spatial and temporal isotopic domains of contrasting igneous suites in western and northern sulawesi indonesia abstract palaeocene to pliocene magmatism in nw sulawesi shows a progression from an older series with calc alkaline tholeiitic signatures 51 17 ma to a younger series of mafic intermediate high k magmas 14 5 ma and felsic k rich calc alkaline cak magmas 9 2 ma the isotopic and geochemical compositions of the older series samples indicate that the more westerly samples have been generated in a continental arc setting and the more easterly samples in an oceanic arc this distinction defines the boundary between the western and northern sulawesi tectonic terranes the younger series high k magmas have unusual isotopic compositions with variable but low 143nd 144nd high 87sr 86sr values and high 208pb 204pb for their 206pb 204pb ratios compared to subduction related magmas the diversity of the isotopic compositions points towards a source with a long and heterogeneous geochemical evolution most likely located within the australian subcontinental lithospheric mantle the younger series felsic cak magmatism has a more homogeneous isotopic and geochemical signature and reflects melting of continental crust of australian origin this geochemical progression in time is very similar to that seen in central sulawesi chem geol 156 1999a 67 and is best explained by normal subduction of an oceanic plate followed by melting of an underthrust sliver of australian continent the size of this microcontinent can be estimated from the areal extent of low nd isotope magmas in western sulawesi ranging from approximately 4 s to 1 n underthrusting must have happened prior to 14 ma indicating that this event cannot be equated to the collision between sulawesi and the sula platform which occurred at 5 ma while subduction beneath western sulawesi ceased prior to the onset of potassic magmatism in this region it continued beneath northern sulawesi producing predominantly calc alkaline suites

contrasting environmental memories in relict soils on different parent rocks in the south western italian alps abstract soils on the alps are usually weakly developed both because of the extensive pleistocene glaciations and because of slope steepness and climate enhancing erosion however on some stable relict surfaces particularly in the outermost sections of the alpine range some highly developed soils are apparently in contrast with holocene soil forming conditions in this work we assess the extent of pedogenesis in some of these soils located under montane level vegetation in the ligurian alps sw piemonte italy and relate it to the effects of climate and parent material the considered well developed profiles showed signs of extremely different pedogenetic processes on the different lithotypes in particular podzols with extremely thick e horizons up to more than 2 m thick and very hard thick ortstein or placic horizons were formed on quartzite reddish terra rossa luvisols were formed on limestone red extremely acidic alisols were formed on shales the chemical properties the micromorphology and the clay mineralogy demonstrated high intensity pedogenic trends and were characteristic of processes usually occurring under different climates they may therefore represent excellent pedo signatures of different specific past climatic environmental conditions as a response of different lithologies to specific soil forming environments which range from warm and humid climates typical of red alisols and luvisols to cool and humid wet climates leading to the formation of podzols with ortstein placic horizons

weathering and evolution of soils formed on granitic glacial deposits results from chronosequences of swiss alpine environments abstract two soil chronosequences of mountainous ecosystems in switzerland served as the basis to calculate the accumulation of soil organic matter transformation of pedogenic fe and al and net losses of the main elements ca mg k na fe al mn and si by means of mass balance calculations elemental losses due to deglaciation and exposure to the weathering environment were calculated these mass balance calculations indicate that extensive mineral weathering resulted in significant leaching losses of si major base cations and al particularly from the upper horizons the losses are especially pronounced in the early stages of soil formation in most cases the exponential decay model incorporating an asymptotic or logarithmic regression model seems to provide a good description of weathering the greatest changes in the soil chemistry of these alpine soils on granitic host material occurred within the first 3000 4000 years of soil development later the weathering rates decreased rapidly and the overall depletion of elements nearly reached an asymptote we also found that the mean ratio of al t fe d al d fe t of the fine earth of the a e and b horizons is closely linked to the duration of soil development a very rapid decrease of this ratio also occurred at the beginning of soil evolution in order to reach asymptotic values after about 3000 years consequently this ratio could be a good indicator of the age of alpine soils furthermore there is a close relationship between the mass of organic c or n in the whole profile and the soil age the older the soil the higher the corresponding mass per unit area the chronofunctions presented give a first attempt of the chemical soil evolution in the alps however only little data has been available up until now regarding alpine soils and this fact inhibits a more detailed observation of the changes that have occurred over a period of 2000 8000 years of soil formation under similar climatic conditions

genesis of a holocene soil chronosequence from the southernmost andes mountains tierra del fuego abstract at the southernmost andes mountains the martial cirque glacier has retreated 2 km in distance and 500 m in elevation since the mid holocene this study examines soil properties processes and classification in relation to soil age and elevation soils were sampled at elevations from 430 to 925 m a s l on drifts periodically influenced by volcanic ash that represent five age classes 5 0 to 6 0 kyr bp under deciduous nothofagus pumilio forest 1 3 to 3 2 kyr bp under n pumilio and n antarctica forest and tundra 0 3 to 1 4 kyr bp under tundra 0 3 kyr bp ce under tundra and 0 007 kyr bp ce under scattered lichens and mosses the soils represent a developmental sequence on metapellitic rocks ranging from cryorthents dystrocryepts humicryepts and humicryods in general the soils contain abundant coarse fragments sandy loam textures and high levels of organic c clays have been altered in the soils from chlorite to a hydroxyl interlayered vermiculite and ferrihydrite the most developed soils are very strongly acid al saturated and have illuvial horizons enriched in fulvic acid c and organic bound forms of free fe and al the following properties are highly correlated with soil age pyrophosphate soluble iron fep in the b horizon r2 0 97 color development equivalence in the b horizon r2 0 87 clay content of the b horizon r2 0 68 and fulvic acid c in the b horizon r2 0 65 the results of this study imply that soil formation in magellanic subantarctic forests and tundra is rapid and involves podsolization andisolization and humification as primary soil forming processes

