magma types and the tectonic evolution of the swedish proterozoic information on tectonic evolution can be obtained from the succession of magmatic types represented i type and s type granitoids and volcanics basic dykes and alkali complexes the earliest proterozoic magmatic activity resulted in the formation of greenstone belts within the karelian continent area probably in the age range 2500 2100 ma this was followed by an event similar to andinotype orogeny at around 1900 ma with i type granitoids and calc alkaline volcanics this progressed to an event of hercynotype which was concluded by about 1750 ma subsequent magmatic activity i type granitoids and volcanics suggests a new phase of andino type orogeny until about 1630 ma s and c sweden or 1500 ma n sweden tension related magmatism at around 1550 ma basic dykes alkaline complexes and gabbro may relate to rifting prior to the independant evolution of sw sweden which includes intrusion of i s type granitoids metamorphism followed by continental rotation and collision with n america at about 1050 ma basic dykes and s type granites are related to subsequent uplift 950 850 ma ago

u pb zircon ages of basement gneisses and discordant felsic dykes from vestranden westernmost baltic shield and central norwegian caledonides four new u pb zircon ages are reported from northern vestranden the northernmost part of the western gneiss region of norway scandinavian caledonides the age of a basement tonalite 1819 6 ma together with earlier datings on granites indicates that the dominantly granitoid basement in vestranden began to form more than 1800 ma years ago the minimum age of a subsequent precambrian migmatization event is given by a u pb age of 1630 80 ma found a granite dyke which cuts migmatitic veining in the basement gneisses while age and lithology suggest general similarity and thereby favour a correlation between the basement granites of the northern part of vestranden and svecofennian granites farther to the east no detailed chronological information is at present available that support such a correlation

the late archaean to early proterozoic lead isotopic evolution of the northern baltic shield of norway sweden and finland abstract the late archaean rocks of the northern baltic shield comprise high grade gneiss terrains and granite greenstone terrains the high grade gneiss terrains consist mainly of older upper crustal material which became metamorphosed during the lopian orogeny ca 2 9 2 6 ga in contrast the 2 7 ga old granite greenstone terrains comprise mainly mantle derived materials at the southern and western edge the archaean craton became partially remobilized during the svecofennian orogeny 2 0 1 75 ga this orogeny represents a major crust forming event in the baltic shield during which mantle material was added to the crust and older material was remobilized whole rock galena and sulfide trace lead are used to outline lead provinces on the northern baltic shield the archaean lead from the baltic shield defines three secondary lead isochrons at 2 65 ga with different initial lead compositions which reflect average pre 2 65 ga 1 ratios of 8 0 8 1 and 8 3 respectively the variation of the initial lead composition of the high grade gneisses and tonalites lofoten and koitelainen area probably indicates 1 variable crustal residence time and or 2 different degrees of crustal contamination assimilation before the 2 65 ga metamorphic event and the lead from the eastern finland greenstone belts indicates a heterogeneous mantle with respect to u pb before 2 65 ga lead in proterozoic rocks of the different lead provinces defines sets of subparallel mixing fields which can be modelled by a 2 65 ga lead component and a 1 8 ga lead component the parallel offset of these fields reflects the pre 2 65 ga 1 ratio of these terrains i e it reveals the pre 2 65 ga 1 of the involved archaean rocks proterozoic terrains with involvement of archaean lower crustal lead show a poor correlation in the 206 pb 204 pb 208 pb 204 pb diagram whereas the other proterozoic terrains show a good correlation in the 206 pb 204 pb 208 pb 204 pb diagram

new lead isotope determination from five proterozoic sulfide deposits skellefte district sweden lead isotope analyses of 25 sulfide samples galenas iron sulfides and sulfosalts from five different mines of the skellefte district northern sweden demonstrate that the pb isotopic composition of galenas and other sulfides rich in lead varies between individual deposits within the district this contrasts with many other base metal districts where ore lead is isotopically homogeneous on a regional basis although all of the skellefte leads are depleted in 207pb relative to average global lead evolution models thus suggesting a large mantle derived component in their sources the nasliden deposit lying at the contact of the host volcanic rocks and the overlying metasediments contains a significant component of crustal lead it is concluded that while the pb isotope data are consistent with a volcanic exhalative origin of the ores of the skellefte district they also demonstrate that older crustal lead was incorporated into the sulfides during their emplacement and the subsequent period of magmatic and metamorphic activity which followed their deposition

