evidence of saharan dust in upper pleistocene reworked palaeosols of north west sardinia italy palaeoenvironmental implications abstract a multi disciplinary approach was followed to investigate two thick palaeosolstrata that alternate with wind blown dominated deposits developed along thealghero coast north west sardinia italy optically stimulated luminescenceages reveal that both palaeosols were developed during cooler drier periods the rst one at around 70 ka marine isotope stage 4 and the latter around 50 ka marine isotope stage 3 in contrast the pedological features indicate that thepalaeosols underwent heavy weathering processes under warm humid to sub humid conditions characteristic of the sardinian climate during the lastinterglacial stage marine isotope stage 5e to reconcile this apparent datadiscrepancy a range of sedimentological and pedological analyses wereconducted these analyses reveal that the palaeosols possess a complexhistory with accumulation and weathering occurring during marine isotopestage 5e and erosion colluviation and nal deposition taking place during thefollowing cold stages thus even if these reddish palaeosols were last formedduring the glacial period the sediments building up these strata probablyrecord the climate of the last interglacial stage marine isotope stage 5e traceelement and x ray diffraction analyses together with scanning electronmicroscope images reveal the presence of saharan dust in the parentmaterial of the palaeosols however no evidence of any far travelled africandust has been observed in the marine isotope stage 4 3 aeolian deposits it ispossible to conclude that in the west mediterranean islands saharan dustinput even if of modest magnitude is preserved preferentially in soilsaccumulated and weathered during interglacial stages keywords marine isotopic stage mediterranean osl dating trace elementgeochemistry xrd analysis sedimentology 2012 59 917 938

provenance and formation of the red palaeosol and lithified terra rossa like infillings on the island of susak a high resolution and chronological approach abstract red palaeosol rp covering the carbonate basement exposed at the bottom of the loess section and lithified terra rossa like materials situated in cavities ltr1 and karstified fissures ltr2 in cretaceous limestones were investigated by means of high resolution approach to give a systematic and deeper palaeopedological insight into reddish materials and the exposed red palaeosols on the island of susak both selected geochemical indicators of weathering al si na k al and fed fet and provenance la ce as well as detailed mineralogical analysis clearly showed differences among ltr1 ltr2 and rp respectively ltr1 and ltr2 represent erosional remains of different soils that existed on the surface of the limestone bedrock prior to the formation of the rp ltr2 has the highest ztr zircon tourmaline rutile index index and contains bauxite minerals gibbsite and boehmite clays kaolinite and mixed layer clay minerals and haematite ltr2 bears characteristics of reworked bauxitic materials mixed with other soils that existed on the surface of the carbonate basement those materials might have been mixed and transported until they were captured in the karstified fissure and subsequently interlocked with calcite veins and lithified this might have happened from the eocene age on our attempt to resolve the age of ltr2 formation more precisely using palaeomagnetic investigations did not give unambiguous results because the extremely viscous behaviour of the ltr2 samples hinders the acquisition of a stable remanent magnetisation if we exclude the secondary calcite ltr1 bears typical mineralogical and geochemical characteristics e g fed fet ratio similar to those of istrian terra rossa insoluble residues of cretaceous limestone might have been the main parent materials for the ltr1 formation while the most likely additional fluxes influencing terra rossa formation on the island of susak were aeolian dust and flysch the erosion remains ended in limestone cavities and were mixed with cm to dm sized angular and subangular limestone clasts and subsequently interlocked with calcite veins and lithified the investigated rp profile comprised the following mineral horizons bwb1 bwb2 bwb3 r the rp formed in a lithologically uniform material that dominantly presents a mixture of loess and partly remains of older soils e g rounded clay coatings not related to macrovoids that existed on the surface of the cretaceous limestone fed fet ratio in rp reflects a low degree of weathering of fe containing primary silicates therefore we can conclude that the rp does not fit a rather limited variation of selected fe oxide characteristics typical for terra rossa the investigated rp was classified independently of the overlying material the full name of the palaeosol that we classified is as follows hypereutric chromic cambisol episiltic endoloamic since no reversal of the emf was recorded in the rp we concluded that the rp formed during the brunhes epoch luminescence dating was applied to establish the age of the rp based on the acquired data we assume that the rp very likely formed during the penultimate interglacial ois7

the iron content of some red mediterranean soils from northeast spain and its pedogenic significance abstract alfisols cover 18 of the surface of the ne edge of the garraf massif se of barcelona catalonia most of these are mediterranean red soils some representative pedons especially over mesozoic limestones are discussed in this paper climate of the zone is littoral mediterranean mean temperature 16 c precipitation 650 mm pedoclimatic regimes are xeric and thermic vegetation is quercetum ilicis galloprovinciale horizon b is 5yr and 2 5yr in munsell hue with a phw of 7 2 to 8 6 all of them are base saturated and the majority recarbonated organic matter content is 2 5 some have an isohumic character the illuviation clay index ranges from 0 37 to 0 87 and the mean value of the illuviation fe index is 0 76 the nearly constant fed clay ratio indicates co illuviation values for fed are between 0 40 and 2 81 the mean feo is 0 057 and it ranges between 0 to 0 14 generally redness rating rr increases with fed values of fed fe1 vary from 0 22 to 0 82 and the mean is 0 54 rubefaction according to redness rating is moderate taxonomically calcic haploxeralfs predominate and are located at 50 70 m above sea level calcic palexeralfs at 70 80 m and again at 150 m and petrocalcic palexeralfs at 80 130 m are also found typic haploxeralfs are frequent over limestones at higher altitudes 260 m or overlying silicic rocks found at 35 65 m according to the 1967 french classification system they are red fersialitic and brown fersialitic soils and some are integrades with cinnamotnic soils marron encroute

