the geochemical fingerprints of different tectonomagmatic environments using hygromagmatophile element abundances of tholeiitic basalts and basaltic andesites abstract using hygromagmatophile element abundances normalized to primordial mantle composition it is possible to discriminate between the tectonic settings of tholeiitic basalts and basaltic andesites 47 0 53 5 sio2 based on field and chemical evidence data from provinces or grouped localities have been compiled in order to establish chemical reference data sets for ocean island continental ocean ridge and floor subduction zone and back arc environments the disturbing effects of crustal contamination and hydrothermal alteration on the hygromagmatophile h element patterns are of minor significance in the recognition of plate tectonic settings on the basis of the data sets magmas from a number of ambiguous tectonic settings have been recognized using their h element patterns attention is directed to problems concerning rifting and drifting related basalts in an apparent continental setting and to the origin of ophiolite complexes using available data the pillow lavas of the troodos ophiolite complex cyprus are recognized as basalts erupted in a subduction zone environment

late precambrian crustal accretion rates in northeast africa and arabia apparent late precambrian growth rates for continental crust in the arabian nubian craton are implausibly high for simple arcaccretion models if correct these rates imply that some special non uniformitarian process occurred to rapidly produce continental crust assuming that the dominant mechanism for continental growth is by arc magmatism roughly 100 of global island arc production at current rates would have had to accrete in this region from 900 to 600 ma one solution to this paradox is that large amounts of preexisting sialic basement have so far gone undetected and should not be included in the estimate for crustal growth during late precambrian time published radiometric data indicate that older continental material makes up the eastern and western margins of the exposed shield we interpret these and other data to suggest that the larger part of the arabian nubian craton including the platform obscured by phanerozoic cover east and west of the exposed shield is older continental crust in this case a growth rate approximately 20 of the modern global rate is required and nonuniformitarian crustal growth is not necessary to explain late precambrian accretion of the arabian nubian craton

the karoo igneous province a problem area for inferring tectonic setting from basalt geochemistry tholeiitic basalts and associated intrusives are the major component of the karoo igneous province they are of mesozoic age and constitute one of the world s classic continental flood basalt cfb provinces it has been argued that most karoo basalts have not undergone significant contamination with continental crust and that their lithospheric mantle source areas were enriched in incompatible minor and trace elements during the proterozoic the only exceptions to this are late stage morb like dolerites near the present day continental margins which are considered to be of asthenospheric origin when data for the southern karoo basalts are plotted on many of the geochemical discriminant diagrams which have been used to infer tectonic setting essentially all of them would be classified as calc alkali basalts cab s or low k tholeiites virtually none of them plot in the compositional fields designated as characteristic of within plate basalts there is little likelihood that the compositions of the karoo basalts can be controlled by active subduction at the time of their eruption and no convincing evidence that a subduction component has been added to the subcontinental lithospheric mantle under the entire area in which the basalts crop out it must be concluded that the mantle source areas for cab s and the southern karoo basalts have marked similarities in contrast the data for northern karoo basalts largely plot in the within plate field on geochemical discriminant diagrams available data suggest that the source composition and or the restite mineralogy and degree of partial melting are different for southern and northern karoo basalts there is no evidence for any difference in tectonic setting between the southern and northern karoo basalts at the time they were erupted this appears to be clear evidence that specific mantle source characteristics and or magmatic processes can vary within a single cfb province to an extent that renders at least some geochemical discriminant diagrams most unreliable for classifying tectonic environment with respect to continental volcanic rocks

two thousand years of archeointensity from west africa this study presents 17 archeointensity estimates from senegal and mali two neighboring countries in west africa for the period 1000 bce to 1000 ce the archeological artifacts used in this study were collected during the course of two separate projects together spanning 22 years and across 8 separate excavations a primary objective of this study was to get accurate dates hence only samples with independent age constraints from pottery style detailed stratigraphy and 14c dates were used a total of 236 specimens from 63 samples were subjected to a double heating paleointensity experiment izzi method from which 95 specimens were selected using a set of very strict selection criteria the paleointensity results were corrected for differential cooling rate effects and remanence anisotropy additionally we demonstrate the equivalence of using tensors derived from anhysteretic and thermal remanences for correcting remanent anisotropy of the specimens and use the former for the anisotropy correction our data show good agreement with the most recent paleosecular variation model but are lower than the pre existing data which are mostly from egypt and morocco the presence of substantial non axial dipolar contributions in the region is evident when virtual axial dipole moments vadms from the published literature are calculated for 20 latitudinal bands and compared with our data the average vadm values show a distinct latitudinal gradient a prominent feature of this dataset is an intensity high observed prior to 700 ce in both senegal and mali comparing this peak with existing records from regions further to the north suggests a small but significant temporal offset and is interpreted to be additional evidence for a geomagnetic field with a significant and rapidly changing non axial dipolar contribution

paleointensity of the geomagnetic field from dated lavas of the chaine des puys france 1 7 12 thousand years before present paleointensities were determined by the thellier method for six dated lava flows from the chaine des puys france with ages from 7 to 12 ka ka kiloannum before present the three younger flows overlap the archaeomagnetic period for europe and the older flows extend the record to more ancient times our results support the quasi sinusoidal variation of the geomagnetic field intensity since 10 ka for europe punctuated by a peak virtual dipole moment of about 11 1022 a m2 between 8 and 10 ka the data from 10 to 12 ka show considerably lower virtual dipole moments between 4 and 5 1022 a m2 about 60 of the global average since 10 ka when compared with available worldwide data the maximum in the virtual dipole moment between 8 and 10 ka is supported by measurements from japan and possibly hawaii lower than average virtual dipole moments between 10 and 12 ka have also been observed in north america and hawaii the existing data suggest that from 8 to 10 ka the geomagnetic field supported a dipole moment up to 30 above and from 10 to 12 ka about 30 below the average value since 10 ka

