structural outline of a tertiary basement cored uplift inversion structure in western spitsbergen svalbard kinematics and controlling factors the tertiary fold and thrust belt of spitsbergen can be divided into a western basement involved fold thrust stack and a central eastern foreland fold and thrust belt in western nordenskiold land the first order structure is an ene verging basement cored fold and fault complex involving paleozoic to tertiary strata the northern part reveals an upright monocline geometry of east tilted sedimentary cover units with associated layer parallel to low angle thrusts and folds these structures consist of two populations oriented both parallel to nnw sse and oblique to wnw ese the general structural trend of the fold complex in the central and southern parts of west nordenskiold land the fold complex involves tilted basement cut by steep transverse faults and late normal faults the east limb of the fold complex displays repeated basement and paleozoic strata orustdalen formation in its core and mesozoic triassic strata influenced by map scale chevron folds and two decollement levels all located above an eastward rotated major detachment fault the kleivdalen thrust establishing fold fault relations includes a three stage structural history in the fold complex as follows 1 a phase of early nne ssw shortening associated with wnw ese folds and thrusts and 2 a dominant ene wsw basement involved shortening leading to the first order nnw sse striking fold complex followed by 3 approximately e w extension the resulting structures and structural variability along strike as well as across strike appear to have been controlled by basement and carboniferous basin structures underlying the permian cretaceous platform strata restored stratigraphic sections based on thrust repetition of basement and cover e g within a type section of the carboniferous orustdalen formation support such an interpretation a tentative inversion tectonic model reproduces the position s of local and major thrust ramps and associated folds as a result of inheritance from carboniferous basin structures

regionally differentiated contribution of mountain glaciers and ice caps to future sea level rise the contribution to sea level rise from mountain glaciers and ice caps has grown over the past decades a projection of their melting during the twenty first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21 of their total global volume

dating of late paleozoic rifting events in the north atlantic new biostratigraphic data from the uppermost devonian and carboniferous of east greenland the uppermost devonian and carboniferous sedimentary rocks in east greenland include eight spore pollen assemblages of early tournaisian tn1 to mid visean v3 and westphalian age the recognition of these assemblages provides the first firmly established biostratigraphic scheme of these sedimentary rocks and dates the earliest phase of late paleozoic extensional tectonics in east greenland as pre tournaisian the latest rift pulse of the paleozoic started in the westphalian and new half graben systems continued to develop along the basin margins until autunian time this new age information suggests that late paleozoic rifting events were synchronous in the entire north atlantic arctic region

first permo carboniferous conodonts from north greenland upper palaeozoic conodonts are described for the first time from the north greenland wandel sea basin in eastern peary land the moscovian species idiognathodus incurvus and the kasimovian gzhelian i magnificus occur in the upper carboniferous foldedal formation while an assemblage from the lower part of the succeeding kim fjelde formation suggests deposition in the upper artinskian neostreptognathodus pequopensis n clarki zone these datings confirm the existence in the northern part of the wandel sea basin of the pronounced early permian hiatus previously recognized in holm land and amdrup land in the southern part of the basin the single conodont specimen found at prinsesse ingeborg halvo further corrobates the local absence of this regional hiatus in the central part of the wandel sea basin

ce anomalies in the lew85300 eucrite evidence for ree mobilization during antarctic weathering abstract there is abundant evidence for widespread ree mobilization in antarctic eucrites resulting in ce and eu anomalies and lower whole rock ree abundances relative to typical eucrites using secondary ion mass spectrometry sims we investigated the microdistribution of ce anomalies in the antarctic polymict eucrite lew85300 ce anomalies positive and or negative are present in all three of the minerals plagioclase pyroxene and silica analysed the anomalies occur in grains from all four clasts as well as in mineral and lithic fragments from the surrounding matrix thus there appears to be no lithologic association silica which has been heavily shocked and altered exhibits a lree enriched pattern with negative ce and eu anomalies consistent with a derivation of the ree from ca phosphate dissolution trivalent ree are leached from the phosphates with preferential retention of tetravalent ce and redeposited on silica pyroxene is also widely affected by ree mobilization due to an extensive shock induced microcrack network along cleavage planes a tendency for the largest ce anomalies to occur at low lree concentrations suggests that pyroxene itself experienced ree leaching with concomitant ce retention ce anomalies are rare in plagioclase because this mineral lacks an extensive network along which ree can be mobilized the widespread ree mobilization and evidence for other forms of weathering requires that trace element data be used cautiously especially for antarctic eucrites

the yermak plateau in the arctic ocean in the light of reflection seismic data implication for its tectonic and sedimentary evolution summary the separation of northeast greenland and svalbard is the result of large scale strike slip movements during cenozoic times geological evidence for these movements can be found onshore both on north greenland and svalbard however the role of the submarine yermak plateau yp in this process is unclear the compilation of available multichannel reflection and wide angle seismic data give new insights into the sedimentary and crustal structure and evolution of the plateau the flat surface of the present day plateau is a quite young feature up to 2 km of cenozoic sediments cover a rough basement which show similarities to the rough topography and strike of geological structures of spitsbergen island in some basins more than 4 km of sedimentary rocks could be mapped the most pronounced structure is the sverdrup bank which appears to be part of a larger crustal block p wave velocities of about 4 5 km s 1 derived from sonobuoy data indicate that its uppermost part is most probably composed of sedimentary or volcanic rocks we have made a correlation of previously defined seismic units across the yp to outline the history of sediment deposition in the area the existing graben structures on the plateau might have provided early shallow pathways for water exchange between the arctic and the atlantic oceans a chaotic sedimentary apron east of the sverdrup bank and bright reflections near the mosby seamount interpreted as magmatic sills suggest tectonic and magmatic events during the miocene

vertical distribution of trace elements in laterite soil suriname abstract the vertical distribution of 20 elements in a 12 5 m thick laterite profile from suriname south america has been investigated using neutron activation analysis atomic absorption spectrometry and x ray fluorescence the mineralogical composition was quantitatively determined from calculations based on results from x ray diffraction thermal gravimetric methods and from the data obtained for major elements using x ray fluorescence the most characteristic change observed in the mineralogy with depth is the increase in kaolinite relative to gibbsite a considerable fractionation with depth is found for different trace elements the enrichment of the lanthanoids la and ce at 3 4 m below surface and of sm and eu at 10 12 5 m depth demonstrates that the distribution of elements despite the similarity in chemical properties is seriously affected by weathering processes the laterite soil samples were also separated in al and fe rich fractions using naoh these separation experiments demonstrated that the trace elements are mainly associated with the fe rich red mud fraction of the laterite soil

chemical processes affecting the mobility of major minor and trace elements during weathering of granitic rocks abstract the behaviour of 38 major and trace elements as well as changes in the mineralogy have been examined in 10 weathering profiles developing on some portuguese granitic rocks element mobilities are calculated from geochemical data normalized with respect to ti in the fresh parent rock chemical elements are divided into two groups immobile and mobile on the basis of their geochemical distribution during weathering elements that are immobile during weathering are zr hf fe al th nb sc and the ree very mobile are ca na p k sr ba rb mg and si mobile elements are derived mainly from leachable minerals such as feldspars micas and apatites whereas immobile elements are either concentrated in resistate phases or strongly adsorbed by secondary minerals the geochemical behaviour of mn cr v fe and ce is very dependent on redox conditions redox transformations of these elements can be used to set limits on the oxidation state of a weathering suite the ree are mobilized or fractionated during late stages of weathering but not during moderate stages of weathering this fractionation is caused by selective leaching of rocks composed of both stable and unstable minerals containing ree

model for late mesozoic early tertiary tectonics of coastal california and western mexico and speculations on the origin of the san andreas fault cretaceous and early tertiary arc and forearc rocks found along the coast in southern california and baja california have been shown by paleomagnetic measurements to have originated many hundreds or even several thousands of kilometers south of their current locations northward transport also is found in cretaceous batholithic rocks near the edge of the continent in washington and british columbia the consistency of this pattern suggests that slices of arc and forearc rock originating on the western edge of north america have been translated along the coast by strike slip faulting strike slip faults are shown to be an expected response to north oblique subduction of the farallon and or kula plates faulting and subduction probably were concurrent activities i e the arc and forearc grew and were displaced simultaneously because displacement was dominantly parallel to subduction related lithic belts arc and forearc rocks may have traveled large distances without producing either significant hiatuses in the rock record or conspicuous disruptions in the distribution of lithic belts subduction related strike slip faulting is shown to be favored by high angles of oblique convergence shallow dip of the subducting slab relatively easy slip on potential faults within the arc or forearc and the existence of a place for the moving sliver to go it is suggested that these conditions are not difficult to satisfy and that subduction related strike slip faulting may thus be a common feature of convergent orogens the location of the san andreas fault inboard from the continental margin may be attributable to localization of the pacific north american transform by a system of precollision subduction related faults

