catalogue of palaeomagnetic directions and poles from fennoscandia archaean to tertiary abstract palaeomagnetic data from fennoscandia ranging from the archaean to the tertiary have been compiled into a catalogue the data are presented in table format listing precambrian data according to tectonomagmatic blocks and late precambrian phanerozoic data according to geological periods each pole is graded with the modified briden duff classification scheme the catalogue complete to the end of 1988 contains 350 entries from 31 tectonomagmatic blocks and or geological periods normal and reversed polarity data are listed separately to allow polarity asymmetries to be studied each entry also has an indexed abstract summarizing relevant information such as the age of the rock the age of the natural remanent magnetization and the basis for the assigned reliability grade all the data are stored in the palaeomagnetic data bank which will be updated annually with new data the catalogue is the basic source of data for the microcomputer based palaeomagnetic database for fennoscandia now being compiled

palaeomagnetism mafic dykes and the protogine zone southern sweden the protogine zone pz forms the border between the svecofennian and sveconorwegian domains of southern sweden intruded in the zone are three generations of mafic dykes dated 1510 ma 1180 ma and 930 ma a palaeomagnetic study of these dykes in the central and southern parts of the pz yields two main directions of magnetization a d 291 i 78 n 31 and b d 129 i 40 n 13 these directions give palaeopoles on the sveconorwegian loop of the fennoscandian apparent polar wander path apwp a third poorly defined group c yields a mean declinationof 185 and inclination of 9 with the corresponding palaeopole situated on the c 1500 1600 ma part of the apwp two other sites yield palaeopoles located in the 1200 ma part of the path the data imply that the sveconorwegian orogeny caused a remagnetization of the two older dyke generations and that this remagnetization was complete in the southern part of the pz while a few dykes retained their original magnetization in the central part of the zone either the difference between the a and b directions record appreciable apw movement during differential cooling of the pz or the a and b directions may represent an asymmetric reversal of the earth s magnetic field in the latter case they may be contemporary and have implications for the size and form of the sveconorwegian loop of the fennoscandian apwp

relative precipitation rates of aragonite and mg calcite from seawater temperature or carbonate ion control the temperature and degree of carbonate mineral supersaturation co3 2 ion concentration of seawater are the two most likely controlling variables on the compositions of recent marine carbonate cements the relative importance of these variables is difficult to assess in nature because they have similar trends with depth 0 1500 m and latitude in modern oceans we carried out laboratory experiments to investigate the relative growth rates of calcite mg calcite and aragonite in seawater as functions of both temperature 5 25 and 37 c and of carbonate ion concentration 2 5 to 15 times supersaturated with respect to calcite the precipitation rates of aragonite relative to those of calcite increase strongly with increasing temperature and are not affected greatly by changes in saturation state at 5 c calcite precipitation rates are nearly equivalent to those of aragonite regardless of the degree of saturation at both 25 and 37 c aragonite precipitation rates are much more rapid than those of calcite up to a factor of 4 except at very low saturation states calcite compositions vary from less than 5 mol mgco3 at 5 c to 14 mol mgco3 at 37 c our results suggest that the well documented shift toward precipitation of lower mol mg calcite and the decrease in abundance of aragonite cements with increasing oceanic depth and latitude can be attributed largely to lower temperatures

how well do precambrian paleomagnetic data agree with the phanerozoic apparent polar wander path a baltica case study abstract precambrian paleomagnetic data are crucial for various tectonic and geophysical applications the reconstructions of fusion and fission of supercontinents in particular due to many objective reasons the variety of stability tests for these data are abridged in comparison to phanerozoic results and is further hindered by the rather common refusal to consider the resemblance between precambrian and younger poles in this paper we selected precambrian paleomagnetic data with ages of

the importance of large benthic foraminifera to reef island sediment budget and dynamics at raine island northern great barrier reef low lying reef islands are among the most vulnerable environments on earth to anthropogenic induced climate change and sea level rise over the next century because they are low composed of unconsolidated sediment that is able to be mobilised by waves and currents and depend on sediments supplied by reef organisms that are particularly sensitive to environmental changes e g ocean temperatures and chemistry therefore the spatial and temporal links between active carbonate production and island formation and dynamics are fundamental to predicting future island resilience yet remain poorly quantified in this paper we present results of a detailed geomorphological and sedimentological study of a reef and sand cay on the northern great barrier reef we provide an empirical investigation of the temporal linkages between sediment production and reef island development using a large collection of single grain ams 14c dates large benthic foraminifera lbf are the single most important contributor to contemporary island sand mass 47 ranging from 36 to 63 at raine island reflecting rapid rates of sediment production and delivery standing stock data reveal extremely high production rates on the reef 1 8 kg m 2 yr 1 while ams 14c dates of single lbf tests indicate rapid rates of sediment transferral across the reef we also demonstrate that age is statistically related to preservation and taphonomic grade severely abraded tests moderately abraded tests pristine tests we construct a contemporary reef and island sediment budget model for raine island that shows that lbf baculogypsina marginopora and amphistegina contribute 55 of the sediment produced on the reef annually of which a large proportion 54 contribute to the net annual accretion of the island the tight temporal coupling between lbf growth and island sediment supply combined with the sensitivity of lbf to bleaching and ocean acidification suggests that islands dominated by lbf are likely to be very sensitive to short and long term climate change projections potential outcomes of this work relate to improving the understanding of the future change dynamics of reef islands in response to climate change

skeletal oxygen and carbon isotope compositions of acropora coral primary polyps experimentally cultured at different temperatures we investigated temperature and growth rate dependency of skeletal oxygen and carbon isotopes in primary polyps of acropora digitifera scleractinia acroporidae by culturing them at 20 23 27 or 31 c calcification was most rapid at 27 and 31 c we obtained a 18o temperature relationship 0 18 c 1 consistent with reported ranges for porites indicating that juvenile acropora polyps can be used for temperature reconstruction a growth rate dependency of skeletal isotopes was detected in the experimental polyps cultured at lower water temperatures when the skeletal growth rate of these polyps was also low the estimated upper calcification flux limit for a kinetic isotope effect to be observed in the 18o growth rate relationship 0 4 0 7 g caco3 cm 2 yr 1 was similar to the calcification flux in porites corresponding to a linear extension rate of 5 mm yr 1 the maximum rate at which the kinetic isotope effect is evident this result suggests that the calcification flux can be used as a measure of growth rate related isotope fractionation that is the kinetic isotope effect in corals of different genera and at different growth stages

calcium isotopes in scleractinian fossil corals since the mesozoic implications for vital effects and biomineralization through time we present a cenozoic record of 44 40 ca from well preserved scleractinian fossil corals as well as fossil coral 44 40 ca data from two time periods during the mesozoic 84 and 160 ma to complement the coral data we also extend existing bulk pelagic carbonate records back to 80 ma the same fossil corals used for this study were previously shown to be excellently preserved and to be faithful archives of past seawater mg ca and sr ca since 200 ma gothmann et al 2015 we find that the 44 40 ca compositions of bulk pelagic carbonates from odp site 807 ontong java plateau and dsdp site 516 rio grande rise have not varied by more than 0 20 over the last 80 myr in contrast the 44 40 ca compositions of mesozoic and early cenozoic fossil corals are 1 lighter than those of modern corals the observed change in coral 44 40 ca does not likely reflect secular variations in seawater 44 40 ca instead we propose that it reflects a vital effect of calcification specifically a sensitivity of coral ca isotope discrimination to changing seawater ca and or ph support for this hypothesis comes from the presence of an empirical correlation between our coral 44 40 ca record and records of seawater ca and ph since the mesozoic lowenstein et al 2003 and honisch et al 2012 we explore various mechanisms that could give rise to such a vital effect including 1 changes in calcification rate 2 changes in proton pumping in exchange for ca 2 3 variable rayleigh distillation from an isolated calcifying fluid and 4 changes in the calcium mass balance of the extracellular calcifying fluid termed here the leaky ca model we test for the dependence of seawater 44 40 ca on external seawater ca by measuring the 44 40 ca of cultured corals grown in seawater solutions with ca ranging from 10 to 15 mmol kg corals grown under elevated ca conditions show a slight 0 15 depletion of 44 40 ca at higher seawater ca a supportive but not definitive result