paleointensity determination using continuous thermal measurements by a high temperature vibrating thermomagnetometer a vibrating thermomagnetometer which measures magnetization m continuously at high temperature is used to test a new method of paleointensity determination involving single rather than double heatings loss of natural remanent magnetization nrm is recorded by the average of 20 25 measurements at the peak temperature t achieved in a zero field heating step partial thermoremanent magnetization ptrm is calculated from the average m after in field cooling to room temperature t0 for comparison with data taken at t0 values of m measured at t are multiplied by ms t0 ms t with the aid of the thermomagnetic or ms t curve measured on a chip of the sample nrm versus ptrm results from 11 heating cooling steps on a diabase containing both single domain magnetite inclusions in plagioclase and coarser multidomain magnetite grains reproduce the features of thellier double heating paleointensity results for samples from the same site the nrm ptrm plot is nonlinear with convex down curvature for a stringent validation of the single heating method a truly single domain sample needs to be tested

secular variation of the earth s magnetic field in the balkan region during the last eight millennia based on archaeomagnetic data summary the first archaeomagnetic secular variation sv curves for the whole southern balkan peninsula are presented these are based on all data within a 700 km circle centred at thessaloniki 40 60on 23 00oe this data set consists of 325 directional and 625 intensity data mainly from greece bulgaria serbia and southern hungary some data from southern italy are also included the sliding moving window technique was used to calculate a continuous sv curve for intensity while the directional sv curves were calculated using the bivariate extension of the fisher statistics these curves are well constrained and clearly show the main features of the geomagnetic field variation in this region during the last eight millennia comparisons with the predictions of the scha dif 3k and scha dif 8k regional and the cals7k 2 and arch3k 1 global geomagnetic field models show a good agreement for the last 3000 years but differences for older times the balkan sv curves identify several rapid changes of the geomagnetic field in eastern europe and can be used as reference curves for archaeomagnetic dating in the balkan peninsula

age of feiran basement rocks sinai implications for late precambrian crustal evolution in the northern arabian nubian shield basement exposed on the perimeter of the red sea was created during the pan african event at the end of the precambrian pre pan african crust in the northern part of this region has not yet been identified this paper reports the results of rb sr whole rock and u pb zircon dating of gneisses and related basement units from the wadi feiran area in the sinai peninsula where the existence of such older basement has previously been suggested a post tectonic extensional dyke gives a rb sr age of 591 9 ma with an initial 87 sr 86 sr ratio of 0 7034 0 0002 rb sr whole rock and thin slab dating of paragneisses gives ages of c 610 ma with an initial 87 sr 86 sr ratio of 0 7035 a u pb zircon age of 632 3 ma is interpreted as either the time of formation of these gneisses or the age of the crust sampled by protolith sediments granodiorite to the east gives a u pb zircon age of 782 7 ma and is interpreted as representing the westernmost extent of a 780 50 ma terrane that extends across sinai into jordan uplift and erosion of the 780 50 ma terrane supplied detritus to flanking terranes in n and se sinai this region thus acted as a foreland to the younger accretionary and extensional units to the south and west that were active later in the pan african event there is still no evidence for pre pan african basement in the precambrian units around the northern red sea east of the nile

archaeological significance of the palaeolithic charcoal assemblage from krems wachtberg abstract at the palaeolithic site of krems wachtberg numerous charcoal remains were excavated since 2005 they were concentrated in the living floor layer 4 4 especially in fireplaces 1 and 2 and several pits but also mixed into sediments above the living floor since 2008 vias dendrolab vienna institute for archaeological science university of vienna has been cooperating with the excavators to investigate these charcoal samples for wood species analysis dendrochronological synchronization and also to evaluate their palaeoclimatic potential the dominant wood type is pine which includes the species pinus sylvestris pinus mugo and pinus cembra sibirica two other gymnospermous wood types were found among the samples several charcoal pieces belong to picea abies larix decidua which cannot be separated by means of wood anatomy and a single specimen of abies sp was found a single angiosperm wood remain was analysed as fagus sylvatica dendrochronological investigations singled out a number of samples with very similar ring patterns which obviously had been growing at the same time as these clusters do not match each other samples were either not contemporary or grew on climatologically differing places as a result of these studies we were able to ascertain the synchronous use of fireplaces 1 and 2 in at least one phase the advanced methods of charcoal analysis described in this paper can be used for detecting and synchronizing settlement phases on many archaeological sites in particular it is possible to significantly enhance the temporal resolution achievable with 14c ages on wood charcoal

a new three axis vibrating sample magnetometer for continuous high temperature magnetization measurements applications to paleo and archeo intensity determinations we have developed a new three axis vibrating sample magnetometer which allows continuous high temperature magnetization measurements of individual cylindrical 0 75 cm3 samples up to 650 c and the acquisition of thermoremanent magnetization trm in any direction and field intensity up to 200 t we propose a fast less than 2 5 h automated experimental procedure adapted from boyd s nature 319 1986 208 209 modified version of the thellier and thellier ann geophys 15 1959 285 376 method which provides continuous intensity determinations over a large typically 300 c temperature interval for each sample this procedure allows one to take into account both the cooling rate dependence of trm acquisition and anisotropy of trm several examples of analyses of ancient magnetization demonstrate the quality and reliability of the data and illustrate the promising potential of this new instrument in paleo and archeomagnetism