the margin between senja and spitsbergen fracture zones implications from plate tectonics abstract analysis of multichannel seismic data from the continental margin off svalbard between the senja and spitsbergen fracture zones suggests that the transition between continental and oceanic crust is located at or close to the hornsund fault zone in the late paleocene early eoeene 57 m y the region between svalbard and northeast greenland was subjected to regional shear movements associated with a transform system between the young lofoten greenland basin and the arctic ocean approximately 50 m y ago the spreading axis migrated to the northeast creating a deep basin north of the greenland senja fracture zone forming the passive margin between bear island and 76 5 n north of 76 5 n the regional transform was maintained at the time of the main reorganization of relative plate motion 36 m y the northern margin evolved a continental fragment was possibly cut off from the svalbard margin forming a small microcontinent the microcontinent appears as the submarine ridge which has been associated with the hovgaard fracture zone it is suggested that the sediments west of the hornsund fault zone are not older than eocene in the south and mid oligocene in the north the position of the spreading axis has greatly influenced the margin sedimentation

a comparative study of gabbro and granite weathering in the piedmont of the southeastern u s a gabbros and granites weather in quite different fashions granites develop extensive weathering rind systems 2 m thick in which plagioclase is altered to a gibbsite kaolinite assemblage in rindlets adjacent to the fresh rock contact in the outer rindlets the clay fraction is dominated by kaolinite and dioctahedral vermiculite not surprisingly granitic weathering rind systems display relative depletions of si na ca rb and sr and relative enrichments of sesquioxides in contrast gabbro weathering rind systems are characterized by many thin 1 cm rindlets whose alteration products are dominated by limonitization of ferromagnesian minerals apart from a decrease in feofe2o3 ratios in the outer rindlets there is little relative depletion or enrichment of major elements in gabbro weathering rinds as compared to their fresh rock cores this contradiction in goldich s stability series is explained if weathering rinds are produced faster on gabbros than in granite outcrops thus the low degree of mineral alteration in gabbro rindlets reflects a shorter time of residence for minerals in this system compared to rindlets on granitic outcrops biotite and perthitic microcline were separated from a fresh granite and its attendant weathering rind system during alteration the albitic blebs of the perthite are dissolved leaving no trace of residual clay the result is a porous microcline whose composition is equivalent to the microcline matrix in the unweathered perthite progressive alteration of biotite results in oxidation of octahedrally coordinated fe2 with concomitant loss of k this results in the formation of dioctahedral vermiculites in outer rindlet samples of granite

petrogenetic and mineralization processes in paleo to mesoproterozoic rapakivi granites examples from pitinga and goias brazil abstract the 1 8 ga pitinga granites agua boa and madeira massifs in amazonas northern brazil are within plate shallow level rapakivi granites associated with an extensional fracture system they comprise an early facies of pyterlitic to wiborgitic rapakivi granite a fine to medium grained biotite granite as well as topaz granite agua boa massif and albite granite madeira massif the granites are usually metaluminous to peraluminous the albite granite however is peralkaline they are enriched in sio2 k2o na2o f rb th nb y zr and the rare earth element ree and impoverished in mgo tio2 p2o5 and sr as the majority of sn mineralized granites sn contents range from 1 ppm in the rapakivi facies to 3400 ppm in the albite granite end at 1 8 ga values vary from 2 2 to 0 4 and nd model ages lie between 2 4 and 2 1 ga mineralization in the madeira massif includes disseminated magmatic cryolite zircon cassiterite pyrochlore columbite tantalite and xenotime and massive cryolite bodies in the f rich peralkaline albite granite in the agua boa massif sn mineralization is associated with greisens and episyenite the 1 77 ga g1 and 1 58 1 57 ga g2 rapakivi granites of goias central brazil are coeval with the arai rift basin granites of the g1 suite are metaluminous and alkaline while the g2 suite is metaluminous to peraluminous both are enriched in f sn rb y th nb ga and the ree primary micas range from fe rich biotite to zinnwaldite the micas of the more evolved granites and the metasomatic micas are strongly enriched in f with f li between 2 and 10 the initial end values of both suites show a considerable range 14 to 0 and indicate substantial compositional variation in source sn deposits in goias are hosted mainly by greisens indium is concentrated in quartz topaz rock and albitized g2d granite of the mangabeira massif and is always related to a cassiterite sulfide association this quartz topaz rock is of metasomatic origin probably generated by a hydrothermal fluid derived from the topaz albite granite mineralization in the studied deposits was essentially associated with f enrichment in the peralkaline madeira albite granite extremely high f contents favored disseminated mineralization while in the goias tin province gtp and agua boa massif greisenization was related to early fluid saturation the gtp and pitinga granites display tectonic petrogenetic geochemical isotopic and metallogenic similarities that can be applied in search of sn and rare metal deposits

along strike changes in fault array and rift basin geometry of the carboniferous billefjorden trough svalbard norway abstract the billefjorden fault zone bfz of svalbard norway is a long lived major tectonic lineament with significant influence on the structural style of the northwestern barents shelf the fault zone can be traced for around 2 300 km in an n s direction where it is made up of three major fault strands all dipping 50 70 to the east field and seismic data delineate gradual shifts in displacement between master faults northern odelfjellet balliolbreen and southern dronbreen faults and suggest that two c 20 km long 2 3 km wide relay zones exist along strike the western fault strand consistently has a pre carboniferous reverse character placing basement on top of devonian sedimentary units with a throw estimated at 10 km subsequent carboniferous extensional reactivation of segments of the bfz resulted in formation of the billefjorden trough with a rift basin showing a fairly consistent polarity for its length this suggests a profound control by the older devonian reverse faults on the extensional structural style the billefjorden trough extends for a minimum of 110 km along strike and is 20 30 km wide at the most a gentle north plunge of the basin axis in the south is mirrored by an opposite plunge in the north offering a depth thickness of around 2000 m in the central realm diminishing to 500 m in the south geometries of the trough suggest sedimentary response to fault growth with weak lithologies such as evaporites promoting fault monocline formation and associated lenticular basin geometries on the contrary wedged shaped fill geometries toward major faults is consistent with significant fault movement and growth sequences subsequent mild tertiary reactivation of fault segments of the bfz is suggested by local reverse faults and deep seated anticline syncline pairs

chemical evolution of rare earth elements fractionation between colloidal and solution phases of filtered river water abstract within the dissolved fraction of connecticut river water there is large scale fractionation of rare earth elements between colloidal and solution phases colloidal particles carry a large part of the dissolved ree pool filtration through filters with progressively smaller pore size 0 45 0 22 and 0 025 m results in filtrates with lower absolute concentrations of ree and more fractionated compositions with decreasing pore size the filtrates have shale normalized abundances which become systematically more depleted in the lree relative to the hree hence both the solution and colloidal phases are significantly fractionated with respect to the dissolved fraction these conclusions are consistent with previous studies of ree in rivers estuaries and soils and with surface solution speciation models colloids play an important role in the aquatic geochemistry of rare earth elements they are responsible for the fractionation of ree during the estuarine removal of ree the removal of suspended and colloidal particles from river water leaves the solution phase of river water with compositions of ree as evolved as those of surface seawater hence the evolution of the composition of ree in river water and seawater is significantly influenced by colloid formation during chemical weathering on the continents

late cenozoic geomorphic evolution in response to inversion evidence from field and gpr studies in kim drainage basin western india abstract this study presents field and ground penetrating radar gpr data for understanding geomorphic evolution of the kim drainage basin in response to tectonic inversion of the narmada ankleshwar block of the cambay rift basin located on the western continental margin of india the narmada ankleshwar block underwent continuous sedimentation up to mio pliocene and subsequently was subjected to compressional inversion four geomorphic surfaces are recognised that formed in response to the varying degrees of tectonic activity related to phases of inversion these are the early pleistocene erosional surface epes late pleistocene depositional surface lpds early holocene erosional surface ehes and the late holocene depositional surface lhds the phases of increased tectonic activity relate to two erosional episodes while two depositional periods relate to waning tectonic activity or quiescent periods we show that the narmada ankleshwar block suffered inversion earlier than other parts of the cambay basin to the north of the nsf localisation of early inversion movements occurred in an area characterised by thinner crust and involved the development of new reverse faults and transformation of the nsf from a normal to a reverse fault gpr studies indicate the reverse nature of the various faults in the kim drainage basin and provide evidence of their late reactivation under compression the study demonstrates that the parts of a large sedimentary basin can undergo inversion at different times depending on the orientation of pre existing crustal discontinuities with respect to the controlling stress trajectories

tertiary tectonism and basin inversion of the st jonsfjorden region svalbard abstract deformed basement and cover rocks of the st jonsfjorden area further define the character of spitsbergen s tertiary fold and thrust belt three major thrusts comprise a folded ca n060 e directed foreland propagating thust stack with likely additional subsurface thrust faults the folded vegardbreen robertsonfjellet thrust is the most significant fault in the complex and re emerges in the core of a disrupted synclinal structure in triassic strata shortening across the area indicated from line length restoration is of the order of 13 km differences in stratigraphy between and within thrust sheets indicate the thrust stack initiated along the edge of a westward deepening carbonbiferous basin with a fault step margin and represents basin inversion early structures related to basin formation had a major control on later thrust sheet evolution and the complexity of inversion structures reflects the initial complexity of the basin geometry such basin inversion could characterize the length of the fold and thrust belt the st jonsfjorden structures are primarily contractional and together with areas farther southeast in the fold thrust belt indicate shortening took place perpendicular to the fold belt across much of the length of the evolving margin

