major storm periods and climate forcing in the western mediterranean during the late holocene abstract big storm events represent a major risk for populations and infrastructures settled on coastal lowlands in the western mediterranean where human societies colonized and occupied the coastal areas since the ancient times the variability of storm activity for the past three millennia was investigated with a multi proxy sedimentological and geochemical study from a lagoonal sequence mappings of the geochemistry and magnetic susceptibility of detrital sources in the watershed of the lagoon and from the coastal barriers were undertaken in order to track the terrestrial or coastal marine origin of sediments deposited into the lagoon the multi proxy analysis shows that coarser material low magnetic susceptibility and high strontium content characterize the sedimentological signature of the paleostorm levels identified in the lagoonal sequence a comparison with north atlantic and western mediterranean paleoclimate proxies shows that the phases of high storm activity occurred during cold periods suggesting a climatically controlled mechanism for the occurrence of these storm periods besides an in phase storm activity pattern is found between the western mediterranean and northern europe spectral analyses performed on the sr content revealed a new 270 year solar driven pattern of storm cyclicity for the last 3000 years this 270 year cycle defines a succession of ten major storm periods sp with a mean duration of 96 54 yr periods of higher storm activity are recorded from 680 to 560 cal yr bc sp10 end of the iron age cold period from 140 to 820 cal yr ad sp7 to sp5 with a climax of storminess between 400 and 800 cal yr ad dark ages cold period and from 1230 to 1800 cal yr ad sp3 to sp1 little ice age periods of low storm activity occurred from 560 cal yr bc to 140 cal yr ad sp9 and sp8 roman warm period and from 820 to 1230 cal yr ad sp4 medieval warm period

a thousand year speleothem proxy record of north atlantic climate from scotland luminescent organic matter in stalagmites may form annual bands allowing growth rate to be precisely determined stalagmite growth rate is controlled by precipitation so annual bands can be used to derive long precipitation records a continuously banded stalagmite from a cave in nw scotland was used to provide a 1100 year high resolution record of precipitation the location of the cave means that precipitation is closely linked to the north atlantic oscillation for which a record is also derived this suggests that changes in the north atlantic oscillation state was an important control on european climate over the past millennium

aeolian sediment reconstructions from the scottish outer hebrides late holocene storminess and the role of the north atlantic oscillation northern europe can be strongly influenced by winter storms driven by the north atlantic oscillation nao with a positive nao index associated with greater storminess in northern europe however palaeoclimate reconstructions have suggested that the nao storminess relationship observed during the instrumental period is not consistent with the relationship over the last millennium especially during the little ice age lia when it has been suggested that enhanced storminess occurred during a phase of persistent negative nao to assess this relationship over a longer time period a storminess reconstruction from an nao sensitive area the outer hebrides is compared with late holocene nao reconstructions the patterns of storminess are inferred from aeolian sand deposits within two ombrotrophic peat bogs with multiple cores and two locations used to distinguish the storminess signal from intra site variability and local factors the results suggest storminess increased after 1000 cal yrs bp with higher storminess during the medieval climate anomaly mca than the lia supporting the hypothesis that the nao storminess relationship was consistent with the instrumental period however the shift from a predominantly negative to positive nao at c 2000 cal yrs bp preceded the increased storminess by 1000 years we suggest that the long term trends in storminess were caused by insolation changes while oceanic forcing may have influenced millennial variability

deformation and magnetization of the hudson valley eastern new york results of a study of calcite twinning and anisotropy of magnetic remanence in the onondaga limestone abstract results of a study of calcite twin analysis and anisotropy of anhysteretic remanent magnetization aarm for the onondaga limestone in the hudson valley fold and thrust belt hvb raise questions about the deformation history of this area and the nature of aarm two bedding parallel shortening directions are inferred from calcite twinning one normal to hvb fold axes nw se to ene wsw and the other at high angles to this direction nne ssw to n s two hypotheses are put forward to explain the inconsistent shortening direction 1 even during the initial stages of folding and thrusting in the hvb deformation was three dimensional in character 2 the hvb developed synchronous with main phase alleghanian deformation aarm results are consistent with the magnetic anisotropy being in part caused by the deformation associated with folding and thrusting this is a surprising result because the magnetization is presumably of diagenetic origin and it was acquired after folding

evidence for a two phase palmer land event from crosscutting structural relationships and emplacement timing of the lassiter coast intrusive suite antarctic peninsula implications for mid cretaceous southern ocean plate configuration 1 new analysis of the relationships between geological structural data and radiometric ages for the lassiter coast intrusive suite indicate that the collisional mid cretaceous palmer land event orogeny in the antarctic peninsula has had two kinematic phases forming an intersection orocline one of which can be related to cretaceous southern ocean plate motions both are compressional phases along the eastern palmer land shear zone phase 1 occurred at 107 ma with a principal paleostrain axis of 341 and is best expressed in southern palmer land although evident elsewhere on the antarctic peninsula phase 2 occurred at 103 ma with a principal paleostrain axis of 259 5 but is confined to between 68 s and 74 s a peak in lassiter coast intrusive suite magma emplacement rate was coeval with phase 1 whereas phase 2 may have coincided with a lull during phase 1 the allochthonous central and western domain terranes may have been transported to the gondwana margin represented by the para autochthonous eastern domain on board the phoenix plate or on board the south american plate the variable provenance indicators from the central and western terranes can be cited to support either or a combination of these scenarios the convergence direction evident from phase 2 structures cannot easily be reproduced in regional plate kinematic models this and the localized evidence for superposition of phase 2 structures on phase 1 structures suggests that phase 2 is unlikely to have occurred solely in response to changes in the kinematics of the large plates considered

el nino as a mediator of the solar influence on climate 1 using a climate model of intermediate complexity we simulate the response of the el nino southern oscillation enso system to solar and orbital forcing over the holocene solar forcing is reconstructed from radiocarbon production rate data using various scaling factors to account for the conflicting estimates of solar irradiance variability as estimates of the difference since the maunder minimum range from 0 05 to 0 5 of the solar constant we consider these two extreme scenarios along with the intermediate case of 0 2 we show that for large or moderate forcings the low pass filtered east west sea surface temperature gradient along the equator responds almost linearly to irradiance forcing with a short phase lag about a decade wavelet analysis shows a statistically significant enhancement of the century to millennial scale enso variability for even a moderate irradiance forcing in contrast the 0 05 case displays no such enhancement orbitally driven insolation forcing is found to produce a long term increase of enso variability from the early holocene onward in accordance with previous findings when both forcings are combined the superposition is approximately linear in the strong scaling case overall the sea surface temperature response is of the magnitude required and is persistent enough to induce important climatic perturbations worldwide the results suggest that enso may plausibly have acted as a mediator between the sun and the earth s climate a comparison to key holocene climate records from the northern hemisphere subtropics and midlatitudes shows support for this hypothesis

joint sets that enhance production from middle and upper devonian gas shales of the appalachian basin the marine middle and upper devonian section of the appalachian basin includes several black shale units that carry two regional joint sets j1 and j2 sets as observed in outcrop core and borehole images these joints formed close to or at peak burial depth as natural hydraulic fractures induced by abnormal fluid pressures generated during thermal maturation of organic matter when present together earlier j1 joints are crosscut by later j2 joints in outcrops of black shale on the foreland northwest side of the appalachian basin the east northeast trending j1 set is more closely spaced than the northwest striking j2 set however j2 joints are far more pervasive throughout the exposed devonian marine clastic section on both sides of the basin by geological coincidence the j1 set is nearly parallel the maximum compressive normal stress of the contemporary tectonic stress field shmax because the contemporary tectonic stress field favors the propagation of hydraulic fracture completions to the east northeast fracture stimulation from vertical wells intersects and drains j2 joints horizontal drilling and subsequent stimulation benefit from both joint sets by drilling in the north northwest south southeast directions horizontal wells cross and drain j1 joints whenever present then staged hydraulic fracture stimulations if necessary run east northeast i e parallel to the j1 set under the influence of the contemporary tectonic stress field thereby crosscutting and draining j2 joints

distinct phases of relative sea level changes in the central adriatic during the last 1500 years influence of climatic variations abstract we present a new sea level reconstruction for the past 1500 years based on biological indicators from the central adriatic islands biogenic littoral rims built by the coralline rhodophyte lithophyllum byssoides were found on the particularly exposed sites on the rocky coasts of the islands of vis ravnik and bisevo in croatia the presence of thick and well developed lithophyllum rims considered to be precise 10 cm sea level indicators points directly to the rising sea level environment biogenic rims were mapped measured and sampled for 14c dating the obtained results point to four phases of sea level changes the sea level was near stable from around 550 till 770 cal ad in the dark ages cold period dacp then during the medieval climate anomaly mca 770 till 1330 cal ad the sea level increased at a rate of 0 71 mm yr during the little ice age lia 1330 till 1640 cal ad it was near stable again later the sea level started to rise at a much higher rate particularly during the current warm period cwp these data were compared with local predictions derived from a glacio hydro isostatic models associated with the last glacial cycle if the isostatic eustatic component is separated this area seems to have almost stable tectonic conditions during the past 1500 years our results show that the large algal rims most likely grew during near stable sea level conditions that occurred during two relatively colder periods in the past 1500 years they also reveal that well developed up to 1 8 m wide upper levels of algal rims were formed during 300 years of stabilisation throughout the lia

palaeoclimatological and palaeolimnological records from fossil midges and tree rings the role of the north atlantic oscillation in eastern finland through the medieval climate anomaly and little ice age abstract hydrological changes and air temperature variability are reconstructed from the sediments of lake pieni kauro eastern finland during the medieval climate anomaly mca and little ice age lia using transfer functions derived from midge insecta nematocera based calibration models the reconstructions are compared with a regional tree ring chronology and sediment physical properties are determined to track depositional changes an objective of the study is to examine the long term relationship between the north atlantic oscillation nao and climate temperature precipitation our results show that the mca was characterized by warm and dry summer conditions which were accompanied by changes in the sediment magnetic susceptibility values most likely representing major forest fires during the tree ring indicated mca megadrought however the midge based stream flow reconstruction shows increased values during the mca thus implying enhanced spring floods after snowy winters during the lia the tree ring data indicate that a generally wetter climate prevailed during summers but the stream flow reconstruction indicates less snowy winters in the terms of long term climatology the present results show support to the concept that the nao has a positive correlation between winter precipitation and annual temperature and a negative correlation between summer precipitation in eastern finland thus the results may serve as important background data for global change assessments