quantification of magnetic coercivity components by the analysis of acquisition curves of isothermal remanent magnetisation abstract a new method of analysing isothermal remanent magnetisation irm acquisition curves based on cumulative log gaussian analysis robertson and france phys earth planet inter 82 1994 223 234 is proposed it is based on the curve fitting of the irm acquisition curve versus the logarithm of the applied field with i the acquisition curve on a linear scale ii the acquisition curve expressed as a gradient and iii the acquisition curve on a probability scale even when a sample is not saturated its magnetic properties can be defined although with less certainty the number of magnetic components required for an optimal fit to a measured irm acquisition curve is evaluated statistically the method discriminates on the basis of different mineral coercivity therefore additional rock magnetic tests are still required to separate minerals with similar coercivities

paleopedology of terrae rossae rodoxeralfs from quaternary calcarenites in nw morocco abstract selected terrace rossae or rhodoxeralfs from calcarenites in all probability of mid pleistocene age in the vicinity of rabut show a strong mineral weathering and a considerable to extensive formation of clay minerals especially of kaolinites main sources of pedogenic kaolinites mostly of a disordered structure and poor cristallinity are primary feldpars 2 m and smectites 2 0 2 and

polygenetic soil formation on late glacial loess on the susak island reflects paleo environmental changes in the northern adriatic area abstract a polygenetic soil formed on late glacial loess on the island of susak was investigated by means of high resolution depth approach to give pedosedimentary and palaeoenvironmental reconstructions of the late glacial holocene pedosequence the complete polygenetic profile a 2c1 2c2 3btb 4ck defined as eutric leptic regosol geoabruptic siltic ruptic over argic horizon over loess deposit is a result of the interaction of the sediments loess with environmental conditions from the late glacial throughout the holocene both normal pedogenesis and erosion sedimentation driven pedogenesis influenced its development therefore this profile bears valuable imprints of climate vegetation land surface and land use changes in this part of the adriatic area for the time period covering the past 16 ka the 4ck horizon is a remnant of an a c soil profile whose incipient formation corresponds to a steppe like palaeo vegetation and a semi humid to semi arid palaeo climate the 3btb horizon has blocky structure common clay coatings and infillings that are related to the walls of channel macrovoids increased cia al si and ba sr ratios due to the increase of the al and clay contents highest fet fed mnt and mnd values due to abundant redox concentrations and specific clay mineralogy since the obtained age of the loess deposit 4ck horizon underlying the 3btb horizon is 16 1 1 3 ka can be correlated to the late glacial maximum i e ois 2 we find that the period of the bolling allerod warming might have enabled the formation of the highly weathered 3btb horizon within a luvisol like soil after the period of surface stability a period of forest decay and surface instability took place resulting with the erosion of the luvisol the 3btb horizon was then covered with a homogeneous loess material whose deposition can presumably be related to the younger dryas period inside of which the horizons 2c1 and 2c2 are recognized both these horizons are negligibly affected by pedogenesis and contain artefacts the incipient soil formation in the upper part of the profile along with the irregular lower boundary of the a horizon and the lithic discontinuity between the a horizon and the 2c1 horizon points to the possibility of a very recent and minor aeolian deposition however one should not overlook the potential impacts of human activities and or colluvial depositions on the properties of the a 2c1 and 2c2 horizons

abrupt chemical weathering increase across the permian triassic boundary previous studies have suggested a variety of causes for the end permian extinction event including a bolide impact flood basalt volcanism methane clathrate dissociation or some combination of catastrophic processes one common feature of these hypotheses is the prediction of an enhanced earliest triassic greenhouse new high resolution geochemical results from graphite peak antarctica support an abrupt increase in chemical weathering in the earliest triassic among otherwise genetically similar paleosols of similar provenance relative to the latest permian paleosols the earliest triassic paleosol exhibits greater leaching greater accumulation of immobile rees and evidence of lower soil po2 with no evidence of an erosional unconformity between the paleosols which are separated by 15 cm stratigraphically these results support a rapid shift perhaps 10 000 years to an earliest triassic greenhouse and a role for methane release in the extinction event and its aftermath

diagenetic magnetic enhancement of sapropels from the eastern mediterranean sea diagenetic dissolution of magnetic minerals has been widely observed in organic rich sediments from many environments organic rich sediments from the eastern mediterranean sea sapropels recovered during leg 160 of the ocean drilling program reveal a surprising catalogue of magnetic properties sapropels from all sites studied across the eastern mediterranean sea are strongly magnetic and the magnetization is directly proportional to the organic carbon content the magnetization of the sapropels is dominated by a low coercivity probably single domain magnetic mineral with an inverse magnetic fabric that exhibits a clear decay in magnetic properties when exposed to air during heating the magnetic particles irreversibly break down between 360 and 400 c the contrast between the magnetic properties of sapropels and surrounding sediments is marked with remanence intensities of sapropels often being more than three orders of magnitude higher than those of underlying sediments the contrast between the magnetic properties of sapropels and the surrounding sediments is apparently controlled by non steady state diagenesis sulphate reducing conditions dominated during sapropel deposition while overlying sediments were deposited under oxic conditions the mineral responsible for the magnetic properties of sapropels is most likely to have formed under sulphate reducing conditions that existed during times of sapropel formation attempts to identify this mineral have been unsuccessful but several lines of evidence point toward an unknown ferrimagnetic iron sulphide phase the influence of diagenesis on the magnetic properties of cyclically deposited eastern mediterranean sedimentary sequences suggests that magnetic parameters may be a useful proxy for diagenesis in these sediments