the latest lgm culmination of the garda glacier italian alps and the onset of glacial termination age of glacial collapse and vegetation chronosequence abstract in the deglacial sequence of the largest end moraine system of the italian alps we focused on the latest culmination of the last glacial maximum before a sudden downwasting of the piedmontane lobe occupying the modern lake basin we obtained a robust chronology for this culmination and for the subsequent deglacial history by cross radiocarbon dating of a proximal fluvioglacial plain and of a deglacial continuous lake sedimentation we used reworked dinocysts to locate sources of glacial abrasion and to mark the input of glacial meltwater until depletion the palynological record from postglacial lake sediments provided the first vegetation chronosequence directly reacting to the early lateglacial withdrawal so far documented in the alps glacier collapse occurred soon after 17 46 0 2 ka cal bp which is the manerba advance culmination basin deglaciation of several overdeepened foreland piedmont lakes on southern and northern sides of the alps appears to be synchronous at millennial scale and near synchronous with large scale glacial retreat at global scale the pioneering succession shows a first afforestation step at a median modeled age of 64 years after deglaciation while rapid tree growth lagged 7 centuries between 16 4 0 16 and 15 5 0 16 ka cal bp a regressive phase interrupted forest growth marking a lateglacial phase of continental dry climate predating gi 1 this event spanning the most advanced phases of north atlantic h1 is consistently radiocarbon framed at three deglacial lake records so far investigated on the italian side of the alps relationships with the gschnitz stadial from the alpine record of lateglacial advances are discussed

biogeochemical weathering in sedimentary chronosequences of the rhone and oberaar glaciers swiss alps rates and mechanisms of biotite weathering abstract we analysed the composition of phyllosilicate minerals in sediments deposited by the rhone and oberaar glaciers swiss alps in order to identify processes and rates of biogeochemical weathering in relation to glacial erosion the investigated sediments are part of chronosequences consisting of a suspended fresh sediment in melt water b terminal moraines from the little ice age lia approximately 1560 1850 and c tills of the younger dryas interval yd approximately 11 500y bp secondary weathering products associated with the suspended sediment have not been observed we therefore exclude intermittent subglacial storage and weathering of this material and assume that the suspended sediment is directly derived from mechanically abraded bedrock this implies that biogeochemical weathering processes started once the glacially derived sediment was deposited in the proglacial area the combination of a developing vegetation cover the generally high permeability allowing the percolation of precipitation and the chemical reactivity related to the dominance of fine grained material biotite weathering rates are calculated using the difference in the biotite content between unweathered and weathered glacial sediments within the investigated profiles the reactive mineral surface area is estimated geometrically both with regards to the total relative surface wr t as well as to the relative edge surface wr e wr t biotite weathering rates are estimated as 10 13 10 15 mol biotite m 2 biotite s 1 wr e biotite weathering rates are on the order of 10 13 10 14 mol biotite m 2 biotite s 1 biotite weathering rates obtained by this study are in the order of one magnitude higher in comparison to other published field based weathering rates using biotite as an indicator we therefore suggest that glacially derived material in the area of the oberaar and rhone glaciers is generally subjected to enhanced biogeochemical weathering starting immediately after deposition in the proglacial zone and subsequently continuing for thousands of years after glacier retreat

vegetation influence on soil formation rate in a proglacial chronosequence lys glacier nw italian alps abstract climate change has huge impacts on alpine ecosystems one of the most visible effects in the alps is glacier retreat since the end of the little ice age lia which caused the exposure of previously glaciated surfaces these surfaces are open air laboratories verifying theories regarding ecosystem and soil development in order to increase our knowledge on the effects of time and vegetation primary succession on soil development in proglacial areas we sampled soils and surveyed plant communities on stable points in the proglacial area of the lys glacier in the italian north western alps valle d aosta region the sampling points were located on dated sites based on literature and or historical photographs glacial till is attacked by weathering processes immediately after deposition and stabilization with a consequent loss of soluble compounds decrease of ph and primary mineral weathering the speed of these processes was largely increased after the establishment of a continuous vegetation cover thanks to the organic matter accumulation caused by litter input and root decomposition below the soil surface on sialic glacial tills below timberline and under a quasi climax larch rhododendron forest fast and steady decrease in ph values increase in organic matter content and horizon differentiation were observed in particular genetic eluvial horizons formed in approximately 60 years while diagnostic albic horizons were developed after ca 90 years pointing to an early start of the podzolization processes cheluviations of fe and secondarily al were analytically verified however illuviations of fe al and organic matter in incipient b horizons were not sufficient to obtain diagnostic spodic horizons on lia materials under grazed grassland below timberline and alpine prairie above timberline acidification and weathering were slightly slower and no redistribution with the depths of fe and al oxi hydroxides was observed a cambic bw horizon developed on the oldest lia moraines therefore it seemed that this fast onset of the podzolization process in comparison to other proglacial chronosequences in the alps was mainly driven by vegetation properties rather than by specific climatic conditions