new rock magnetic and paleomagnetic results for the 1 64 ga suomenniemi dyke swarm se finland abstract this study represents new petrophysical and paleomagnetic data obtained for the 1 64 ga suomenniemi diabase and quartz porphyry dyke swarm associated with suomenniemi rapakivi granite we also present petrophysical data for the coeval dykes of the sipoo 1 63 ga and hame 1 642 0 002 ga 1 647 0 014 ga swarms in order to address 1 the discrepancy between the coeval sipoo and hame poles and 2 the proposed severe overprint in paleomagnetic data for rapakivi related dyke swarms in fennoscandia demagnetization of suomenniemi dyke samples revealed dominantly normal polarity magnetization carried by magnetite for the first time a few samples from the few sites have shown a trace of a reversed magnetization the combined normal n polarity direction from nine dykes sites is at d 031 2 i 07 2 with 95 10 6 k 21 8 yielding a paleomagnetic pole at plat 27 8 n plong 171 7 e with a95 7 9 k 38 4 the suomenniemi pole fulfils four of the seven quality criteria for paleomagnetic poles van der voo 1990 the new pole for the suomenniemi swarm is similar to the coeval sipoo swarm pole but distinctly different from the nearly coeval hame swarm pole the relative position of the poles compared to other well defined paleomagnetic poles for baltica indicates that the suomenniemi and the sipoo poles are slightly younger than the hame pole we show here that the original magnetization in some of the 1 64 ga dykes in suomenniemi have been overprinted with a secondary magnetization component but several dykes of the swarm lack this overprint moreover the presumably primary subjotnian remanence component for the suomenniemi dykes can be clearly isolated due to its different coercivity and or unblocking temperature from the overprinted component the same applies to the sipoo and hame dyke swarms

palaeomagnetic studies of proterozoic rocks from the lake onega region southeast fennoscandian shield summary in a recent compilation elming et al 1993 presented a new apparent polar wander path for the proterozoic of the fennoscandian shield however only a minor portion of the data used for this and for the earlier compilations has been obtained from the eastern part of the fennoscandian shield thus prompting the present study in this paper we present new palaeomagnetic data for the lake onega region the sections studied comprise quartzites as well as extrusive and intrusive rocks of vepsian 1900 1650 ma and jatulian 2300 2100 ma ages which represent svecofennian and jatulian tectonomagmatic events respectively thermal and alternating field demagnetization experiments reveal the presence of several components of the natural remanent magnetization of normal and reversed polarity component an has been identified in a sill of vepsian gabbro dolerites 1770 ma exposed at rybreka locality and yields a palaeopole at 37 8dn 210 6de dp 4 0d dm 7 7d this magnetization is interpreted to be of thermoremanent origin in the vepsian shoksha quartzite ca 1800 ma cut by the sill and in the underlying basalts the palaeopoles indicated by the presumably primary components an and ar are at 45 1 dn 206 4de dp 3 6d dm 6 5d and 44 2dn 241 5de dp 6 1d dm 9 6d respectively component an was isolated in the jatulian basaltic lavas ca 2200 2300 ma at girvas locality also however in this case it appears as secondary and yields nearly the same palaeopole 43 1dn 211 5de dp 4 9d dm 8 8d component br was isolated in vepsian gabbro dolerites and quartzites sampled from zones altered by monzonite veins representing the final phase of sill emplacement this component yields a palaeopole at 13 9dn 171 3de dp 2 4d dm 4 8d for gabbro dolerites and at 10 5dn 201 8de dp 8 4d dm 14 9d for quartzites the vepsian and jatulian rocks also show the presence of presumably younger 1500 ma magnetization components c d and e the presumably primary stable dual polarity components determined in the jatulian lavas and interlayers of the red siliceous rocks yield a palaeopole at 0 8ds 245 4de dp 7 2d dm 11 6d for the upper part of the section component f and a palaeopole at 36 0ds 307 4de dp 9 9d dm 14 9d for the lower part of the section component g these palaeomagnetic poles are compared with the apparent polar wander path of fennoscandia for the interval 2400 1200 ma after elming et al 1993 and with some recent results from vepsian and jatulian rocks

the impact of quaternary sea level and climatic change on coastal alluvial fans in the cabo de gata ranges southeast spain conventionally a fall in base level is seen as stimulating incision into the distal zones of alluvial fans in the cabo de gata ranges of southeast spain evidence exists to the contrary two sets of quaternary coastal alluvial fans demonstrate the interaction between climatically driven variations in the supply of sediment and eustatically driven changes in base level the fans are supplied from miocene volcanic terrain within which no evidence can be found for major tectonic deformation during the period of fan development the evolution of the east coast fans has been affected by variations in sediment supply and changes in sea level the west coast fans were buffered from the effects of changes in sea level by coastal barriers three phases of past sedimentation can be identified on the fans these can be differentiated on the basis of field observations of soil profiles particularly colour of the b horizons and accumulation of caco3 and laboratory analyses of sequential iron oxide extractions and magnetic mineral properties the two earlier major sedimentation phases were coincident with global glacials ca 135 ka and ca 85 10 ka based on the stratigraphy and uranium thorium dating of the coastal sediments high sea levels during the intervening interglacial and during the holocene caused erosion of the distal zones of the east coast fans which led to channel incision into the fan surfaces on the west coast fans no such incision occurred simply proximal incision by small fanhead trenches the youngest relatively minor phase of fan sedimentation has occurred during the holocene these contrasting contexts have produced differing styles of fans with telescopic fan morphology on the east coast and stacked morphology on the west coast fans the differences are reflected in the fan profiles with steeper gradients dominating the east coast fans and extensive lower gradient distal surfaces on the west coast fans fan morphometry based on analysis of the residuals from drainage area to fan area and gradient regressions also differentiates between the fan contexts the fan building phases appear to be controlled proximally by climatically driven pulses of sediment supplied to the fans these occurred during global glacials coincident with low sea levels and caused fan progradation onto the exposed foreshore the intervening global interglacials were times of little fan sedimentation and on the east coast where high sea levels were able to erode the fan toes deep through fan dissection ensued

evaluation of boron isotope ratio as a ph proxy in the deep sea coral desmophyllum dianthus evidence of physiological ph adjustment the boron isotope ratio 11b of foraminifers and tropical corals has been proposed to record seawater ph to test the veracity and practicality of this potential paleo ph proxy in deep sea corals samples of skeletal material from twelve archived modern desmophyllum dianthus d dianthus corals from a depth range of 274 1470 m in the atlantic pacific and southern oceans ambient ph range 7 57 8 05 were analyzed for 11b the 11b values for these corals spanning a range from 23 56 to 27 88 are found to be related to seawater borate 11b by the linear regression 11bcoral 0 76 0 28 11bborate 14 67 4 19 1 standard error se the d dianthus 11b values are greater than those measured in tropical corals and suggest substantial physiological modification of ph in the calcifying space by a value that is an inverse function of seawater ph this mechanism partially compensates for the range of ocean ph and aragonite saturation at which this species grows enhancing aragonite precipitation and suggesting an adaptation mechanism to low ph environments in intermediate and deep waters consistent with the findings of trotter et al 2011 for tropical surface corals the data suggest an inverse correlation between the magnitude of a biologically driven ph offset recorded in the coral skeleton and the seawater ph described by the equation ph ph recorded by coral seawater ph 0 75 0 12 phw 6 88 0 93 1 se error analysis based on 95 confidence interval ci and the standard deviation of the regression residuals suggests that the uncertainty of seawater ph reconstructed from 11bcoral is 0 07 to 0 12 ph units this study demonstrates the applicability of 11b in d dianthus to record ambient seawater ph and holds promise for reconstructing oceanic ph distribution and history using fossil corals