tertiary or cretaceous age for spitsbergen s fold thrust belt on the barents shelf several publications propose that main phase fold thrust development on spitsbergen was late cretaceous and not tertiary as previously thought the question of timing is crucial to models for crustal response to transpressive plate motions involvement of tertiary strata in fold thrust structures the sedimentology of the tertiary basin strata and studies of paleo stress field evolution all indicate paleocene to eocene fold thrust development during opening of the norwegian greenland oceanic basin a regional angular unconformity of 1 between paleocene and early cretaceous strata is consistently disconformable to the eye and precludes any significant older deformation in the immediate area pre unconformity deformation was likely strike slip in character and concentrated in the west the proposal for late cretaceous fold thrust belt formation is inconsistent with the geology

rare earth elements in river waters we measured rare earth element ree concentrations in river waters to characterize the suspended and dissolved river flux of the ree to the oceans the ree pattern of river suspended materials is sensitive to drainage basin geology a positive correlation is observed between la yb ratios and nd model ages for the rivers studied major rivers have light ree enriched patterns relative to the north american shale composite nasc with la yb n 1 6 2 7 river water dissolved material 0 2 m is heavy ree enriched relative to suspended material and the most pronounced negative ce anomalies occur in rivers of high ph light ree concentrations vary by approximately 3 orders of magnitude and are inversely related to ph and major cation concentrations from these data we estimate that typical major river runoff has heavy ree depleted suspended material with la yb n 1 9 we conclude that the terrigenous input to the oceans from major rivers is heavy ree depleted relative to shales from the available data average river water dissolved material appears to be heavy ree enriched with la yb n 0 4 estuarine removal processes lower the dissolved ree river flux by approximately 60 and result in a flux that is more heavy ree enriched with la yb n 0 2 calculated oceanic residence times with respect to river input range from 2300 to 21 000 years are shortest for ce and greatest for the heavy ree and la such long residence times may suggest the presence of additional sources of ree in seawater

structural evolution of a frontal ramp section of the west spitsbergen tertiary fold and thrust belt north of isfjorden spitsbergen the geometry and kinematic evolution of a frontal ramp section associated with the tertiary west spitsbergen orogenic belt has been investigated in a small area lappdalen north of isfjorden the previously recognized thrust front corresponds to a complex step or ramp in the position of the sole thrust in the area the sole thrust is localized to the evaporites of the permian gipshuken formation to the west of the footwall ramp whereas to the east it continues as a bedding parallel thrust in triassic shales sassendalen group the area to the west of the footwall ramp is characterized by large scale thrusts and folds involving the permian gipshuken and kapp starostin formations and the lower part of the triassic sassendalen group east of the footwall ramp both permian and triassic strata are sub horizontal and apparently undeformed three major thrust sheets are recognized based on the geometric relationship between folds and faults in the area both fault bend and fault propogation mechanisms of folding are inferred restoration of the kapp starostin formation to its pre deformational state indicates a minimum of 35 shortening structural observations within the sassendalen group in the study area and on dickson land suggest that some of this shortening is transmitted eastwards along one or more bedding parallel thrusts in the sassendalen group

temperature and precipitation climate at the equilibrium line altitude of glaciers expressed by the degree day factor for melting snow several authors relate accumulation or precipitation at the glacier equilibrium line altitude ela to summer mean temperature using exponential or power law functions i analyze the accumulation temperature relation at the ela with a degree day model using data from the 1992 paper by a ohmura and others the dataset includes estimates at the ela of winter balance and of winter balance plus summer precipitation which represent respectively low and high estimates of annual accumulation which is seldom measured the ohmura dataset only lists summer mean temperature but i recover monthly temperatures for the whole year for 66 of the glaciers by assuming sinusoidal temperature variation through the year and using annual temperature range from a gridded climatology monthly degree day sums are then estimated from monthly mean temperature and summed to give annual totals so degree day factors for melting snow at the ela are obtained the degree day factors fall close to those reported in the literature for glacier snowmelt with averages of 3 5 1 4 and 4 6 1 4 mm d 1 k 1 for low and high accumulation estimates on the 66 glaciers the degree day model gives a family of accumulation temperature curves that depend upon the annual temperature range representing the contrast between maritime and continental climates

erratum to magmatism and eurekan deformation in the high arctic large igneous province 40ar 39ar age of kap washington group volcanics north greenland earth planet sci lett 303 2011 203 214

greenland fracture zone east greenland ridge s revisited indications of a c22 change in plate motion 1 changes in the lithospheric stress field causing axial rift migration and reorientation of the transform are generally proposed as an explanation for anomalously old crust and or major aseismic valleys in oceanic ridge transform ridge settings similarly transform migration of the greenland fracture zone and separation of the 200 km long fracture zone parallel continental east greenland ridge from the eurasia plate is thought to be related to a major change in relative plate motions between greenland and eurasia during the earliest oligocene chron 13 time this study presents a reinterpretation of the greenland fracture zone east greenland ridge based on new and existing geophysical data evidence is shown for two overstepping ridge segments segments a and b of which segment a corresponds to the already known east greenland ridge while segment b was not detected previously interpretation of sonobuoy data and revised modeling of existing obs data across segment b indicate a continental composition of the segment this interpretation is supported by magnetic anomaly data the segments a and b are bounded by portions of the greenland fracture zone with a distinct 10 difference in strike this is suggested to relate to an early episode of transform migration and reorientation of the lithospheric stress field around chron 22 time i e shortly after the eocene breakup in the northern ne atlantic these findings contradict with previous interpretations of the fracture zone which infer simple pre c13 strike slip kinematics

pre break up palaeostress state along the east greenland margin this paper describes intraplate deformation and the palaeostress state along the east greenland margin during the paleocene between 65 and 55 myr ago prior to the onset of the ne atlantic spreading it is shown that the pre break up deformation is the result of dip oblique strike slip tectonics in the se and compressive tectonics in the north the reduced palaeostress tensors derived from inversion of the fault slip data show that the maximum horizontal stress 1 is compressive and the orientations of 1 change from ene wsw in the south to nne ssw in the north the reconstructed palaeostress trajectory map demonstrates that the 1 orientations reflect the plate motion path and define small circles whereas the trends of the minimum horizontal stress 3 converge and cluster around an area in the arctic that is interpreted as the rotation pole of greenland the intraplate deformation folding and uplift that affected the greenland and european margins the barents sea and the north sea during the paleocene can be explained by the counter clockwise rotation of greenland the present paper calculates the pole of rotation of greenland using the kinematics of brittle faults along the plate margin and the palaeostress derived from inversion of fault slip data analysis as an indicator of motion path

concentration of rare earth elements in the faixa placha tin deposit pedra branca a type granitic massif central brazil and its potential for ion adsorption type ree y mineralization abstract the goias tin province gtp in brazil has great potential for rare earth elements ree deposits associated with a type granites such as the pedra branca massif which contains several sn deposits and ree anomalies hosted in its cupola and fracture greisens the faixa placha is the most important tin deposit in the pedra branca massif and has high ree y concentrations both in the sn ore and parent biotite granite as well as greisenized granites and greisens with the potential to be economically used as a byproduct of tin the values exceed 1000 ppm in light rare earth elements lrees and 500 ppm in heavy rare earth elements hrees y in the parent granite ree concentrations in greisenized granites and greisens are similar to that of the parent granite indicating that the enrichment in ree is due to the presence of ree bearing primary minerals and that greisenization did not affect the original magmatic primary ree content the ree bearing minerals in the parent granite are allanite monazite xenotime thorite apatite and zircon these minerals except zircon are altered to secondary monazite silicates fluorcarbonates and oxyfluorides which are responsible for the concentration of ree in greisenized granites and greisens and the availability of these metals for the clay fraction of saprolites and soils ion exchange analyses in the saprolites and soils of a faixa placha profile show that the extractions in the clay fraction are more enriched in ree y compared to the whole soil extractions with values between 3425 and 36 762 ppm and between 2804 and 21 689 ppm respectively the rees are more enriched in the basal part of the profile especially the lrees these exchangeable ree y concentrations indicate the potential of the faixa placha and nearby areas to constitute an important ree y deposit of the ion adsorption type