environmental controls on the late holocene carbonate sedimentation of a karstic lake in the middle atlas mountains lake afourgagh morocco the lake afourgagh sediment record and facies successions provide an outstanding example of environmentally controlled carbonate sedimentation afourgagh is a small shallow permanent lake located in the middle atlas mountains in morocco in a karstic context it is fed by ground waters that are relatively enriched in mg resulting from the leaching of the jurassic dolomitic bedrock of the catchment this eutrophic lake is episodically restricted and characterized by alkaline waters with a fluctuating high mg ca ratio the maximum extension of the holocene shoreline coincides with evidence of a lake stabilization level corresponding to the outflow of the lake through a wadi lakeshore terrace sediments deposited on an alluvial fan siltstone during the past ca 2500 cal yr bp comprise four main facies a littoral crust palaeosols palustrine silts and charophyte tufas which reflect different environments from the shoreline toward the deeper water in the more distal parts the charophyte tufas display a well expressed lamination punctuated by the development of microstromatolites on algae thalli the mineralogical composition of the carbonates is linked to the facies while the charophyte tufas are characterized by a relatively high content in aragonite in addition to low mg calcite the littoral crust is mainly composed of magnesite this pattern is related to the evolving chemistry of water due to the influence of charophyte proliferation during dry summers calcium carbonate precipitation on algae thalli both bioinduced and microbially mediated progressively induces an increase in the mg ca ratio of the lake water while the capillary evaporation of shallow ground waters causes precipitation of a magnesite precursor on the shoreline producing magnesite during early diagenesis this effect is characteristic of two episodes part of the roman warm period and the beginning of the dark age cold period the carbonate mineralogy of the different depositional sequences at afourgagh indicates lake level and water chemistry fluctuations under a climatic influence therefore among other regional records the lake afourgagh sedimentary record provides useful evidence for reconstructing these environmental changes

climate changes reconstructed from a glacial lake in high central asia over the past two millennia abstract climatic changes in arid central asia aca over the past two millennia have been widely concerned however less attention has been paid to those in the high central asia hca where the asian water tower nurtures the numerous oases by glacier and or snow melt here we present a new reconstruction of the temperature and precipitation change over the past two millennia based on grain size of a well dated glacial lake sediment core in the central of southern tianshan mountains the results show that the glacial lake catchment has experienced cold wet climate conditions during the dark age cold period 300 600 ad dacp and the little ice age 1300 1870 ad lia whereas warm dry conditions during the medieval warm period 700 1270 ad mwp integration of our results with those of previously published lake sediment records stalagmite 18o records ice core net accumulation rates tree ring based temperature reconstructions and mountain glacier activities suggest that there has a broadly similar hydroclimatic pattern over the hca areas on centennial time scale during the past two millennia comparison between hydroclimatic pattern of the hca and that of the aca areas suggests a prevailing warm dry and cold wet hydroclimatic pattern over the whole westerlies dominated central asia areas during the past two millennia we argue that the position and intensity of the westerlies which are closely related to the phase of the north atlantic oscillation nao and the strength of the siberian high pressure sh could have jointly modulated the late holocene central asia hydroclimatic changes

modes of climate variability synthesis and review of proxy based reconstructions through the holocene abstract modes of climate variability affect global and regional climates on different spatio temporal scales and they have important impacts on human activities and ecosystems as these modes are a useful tool for simplifying the understanding of the climate system it is crucial that we gain improved knowledge of their long term past evolution and interactions over time to contextualise their present and future behaviour we review the literature focused on proxy based reconstructions of modes of climate variability during the holocene i e the last 11 7 thousand years with a special emphasis on i proxy based reconstruction methods ii available proxy based reconstructions of the main modes of variability i e el nino southern oscillation pacific decadal variability atlantic multidecadal variability the north atlantic oscillation the southern annular mode and the indian ocean dipole iii major interactions between these modes and iv external forcing mechanisms related to the evolution of these modes this review shows that modes of variability can be reconstructed using proxy based records from a wide range of natural archives but these reconstructions are scarce beyond the last millennium partly due to the lack of robust chronologies with reduced dating uncertainties technical issues related to proxy calibration and difficulty elucidating their stationary impact or not on regional climates over time while for each mode the available reconstructions tend to agree at mutidecadal timescales they show notable disagreement on shorter timescales beyond the instrumental period the reviewed evidence suggests that the intrinsic variability of modes can be modulated by external forcing such as orbital solar volcanic and anthropogenic forcing the review also highlights some modes experience higher variability over the instrumental period which is partly ascribed to anthropogenic forcing these features stress the paramount importance of further studying their past variations using long climate proxy records for the progress of climate science

orocline timing through joint analysis insights from the ibero armorican arc abstract the timing and kinematics of oroclinal bending in the core of the ibero armorican arc iaa has recently been constrained using paleomagnetic data from the cantabrian zone in northern iberia this study analyzes the joint patterns present in rock units deposited pre syn and post oroclinal bending systematic changes in the orientations of tensional joint sets in superimposed stratigraphic units are interpreted to record the progressive stages of oroclinal bending in the core of the iaa time constrains for joint set development are constrained by the known ages of the bounding unconformities that limit the studied stratigraphic units joint azimuth variability in the pre orocline rocks neoproterozoic to pre upper carboniferous is comparable to the present arc curvature of the orocline about 180 the joints in the syn orocline rocks upper pennsylvanian or stephanian 304 to 299 ma show a lower azimuthal variability that is comparable to about 50 70 of the total curvature seen in pre orocline rocks finally post orocline rocks permian contain joints that have uniform azimuths for each set across the entirety of the present day arc together these spatially and temporally distinct joint sets suggest that rotations in the cantabrian zone took place in the upper pennsylvanian during a ca 10 ma time period which agrees well with previous paleomagnetic arguments the data also provides supporting evidence for oroclinal bending by rotation around vertical axes of an initially linear or nearly linear orogenic belt and finally these data highlight the potential power in using tectonic joint sets for constraining thrust belt kinematics in curved orogenic systems when unconformity bounded stratigraphic sequences are present that are coeval with orocline development

holocene climate variability of the norwegian atlantic current during high and low solar insolation forcing 1 a high resolution sediment core from the voring plateau has been studied to document the centennial to millennial variability of the surface water conditions during the holocene climate optimum hco and the late holocene period lhp in order to evaluate the effects of solar insolation on surface ocean climatology quantitative august summer sea surface temperatures sssts with a time resolution of 2 40 years are reconstructed by using three different diatom transfer function methods spectral and scale space methods are applied to the records to explore the variability present in the time series at different time scales the ssst development in core md95 2011 shows a delayed response to northern hemisphere maximum summer insolation at 11 000 years b p the record shows the maximum ssst of the hco to be from 7 3 to 8 9 kyr b p which implies that the site was located in the regional warm water pool removed from the oceanic fronts and arctic waters superimposed on the general cooling trend are higher frequency variabilities at time scales of 80 120 210 320 320 640 and 640 1280 years the climate variations at the time scale of 320 640 years are documented both for periods of high and low solar orbital insolation we found evidence that the submillennial scale mode of variability 640 900 years in ssst evident during the lhp is directly associated with varying solar forcing at the shorter scale of 260 450 years the ssst during the lhp displays a lagged response to solar forcing with a phase locked behavior indicating the existence of a feedback mechanism in the climate system triggered by variations in the solar constant as well as the role of the thermal inertia of the ocean the abruptness of the cooling events in the lhp especially pronounced during the onsets of the holocene cold period i approximately 2300 years b p and the little ice age approximately 550 years b p can be explained by a shutdown of deep convection in the nordic seas in response to negative solar insolation anomalies these cooling events are on the order of 1 5 c

hydroclimatic changes over the past 900 years documented by the sediments of tiewaike lake altai mountains northwestern china abstract the reconstruction of variations in effective moisture over the past millennium are important for assessing potential future climatic trends in environmentally sensitive arid central asia aca especially in the context of ongoing global warming however high resolution time series reflecting past moisture variability in the region are scarce thus preventing a full understanding of the hydroclimatic evolution here we present the results of multi proxy analysis of a sediment core spanning the past 900 years from tiewaike lake in the altai mountains northern xinjiang the climatic proxies measured include grain size organic matter and carbonate content c n ratio and the stable carbon isotope composition of bulk organic matter the results show that over the past 900 years the climatic evolution of the study area can be divided into distinct hydroclimatic phases the arid medieval climate anomaly mca 1090 1430 ad the humid little ice age lia 1430 1940 ad and the arid current warm period cwp 1940 2012 ad during the lia the water level at tiewaike lake was overall higher than during the other climatic intervals in addition the lia climate was unstable and characterized by six intervals with the occurrence of heavy precipitation events on a multi decadal timescale a humid unstable climate during the lia is also suggested by climatic records from adjacent regions our results support the view that over the past millennium on a multi centennial timescale the moisture variations in aca were generally out of phase with those in the region affected by the asian summer monsoon the humid unstable lia climate in aca may have been associated with changes in the north atlantic oscillation nao index and or with variations in solar irradiance

coral derived western pacific tropical sea surface temperatures during the last millennium reconstructions of ocean temperatures prior to the industrial era serve to constrain natural climate variability on decadal to centennial timescales yet relatively few such observations are available from the west pacific warm pool here we present multiple coral based sea surface temperature reconstructions from yongle atoll in the south china sea over the last 1 250 years 762 2013 common era ce reconstructed coral sr ca sea surface temperatures indicate that the little ice age 1711 1817 ce period was 0 7 c cooler than the medieval climate anomaly 913 1132 ce and that late 20th century warming of the western pacific is likely unprecedented over the past millennium our findings suggest that the western pacific warm pool may have expanded contracted during the medieval climate anomaly little ice age leading to a strengthening weakening of the asian summer monsoon as recorded in chinese stalagmites

weathering effects on the magnetic properties of the milledgeville granite georgia abstract one of the major problems in paleomagnetic sampling of granites in the southeastern united states is finding fresh outcrop since most outcrops are weathered to some extent it is important to quantify the effect of weathering on the magnetic properties of individual samples the lake sinclair dam site near milledgeville georgia was chosen for this study where a very fresh stable granite outcrops in the excavated spillway lying immediately above is the weathered equivalent drilled samples were obtained from fresh and weathered portions at one outcrop and the remanent and induced magnetizations measured with af demagnetization it was possible to obtain the stable remanent directions exhibited by fresh samples from all weathered samples the induced and remanent magnetic behavior can be explained by maghemitization during weathering and the development of a secondary low oxidation magnetic phase and the reduction in domain size of primary magnetite

evolution of a large baltic beach ridge plain neudarss ne germany a continuous record of sea level and wind field variation since the homeric minimum

quantitative studies of weathering in saprolitized charnockites associated with a landslip zone at the porthimund dam india abstract studies on saprolitized charnockites associated with a landslip observed in the blue mountains in close proximity of the porthimund dam 11 22 e 76 34 30 n nilgiris district tamilnadu state south india are reported laboratory investigations of the geotechnical properties were carried out to evaluate the nature and degree of weathering quantitatively for estimating the soundness of the charnockites constituting the slip zone the results of per cent decomposed product of the crest scarp and toe portions of the slip denote positive correlations with porosity and compressibility and negative correlations against density wave velocity young s modulus compressive strength and tensile strength it is also seen that in the absence of the information on decomposed product weatherability could still be evaluated considering the per cent change of any physical parameter such studies should prove valuable in the mapping of weatherability zones and the assessment and determination of foundation conditions

investigating the maximum resolution of µxrf core scanners a 1800 year storminess reconstruction from the outer hebrides scotland uk micro x ray fluorescence xrf core scanning is capable of measuring the elemental composition of lake sediment at sub millimetre resolution but bioturbation and physical mixing may degrade envir