primary biogenic skeletal structures in multithecopora tabulata pennsylvanian abstract corals are significant components of fossil marine communities and important for paleoenvironmental reconstructions throughout the phanerozoic despite their abundance and diversity in paleozoic rocks the presence and criteria for the recognition of primary biogenic skeletal structures is highly controversial the aim of this study is a multilevel analysis of the diverse morphological elements that form well preserved specimens of the carboniferous multithecopora tabulate coral skeleton results indicate that samples are minimally altered by diagenesis but most importantly that skeletal structures are biogenic in nature and similar to those of modern and fossil carbonate producing organisms nano and microcrystals form a complex framework of different domains of crystal morphologies that comprise the bulk of the skeleton in multithecopora these domains are thought to be the possible phenotypic response of the genotype of these corals and had a structural importance during the life of the organism overall this study sheds light for a better understanding on the controversy that exists about the biogenic or abiogenic origin of the paleozoic coral microstructures

coral sr u thermometry coral skeletons archive past climate variability with unrivaled temporal resolution however extraction of accurate temperature information from coral skeletons has been limited by vital effects which confound and sometimes override the temperature dependence of geochemical proxies we present a new approach to coral paleothermometry based on results of abiogenic precipitation experiments interpreted within a framework provided by a quantitative model of the coral biomineralization process decarlo et al 2015a investigated temperature and carbonate chemistry controls on abiogenic partitioning of sr ca and u ca between aragonite and seawater and modeled the sensitivity of skeletal composition to processes occurring at the site of calcification the model predicts that temperature can be accurately reconstructed from coral skeleton by combining sr ca and u ca ratios into a new proxy which we refer to hereafter as the sr u thermometer here we test the model predictions with measured sr ca and u ca ratios of 14 porites sp corals collected from the tropical pacific ocean and the red sea with a subset also analyzed using the boron isotope 11b ph proxy observed relationships among sr ca u ca and 11b agree with model predictions indicating that the model accounts for the key features of the coral biomineralization process by calibrating to instrumental temperature records we show that sr u captures 93 of mean annual temperature variability 26 30 c and has a standard deviation of prediction of 0 5 c compared to 1 c using sr ca alone the sr u thermometer may offer significantly improved reliability for reconstructing past ocean temperatures from coral skeletons

experimental determination of factors controlling u ca of aragonite precipitated from seawater implications for interpreting coral skeleton abstract the u ca ratio of aragonite coral skeleton exhibits coherent patterns of seasonal and interannual variability in field sampled corals and those grown in controlled culture experiments strong correlations have been found between coral skeleton u ca and water temperature ph carbonate ion concentration and salinity however the mechanism s underlying these different correlations remain unclear we performed abiogenic precipitation experiments designed to evaluate the sensitivity of u partitioning between aragonite and seawater to temperature ph and the concentration of carbonate ion in seawater aragonite was precipitated from seawater by addition of carbonate alkalinity at rates set to maintain stable carbonate chemistry during precipitation experiments were conducted at 20 40 c with ph 7 8 9 0 and carbonate ion concentrations of 600 2600 mol kg 1 u ca ratios of the bulk precipitate and fluid were determined by inductively coupled plasma mass spectrometry our results show that the u ca ratio of aragonite precipitated from seawater decreases with increasing carbonate ion concentration and is independent of ph and temperature we use these results as a framework to interpret the skeletal composition of coral aragonite precipitated from a calcifying fluid that is semi isolated from the external seawater environment accordingly coral u ca ratios are consistent with calcifying fluid carbonate ion concentrations that are several times greater than those of ambient seawater correlations between coral u ca ratios and seawater temperature carbonate chemistry and other environmental variables arise indirectly via the impacts of these variables on the carbonate ion concentration of the coral calcifying fluid

structural limitations in deriving accurate u series ages from calcitic cold water corals contrast with robust coral radiocarbon and mg ca systematics radiocarbon and uranium thorium dating results are presented from a genus of calcitic antarctic cold water octocorals family coralliidae which were collected from the marie byrd seamounts in the amundsen sea pacific sector of the southern ocean andwhich to date have not been investigated geochemically the geochronological results are set in contextwith solution and laser ablation basedelement ca ratios li b mg mn sr ba u th octocoral radiocarbon ages on living corals are in excellent agreement with modern ambient deep water 14c while multiple samples of individual fossil coral specimens yielded reproducible radiocarbon ages provided that local radiocarbon reservoir ages can be derived for a given time fossil amundsen sea octocorals should be reliably dateable by means of radiocarbon in contrast to the encouraging radiocarbon findings the uranium series data are more difficult to interpret the uranium concentration of these calcitic octocorals is an order of magnitude lower than in the aragonitic hexacorals that are conventionally used for geochronological investigations while modern and late holocene octocorals yield initial 234u in good agreement with modern seawater our results reveal preferential inward diffusion of dissolved alpha recoiled 234u and its impact on fossil coral 234u besides alpha recoil related 234u diffusion high resolution sampling of two fossil octocorals further demonstrates that diagenetic uraniummobility has offset apparent coral u series ages combined with the preferential alpha recoil 234u diffusion this process has prevented fossil octocorals from preserving a closed system u series calendar age for longer than a few thousand years moreover several corals investigated contain significant initial thorium which cannot be adequately corrected for because of an apparently variable initial 232th 230th our results demonstrate that calcitic cold water corals are unsuitable for reliable u series dating mg ca ratios within single octocoral specimens are internally strikingly homogeneous and appear promising in terms of their response to ambient temperature magnesium lithium ratios are significantly higher than usually observed in other deep marine calcifiers and for many of our studied corals are remarkably close to seawater compositions although this family of octocorals is unsuitable for glacial deep water 14c reconstructions our findings highlight some important differences between hexacoral aragonitic and octocoral calcitic biomineralisation calcitic octocorals could still be useful for trace element and some isotopic studies such as reconstruction of ambient deep water neodymium isotope composition or ph via boron isotopic measurements

palaeomagnetism of precambrian rocks in northern sweden and its correlation to radiometric data abstract a palaeomagnetic study has been performed on palaeo to mesoproterozoic basic intrusions and volcanic rocks from the fennoscandian shield in northern sweden three possibly four different generations of magnetizations were identified the oldest assigned to a svecofennian age 1 86 1 89 ga a second generation is related to the intrusion of granitoids of 1 80 1 76 ga in this geological event probably also the third group of directions has its origin these different magnetizations may indicate that there are at least two different generations of basic intrusions in northern sweden a fourth group of directions is isolated as overprints this magnetization is interpreted to be a subjotnian magnetization reflecting a previously unrecognized regional subjotnian metamorphic event in the northwestern part of the fennoscandian shield the drift history for the fennoscandian shield during the period 1 88 1 50 ga has been defined based on these new palaeomagnetic data

a new paradigm for δ18o in coral skeleton oxygen isotope fractionation response to biological kinetic effects abstract this study investigated the relative impact of temperature and light on oxygen isotope fractionation in the aragonite of the symbiotic coral acropora sp which was cultured under controlled conditions aragonite was randomly sampled and the oxygen isotopic composition 18o was analyzed at the micrometer scale measurements were collected from six cultured colonies using a factorial design of three temperatures 22 c 25 c and 28 c and two light intensities 200 and 400 mol photon m 2 s 1 observation of the newly formed skeletons revealed fibrous morphology the 18o distribution following a bin width of 0 25 in histograms was bimodal because the colonies were cultured under constant environmental conditions we suggest this bimodality in isotope distribution was caused by the diurnal cycle of 12 h light and 12 h dark that is necessary for coral health and to mimic natural conditions we assume that the two modal values correspond to the two fractionation end members present in daytime and nighttime fibers then we investigated the precipitation mechanism for each in contrast to a common assumption that the two fractionations are due to differences in ph created by more or less efficient ca2 pumping we demonstrate that the ph at the calcification site cannot explain the isotopic discrepancy between daytime and nighttime and conclude that aragonite precipitation does not obey classical thermodynamic rules we suggest that secretion of proteins by the calicoblastic layer different following the diurnal cycle can induce distinct biological kinetic processes we highlight the interplay of carbonic anhydrase ca and organic molecules to accelerate and facilitate the crystallization of coral aragonite only governed by coral metabolism