new paleomagnetic constraints on the cenozoic tectonic evolution of the north arm of sulawesi indonesia abstract extensive paleomagnetic sampling 34 sites was carried out in cenozoic formations of the north arm of sulawesi between 120 and 124 e consistent results obtained between 120 and 122 e suggest the existence of a unique post miocene clockwise rotation of about 20 25 of the western part of the north arm this rotation probably occurred during the northward drift of the north arm along the palu matano sinistral transcurrent fault between 122 5 and 124 e both clockwise and counterclockwise rotations with various amplitudes from 6 to 85 are encountered and these very likely correspond to individual microblock rotations due to pervasive deformation along shear zones this result is consistent with the complex fault system of the gorontalo and kotamobagu shear zones that have been recognized on radar imagery and by spot image analyses

short term geomorphological evolution of proglacial systems proglacial systems are amongst the most rapidly changing landscapes on earth as glacier mass loss permafrost degradation and more episodes of intense rainfall progress with climate change this review addresses the urgent need to quantitatively define proglacial systems not only in terms of spatial extent but also in terms of functional processes it firstly provides a critical appraisal of prevailing conceptual models of proglacial systems and uses this to justify compiling data on rates of landform change in terms of planform horizontal motion elevation changes and sediment budgets these data permit us to produce novel summary conceptual diagrams that consider proglacial landscape evolution in terms of a balance of longitudinal and lateral water and sediment fluxes throughout we give examples of newly emerging datasets and data processing methods because these have the potential to assist with the issues of i a lack of knowledge of proglacial systems within high mountain arctic and polar regions ii considerable inter and intra catchment variability in the geomorphology and functioning of proglacial systems iii problems with the magnitude of short term geomorphological changes being at the threshold of detection iv separating short term variability from longer term trends and v of the representativeness of plot scale field measurements for regionalisation and for upscaling we consider that understanding of future climate change effects on proglacial systems requires holistic process based modelling to explicitly consider feedbacks and linkages especially between hillslope and valley floor components such modelling must be informed by a new generation of repeated distributed topographic surveys to detect and quantify short term geomorphological changes

petrologic isotopic and radiometric age constraints on the origin and tectonic history of the malino metamorphic complex nw sulawesi indonesia the malino metamorphic complex mmc is located at the western end of the north arm of sulawesi it consists of mica schists and gneisses derived from proximal turbidite and granitoid protoliths with intercalations of greenschist amphibolite marble and quartzite forming an e w elongated dome like structure bounded on all sides by faults the age of the mmc is constrained between devonian and early carboniferous this paleozoic age the presence of archean and proterozoic inherited zircons and the isotopic signature of the mica schists and gneisses indicate that the terrane was derived from the new guinea australian margin of gondwana similarities with basement rocks in the bird s head suggests a common origin greenschists forming a discontinuous selvage metamorphic carapace around the complex were derived from adjacent autochthonous paleogene formations the rocks of the mmc show a barrovian type progression from greenschist through epidote amphibolite to amphibolite facies p t estimations suggest a depth of burial of up to 27 30 km k ar and 40ar 39ar cooling ages of 23 11 ma and a 7 ma age for unconformably overlying volcanic rocks indicate that the complex was exhumed during the miocene two tectonic scenarios are considered 1 the continental fragment docked with sulawesi during the mesozoic and was exhumed as a metamorphic core complex during the miocene 2 it was subducted beneath the north arm during the late oligocene and then rapidly returned back to the surface

evolution of soil pores and their characteristics in a siliceous and calcareous proglacial area soil chronosequences in alpine areas have often been applied to trace physical mineralogical and chemical soil properties over time how the soil pore system of undisturbed soils evolves however has not yet been clarified we therefore investigated two soil chronosequences in the swiss alps spanning a time period from a few decades up to the early holocene late pleistocene one soil sequence developed on siliceous parent material in the sustenpass proglacial area of the stein glacier with soils aged from 30a to 10 ka while the second developed on calcaric parent material in the klausenpass with soils aged from 110a to 14 ka proglacial area of the griess glacier we hypothesised that the overall pore size of the topsoil and consequently the relative proportion of macropores decrease with increasing soil age the pore size characteristics were determined by using x ray computed tomography independent of the parent material calcareous vs siliceous macroporosity decreased with time the greatest changes seemed to occur between the little ice age lia and about 3 4 kyr of soil evolution vegetation composition and the functional richness of the plant community exert an influence on soils that developed on siliceous parent material by giving rise to more small pores besides pore sizes pore characteristics also changed with time in general the tortuous structure of the soils became more complex with time the evolution of the pore characteristics such as tortuosity number and length of pore networks seem also to be related to biologic factors such as root properties plant species and soil organic matter composition it remains however unanswered how these time dependent biologic factors interact with and influence in detail the pore network this aspect certainly merits investigation in greater detail in the future