the last glacial aeolian record of the island of susak croatia as seen from a high resolution grain size and rock magnetic analysis abstract the loess palaeosol record on the island of susak in croatia is a unique archive of late glacial climate changes in the adriatic region possibly even in the wider area on susak up to 90 m of thick quaternary sediments were deposited and are accessible for detailed palaeoclimate reconstructions in this paper the results of a high resolution grain size and rock magnetic investigation on the last glacial upper pleniglacial sand pit section from susak are presented in spite of its significant thickness the sand pit section does not represent a continuous record it is a result of a very dynamic environment there the deposition of dust and formation of loess has been interrupted by pedogenesis periods of increased sand accumulation erosion due to slope wash and water activity redeposition and wildfires and all in the time period of about 10 000 years of the upper pleniglacial as seen from the irsl dating results the grain size data clearly show a shift towards coarser grain sizes which differs from typical loess regions such predominance of the coarser grained over the fine grained fraction very likely resulted from the predominance of deposition over pedogenesis increased wind activity and proximal source of material the rock magnetic signal preserved in the sediment also differs compared to loess palaeosol records from other regions the susceptibility values are several times higher than in the records from the pannonian basin and from typical eurasian loess both the increased susceptibility values and the grain size are very likely the result of a significant proximal material input from the po river plain

red mediterranean soils in some karstic regions of taurus mountains turkey abstract red soils are found along fractures and between bedding surfaces in karstic regions of both mediterranean and aegean regions of turkey these soils are very unique and information on pedogenesis in karstic regions are rather limited detailed field works were carried out at 17 locations soil profiles were examined at 14 sites and 7 of these were reported here soil samples from thea and b horizons of these soils are used to detailed characterization analyses in the laboratory occurrence of normal soil profiles were unusual in the study regions the fractured structure of limestone leads to unusual water and air circulation when water penetrates into rock fissures and holes and diffuses into sedimentary layers in situ weathering processes take place rock fissures and holes may also be filled in by the transport of soil materials from higher elevations sedimentary petrology and mineralogy of limestones are the factors that control the course of the pedogenesis oxidation of fe especially sulfides pyrite accelerates the soil formation in limestones soils are not present on massive an fractured or fissured limestones and thin and stony red soils are common only at the bottom parts of v shaped dolines however soils are thick and common within the materials that have alternating marl and sandy silty layers vertical movement of soil particles towards the deeper parts of te limestone tkes place as a result of the widening of the lapies which are mostly formed along the fractures most of the red soils in the studied karstic regions were likely developed during the tertiary and ot and humid periods of the quaternary epochs large body of soils which are found in deep limestones suggest their formation under paleochimatic environments

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

climate vs parent material which is the key of stagnosol diversity in croatia abstract stagnosols are the most widespread soils in the pannonian region of croatia in croatia they are referred to as pseudogleys and considered to form primarily by normal top down pedogenesis however the formation of their non calcareous loess parent materials probably involved different sources transports and depositional environments we aimed to determine the courses of soil formation and the characteristics of three stagnosol profiles studied along the mean annual precipitation map gradient 700 1100 mm in the pannonian region of croatia we found that soil redoximorphic features formed in situ by ongoing pseudogleization vertical trends for the clay silt and coarse fine silt ratios pointed to top down pedogenesis however high organic c content at the bottom of one soil profile is the result of erosion sedimentation processes whereas high clay content in the subsoil of another profile was largely the result of sedimentation in a shallow paleo lake therefore some croatian stagnosols should be considered polygenetic each soil profile was classified using the wrb system and the new wrb 2014 version proved more suitable than the previous one wrb 2006 however suggestions for improvements are given in line with the map gradient were several morphological and only two chemical ph and base saturation soil characteristics organic c content did not correspond to map due to variability of forest topsoils clay content and cec did not agree with map due to variability of loess parent materials across the pannonian region of croatia the existence of more than one source of loess material confirmed by the modal analysis and the differences in depositional paleo environments resulted in slightly different mechanical compositions of the investigated parent materials we concluded that both climate and parent material must be regarded as key factors for the formation and characteristics of stagnosols in the pannonian region of croatia and the wider southwestern pannonian basin