fashion and phases of late pleistocene aggradation and incision in the alaknanda river valley western himalaya india abstract we study the aggradation and incision of the alaknanda river valley during the late pleistocene and holocene the morphostratigraphy in the river valley at deoprayag shows the active riverbed a cut terrace and a fill terrace the sedimentary fabric of the fill terrace comprises four lithofacies representing 1 riverbed accretion 2 locally derived debris fan 3 the deposits of waning floods and 4 palaeoflood records the sedimentation style coupled with geochemical analysis and optically stimulated luminescence osl dating indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21 18 ka and 13 9 ka during these periods sediment supply was relatively higher incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient the cut terrace formed at 5 ka during a phase of stable climate and tectonic quiescence the palaeoflood records suggest wetter climate 200 300 yr ago when the floods originated in the upper catchment of the higher himalaya and in the relatively drier climate 1 2 ka when locally derived sediments from the lesser himalaya dominated flood deposits maximum and minimum limits of bedrock incision rate at deoprayag are 2 3 mm a and 1 4 mm a

palaeomagnetism of middle proterozoic basic intrusives in central sweden and the fennoscandian apparent polar wander path abstract palaeomagnetic results are presented from three sets of post svecokarelian intrusions in central sweden the first is a system of e w trending doleritic dykes including the large breven and hallefors dykes and with a probable emplacement age of c 1530 ma their original nrm is disturbed by later events but two magnetic directions group ew1 with decl 359 5 incl 6 2 95 8 2 n 35 and group ew 2 with decl 11 1 incl 51 3 95 10 1 n 14 have been isolated and give palaeopoles at 27 7 n 196 8 e and 61 7 n 176 1 e respectively the group ew1 direction is considered to represent the original emplacement nrm this is based on comparison with contemporary palaeomagnetic data from elsewhere in fennoscandia the second set comprises dolerites and quartzporphyries the tuna dykes age 1371 ma they present a stable magnetization with decl 14 8 incl 18 1 95 9 6 and a palaeopole at 21 1 n 180 4 e the third set studied are dolerites belonging to the dala and jamtland complexes of the central scandinavian dolerite group csdg age c 1250 1200 ma post jotnian they present well defined magnetic directions that give palaeopoles close to the equator around 155 e in agreement with other published palaeomagnetic csdg data however there are deviating results obtain from dolerites belonging to the dala complex of the csdg those deviating have a mean decl of 12 9 incl 1 4 95 18 1 n 5 which gives a palaeopole at 27 0 n 179 5 e situated within the area of the 1600 1500 ma poles results from three probably sweconorwegian c 1000 850 ma doleritic dykes are also presented the results obtained are compared with other contemporary palaeomagnetic poles from fennoscandia and a revised apparent polar wander path is presented and discussed

paleomagnetism of 2 44 ga mafic dykes in russian karelia eastern fennoscandian shield implications for continental reconstructions abstract results of a paleomagnetic study of paleoproterozoic dykes and archean host rocks in the eastern fennoscandian shield are reported here most of the dykes are related to ca 2440 ma layered intrusions and have isotopic ages between 2349 and 2476 ma the dykes form an extensive nw se and e w trending swarm the majority are unaltered gabbronorites which carry stable remanent magnetizations with multicomponent nature the high temperature remanence component d which is thought to represent the primary 2 44 ga magnetization of the dykes has a paleomagnetic pole at 20 s 278 8 e a95 6 0 n 11 sites another d like component d with shallower inclination vgp 9 6 n 256 2 e eight samples at one site from baked archean host rock may also represent the primary remanence of the dykes the commonest remanence component a records an extensive svecofennian partial overprint and is interpreted to be ca 1 84 ga old it yields a paleomagnetic pole at 52 6 n 226 8 e a95 2 7 n 23 the fourth component b has a paleopole at 53 9 n 169 6 e a95 6 3 n 16 and is inferred to be ca 1 75 ga on the basis of isotopic dating although ages of 2 1 1 3 and 0 3 ga are also possible baked contact tests for the 2 44 ga dykes are negative as shown by the occurrence of component d in archean host rocks beyond one dyke width it is proposed that the negative baked contact test indicates regional reheating and remagnetization of the archean basement at ca 2 44 ga ago due to the spatially vast occurrence of coeval 2 44 ga mafic dykes layered intrusions volcanics and granites in the area based on this hypothesis it is suggested that component d in the dykes may be primary and acquired at ca 2 44 ga ago the similarity of pole d with poles from coeval dykes and layered intrusions elsewhere in the karelian province and kola peninsula suggest that within the archean domain of the fennoscandian shield no large scale block movements have taken place since 2 44 ga at 2 44 ga the fennoscandian shield was located at the latitude of ca 30 s which is different to that at 1 84 and 1 75 ga when fennoscandia was located at the latitudes of ca 30 n a continental reconstruction based on pole d and the pole from the 2 45 ga matachewan dykes of the superior craton in laurentia places the kola peninsula adjacent to southern greenland reconstructions based on recent geological interpretations and a reconstruction yielding pole d are also discussed

geomorphic evolution of dehra dun nw himalaya tectonics and climatic coupling abstract the dehra dun is a good example of a piggyback basin formed from the growth of the siwalik hills two large rivers the ganga and the yamuna and their tributaries deposit a significant part of their sediment load in the dun before they enter the gangetic plains this work documents the geomorphic complexities and landform evolution of the dehra dun through geomorphic mapping and chronostratigraphic investigation of the incised fan sections lesser himalayan hills inner and outer dissected hills isolated hills proximal fan distal fan dip slope unit floodplains and terraces are the major geomorphic units identified in the area isolated hills of fan material ihf proximal fan pf and distal fan df are identified as fan surfaces from north to south of the valley the osl based chronology of the fan sediments suggests that the ihf is the oldest fan consisting of debris flow deposits with a maximum age of 43 ka coinciding with the precipitation minima the proximal fan consisting of sheet flow deposits represents the second phase of aggradation between 34 and 21 ka caused by shifting of deposition locus downstream triggered by high sediment supply that exceeded the transport capacity the distal fan was formed by braided river deposits during 20 11 ka coinciding with the deglacial period the ihf pf and df surfaces were abandoned by distinct incision phases during 40 35 20 17 and 11 4 ka respectively a minor phase of terrace deposition in dehra dun was documented during 3 2 ka our results thus show that the evolutionary history of the alluvial fans in dehra dun was primarily controlled by climatic forcing with tectonics playing a minimum role in terms of providing accommodation space and sediment production

sr ca sensitivity to aragonite saturation state in cultured subsamples from a single colony of coral mechanism of biomineralization during ocean acidification using a new and rapid nanosims based method we quantified the sensitivity of skeletal sr ca in coral to the aragonite saturation state of seawater sw skeletal sr ca is a common proxy for temperature while sw is a parameter that varied in the past ocean and is predicted to change with continued ocean acidification five adult branches of the surface coral stylophora pistillata were grown at different sw from 2 7 to 4 9 ph of 7 9 8 5 but at a constant temperature of 25 c despite a large range of growth parameters and a twofold range in calcification rates the average skeletal sr ca of coral exposed to each condition are within 1 2 of each other 2 std dev of the 5 means furthermore the average skeletal sr ca measured in this study agrees with the results of two previous coral culture experiments conducted at the same temperature but where sw was not controlled these results suggest that aragonite saturation has little or no influence on sr ca paleothermometry over the range of sw investigated combined with existing data for low sw conditions our results were used to elucidate the mechanisms controlling calcifying fluid acid base chemistry during coral biomineralization assuming that coral drive precipitation through alkalinity pumping our data suggest that this pumping occurs until the calcifying fluid reaches a target ph below a threshold sw bounded by 1 sw 2 4 however coral do not pump enough alkalinity to reach the target ph and instead pump a maximal but finite amount of alkalinity in this low sw regime calcifying fluid ph is expected to decrease with sw the interplay between these two alkalinity pumping regimes and external seawater composition explain the full range of observed sr ca sensitivity to sw and suggest that surface coral may become increasingly sensitive to ocean acidification below a threshold sw bounded by 1 sw 2 4