sediment subduction and the source of potassium in orogenic leucitites leucitites from the italian volcanic province show a marked enrichment of the large ion lithophile elements lile over the high field strength elements hfse indicative of a subduction related origin despite sr and nd isotope ratios similar to those in lamproites trace element variations do not suggest the latter as a source for the k enrichment instead potassium and the other lile and rare earth elements ree are derived from subducted sediments in a multicomponent mixing process that involves both dehydration and partial melting of the subducted material the slightly elevated 18 o and high 87 sr 86 sr values of the primitive italian lavas are shown to be consistent with a three component mixing model which can also explain other unusual geochemical features of the italian lavas stabilization of phlogopite in hybridized mantle above the subduction zone is regarded as an essential aspect of the petrogenesis of the orogenic leucitites

krems wachtberg excavations 2005 12 main profiles sampling stratigraphy and site formation abstract since 2005 detailed archaeological investigations have been carried out at the upper palaeolithic site of krems wachtberg in eastern austria where a well preserved gravettian find layer is embedded in an 8 m high late pleistocene loess sequence the excavations are accompanied by interdisciplinary sampling strategies applied on the main profiles entire sediment series as well as on selected locations within the archaeological context the latter include both evident anthropogenic structures an in situ occupation surface with hearths and burials and periglacial features that together determine the morphology and explain the formation of the main gravettian find horizon

historic and paleomagnetic secular variation and the earth s core dynamo process this paper attempts to summarize briefly the recent and ongoing efforts of the geomagnetism and paleomagnetism community to understand both the earth s magnetic field secular variation and its implications for the core dynamo process secular variation is defined in this paper as the general spatio temporal variation of the field secular change will refer to the first time derivative of the spatial field strict geomagnetic definition of secular variation we will emphasize here the long term 10 year or longer behavior of the historic secular variation hsv for this is the variation that is comparable with the paleomagnetic secular variation psv two important related topics the 1969 1970 geomagnetic jerk in secular acceleration and the spatial geomagnetic field components due to crustal or mantle sources are treated more fully in other reviews

changes in the intensity of the geomagnetic field a new more reliable technique has been used to determine the ancient intensity of the earth s magnetic field using samples of baked clay from eight sites in the eastern mediterranean the resultant power spectrum reveals a single strong component with a period of 1430 years the reproducibility of the results obtained with the new method also makes limited archaeomagnetic dating with a precision of between about one and two hundred years between 900 bc and ad 400 possible

climatic solar oceanic and geomagnetic influences on late glacial and holocene atmospheric 14c 12c change late glacial and holocene 14c12c ratios of atmospheric co2 vary in magnitude from a few per mil for annual decadal pertubations to more than 10 for events lasting millennia a data set illuminating 10 to 104 yr variability refines our understanding of oceanic climatic versus geomagnetic or solar forcing of atmospheric 14c12c ratios most of the variance in the holocene atmospheric 14c12c record can be attributed to the geomagnetic millennia time scale and solar century time scale influence on the flux of primary cosmic rays entering the atmosphere attributing the observed atmospheric 14c12c changes to climate alone leads to ocean circulation and or global wind speed changes incompatible with proxy records climate ocean related 14c redistribution between carbon reservoirs while evidently playing a minor role during the holocene may have perturbed atmospheric 14c12c ratios measurably during the late glacial younger dryas event first order corrections to the radiocarbon time scale 12 000 30 000 14c yr b p are calculated from adjusted lake sediment and tree ring records and from geomagnetically defined model 14c histories paleosunspot numbers 100 9700 cal yr b p are derived from the relationship of model 14c production rates to sunspot observations the spectral interpretation of the 14c12c atmospheric record favors higher than average solar activity levels for the next century minimal evidence was found for a sun weather relationship

paleoenvironments from robust loess stratigraphy using high resolution color and grain size data of the last glacial krems wachtberg record ne austria abstract the complex interplay of dust sedimentation pedogenesis and erosion reworking in the formation of loess paleosol sequences lps challenges paleoenvironmental proxies here we show that color and grain size are essential parameters characterizing loess profiles and support robust stratigraphies as a basis for reconstructions in the context of local geo ecological and large scale paleoclimatic evolution detailed paleoenvironmental records from the period since the arrival of anatomically modern humans to the last glacial maximum are scarce in the alpine surroundings the c 7 5 m thick lps krems wachtberg ne austria known for its well preserved upper paleolithic context at a depth of 5 5 m formed between 40 and 20 ka bp by quasi continuous dust sedimentation interrupted by phases of incipient pedogenesis and local reworking the new kw2015 composite is based on three sections studied and sampled at 2 5 cm resolution color and grain size data support a robust stratigraphy for reconstructions of the pedosedimentary evolution the marked transition from oxidized to reduced paleosols of kw2015 around 34 35 ka corresponds to the middle to upper pleniglacial transition as part of a general cooling trend from marine isotope stage mis 3 to 2 intensely modulated by millennial scale climatic fluctuations as recorded in the greenland ice core data the distinct response of kw2015 to these trends highlights that reconstructing lps evolution based on a robust stratigraphy is a prerequisite to paleoenvironmental proxy interpretation

a new method for measuring palaeomagnetic intensities because measurements of palaeomagnetic intensities henceforth palaeointensities are usually time consuming and the success rate only poor say 30 50 many palaeointensity values are based on as few as three experimental results in an attempt to improve on this a technique has been developed using automated equipment which is faster and which can detect alteration of a sample during measurement allowing the experiment to be terminated and another sample to be tried the technique described here has been used on a collection of ancient bricks and the results show the palaeofield at cambridge england to have decreased from about 49 t in ad 1511 to 42 t in ad 1758 in good agreement with results using shaw s method

paleomagnetic recording fidelity of nonideal magnetic systems a suite of near identical magnetite nanodot samples produced by electron beam lithography have been used to test the thermomagnetic recording fidelity of particles in the 74 333 nm size range the grain size range most commonly found in rocks in addition to controlled grain size the samples had identical particle spacings meaning that intergrain magnetostatic interactions could be controlled their magnetic hysteresis parameters were indicative of particles thought not to be ideal magnetic recorders however the samples were found to be excellent thermomagnetic recorders of the magnetic field direction they were also found to be relatively good recorders of the field intensity in a standard paleointensity experiment the samples intensities were all within 15 of the expected answer and the mean of the samples within 3 of the actual field these nonideal magnetic systems have been shown to be reliable records of the geomagnetic field in terms of both direction and intensity even though their magnetic hysteresis characteristics indicate less than ideal magnetic grains