asymmetric geophysical signatures in the greenland norwegian and southern labrador seas and the eurasia basin a thorough examination of geophysical data from the greenland norwegian sea eurasia basin and southern labrador sea shows significant asymmetry of several parameters basement topography adjusted for sediment loading free air gravity anomaly spreading half rate and seismicity with respect to crustal age 1 1 average zero age depth 0 57 m y b p depth of highest rift mountain summits and depth to magnetic basement 10 30 km from axis of mohns and knipovich ridges is less on the north american plate flanks the zero age depth asymmetry is 400 500 m for the eurasia basin 0 57 m y b p and for mohns ridge 57 22 m y b p and 150 200 m for younger mohns ridge crust 22 0 m y b p and for the extinct aegir ridge 57 27 m y b p there is little or no asymmetry in the labrador sea except near the extinct rift valley where the east flank is 150 300 m shallower magnetic depth to source computations provide an independent confirmation of basement asymmetry the belts 10 30 km from the axis of mohns and knipovich ridges are 100 150 m shallower on the west flank of these ridges the shallower ridge flank is topographically rougher so that average rift mountain summits are 300 m shallower on the west flanks of the mohns knipovich ridges a larger asymmetry than for average zero age depth the amount of topographic asymmetry is greatest near the mohns knipovich bend asymmetry appears to be greatest for ridges oriented normal to the spreading direction and less for oblique spreading 2 2 free air gravity anomaly asymmetries of 5 to 20 mgal sign indicates west flank is more positive are associated with topographic asymmetry at least within 10 15 m y of the axis of mohns and knipovich ridges gravity is reduced on the older flanks west of the extinct mid labrador ridge and east of mohns ridge asymmetric crustal layer thicknesses or densities provide one possible explanation although deep seated sources e g mantle convection unrelated to the crust cannot be excluded 3 3 spreading half rate was about 5 15 lower on the north american plate flanks of mohns ridge 57 35 m y and in the eurasia basin 0 57 m y thus the fast spreading flank tends to produce deeper smoother crust however topographic asymmetry cannot relate only to spreading rate asymmetry since for the young mohns ridge crust 9 m y b p faster spreading and higher topography are both associated with the west flank 4 4 mid plate seismicity is higher on the eurasia eastern flank of mohns and knipovich ridge but this effect may be unrelated to the other three the fluid dynamical model of stein et al correctly explains the sense of spreading rate asymmetry the north american plate moving faster over mantle is growing more slowly however the other asymmetries and their causal relationships remain theoretically unexplained

a shallow detachment beneath the north greenland fold belt implications for sedimentation and tectonics in northern greenland in early palaeozoic time a turbidite trough the eastward extension of the hazen trough of arctic canada was flanked to the south by a carbonate platform the trough was deformed during the mid palaeozoic ellesmerian orogeny to form the e w trending north greenland fold belt this fold belt was deformed further by eurekan tertiary structures important among which is a major fault complex the harder fjord fault zone hffz the suggestion has been made that this fault zone controlled early cambrian sedimentation even though the fault trace does not coincide with the trough platform facies transition in sediments of that age this has led to some controversy we report new information from a mapping programme by the geological survey of greenland which has established the thin skinned nature of ellesmerian deformation at the trough platform transition and implies that much of the fold belt is underlain by a shallow detachment this in turn implies that the hffz exists in the hanging wall of the detachment while the early cambrian trough platform transition is located autochthonously in the foot wall we adduce evidence to show that the latter was probably controlled by syndepositional faulting with actively eroding fault scarps and suggest that these basement structures were reactivated in a dextral strike slip mode in early tertiary time to form the hffz as now observed

the effects of weathering on rare earth element y and ba abundances in tertiary basalts from southeastern australia tholeiitic basalts showing anomalously high ba y and rare earth element ree concentrations occur within the tertiary newer volcanic province of victoria and these geochemical characteristics are related to incipient alteration accompanying weathering ree and y released during weathering of basalts are retained either in secondary phosphate or clay minerals and in rocks showing very high ba concentrations the ba is present as baso4 leaching experiments suggest that glassy or fine grained rocks are more likely to release ree y and ba while more extensively altered rocks are likely to hold these elements probably because they substitute in or are adsorbed on clay minerals or because secondary baso4 and ree phosphates are resistant to acid leaching samples taken sequentially across a weathering profile in a tholeiitic basalt flow from fresh to intensively altered rock illustrate that in the very earliest stages of alteration extreme variations in the abundances of ba y and ree can occur this is reflected in the broad patterns of trace element behaviour manifested by an extensive analysed sample suite from the victorian newer volcanic province where there is no correlation between anomalous enrichments in ba y or ree and the level of incipient alteration ba anomalies are not necessarily accompanied by abnormal y and ree behaviour and this is probably because the mobility of each trace element is a function of a the ionic radius and charge of the ionic species it forms in solution b local groundwater parameters such as eh ph groundwater flux and concentrations in the groundwater of species such as so42 and c the secondary mineral assemblages developed in a particular situation sr isotopic compositions are not strongly affected by incipient weathering and do not show significant changes until alteration has progressed to the point where plagioclase begins to break down the study illustrates that relatively slight alteration at the earliest stages of weathering can produce drastic changes in the concentrations of ree y and ba and petrographic assessment of the freshness of samples is not precise enough to eliminate prior to analysis cases where these effects may be manifested where weathering has caused changes in abundance patterns these may be recognised by careful comparisons of appropriate elemental ratios e g ba rb throughout a particular analysed sample suite

eurekan transpressive deformation in the wandel hav mobile belt northeast greenland 1 besides the w e trending kap cannon thrust zone and harder fjord fault zone the 300 km long and nw se striking wandel hav mobile belt represents the third major fault zone in north greenland structural analyses in several areas of this belt suggest that compressive deformation is characterized by transpressive dextral strike slip kinematics this is demonstrated by a combination of folding around w e axes approximately north and south directed reverse faulting and dextral strike slip displacements along nw se trending fault lines the initial formation of the long linear faults is interpreted to be related to deformational events in late paleozoic triassic jurassic and late cretaceous times due to the lack of structural evidence we assume that deformations led to the generation of extension faults which probably were reactivated during dextral strike slip tectonism it is suggested that dextral transpressive deformation was coeval with n s compression at the harder fjord fault zone and cap cannon thrust zone and took place during eocene eurekan times dextral strike slip tectonism in the wandel hav mobile belt was the result of n s compression due to a general northward movement of the greenland plate as a zone of crustal weakness the belt can be interpreted as the onshore equivalent of the main transcurrent fault zone de geer fault which caused the intracontinental dextral slip of svalbard barents shelf relative to north greenland during early tertiary eurekan times and prior to their separation in this configuration it represents one part of the belt of eurekan deformation which extends from the canadian arctic islands over north greenland to the barents shelf where compressive deformation is recorded in the west spitsbergen fold and thrust belt

low sea level rise projections from mountain glaciers and icecaps under global warming the mean sea level has been projected to rise in the 21st century as a result of global warming such projections of sea level change depend on estimated future greenhouse emissions and on differing models but model average results from a mid range scenario a1b suggests a 0 387 m rise by 2100 refs 1 2 the largest contributions to sea level rise are estimated to come from thermal expansion 0 288 m and the melting of mountain glaciers and icecaps 0 106 m with smaller inputs from greenland 0 024 m and antarctica 0 074 m here we apply a melt model and a geometric volume model to our lower estimate of ice volume and assess the contribution of glaciers to sea level rise excluding those in greenland and antarctica we provide the first separate assessment of melt contributions from mountain glaciers and icecaps as well as an improved treatment of volume shrinkage we find that icecaps melt more slowly than mountain glaciers whose area declines rapidly in the 21st century making glaciers a limiting source for ice melt using two climate models we project sea level rise due to melting of mountain glaciers and icecaps to be 0 046 and 0 051 m by 2100 about half that of previous projections

global glacier mass changes and their contributions to sea level rise from 1961 to 2016 glaciers distinct from the greenland and antarctic ice sheets cover an area of approximately 706 000 square kilometres globally1 with an estimated total volume of 170 000 cubic kilometres or 0 4 metres of potential sea level rise equivalent2 retreating and thinning glaciers are icons of climate change3 and affect regional runoff4 as well as global sea level5 6 in past reports from the intergovernmental panel on climate change estimates of changes in glacier mass were based on the multiplication of averaged or interpolated results from available observations of a few hundred glaciers by defined regional glacier areas7 10 for data scarce regions these results had to be complemented with estimates based on satellite altimetry and gravimetry11 these past approaches were challenged by the small number and heterogeneous spatiotemporal distribution of in situ measurement series and their often unknown ability to represent their respective mountain ranges as well as by the spatial limitations of satellite altimetry for which only point data are available and gravimetry with its coarse resolution here we use an extrapolation of glaciological and geodetic observations to show that glaciers contributed 27 22 millimetres to global mean sea level rise from 1961 to 2016 regional specific mass change rates for 2006 2016 range from 0 1 metres to 1 2 metres of water equivalent per year resulting in a global sea level contribution of 335 144 gigatonnes or 0 92 0 39 millimetres per year although statistical uncertainty ranges overlap our conclusions suggest that glacier mass loss may be larger than previously reported11 the present glacier mass loss is equivalent to the sea level contribution of the greenland ice sheet12 clearly exceeds the loss from the antarctic ice sheet13 and accounts for 25 to 30 per cent of the total observed sea level rise14 present mass loss rates indicate that glaciers could almost disappear in some mountain ranges in this century while heavily glacierized regions will continue to contribute to sea level rise beyond 2100 the largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea level rise from 1961 to 2016 at rates of ice loss that could see the disappearance of many glaciers this century

late palaeozoic evolution of the north atlantic margin of pangea abstract eleven palaeogeographic maps spanning the earliest carboniferous tournaisian to late permian kazanian have been constructed for the northern north atlantic based on available onshore and offshore data each palaeogeographic map corresponds to an epoch i e 4 17 ma there are no reconstructions of the serpukhovian and tatarian and the kungurian ufimian are treated as one the palaeogeographic reconstructions outline a change in the overall depositional environment of the barents sea north greenland area from huge humid flood plains in the early carboniferous over shallow warm seas in the mid carboniferous to mid permian to cooler and possibly deeper marine environments in the late permian in east greenland non marine conditions occurred during the entire carboniferous and following a prolonged early permian hiatus warm water carbonates were deposited during the late permian the changes reflect large scale shifts in palaeoclimatic and subsidence patterns related to the northward drift of the area and ongoing rifting in the region