mesozoic cenozoic rift drift sequence of asian fragments from gondwanaland abstract the university of cambridge atlas map plotting computer program has been used to plot a reconstruction of the dispersal of continental blocks from eastern gondwanaland from the late jurassic 160 ma until the late miocene 10 ma the geological basis for the reconstruction rests on the concept of south tibet burma western thailand malaya and sumatra having been part of the eastern gondwana continent during the late palaeozoic and early mesozoic the reconstruction is also based on the view that these asian continental blocks were rifted from eastern gondwanaland in the late jurassic this rifting episode gave rise to the continental margin of central new guinea and northern australia it was associated with the sea floor spreading anomalies preserved in the floor of the northeastern indian ocean the model considers the indication of crustal uplift in the middle jurassic followed by profound subsidence in the cretaceous and palaeogene exposed in the islands of the outer banda arc from seram to timor and the similar jurassic cretaceous facies in eastern sulawesi implies that these areas formed part of this rifted northern margin of australia in the jurassic subsequent tectonic collision and associated major strike slip movements have deformed and disrupted these rock sequences during the cainozoic the date of the rifting that removed south tibet burma western thailand and malaya from gondwanaland is controversial the indications in favour of the rifting episode having occurred in the jurassic rather than in the permo triassic are stratigraphie structural observations on the northwestern australian shelf in the banda arc and in central new guinea the identification of the continental blocks removed by this rifting is based partly on stratigraphie correlation with the banda arc and new guinea and partly on indications that the age of collision of tibet burma western thailand and malaya with asia was a late cretaceous event and not triassic jurassic as is generally held there are very few reliable land based palaeomagnetic measurements to constrain the movements of these dispersed continental fragments from gondwanaland the computer generated map reconstructions put forward here fit the available indian ocean sea floor spreading data although they are not unique solutions much of the critical ocean floor data associated with the rifting and dispersal of these continental fragments has been destroyed in the tectonic collision processes that occurred at the asian continental margin

multicentury glacier fluctuations in the swiss alps during the holocene subfossil remains of wood and peat from six swiss glaciers found in proglacial fluvial sediments indicate that glaciers were smaller than the 1985 reference level and climatic conditions allowed vegetation growth in now glaciated basins an extended data set of swiss glacier recessions consisting of 143 radiocarbon dates is presented to improve the chronology of glacier fluctuations a comparison with other archives and dated glacier advances suggests 12 major recession periods occurring at 9850 9600 93008650 85508050 77007550 74506550 61505950 57005500 52004400 43003400 28002700 21501850 14001200 cal yr bp it is proposed that major glacier fluctuations occurred on a multicentennial scale with a changing pattern during the course of the holocene after the younger dryas glaciers receded to a smaller extent and prolonged recessions occurred repeatedly culminating around 7 cal kyr bp after a transition around 6 cal kyr bp weak fluctuations around the present level dominated after 3 6 cal kyr bp less frequent recessions interrupted the trend to advanced glaciers peaking with the prominent little ice age this trend is in line with a continuous decrease of summer insolation during the holocene

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

a plate tectonic model of the eastern indonesia collision zone eastern indonesia is unique in the present global plate configuration being situated at the t junction between the world s two main active orogenic belts the alpine himalayan and circum pacific belts consequently the tectonics of this region must be understood as a zone of interaction between three major plates whereas most other orogenic areas can be modelled as deformation between just two major plates with numerous intervening microplates or terranes previous models to explain the tectonics of eastern indonesia have generally started from small scale geological observations and attempted to work upwards to an overall plate synthesis in this paper i reverse the process suggesting what might be expected from one particular collision model in a three plate system and comparing this with what is actually seen in the region s geological record

rates of weathering and chemical depletion in soils across a chronosequence of lake michigan sand dunes abstract accumulation of soil organic matter and depletion of base cations and trace metals were measured in surface soils i e o horizon and upper 15 cm of mineral soil across a 4150 year soil chronosequence of dune capped beach ridges bordering northern lake michigan within 400 years of beach ridge formation coniferous forest develops soil c and n accumulate to steady state levels of 40 and 1 3 mg ha 1 respectively and the ph of the upper mineral soil decreases from 8 5 to 4 3 as carbonate minerals dissolve after substantial proportions of ca and mg have been removed an incipient spodic horizon can be observed the upper surface of which progressively deepens with increasing soil age analysis of soil strain of the upper mineral soil showed gradual dilation reaching 121 after several centuries of soil development after accounting for soil dilation quantities of ca mg p zn mn fe and v in the upper 15 cm of mineral soil decreased exponentially to low asymptotic levels representing quantities contained in weathering resistant minerals mass balance modeling indicated weathering and elemental losses in the order of decreasing decay constant as ca mg mn zn p v fe al k na ti this sequence is consistent with weathering of carbonates then ferromagnesian minerals then feldspars p levels are tightly coupled with ca losses in soils older than 200 years suggesting that ca rather than fe or al stabilizes p high concentrations of heavy metals in the organic horizon relative to the upper mineral soil indicate atmospheric inputs of industrial pollutants