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

hydroclimatic changes in china and surroundings during the medieval climate anomaly and little ice age spatial patterns and possible mechanisms abstract investigating hydroclimatic changes during key periods such as the medieval climate anomaly mca 1000 1300 ad and the little ice age lia 1400 1900 ad is of fundamental importance for quantifying the responses of precipitation to greenhouse gas induced warming on regional and global scales this study synthesizes the most up to date and comprehensive proxy moisture precipitation records during the past 1000 years in china and surroundings the proxy data collected include 34 records from arid central asia aca and 37 records from monsoonal asia our results demonstrate a pattern of generally coherent regional moisture variations during the mca and lia in mid latitude asia north of 30 n monsoonal northern china north china and northeast china was generally wetter while aca northwest china and central asia was generally drier during the mca than in the lia a west east mode the boundary between wetter northern china and drier aca was roughly consistent with the modern summer monsoon boundary in monsoonal china to the east of 105 e the northern part was generally wetter while the southern part was generally drier during the mca than in the lia a north south mode with a boundary roughly along the huai river at about 34 n these spatial patterns of moisture precipitation variations are also identified by instrumental data during the past 50 years in order to understand the possible mechanisms related to the moisture variations during the mca and lia we investigate the major sst and atmospheric modes e g the el nino southern oscillation enso the atlantic multidecadal oscillation amo and the north atlantic oscillation nao which affect the moisture precipitation variations in the study region using both the instrumental data and the reconstructed time series it is found that the enso may play an important role in determining hydroclimatic variability over china and surroundings on a multi centennial time scale and that the foregoing spatial patterns could be attributed to the la nina like el nino like condition during the mca lia in addition amo and nao may also have their own contributions

paleomagnetic evidence for the continuity and independent movement of a distinct major crustal block in the southern appalachians the magnetization of 22 granitic and gneissic southern appalachian rock units with estimated cooling ages of 415 250 m y has been determined included are 842 samples from 114 sites within 19 granites 100 sites and 3 gneisses 14 sites located in north carolina south carolina and georgia data for units which cooled to temperatures 20 000 km sup 2 in size a mean paleopole for this group with corrections for maximum tilt estimates exhibits good precision but has a paleosite latitude of approx 10 sup 0 n without tilt correction the paleopole for group b still exhibits an anomalous paleositemore latitude of approx 4 sup 0 n these data indicate that the group b block elberton sparta crustal block lying to the se has an apparent paleosite latitude corresponding to magnetization at a location to the north of the zone containing group a units less

magnetization of the austell gneiss northwest georgia piedmont the austell gneiss is located in the piedmont 16 km west of atlanta georgia and 8 km northwest of the brevard fault zone this metamorphosed granite gneiss lies refolded in the nose of the austell frolona antiform a doubly plunging structure of regional extent subsequent to intrusion the unit has undergone four episodes of deformation the first and second generation folds f1 and f2 are coaxial but not coplanar the two later fold events were less intense and have little effect on local outcrop patterns in the study area the age of the unit has been estimated to be greater than 325 m y but less than 365 m y the induced and remanent magnetic properties for at least six cores drilled at each of 10 sites within the austell gneiss have been determined the magnetic foliation for the unit is approximately parallel with field estimates for s1 foliation planes exhibited by mineral orientations within the body indicating post emplacement magnetic grain mobility the stable remanent magnetization exhibited by the body was therefore probably acquired during or slightly after the f1 or f2 deformational events as a result of cooling from metamorphic temperatures 600 c or alternatively from secondary magnetite grain nucleation and growth a paleopole position calculated for these data without structural correction 126 2 34 4 dp 6 6 dm 13 2 can be explained by magnetic acquisition in at least three possible geologic settings from simple to complex these are the following first since a large oval of confidence is observed for the unit and minor tilting can not be resolved the data may be explained by magnetization of the austell at its present site during cooling from metamorphic temperatures second a northwestward thrust event may have resulted in bringing the austell to its present location third the data can be explained by two major translational events the austell may have initially been magnetized and then moved to the northeast by transcurrent strike slip faulting 1000 km into juxtaposition with the southern appalachians followed by thrusting of the unit to the northwest to its present location in support of this last interpretation is the similarity between the paleopole for the austell and paleopoles determined for the maritime provinces of north america which were suggested to have moved 1500 km to the northeast during the mid to late paleozoic against such an interpretation is the lack of geologic evidence in support of large scale left lateral strike slip faulting in the southern appalachians

variations in the difference between mean sea level measured either side of cape hatteras and their relation to the north atlantic oscillation we consider the extent to which the difference in mean sea level msl measured on the north american atlantic coast either side of cape hatteras varies as a consequence of dynamical changes in the ocean caused by fluctuations in the north atlantic oscillation nao from analysis of tide gauge data we know that changes in msl difference and nao index are correlated on decadal to century timescales enabling a scale factor of msl difference change per unit change in nao index to be estimated changes in trend in the nao index have been small during the past few centuries when measured using windows of order 60 120 years therefore if the same scale factor applies through this period of time the corresponding changes in trend in msl difference for the past few centuries should also have been small it is suggested thereby that the sea level records for recent centuries obtained from salt marshes adjusted for long term vertical land movements should have essentially the same nao driven trends south and north of cape hatteras only differing due to contributions from other processes such as changes in the meridional overturning circulation or geophysical fingerprints the salt marsh data evidently support this interpretation within their uncertainties for the past few centuries and perhaps even for the past millennium recommendations are made on how greater insight might be obtained by acquiring more measurements and by improved modelling of the sea level response to wind along the shelf

deformation history of the nw salient of the eastern ghats mobile belt india abstract the eastern ghats mobile belt of india displays fold thrust belt structure with a prominent salient on its nw margin the salient consists of lathore nappe and turekela klippe that have overthrust the craton to nw the rocks of the nappes have undergone granulite facies metamorphism and multiple phases of folding corresponding to the eastern ghats orogeny prior to thrusting as a result the granulites along the thrust are retrograded to amphibolites and the axial traces of the folds have been truncated against the thrust plane the basal decollement of the fold thrust belt is represented by the terrane boundary shear zone that defines the tectonic margin between the craton and the mobile belt it occurs as a ductile thrust affecting the cratonic basement as well as the mobile belt suggesting that the basement did not behave as a rigid body during thrusting thus the study area is comparable with the caledonide fold thrust belt further two large lateral ramps namely khariar and paikamal lateral ramps have been developed on the decollement at the lithological contact between tonalite trondhjemite gneisses granite gneisses and the latetectonic potassic granites of the craton fault bend folds associate with these ramps too it is suggested that the salient structure of the fold thrust belt is the combined result of 1 lateral ramps on the decollement and 2 differential displacement along the sole thrust due to lateral variation in detachment strength

reconstruction of sea level pressure fields over the eastern north atlantic and europe back to 1500 spatially and temporally high resolution estimates of past natural climate variability are important to assess recent significant climate trends the mid latitude atmospheric circulation is the dominant factor for regional changes in temperature rainfall and other climatic variables here we present reconstructions of gridded monthly sea level pressure slp fields back to 1659 and seasonal reconstructions from 1500 1658 for the eastern north atlantic european region 30 w to 40 e 30 n to 70 n these were developed using principal component regression analysis based on the combination of early instrumental station series pressure temperature and precipitation and documentary proxy data from eurasian sites the relationships were derived over the 1901 1960 calibration period and verified over 1961 1990 under the assumption of stationarity in the statistical relationships a transfer function derived over the 1901 1990 period was used to reconstruct the 500 year large scale slp fields systematic quality testing indicated reliable winter reconstructions throughout the entire period lower skill was obtained for the other seasons although meaningful monthly reconstructions were available from around 1700 onwards when station pressure series became available the quality and the reconstructed slp fields for two exceptionally cold years 1573 1740 are discussed and climatologically interpreted an eof analysis of the 1500 1999 winter slp revealed firstly a zonal flow pattern with pronounced decadal to centenial time scale variations secondly a monopole pattern over northwest europe and thirdly a pattern modulating the meridional flow component over europe these 500 year slp reconstructions should be useful for modelling studies particulary for analyses of low frequency atmospheric variability and for circulation dynamics

century scale relative sea level changes in west greenland a plausibility study to assess contributions from the cryosphere and the ocean this paper interprets high resolution relative sea level rsl reconstructions obtained from recently deposited salt marsh sediments in greenland the primary aim of this study is to determine the relative contribution to the rsl observations from local to regional ice mass changes as well as density related steric variations in the adjacent ocean at sites in west greenland rsl rise slows from 3 mm yr to 0 mm yr at 400 years bp and is stable thereafter in south greenland a similar rsl slowdown is also observed but this occurs approximately 200 yrs later substantial contributions from oceanographic changes are ruled out as dominant drivers of the rsl slowdown in western greenland but could be more important at nanortalik model sensitivity tests indicate that the rsl data are not compatible with a dominant dynamic ice loss via the jakobshavn isbrae outlet glacier as the region of ice loss and the resulting sea level trends are too localised regional changes in ice thickness related to surface mass balance changes can explain the observed rsl signals but only if there is dominant mass loss during the period 400 years bp to present this conclusion is unaffected even when uncertainties in earth viscosity structure are taken into account however it is plausible that some of the rsl fall may be due to reduced ice growth at the onset of the little ice age a high resolution mass balance history of the greenland ice sheet over the past few millennia and the influence of lateral earth structure on predictions of rsl change are identified as priority areas of study in order to confidently separate local transient e g elastic and gravitational rsl changes from the long term viscous contribution associated primarily with deglacial changes

sensitivity of bunker cave to climatic forcings highlighted through multi annual monitoring of rain soil and dripwaters abstract the last two decades have seen a considerable increase in studies using speleothems as archives of past climate variability caves under study are now monitored for a wide range of environmental parameters and results placed in context with speleothem data the present study investigates trends from a seven year long monitoring of bunker cave northwestern germany in order to assess the hydraulic response and transfer time of meteoric water from the surface to the cave rain soil and dripwater were collected from august 2006 to august 2013 at a monthly to bimonthly resolution and their oxygen and hydrogen isotope composition was measured furthermore drip rates were quantified due to different drip characteristics annual mean values were calculated for the drip rates of each drip site correlations of the annual mean drip rate of each site with precipitation and infiltration demonstrate that the annual infiltration and thus the annual precipitation control the inter annual drip rate variability for all except one site the hydraulic response is not delayed on an annual basis all drip sites display identical long term trends which suggests a draining of a common karst reservoir over these seven years of monitoring correlations of soil and dripwater monthly 18o and d values with atmospheric temperature data reveal water transfer times of 3 months to reach a depth of 40 cm soilwater at site bw 2 and 4 months for 70 cm depth soilwater at site bw 1 finally the water reaches the cave chambers 15 to 30 m below land surface after ca 2 5 years consequently a temporal offset of 29 to 31 months ca 2 5 years between the hydraulic response time no time lag on annual basis and the water transfer time time lag of 29 to 31 months was found which is negligible with regard to bunker cave speleothems because of their slow growth rates here proxies recording precipitation infiltration and temperature are registered on a decadal scale variations in drip rate and thus precipitation and infiltration are recorded by 13c and mg ca ratios in speleothem calcite speleothem 18o values reflect both temperature and precipitation signals due to drip rate related fractionation processes we document that long term patterns in temperature and precipitation are recorded in dripwater patterns of bunker cave and that these are linked to the north atlantic oscillation nao