luminescence dating and palaeomagnetic age constraint of a last glacial loess palaeosol sequence from istria croatia abstract loess and loess like deposits with intercalated palaeosols are widely distributed in croatia particularly in the pannonian basin in the east and along the adriatic coast in the west which have provided invaluable evidences of quaternary climate change the timing provenance and spatial distribution of such loess deposits have long been a major research interest in the current study a 8 m thick loess palaeosol sequence located near the town of savudrija savudrija section on the northern most cape of the istrian peninsula on the adriatic coast is investigated multiple approaches of luminescence dating and palaeomagnetic age constraint are conducted to understand the timing of the regional aeolian activities and its implications for climate change seven samples were collected from the loess layers of the savudrija section for comprehensive quartz optically stimulated luminescence osl and feldspar post ir infrared stimulation luminescence irsl dating the palaeomagnetic investigation was conducted on 82 oriented samples collected from the upper 6 7 m of the section the quartz osl ages of the upper four samples and the fading corrected pirir225 ages of the lower three samples were used to reconstruct the age framework of the section the results demonstrate that the savudrija loess palaeosol sequence were formed between 70 ka and 9 ka correlated to the time span from the last glacial to early holocene the variation of the magnetic susceptibility of the savudrija section is strictly following the pattern that the palaeosol horizons generate high susceptibility values while the loess horizons show low susceptibility values the palaeomagnetic age constraint is obtained by correlating the magnetic susceptibility record of the savudrija section with other records which gives the age range between 65 ka and 20 ka for the loess palaeosol sequence excluding the lowermost red soil it broadly agrees with the luminescence chronology but conflicts in details demonstrating that the correlation between the different magnetic susceptibility records is questionable furthermore the magnetic susceptibility record suggests that the age of 70 ka of the red soil at the bottom of the section might be still ambiguous and needs further study

iron oxide mineralogy of terra rossa and its genetic implications abstract fe d fe d fe t hematite geothite ratios and al substitution in hematite and goethite were found to vary to a rather limited extent in 48 terra rossa samples from various locations around the world this seems to indicate a rather specific pedoenvironment in which terra rossa is formed it is suggested that this pedoenvironment is characterized by an association of mediterranean climate high internal drainage due to the karstic nature of a hard limestone and neutral ph conditions under those conditions relatively high amounts of fe are released fe d fe t ca 0 7 from autochthonous and or allochthonous primary fe sources followed by preferential formation of hematite over goethite both having a medium level of al substitution the close association between terra rossa and the underlying limestone must therefore be seen in the role the rock plays for the water and air regimes of the soil rather than in its material characteristics except for soil ph neither an fe content in the limestone insufficient to explain the fe content of the solum nor the addition of eolian or alluvial material can therefore be used as an argument against a genetic relationship between terra rossa and its underlying limestone

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

orogenic evolution of the external dinarides in the ne adriatic region a model constrained by tectonostratigraphy of upper cretaceous to paleogene carbonates abstract mesozoic to cenozoic evolution of the central part of the adriatic plate external dinarides and adriatic foreland is still a matter of debate this is expressed by opposing paleogeographic models single carbonate platform adriatic or adriatic dinaridic versus two carbonate platforms adriatic and dinaridic separated by the inter platform budva cukali basin estimates of shortening during adria ne subduction that resulted in the development of the dinaric alps differ substantially the single platform model involves minor shortening achieved by folding and faulting along steep reverse faults the two platform model involves significant shortening achieved mainly by thrust stacking which resulted in almost complete underthrusting of the intervening basinal deposits analysis of upper cretaceous to paleogene stratigraphical data from both outcrops and boreholes allows regional correlation and the interpretation of major lithostratigraphic units as a result a few tectonostratigraphic units are recognized the tectonostratigraphy is used as a basis for a new model on the late mesozoic to cenozoic evolution of the region generally adriatic and dinaridic segments acted as major regional crustal entities of adria the upper portions of the sedimentary cover were differentially affected by progressive southwestward verging thin skinned deformations during the paleocene to eocene miocene the adriatic foreland stayed out of the deformations and is characterized predominantly by wrench and salt tectonics the regional tectonic map shows arcuate thrust fronts of the external dinarides they could be a consequence of both differential propagation of early orogenic thin skinned deformations over crustal fragments separated by transversal faults and or differential isostatic movements of the fragments the collision zone of the adriatic and dinaridic segments is characterized by late orogenic oligocene to miocene thick skinned compressional uplift exhumation related gravity gliding and still active escape tectonics wrenching these processes masked primary thin skinned deformations a significant amount of shortening within and between the thin skinned sedimentary covers is proposed therefore the question of the general paleogeography of the region and the original nw extent of the budva cukali basin ne adriatic trough remains open

stratigraphy and palaeoenvironmental significance of the loess deposits on susak island dalmatian archipelago abstract the loess of susak island is the most impressive aeolian deposit in the dalmatian archipelago as it reaches about twenty metres in thickness the base of the sedimentary sequence consists of a shore platform which in the southern part of the island is covered by late middle pleistocene fossil dunes elsewhere the shore platform has been affected by gelifraction and is covered by slope waste deposits above these a thick sequence of aeolian deposits occurs composed in the lower part of cross laminated sandy loam and thick loess cover interstratified with a level reworked by running water and slightly developed chernozems the upper part of the sequence has been strongly affected by anthropogenic reworking in historical times the loess is composed of unweathered subrounded quartz feldspar mica and limestone granules the heavy mineral association is mainly from metamorphic paragenesis and has the same composition as the sediments of the po plain the aeolian sediments are rather homogeneous and composed mainly of coarse silt they are coarser in comparison with those of losinj island 12 km northeast of susak which are typical silty loess indicating a wind direction from southwest to northeast on the basis of the pedostratigraphic data loess sedimentation is referred to the first pleniglacial period of the upper pleistocene the loess of susak island originated in a dry environment by wind deflation of the po river sediments the quick progradation of alluvial and deltaic deposits towards the east southeast due to the sea level drop provided large barren areas exposed to wind erosion