permo triassic evolution of gondwanan eastern indonesia and the final mesozoic separation of se asia from australia abstract continental fragments with australian gondwanan stratigraphic affinities are widely distributed throughout the eastern indonesia collision complex despite their structural isolation from one another as a consequence of tertiary orogenesis these fragments show a remarkably uniform pattern of permo triassic tectonostratigraphy ranging from a granitoid belt in the north through a continental platform to an intracontinental rift system in the south within the rift system complementary upper and lower plate rifted margins can be recognised in the northern and southern banda arcs respectively the northern granitoid belt was initiated in the mid carboniferous whilst the intracontinental rift system began to develop in latest carboniferous earliest permian times extension in the northern rift margin ceased in the mid carnian early late triassic contemporaneous with a marked decline in igneous activity in the granitoid belt to the north the sibumasu terrane of mainland se asia probably originated on the gondwanaland continental margin adjacent to reconstructed eastern indonesia but rifted away during the early permian previous interpretations have seen this rifting as marking the final separation between gondwanaland and continental terranes now forming se asia alternatively it is suggested here that gondwanan eastern indonesia acted as an indirect continental connection between sibumasu indochina and australia during the permian and triassic this continental isthmus permitted continuing limited floral and faunal interchange between gondwanaland and se asia until a final separation in the late triassic the mid carnian structural event in eastern indonesia is interpreted as related to this separation

a tale of two eras pliocene pleistocene unroofing of cenozoic and late archean zircons from active metamorphic core complexes solomon sea papua new guinea u pb ion microprobe analyses of zircons from gneisses and granodiorites exposed in the d9entrecasteaux islands and from conglomerate sections of the goodenough no 1 well in the adjacent trobriand basin provide constraints on the age of magmatism peak metamorphism and nature of rocks unroofed during initial stages of metamorphic core complex formation in the solomon sea the youngest populations of zircons from felsic gneisses and granodiorites indicate late pliocene 206 pb 238 u ages no inherited zircons were identified in the granodiorites and the 206 pb 238 u ages 1 65 0 18 ma 1 98 0 08 ma 2 are interpreted as crystallization ages these synkinematically emplaced granodiorites intruded into actively extending continental crust are some of the youngest known granitoids currently exposed at the earth9 surface zircon ages from felsic gneisses 2 63 0 16 ma 2 72 0 28 ma 2 are interpreted to date zircon growth subsequent to eclogite facies metamorphism felsic gneiss samples also contained zircon xenocrysts from cretaceous miocene protoliths in striking contrast zircons from igneous and metamorphic clasts from the goodenough no 1 well indicate a single population with a 207 pb 206 pb age of 2781 9 ma 2 we speculate that they are derived from basement rocks unroofed during initial stages of development of the d entrecasteaux metamorphic core complexes these results provide the first direct evidence for the existence of archean protoliths in the basement rocks of southeastern papua new guinea

soil development along primary succession sequences on moraines of hailuogou glacier gongga mountain sichuan china abstract soil properties related to soil development were measured in six profiles over approximately 180 years of soil development on recessional moraines of the hailuogou glacier sichuan of southwestern china it is hypothesized that soil development is strictly time dependent field and laboratory work indicate that as soil develops from initially coarse gravel outwash the properties undergo a progressive physical and chemical change such that there is a considerable profile differentiation between the youngest and the oldest soils the ph is also highly stratified it decreases with time from 8 5 to 4 2 in the upper mineral soil and increases with depth in all profiles accumulation of soil organic c and n increases with time but the rates of accumulation become slower with time within the investigated timespan soil c and n accumulated to a considerable level of 3 5 and 0 6 kg m2 respectively with mean annual rates of 28 g m2 for carbon and 3 5 g m2 for nitrogen the rapid accumulation of organic c and n accelerates the processes of soil formation but the content of organic c and n did not reach a steady state during the observed timespan the accumulation of soil organic matter results in increased acid production and in the chemical weathering of minerals that promote formation and translocation of the clay fraction and leaching of carbonate it is also directly responsible for development of soil properties such as cation exchange capacity cec and bulk density

soil development on moraines of mendenhall glacier southeast alaska 1 the moraines and soil morphology abstract soils on a sequence of well drained neoglacial moraines up to 240 years old plus an older soil were sampled to investigate soil development through the initial stages of podzolization pebbles and cobbles in the moraines are about 75 to 80 granitic rock computations based on minerals observed optically and on chemical analyses indicate that plagioclase and quartz are the predominant minerals in the fine earth the climate is perhumid leaching of the moraines may have begun before they were free of glacial ice but little organic matter accumulated under the initial vegetative cover of sparse dwarf fireweed 10 year site as alder thicket developed organic matter accumulated rapidly in oi oe and a horizons 38 year site as spruce trees began to replace alder organic matter was lost from the surface mineral soil to form an e horizon and an incipient bs horizon formed below it an oa horizon formed and the a horizon disappeared 70 and 90 year sites organic acid leaching continued to form a spodic bhs horizon in spruce forest 240 year site and a spodic bh horizon in spruce hemlock forest 240 year site hornblende has been etched slightly within 240 years apatite has been lost from e horizons and free fe presumeably in ferrihydrite has accumulated in b horizons the younger moraine soils both with and without incipient bs horizons are typic cryorthents and the 240 year old and older soils with spodic bhs and bh horizons are typic haplocryods they are expected to accumulate more organic matter and become andic humicryods which is the most common subgroup of soils in the area