thermodynamic models of biotite pseudomorphs after staurolite muscovite bearing pelites near rangeley maine the proportion of muscovite rich to biotite rich pseudomorphs in the model is a function of the initial proportions of muscovite plagioclase and staurolite which govern the proportion of staurolite that is enclosed by sillimanite segregation mantles modified journal abstract

digital close range photogrammetry for the study of rill development at flume scale abstract soil erosion is a continuous process of detachment transportation and deposition of soil particles obtaining accurate descriptions of soil surface topography is crucial for quantifying changes to the soil surface during erosion processes the objective of this study was to develop an improved close range photogrammetric technique to assess soil erosion under rainfall conditions based on high overlapping image acquisition digital point cloud matching digital elevation model dem generation and soil erosion calculation a digital close range photogrammetric observation system was explored and established the results showed that the established digital photogrammetric observation system could accurately calculate the digital point cloud from the underlying surface with a 2 min time interval and a 1 5 mm spatial resolution in addition based on the dem generated from digital point clouds the amount of soil erosion in different topographic positions within various time periods was calculated the digital photogrammetric observation methods explored in our study provide a reliable way to monitor soil erosion processes especially under rainfall conditions this approach can accurately resolve the evolution of the underlying surface soil erosion which is of great importance in understanding soil erosion mechanisms

evidence from mineral assemblages for infiltration of pelitic schists by aqueous fluids during metamorphism prograde mineral assemblages and compositions have been predicted for pelitic schist in the 10 component system na2o k2o cao mno feo mgo al2o3 sio2 co2 h2o for three cases of prograde metamorphism and fluid rock interaction 1 increasing temperature t at constant pressure p and constant pore fluid volume 1 without infiltration no infiltration case 2 increasing t at constant p accompanied by sufficient fluid infiltration that fluid composition is at all times constant large flux case and 3 increasing t at constantp accompanied by a timeintegrated fluid flux f 104 cm3 cm 2 intermediate flux case stable mineral assemblages and compositions were calculated by solving a system of non linear equations that specify mass balance and chemical equilibrium between minerals and fluid the model pelitic system includes quartz muscovite plagioclasc chlorite ankerite siderite biotite garnet staurolite andalusite kyanite sillimanite k feldspar and a coexisting binary h2o co2 fluid specifically prograde thermal metamorphism was modelled for shaw s 1956 average low grade pelite and for a moderate range of bulk rock compositions at p 3 5 and 7 kb and initial fluids with xco 2 o 0 02 0 40 the model predicts a carbonate bearing mineral assemblage for average pelite under chlorite zone conditions composed of quartz muscovite albite chlorite ankerite and siderite the mineral assemblages predicted for the noinfiltration case are unlike those typically observed in regional metamorphic terranes simulations of metamorphism for the large flux and intermediate flux cases however reproduce the sequence of mineral assemblages observed in normal barrovian regional metamorphic terranes these results suggest that regional metamorphism of pelitic schists is typically associated with infiltration of significant quantities of aqueous fluid