comparison of equatorial pacific sea surface temperature variability and trends with sr ca records from multiple corals coral sr ca is widely used to reconstruct past ocean temperatures however some studies report different sr ca temperature relationships for conspecifics on the same reef with profound implications for interpretation of reconstructed temperatures we assess whether these differences are attributable to small scale oceanographic variability or vital effects associated with coral calcification and quantify the effect of intercolony differences on temperature estimates and uncertainties sr ca records from four massive porites colonies growing on the east and west sides of jarvis island central equatorial pacific were compared with in situ logger temperatures spanning 2002 2012 in general sr ca captured the occurrence of interannual sea surface temperature events but their amplitude was not consistently recorded by any of the corals no long term trend was identified in the instrumental data yet sr ca of one coral implied a statistically significant cooling trend while that of its neighbor implied a warming trend slopes of sr ca temperature regressions from the four different colonies were within error but offsets in mean sr ca rendered the regressions statistically distinct assuming that these relationships represent the full range of sr ca temperature calibrations in jarvis porites we assessed how well sr ca of a nonliving coral with an unknown sr ca temperature relationship can constrain past temperatures our results indicate that standard error of prediction methods underestimate the actual error as we could not reliably reconstruct the amplitude or frequency of el nino southern oscillation events as large as 2 c our results underscore the importance of characterizing the full range of temperature sr ca relationships at each study site to estimate true error

palaeomagnetic geochronological and geochemical study of mesoproterozoic lakhna dykes in the bastar craton india implications for the mesoproterozoic supercontinent abstract palaeomagnetic analysis of the lakhna dykes bastar craton india yields a palaeopole at 36 6 n 132 8 e dp 12 4 dm 15 9 and the u pb zircon age obtained from one of the rhyolitic dykes is 1466 4 2 6 ma mswd 0 21 concordia age based on two analyses with identical pb u ages similar to previously published u pb ages major and trace element analyses of the lakhna dykes show shoshonitic and high k calc alkaline affinities consistent with a subduction related characteristics suggesting an active continental margin setting this is in keeping with the palaeo to mesoproterozoic tectonic environments in the eastern indian margin the new 1460 ma indian palaeopole was used to test possible palaeopositions of india within the mesoproterozoic supercontinent columbia of the four palaeomagnetically permissible reconstructions juxtaposing western india against south west baltica is geologically the most reliably constrained and best fitting model our preferred reconstruction implies a long palaeo to mesoproterozoic accretionary orogen stretching from south eastern laurentia through south western baltica to south eastern india breakup of india and baltica probably occurred in the late mesoproterozoic but additional constraints are needed

ph homeostasis during coral calcification in a free ocean co2 enrichment foce experiment heron island reef flat great barrier reef geochemical analyses 11b and sr ca are reported for the coral porites cylindrica grown within a free ocean carbon enrichment foce experiment conducted on the heron island reef flat great barrier reef for a 6 mo period from june to early december 2010 the foce experiment was designed to simulate the effects of co2 driven acidification predicted to occur by the end of this century scenario rcp4 5 while simultaneously maintaining the exposure of corals to natural variations in their environment under in situ conditions analyses of skeletal growth measured from extension rates and skeletal density showed no systematic differences between low ph foce treatments ph 0 05 to 0 25 units below ambient and present day controls ph 0 for calcification rates or the ph of the calcifying fluid phcf the latter was derived from boron isotopic compositions 11b of the coral skeleton furthermore individual nubbins exhibited near constant 11b compositions along their primary apical growth axes 0 02 phcf units regardless of the season or treatment thus under the highly dynamic conditions of the heron island reef flat p cylindrica up regulated the ph of its calcifying fluid phcf 8 4 8 6 with each nubbin having near constant phcf values independent of the large natural seasonal fluctuations of the reef flat waters ph 7 7 to 8 3 or the superimposed foce treatments this newly discovered phenomenon of ph homeostasis during calcification indicates that coral living in highly dynamic environments exert strong physiological controls on the carbonate chemistry of their calcifying fluid implying a high degree of resilience to ocean acidification within the investigated ranges

the long life of samba connection in columbia a paleomagnetic study of the 1535 ma mucajai complex northern amazonian craton brazil abstract in recent years there has been a significant increase in the paleomagnetic data of the amazonian craton with important geodynamic and paleogeographic implications for the paleo mesoproterozoic columbia supercontinent a k a nuna hudsoland despite recent increase of paleomagnetic data for several other cratons in columbia its longevity and the geodynamic processes that resulted in its formation are not well known a paleomagnetic study was performed on rocks from the 1535 ma amg anorthosite mangerite rapakivi granite mucajai complex located in the roraima state brazil in the northern portion of the amazonian craton the guiana shield thermal and af treatments revealed northwestern southeastern directions with upward downward inclinations for samples from twelve sites this characteristic remanent magnetization is mainly carried by ti poor magnetite and in a lesser amount by hematite site mean directions were combined with previous results obtained for three other sites from the mucajai complex producing the dual polarity mean direction dm 132 2 im 35 4 n 15 95 12 7 k 10 0 and a paleomagnetic pole located at 0 1 e 38 2 s a95 12 6 k 10 2 the mucajai pole favours the samba south america baltica link in a configuration formed by amazonia and baltica in columbia also there is geological and paleomagnetic evidence that the juxtaposition of baltica and laurentia at 1 76 1 26 ga forms the core of columbia the present paleomagnetic data predict a long life 1 78 1 43 ga samba connection forming part of the core of the supercontinent

geochemical perspectives on coral mineralization corals open an exceptional window into many phenomena of geological geochemical climatic and paleontological interest from the paleozoic to the present corals provide some of the finest high resolution archives of marine conditions corals are likewise exceptional for chronometric purposes and even the terrestrial 14c timescale has now been calibrated against coral 230th 234u corals also represent a testing ground for basic ideas about mineralogy and geochemistry the shapes sizes and organization of skeletal crystals have been attributed to factors as diverse as mineral supersaturation levels and organic mediation of crystal growth the coupling between calcification and photosynthesis in symbiotic corals is likewise attributed to everything from photosynthetic alkalinization of the water to efforts by the coral to prevent photosynthetic alkalinization corals also leave a significant geochemical imprint on the oceans their aragonite skeletons accept about 10 times more strontium than does calcite hence the proportion of marine aragonite precipitation affects the oceanic chemical balance biological carbonates represent the biosphere s largest carbon reservoir hence calcareous organisms affect the ocean s ph co2 content and ultimately global temperatures through the greenhouse gas connection finally corals present some geochemical puzzles for ecology and conservation how do symbiotic corals obtain nutrients in some of the most nutrient deficient parts of the planet are global geochemical changes partially responsible for the widespread declines in coral reefs during recent decades we will address many of these issues but will concentrate on coral skeletal structure and calcification mechanism these topics bear most directly on the biomineralization process and generally affect the choice of skeletal materials and analytical techniques used in geochemical investigations the coral reef is probably the planet s most spectacular biomineralization product these grand and complex ecosystems build on the accumulated skeletal debris of countless generations of organisms especially calcareous algae and symbiotic

late quaternary holocene landscape evolution of a monsoon influenced high himalayan valley gori ganga nanda devi ne garhwal the garhwal himalaya provides an excellent natural laboratory in which to examine landscape evolution in a monsoon influenced high mountain environment geomorphic and sedimentological analysis and 10be cosmogenic radionuclide crn surface exposure dating of moraines fans and river and strath terraces in the gori ganga valley of nanda devi ne garhwal indicate that fans and river terraces developed rapidly by debris flow and flood processes during periods of deglaciation these phases of high sediment transfer occurred at 1 2 4 5 and 7 8 ka fan incision rates subsequent to major times of resedimentation after each glacial advance are between 19 and 57 mm year this contrasts with bedrock incision rates based on mid holocene strath terraces of 5 mm year these rates indicate that despite episodes of rapid denudation and resedimentation linked to glacial activity in this region the background rates of denudation are similar to those for other regions of the himalaya averaging several millimeters per year furthermore these data show the importance of climatic controls on landscape evolution and suggest a strong monsoonal control on the dynamics of earth surface processes in this region