mineralogical and geochemical indicators of the polygenetic nature of terra rossa in istria croatia abstract terra rossa in istria is situated on the jurassic cretaceous paleogene carbonate plain and is considered a polygenetic reddish soil which bears typical terra rossa fe oxide characteristics e g fe d and fe d fe t the difference in particle size mineralogy and geochemistry observed between terra rossa and the insoluble residue of limestones and dolomites clearly indicates that the additions of external materials might have diminished the influence of insoluble residue of limestones and dolomites as the primary parent material of terra rossa in istria terra rossa is clay and silty clay composed of quartz plagioclase k feldspar micaceous clay minerals illitic material and mica kaolinites kl d and kl chlorite vermiculite low charge vermiculite or high charge smectite mixed layer clay minerals other than illitic material hematite goethite and xrd amorphous inorganic compound calcite dolomite and boehmite are sporadically present and are of local importance kaolinites and illitic material are dominant clay mineral phases in the clay fraction of all terra rossa from istria kaolinite which does not form intercalation compounds with dimethylsulfoxide dmso is the dominant mineral phase in fine clay and is considered predominantly authigenic rather then inherited from parent materials neither the content and particle size distribution nor the bulk and clay mineralogy of the insoluble residue of limestone and dolomite support development of terra rossa entirely by dissolution of carbonate rock if terra rossa has developed only from the insoluble residue of limestone and dolomite its clay content due to weathering should be higher than that in the insoluble residues which is not the case plagioclase was found only in one insoluble residue while all terra rossa samples contain this mineral moreover insoluble residues do not contain vermiculite which was observed in small amounts in clay fraction of all terra rossa samples na 2 o k 2 o 100 zr nb and zr ti 1000 ratios in the majority of terra rossa samples are much higher than in the insoluble residue of limestones and dolomites which also supports external material influence in the genesis of terra rossa materials other than the insoluble residue of limestones and dolomites which might have contributed to terra rossa are loess sediments whose deposition was very important recurrent process in istria probably since the early middle pleistocene and flysch sediments which extended much more southwards from its present position analyses performed indicate that both loess older than that of the upper pleistocene age and flysch might have contributed in the genesis of terra rossa

terra rossa genesis implications for karst and eolian dust a geodynamic thread abstract although terra rossa has long been thought to form by residual dissolution of limestone and or by accumulation of detrital mud ash or dust on preexisting karst limestones we present conclusive new field and petrographic evidence that terra rossa forms by replacement of limestone by authigenic clay at a moving metasomatic front several centimeters wide the red clay s major chemical elements al fe and si probably come from dissolved eolian dust the replacement of calcite by clay exhibits a serrated microstylolitic texture that helps prove that replacement happens not by dissolution precipitation as conventional wisdom has it but by pressure solution of calcite driven by the crystallization stress generated by the growth of clay crystals the acid produced by the isovolumetric replacement of limestone by clay quickly dissolves out additional porosity permeability in an adjacent slice of limestone within the front triggering a reactive infiltration instability that should theoretically

magnetic stratigraphy of chinese loess as a record of natural fires magnetic susceptibility records of paleosols and loess show high correlation with oxygen isotope stratigraphy of ocean sediments kukla 1987 providing a global paleoclimatic record different models have been put forth to explain the nature and cause of susceptibility variations but consensus has not yet been achieved our low temperature studies reveal a secondary magnetite component in paleosols that is characterized by a higher verwey transition 115k than that for the magnetite 100 k in unaltered loess the same shift in the verwey transition can be achieved by heating and cooling loess samples this is consistent with a new hypothesis that the magnetic signal from paleosols may be produced by natural fires in the past natural fire intensity is sensitive to the amount of annual precipitation so that increased fire induced susceptibilities should reflect an increase in the humidity of regional climate

soil development along an elevational transect in the western sierra nevada california soil development along an elevational transect on the western slopes of the the central sierra nevada was investigated to assess the effects of climate on soil properties and processes the transect of seven soils formed in granitic residuum spans elevations from 198 to 2865 m with mean annual temperature and precipitation differences of 13 c 3 9 16 7 and 94 cm 33 127 respectively soil ph decreased by about two units and base saturation decreased from 90 to 10 with increasing elevation concentrations of organic c in the solum increased with elevation with the largest single increase occurring between the oak woodland 5 6 kg c m2 and mixed conifer sites 10 15 kg c m2 clay mineralogy showed a general trend of desilication and hydroxy al interlayering of 2 1 layer silicates with increasing elevation the degree of chemical weathering based on clay and secondary fe oxide concentration in the solum showed a maximum clay 536 kg m2 and fe oxides 24 kg m2 at mid elevations having intermediate levels of precipitation and temperature while some soil properties show a continuous progression e g organic carbon base saturation clay mineralogy with elevation other properties e g ph soil color clay and secondary fe oxide concentrations show a pronounced change threshold type step over a short distance at about 1600 m the explanation for the abrupt nature of this shift is not known however it coincides with the approximate elevation of the present day average effective winter snow line