2700 years of mediterranean environmental change in central italy a synthesis of sedimentary and cultural records to interpret past impacts of climate on society abstract abrupt climate change in the past is thought to have disrupted societies by accelerating environmental degradation potentially leading to cultural collapse linking climate change directly to societal disruption is challenging because socioeconomic factors also play a large role with climate being secondary or sometimes inconsequential combining paleolimnologic historical and archaeological methods provides for a more secure basis for interpreting the past impacts of climate on society we present pollen non pollen palynomorph geochemical paleomagnetic and sedimentary data from a high resolution 2700 yr lake sediment core from central italy and compare these data with local historical documents and archeological surveys to reconstruct a record of environmental change in relation to socioeconomic history and climatic fluctuations here we document cases in which environmental change is strongly linked to changes in local land management practices in the absence of clear climatic change as well as examples when climate change appears to have been a strong catalyst that resulted in significant environmental change that impacted local communities during the imperial roman period despite a long period of stable mild climate and a large urban population in nearby rome our site shows only limited evidence for environmental degradation warm and mild climate during the medieval warm period on the other hand led to widespread deforestation and erosion the ability of the romans to utilize imported resources through an extensive trade network may have allowed for preservation of the environment near the roman capital whereas during medieval time the need to rely on local resources led to environmental degradation cool wet climate during the little ice age led to a breakdown in local land use practices widespread land abandonment and rapid reforestation our results present a high resolution regional case study that explores the effect of climate change on society for an under documented region of europe

anthropogenic and climatic impact on holocene sediment dynamics in se spain a review the climatic and anthropogenic control on holocene sediment dynamics was not well constrained for the western mediterranean basin the paucity of high resolution palaeoenvironmental records long hampered a detailed understanding of the human impact on erosion rates this paper analyses holocene sediment dynamics in the context of regional climatic conditions land cover and human occupation based on an extended compilation of recently published high resolution paleoenvironmental proxy data from both terrestrial and marine environments the palaeoenvironmental reconstruction identified four main aridification episodes a at 5600 4700 a4 4100 3400 a3 2800 2500 a2 and 1900 1300 1200 a1 cal bp most of the severe aridification phases were climatically induced not human driven and well correlated with a large dataset of paleoenvironmental records from the western mediterranean basin and north atlantic ocean the phases of enhanced aridity are generally associated with enhanced sediment dynamics independent of the intensity and type of human occupation in contrast wet climatic conditions are found to be associated with both high and low sediment dynamics dependent on the human impact on the environment the mid late phoenician phoenician ii republican rome civilizations and the christian reconquest are all associated with high human impact on the environment and high erosion rates are reported for the vera basin and ne spain despite the improved hydrological conditions human occupation is not necessarily associated with geomorphic instability as shown by the post argaric omeya and nazarene periods that are characterized by low erosion rates and geomorphic stability

structure of the kingston orocline in the appalachian fold thrust belt new york the trend of the post taconic appalachian fold thrust belt changes at the city of kingston in the new york recess to the southwest of kingston fold thrust structures trend northeast southwest whereas to the north of kingston fold thrust structures trend due north to north northeast this paper discusses the structural geometry and origin of this change in trend detailed mapping 1 9 600 suggests that the fold thrust belt in the vicinity of kingston can be divided into three structural domains northern central and southern in the northern domain megascopic folds are open significant faults do not intersect the present day ground surface ordovician strata below the taconic unconformity are not extensively thrust over post unconformity strata and shortening is less than 5 in the southern domain shortening across the fold thrust belt is 30 numerous faults intersect the ground surface and ordovician strata are significantly thrust over postunconformity strata in the central domain there are numerous accommodation faults there are locally two noncoaxial spaced cleavages and strike slip lineations overprint dip slip lineations on many slip surfaces to explain the contrasts between domains we suggest that the bend at kingston is an intersection orocline created when northeast southwest trending structures of the kittatiny shawangunk segment of the appalachian fold thrust belt overprinted and reoriented older north south trending structures of the hudson valley fold thrust belt calcite twin strain gauge measurements indicate that there was less than 2 penetrative tangential stretching accompanying the development of this orocline

five hundred years of gridded high resolution precipitation reconstructions over europe and the connection to large scale circulation we present seasonal precipitation reconstructions for european land areas 30 w to 40 e 30 71 n given on a 0 5 0 5 resolved grid covering the period 1500 1900 together with gridded reanalysis from 1901 to 2000 mitchell and jones 2005 principal component regression techniques were applied to develop this dataset a large variety of long instrumental precipitation series precipitation indices based on documentary evidence and natural proxies tree ring chronologies ice cores corals and a speleothem that are sensitive to precipitation signals were used as predictors transfer functions were derived over the 1901 1983 calibration period and applied to 1500 1900 in order to reconstruct the large scale precipitation fields over europe the performance quality estimation based on unresolved variance within the calibration period of the reconstructions varies over centuries seasons and space highest reconstructive skill was found for winter over central europe and the iberian peninsula precipitation variability over the last half millennium reveals both large interannual and decadal fluctuations applying running correlations we found major non stationarities in the relation between large scale circulation and regional precipitation for several periods during the last 500 years we identified key atmospheric modes for southern spain northern morocco and central europe as representations of two precipitation regimes using scaled composite analysis we show that precipitation extremes over central europe and southern spain are linked to distinct pressure patterns due to its high spatial and temporal resolution this dataset allows detailed studies of regional precipitation variability for all seasons impact studies on different time and space scales comparisons with high resolution climate models as well as analysis of connections with regional temperature reconstructions

interpreting drivers of change in fluvial archives of the western mediterranean a critical view abstract fluvial archives in particular late glacial to holocene floodplain records may provide valuable information regarding past environmental conditions and stages of landscape evolution in view of the high significance of floodplain dynamics for the development of entire landscapes the number of studies that have been performed on floodplain sediments remains comparatively low especially regarding the western mediterranean region however one of the reasons could be seen in the high complexity and diversity of processes and factors that control and influence fluvial activity that often hampers a straightforward interpretation of floodplain dynamics therefore a basic demand on fluvial archive research is to address the complexity of the factors that control the characteristics of fluvial sequences in order to provide a robust basis for their interpretation as a starting point for discussion this paper aims to give an overview of fluvial dynamic patterns in the western mediterranean for the last 15 ka in order to examine their relevance for palaeoenvironmental reconstructions the basis for this is provided by previous investigations on four different river systems in spain and northern africa the results of which are herein synthesized in order to propose a regional late pleistocene and holocene fluvial history for the western mediterranean realm basic results are related to alluvial floodplain deposits and visible features within them such as alluvial soils incision marks and aggradation phenomena since fluvial systems are open systems we discuss our findings against the background of different influencing factors that could modify fluvial architecture and may restrict palaeoenvironmental reconstructions a more comprehensive interpretation focuses on signals that are common to each of the studied river systems in this respect we critically discuss the customary nature of cumulative probability functions for the identification of regional flooding episodes and point out the benefits of a stratigraphy supported approach for characterizing regional floodplain dynamics finally three alluvial soil formation periods were found in all settings a first phase after 15 ka ending with the younger dryas event a second one from 7 to 5 ka with a break between 6 5 and 5 5 ka and a third phase between 3 and 2 ka these soil formation periods were interrupted and framed by fluvial dynamic phases accompanied by channel aggradation floodplain deposition floodplain erosion and or river incision in particular after 5 ka around 1 6 and at 1 ka and during the little ice age lia floodplain aggradation affected river systems in iberia and northern africa as well a cautious assessment of these results and extensive comparisons with secondary archive information prompts us to relate the aggradation periods with climate forcing by means of a supra regional aridification that effected large areas of the western mediterranean in contrast the three mentioned soil formation periods can be linked with landscape stability most probably triggered by favorable climate conditions in the western mediterranean apart from these large scale patterns we discuss the reliability of information emerging from floodplain records against the background of individualistic river behavior and self organization regarding future work we want to emphasize the great potential of yet rarely applied system oriented approaches that also attach importance to sub catchment dynamics as a link between catchment slopes and the main river floodplain

sedimentary response of lake el tobar spain to climate lake level changes after the maunder minimum lake level reconstructions from a littoral core in lake el tobar spain are presented for the last 350 years these are based on plant macrofossils and stable isotopes from lacustrine carbonates our data suggest five episodes of advance and regression of the shoreline coupled with changes in water retention in the lake a low lake level and high water renewal episode at ca ad 1650 1715 is indicated by oxidized facies with abundant remains from terrestrial marsh plant macrofossils and low d18o and d13c values a fluctuating lake level episode at ca ad 1715 1772 during changing climatic conditions in the little ice age lia caused periods of erosion and sediment deposition that intermittently blocked the lake outlet resulting in more positive d18o and d13c values the lake became progressively more closed with increased level in the wet years at the end of the lia ca ad 1772 1850 during the dalton minimum d13c values reached a minimum indicating low productivity but increased after this with development of submerged chara from ca ad 1850 to 1960 lake levels were high but are marked by changes in marsh communities mainly the shift from juncus to typha ca ad 1850 1960 predominance which indicates low and high levels respectively

early jointing in coal and black shale evidence for an appalachian wide stress field as a prelude to the alleghanian orogeny early ene striking joints present coordinates within both pennsylvanian coal and devonian black shale of the central and southern appalachians reflect an approximately rectilinear stress field with a dimension 1500 km this appalachian wide stress field awsf dates from the time of joint propagation when both the coal and shale were buried to the oil window during the 10 15 m y period straddling the pennsylvanian permian boundary the awsf was generated during the final assembly of pangea as a consequence of plate boundary tractions arising from late stage oblique convergence where maximum horizontal stress s h of the awsf was parallel to the direction of closure between gondwana and laurentia after closure the awsf persisted during dextral slip of peri gondwanan microcontinents when sh appears to have crosscut plate scale trans current faults at around 30 sup o following 10 m y of dextral slip during tightening of gondwana against laurentia the awsf was disrupted by local stress fields associated with thrusting on master basement decollements to produce the local orocline shaped alleghanian map pattern seen today