soil development on moraines of mendenhall glacier southeast alaska 2 chemical transformations and soil micromorphology abstract soils on holocene age moraines of the mendenhall glacier in southeast alaska range from morphologically undeveloped to soils having field identified spodic horizons that are more strongly expressed with increasing soil age a soil chronosequence was sampled to study development of spodic features and to compare the expression of these features with chemical and micromorphological properties organic c accumulates rapidly in these soils with o horizons forming within 38 yr organic c is highly correlated with cation exchange capacity r2 0 92 variable charge r2 0 94 extractable acidity r2 0 83 and 1500 kpa water retention r2 0 97 the ph of the 10 yr old pedon is acidic with a soil ph h20 ranging from 5 0 to 6 4 the ph decreases with soil age with the lowest ph in horizons at the organic mineral contact increases in dithionite citrate sodium pyrophosphate and acid oxalate extractable fe feo are most evident in the 240 yr old soil depth trends for these measured properties within pedons are most distinctive for fe which increases from surface mineral horizons a or e to underlying horizons in all pedons the feo fed ratio increases with soil age in b horizons and in pedons 70 yr this ratio ranges from 0 3 to 0 5 in the e horizons and from 0 4 to 0 83 in b horizons immediately below these data indicate a greater proportion of poorly crystalline fe in illuvial horizons with increasing soil age allophane content is low 240 yr old pedon this chronosequence study indicates that spodic development is achieved within a relatively short period of time in soils of this region

latest pleistocene and holocene glacier variations in the european alps in the alps climatic conditions reflected in glacier and rock glacier activity in the earliest holocene show a strong affinity to conditions in the latest pleistocene younger dryas glacier advances in the alps related to younger dryas cooling led to the deposition of egesen stadial moraines egesen stadial moraines can be divided into three or in some cases even more phases sub stadials moraines of the earliest and most extended advance the egesen maximum stabilized at 12 2 1 0 ka based on 10be exposure dating at the schonferwall tyrol austria and the julier pass outer moraine switzerland final stabilization of moraines at the end of the egesen stadial was at 11 3 0 9 ka as shown by 10be data from four sites across the alps from west to east the sites are piano del praiet northwestern italy grosser aletschgletscher central switzerland julier pass inner moraine eastern switzerland and val viola northeastern italy there is excellent agreement of the 10be ages from the four sites in the earliest holocene glaciers in the northernmost mountain ranges advanced at around 10 8 1 1 ka as shown by 10be data from the kartell site northern tyrol austria in more sheltered drier regions rock glacier activity dominated as shown for example at julier pass and larstig valley tyrol austria new 10be dates presented here for two rock glaciers in larstig valley indicate final stabilization no later than 10 5 0 8 ka based on this data we conclude the earliest holocene between 11 6 and about 10 5 ka was still strongly affected by the cold climatic conditions of the younger dryas and the preboreal oscillation with the intervening warming phase having had the effect of rapid downwasting of egesen glaciers at or slightly before 10 5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate between about 10 5 ka and 3 3 ka conditions in the alps were not conducive to significant glacier expansion except possibly during rare brief intervals past tree line data from kaunertal tyrol austria in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the swiss and austrian alps points to long periods during the holocene when glaciers were smaller than they were during the late 20th century equilibrium line altitudes ela were about 200 m higher than they are today and about 300 m higher in comparison to little ice age lia elas the larstig rock glacier site we dated with 10be is the type area for a postulated mid holocene cold period called the larstig oscillation presumed age about 7 0 ka our data point to final stabilization of those rock glaciers in the earliest holocene and not in the middle holocene the combined data indicate there was no time window in the middle holocene long enough for rock glaciers of the size and at the elevation of the larstig site to have formed during the short infrequent cold oscillations between 10 5 and 3 3 ka small glaciers less than several km2 may have advanced to close to their lia dimensions overall the cold periods were just too short for large glaciers to advance after 3 3 ka climate conditions became generally colder and warm periods were brief and less frequent large glaciers for example grosser aletschgletscher advanced markedly at 3 0 2 6 ka around 600 ad and during the lia glaciers in the alps attained their lia maximum extents in the 14th 17th and 19th centuries with most reaching their greatest lia extent in the final 1850 1860 ad advance

podzolization over ophiolitic materials in the western alps natural park of mont avic aosta valley italy abstract soil surveys carried out on ophiolitic rocks and till under subalpine forest in the natural park of mont avic aosta valley west italian alps revealed the unexpected occurrence of soils showing a horizon set typical of the podzols podzolization is uncommon on mafic and ultramafic substrata the translocation of organo metallic compounds in soils developed from such parent materials slows down considerably due to the high fe and mg contents the high base saturation and the close to neutral ph in order to determine the real origin and evolution of such soils 6 pedons selected among 83 profiles with a similar podzol morphology were sampled and analyzed chemical mineralogical and petrographic analyses of the sampled soils and parent materials were performed and correlation analysis of the obtained data was carried out results show that in favourable environmental conditions mainly climate and vegetation even mafic and ultramafic parent materials can undergo different degrees of podzolization due to the adopted diagnostic criteria the most common classification systems particularly the wrb do not allow satisfactory taxonomic arrangement of such soils