geology geochemistry age and geotectonic evolution of the dala granitoids central sweden abstract the dala granitoids and their associated volcanic products are part of a major palaeoproterozoic igneous complex the 1 85 1 67 ga transscandinavian igneous belt tib in the fennoscandian shield tib constitutes the south western border of the svecofennian domain which was formed by an orogenic episode at 1 93 1 83 ga earlier plate tectonic models proposed that tib is a postorogenic batholith complex which was formed in a compressional tectonic regime representing an andino type environment whereas an extensional tectonic regime has been proposed for the anorogenic 1 65 1 51 ga rapakivi granites in the svecofennian domain in this paper a key segment of tib the dala granitoids is discussed in order to focus attention on the post to anorogenic magmatic evolution in the svecofennian domain three types of granitoids jarna siljan and garberg can be distinguished within the dala granitoid complex the jarna granitoids are the most primitive and were emplaced at a significant depth in the crust at ca 1 79 ga the 1 70 1 68 ga siljan and garberg granites are more evolved and were emplaced at a shallow level in the crust closely associated in space time and origin with the volcanic dala porphyries field relationships as well as geochemical and geochronological data indicate magma genesis within a compressional tectonic regime for the 1 79 ga jarna granitoids however most of the dala granitoids appear to have formed in an extensional tectonic regime which was initiated during the last phase of tib magmatism this extensional igneous component is represented by the 1 70 1 68 ga high level siljan and garberg granites and their closely associated volcanic products the dala porphyries an improved model for the formation of the post to anorogenic magmatism in the svecofennian domain suggests that the dala granitoids represent a post to anorogenic igneous key complex which reflects the transition from a compressional to an extensional tectonic environment along a plate boundary

geothermometry geobarometry and the al2sio5 triple point at mt moosilauke new hampshire the distribution of aluminum silicate minerals in pelitic schists constrains pressure and temperature conditions during the acadian orogeny to have been approximately those of the al 2 sio 5 invariant point thus providing an excellent opportunity to evaluate the internal consistency of a variety of published geothermometers and geobarometers with the al 2 sio 5 invariant point of holdaway 1971 four fluid independent equilibria yield p t estimates consistent with holdaway 1971 two fluid dependent equilibria yield internally consistent but unrealistically high temperatures our data are consistent with the conclusions that 1 only pyrope grossular mixing in the quaternary garnet system is significantly non ideal and 2 the activity coefficient for the anorthite component in plagioclase is approximately 2 at triple point p t conditions modified journal abstract

internally consistent geothermometry and h 2 o barometry in metamorphic rocks the example garnet chlorite quartz temperature and h2o activity can be determined with high precision using metamorphic mineral assemblages that define both a dehydration equilibrium and a temperature sensitive cation exchange equilibrium such determinations are obtained by applying the gibbs method and then integrating two resulting differential equations as illustrated here for the assemblage garnet chlorite quartz the first equation a geothermometer that monitors temperature based upon fe mg exchange between garnet and chlorite was calibrated using rocks at pecos baldy new mexico 0 0 05 p bars 19 02 t k 4607 ln kd 24 156 with errors of 8 c based upon analytical precision the second equation monitors differences in the activity of water between specimens 1 and 2 0 0 1 xmg chl 1 2 05 p2 p1 33 02 5 96 ln xfe chl 1 xalm 1 t2 t1 2 67 rt1ln a h2o 2 a h2o 1 5 96 t1ln xfe chl 2xalm 1 xfe chl 1xalm 2

close range digital photogrammetric analysis of experimental drainage basin evolution brasington james smart r m a 2003 close range digital photogrammetric analysis of experimental drainage basin evolution earth surface processes and landforms 28 3 pp 231 247 rae2008 special issue the generation of high quality topographic data for hydrology and geomorphology

erosion rates in badland areas recorded by collectors erosion pins and profilometer techniques ebro basin ne spain abstract in badland areas of the ebro basin in a semiarid climate two erosion plots 257 m2 5 slope and 128 m2 23 slope on exposed tertiary clays were monitored over two years nov 1991 nov 1993 this material is characterized by high sodium absorption ratios which lead to high soil dispersivity the dominant erosion processes in both plots are rilling and sheet erosion rainfall intensity was recorded at a weather station connected to a data logger sediment production for single events was collected in tanks and ground lowering was measured every six months by erosion pins and microtopographic profile gauge techniques significant runoff was produced only by rainfall events above 5 mm another threshold at 20 mm rain was noted for rainfalls higher than 20 mm the 23 slope plot shows a greater runoff response than the 5 one rainfall events exceeding this threshold showed a higher sediment production for the steeper slope in the relationship between precipitation and sediment concentration an envelope curve can be drawn indicating that any rainfall event of a given amount and intensity has a maximum sediment concentration which we speculate to be a function of the runoff sediment transport capacity runoff response and sediment yield in the studied plots are controlled by the rainfall and soil characteristics and their seasonal variations in both plots the erosion pins show that erosion rates in rill areas are 25 50 higher than in the interrill areas sediment yield recorded by collector devices was higher than the rates measured by erosion pins the erosion rates based on rill cross sections by profilometers were higher than the ones recorded by collectors