the fluvial record of climate change fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic base level and human complications field stratigraphic evidence is explored here at three time scales the later pleistocene the holocene and the historical and instrumental period new data from a range of field studies demonstrate that croll milankovitch forcing dansgaard oeschger and heinrich events enhanced monsoon circulation millennial to centennial scale climate variability within the holocene probably associated with solar forcing and deep ocean circulation and flood event variability in recent centuries can all be discerned in the fluvial record although very significant advances have been made in river system and climate change research in recent years the potential of fluvial palaeohydrology has yet to be fully realized to the detriment of climatology public health resource management and river engineering

significance of dextral reactivation of an e w transfer fault in the formation of the pennsylvania orocline central appalachians 1 three hypotheses for orocline development including 1 primary plate boundary shape 2 arc rotation and 3 arc overprinting were evaluated for the formation of the pennsylvania orocline maryland usa using foliation intersection inflection axes preserved within porphyroblasts fia the distribution and the timing of sequences of fia data measured from garnet porphyroblasts within the loch raven formation are statistically the same across the pennsylvania orocline suggesting that all subregions of the arc have experienced the same deformation history this may suggest that the geometry of the paleocontinental margin controlled the basic shape of this orocline however if the orocline is treated as three separate regions defined by the sw we ne trending portions of its slightly staircase shaped outline a much higher proportion of the nne ssw trending fias set ii are preserved in the w e trending region than those to either side this geometric relationship could have resulted from wnw ese directed bulk stress causing a zone of dextral shear along what is now the w e trending portion of this orogen it appears that what could have been an early formed w e trending sinistral transform shear zone was preferentially dextrally reactivated during the taconian orogeny

variability of the north atlantic oscillation over the past 5 200 years the north atlantic oscillation influences climate in the arctic region and northern europe reconstructions of circulation patterns associated with the north atlantic oscillation from a 5 200 year long lake sediment record suggest that the atmospheric circulation responded to significant transitions in northern hemisphere climate

solar modulation of north atlantic central water formation at multidecadal timescales during the late holocene article i nfo understanding natural climate variability in the north atlantic region is essential not only to assess the sensitivity of atmosphere ocean climate signal exchange and propagation but also to help distinguish between natural and anthropogenic climate change the north atlantic oscillation is one of the controlling modes in recent variability of atmosphere ocean linkages and ice freshwater fluxes between the polar and north atlantic ocean through these processes the nao influences water mass formation and the strength of the atlantic meridional overturning circulation and thereby variability in ocean heat transport however the impact of the nao as well as other forcing mechanisms on multidecadal timescales such as total solar irradiance on eastern north atlantic central water production central water circulation and climate signal propagation from high to low latitudes in the eastern subpolar and subtropical basins remains uncertain here we use a 1200 yr long benthic foraminiferal mg ca based temperature and oxygen isotope record from a 900 m deep sediment core off northwest africa to show that atmosphere ocean interactions in the eastern subpolar gyre are transferred at central water depth into the eastern boundary of the subtropical gyre further we link the variability of the nao over the past 165 yrs and solar irradiance late holocene and their control on subpolar mode water formation to the multidecadal variability observed at mid depth in the eastern subtropical gyre our results show that eastern north atlantic central waters cooled by up to 0 8 0 7 c and densities decreased by 0 3 0 2 during positive nao years and during minima in solar irradiance during the late holocene the presented records demonstrate the sensitivity of central water formation to enhanced atmospheric forcing and ice freshwater fluxes into the eastern subpolar gyre and the importance of central water circulation for cross gyre climate signal propagation during the late holocene 2011 elsevier b v all rights reserved

reconstruction of mid to late holocene winter temperatures in the skagerrak region using benthic foraminiferal mg ca and δ18o reconstruction of skagerrak deep water renewal is used to assess regional changes in winter thermal conditions over the past 6800 years changes in winter climate conditions from the skagerrak region are in turn linked to shifts in holocene large scale atmospheric circulation patterns prevailing over northern europe we use melonis barleeanus mg ca from two sediment cores in the central skagerrak to reconstruct temperature of skagerrak intermediate water representing the warm season temperature variability and deep water for monitoring skagerrak deep water renewal reflecting the winter temperature variability in addition m barleeanus 18o is used from the deeper core to reconstruct salinity also monitoring the deep water renewal our results show that the skagerrak deep water experienced phases of particularly enhanced renewal during the mid holocene reflecting severe winter conditions followed by a general shift to reduced renewal as a consequence of milder winter conditions over the north sea a

a reconstruction of extratropical indo pacific sea level pressure patterns during the medieval climate anomaly subtropical and extratropical proxy records of wind field sea level pressure slp temperature and hydrological anomalies from south africa australia new zealand patagonian south america and antarctica were used to reconstruct the indo pacific extratropical southern hemisphere sea level pressure anomaly slpa fields for the medieval climate anomaly mca 700 1350 ce and transition to the little ice age lia 1350 1450 ce the multivariate array of proxy data were simultaneously evaluated against global climate model output in order to identify climate state analogues that are most consistent with the majority of proxy data the mean slp and slp anomaly patterns derived from these analogues illustrate the evolution of low frequency changes in the extratropics the indo pacific extratropical mean climate state was dominated by a strong tropical interaction with antarctica emanating from 1 the eastern indian and south west pacific regions prior to 1100 ce then 2 the eastern pacific evolving to the central pacific la nina like pattern interacting with a ve sam to 1300 ce a relatively abrupt shift to ve sam and the central pacific el nino like pattern occurred at 1300 a poleward equatorward shift in the subtropical ridge occurred during the mca mca lia transition the hadley cell expansion in the australian and southwest pacific region together with the poleward shift of the zonal westerlies is contemporaneous with previously reported hadley cell expansion in the north pacific and atlantic regions and suggests that bipolar climate symmetry was a feature of the mca

a well verified multiproxy reconstruction of the winter north atlantic oscillation index since a d 1400 abstract a new well verified multiproxy reconstruction of the winter north atlantic oscillation nao index is described that can be used to examine the variability of the nao prior to twentieth century greenhouse forcing it covers the period a d 1400 1979 and successfully verifies against independent estimates of the winter nao index from european instrumental and noninstrumental data as far back as 1500 the best validation occurs at interannual timescales and the weakest at multidecadal periods this result is a significant improvement over previous proxy based estimates which often failed to verify prior to 1850 and is related to the use of an extended reconstruction model calibration period that reduced an apparent bias in selected proxies associated with the impact of anomalous twentieth century winter nao variability on climate teleconnections over north atlantic sector land areas although twentieth century nao variability is somewhat unusual comparable periods of persistent positive phase

structure and origin of the fleurieu and nackara arcs in the adelaide fold thrust belt south australia salient and recess development in the delamerian orogen abstract the regional map pattern of structural trends in the early paleozoic adelaide fold thrust belt of south australia resembles an upright letter s in general structures in the fold thrust belt verge toward the gawler craton to the west so the northern curve nackara arc of the s is a salient whereas the southern curve fleurieu arc is a recess the map view axial trace of the nackara arc coincides with the thickest portion of the adelaidean late proterozoic basin and the map view axial trace of the fleurieu arc coincides with the intersection between the adelaidean and kanmantoo cambrian basins our structural analysis of the adelaide fold thrust belt demonstrates that the cross sectional structural geometry of the nackara arc contrasts markedly with that of the fleurieu arc in the nackara arc the belt consists of open detachment folds that probably formed above an evaporite hosted decollement whereas in the fleurieu arc the belt consists of an imbricate fan of basement involved thrusts further the foreland edge of the nackara arc coincides with a blind ramp whose strike parallels fold axes of the arc whereas the foreland edge of the fleurieu arc coincides with emergent thrusts that cut obliquely across earlier formed folds of the arc in the transition region between the two arcs the fold thrust belt consists of an intensely sheared basal duplex overlain by open folds structural contrasts between the nackara and fleurieu arcs indicate that the two curves did not form in the same way we present a model for development of these curves based on a comparison of their structural features to those of curves in other fold thrust belts and based on previous studies of curve formation using sandbox analogs we suggest that curvature of the nackara arc reflects the control of basin stratigraphy on the width of a fold thrust belt while curvature of the fleurieu arc reflects oroclinal bending of the fold thrust belt when it impinged on the southeastern corner of the gawler craton our model explains the structural contrast between the two arcs and illustrates correlations between fold thrust belt curve formation and pre deformational basin geometry

human climate interactions in the central mediterranean region during the last millennia the laminated record of lake butrint albania lake butrint 39 47 n 20 1 e is a ca 21 m deep coastal lagoon located in sw albania where finely laminated sediments have been continuously deposited during the last millennia the multi proxy analysis sedimentology high resolution elemental geochemistry and pollen of a 12 m long sediment core supported by seven ams radiocarbon dates and 137cs dating enable a precise reconstruction of the environmental change that occurred in the central mediterranean region during the last 4 5 cal kyrs bp sediments consist of triplets of authigenic carbonates organic matter and clayey laminae fluctuations in the thickness and or presence of these different types of seasonal laminae indicate variations in water salinity organic productivity and runoff in the lake s catchment as a result of the complex interplay of tectonics anthropogenic forcing and climate variability the progradation of the pavllo river delta favoured by variable human activity from the nearby ancient city of butrint led to the progressive isolation of this hydrological system from the ionian sea the system evolved from an open bay to a restricted lagoon which is consistent with archaeological data an abrupt increase in mass wasting activity between 1515 and 1450 bc likely caused by nearby seismic activity led to the accumulation of 24 homogenites up to 17 cm thick they have been deposited during the onset of finely laminated sedimentation which indicates restricted anoxic bottom water conditions and higher salinity periods of maximum water salinity biological productivity and carbonate precipitation coincide with warmer intervals such as the early roman warm period rwp 500 bc 0 ad the medieval climate anomaly mca 800 1400 ad and recent times after 1800 ad conversely lower salinity and more oxic conditions with higher clastic input were recorded during 1400 500 bc the late roman and the early medieval periods 0 800 ad and during the little ice age 1400 1800 ad hydrological fluctuations recorded in butrint are in phase with most central and western mediterranean records and correlate with nao variability in contrast opposite hydrological patterns have been recorded in the eastern balkans and the levant during the last millennium emphasizing a complex spatial variability in the region phases of maximum settlement intensity in butrint roman late antique coincide with warmer and or stable climate periods 0 800 ad and mca respectively indicating a long term influence of climatic conditions on human activities the late holocene sedimentary record of lake butrint demonstrates the complex interplay of climate variability tectonics and human impact in the recent evolution of coastal mediterranean regions