geochemical and mineralogical characteristics of ion adsorption type ree mineralization in phuket thailand geochemical and mineralogical studies were conducted on the 12 m thick weathering profile of the kata beach granite in phuket thailand in order to reveal the transport and adsorption of rare earth elements ree related to the ion adsorption type mineralization the parent rock is ilmenite series biotite granite with transitional characteristics from i type to s type abundant in ree 592 ppm ree are contained dominantly in fluorocarbonate as well as in allanite titanite apatite and zircon the chondrite normalized ree pattern of the parent granite indicates enrichment of lree relative to hree and no significant ce anomaly the upper part of the weathering profile from the surface to 4 5 m depth is mostly characterized by positive ce anomaly showing lower ree contents ranging from 174 to 548 ppm and lower percentages of adsorbed ree from 34 to 68 compared with the parent granite in contrast the lower part of the profile from 4 5 to 12 m depth is characterized by negative ce anomaly showing higher ree contents ranging from 578 to 1 084 ppm and higher percentages from 53 to 85 the negative ce anomaly and enrichment of ree in the lower part of the profile suggest that acidic soil water in an oxidizing condition in the upper part mostly immobilized ce4 as ceo2 and transported ree3 downward to the lower part of the profile the transported ree3 were adsorbed onto weathering products or distributed to secondary minerals such as rhabdophane the immobilization of ree results from the increase of ph due to the contact with higher ph groundwater since the majority of ree in the weathered granite are present in the ion adsorption fraction with negative ce anomaly the percentages of adsorbed ree are positively correlated with the whole rock negative ce anomaly the result of this study suggests that the ion adsorption type ree mineralization is identified by the occurrence of easily soluble ree fluorocarbonate and whole rock negative ce anomaly of weathered granite although fractionation of ree in weathered granite is controlled by the occurrence of ree bearing minerals and adsorption by weathering products the ion adsorption fraction tends to be enriched in lree relative to weathered granite

a spatially resolved estimate of high mountain asia glacier mass balances from 2000 to 2016 glacier mass balances in high mountain asia are uncertain satellite stereo imagery allows a spatially resolved estimate for about 92 of the glacierized area and yields a region wide average of about 16 gt yr 1 for 2000 to 2016

the eurekan deformation in the arctic an outline the evolution of the eurekan deformation zones in the arctic is closely related to the development of the circum greenland plate boundaries in early cenozoic times 53 34 ma mostly the eurekan orogeny or deformation has been interpreted as a predominantly compressive tectonic event but the eurekan deformational history in the arctic was not the result of a single tectonic episode it rather represents a complex sequence of successive tectonic stages which produced a number of intra continental deformation zones with changing sometimes opposing lateral oblique and convergent kinematics in the canadian arctic archipelago north and ne greenland and svalbard the interaction between the continental plates especially in combination with the development of transform faults resulted onshore in the formation of several complex deformation zones and areas of eurekan deformation the eurekan deformation can be divided into two major tectonic stages the first phase in the early eocene was dominated by orthogonal compression in the west spitsbergen fold and thrust belt along the west margin of the barents shelf and contemporaneous sinistral strike slip tectonics along the wegener fault and on ellesmere island whereas the second phase in the late eocene was characterized by dextral strike slip and compression on ellesmere island and contemporaneous dextral transpression and transtension along the de geer fracture zone or hornsund fault complex between ne greenland and spitsbergen

kinematics of tertiary deformation in the basement involved fold thrust complex western nordenskiold land svalbard tectonic implications based on fault slip data analysis abstract kinematic analysis based on the interpretation of small scale fault and fold data supports a kinematic evolution history involving heterogeneous crustal shortening and uplift and subsequent extension collapse for the major west coast fold thrust complex in western nordenskiold land svalbard this deformation can be divided into three main kinematic events stage 1 represents an early distinctive nne ssw oriented contractional episode that generated layer parallel and low angle thrusts and internal folds stage 1 structures population 1 are arranged in an apparent en echelon geometry and oblique direction relative to the major nne ssw trending fold thrust complex of stage 2 affinity stage 2 structures include ene verging chevron folds and steeply wsw dipping thrusts and duplexes that evolved during a progressive wsw ene oriented contractional episode initial pre fold stratal shortening stage 2a was followed by a continuous buildup of the fold thrust complex and general crustal thickening syn fold stage 2b until a supercritical height thickness was reached post fold stage 2c at this stage a change in the stress field caused failure of the fold thrust complex and continued ne sw directed shortening was accommodated as vertical strike slip faults population 2c late w e to wsw ene directed extension the stage 3 episode was probably related to collapse of the overthickened stage 2 fold thrust complex the detailed reconstruction of kinematic events in western nordenskiold land supports initial breakup of the greenland svalbard area in early paleocene times during dextral nne ssw directed transpression stage 1 the major deformational episode stage 2 probably of mid paleocene to eocene age was characterized by progressive wsw ene directed shortening and was related to decoupled deformation where broad zones of convergent strain were linked to narrow strike slip zones this strain partitioning is considered to have begun when the hornsund fault zone widened into and reactivated the basin bounding faults of the carboniferous st jonsfjorden trough the latest kinematic episode stage 3 is likely of eocene age and may be ascribed to extensional collapse in the hinterland of the western spitsbergen orogenic wedge within a regional dextral transpressive setting

solid liquid ree fractionation in the lateritic system of goyoum east cameroon the implication for the present dynamics of the soil covers of the humid tropical regions the ree th weathering geochemistry and mineralogy has been investigated in a lateritic soil cover in relation to the close hydrographical system at goyoum east cameroon the stutied area composed of gneissic hills covered by humid tropical forest belongs to the sanaga river basin and corresponds to a transition vegetation zone between rainforest and savannah a representative soil catena was taken as a reference zone close to the sanaga river the gneissic parent rock soil and groundwater samples have been cut off in pits in the lower part of the catena waters were also sampled both in brooks rich in organic matter and in the sanaga river all the waters were sampled seasonally during the rainy and dry periods the water rock interactions and the exportation of ree and th have been discussed as a function of the evolution of specific ratios considering th as the less mobile element during laterization variation of parent rock pr normalized ratios ln th pr vs depth show that the upper ferruginous horizons are depleted in ree while the basal saprolite presents accumulation zones which are differently located for ce and the other lrees the hrees are also depleted the la accumulations are located near the saprolite gneiss weathering front associated with negative ce anomalies ce ce 0 4 the ce accumulations inducing strong positive ce anomalies ce ce 4 are located in the upper saprolite beneath the ferruginous horizons all along the soil catena the secondary lree bearing minerals which reflect lree fractionation during incipient weathering of the gneiss are hydrous phosphates rhabdophane lreepo4 nh2o and cerianite ceo2 whose precipitation depends on the eh ph changes in the soil profiles on the other hand hree depletion is controlled by the dissolution of xenotime the major hree bearer in the parent gneiss in the 0 45 m filtered acidic groundwater ph 5 5 which have flooded the saprolite for a long residence time th contents are extremely low 0 th 10 ppt while lree contents are high 90 la 450 ppt in these filtered waters th seems to be strongly controlled by minerals i e thorianite which lead to its immobilization in the soil while lree remain in the soluble and or colloidal pools moreover the groundwaters show significant negative ce anomalies throughout the year 0 1 ce ce 0 4 the mobilization of lree except redox active ce results from the dissolution and or the mobilization in colloidal form of the secondary phosphates which may present major negative ce anomalies as indicated by the bulk soil analyses at the saprolite gneiss weathering front therefore the groundwaters have the signature of saprolitic materials we propose that the strong positive ce anomalies of the upper saprolite result from ancient weathering processes these processes would have led to much stronger ce iii ce iv dissolution reprecipitation conditions than those occurring at the present time in the saprolite in the 0 45 m filtered brook acidic blackwaters lree and th contents are high 100 th 400 ppt 400 la 1700 ppt in this organic matter rich environment lree and th are highly mobilized the colloial pool controls half of the whole lree th load the geochemical signature of these waters is independent of the gneissic parent rock and soil lree contents there is no ce anomaly this signature is similar to those of other organic rich rivers draining humid tropical ecosystems in the world in the 0 45 m filtered sanaga waters lree and th contents are lower than in the brooks 15 th 40 ppt 40 la 300 ppt these concentrations are dependent on the time and on the colloidal composition however 90 of these elements are mainly controlled by the suspended pool