compositional and morphological features of aragonite precipitated experimentally from seawater and biogenically by corals abstract the morphology and composition of abiogenic synthetic aragonites precipitated experimentally from seawater and the aragonite accreted by scleractinian corals were characterized at the micron and nano scale the synthetic aragonites precipitated from supersaturated seawater solutions as spherulites typically 20 100 m in diameter with aggregates of sub micron granular materials occupying their centers and elongate fibrous needles radiating out to the edge using sr isotope spikes the formation of the central granular material was shown to be associated with high fluid ph and saturation state whereas needle growth occurred at lower ph and saturation state the granular aggregates have significantly higher mg ca and ba ca ratios than the surrounding fibers two types of crystals are identified in the coral skeleton aggregates of sub micron granular material and bundles of elongate fibrous crystals that radiate out from the aggregates the granular materials are found in centers of calcification and in fine bands that transect the fiber bundles they have significantly higher mg ca and ba ca ratios than the surrounding fibers the observed relationship between seawater saturation state and crystal morphology and composition in the synthetic aragonites was used as a framework to interpret observations of the coral skeleton we propose that coral skeletal growth can be viewed as a cyclical process driven by changes in the saturation state of the coral s calcifying fluids when saturation state is high granular crystals precipitate at the tips of the existing skeletal elements forming the centers of calcification as the saturation state decreases aragonitic fibres grow in bundles that radiate out from the centers of calcification

twentieth century warming of the tropical atlantic captured by sr u paleothermometry coral skeletons are valuable archives of past ocean conditions however interpretation of coral paleotemperature records is confounded by uncertainties associated with single element ratio thermometers including sr ca a new approach sr u uses u ca to constrain the influence of rayleigh fractionation on sr ca decarlo et al 2016 here we build on the initial pacific porites sr u calibration to include multiple atlantic and pacific coral genera from multiple coral reef locations spanning a temperature range of 23 15 30 12 c accounting for the wintertime growth cessation of one bermuda coral we show that sr u is strongly correlated with the average water temperature at each location r2 0 91 p 0 001 n 19 we applied the multi species spatial calibration between sr u and temperature to reconstruct a 96 year long temperature record at mona island puerto rico using a coral not included in the calibration average sr u derived temperature for the period 1900 1996 is within 0 12 c of the average instrumental temperature at this site and captures the 20th century warming trend of 0 06 c per decade sr u also captures the timing of multi year variability but with higher amplitude than implied by the instrumental data mean sr u temperatures and patterns of multi year variability were replicated in a second coral in the same grid box conversely sr ca records from the same two corals were inconsistent with each other and failed to capture absolute sea temperatures timing of multi year variability or the 20th century warming trend our results suggest that coral sr u paleothermometry is a promising new tool for reconstruction of past ocean temperatures

palaeomagnetism and the siljan impact structure central sweden summary the siljan impact structure diameter c 52 km located in central sweden is considered the largest meteorite crater in western europe the time of impact has been estimated to be 368 ma from ar ar dating of an impact melt a palaeomagnetic study of rocks from inside and outside the impact structure has been carried out with the aim of identifying natural remanent magnetizations nrms related to the impact event primary magnetizations are partly preserved within the impact area however the directions of these original magnetizations are disturbed due to tectonic movements related to the impact three different directions of magnetizations not recognized elsewhere were identified within the central part of the structure these three magnetizations are defined in order of increasing coercivity hc and blocking temperature tb the origin of a high hc chemical remanent magnetization crm c of late palaeozoic time carried by haematite can be interpreted as due to oxidation caused by circulating meteoric water in cracks and fractures caused by the impact another component b identified in a lower temperature range 40d 580dc is probably carried by magnetite in pseudotachylite this magnetization is considered as a thermal remanent magnetization while in other rocks its pre tectonic character and occurrence also in the low coercivity range implies a shock remanent origin the palaeomagnetic pole for this remanence corresponds to a silurian devonian age which gives an age of impact which is not very diffirent from that estimated by radiometric data a third low hc and tb component a is interpreted to be a crm carried by slowly growing goethite the direction of this crm implies it to be a recent post impact magnetization

paleomagnetism of the north american precambrian a look at the data base more than half of the approximately 650 paleopoles reported from all precambrian cratons have been obtained from north america the observations have spurred a proliferation of apparent polar wander paths to support different hypotheses for the tectonic evolution of the continent many of the reasons for this development can be traced to the inadequacy of the data base with its average of only 1 6 poles 10 ma 1 as compared to 7 poles 10 1 ma for the last 300 ma even when it is assumed that a primary pole has been derived from each rock unit sampled the total number of primary poles excluding the 900 1200 ma interval yields an average of only 0 4 pole 10 ma 1 an inspection of the data base shows a non systematic sampling of a non continuous fragmented paleomagnetic record with gaps as large as tens and even hundreds of ma more importantly a search through the literature reveals that very few poles have an age known to better than 50 ma and for many poles the age bracket could be as large as a few hundreds of ma this is partly owing to the fact that radiometric and paleomagnetic sites rarely originate from the same localities it is shown that this limited data base with all its deficiencies and uncertainties cannot be used to support certain hypotheses or for the drawing of a meaningful apparent polar path for the whole of the precambrian it appears that because of the enormous time scale precambrian paleomagnetism should rather be directed towards the construction of segments of polar paths such as those in the 900 1200 ma interval comparison of well dated contemporaneous segments from different parts or structural provinces could be used most effectively to delineate relative movements if any and reconstruct the mosaic of the past continent for certain time intervals one of the recent developments of precambrian paleomagnetism has been to show that the apparent pole did not remain constrained to the equatorial region but made several excursions into high latitudes

morphological and compositional changes in the skeletons of new coral recruits reared in acidified seawater insights into the biomineralization response to ocean acidification 1 we reared primary polyps new recruits of the common atlantic golf ball coral favia fragum for 8 days at 25 c in seawater with aragonite saturation states ranging from ambient 3 71 to strongly undersaturated 0 22 aragonite was accreted by all corals even those reared in strongly undersaturated seawater however significant delays in both the initiation of calcification and subsequent growth of the primary corallite occurred in corals reared in treatment tanks relative to those grown at ambient conditions in addition we observed progressive changes in the size shape orientation and composition of the aragonite crystals used to build the skeleton with increasing acidification densely packed bundles of fine aragonite needles gave way to a disordered aggregate of highly faceted rhombs the sr ca ratios of the crystals measured by sims ion microprobe increased by 13 and mg ca ratios decreased by 45 by comparing these variations in elemental ratios with results from rayleigh fractionation calculations we show that the observed changes in crystal morphology and composition are consistent with a 80 decrease in the amount of aragonite precipitated by the corals from each batch of calcifying fluid this suggests that the saturation state of fluid within the isolated calcifying compartment while maintained by the coral at levels well above that of the external seawater decreased systematically and significantly as the saturation state of the external seawater decreased the inability of the corals in acidified treatments to achieve the levels of calcifying fluid supersaturation that drive rapid crystal growth could reflect a limit in the amount of energy available for the proton pumping required for calcification if so then the future impact of ocean acidification on tropical coral ecosystems may depend on the ability of individuals or species to overcome this limitation and achieve the levels of calcifying fluid supersaturation required to ensure rapid growth

revisiting the paleomagnetism of the 1 476 ga st francois mountains igneous province missouri 1 a paleomagnetic investigation of the st francois mountains igneous province in southeastern missouri provides a key 1476 16 ma paleomagnetic pole for laurentia the pole 13 2 s 219 0 e dp 4 7 dm 8 0 is considered primary on the basis of positive conglomerate inverse baked contact and fold tests an analysis of 1470 1430 ma poles from laurentia highlights key differences between poles obtained from the belt supergroup electra lake gabbro and cratonic north america paleolatitudes based on the lower belt supergroup poles are enigmatic as two previous studies yielded a difference of 10 our new pole combined with an analysis of previous results favors the higher latitude interpretation for the lower belt supergroup paleolatitudes from the younger belt rocks indicate lower latitudes than coeval rocks from elsewhere in laurentia for which there has been no adequate explanation a comparison of the st francois mountain pole with similar age poles from baltica siberia and australia allow first order tests of proposed continental configurations paleomagnetic data from australia are compatible with proposed rodinia reconstructions whereas paleomagnetic data from baltica are not we are unable to rigorously test the alternative suggestion that places siberia against the western margin of laurentia due in part to large errors associated with siberian paleomagnetic data