re evaluation of greek archaeomagnitudes a new technique is used to determine the secular variation of the geomagnetic ancient field in athens the results indicate that published greek archaeomagnitudes were seriously affected by alteration it is shown that all intensities obtained using modifications of the thellier method may be affected by alteration and are therefore suspect

loess magnetic fabric of the krems wachtberg archaeological site the loess sediment embedding the main gravettian layer at the krems wachtberg archaeological site facilitates exceptional preservation to gain insight in the sedimentation process before and after the palaeolithic settlement the magnetic fabric preferential orientation of magnetic particles of loess of the krems wachtberg site was investigated magnetic fabric properties clearly show an eolian origin of the loess but may indicate some relocation in the metre above the cultural layer the magnetic fabric properties can be divided into three intervals the top interval shows lowest foliation and inconsistent magnetic fabric directions the middle interval around the main cultural layer shows low foliation but a clear preferential nw se direction of the lineation this lineation is interpreted as preferential direction of the eolian loess accumulation from the southeast the interval below 0 5 m underneath the main find horizon shows a northeast southwest lineation but an imbrication suggesting that sediment accumulation occurred at 90 to this direction similar to the interval around the find horizon

micromagnetics and magnetomineralogy of ultrafine magnetite inclusions in the modipe gabbro 1 iron oxide inclusions in pyroxene crystals from the modipe gabbro botswana have been studied to determine their recording fidelity hysteresis parameters first order reversal curves isothermal remanent magnetization acquisition curves and thermomagnetic data all indicate that the iron oxide occurs as stoichiometric magnetite in the form of single domain and or small pseudo single domain particles using distributions for the grain shape and nearest neighbor spacings determined from optical micrographs as input a first order reversal curve forc diagram was simulated using a numerical micromagnetic model the simulated forc diagram was found to closely match the measured forc distributions analysis of the interaction fields in the model found that the standard deviation of the interaction field distribution was 2 7 mt compared to a bulk coercivity of 20 mt suggesting that the majority of particles are unlikely to be affected by magnetostatic interactions thellier analysis of the samples induced with an initial laboratory thermoremanence yielded near perfect behavior it is suggested that the modipe gabbro dated at 2784 0 1 5 2 ma is potentially an ideal recorder of the geomagnetic field

an improved methodology for thellier type paleointensity determination in igneous rocks and its usefulness for verifying primary thermoremanence we propose a new methodology for thellier type paleointensity experiments in standard paleointensity experiments the blocking temperatures of most stable remanences are often not reached before thermal alteration of magnetic mineralogy begins and subsequent data have to be discarded we emphasize that when alteration begins at low temperature and continues throughout the experiment which then fails in standard analyses the resulting unblocking temperature tub spectrum of the alteration product does not necessarily overlap with the whole tub spectrum of natural remanent magnetization nrm because tub depends on physical characteristics of the new grains not the temperatures at which they were formed nrm may survive in an uncontaminated higher tub window if alteration remanence only has low tub then partial thermoremanent magnetization ptrm checks at temperature step tj 1 can be used to correct for alteration that has occurred at tj and furthermore thermal demagnetization of a full trm acquired in the laboratory at the end of the progressive thellier thellier experiment should reveal the true uncontaminated tub spectrum of the nrm in higher temperature intervals we propose a new experimental sequence which allows monitoring and correction of alteration and provides two semi independent estimates of palaeointensity in the circumstances described above we illustrate the issues involved through new experimental work on igneous rocks from a paleozoic charnockitic syenite where we unravel trm from multidomain isothermal remanence despite massive alteration during laboratory heating finally we point out the value of these experiments for verifying primary trm in igneous rocks indicating properties that distinguish trm from other remanence

some evidence for sharp changes in the archaeomagnetic intensity variation during the last 2000 years abstract an assessment of archaeomagnetic intensities from greek and bulgarian data sets during the last 2000 years indicates sharp changes in their variation particular emphasis is given to the reliability of these data and the results are discussed in terms of a latitude effect

paleointensity of the earth s magnetic field recorded by two late quaternary volcanic sequences at the island of la reunion indian ocean a paleomagnetic study has been undertaken on two late quaternary volcanic sequences from the piton de la fournaise volcano island of la reunion in order to provide absolute paleointensities of the earth s magnetic field from a site in the southern hemisphere the pattern of secular variation recorded by both sequences clearly indicates that the extrusion rate of the lava flows was not constant with time a detailed investigation of the magnetic properties of the samples was carried out in parallel with paleointensity experiments which were performed with the thellier method samples with minimum overprint composed by single domain or pseudo single domain magnetite showing good thermal stability and a narrow blocking temperature spectrum were the most successful during thellier s experiments values of the paleofield strength from 19 to 55 mt have been obtained on 23 flows among the 30 which were sampled few variations 7 5 9 9 1022 a m2 are observed in the virtual dipole moments vdms determined on the youngest sequence 5 12 ka those values are within the range of fluctuations of the worldwide variations of vdms for this period on the other hand data from the oldest sequence 82 98 ka are the first paleointensity values obtained in that time period and the observed vdms extend from 4 1 to 8 8 1022 a m2 these results suggest that for this time interval the field did not depart from its average behavior