granites and early proterozoic crustal evolution in sweden evidence from smnd upb and o isotope systematics abstract u pb zircon and whole rock rb sr sm nd and o isotope results are reported for granitoids from three proterozoic provinces in sweden that represent different crustal environments the radiometric ages span the period 1 89 1 65 ga and record events ranging from original igneous crystallisation to late metamorphic resetting these events occurred at different times in the crustal segments the o isotope ratios identify different crustal source materials for the granitoids the sm nd results indicate that the major crustal source components common to most of the granitoids formed shortly before 1 9 ga close in time to the formation of the earliest granitoids contributions from recycled archaean basement are minimal the geographically widespread occurrence of such crustal sources indicates that the period around 2 ga was of great importance for the growth of new continental crust in sweden

influence of piedmont sedimentation on erosion dynamics of an uplifting landscape an experimental approach models of relief development generally assume that eroded products are evacuated far from the landscape whereas in nature they are often deposited at the foot of mountain belts within continental environments because piedmont aggradation can modify the base level for erosion we investigate the influence of piedmont sedimentation on the dynamics of an upstream relief we developed an experimental study of relief dynamics using laboratory scale models submitted to uplift under runoff driven erosion we compare the dynamics of topographies surrounded or not by a depositional belt made of eroded products coming from upstream piedmont aggradation acts on the dynamics of the upstream relief by modifying the relative uplift rate applied uplift rate minus aggradation rate that denudation tends to balance relief denudes at a lower rate than the applied uplift rate so the mean elevation of the uplifting topography rises when the time scale of aggradation is higher than the time scale of relief development the topography cannot reach a steady state between denudation and the applied uplift rate as long as aggradation occurs however in this case denudation balances a continuously varying relative uplift rate during a dynamic equilibrium phase of the topography

the geochemistry of early proterozoic metavolcanic rocks hosting massive sulphide deposits in the skellefte district northern sweden the skellefte district an early proterozoic massive sulphide ore province in northern sweden contains a well preserved volcano sedimentary rock association referred to as the skellefte group metamorphosed predominantly under low grade conditions the volcanic rocks in the lower part of the succession host the massive sulphide deposits and comprise a bimodal sequence composed of a calc alkaline group of felsic rocks and a tholeiitic group of mafic rocks displaying a basaltic to andesitic composition derivation of the felsic rocks by fractional crystallization from the mafic rocks is not supported by the geochemical data application of tectonic environment discriminant diagrams involving the elements ti zr y and cr suggests that these rocks were deposited in a volcanic arc setting stratigraphically above the volcanic rocks hosting the massive sulphide deposits there follows a sequence of metamorphosed greywackes and pelitic sediments with intercalation of primitive basaltic to ultrabasic volcanic and high level intrusive rocks the volcanic rocks show geochemical similarities to both archaean basaltic komatiites and phanerozoic boninites the primitive nature of these rocks present difficulties in assessing their palaeotectonic setting a volcanic arc or transition to an inter or back arc rift situation is suggested

origin of continental crust of 1 9 1 7 ga age nd isotopes in the svecofennian orogenic terrains of sweden initial nd isotopic ratios are reported for 57 samples representing all crustal components in the central and southern parts of the 1 9 1 7 ga old svecofennian orogenic terrains of sweden and the 1 8 1 7 ga old transscandinavian granite porphyry belt transscandinavian igneous belt u pb zircon ages are determined where the magmatic ages were not sufficiently constrained the nd isotopic results show that there are no archaean crustal blocks within the studied 1 9 1 7 ga old crustal segment this is consistent with results from finland the main input of recycled archaean crust to the svecofennian was in the form of sediments which are concentrated in the central svecofennian subprovince of north central sweden this is consistent with the vicinity of this subprovince to the archaean craton of the baltic shield these turbidite sediments contain up to 40 archaean material but s type granitoids associated with them have a smaller archaean component around 20 most of the quantitatively predominant i type granitoids and volcanics as well as all the basaltic rocks studied have nd from 1 to 3 and consist of 90 material newly derived from the mantle 1 9 1 7 ga ago we argue that the archaean material was introduced in the form of sediments but we cannot distinguish between pelagic sediments delivered on subducting oceanic crust and turbidite accumulations like the ones seen in north central sweden in either case an overall 15 archaean contribution for the swedish svecofennian was reasonably well homogenized with mantle derived magmatic products for this to occur an active near surface tectonic environment such as a complex of subduction zones must have been necessary

