rating curves predicting riverine suspended sediment flux is a fundamental problem in geomorphology with important implications for water quality land and water resource management and aquatic ecosystem health to advance understanding we evaluated environmental and landscape factors that influence sediment rating curves srcs we generated srcs with recent total suspended solids tsss and discharge data from 45 gages on 36 rivers throughout the state of minnesota usa watersheds range from 32 to 14 600 km2 and represent distinct settings regarding topography land cover and geologic history rivers exhibited three distinct src shapes simple power functions threshold power functions and peaked or negative slope functions we computed src exponents and coefficients describing the steepness of the relation and the tss concentration at median flows respectively in addition to quantifying watershed topography climate hydrology geology soil type and land cover we used lidar topography to characterize the near channel environment upstream of gages we used random forest models to analyze relations between src parameters and attributes of the watershed and the near channel environment the models correctly classify 78 of src shapes and explain 37 60 of variance in src parameters we find that src steepness exponent is strongly related to near channel morphological characteristics including near channel relief channel gradient and presence of lakes along the local channel network but not to land use in contrast land use influences tss concentrations at moderate and low flow these findings suggest that the near channel environment controls changes in tss as flows increase whereas land use drives median and low flow tss conditions

conditions of archean granulite metamorphism in the godthab fiskenaesset region southern west greenland the nordlandet peninsula akia terrane and the tasiusarsuaq terrane in southern west greenland were metamorphosed to granulite facies at 3 0 and 2 8 ga respectively temperatures of metamorphism are estimated using magnetite ilmenite garnet orthopyroxene garnet clinopyroxene and garnet biotite thermometers barometry has been carried out in the two terranes using eight different garnet barometers a uniform set of activity models for all minerals including the garnet activity model of newton et al 1986 is applied to each barometer in order to permit comparison pressure estimates using the different barometers are generally quite consistent 1 5 kbar use of the newton et al 1986 garnet activity data results in pressures similar to those obtained using other garnet activity models peak metamorphic conditions on the nordlandet peninsula are estimated to have been 800 50 c 7 9 1 0 kbar values of logfo2 are estimated to have been 1 1 to 2 0 above the quartz magnetite fayalite buffer from assemblages of magnetite ilmenite and quartz magnetite ferrosilite peak metamorphic conditions in the tasiusarsuaq terrane are estimated to have been 780 50 c 8 9 1 0 kbar estimates of fh2o and fco2 using biotite amphibile grossular anorthite and grossular scapolite equilibria are low in both terranes these results suggest that granulite metamorphism was fluid absent in both terranes and that the metamorphism in the akia terrane and possibly also in the tasiusarsuaq terrane was initiated by the injection of large volumes of magma into the lower crust