sr ca and mg ca vital effects correlated with skeletal architecture in a scleractinian deep sea coral and the role of rayleigh fractionation deep sea corals are a new tool in paleoceanography with the potential to provide century long records of deep ocean change at sub decadal resolution complicating the reconstruction of past deep sea temperatures mg ca and sr ca paleothermometers in corals are also influenced by non environmental factors termed vital effects to determine the magnitude pattern and mechanism of vital effects we measure detailed collocated sr ca and mg ca ratios using a combination of micromilling and isotope dilution icp ms across skeletal features in recent samples of desmophyllum dianthus a scleractinian coral that grows in the near constant environment of the deep sea sr ca variability across skeletal features is less than 5 2 relative standard deviation and variability of sr ca within the optically dense central band composed of small and irregular aragonite crystals is significantly less than the surrounding skeleton the mean sr ca of the central band 10 6 0 1 mmol mol 2 standard error and that of the surrounding skeleton 10 58 0 09 mmol mol are statistically similar and agree well with the inorganic aragonite sr ca temperature relationship at the temperature of coral growth in the central band mg ca is greater than 3 mmol mol more than twice that of the surrounding skeleton a general result observed in the relative mg ca ratios of d dianthus collected from separate oceanographic locations this large vital effect corresponds to a 10 c signal when calibrated via surface coral mg ca temperature relationships and has the potential to complicate paleoreconstructions outside the central band mg ca ratios increase with decreasing sr ca we explain the correlated behavior of mg ca and sr ca outside the central band by rayleigh fractionation from a closed pool an explanation that has been proposed elsewhere but which is tested in this study by a simple and general relationship we constrain the initial solution and effective partition coefficients for a rayleigh process consistent with our accurate metal ca measurements a process other than rayleigh fractionation influences mg in the central band and our data constrain a number of possible mechanisms for the precipitation of this aragonite understanding the process affecting tracer behavior during coral biomineralization can help us better interpret paleoproxies in biogenic carbonates and lead to an improved deep sea paleothermometer

palaeomagnetic and rock magnetic investigations of the sipoo subjotnian quartz porphyry and diabase dykes southern fennoscandia abstract the sipoo quartz porphyry dyke swarm u pb zircon age 1 63 ga in southern finland carries an intermediate to high coercivity remanent magnetization a n d 22 2 i 1 8 k 34 2 95 13 3 n 5 dykes which is regarded as primary the sipoo diabase dykes emplaced slightly before the granite porphyries yield a highly scattered antiparallel direction a r d 198 0 i 6 5 k 6 2 95 40 1 n 4 dykes isolated in intermediate to high coercivities based on positive contact test results remanence a r is primary in the diabases the best preserved diabase dyke as determined by petrographic and bulk magnetization properties carries both the a r magnetization and the a n magnetization as a secondary component in some samples the most altered diabase dyke is almost completely overprinted by a n the overprinting has taken place as a result of hydrothermal alteration and formation of new magnetite during the emplacement of quartz porphyry dykes and rapakivi granite the quartz porphyries and diabases carry mixed sd and md magnetic grain sizes the large md grains being responsible for a relatively large present earth s field pef magnetization in addition a high coercivity magnetization b d 23 9 i 52 2 k 215 8 95 6 3 n 4 dykes presumably a chemical overprint has been isolated in the quartz porphyries the b magnetization is interpreted to be either an intermediate direction between a n and pef with no geological significance or to represent a separate reactivation of the crust at about 1 32 ga ago

an apparent vital effect of calcification rate on the sr ca temperature proxy in the reef coral montipora capitata 1 measuring the strontium to calcium ratio in coral skeletons reveals information on seawater temperatures during skeletal deposition but studies have shown additional variables may affect the ratio here we measured sr ca in the reef coral montipora capitata grown in six mesocosms continuously supplied with seawater from the adjacent reef flat three mesocosms were ambient controls and three had seawater chemistry simulating ocean acidification oa we found that sr ca was not affected by the oa treatment and neither was coral calcification for these small colonies larger colonies did show an oa effect the lack of oa effects allowed us to test the hypothesis that coral growth rate can affect sr ca using the natural range in calcification rates of the corals grown at the same temperature we found that sr ca was inversely related to calcification rate sr ca 9 385 0 0040 calcification rate using a previously published calibration curve for this species a 22 mg d 1 colony 1increase in calcification rate introduced a 1 c warmer temperature estimate with the 27 corals reporting temperatures ranging from 24 9 to 28 9 c with mean 26 6 0 9 c standard deviation our results lend support to hypotheses invoking kinetic processes and growth rate to explain vital effects on sr ca however uncertainty in the slope of the regression of sr ca on calcification and a low r squared value lead us to conclude that sr ca could still be a useful proxy in this species given sufficient replication or by including growth rate in the calibration

uplift and cooling magnetisation record in the bamble and telemark terranes sveconorwegian orogenic belt se norway and the grenville sveconorwegian loop article i nfo the 1100 ma sveconorwegian orogenic belt comprises allochthonous terranes juxtaposed by major fault zones and emplaced against and onto the south western margin of the fennoscandian shield to resolve the magnetic signature acquired during post orogenic uplift and cooling and evaluate wider correlations with the contemporaneous grenville belt of north america this study reports a regional palaeomagnetic study on a range of rock types from sectors of the medium high metamorphic grade bamble terrane 48 sites and 390 cores and the adjoining medium low grade telemark terrane 33 and 240 cores juxtaposed by an orogen parallel porsgrunn kristiansand fault zone with major vertical displacement magnetite and ilmeno hematites are magnetic carriers with the latter more significant in the higher metamorphic grades magnetic intensities are stronger in the higher grade terrane presumably due to the growth of metamorphic ferromagnets but are an order lower than values predicted for the lower continental crust and indicate that an additional mechanism is responsible for high magnetisations in deep crust anisotropy of magnetic susceptibility ams largely reflects the ne sw tectonic grain of the last stage of sveconorwegian ductile deformation the magnetisation record is filtered by excluding magnetisations possibly acquired during regional mesozoic dyke emplacement development of the permo carboniferous oslo rift and late proterozoic magmatism the remaining record is a dual polarity signature summarised by mean poles at 31 9 n 50 9 e n 191 components in the bamble terrane and at 34 2 n 58 9 e n 151 components in the telemark terrane however these means are non fisherian and embrace arcuate distributions of magnetic components acquired during protracted exhumation cooling of the orogen with the best defined parts

post jotnian basic intrusions in the fennoscandian shield and the break up of baltica from laurentia a palaeomagnetic and ams study abstract a palaeomagnetic and anisotropy of magnetic susceptibility ams study has been performed on dolerite sills of the central scandinavian dolerite group csdg in the fennoscandian shield the dolerites occur in four previously known complexes in central sweden and finland and from the results of this palaeomagnetic study another complex has been identified in northern sweden these complexes cover an area of at least 100 000 km2 and the palaeomagnetic data suggest a small difference in time between the intrusion of the dolerites the measurements of anisotropy of magnetic susceptibility reveal a magnetic fabric with almost horizontal foliation planes and lineations that indicate fairly uniform ca nw or se directed magma flows the dolerites of the csdg are geochemically rather uniform and have compositions typical of mantle derived melts formed in continental tensional settings in a palaeomagnetic reconstruction of baltica versus laurentia at ca 1 27 ga the two continents were joined with ne greenland attached to nw baltica ams data from a few dolerites and a basalt in ne greenland indicate magma flow directions that in the tectonic reconstruction are more or less parallel to the flow of the dolerites in sweden this may suggest a common magma source located at the reconstructed contact between baltica and laurentia both the dolerites in greenland and those in sweden are of tholeitic composition indicating an intraplate origin which supports the interpretation of joined continents at that time the tensional regime that is reflected by the huge sill complexes is in our interpretation related to the break up of baltica from laurentia at ca 1 27 ga ago