ams nrm interferences in the deccan basalts toward an improved understanding of magnetic fabrics in flood basalts the evaluation of flow direction in volcanic rocks is among the most important applications of magnetic fabrics studies a statistically significant sample set of titanomagnetite bearing lava flows from the malwa plateau the northern part of the deccan traps in india has been investigated for a possible interference of induced and natural remanent magnetization nrm the nrm alters the scalar anisotropy of magnetic susceptibility ams parameter and the orientations of the ams principal magnetic axes which are crucial for the evaluation of the flow direction for cleaning of the nrm component the lava samples have been demagnetized by use of an alternating field af tumbling demagnetizer peak fields of 100 mt as previous studies have shown that static af demagnetization can bias the results samples with normal magnetic fabrics demonstrate a redistribution of their principal axes after the demagnetization the evaluated flow directions show a more differentiated flow pattern of the malwa area which seems to fit better into the regional geological setting in samples with inverse magnetic fabrics carrying a higher portion of single domain particles ams principal axes remain unchanged after the demagnetization indicating that these samples with high coercivity of magnetic carriers are not suitable for geological interpretations according to these results we propose that the ams measurements after tumbling demagnetization give a better reflection of the intrinsic anisotropy of magnetic carriers at least for samples with normal magnetic fabrics and therefore a more precise and better reflection of the actual mineral fabric

factors controlling slip lineation orientation on thrust fault planes abstract the presence of multiple sets of curved and or non coaxial slip lineations on a single fault surface suggests changing stress conditions during the movement history of the fault curved slip lineations suggest a progressive change in the stress field during a single displacement event whereas non coaxial slip lineations suggest periodic reactivation of a fault under different stress conditions if the direction of slip is assumed to reflect the direction of maximum shear stress acting on a pre existing fault changes in only the relative magnitudes of principal stresses acting on the thrust sheet are sufficient to cause changes in slip lineation orientation consequently curved and or non coaxial slip lineations simply may record temporal changes in principal stress magnitudes resulting from syntectonic erosion changes in tectonic stress magnitude and ramping of thrusts to shallower depths we illustrate that a decrease in overburden or an increase in the magnitude of tectonic stress results in a progressive up dip rotation of slip lineations on a fault surface a rotation which could be misinterpreted as indicating polyphase deformation caused by changes in regional displacement directions changes in pore pressure do not influence the trajectory of slip on a fault surface but rather affect the conditions governing the likelihood for slip to occur

reconstruction of temperature in the central alps during the past 2000 yr from a δ18o stalagmite record the precisely dated isotopic composition of a stalagmite from spannagel cave in the central alps is translated into a highly resolved record of temperature at high elevation during the past 2000 yr temperature maxima during the medieval warm period between 800 and 1300 ad are in average about 1 7 8c higher than the minima in the little ice age and similar to present day values the high correlation of this record to d 14 c suggests that solar variability was a major driver of climate in central europe during the past 2 millennia d 2005 elsevier b v all rights reserved

vegetation fire climate and human disturbance history in the southwestern mediterranean area during the late holocene detailed pollen charcoal isotope and magnetic susceptibility data from an alpine lake sediment core from sierra nevada southern spain record changes in vegetation fire history and lake sedimentation since ca 4100 cal yr bp the proxies studied record an arid period from ca 3800 to 3100 cal yr bp characterized by more xerophytic vegetation and lower lake levels a humid period is recorded between ca 3100 and 1850 cal yr bp which occurred in two steps 1 an increase in evergreen quercus between 3100 and 2500 cal yr bp indicating milder conditions than previously and 2 an increase in deciduous quercus and higher lake levels between ca 2500 and 1850 cal yr bp indicating a further increase in humidity and reduction in seasonal contrast humid maxima occurred during the roman humid period previously identified in other studies in the mediterranean region intensified fire activity at this time could be related to an increase in fuel load and or in human disturbance an arid period subsequently occurred between 1850 and 650 cal yr bp though a decrease in quercus and an increase in xerophytes the alternation of persistent north atlantic oscillation modes probably played an important role in controlling these humid arid cycles

deformation of the proterozoic somanpalli group pranhita godavari valley south india implication for a mesoproterozoic basin inversion abstract the proterozoic somanpalli group originally deposited in a nw se trending fault controlled basin in the pranhita godavari valley pg valley suffered contractional deformation as recorded in nw se trending large scale folds imbricate thrusts second order semibrittle shear zone and smaller folds faults and cleavage three distinct structural stages dominated respectively by folding thrusting and strike slip faulting in that order can be recognized from overprinting relationships in outcrops the local ene wsw fold axis azimuth and cleavage strike is related to variation in the original depositional strike controlled by e w transfer faults rejuvenated as sinistral strike slip zones during the main contractional deformation a late extensional event possibly occurring during the upper proterozoic or mesozoic gondwana has been superimposed locally on the earlier fabric of the fold thrust belt the nw se trending folds and thrusts in the somanpalli group demonstrate the presence of a hitherto unrecognised compressional regime records of which occur in a 200 km stretch along the eastern margin of the pg valley the somanpalli group may be correlated with the mesoproterozoic pakhal group 1350 ma since the former is overlain by grossly undeformed and unmetamorphosed rocks of the neoproterozoic sullavai group a mesoproterozoic basin inversion in this region is suggested

pollen based palaeoclimate reconstructions over long glacial interglacial timescales methodological tests based on the holocene and mis 5d c deposits at sokli northern finland palaeoclimatic reconstructions over long glacial interglacial timescales present major methodological challenges as calibration methods based on modern climate and vegetation patterns may yield biased reconstructions from non analogue palaeoclimates such as severely continental glacial periods in this work we present pollen based summer temperature reconstructions based on holocene and early weichselian marine isotope stages mis 5d c deposits at sokli northern finland we attempt to improve the robustness of reconstructions of continental palaeoclimates by using two calibration sets with one located in the region surrounding the fossil site and another in a more continental region in northwestern russia we assess the reliability of the reconstructions by estimating the compositional fit between fossil and calibration samples and by comparison with independent plant macrofossil based reconstructions we find the fossil samples to fit the extra regional high continentality calibration set better during the early holocene and mis 5d c especially in mis 5d c however even the high continentality calibration set fits the fossil samples poorly compared to the fit achieved in the mid and late holocene thus our results highlight the problem of finding applicable calibration data for pre holocene periods we finally discuss the relative strengths and vulnerabilities of different calibration methods in reconstruction of non analogue palaeoclimates copyright 2013 john wiley sons ltd

pliocene climate variability northern annular mode in models and tree ring data the northern annular mode nam and its regional expression the north atlantic oscillation nao are the primary interannual oscillatory systems in the northern hemisphere in the modern climate nam has been linked with a number of weather extremes including large terrestrial temperature increases and extreme snowfalls its connection to climate is more controversial although a change in its behaviour between 1970 and 2000 coincided with rapid temperature increases in the northern hemisphere the north atlantic and nordic seas are a key component in pliocene climate showing the largest increases from modern sea surface temperature to understand these changes and the ability of climate models to reproduce them we must consider simulations of the nam here we show that existing mid pliocene simulations exhibit large changes to the mean state and variability in the north atlantic and a significant dampening of the nao through sensitivity experiments this change is primarily attributed to the impact of the lowering of the rocky mountains as the timing of rocky mountains uplift is still disputed simulations of the north atlantic region contain significant uncertainty particularly relating to interannual variability and its climate feedbacks new high temporal resolution climate proxy data is required to test these model reconstructions here we report new annual resolution data and an analysis of climate variability from fossil tree rings these fossils from sites in the canadian arctic provide support for a strong north atlantic oscillation during the pliocene

centennial scale vegetation and north atlantic oscillation changes during the late holocene in the southern iberia high reso ce to lution pollen analysis charcoal non pollen palynomorphs and magnetic susceptibility have been analyzed in the sediment record of a peat bog in sierra nevada in southern iberia the study of these proxies provided the reconstruction of vegetation climate fire and human activity of the last 4500 cal yr bp a progressive trend towards aridification during the late holocene is observed in this record this trend is interrupted by millennial and centennial scale variability of relatively more humid and arid periods arid conditions are recorded between 4000 and 3100 cal yr bp being characterized by a decline in arboreal pollen and with a spike in magnetic susceptibility this is followed by a relatively humid period from 3100 to 1600 cal yr bp coinciding partially with the iberian roman humid period and is indicated by the increase of pinus and the decrease in xerophytic taxa the last 1500 cal yr bp are characterized by several centennial scale climatic oscillations generally arid conditions from 450 to 1300 ce depicted by a decrease in pinus and an increase in artemisia comprise the dark ages and the medieval climate anomaly since 1300 to 1850 ce pronounced oscillations occur between relatively humid and arid conditions four periods depicted by relatively higher pinus coinciding with the beginning and end of the little ice age are interrupted by three arid events characterized by an increase in artemisia these alternating arid and humid shifts could be explained by centennial scale changes in the north atlantic oscillation and solar activity

a 1600 yr seasonally resolved record of decadal scale flood variability from the austrian pre alps we present a record of extreme spring summer runoff events for the past 1600 yr preserved in the varved sediments of lake mondsee austrian pre alps combined sediment microfacies analyses and high resolution micro x ray fluorescence element scanning allow us to identify 157 detrital event layers deposited in spring summer and to discriminate between regional flood and local debris flow deposits higher spring summer flood activity with a mean event recurrence of 3 5 yr occurred in several well confined multidecadal episodes during the dark ages cold period and medieval time a d 450 480 590 640 700 750 and 1140 1170 as well as during the early little ice age lia a d 1300 1330 and 1480 1520 in contrast lowest spring summer flood activity with an event recurrence of only 30 100 yr is observed during the medieval climate anomaly a d 1180 1300 and the coldest interval of the lia a d 1600 1700 these findings indicate a complex relationship between temperature conditions and extreme hydro meteorological events and suggest that enhanced summer mediterranean cyclogenesis triggers large scale floods in the northeast alps during climatic transitions the lake mondsee data demonstrate the climatic sensitivity of spring summer floods and prove the potential of varved sediment records to investigate the impact of changing climate boundary conditions on seasonal flood activity for pre instrumental time

possible mesozoic age of ellenville zn pb cu ag deposit shawangunk mountains new york ore textures epithermal open space filling of permian structures of the alleghanian orogeny and largely postorogenic mineralization of the ellenville new york composite zn pb cu ag vein system provide permissive evidence for post permian mineralization isochron ages determined by 40ar 39ar laser fusion techniques for k bearing liquid inclusions in main stage quartz from the ellenville deposit additionally suggest a mesozoic time of mineralization associated with extensional formation of the newark basin the best 40ar 39ar total fusion age range is 165 30 to 193 35 ma the mesozoic 40ar 39ar age agrees with that of many other dated northern appalachian zn pb cu ag deposits with near matching lead isotope ratios and adds new evidence of jurassic tectonism and mineralization as an overprint to late paleozoic tectonism at least as far north as ellenville lat 41 43 n