u pb zircon geochronology of precambrian tin bearing continental type acid magmatism in central brazil abstract u pb geochronological data for alkali rich granitic and associated rhyolitic rocks from two different tin bearing sub provinces of the goias tin province in central brazil reveal two distinct episodes of mid proterozoic continental acid magmatism at ca 1770 ma and 1600 ma ago u pb zircon data for the sucuri and soledade granites of the eastern rio parana sub province rps define upper intercept ages of 1767 10 ma and 1769 2 ma respectively these ages are indistinguishable from a u pb age of a rhyolite from the basal portion of the arai group 1771 2 ma these results attest to the contemporaneity of the intrusion of the granites and the crystallization of the rhyolitic lavas in the rio parana sub province u pb isotopic results from zircons from the serra da mesa granite in the western rio tocantins sub province rts indicate that the granitic igneous activity in that area is ca 150 ma younger than that in the rps the inheritance pattern observed in the zircons from the arai rhyolite suggests that the sialic basement in the rps region may include an early proterozoic ca 2 2 ga component inheritance of possibly archaean age was also found in zircons from the sucuri granite lower intercept age of 658 ma for the soledade granite zircons indicate pb loss during the late proterozoic brasiliano pan african thermo tectonic event 650 550 ma similar associations of tin bearing alkali rich granites with rhyolites and succeeding continental sediments are known in other parts of the precambrian shield of brazil this indicates that extensive areas of this shield experienced extensional tectonics in intracontinental settings between ca 1700 and 1900 ma ago

the permian sn metallogenic event and its geodynamic setting in east kunlun nw china evidence from zircon and cassiterite geochronology geochemistry and sr nd hf isotopes of the xiaowolong skarn sn deposit abstract abundant granitoids are exposed along the east kunlun orogenic belt ekob and many skarn deposits occur at the contacts between intrusions and strata one such is the xiaowolong deposit a skarn type tin polymetallic deposit that is temporally and spatially associated with porphyry monzogranite tin mineralization is mainly hosted by the skarn in this study we reported zircon and cassiterite u pb ages whole rock geochemistry and sr nd hf isotopic data and used these to constrain the timing of intrusion and mineralization in the xiaowolong deposit and identify the origin of the ore related granites and the link between sn mineralization and granitic magmatism age determinations by la icp ms u pb zircon dating indicated that the porphyry monzogranite formed at 260 0 0 7 ma cassiterite from the ore bearing skarn yielded a tera wasserburg u pb lower intercept age of 258 0 3 7 ma these ages suggested that both granitic intrusion and related sn mineralization in the xiaowolong deposit were initiated during the permian ca 260 ma the porphyry monzogranites had high sio2 71 26 73 13 wt and al2o3 13 84 14 46 wt contents were alkali enriched k2o na2o 7 08 7 69 wt had a cnk values that ranged from 1 01 to 1 05 were enriched in light rees and large ion lithophile elements such as rb th u and k were depleted in high field strength elements and had relatively low zr nb y and ce contents they thus exhibited the geochemical characteristics of i type granite the porphyry monzogranite had consistent negative whole rock nd t 6 8 to 7 1 and magmatic zircon hf t values ranging from 7 4 to 1 6 and two stage hf model ages ranging from 1393 ma to 1758 ma detailed elemental and isotopic data demonstrated that the porphyry monzogranite were derived from partial melting of ancient crustal source and emplacement in a subduction tectonic setting the xiaowolong tin mineralization event indicated that the ekob has great potential for exploration focusing on permian triassic sn skarn deposits

glaciermip a model intercomparison of global scale glacier mass balance models and projections global scale 21st century glacier mass change projections from six published global glacier models are systematically compared as part of the glacier model intercomparison project in total 214 pro

new data on the age of the uppermost ors and the lowermost post ors strata in dickson land spitsbergen and implications for the age of the svalbardian deformation

tertiary west spitsbergen fold and thrust belt on broggerhalvoya svalbard structural evolution and kinematics the tertiary fold and thrust belt on broggerhalvoya is characterized by a ne vergent pile of nine thrust sheets the basal sole thrust of the pile is located in precambrian phyllites and climbs up section to the ne the lower thrust sheets consist predominantly of post caledonian cover sediments two thrust sheets in the central part of the pile contain a syncline and anticline on a kilometer scale the kilometer scale fold is cut by juxtaposed thrusts giving rise to the formation of four structurally higher basement dominated thrust sheets a five stage kinematic model is proposed 1 in sequence foreland propagating formation of the lower thrust sheets with ramp flat geometries in response to n s subhorizontal bedding parallel movements 2 change in tectonic transport to more east northeasterly directions and first out of sequence thrusting inversion and uplift of the basement in the hinterland formation of the kilometer scale fold structure 3 truncation of the kilometer scale fold by a thrust fault and stacking of the highest basement dominated thrust sheets by hindward propagating mode of thrust generation 4 n s extension due to extensional collaps of the stack 5 w e extension the strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheet reflecting a temporal change to a more transpressive regime ramping of some thrust faults is suggested to be in part controlled by reactivated carboniferous normal faults the basal sole thrust of the thrust sheet stack also follows the trend of the kongsvegen fault which showed enhanced activity during late mesozoic early tertiary extension the curvature of the west spitsbergen fold and thrust belt on broggerhalvoya is interpreted to be controlled mainly by oblique ramping on the kongsvegen fault associated with pinning on the nordfjorden block as well as by along strike lithological and thickness variations of the post caledonian strata in addition this suggests that pre existing structures have controlled the tertiary geometry the temporal change in the kinematics during thrust tectonics can be linked with the plate tectonic framework in the arctic during tertiary times

seismic stratigraphy of the post breakup succession offshore northeast greenland links to margin uplift abstract the timing of the continental breakup between norway and greenland and the subsequent plate tectonic motions are well understood however due to the remote location of the northeast greenland shelf relatively few details about the tectonosedimentary response to the tectonism following the breakup have previously been published this article gives new insights into the structural and sedimentary history of the northeast greenland shelf with an emphasis on the post breakup tectonics using state of the art 2d seismic data the results of this study clearly shows a highly dynamic post breakup tectonic setting with pronounced kilometre scale fault offsets tilting of the danmarkshavn basin and pronounced progradational events the tectonosedimentary events are linked with the passage of the icelandic mantle plume south of the northeast greenland shelf based on tectonostratigraphic interpretations and integration of data from odp 913 this study constructs a temporally robust model for the post breakup succession significant post breakup uplift and tectonism related to thermal uplift is present on the margin it is observed that the icelandic hot spot passes relatively close by the northeast greenland shelf

tectonic evolution of the west spitsbergen fold belt abstract the west spitsbergen fold belt has a complex tectonic history which is recorded in a thick nearly complete upper proterozoic phanerozoic layered sequence work since 1977 near bellsund allows recognition of the main deformational events in that segment of the fold belt the strata are grouped informally into the metamorphosed hecla hoek hh sequence proterozoic and the van keulenfjorden vk sequence carboniferous cretaceous separated by a pronounced unconformity the hh is divided into the antoniabreen succession the chamberlindalen succession and the kapp lyell tillite the first two consist of diverse clastic and carbonate rocks along with some volcanic rocks the vk is a platform sequence of shallow marine and terrestrial sedimentary rocks these layered rocks are intruded by a few mesozoic dolerite sills and dikes subhorizontal paleogene sedimentary rocks are preserved in a small graben both layered sequences have undergone strong deformation structures mainly caledonian age in the hh can be grouped as phase 1 small isoclinal folds subhorizontal axial planar foliation ridge groove lineation in the foliation and large recumbent folds phase 2 tight to isoclinal folds axial planar foliation and younger weak folds and foliations kink bands crinkles structures mainly tertiary age in the vk include faults thrust reverse down to the east bedding plane normal other normal folds symmetric asymmetric overturned recumbent isoclinal and foliation in some tightly folded triassic shales six deformational events can be identified here each described below in terms of age intensity and kinematic pattern d1 vendian or early paleozoic very strong nnw sse shortening nnw transport d2 early paleozoic pre carboniferous strong ne sw shortening ne vergence d3 middle carboniferous moderate unclear limited exposure d4 early cretaceous weak extension direction unclear d5 early tertiary very strong locally uplift in w ene wsw shortening ene translation d6 middle tertiary moderate ne sw extension

tectonic inversion in the wandel sea basin a new structural model of kilen eastern north greenland the seminunatak kilen in eastern north greenland with its complexly deformed carboniferous cretaceous strata is a key area to understand the tectonic history of the transform plate boundary between eastern north greenland and svalbard detailed 3 d geological mapping from oblique photogrammetry along with limited ground fieldwork and interpretation of previously published data forms the basis for a new structural model of kilen previous structural models interpreted rhombic shaped fault patterns as the evidence for strike slip tectonics these structures are here interpreted to be the result of a post coniacian ne sw extension with nw se trending normal faults followed by later n s compression of presumable paleocene eocene age folding the faults passively and suggesting the presence of a basal detachment furthermore two thrust sheets have been distinguished on kilen a lower kilen thrust sheet and an upper hondal elv thrust sheet separated by a subhorizontal fault the central detachment the style of deformation and the structures described are interpreted as the result of paleocene eocene n s directed compression resulting in basin inversion with strike slip faults only having minor status this indicates that the greenland margin as exposed on kilen and the conjugate svalbard margin in the west spitsbergen fold and thrust belt are more similar than previously anticipated