silent play in a loud theatre dominantly time dependent soil development in the geomorphically active proglacial area of the gepatsch glacier austria climate change over the last century expressed as temperature increase is substantially stronger in the european alps than the average for the northern hemisphere this leads to fast glacial retreat and permafrost degradation and hence to increased rates and risks of mass wasting more extreme floods in spring and lower base flow in summer we do not know enough about the interplay between increased proglacial mass wasting and geomorphic activity on the one hand and soil development on proglacial areas on the other hand both processes affect the attenuation of storm flow provision of base flow and the future geo pedo and biodiversity of alpine valleys however despite the known importance of soil landscape interactions soils and landscapes have so far only been studied in isolation our objective was to assess whether soil development the silent play in a geomorphically active proglacial area the loud theatre was nonetheless dominantly a function of time since glacial retreat as often observed in geomorphically inactive proglacial areas we used conditional latin hypercube sampling to select 97 locations in the gepatsch glacier proglacial area in the west of austria that best cover variation in soil age and topographic position standard soil observations were done in all locations soil development indicators were then related to time since glacial retreat and a range of geomorphic variables results indicate that time since glacial retreat indeed remains an important explanatory variable and that soil development in the gepatsch glacier proglacial area roughly equals that in some other well studied valleys geomorphic variables were found to be significant co determinants of soil development with a strong scale dependency variation in soil properties increased over time and the storage of organic matter in the proglacial area is currently in the order of 330 kg per year

an initial model of seismic microzonation of sikkim himalaya through thematic mapping and gis integration of geological and strong motion features abstract seismic microzonation and hazard mapping was undertaken in the sikkim himalaya with local site conditions and strong ground motion attributes incorporated into a geographic information system a strong motion network in sikkim consisting of 9 digital accelerographs recorded more than 100 events during 1998 2002 of which 72 events are selected with signal to noise ratios 3 for the estimation of site response sr peak ground acceleration pga and resonance frequency rf at all stations with these data and inputs from irs 1c liss iii digital data topo sheets geographical boundary of the state of sikkim surface geological maps soil taxonomy map at 1 50 000 scale and seismic refraction profiles the seismological and geological thematic maps namely sr pga rf lithology soil class slope drainage and landslide layers were generated the geological and seismological layers are assigned normalized weights and feature ranks following a pair wise comparison hierarchical approach and later integrated through gis to create the microzonation map of the region the overall sr pga and resonance frequency show an increasing trend in a nw se direction peaking at singtam in the lesser himalaya six major hazard zones are demarcated with different percentages of probability index values in the geological seismological hazard and microzonation maps the maximum risk is attached to a probability greater than 78 in the singtam and adjoining area these maps offer generally better spatial representation of seismic hazards including site specific analysis as a first level microzonation attempt

a soil chronosequence in late glacial and neoglacial moraines humboldt glacier northwestern venezuelan andes abstract late glacial and neoglacial little ice age deposits on the humboldt massif were analyzed for relative age dating parameters including geomorphic and weathering characteristics geochemical and soil properties the soil chronosequence formed in chemically uniform parent materials provides an important database to study soil evolution in a tropical alpine environment extractable and total fe and al concentrations examined to assess their use in relative age determination and as paleoenvironmental indicators provide an important measure of the accumulation and downward profile movement over time of organically bound al ferrihydrite and other crystalline forms hematite and goethite of extractable fe ferrihydrite is particularly useful in determining former perched water levels in soils with relation to paleoclimate the ratios of most fe extracts are time dependent the fe d fe t ratio within statistical limits shows a slow increase from lia little ice age to late glacial soils which closely correlates with other alpine soil studies in the middle latitudes and other tropical alpine locales values of al d dithionite and al o oxalate extractable generally do not correlate with time however al p pyrophosphate extractable measured against al t total provides insight on the downward translocation over time of organically bound al low leaching rates in this chronosequence are further supported by clay mineralogy trends and the geochemical data

chemical weathering in the foreland of a retreating glacier chemical denudation rates and strontium isotope ratios in streams vary substantially and systematically in the foreland of the retreating bench glacier in south central alaska to study weathering of young glacier sediments we sampled 12 streams draining a chronosequence of till and moraine soils derived from cretaceous metagraywacke metapelite bedrock both sediment age and vegetation cover increase with distance from the glacier cation denudation rates decline with increasing distance from the glacier whereas silica denudation rates increase carbonate dissolution and sulfide oxidation account for roughly 90 of the solute flux from the youngest sediments biotite alteration accounts for 5 11 of the solute flux its peak contribution is found in the glacier outlet stream silicate weathering is the dominant reaction only in the oldest sediments in a laboratory dissolution experiment using fresh glacial sediment carbonate dissolution dominated the solute flux during the first 700 hours paralleling the behavior of young sediments in the field in contrast to trends in the field the silica flux did not increase after the carbonate was exhausted from the reactor a possible reason for this difference is that establishment of vegetation causes an increase in silicate weathering the 87sr 86sr ratio in the glacier outlet stream is greater than that in proglacial streams and in bulk rock due to a greater contribution of biotite weathering in the outlet than in proglacial streams strontium isotope ratios decline with sediment exposure age in the proglacial streams and are consistent with a carbonate source because the dominant weathering reactions in the young sediments are of carbonate and sulfide rather than silicate minerals weathering at the glacier margin is not an important long term sink for atmospheric co2

podzol formation in sandy soils of finland abstract podzolization occurs quickly in acidic parent materials with addition of acidic litter from coniferous trees this study was conducted to evaluate podzol formation and estimate lengths of time required to meet morphological and chemical criteria of podzolic b horizon and spodic horizon in finland soil color organic c odoe and extractable al and fe were measured in a seven pedon chronosequence 230 1800 years and four older pedons 8300 11 300 years the bulk mineralogical composition of the bc and c horizons was uniform with quartz plagioclase and k feldspar as main components and amphibole illite and chlorite as minor components the fine