a reconstruction of subtropical western north pacific sst variability back to 1578 based on a porites coral sr ca record from the northern ryukyus japan we present a seasonal reconstruction of sea surface temperature sst from 1578 to 2008 based on a porites coral sr ca record from the northern ryukyus within the kuroshio southern recirculation gyre interannual sst anomalies are generally 0 5 c making sr ca derived sst reconstructions a challenging task replicate measurements along adjacent coral growth axes enabled by the laser ablation inductively coupled plasma mass spectrometry technique used here give evidence of rather large uncertainties nonetheless derived winter sst anomalies are significantly correlated with the western pacific atmospheric pattern which has a dominant influence on winter temperature in east asia annual mean ssts show interdecadal variations notably cold intervals between 1670 and 1700 during the maunder minimum mm and between 1766 and 1788 characterized by a negative phase of the north atlantic oscillation cold summers in 1783 and 1784 coincide with the long lasting laki eruption that had a profound impact on the northern hemisphere climate including the severe tenmei famine in japan the decades between 1855 and 1900 are significantly cooler than the first half of the twentieth century while those between 1700 and 1765 following the mm are warmer than average sst variability in the ryukyus is only marginally influenced by the pacific decadal oscillation so that external forcing remains the main driver of low frequency temperature changes however the close connection between the kuroshio extension ke and its recirculation gyre suggests that decadal sst anomalies associated with the ke front also impact the ryukyus and there is a possible additional role for feedback of the kuroshio oyashio variability to the large scale atmosphere at decadal timescale

quaternary glacial history of nw garhwal central himalayas a first account of the quaternary glacial history is presented for northwest garhwal central himalaya on the basis of sediments and landforms one glacial stage has been recognised this is called the bhagirathi glacial stage when extensive valley glaciers advanced down the bhagirathi valley to jhala 40 5 km from the snout of gangotri glacier the ela depression during this stage was ca 640 m the bhagirathi glacial stage is constrained by optically stimulated luminescence dates of ca 63 ka and 5 ka bp and this glaciation is considered equivalent to the last glaciation elsewhere in the world the maximum extent of ice occurred ca 63 ka bp this however does not correlate with the last glacial maximum for the northern hemisphere ice sheets 20 18 ka bp a series of sharp crested moraines are present between 1 to 3 km beyond the snouts of most of the present glaciers these moraines formed during the mid holocene 5 ka bp termed here the shivling glacial advance small moraines are inset into these and are dated at about 200 to 300 bp the bhujbas glacial advance ca 300 to 200 bp and considered equivalent to the little ice age in other parts of the world ela depressions of between 40 100 m and 20 60 m occurred during the shivling and bhujbas glacial advances respectively since the bhujbas glacial advance there has been progressive retreat of glaciers initially by downwasting and retreat and then by simple retreat this retreat has accelerated during the last few decades impressive paraglacial fans are associated with deglaciation representing very rapid resedimentation during and soon after ice retreat

crustal evolution of fennoscandia palaeomagnetic constraints abstract palaeomagnetic poles from fennoscandia ranging in age from archaean to tertiary are compiled and graded using a modified briden duff classification scale an new filtering technique is applied to select only the most reliable poles for analysis the filtering takes into account the following information 1 1 source block of rock unit 2 2 age of rock 3 3 age of magnetization component 4 4 scatter of palaeomagnetic directions 5 5 information from multicomponent analysis of natural remanent magnetization nrm 6 6 whether the pole considered belongs to a cluster or subcluster of poles 7 7 magnetic polarity and 8 8 the author s original assignment of results data are still insufficient for the drawing of separate apparent polar wander paths apwp for different blocks or cratons of fennoscandia treating fennoscandia as a single plate a new apwp from archaean to permian is constructed from the five previously drawn apwp loops or hairpins only one the jatulian loop 2200 2000 ma disappears in filtering the loops during 1925 1700 ma and during 1100 800 ma ago are linked to svecofennian and sveconorwegian orogenies respectively palaeomagnetic data support the concept that these orogenies took place episodically three distinct orogenic pulses early middle and late can be distinguished in the cluster plots of palaeopoles the drift history of fennoscandia from archaean to permian is presented during most of geological history fennoscandia has occupied low to moderate latitudes and undergone considerable latitudinal shifts and rotations the svecofennian and sveconorwegian orogenies have different kinematic characteristics during the svecofennian orogeny fennoscandia drifted slowly while rotating a large amount in an anticlockwise sense during the sveconorwegian orogeny it drifted rapidly and rotated first clockwise and then anticlockwise the most striking feature in the drift velocity curves is however the pronounced maxima in the latitudinal drift and rotation rates 9 cm yr and 0 8 ma respectively during the late subjotnian jotnian anorogenic magmatism and rifting phase 1450 1250 ma ago possibly reflecting the passage of fennoscandia across a thermal upwelling hotspot at equatorial latitudes the use of palaeomagnetism in delineating and dating movements between blocks is demonstrated with three examples from the polar profile area the northernmost section of the european geotraverse

compositional variability in a cold water scleractinian lophelia pertusa new insights into vital effects we analyzed sr ca and mg ca ratios in the thecal wall of lophelia pertusa a cold water coral using sims ion microprobe techniques the wall grows by simultaneous upward extension and outward thickening compositional variability displays similar trends along the upward and outward growth axes sr ca and mg ca ratios oscillate systematically and inversely the sensitivity of lophelia sr ca ratios to the annual temperature cycle 0 18 mmol mol 1 c is twice as strong as that exhibited by tropical reef corals and four times as strong as the temperature dependence of sr ca ratios of abiogenic aragonites precipitated experimentally from seawater a comparison of the skeletal composition of lophelia with results from precipitation calculations carried out using experimentally determined partition coefficients suggests that both temperature dependent element partitioning and seasonal changes in the mass fraction of aragonite precipitated from the calcifying fluid influence the composition of lophelia skeleton results from calculations that combine these effects reproduce both the exaggerated amplitude of the sr ca and mg ca oscillations and the inverse relationship between sr ca and mg ca ratios

seawater nutrient and carbonate ion concentrations recorded as p ca ba ca and u ca in the deep sea coral desmophyllum dianthus as paleoceanographic archives deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating but have not been fully investigated for geochemical reconstructions of past ocean conditions here we assess the utility of skeletal p ca ba ca and u ca in the deep sea coral d dianthus as proxies of dissolved phosphate remineralized at shallow depths dissolved barium trace element with silicate type distribution and carbonate ion concentrations respectively measurements of these proxies in globally distributed d dianthus specimens show clear dependence on corresponding seawater properties linear regression fits of mean coral element ca ratios against seawater properties yield the equations p cacoral lmol mol 0 6 0 1 p casw lmol mol 23 18 r 2 0 6 n 16 and ba cacoral lmol mol 1 4 0 3 ba casw lmol mol 0 2 r 2 0 6 n 17 no significant relationship is observed between the residuals of each regression and seawater temperature salinity pressure ph or carbonate ion concentrations suggesting that these variables were not significant secondary dependencies of these proxies four d dianthus specimens growing at locations withoarag 6 0 6 displayed markedly depleted p ca compared to the regression based on the remaining samples a behavior attributed to an undersaturation effect these corals were excluded from the calibration coral u ca correlates with seawater carbonate ion u cacoral lmol mol 0 016 0 003 co 2 3 lmol kg 3 2 0 3 r 2 0 6 n 17 the residuals of the u ca calibration are not significantly related to temperature salinity or pressure scatter about the linear calibration lines is attributed to imperfect spatialtemporal matches between the selected globally distributed specimens and available water column chemical data and potentially to unresolved additional effects the uncertainties of these initial proxy calibration regressions predict that dissolved phosphate could be reconstructed to 0 4 lmol kg for 1 3 1 9 lmol kg phosphate and dissolved ba to 19 nmol kg for 41 82 nmol kg basw carbonate ion concentration derived from u ca has an uncertainty of 31lmol kg for 60 120 lmol kg co 2 3

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