major element ree and other trace element behavior in amphibolite weathering under semiarid conditions in southern india abstract a body of komatiitic amphibolite an enclave within the archean high grade orthogneisses in southern india shows mild chemical weathering under semiarid conditions along fractures chemical weathering has advanced chemical index of alteration documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont declaretextfontcommand textcyr cyr pagestyle empty declaremathsizes 10 9 7 6 begin document landscape mathrm cia 53 end document cia of fresh documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage

wandel sea basin a new synthesis of the late paleozoic to tertiary accumulation in north greenland the wandel sea basin in eastern north greenland is the least known of the onshore depositional centers associated with the formation of the arctic and north atlantic oceans whereas the main features of svalbard and the sverdrup basin have been known for many years it has only recently been possible to investigate the wandel sea basin in any detail in the course of recent investigations the concept of a classic bull9s eye type of accumulation in north greenland has become increasingly difficult to maintain this paper presents an alternative model involving a complex series of events with an overall change from elongate rift basins to a strike slip dominated structural belt individual events in this development provide evidence of early steps in the extended processes leading up to ocean formation

distributed ice thickness and volume of all glaciers around the globe 1 a new physically based approach for calculating glacier ice thickness distribution and volume is presented and applied to all glaciers and ice caps worldwide combining glacier outlines of the globally complete randolph glacier inventory with terrain elevation models shuttle radar topography mission advanced spaceborne thermal emission and reflection radiometer we use a simple dynamic model to obtain spatially distributed thickness of individual glaciers by inverting their surface topography results are validated against a comprehensive set of thickness observations for 300 glaciers from most glacierized regions of the world for all mountain glaciers and ice caps outside of the antarctic and greenland ice sheets we find a total ice volume of 170 103 21 103 km3 or 0 43 0 06 m of potential sea level rise

svartfjella eidembukta and daudmannsodden lineament tertiary orogen parallel motion in the crystalline hinterland of spitsbergen s fold thrust belt within metamorphic basement rocks of the hinterland of spitsbergen s tertiary fold thrust belt a 35 km long zone of notably deformed carboniferous strata and cretaceous intrusives forms a major orogen parallel lineament from svartfjella to eidembukta to daudmannsodden sedl orientations and geometries of map scale fault duplexes and associated fault plane striae populations of folds and associated cleavage and of tension gashes all indicate orogen parallel motion occurred along the sedl structural analyses indicates three phases 1 ene directed overthrusting 2 sinistral motion with a backthrust component and 3 dextral strike slip motion this history indicates a change from orogen perpendicular to orogen parallel movements orogen parallel movement was likely coeval with orogen perpendicular fold thrust transport to the ene in the foreland a model where dextral transpressive motion between greenland and svalbard was decoupled explains the hinterland foreland difference basement fabric aligned with carboniferous carbonates on the steep foreland face of an antiformal stack provided a through going weak surface a prerequisite for decoupling sinistral orogen parallel motion is explicable by short lived episode of sinistral plate motion or by local wedge extrusion during dextral transpression the evolution of decoupling patterns has significant implications for deducing plate motions from local kinematic and paleostress studies

thrust tectonics on broggerhalvoya and their relationship to the tertiary west spitsbergen fold and thrust belt the tertiary fold and thrust belt on broggerhalvoya is characterized by a ne vergent pile of nine thrust sheets the sole thrust of the pile is located in precambrian phyllites and climbs up section to the northeast four lower thrust sheets consisting predominantly of upper palaeozoic sediments are overlain by two thrust sheets in the central part of the stack which contain a kilometre scale syncline and anticline the fold is cut by juxtaposed thrusts giving rise to the formation of three structurally higher basement dominated thrust sheets a multiple stage kinematic model is proposed including 1 in sequence foreland propagating formation of the lower thrust sheets in response to n s subhorizontal bedding parallel movements 2 a change in tectonic transport to ene and out of sequence thrusting and formation of the kilometre scale fold structure followed by 3 truncation of the kilometre scale fold and stacking of the highest basement dominated thrust sheets by hind ward propagating out of sequence thrusting the strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheets reflecting a temporal change to a more transpressive regime thrusting was followed by 4 n s extension and 5 w e extension comparison of the structural geometry and kinematic evolution of broggerhalvoya with the data reported for the fold belt further south allows us to assume a coeval evolution with the fold belt a latest paleocene early eocene age for the main phase of thrusting is suggested for the west spitsbergen fold and thrust belt the main phases therefore pre date the separation of svalbard and greenland due to right lateral movements along the hornsund fault zone the fold belt s temporal evolution followed by the formation of the forlandsundet graben can be linked with the plate kinematic framework in the span between latest paleocene and middle eocene times

short paper nares strait was not a cenozoic plate boundary nares strait the linear seaway between greenland and arctic canada has long been regarded as a palaeogene plate boundary along which major transform movement accommodated opening of the labrador sea fieldwork however revealed several stratigraphic markers which cross the strait and precle substantial displacement current plate reconstructions based on geophysical data continue to invoke major convergence and strike slip along the strait the manner in which palaeozoic structural trends curve into parallelism with the strait as they cross it has been used to support this idea restoration of the trends gives an apparent 200 km offset along the strait the curvature is an original tectonic feature and cannot be restored stratigraphic data preclude substantial cenozoic displacement along or across nares strait reconstructions based on indirect geophysical evidence which violate the geology must be wrong

rare earth element mobility during conversion of nepheline syenite into lateritic bauxite at passa quatro minais gerais brazil abstract in a lateritic bauxite formed by weathering of nepheline syenite at passa quatro minas gerais state brazil bauxites on the hill tops directly develop from the syenite bed rock while downslope a kaolinitic layer occurs between bauxite and synetie a petrological investigation was performed on undisturbed weathered rock samples collected from a representative upslope pit the undisturbed weathered rocks were chemically analysed for major trace elements including ree and zr mass balance calculations were applied and the behaviour of the ree in the passa quatro weathering system was established compared to ree reference chondrite and to ree reference parent rock in the lateritic bauxite the results suggest that the first stages of weathering induce a volumetric change of 50 i e collapse with respect to the parent rock and remove ree with a slightly larger loss of the lree except ce compared to the hree in the upper layers where bauxite is more mature a net mass gain in ree is observed relative to the underlying layers this gain takes place during the reduction of the upper layer during the downward progression of the weathering front very significant ree losses occurs during the bauxitization processes throughout the upslope profile in addition the downslope kaolinitic system is demonstrated to be depleted in ree in the same proportions as the upslope bauxite we proposed that the ree exported in solution from the whole weathering mantle have enriched neighbouring watershed sediments

the origin of the west spitsbergen fold belt from geological constraints and plate kinematics implications for the arctic abstract the west spitsbergen fold belt which extends for 300 km along the western margin of svalbard and is up to 80 km wide has much in common with foreland fold and thrust belts the near foreland segment of the fold belt exhibits ramp flat thrust trajectories whilst structurally higher nappes are typified by more listric thrusts higher nappes to the west contain imbricated carboniferous and basement rocks showing that the latter were actively involved in the fold belt deformation and a minimum of 80 km total shortening perpendicular to the western margin of svalbard is estimated the early stages of the eurekan deformation in north greenland can be linked to that of the west spitsbergen fold belt and the combined shortening across the two fold belts may exceed 80 km in ellesmere island eurekan structures are distributed in an arc like belt which records between 50 to 100 km of shortening since the late cretaceous kinematic reconstructions suggest that before the opening of the eurasian basin and norwegian greenland sea chron 25 svalbard was linked to north america in the late cretaceous palaeocene interval the motion across the greenland svalbard margin was mainly convergent giving rise to the west spitsbergen fold belt and the eurekan structures of north greenland the dextral separation of greenland and svalbard in post chron 24 time was accompanied by extension followed by pure extension in post chron 13 time

a detailed assessment of global rare earth element resources opportunities and challenges rare earth elements ree are indispensable to infrastructure technology and modern lifestyles which has led to an increasing demand for these elements the current global rare earth oxides reo market is dominated by chinese production which peaked in 2006 at 133 000 tonnes reo per year accounting for some 97 1 of global production causing concern about the long term supply of ree resources although the ree consist of 17 individual elements 15 lanthanides plus scandium and yttrium that are hosted by numerous types of mineralization the relatively modest scale of the global ree mining sector has limited our knowledge of ree mineral resources and mineralizing systems compared to metals such as copper and iron which are produced in much larger quantities in order to quantitatively analyze the mineralogy concentrations and geologic types of ree deposits we compiled a global dataset of ree mineral resources based on the most recently available data 2013 2014 this compilation yields minimum global contained total rare earth oxides plus yttrium oxide treo y resources of 619 5 mt split between 267 deposits deposits with available grade and tonnage data 260 of the 267 deposits in our database contain some 88 483 mt of mineral resources at an average concentration of 0 63 treo y hosting 553 7 mt treo y of the 267 total deposits in our database some 160 have mineral resources reported using statutory mining codes e g jorc ni43 101 samrec with the remaining 107 projects having crirsco noncompliant mineral resources that are based on information available in the industry literature and peer reviewed scientific articles approximately 51 4 of global reo resources are hosted by carbonatite deposits and bastnasite monazite and xenotime are the three most significant ree minerals accounting for 90 of the total resources within our database in terms of ree resources by individual country china dominates currently known treo y resources 268 1 mt accounting for 43 of the global reo resources within our database with australia russia canada and brazil having 64 5 62 3 48 3 and 47 1 mt of contained treo y resources respectively some 84 3 mt treo y is hosted within tailings dominated by tailings from bayan obo but with smaller resources at palabora steenkampskraal and mary kathleen and 12 4 mt treo y is hosted by monazite within heavy mineral sands projects illustrating the potential for reo production from resources other than traditional hard rock mining global ree resources are dominated by the light ree having an average light reo lreo la gd to heavy reo tb lu and y ratio of 13 1 these ree deposits contain an average of 81 ppm th and 127 ppm u indicating that radioactive waste associated with ree extraction and refining could be a concern modeling the 2012 global production figures of 110 kt treo y combined with an assumed 5 annual growth in ree demand indicates that known ree resources could sustain production until 2100 and that geologic scarcity is not an immediate problem this suggests that other issues such as environmental economic and social factors will strongly influence the development of ree resources