relative sea level change in greenland during the last 700 yrs and ice sheet response to the little ice age this paper presents new evidence regarding relative sea level rsl changes and vertical land motions at three sites in greenland since 1300 a d a time interval that spans the later part of the medieval climate anomaly mca and the little ice age lia we observe rsl rise at two sites in central west greenland from c 0 80 0 20 m at c 1300 a d to c 0 20 m 0 25 m at c 1600 a d after which rsl slowed and then stabilised at a third site in south greenland we observe rsl rise from c 1 40 0 20 m at c 1400 a d until c 1750 a d after which rsl slowed and was stable during at least the latter part of the 20th century the c 1600 a d rsl slow down seen at the two former sites is surprising because it occurs during the lia when one might expect the ice sheet to be gaining mass and causing rsl to rise we interpret this rsl slowdown to indicate a period of enhanced regional mass loss from central west greenland since c 1600 a d and propose two hypotheses for this loss first a reduction in precipitation during cold and dry conditions and second higher air temperatures and increased peripheral surface melt of the ice sheet from this date onwards the latter hypothesis is compatible with a well established temperature seesaw between western greenland and northern europe and potentially a previously identified shift from a positive to generally more negative nao conditions around 1400 to 1600 a d our study shows how rsl data from greenland can provide constraints on the timing of ice sheet fluctuations in the last millennium and challenges the notion that during cold periods in northern europe the ice sheet in west greenland gained mass

labrador current variability over the last 2000 years the ice loaded labrador current lc is an important component of the western north atlantic circulation that influences the position and strength of the northern limb of the north atlantic current nac this flow of cold and fresh polar waters originating from the arctic has a marked impact on the north atlantic climate yet little is known about its variability beyond the instrumental period in this study we present the first sub decadal alkenone based 2000 year long sea surface temperature sst records from the western labrador sea a climatically crucial region at the boundary between the lc and the nac our results show a clear link between the lc strength and the northern annular mode nam with a stronger nam and a more vigorous lc during the medieval climate anomaly mca this suggests enhanced lc activity upon future global warming with implications for the atlantic meridional overturning circulation amoc

comparison of fry strain ellipse and ams ellipsoid trends to tectonic fabric trends in very low strain sandstone of the appalachian fold thrust belt abstract in moderately to highly strained sandstones both the long axis of the bedding parallel finite strain ellipse as calculated by the normalized fry method and the projection of the long axis of the ams ellipsoid on the plane of bedding align well with local structural grain trends of cleavage folds and faults this relationship implies that results of both 2d fry and ams analyses represent the local layer parallel tectonic strain component do both methods provide comparable results for very low strain sandstone e g

anisotropy of magnetic susceptibility sedimentological igneous and structural tectonic applications as was noted by graham 1954 anisotropy of magnetic susceptibility ams data has many applications to the study of geological processes this type of anisotropy expresses directional variation in the magnetization induced in a rock most notably in its iron oxides and especially in its magnetite and hematite the ams is commonly expressed by an ellipsoid of which the principal axes are k1 k2 and k3 from greatest to least this ellipsoid is generally interpreted in terms of the distribution and shape of grains of magnetic minerals in a rock although the ellipsoid determined depends also on magnetocrystalline anisotropy and on factors of instrumental technique ellwood et al in press 1987 the challenge for the geoscientist in analyzing ams data is first to identify the origin of the ams geometry then second to relate that geometry to the natural processes which produced the inferred or measured distribution of magnetic materials

offshore continuation of meguma terrane southwestern nova scotia eight short drill cores have been examined from the continental shelf southwest of nova scotia four cores recovered granitoid rocks of two types ilmenite bearing granitoid rocks petrographically and geochemically resemble granodiorites of the south mountain batholith and granites of the seal island pluton magnetite bearing granitoid rocks are also peraluminous but have no exact analogues onshore in nova scotia two cores recovered metamorphic rocks in a small area 50 km south of seal island one consits of chlorite muscovite quartz schist geochemically similar to rocks of the halifax formation the second sampled epidote chlorite quartz schist similar to metavolcanic rocks of the white rock formation one further core sampled quartzite and another sampled a metavolcanic rock possibly erratic the regional extent of these lithotypes can be inferred from gravity and aeromagnetic data regional gravity data suggest the presence of a large granite body off southwestern nova scotia in this area magneti

an archive of high resolution temperature reconstructions over the past 2 millennia high resolution temperature reconstructions typically annually to seasonally resolved have played a key role in understanding paleoclimate immediately prior to the beginning of the instrumental record especially when calibrated to form an extension of comparable instrumental data coverage global hemispheric and regional such calibration allows the information in the instrumental record to be quantitatively extended backward in time in an objective way enabling description of much longer term fluctuations in climate than possible with instrumental data alone although with significantly increased uncertainties inherent in proxy based reconstructions this data brief describes a newly integrated archive of nearly all the high resolution temperature reconstructions of the past 2 millennia included in noaa s national climatic data center from small regional to global scale which also have been recalibrated to a standard set of instrumental data examination of the spectral structure of the data is additionally provided

estimating long term sediment export using a seasonal rainfall dependent hydrological model in the glonn river basin germany in european catchments rainfall and overland flow trigger erosive processes that could result in soil detachment and transportation however estimation of both erosive rainfalls and sediment yields is very challenging especially in historical times when only precipitations at seasonal or annual scales are available this motivated us to develop a parsimonious hydroclimatological model asclim annual sediment climatological model for predicting catchment scale sediment yield when temporal and spatial high resolution precipitation data are not available the model was developed by using the annual data of suspended sediment yield from glonn basin 1981 1995 gauge of hohenkammer germany and seasonal rainfall data from a noaa data set the correlation coefficient between predicted and observed sediment yields was 0 94 and the efficiency index was 0 89 once parameterized the model was able to capture annual sediment yield variability better than the langbein schumm and the fournier index equations also based on limited sets of inputs the model holds potential for historical reconstruction of sediment yields in the glonn catchment assuming constant land cover and for simulating sediment fluxes from catchments with similar characteristics our application highlights the control of rainfall seasonality on sediment export and demonstrates that our sediment yield proxy could be considered as a good tool for the expectation and planning of soil conservation moreover considering that we used modeled data to reconstruct past sediment loss we could expect that using projected future rainfall data our proxy could be able to assess future scenarios

deformation history of the roanoke recess appalachians usa the evolution of the roanoke recess is controversial because agreement is lacking about the timing and continuity of deformation increments because it may or may not have behaved like an adjacent salient and recess because while many salients have been investigated few recesses have and because the role of blind thrusts is unclear to gain insight into these controversies we estimated shortening directions shortening magnitudes and relative timing in the recess from map scale folds outcrop scale stylolites and grain scale solution structures and twins the key results from combining these new data with previous work are as follows 1 the deformation history around the roanoke recess is most simply described as temporally continuous with deformation migrating northeastward while the primary shortening direction rotated counterclockwise from n directed to almost w directed 2 consequently the roanoke recess did not deform in the symmetrical manner of the adjacent pennsylvania salient nor with the two step history of the kingston recess further to the north in the appalachians 3 the timing and magnitude of shortening increments are sufficient to necessitate a blind thrust under the present surface rocks of the inner recess throughout the deformation history

mid holocene emergence of a low frequency millennial oscillation in western mediterranean climate implications for past dynamics of the north atlantic atmospheric westerlies the nature and tempo of holocene climate variability is examined in the record of forest vegetation from western mediterranean marine core md95 2043 episodes of forest decline occurred at 10 1 9 2 8 3 7 4 5 4 4 5 and 3 7 2 9 cal ka bp and between 1 9 cal ka bp and the top of the record 1 3 cal ka bp wavelet analysis confirms a 900 yr periodicity prior to and during the early holocene and the dominance of a 1750 yr periodicity after 6 cal ka bp the 900 yr periodicity has counterparts in numerous north atlantic and northern hemisphere palaeoclimate records and in solar irradiance proxies 14c and 10be and may relate to a sun climate connection during the early holocene comparisons between the md95 2043 forest record and strategically located records from morocco iceland norway and israel suggest that the 1750 yr mid to late holocene oscillation reflects shifts between a prevailing strong and weak state of the zonal flow with impacts similar to the positive and negative modes of th

holocene flood frequency across the central alps solar forcing and evidence for variations in north atlantic atmospheric circulation the frequency of large scale heavy precipitation events in the european alps is expected to undergo substantial changes with current climate change hence knowledge about the past natural variability of floods caused by heavy precipitation constitutes important input for climate projections we present a comprehensive holocene 10 000 years reconstruction of the flood frequency in the central european alps combining 15 lacustrine sediment records these records provide an extensive catalog of flood deposits which were generated by flood induced underflows delivering terrestrial material to the lake floors the multi archive approach allows suppressing local weather patterns such as thunderstorms from the obtained climate signal we reconstructed mainly late spring to fall events since ice cover and precipitation in form of snow in winter at high altitude study sites do inhibit the generation of flood layers we found that flood frequency was higher during cool periods coinciding with lows in solar activity in addition flood occurrence shows periodicities that are also observed in reconstructions of solar activity from 14 c and 10 be records 2500 3000 900 1200 as well as of about 710 500 350 208 suess cycle 150 104 and 87 gleissberg cycle years as atmospheric mechanism we propose an expansion shrinking of the hadley cell with increasing decreasing air temperature causing dry wet conditions in central europe during phases of high low solar activity furthermore differences between the flood patterns from the northern alps and the southern alps indicate changes in north atlantic circulation enhanced flood occurrence in the south compared to the north suggests a pronounced southward position of the westerlies and or blocking over the northern north atlantic hence resembling a negative nao state most distinct from 4 2 to 2 4 kyr bp and during the little ice age south alpine flood activity therefore provides a qualitative record of variations in a paleo nao pattern during the holocene additionally increased south alpine flood activity contrasts to low precipitation in tropical central america cariaco basin on the holocene and centennial time scale this observation is consistent with a holocene southward migration of the atlantic circulation system and hence of the itcz driven by decreasing summer insolation in the northern hemisphere as well as with shorter term fluctuations probably driven by solar activity