theory and application of the day plot mrs ms versus hcr hc 2 application to data for rocks sediments and soils 1 new theoretical curves relating the hysteresis parameters mrs ms and hcr hc for single domain sd superparamagnetic sp pseudo single domain psd and multidomain md grains and their mixtures are applied to published data for natural materials the day plot of mrs ms versus hcr hc has been used to crudely classify samples into box like sd psd and md or sometimes incorrectly md sp regions with arbitrary boundaries new type curves for md psd sd md and sd sp grains and mixtures permit more subtle and precise modeling the predicted md trend and its junction with the psd trend are observed in two data sets for magnetite spherules from carbonate rocks and for temperature varying hysteresis results spanning the verwey transition the latter data are the basis of a suggested new method for pinpointing the psd md threshold size selected data for pottery clays soils and paleosols generally follow sd md type curves and indicate intermediate size psd magnetite with narrow to broad size distributions a lake sediment section with known grain size progression tracks in the predicted sense along the sd md trend selected data for glaciomarine and pelagic sediments are also generally compatible with sd md trends examples of remagnetized carbonate rocks submarine basaltic glasses and glassy rims of pillow basalts all follow predicted sp sd or sp psd mixing curves with a large range in volume fraction of sp grains 0 75 but a narrow range of sp particle sizes 10 2 nm larger sp grains spanning the range to sd size 25 30 nm are absent for unknown reasons oceanic dolerites gabbros and serpentinized peridotites in some cases fall in a novel region of the day plot parallel to but below magnetite sd md mixing curves

mineralogical and geochemical characteristics of quaternary sediments from the island of susak northern adriatic croatia middle and upper pleistocene loess palaeosol sequences up to 90 m thick are exposed on the island of susak located in the northern adriatic sea in croatia during glacial times the sea level was up to about 120 m lower and a significant part of the adriatic became land the source area of the primary aeolian sediments was in the vicinity of the island and is related to the southward extended river po plain the loess has a mainly clayey to sandy silt or sand grain size and is intercalated by at least three tephras numerous palaeosols and calcareous segregations the heavy mineral association points to metamorphic and igneous rocks from alpine regions as source material of the loess geochemical and mineralogical properties of loess and palaeosols differentiate one from another and reflect the intensity of weathering and pedogenesis the oldest tephra contains vitroclasts and serrated clinopyroxene while the middle and the youngest tephra along with vitroclasts contain idiomorphic augite as diagnostic volcanic features based on bulk rock and vitroclast chemistry morphology of pyroxenes and the age of the loess sandwiching the tephra the potential source of this volcanic material could very likely be the campanian or aeolian volcanic province in southern italy infrared stimulated luminescence dating results show that the major part of the aeolian deposits including the tephra layers correlates to mis 3 mis 5

preservation of oxygen isotope compositions in granulites from northwestern canada and enderby land antarctica implications for high temperature isotopic thermometry preservation of high temperature mineral isotopic compositions is necessary for successful high temperature isotopic thermometry other requirements include large fractionations between constituent minerals well calibrated equilibria carefully designed sampling strategies and data handling techniques that quantitatively account for retrograde exchange here we apply isotopic thermometry and data handling techniques to calculate and contrast mineral pair apparent temperature data and observed closure temperature data tc observed cf farquhar et al 1993 for the very high temperature 900 c dry granulites of the taltson magmatic zone of northwestern canada and the napier complex of enderby land antarctica the isotopic compositions of garnet grains from both terrains reflect high temperature conditions 950 c and point to this mineral as an excellent candidate for isotopic thermometry the isotopic compositions of quartz pyroxene ilmenite and magnetite indicate that they equilibrated to lower temperature conditions 900 c due to faster rates of oxygen diffusion in these minerals possibly enhanced by exsolution and ductile deformation compared with garnet our temperature data for garnet and pyroxene are 200 c higher than is possible to explain by existing wet diffusion data but is consistent with dry diffusion data suggesting that the extremely dry nature of these rocks may have played a significant role in the preservation of high temperature isotopic compositions both quartz and magnetite exhibit subgrain features indicative of ductile deformation quartz magnetite temperatures from the napier complex are similar to those inferred for a late d3 deformation and are lower than those predicted by dry diffusion data we infer that the quartz magnetite isotopic fractionations reflect deformation enhanced exchange that accompanied d3 garnet in these same samples did not undergo ductile deformation and did not exchange oxygen with coexisiting phases during cooling this may reflect strain partitioning between less easily deformed low abundance garnet and more easily deformed matrix quartz and magnetite the resistance of garnet to ductile deformation in these rocks is a second reason why garnet is suitable for isotopic thermometry

osl thermochronometry of feldspar from the ktb borehole germany the reconstruction of thermal histories of rocks thermochronometry is a fundamental tool both in earth science and in geological exploration however few methods are currently capable of resolving the low temperature thermal evolution of the upper 2 km of the earth s crust here we introduce a new thermochronometer based on the infrared stimulated luminescence irsl from feldspar and validate the extrapolation of its response to artificial radiation and heat in the laboratory to natural environmental conditions specifically we present a new detailed na feldspar irsl thermochronology from a well documented thermally stable crustal environment at the german continental deep drilling program ktb there the natural luminescence of na feldspar extracted from twelve borehole samples 0 1 2 3 km depth corresponding to 10 70 c can be either i predicted within uncertainties from the current geothermal gradient or ii inverted into a geothermal palaeogradient of 29 2 c km 1 integrating natural thermal conditions over the last 65 ka the demonstrated ability to invert a depth luminescence dataset into a meaningful geothermal palaeogradient opens new venues for reconstructing recent ambient temperatures of the shallow crust 200 c ma 1 range although na feldspar irsl is prone to field saturation in colder or slower environments the method s primary relevance appears to be for borehole and tunnel studies where it may offer remarkably recent 0 3 ma information on the thermal structure and history of hydrothermal fields nuclear waste repositories and hydrocarbon reservoirs