formation rates of smectites derived from two holocene chronosequences in the swiss alps the formation rate of smectitic components in alpine soils is derived from two chronosequences in the swiss alps covering a time span of 11 500 years the soils developed on granitic parent material the lithologies between the two chronosequences investigation areas however showed some distinct differences with respect to the main mineralogy and to a lower extent to the chemistry the chronofunctions of smectitic phase formation g kgclay year were fitted to data using an exponential formation model extensive mineral weathering resulted in significant losses of chlorite and mica and the corresponding formation of smectite and regularly and irregularly interstratified mica smectite this formation is especially pronounced in the early stages of soil formation our investigations reveal that the greatest changes in soil clay mineralogy of alpine soils on granitic or gneiss host material occur within the first 1000 3000 years of soil development at both investigation sites the annual formation rates are in a similar order of magnitude with 0 1 g kg year or even higher at the start of soil formation and with values 0 01 g kg year after about 7000 years the pedogenetic smectites from the e or bs horizons included several populations with various interlayer charges this heterogeneity seems to be related to the nature of their precursors

magmatic evolution of sulawesi indonesia constraints on the cenozoic geodynamic history of the sundaland active margin abstract tertiary and quaternary magmatic rocks from west sulawesi record the complex history of part of the sundaland margin where subduction and collision have been and are still active the present study based on petrographic data major and trace element chemistry and 40 k 40 ar dating aims to document the age and chemical characteristics of the magmatic formations from west sulawesi and to determine the corresponding constraints on the geodynamic evolution of the sundaland border the west sulawesi magmatic province includes the south arm of sulawesi ujung pandang area the western part of central sulawesi with the toraja and palu areas and finally the north arm extending from palu to manado which includes the tolitoli and manado areas paleocene magmatic activity seems to be restricted to an episode of calc alkaline magmatism in the ujung pandang area 61 59 ma the major eocene 50 40 ma magmatic event is tholeiitic and is documented in all areas except in ujung pandang it led to the emplacement of tholeiitic pillow lavas and basaltic dykes of back arc basin bab affinity these rocks are potential equivalents to the celebes sea basaltic basement from oligocene to miocene magmatic eruptions produced successively island arc tholeiitic iat and calc alkaline ca rock series the youngest iat activity occurred around 18 ma in the central part palu area and around 14 ma in the north arm tolitoli area while ca magmas were emplaced in the north arm at ca 18 ma tolitoli and manado areas typical calc alkaline activity resumed only in the north arm tolitoli and manado areas during the late miocene 9 ma and is still active in the manado region in other areas palu toraja and ujung pandang areas an important and widespread magmatic event occurred between 13 and 10 ma and emplaced k rich magmas either silica undersaturated alkali potassic basalts ak ultrapotassic basanites uk or shoshonites sh k rich activity continued in the south until the pleistocene 0 77 ma with alkali potassic ultrapotassic and shoshonitic magmas in central sulawesi toraja and palu areas the most recent magmatic event occurred between 6 5 and 0 6 ma the corresponding products are granitic rocks and widely distributed rhyolitic pyroclastic flow deposits all these rocks are acidic in character sio 2 60 with trace element and isotopic signatures sr nd pb typical of a strong continental imprint the most striking tectonic implication of this magmatic evolution is that west sulawesi can no longer be considered as a typical magmatic arc as previously assumed with the exception of the manado area beneath which subduction is still active calc alkaline and island arc tholeiitic lavas and plutonics are volumetrically minor with respect to k rich magmas their occurrence through time is also fairly restricted mostly to the period between 30 and 15 ma another important feature is the occurrence of island arc tholeiitic and calc alkaline magmas crosscutting an older terrane of bab affinity the tinombo formation manado tolitoli and palu areas as this formation is being regarded as an equivalent to the celebes sea floor the most likely explanation for this feature is the hypothesis of tectonic erosion linked to the nw dipping subduction beneath the north arm the late miocene high k magmatic activity in central and south sulawesi reflects the prevalence of a post collisional tectonic regime following the docking of microcontinents of australian origin to central sulawesi during neogene times the incompatible element enriched character of these high k rocks might reflect their derivation from a mantle source enriched through metasomatism related to a previous subduction event such a model cannot account for the plio pleistocene cak magmatism of central sulawesi the acidic composition of which does not support a derivation from an ultrabasic source the trace element patterns of the cak rocks are very similar to those of the high grade metamorphics of central sulawesi suggesting that the latter might represent their possible source such an anatectic model implies a collisional to post collisional tectonic regime limited to central sulawesi while a post subduction regime prevailed in the south

metamorphic core complexes of cordilleran type in the cyclades aegean sea greece the islands of ios and naxos in the cycladic archipelago greece contain elongate domes over which a pervasive north to north northeast stretching lineation is warped these islands may be metamorphic core complexes of cordilleran type involving middle crustal rocks drawn upward and outward from underneath the sedimentary basins now 100 km to the south from ca 25 ma onward during uplift the crystalline rocks now exposed on the islands were deformed noncoaxially in the deeper levels of a major shallow dipping ductile shear zone this shear zone may have connected with low angle normal faults in its upper levels because it is probable that its later history involved the metamorphic complexes being dragged out from under a stretching and fracturing upper plate composed mainly of unmetamorphosed sedimentary and ophiolite suite rocks this model can be extended to explain the exhumation of the high pressure low temperature metamorphic rocks on crete which with the cyclades forms a distended paired metamorphic belt separated by an active sedimentary basin