late holocene paleoenvironmental changes in northeast brazil recorded by organic matter in lacustrine sediments of lake boqueirao northeast brazil represents a key area in terms of holocene environmental changes in south america due to its distinct semi arid climate at near equatorial latitudes as well as to a wetter early and middle holocene paleoclimate in comparison with other south america regions which also experienced a reduced monsoon at that time we studied the lacustrine sediments of lake boqueirao which is located at 5 s latitude on the brazilian atlantic coast it is directly influenced by displacement of the intertropical convergence zone itcz a short 1 m core boqc0701 was collected at a 7 5 m water depth during a seismic survey organic matter om geochemical rock eval total organic carbon toc hydrogen index hi oxygen index oi and petrographical studies allowed us to distinguish five sedimentary intervals during the last 3 kyrs phase e 3000 to 2050 cal yr bp presents the largest toc hi and oi fluctuations in the entire core the most probable cause of these variations is a great instability in the lake level during this period phase d 2050 to 1830 cal yr bp is marked by an increase in sedimentation rate and a higher contribution from a well preserved om with an algal origin this was interpreted as a higher and more stable lake level during phase c 1830 to 1550 cal yrs bp low hi and high oi indicate the input of more oxidized degraded and detrital om reflecting a lower lake level in phase b 1550 to 1470 cal yr bp the om quality and quantity hi and toc indicate an algal contribution during phase a 1470 to 570 cal yr bp the high stability of the proxies may be due to a deep environment where om fluctuations are strongly buffered these changes in lake level can be compared with other tropical south america high resolution records a correspondence seems to exist between phases of low enso cool north atlantic ocean and boqueirao wet phases we did not encounter this same pattern during the last 1050 years during which the 1050 570 cal yrs bp interval was generally wet although probable fluctuations are buffered in our proxies while the north atlantic was warm mann et al 2009 a prolonged dryness occurred in lake boqueirao from 570 cal yrs bp until recent decades this phase corresponds to the little ice age characterized by a cooler north atlantic ocean mann et al 2009 these data indicate that the teleconnection pattern between the tropical atlantic enso and northeast brazil rainfalls has changed in the past

inter annual climate variability in europe during the oligocene icehouse abstract new sclerochronological data suggest that a variability comparable to the north atlantic oscillation nao was already present during the middle oligocene about 20 myr earlier than formerly assumed annual increment width data of long lived marine bivalves of oligocene 30 25 ma strata from central europe revealed a distinct quasi decadal climate variability modulated on 2 12 mainly 3 7 year cycles as in many other modern bivalves these periodic changes in shell growth were most likely related to changes in primary productivity which in turn were coupled to atmospheric circulation patterns stable carbon isotope values of the shells 13 c shell further corroborated the link between shell growth and food availability sub decal oscillations in the 3 7 year band in other annually resolved fossil archives were often interpreted as el nino southern oscillation enso cycles this possibility is discussed in the present study however combined shell derived proxy and numerical climate model data lend support to the interpretation of a nao like variability according to numerical climate models winter sea level pressure wslp and precipitation rate wpr across central europe during the oligocene exhibited a pattern similar to the modern nao the simulated nao index for the oligocene shows periodicities coherent with those revealed by the proxy data 2 5 6 years yet on shorter wavelengths than the modern nao biennial and 6 10 year cycles likely the different paleogeography and elevated atmospheric co 2 concentrations not only influenced the sea level pressure pattern but also the temporal variability of the nao precursor the present study represents the first attempt to characterize the inter annual climate variability in central europe during the oligocene and sets the basis for future studies on the early phase of the cenozoic icehouse climate state

palaeoclimate and palaeoceanographic conditions in the westernmost mediterranean over the last millennium an integrated organic and inorganic approach previous studies have revealed the excellence of the westernmost mediterranean records for reconstructing climate conditions over the last two millennia in particular inorganic and organic proxies have revealed a coherent signal of climate and oceanographic responses during this time here we compare and integrate both proxy records for reconstructing climate and oceanographic conditions with focus on the last millennium the higher temperatures indicated by lipid based proxies during the medieval climate anomaly mca are coincident with drier conditions indicated by inorganic proxies in contrast lower temperatures and humid conditions are indicated during the little ice age lia the industrial period was characterized by increasing humidity in comparison with the previous lia however a progressive aridification occurred since the second half of the twentieth century coexisting with a warming trend and higher contribution of c3 grasses proxy records are also interpreted to show atlantic water inflow at ad 1450 and 1950 and an intensification of the upwelling conditions coinciding with a prolonged positive north atlantic oscillation nao phase in the intervals ad 1000 1450 and 1960 1990 large scale oceanic atmospheric circulation patterns the nao and the atlantic meridional circulation and solar irradiance variations seem to have played the major key role during the last millennium together with anthropogenic contributions in the more recent record

geomorphologic and paleoclimatic evidence of holocene glaciation on mount olympus greece this study investigates the possibility of holocene glaciation on mount olympus greece with a respective local temperature precipitation equilibrium line altitude tp ela at c 2200m a s l based on geomorphologic and paleoclimatic evidence at present the local tp ela is situated above the mountain s summit c 2918 m a s l but permanent snowfields and ice bodies survive within megala kazania cirque between c 2400 and c 2300 m a s l because of the cirque s maritime setting that results from its close proximity c 18km to the aegean sea and of the local topographical controls the snow and ice bodies occupied a considerably larger area and attained a stabilization phase between ad 1960 and 1980 also manifested from aerial photographs a period characterized by increased winter precipitation pw with subsequent tp ela depression to c 2410m a s l mid to late 20th century pw and tp ela variations exhibit negative correlations with the winter north atlantic oscillation index naow at annual and multidecadal 30 years timescales late holocene ad 1680 1860 reconstructed summer mean temperatures were lower by ts 1 1 c in relation to the reference period between ad 1960 and 1980 and were also superimposed to negative naow phases thus bracketing this time interval as a favorable one to glacial formation and or advance millennial scale annual precipitation reconstructions at the hypothesized tp ela c 2200m a s l point the period between 8 and 4 kyr bp as another glacier friendly candidate the mid holocene rather simplistic sequence of potential glacial advance phase was disturbed by short lived cold climatic deteriorations well documented over the northern aegean region that may partly explain the multicrested shape of the highest c 2200 m a s l morainic complex of megala kazania cirque

reworked coccoliths as runoff proxy for the last 400 years the case of gaeta gulf central tyrrhenian sea central italy abstract we present the results of a high resolution study carried out on a shallow water sediment core recovered in the central tyrrhenian sea to reconstruct the runoff history of the catchment basin of volturno and garigliano rivers gulf of gaeta italy over the past 400 years we compared the abundance distribution pattern of reworked coccoliths to the surface runoff model simulation for the volturno and garigliano hydrographic river basins the global historical climatology network index the palmer drought severity index the tevere river discharge anomaly the average summer rainfall in southern italy and the reconstructed north atlantic oscillation signal this comparison suggested that the biotic signal of the reworked coccoliths may be used to detect climatic events from local to global scale the calcareous nannofossil assemblages as well as their diversity index are modulated by oscillation in solar activity where minima in solar activity correspond to minima calcareous nannofossil diversity and vice versa in particular the antiphase correlation between the abundance of reworked coccoliths and the north atlantic oscillation index which modulates winter precipitation suggests that this biotic index could be used as a reliable proxy to reconstruct the variations in the hydrographic basin runoff of the volturno and garigliano rivers in addition power spectral and wavelet analysis carried out on both signals documented the occurrence of climatic cycles of the duration of about 95 yr from 1900 ad upwards a turnover in the periodicity from 95 yr climatic cycles to 22 26 yr cycles occurred in the reworked coccoliths signal suggesting a strong control of solar forcing hale cycle over the last century

magnetic effects of maghemitization of oceanic crust both theoretical considerations and available experimental results indicate that magnetic effects of maghemitization are strongly dependent on the grain size of the originally unoxidized titanomagnetite maghemitization of single domain titanomagnetite results in a decrease in coercivity an increase in susceptibility and a large decrease in q ratio maghemitization of multidomain titanomagnetite results in an increase in coercivity a decrease in susceptibility and no large changes in q ratio single domain titanomagnetite is probably resistant to the development of a chemical remanent magnetization crm whereas multidomain titanomagnetite can acquire a crm during maghemitization the behavior of pseudo single domain titanomagnetite which is the main carrier of remanence in submarine extrusive rocks is investigated by comparing the magnetic properties of the french american mid ocean undersea study famous less than 0 1 m y old and the leg 37 3 5 m y old pillow basalts recovered from the mid atlantic ridge near 37 n combining electron microprobe analyses curie temperature measurements and cell edge determinations we find that the famous rocks are already oxidized z 0 38 possibly as a result of some high temperature maghemitization during cooling of the magma comparison with the more highly oxidized z 0 7 leg 37 pillow basalts indicates that low temperature maghemitization of such rocks does not result in appreciable changes of coercivity and susceptibility although the q ratio does decrease and crm seems to be acquired such a crm could account for the anomalously low magnetic inclinations observed at most of the leg 37 sites

paleomagnetism of carboniferous intrusions in north carolina paleomagnetic samples of two late paleozoic plutons were collected from the eastern piedmont province in north carolina results from the early carboniferous 326 27 m y lilesville pluton located in the carolina slate belt indicate a pole position similar to that of the stable north american craton for the lower carboniferous five sites inthis gabbro granite complex give a pole of 40 n 134 e 95 2 9 the late carboniferous 282 6 m y churchland pluton located in the charlotte belt gives a pole of 34 n 126 e 95 16 3 which correlates well with other north american poles for the late carboniferous observations made by kent and opdyke 1978 on rocks from the eastern edge of the northern appalachians suggest gross lateral displacement between the mid devonian and late carboniferous in the late paleozoic this paleomagnetic information from the eastern piedmont region implies that the area of the carolina slate belt and charlotte belt was associated with the north american platform for the entire carboniferous period the slate belt rocks although geologically a southern counterpart to some of the avalonian rocks from the northeastern edge of north america do not display a paleomagnetic history suggestive of great displacement

a euro mediterranean tree ring reconstruction of the winter nao index since 910 c e we develop a new reconstruction of the winter north atlantic oscillation nao index using a network of 97 euro mediterranean tree ring series the reconstruction covers the period 910 2018 c e making it the longest annually resolved estimate of winter nao variability available we use nested correlation weighted principal components regression and the maximum entropy bootstrap method to generate a 2400 member ensemble of reconstructions for estimating the final reconstruction and its quantile uncertainties extensive validation testing of the new reconstruction against data withheld from the calibration exercise demonstrates its skill the skill level of the new reconstruction is also an improvement over two nao reconstructions published earlier spectral analyses indicate that the new reconstruction behaves like a white noise process with intermittent band limited power suggesting that the winter nao is stochastically forced the white noise properties of our reconstruction are also shown to be consistent with the spectral properties of long instrumental nao indices extending back to 1781 and nao indices extracted from a large number of forced climate model runs covering the last millennium in contrast an annually resolved multi proxy nao reconstruction of comparable length based in part on speleothem data behaves more like externally forced red noise process which is inconsistent with our reconstruction long observations and forced model runs