reactivation history of the long lived billefjorden fault zone in north central spitsbergen svalbard new geological mapping has revealed further details of the tectonic and stratigraphic effects of devonian and later reactivations of the billefjorden fault zone one of a number of important north south trending lineaments in svalbard analysis of offsets along the many steeply dipping faults within the zone and effects on the subsidence and deformation of the adjacent crustal blocks is presented as a series of tectonic maps from the late devonian through to the tertiary late devonian sinistral transpression suggested previously cannot be ruled out and carboniferous reactivation was dominated by extension with possibly a slight dextral strike slip component after late carboniferous to early cretaceous platform subsidence during which the fault zone had little effect on sedimentation development of the tertiary west spitsbergen fold belt related to the opening of the arctic ocean involved compressive and transpressive reactivation of basement seated structures further east including the billefjorden fault zone in the billefjorden austfjorden area this produced a large monoclinal fold across the fault zone which was later cross cut by extensional structures to produce the present day billefjorden syncline this localized late extension is related to a slight variation in the trend of the billefjorden fault zone through this area

a transpressional origin for the west spitsbergen fold and thrust belt insight from analog modeling 1 the west spitsbergen fold and thrust belt formed along the transform plate boundary between greenland and the western barents sea during paleocene eocene breakup in the northern north atlantic approximately 20 40 km margin perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head on collision we have applied scaled analog tectonic modeling to test the former hypothesis a pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15 convergence angle by movement of a basal plate the kinematics was quantified by means of digital particle image velocimetry the result was a doubly vergent transpressional wedge consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike slip zone and an adjacent low taper thin skinned fold and thrust belt the doubly vergent wedge evolved through several kinematic phases three main stages were identified namely 1 initial distributed deformation 2 development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones and finally 3 a stage of full strain partitioning between a central strike slip zone and reverse displacement along marginal shear zones with folding and thrusting in a thin skinned belt on the proside the analog model convincingly reproduced the geometry and the kinematic evolution of the west spitsbergen fold and thrust belt supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement

state of stress and tectonic evolution of the west spitsbergen fold belt abstract the west spitsbergen fold belt is the result of a e w to ene wsw oriented compression which affected the whole of spitsbergen a late cretaceous palaeocene age for the fold belt deformation is indicated by the involvement of only the basal tertiary conglomerates in the folding and thrusting in western spitsbergen this compressional event was followed by a strike slip stress pattern with nw se oriented extension and ne sw compression which generated micro structures within the tertiary rocks on the map scale normal faults produced by a ne sw oriented extension overprint the compressional structures the later strike slip and extensional stress patterns correspond to the svalbard greenland dextral motion along the de geer zone in latest palaeocene eocene time the latest tectonic event which affected the whole of svalbard was an e w oriented extension related to the spreading along the knipovich ridge in oligocene neogene time

geochemical and mineralogical characteristics of reey occurrences in the mocambo granitic massif tin bearing a type granite central brazil and its potential for ion adsorption type reey mineralization abstract the mocambo granitic massif is an a type granite located in the northeastern part of goias state near the city of monte alegre de goias it belongs to the pedra branca suite which is itself part of the goias tin province a group of stanniferous granites that exhibit similar geochemical features including to a greater or lesser degree of rare earth elements enrichment the parent rock in the mocambo granitic massif is a coarse porphyritic pink biotite granite thin section observations coupled with electron microprobe analyses reveal the presence of several ree bearing minerals allanite fergusonite ce fergusonite y zircon and apatite as accessory minerals and xenotime y bastnasite ce thorite monazite ce and hingganite y as secondary hydrothermal minerals fergusonite and hingganite are identified in this massif for the first time this work investigates the forms of occurrence and enrichment of rare earth elements in the mocambo granitic massif in the parent rock as well as in greisen saprolite and soil with emphasis placed on the rare earth elements adsorbed on clay minerals and the entire process of transport and fractionation of these elements from the fresh rock until adsorption the results show enrichment of rare earth elements with the exception of ce in soils in comparison to rock especially in the clay fraction moreover they suggest that these elements are mostly adsorbed on clay minerals mostly kaolinite and illite which are identified in the x ray patterns the surface oxidation of ce3 to ce4 on surfaces and the probable formation of ce oxides cause this element to present a smaller quantity of exchangeable ions the presence of cerianite grains in one superficial soil sample shows that ce is mostly found in the ce4 state in the soil profile the mocambo granitic massif displays substantial enrichment in reey 555 1229 ppm for the parental granite and 569 ppm for the greisen and the exchangeable reey concentrations in the soils horizons more than 600 ppm in particular representing a potential target for an ion adsorption type rare earth elements deposit

quantifying parameter uncertainty in a large scale glacier evolution model using bayesian inference application to high mountain asia the response of glaciers to climate change has major implications for sea level change and water resources around the globe large scale glacier evolution models are used to project glacier runoff and mass loss but are constrained by limited observations which result in models being over parameterized recent systematic geodetic mass balance observations provide an opportunity to improve the calibration of glacier evolution models in this study we develop a calibration scheme for a glacier evolution model using a bayesian inverse model and geodetic mass balance observations which enable us to quantify model parameter uncertainty the bayesian model is applied to each glacier in high mountain asia using markov chain monte carlo methods after 10 000 steps the chains generate a sufficient number of independent samples to estimate the properties of the model parameters from the joint posterior distribution their spatial distribution shows a clear orographic effect indicating the resolution of climate data is too coarse to resolve temperature and precipitation at high altitudes given the glacier evolution model is over parameterized particular attention is given to identifiability and the need for future work to integrate additional observations in order to better constrain the plausible sets of model parameters

the svalbardian ellesmerian deformation of the old red sandstone and the pre devonian basement in nw spitsbergen svalbard

granites and the geodynamic history of the neoproterozoic brasilia belt central brazil a review abstract recent field and geochronological studies have demonstrated the importance of granitic magmatism in the evolution of the neoproterozoic brasilia belt in central brazil this is an orogenic belt developed in response to the convergence between the amazon sao francisco congo and parana continental blocks the presence of neoproterozoic juvenile arc rocks and syn collisional peraluminous granites challenged previous intracontinental evolution models for the belt the granitoid intrusions reviewed in this paper record the different stages of evolution of the orogen and their field and isotopic characteristics can be used to reconstruct the tectonic history of the belt the main field and isotopic characteristics of four granite suites associated with the brasilia belt are reviewed i 1 77 1 58 ga old rift related a type granite intrusions ii ca 0 8 0 7 syn collisional granitoids iii arc metatonalites and metagranodiorites ca 0 9 to 0 63 ga and iv bimodal post orogenic suite ranging in age from ca 0 59 to 0 48 ga these rocks suggest that during most of the neoproterozoic the western margin of the sao francisco continent faced a large oceanic basin where subduction and oceanic lithosphere consumption started at ca 0 9 ga roughly coeval with the initial stages of the break up of rodinia final ocean closure happened at ca 0 63 0 60 ga with crustal thickening uplift and erosion post orogenic extension related magmatism took place between ca 0 6 and 0 5 ga and was partially contemporaneous with the deposition of the paraguay and tucavaca sedimentary successions resulting from the rifting event related to the break up of laurentia from southwestern gondwana

geochemistry of mineralization with exchangeable rey in the weathering crusts of granitic rocks in south china abstract mineralization with exchangeable rare earth element ree and yttrium mex rey has been recognized in the weathering profiles in south china since the early 1970 s this type of rey mineralization occurs in weathering profiles of parent rocks ranging in composition from granite to acidic volcanic rocks and lamprophyre the majority of the known resources occurring in the weathering profiles of granitic rocks total resources of this type of rey amount to millions tons of rare earth oxides and therefore represent one of the most important types of rare earth resources in china particularly for heavy rare earth elements hree and yttrium accumulation of rey in the weathering profiles of granitic rocks is strongly controlled by the resistance to weathering of the principal rey bearing accessory minerals in the parent rocks only a limited proportion of total rey 4 and na etc in electrolyte solutions and can be removed by complexing agents such as edta are commonly the major form of ree occurrence in the b horizon cerium is enriched in the top layer a horizon and depleted in the subsurface horizons of the weathering profiles most likely due to the oxidation of ce iii to ce iv followed by cerianite formation or absorption onto clays and or fe and al oxyhydroxides