detailed recording of gully morphology in 3d through image based modelling abstract the ability to understand gully erosion development is closely related to our ability to quantify the morphology of gullies at present various technologies are at hand to collect data at increasing levels of detail however many of the developed technologies are time consuming difficult to apply or expensive as an alternative image based modelling offers a cost efficient flexible and rapid method to quantify gully morphology from photographs taken in the field in this study the use of image based modelling was tested and fine tuned to quantify the morphology of four gully heads in contrasting biophysical environments prone to gully erosion two bank gullies in central belgium and two permanent gullies in northern ethiopia ground photographs n 88 235 were taken with a reflex canon eos 450d camera having a 20 mm wide angle lens with a fixed focal length the data collection occurred during days of 30 100 cloud cover and after removing excessive vegetation in the gullies processing of the photographs occurred in photoscan 1 0 2 software using the semi automated structure from motion multi view stereo sfm mvs workflow and allowed to produce 3d digital elevation models with accuracies that range from millimetres to centimetres in addition for the same surface 2 5d models were created in arcgis gully morphological properties were derived and included cross sections total volume and volume of undercut walls and soil pipe inlets for the volume calculation optocat software was used cross sections were also quantified by tape meter measurements when compared to 3d models cross sections quantified from tape meter measurements and from 2 5d models underestimate the cross sectional area by

a field and theoretical analysis of garnet chlorite chloritoid biotite assemblages from the tri state ma ct ny area usa the prograde evolution of minerals in metapelites of a barrovian sequence from the tri state area massachusetts connecticut new york of the taconic range involves assemblages with garnet ga chlorite ch chloritoid ct biotite bi and staurolite st detailed petrologic observations mineral compositions and chemical zoning in garnet show 1 garnet high in mn and fe but low in mg is stable with chlorite at grades below those where chloritoid biotite is found 2 early formed garnet reacted partially to form ct bi at intermediate grades 3 at higher grades garnet with low mn chlorite is again produced at the expense of chloritoid biotite suggesting a reversal in the continuous reaction involving the phases ga ch ct and bi thermodynamic modeling of the assemblage ga ch ct bi st in the mnkfmash system reveals 1 in the mnkfash system the prograde reaction is ga ch ct bi whereas in the kfmash system the prograde reaction is the opposite ct bi ga ch 2 the ga ch ct bi st invariant point in the kfmash system occurs twice at approximately 6 5 kbar 545 c and 14 8 kbar 580 c although one of them may be metastable in a complex phase system the appearance of the petrogenetic grid is markedly different from that of albee but similar to that of spear and cheney 3 as a consequence in the kfmash system chloritoid biotite are stable over a wide range of p t conditions whereas garnet chlorite assemblages are restricted to a narrow band of p t conditions 4 mno increases the stability field of ga ch relative to both ct bi at low temperatures and st bi at high temperatures 5 in natural samples the occurrence of ct bi is controlled more by bulk mg fe mn composition than p t conditions specifically ct bi is restricted to bulk compositions with fe mg fe mn 0 6 rocks with fe mg fe mn 0 5 are likely to display only chlorite biotite at low grade these observations are consistent with wang and spear and spear and cheney