geochemistry geochronology and petrogenesis of a late precambrian 590 ma composite dike from the north eastern desert of egypt late precambrian 575 600 ma igneous activity in the north eastern desert of egypt produced large volumes of compositionally bimodal magmas a single composite dike was studied to further examine petrogenetic relationships between andesitic and rhyolitic melts the dike consists of 1 5 2 m of andesite on either side of a 5 6 m wide rhyolite core contact relations indicate that the andesite and rhyolite simultaneously existed as porphyritic liquids wholerock rb sr dating indicates an age of 591 ma but with considerable scatter andesite and rhyolite had similar initial87sr 86sr of 0 7032 2 indicating derivation from a low rb sr source either the upper mantle very young upper crust or depleted lower crust the composition of the andesites on either margin cannot be distinguished these are very similar to andesites of the dokhan volcanics of similar age correspondingly the rhyolite is compositionally similar to the epizonal pink granites this dike and others like it represent hypabyssal feeders for the extrusive and shallow intrusive members of the north eastern desert bimodal suite

triassic shoshonites from the dolomites northern italy alkaline arc rocks in a strike slip setting triassic igneous rocks of the dolomites are typical shoshonites with high k2o sio2 and k2o na2o ratios and low fe contents they have mid ocean ridge basalt like abundances of high field strength elements but are highly enriched in large ion lithophile lil elements rb sr ba k the effects of crustal contamination and fractional crystallization have been superimposed on initial lil element enrichment lavas of similar composition occur in papua new guinea fiji the absaroka mountains and the eolian islands these suites are all associated with destructive plate margins but were not erupted until after subduction had ceased examination of mediterranean paleogeography indicates that no subduction event which could have given rise to the shoshonites of the dolomites occurred during the triassic in fact the tectonic setting at the time of eruption of the lavas was probably one of strike slip faulting the suite may have inherited its arc signature from permo carboniferous subduction of the ocean between laurasia and gondawanaland prior to the hercynian orogeny

the mis 3 2 transition in a new loess profile at krems wachtberg east a multi methodological approach abstract local to regional paleoenvironmental reactions to past climate changes are preserved in loess paleosol sequences lps in order to extract this information we used a multi methodological approach in the upper paleolithic site of krems wachtberg east in lower austria detailed field studies and high resolution geochemical colorimetric and granulometric analyses help to understand the interplay between soil formation loess accumulation and surface processes in comparison to the main profile excavation of krems wachtberg 2005 2015 it can be stated that osl and 14c ages as well as the archeological stratigraphy of both profiles are comparable however pedogenic features are more evident at krems wachtberg east the new investigations show that well established weathering indices do not clearly trace interstadial soil formation in the studied profile apart from this fact single specific elements like fe and mg react more sensitive to initial pedogenic processes weak pedogenesis can further be evidenced by quantitative spectrophotometric results the latter is also capable of refining and supporting the stratigraphy pedology based on field analyses as a general rule next to loess also initial soil horizons of the mis 3 are remarkably rich in primary carbonates indicating that soil formation took place in an alkaline environment due to the fact that hydrolysis of feldspars could not clearly be detected by the application of pedochemical indices soil formation was probably limited to the oxidation of iron bearing minerals and weak carbonate leaching these phases of favorable climatic conditions in terms of pedogenesis were terminated by increasing dust input towards the onset of mis 2 the eolian deposits are overprinted during reducing conditions in soils and or modified by colluvial processes altogether weak pedogenesis can be reliably detected using a multi methodological approach which leads to enhanced paleoenvironmental interpretations the osl ages put the profile in a range of 41 to 30 ka we present a tentative correlation of the studied loess profile to the record of the north greenland ice core project ngrip for the part of the profile where osl and 14c complement each other

a comparison of a quasi perpendicular method of absolute palaeointensity determination with other thermal and microwave techniques abstract we describe test and explain the relative effectiveness of six thermal and microwave techniques of absolute palaeointensity determination applied to lava samples from mount etna sicily that acquired their thermoremanence trm in a known geomagnetic field the application of a single alternating field demagnetisation treatment prior to each measurement in a standard thellier experiment is demonstrated to be beneficial increasing the quality of the results and making the analysis simpler a new quasi perpendicular qp method dramatically improves the linearity of arai plots by reducing or altogether eliminating non ideal effects due to multidomain md grains two broad types of sample were encountered by this study and the qp method is the only one capable of producing accurate measurements from them both its ease of use speed and increased reliability should allow it to replace standard double heating methods in studies such as these where laboratory alteration can be detected by other means than ptrm checks the results of experiments performed using a microwave palaeointensity system provide further proof that the microwave de magnetisation process is equivalent to conventional thermal excitation they also demonstrate that microwave experiments are subject to the same risks as conventional experiments when performed on samples containing md grains the behaviour of the samples in both the thermal and microwave experiments is in good agreement with a recently proposed model of md trm which is based on first order symmetry of the remagnetisation process

paleoenvironmental fluctuations as recorded in the loess paleosol sequence of the upper paleolithic site krems wachtberg abstract the loess paleosol sequence of krems wachtberg is famous for its archeological findings above all its gravettian infant burials it represents a complex system of paleoclimatic fluctuations which is nearly complete and thus enables the correlation with global paleoclimatic records this sequence comprises activity phases with dominant eolian and partly erosional processes as well as stable short periods of weak pedogenesis periglacial environment with drier climate conditions and high eolian sedimentation rates characterize the upper part of the sequence and in periods with lower sedimentation rates cryosols and permafrost induced structures are developed although the krems wachtberg site is situated at a slope position intensive erosional phases events can be excluded the basal parts of the sequence show signs of decalcification bioturbation organic inclusions as well as changes in element distribution pedogenic horizons are partly overprinted by permafrost related structures and are disturbed by redepositional processes to a minor degree remarkably the archeological horizon is not affected by permafrost in contrast to the layers below and above the focus of this study is deciphering stratigraphy by a combination of paleopedological sedimentological analyses with rock magnetic analyses on the chronological scale the sequence records a timespan from 35 ka to 20 ka altogether there is evidence of five pedogenic units and one archeological layer which are correlated with the greenland interstadials gi 7 to gi 2 however an equivalent of a mis 3 interstadial soil comparable with the lohne soil or stillfried b soil could not be detected