terra rossa genesis by replacement of limestone by kaolinite iii dynamic quantitative model abstractwe model quantitatively the chemical dynamics of terra rossa formation that we deduced earlier from new field and petrographic evidence the key phenomenon is that authigenic kaolinite a proxy for kaolinite solid solutions and other clays replaces limestone at a downward moving reaction front at the base of the existing terra rossa the chemical elements needed to make the authigenic clay are assumed to come from dissolution of eolian clay dust deposited at the surface the model consists of equations of mass conservation in one spatial dimension that incorporate infiltration diffusion and replacement and dissolution reactions distinctive elements of the model are that 1 the kinetics of the kaolinite for calcite replacement is dominated by the crystallization stress generated by the kaolinite growth in accordance with the view that replacement happens not by dissolution precipitation but by guest mineral growth driven pressure solution of the host 2 the field observation that the terr

last glacial loess in the conterminous usa the conterminous united states contains an extensive and generally well studied record of last glacial loess the loess occurs in diverse physiographic provinces and under a wide range of climatic and ecological conditions both glacial and non glacial loess sources are present and many properties of the loess vary systematically with distance from loess sources united states midcontinent last glacial loess is probably the thickest in the world and our calculated mass accumulation rates mars are as high as 17 500 g m 2 yr at the bignell hill locality in nebraska and many near source localities have mars greater than 1500 g m 2 yr these mars are high relative to rates calculated in other loess provinces around the world recent models of last glacial dust sources fail to predict the extent and magnitude of dust flux from the mid continent of the united states a better understanding of linkages between climate ice sheet behaviour routing of glacial meltwater land surface processes beyond the ice margin and vegetation is needed to improve the predictive capabilities of models simulating dust flux from this region r 2003 elsevier ltd all rights reserved

estimating peak currents at ground lightning impacts using remanent magnetization 1 the impact of lightning is permanently recorded in struck material by a secondary magnetization called lightning induced remanent magnetization lirm we introduce an original rock magnetic method based on alternating field demagnetization to define both the geometry and the intensity of the peak lightning magnetic field it also provides positive evidence than a material has effectively been struck on a schoolyard tree struck by lightning we were able to locate the impact to within a few centimeters to prove that it was a vertical negative current and to estimate a peak current intensity of 99 7 ka this value is 14 ka higher than the one provided by meteorage lightning detection network and offers an independent calibration

temperature dependence of magnetic susceptibility in an argon environment implications for pedogenesis of chinese loess palaeosols summary temperature dependence of magnetic susceptibility t has been widely used to determine changes in mineralogy of natural samples during heat treatment we carried out integrated rock magnetic experiments to interpret the t curves of the chinese loess palaeosols in argon we used both raw materials and heated samples in addition we also investigated the magnetic properties of magnetic extracts and residues to quantify contributions from each fraction to the bulk magnetic properties for the heating curves the susceptibility loss 30 per cent between 300 400 c is caused by the inversion from pedogenic fine grained maghemite to haematite suggesting that the susceptibility loss can be used as a new concentration index of the pedogenic fine grained superparamagnetic sp particles in the chinese loess palaeosols unlike the warming curves the cooling curves are dominated by newly formed fine grained magnetites with a dominant size of 35 nm the onset for the new production of these fine grained magnetic particles occurs at 400 c it is interesting that the room temperature magnetic susceptibility ph of the samples heated after a 700 c run is independent of the degree of pedogenesis and saturates at approximately 33 35 10 7 m3 kg 1 indicating that the susceptibility enhancement is controlled only by the reduction of fe bearing aeolian minerals during heating it appears that the 700 c thermal treatment in argon could be in some sense an analogue to the pedogenic processes thus we predict that 33 35 10 7 m3 kg 1 is the maximum susceptibility that pedogenesis can generate for the last interglacial palaeosol unit s1 in practice ph would be useful to quantify the aeolian inputs to the chinese loess plateau

tectonic constraints on the late pleistocene holocene relative sea level change along the north eastern adriatic coast croatia abstract in spite of very favourable coastal features late pleistocene holocene relative sea level changes along the eastern adriatic coast are still not completely resolved mostly due to the intensive and complicated regional and local neotectonics we gathered current knowledge that generally presents the north adriatic area as subsiding one and proposed a reconstruction in new light of possible very slow local uplift average rate of 0 1 0 25 mm a for last 80 ka which is supported by well dated submerged speleothems and tectonic reconstruction in addition such a scenario supports also the formation of tidal notches that are common in the north adriatic region but not yet entirely understood however according to the latest mediterranean data on sea level during the marine isotope stage mis 5 1 being at 1 m 80 ka ago we do not dismiss the possibility of subsidence which would have been 0 18 0 23 mm a on average for the last 80 ka but notch formation under such condition would not have been realistic apparently the position of the north eastern adriatic coast on a convergence area requires extensive palaeoenvironmental studies including structural lithostratigraphical palaeontological archaeological and radiometric data and application of isostatic modelling