local and regional differences in the chemical potential of water in amphibolite facies pelitic schists mineral assemblages in different samples of amphibolite facies pelitic schists collected from two separate outcrops in the moosilauke area nh record differences in the chemical potential of water during metamorphism mineralogical petrological and field relations indicate that mineral assemblages at both outcrops equilibrated at 520 c and 3 5 4 0 kbar thermodynamic analysis of the mineral assemblages demonstrates that maximum chemical potential differences at each outcrop were of the order of 150 calories over distances of 10 20 m the differences in the chemical potential of water recorded in both bed to bed and outcrop to outcrop relations are consistent with the following conclusions 1 mineral assemblages on a specific outcrop did not equilibrate with an external reservoir of fluid of fixed composition 2 the relatively small magnitude of the chemical potential differences suggests little or no infiltration of externally derived fluid 3 these differences on the outcrop scale are probably related to initial compositional variations and the buffer capacity of the mineral assemblage and 4 the different values of the chemical potential of water exhibited by the various mineral assemblages permits an understanding of the effects of variable h2o for amphibolite facies pelitic schists

geochemical characteristics of granites associated with proterozoic molybdenite mineralization in northern sweden abstract proterozoic molybdenite occurrences in northern sweden are associated with small plutons of intrusive character located in supracrustal belts whereas large granite areas are barren in this study 152 samples of granites associated with molybdenite mineralization mineralized aplites granites not known to be associated with molybdenite occurrences but located in supracrustal belts and granites from the large granite areas have been analysed for major elements and the selected trace elements mo sn be ba rb sr cu zn zr v y nb f cl and s the study showed that major element geochemistry and modal composition are not useful for distinguishing between potentially molybdenite mineralizing and barren granites in northern sweden enriched contents of sn be y rb and f are most useful for identifying ore associated granites in the supracrustal belts the granites from the large granite areas have very low contents of sn mo be nb y f cl and s it is proposed that the granites associated with molybdenite occurrences were probably generated by partial melting of earlier igneous rocks or they may be of subcrustal origin the large granite bodies originated by partial melting of archean continental crust

computing spatially distributed sediment delivery ratios inferring functional sediment connectivity from repeat high resolution digital elevation models high resolution digital elevation models dems from repeat lidar or sfm surveys have become an important tool in process geomorphology the spatial pattern of negative and positive changes of surface elevation on raster dems of difference dod can be interpreted in terms of geomorphic processes and has been used for morphological budgeting we show how the application of flow routing algorithms and flow accumulation opens new opportunities for the analysis of dod by accumulating the values of the dod along downslope flowpaths delineated on a dem these algorithms lend themselves to computing the net balance i e sediment yield sy for the contributing area of each cell doing the same for the negative subset of the dod yields a minimum estimate of erosion e within the contributing area the division of sy by e yields a maximum estimate of the sediment delivery ratio sdr that is the proportion of material eroded within the contributing area of each cell that has been exported from that area the resulting sdr is a spatially distributed measure of functional sediment connectivity in this letter we develop the computationally simple approach by means of an example dod from a lateral moraine section in the upper kaunertal valley austrian central alps we also discuss advantages assumptions and limitations and outline potential applications to connectivity research using field laboratory and model based dod

geological geochemical and geochronological evidence for a new palaeoproterozoic terrane in southeastern sweden the geological and geochronological relationships between a rhyolite belonging to the transscandinavian igneous belt tib and an intrusive suite the backaby intrusion southeast sweden have been investigated by means of bedrock mapping geochemistry and radiometric age determinations u pb on zircons field relations suggest that the rhyolite rests unconformably on the backaby intrusion which previously has been correlated with 1 9 ga granitoids within the svecofennian domain the rhyolite yielded an age of 1800 8 ma and a tonalite belonging to the backaby intrusion basement yielded an age of 1834 3 ma the age of the rhyolite is slightly older 10 15 ma than adjacent granitoids belonging to the transscandinavian igneous belt and is considered as the earliest magmatic expression of tib in the area the age and the geochemical trends for the backaby intrusion is significantly different from that of the surrounding tib granitoids and indicate a rock forming event at about 1830 1840 ma in southeastern sweden represented by the oskarshamn jonkoping belt this event is significantly younger than the older svecofennian rocks within the svecofennian domain proper indicating a hitherto unidentified geological terrane in southeastern sweden