our oldest children age constraints for the krems wachtberg site obtained from various thermoluminescence dating approaches abstract we present several approaches to directly date the prehistoric human activity of lighting a fire at the early gravettian infant burial site of krems wachtberg austria by thermoluminescence tl methods blue thermoluminescence b tl from polymineral fine grain and orange red thermoluminescence r tl from fine grained quartz separates both extracted from the baked loess immediately underlying the hearth were employed the b tl dating followed the classic multiple aliquot additive dose maad protocol for r tl dating the multiple aliquot regenerative mar and a shortened single aliquot regeneration sar protocol were tested all thermoluminescence ages obtained agree within 1 uncertainties and assign a weighted mean age of 33 9 2 3 ka to the last use of the hearth and by inference to the infant burial anomalous fading is precluded due to the agreement of results from all luminescence protocols as well as with independent dating methods the tl ages are consistent with calibrated radiocarbon ages on associated charcoal osl dating of the sediment deposition and with age estimates obtained by two magnetic dating approaches

multi protocol palaeointensity determination from middle brunhes chron volcanics datong volcanic province china a full vector palaeomagnetic analysis of basalts from the datong volcanic province china has been carried out to constrain the orientation and magnitude of the geomagnetic field during the mid brunhes chron at approximately 0 41 ma palaeomagnetic directions were determined using thermal demagnetization palaeointensity information was determined using a multi protocol approach 1 a thellier type protocol 2 the multi specimen parallel differential partial thermoremanence method and 3 the wilson method the most consistent data set was obtained with the wilson method whilst similar average values with wider data scatter were obtained with the thellier method higher values were obtained with the multi specimen method we suggest that consistency of results from the different protocols which access different sections of the blocking unblocking spectra provide a useful test of the robustness of palaeointensity estimates a mean virtual dipole moment of 5 4 0 6 1022 am2 was determined which agrees well with coeval values from the pint database and with the higher average palaeointensities for the mid brunhes chron indicated by more continuous sedimentary relative palaeointensity records

upper palaeolithic occupation in the wachtberg area of krems the evidence of surveys sections and core samples abstract the classic upper palaeolithic location of the wachtberg in krems eastern austria features a multitude of exposures in a limited area of about 50 000 m 2 in addition to gravettian sites which have been investigated in detail in the course of recent years using modern methods there are the records of old excavations several documented sections as well as a considerable number of core samples displaying heterogeneous documentation standards this paper provides an overview of these different sources of information and aims at synthesizing the data for a comprehensive understanding of the local loess sedimentation and palaeolithic occupation

loess deposits and the conservation of the archaeological record the krems wachtberg example recent archaeological excavations at the upper palaeolithic open air site of krems wachtberg in eastern austria exposed a late pleistocene loess sequence an interdisciplinary sampling strategy was applied to the 8 m high north profile the extraordinary conservation of a gravettian living floor with several complex features is discussed in this paper

late precambrian rifting and crustal evolution in the northeastern desert of egypt basement exposures along the northwestern flanks of the gulf of suez record the rapid formation of continental crust during the interval 670 550 ma a variety of field petrographic petrologic and isotopic considerations indicate that this episode of crust formation took place in an extensional tectonic setting analogous to that of the late paleozoic oslo rift of norway crustal evolution in this region thus contrasts with other regions of the afro arabian shield where the crust appears to have been formed by convergent margin accretionary processes and collisional tectonics this imposes new constraints on our understanding of late precambrian crustal evolution

geochemical characterization of pan african dyke swarms in southern sinai from continental margin to intraplate magmatism abstract the chemical and mineralogical features of three pan african dyke swarms occurring in the wadi feiran area southern sinai have been examined two swarms striking approx 35 exhibit calcalkaline chemical properties the oldest s1 can be related to calcalkaline rocks from active continental margins by means of incompatible element plots displaying negative nb ta anomalies they dykes were emplaced synchronously with post orogenic alkaline granites to which they cannot be assigned chemically a second dyke generation l1 with the same strike shows apparent similarities with continental flood basalts e g columbia river basalts indicating a growing contribution of continental components to melt chemistry subduction related features are displayed by negative nb ta anomalies the youngest dyke swarm s2 striking approx 135 and crosscutting s1 displays transitional to mildly alkaline properties without negative nb ta anomalies its chemistry is fully consistent with intraplate basalts of continental areas the source regions of the three swarms cannot be related via assimilation of crustal material because decreasing lile percentages coupled with increasing amounts of nb and ta cannot be explained by this means the overlap of m values of rocks to be found with the three swarms indicates the unlikeliness of a development of the three magmas via fractional crystallization the emplacement of two totally different types of dykes in the wadi el sheikh area requires a source region which is either chemically inhomogeneous in a more or less vertical scale or changing its composition and melting conditions with time although the dykes were emplaced in an extensional tectonic setting the subcrustal lithosphere still produced calcalkaline melts documenting its subduction related magmatic history

a mineral magnetic study of some pottery samples possible implications for sample selection in archaeointensity studies abstract we have related the mineral magnetic properties of some archaeological samples to the quality of the paleointensity data that they produce we find that samples which have broad unblocking temperature distributions and most of their remanences unblocked at intermediate temperatures produce high quality paleointensity data this conclusion is based on a comparative study of pottery samples which had previously produced reliable and unreliable paleointensity data for each sample we determined the magnetic mineralogy and the magnetic domain state in all cases magnetite or titanomagnetite is the primary magnetic carrier with domain states that extend from superparamagnetic to single domain and maybe even to pseudo single domain we believe that the magnetic grain size distribution of these samples produces a broad unblocking temperature distribution the advantage of having such a distribution is that high quality data can be obtained before the onset of the mineralogical changes that can occur at high temperatures with the thellier and thellier method the frequency dependent susceptibility appears to be useful as a non destructive estimator of the unblocking temperature distribution for samples having only magnetite as the magnetic mineral