evolution of the adriatic carbonate platform palaeogeography main events and depositional dynamics abstract the adriatic carbonate platform adcp is one of the largest mesozoic carbonate platforms of the perimediterranean region its deposits comprise a major part of the entire carbonate succession of the croatian karst external or outer dinarides which is very thick in places more than 8000 m and ranges in age from the middle permian or even upper carboniferous to the eocene however only deposits ranging from the top of the lower jurassic toarcian to the top of the cretaceous can be attributed to the adcp defined as an isolated palaeogeographical entity although the entire carbonate succession of the karst dinarides was deposited within carbonate platform environments there were different types of carbonate platforms located in different palaeogeographical settings carboniferous to middle triassic mixed siliciclastic carbonate deposits were accumulated along the gondwanian margin on a spacious epeiric carbonate platform after tectonic activity culminating by regional middle triassic volcanism recorded throughout adria the african promontory a huge isolated carbonate southern tethyan megaplatform abbreviated as stm was formed with the area of the future adcp located in its inner part tectonic disintegration of the megaplatform during the middle to late early jurassic resulted in the establishment of several carbonate platforms including the adriatic apenninic and apulian separated by newly drowned deeper marine areas including the adriatic basin as a connection between the ionian and belluno basins lagonero basin and the area of the slovenian and bosnian troughs the adcp was characterised by predominantly shallow marine deposition although short or long periods of emergence were numerous as a consequence of the interaction of synsedimentary tectonics and eustatic changes also several events of temporary platform drowning were recorded especially in the late cretaceous when synsedimentary tectonics became stronger leading up to the final disintegration of the adcp the thickness of deposits formed during the 125 my of the adcp s existence is variable between 3500 and 5000 m the end of adcp deposition was marked by regional emergence between the cretaceous and the palaeogene deposition during the palaeogene was mainly controlled by intense synsedimentary tectonic deformation of the former platform area some carbonates mostly eocene in age were deposited on irregular ramp type carbonate platforms surrounding newly formed flysch basins and the final uplift of the dinarides reached its maximum in the oligocene miocene the adriatic carbonate platform represents a part although a relatively large and well preserved one of the broader shallow water carbonate platform that extended from ne italy to turkey although its continuity is somewhat debatable in the area near albanian greece boundary this large carbonate body which was deformed mostly in the cenozoic including a significant reduction of its width needs a specific name and the central mediterranean carbonate platform is proposed abbreviated to cmcp although the local names such as adcp for its nw part should be kept to enable easier communication and to facilitate description of local differences in platform evolution

late pleistocene loess palaeosol sequences in the vojvodina region north serbia late pleistocene loess palaeosol sequences are widespread in the vojvodina region with thicknesses reaching a maximum of about 20 m our investigations include more than 40 of these loess sections geochronology of the last glacial loess palaeosol sequences based on lumines cence dating and amino acid racemisation provides correlations between upper pleistocene loess palaeosol sediments in vojvodina and comparable deposits at other european localities sedimentary logs of magnetic susceptibility grain size measurements and carbonate content combined with malacological evidence indicate two main relatively cold and arid phases during the last glacial period related to intensive accumulation of loess units l1l1 and l1l2 as well as many brief episodes of dry and windy climatic conditions suggesting a possible relationship with cold events recorded in the north atlantic region generally late pleistocene climate in the region was dry and relatively warm compared with glacial period sites in central europe and was characterised by sharp differences between glacial and interglacial modes new data and interpretations presented in this study emphasise the significance of loess palaeosol sequences in vojvodina for the reconstruction of the temporal and spatial evolution of late pleistocene palaeoclimate in this part of europe copyright 2007 john wiley sons ltd

speleothem based quaternary research in croatian karst a review abstract speleothems as secondary carbonate deposits precipitate in the cave environment from the water originally sourced from the ocean transferred via atmosphere through soil and epikarst into the cave system as such they archive valuable information on the ongoing changes in the atmosphere biosphere hydrosphere and lithosphere which may be used for palaeoenvironmental reconstructions especially for the quaternary period speleothem based quaternary research in croatia started in the 1960 s with the utilization of the flowstone and speleothems whose radiometric ages 14c and u th provided constrained chronological framework for underlying fossils or archaeological material mainly without any further palaeoenvironmental interpretations since the 1990 s several studies have used speleothems for the reconstruction of particular phases of speleogenesis while in the early 2000 s investigation on submerged speleothems started with the aim to reconstruct quaternary relative sea level changes along the eastern adriatic coast only after that thorough research on subaerial speleothems from the different regions of the croatian karst has been initiated usually associated with monitoring programs this paper gathers the most important speleothem based studies displaying potential of this still understudied but promising area in the terms of palaeoclimate and palaeoenvironmental changes in a wider european and global context

luminescence dating of upper pleistocene loess from the island of susak in croatia abstract the loess paleosol sequence on the island of susak is a detailed late pleistocene archive of climate change in the north adriatic sea of croatia quaternary deposits on susak are up to 90 m thick and consist of loess loess derivatives and sand intercalated by numerous paleosols and at least three tephra layers infrared stimulated luminescence irsl dating was carried out on polymineral fine grained material thirteen samples were collected from two sections on susak to study the timing of loess accumulation and soil formation the single aliquot regenerative sar protocol as well as the multiple aliquot additive dose maad protocol were applied for equivalent dose d e determination the irsl ages were fading corrected independent age control is provided by radiocarbon dating of charcoal remains the results show that loess and loess derivatives from the investigated sections represent a very detailed record correlating to the marine isotope stage mis 3 with short periods of stronger sand deposition and occasional volcanic activity the extraordinary thickness of the deposits is very likely related to the vicinity of the river po plain which extended to the southeast due to marine regressions of the adriatic sea during the cold periods of the pleistocene