the mineral chemistry of hydrothermally altered and metamorphosed wall rocks at the stollberg fe pb zn mn ag deposit bergslagen sweden the c 1 9 ga old stollberg sulphide and mnrich skarn iron ores and sulphide ores in bergslagen south central sweden are hosted by hydrothermally altered and metamorphosed felsic volcanic and volcaniclastic rocks the ores are underlain by comformable alteration zones characterized by albite gedrite quartz and biotite muscovite plagioclase k feldspar quartz garnet assemblages the present mineralogies are interpreted as medium grade metamorphic equivalents to the original alteration mineral assemblages pt conditions during prograde regional metamorphism are semiquantatively determined to be 510 to 560 c at approximately 3 kbar with increasing modal content of gedrite and biotite in the alteration zones the mg fe ratios and xmg s in octahedral positions of these minerals also increase in the gedrite bearing strata whole rock mg fe ratios remain constant whereas in the biotite rich unit the wholerock mg fe trend is parallel to that of the biotites

jorn an early proterozoic intrusive complex in a volcanic arc environment north sweden abstract the jorn complex is an early svecokarelian granitoid suite intruded into a volcanic arc environment on the southern margin of a major proterozoic continental area both the complex and its country rocks have been affected by hydrothermal alteration and low grade regional metamorphism four phases can be distinguished on geological chemical and geophysical criteria in particular a heterogeneous calcic outer zone and a more evolved central diapir the rock types vary from granodiorite to granite and have major and trace element abundances similar to those phanerozoic subduction related granitoids from relatively immature volcanic arcs zircon populations from the different phases are rather heterogeneous but do not show significant differences in u distribution or u pb age between the phases while pooled u pb data 13 points give an upper intercept of 1890 7 8 ma a two stage model assuming an age difference between cores and rims gives a more probable crystallisation age of 1876 2 ma with significant lead loss at 1720 ma and 410 ma epsilon nd values range from 1 8 to 3 2 indicating that the source material for the jorn complex was derived from an lree depleted mantle with a small contribution of older crustal material and had a relatively short crustal residence period metaluminous compositions and oxygen isotope ratios suggest non pelitic sources the jorn complex probably originated as a series of subduction related melts of basic to intermediate composition which underwent varying degrees of subsequent differentiation and secondary alteration

the dynamic process of slope rill erosion analyzed with a digital close range photogrammetry observation system under laboratory conditions abstract as the main process of soil erosion in the loess plateau of china rill erosion accounts for a large proportion of the total erosion on the slope quantifying the rill shape is crucial for studying the mechanisms and evolution of rill erosion the objective of this study is to monitor the dynamic process of slope rill erosion using on a digital close range photogrammetry observation system during continuous rainfall artificial simulated rainfall experiments were conducted and images were obtained at different time intervals we used hydrological analysis and profile analysis tools in geographic information system gis technology to extract rill networks and their main parameters to quantitatively describe the erosion processes of rill morphology the results showed that 1 compared with the error from the traditional runoff sediment measurement method the average error of the system for estimating soil loss was 7 06 and 1 05 respectively and the highest precision for a single observation was 99 46 2 the rill erosion process could be divided into several stages raindrop splashing eclipse drop pit erosion cave rill cutting head rill erosion rill network and 3 after rainfall lasted for 80 min the density and the degree of splitting increased continuously and the maximum rill width and depth both showed fluctuating trends the area of 7 5 m to 9 5 m away from the top of the surface was the most active area of rill erosion the digital close range photogrammetric observation system can accurately obtain evolution information about rill erosion morphology during continuous rainfall which provides a reference for future studies of soil erosion processes

post svecokarelian andinotype evolution in central sweden granitoids and associated volcanics postorogenic in relation to the svecokarelian orogeny constitute a belt in central sweden evidence presented in this paper suggest that the belt originated in an andinotype orogenic environment the inferred development of the belt was characterized by fracture controlled high level emplacement of batholiths in an ensialic setting voluminous venting of ignimbrites and formation of grabens through cauldron subsidence accompanied the recurrent intrusive activity block movements and episodes of burial metamorphism appear to have been prominent features throughout the history of the post svecokarelian belt