a preisach method for estimating absolute paleofield intensity under the constraint of using only isothermal measurements 2 experimental testing 1 this paper reports an empirical test of a new nonheating preisach based protocol for determining the absolute ancient magnetic field intensity paleointensity using a selection of synthetic samples and a large suite of modern lavas and pyroclastic lithic samples generally the preisach paleointensity estimates compare favorably with the expected field intensities 1 for the synthetic samples displaying single domain like behavior the method returned the correct result for the known field while multidomain samples yielded an underestimate and 2 averaging 168 post 1850 a d lavas yielded a value 6 within the expected field value these preisach paleointensity estimates are also compared with paleointensity determinations made on the same suite of samples using standard thellier type heating protocols and the nonheating remanence rem method the preisach paleointensity estimates compare favorably for samples that yielded correct thellier type determinations including the synthetic single domain like samples in addition the preisach method produced estimates for cases where the thellier type estimates failed a possible selection criterion was identified median destructive field which was found to improve the paleointensity estimates in some sample suites for the investigated sample set the preisach method was found to be much more accurate than the rem method the importance of cooling rate on the preisach paleointensity estimate is also examined

comment on a j biggin et al a comparison of a quasi perpendicular method of absolute palaeointensity determination with other thermal and microwave techniques earth and planetary science letters 257 2007 564 581 abstract while biggin et al s paper is an important review and critique of palaeomagnetic methods employed at present we point out here that if the grain size selectivity of microwaves is employed instead of just using them to heat the sample alteration can be avoided completely and previously unavailable grain size dependence of the magnetic moment can be recovered

luminescence based loess chronostratigraphy of the upper palaeolithic site krems wachtberg austria abstract the loess section krems wachtberg lower austria is well known for its upper palaeolithic find layer which contains a double and a single infant burial the layer containing the grave archaeological horizon ah 4 4 was dated to 26 580 160 14 c bp einwogerer et al 2006 corresponding to ca 31 ka cal bp and is embedded in an 8 m thick loess sequence in order to provide a chronostratigraphy of the entire section 38 samples for luminescence dating were taken at high resolution from below and above the find layer the samples were dated using the quartz coarse grain fraction the quartz fine grain fraction and or the polymineral fine grain fraction the resulting ages are in correct chronostratigraphic order and in case samples were measured with different protocols agree within errors with each other and with the radiocarbon age of the find layer the polymineral fine grain ages are systematically slightly lower than the quartz ages although no fading could be detected in laboratory experiments loess deposition at the site commenced ca 40 ka ago and reaches up to ca 22 ka the ages indicate nearly continuous loess sedimentation throughout this time span short breaks in sedimentation probably exist but cannot be resolved due to the uncertainties of luminescence ages

hearth side bone assemblages within the 27 ka bp krems wachtberg settlement fired ribs and the mammoth bone grease hypothesis besides two human infant burials the most important evident feature of the recent excavations at the gravettian pavlovian base camp site krems wachtberg is a multi phased hearth with a diameter of almost 1 5 m the feature is part of a compacted living floor which probably represents the interior of a dwelling the hearth contains charcoal mostly burned small bone fragments lithic artefacts in a matrix of ashy sediment and fire modified loess numerous mammoth limb bone flakes and the overall extensively fractured bone assemblages mainly from mammuthus equus rangifer and capra including a considerable portion of cancellous bone pose the question whether bone grease manufacture could have been a possible cause of these patterns the analysis of faunal remains addresses besides the most accurate determinations of species and skeletal position fragment size class proportions green bone fracture frequency the intensity of combustion and spatial distribution patterns while the most frequent species within the living floor is woolly mammoth followed by wild horse reindeer and ibex ungulate and mammoth bone counts are more balanced in the assemblages of the three distinct hearth phases a tendency toward more importance of the ungulates and more intense fragmentation can be observed in the last phase the bones which can be attributed to wild horse show a remarkably different spatial distribution than the mammoth remains generally the patterns suggest that a large part of the bones within the hearth is burned waste partly from fireside consumption for instance of rib meat in contrast abundance and concentration of green fractured mammoth and ungulate limb bones around the hearth is interpreted as primary refuse from marrow procurement strategies to counter resource fluctuations nutritional stress differential use and treatment of animal tissue including the fat within the bones are considered the most important issues for understanding gravettian settlement patterns

a large drop in atmospheric 14c 12c and reduced melting in the younger dryas documented with 230th ages of corals paired carbon 14 14 c and thorium 230 230 th ages were determined on fossil corals from the huon peninsula papua new guinea the ages were used to calibrate part of the 14 c time scale and to estimate rates of sea level rise during the last deglaciation an abrupt offset between the 14 c and 230 th ages suggests that the atmospheric 14 c 12 c ratio dropped by 15 percent during the latter part of and after the younger dryas yd this prominent drop coincides with greatly reduced rates of sea level rise reduction of melting because of cooler conditions during the yd may have caused an increase in the rate of ocean ventilation which caused the atmospheric 14 c 12 c ratio to fall the record of sea level rise also shows that globally averaged rates of melting were relatively high at the beginning of the yd thus these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the mississippi to the st lawrence river triggered the yd event

continuous geomagnetic field models for the past 7 millennia 1 a new global data compilation 1 a global data set of archeomagnetic and paleomagnetic data covering the past 7000 years has been compiled it consists of 16 085 results of inclination 13 080 of declination and 3188 of intensity for the time span 5000 bc to 1950 ad declination and inclination data come partly from existing databases and partly from original literature a new global compilation of intensity data for the millennial scale is included data and dating uncertainties are discussed as we attempted to obtain an internally coherent data set the global distribution of the data is very inhomogeneous in both time and space all the data are compared to predictions from the previous 3000 year global model cals3k 1 this collection of data will be useful for global secular variation studies and geomagnetic field modeling although southern hemisphere data are still underrepresented in particular we will use it in a further study to update and extend the existing global model cals3k 1 the huge increase in data compared to the previous compilation will result in significant changes from current models as we might have missed some suitable data we encourage the reader to notify us about any data that have not been included yet and might fit in as improving our global millennial scale models remains our aim for the future the data files described in this paper are available from the earthref digital archive erda at http earthref org cgi bin erda cgi n 331

the najd fault system saudi arabia and egypt a late precambrian rift related transform system the najd fault system is a complex set of left lateral strike slip faults and ductile shear zones that strike nw se across the precambrian of arabia and egypt this system was developed during the interval 540 620 ma it is up to 400 km wide with an exposed length of 1100 km inferred buried extensions of the najd give it a total length of 2000 km it is the best exposed and may be the largest pre mesozoic zone of transcurrent faulting on earth previous models for the najd fault system suggest it formed as a result of a major late precambrian continent continent collision this model is not preferred here because 1 the lack of evidence for a pre late precambrian continent to the east of the najd fault system 2 the difference between the orientation of the najd fault system and that predicted by slip line theory 3 the younger age of najd movements compared with that of collisional sutures in the arabian shield and 4 lack of evidence for wide spread crustal uplift that would be expected to accompany collision a new model for the origin of the najd fault system accounts for each of these objections the najd fault system formed in response to a broad zone of nw se directed crustal extension that accompanied juvenile continental crustal formation in northernmost afro arabia this model also accounts for the following observations 1 strands of the najd parallel the direction of extension in the north eastern desert of egypt and sinai 2 the timing of the principal rifting movements ca 575 600 ma overlap with those of the najd ca 560 620 ma 3 in spite of observation 2 the najd fault system is not recognized in northernmost afro arabia instead the najd deformation becomes increasingly ductile and these zones are more commonly intruded by sheared and foliated granites as the principal zone of extension is approached the najd fault system thus represents a set of continental transforms developed in response to a major episode of late precambrian extensional continental crust formation in northernmost afro arabia

archeoint an upgraded compilation of geomagnetic field intensity data for the past ten millennia and its application to the recovery of the past dipole moment 1 this paper presents a compilation of intensity data covering the past 10 millennia archeoint this compilation which upgrades the one of korte et al 2005 contains 3648 data and incorporates additional intensity and directional data sets a large majority of these data 87 were acquired on archeological artifacts and the remaining 13 correspond to data obtained from volcanic products the present compilation also includes important metadata for evaluating the intensity data quality and providing a foundation to guide improved selection criteria we show that 50 of the data set fulfill reasonable reliability standards which take into account the anisotropic nature of most studied objects potsherds the stability of the magnetization and the data dispersion the temporal and geographical distributions of this sub data set are similar to those of the main data set with 72 of the data dated from the past three millennia and 76 obtained from western eurasia approximately half of the selected intensity data are associated with at least an inclination value to constrain the axial and full dipole evolution over the past three millennia requires that we avoid any overrepresentation of the western eurasian data we introduce a first order regional weighting scheme based on the definition of eight widely distributed regions of 30 width within which the selected data are numerous enough the regional curves of virtual axial dipole moments vadm and of mixed vadm virtual dipole moments vdm averaged over sliding windows of 200 years and 500 years testify for strong contributions from either equatorial dipole or nondipole components the computation of global vadm and mixed vadm vdm variation curves assuming an equal weight for each region yields a dipole evolution marked by a distinct minimum around 0 b c a d followed by a maximum around the third fourth century a d a second minimum is present around the eighth century a d this variation pattern is compatible with the one deduced from earlier more

revisiting a domain state independent method of palaeointensity determination abstract the use of a domain state independent method the wilson method of acquiring absolute palaeointensities is tested using three sets of historical lavas from mexico italy and iceland the wilson method works by plotting continuous thermal demagnetisation curve data for the original natural remanent magnetisation against those for a laboratory induced thermoremanence by comparing the predicted intensities with the known fields a new empirically derived rejection criterion is proposed that accounts for chemical alteration and improves the accuracy of the palaeointensity estimates the wilson palaeointensity estimates are compared with palaeointensity determinations made on sister samples using standard thellier type heating generally the wilson palaeointensity estimates compare favourably for samples that yielded technically correct thellier type determinations however at one locality the wilson method did not yield any estimates due to severe chemical alteration in contrast it was still possible to determine palaeointensity estimates from the lower temperature thellier data to assess the wilson palaeointensity protocol s ability to return a correct estimate for a true multidomain system a synthetic multidomain magnetite sample was imparted with a thermoremanent magnetisation the wilson protocol returned the correct palaeointensity within error in contrast the thellier type protocol failed as the wilson method is significantly faster than thellier type methods it is suggested that the wilson method should be tried as a first approach in palaeointensity studies or for samples dominated by multidomain material

alteration of the coercivity spectrum and paleointensity determination a restudy of 13 bricks from a 19th century kiln using the shaw af demagnetization method of paleointensity determination revealed alteration of the magnetite carrying natural remanent magnetization nrm during heating to the curie point anhysteretic remanences before heating arm1 and after heating arm2 had similar intensities but the arm2 coercivity spectrum was softer than the arm1 spectrum the coercivity spectrum of thermoremanence trm softened in a similar way after heating we therefore calculated a corrected trm trmc arm1 arm2 trm at each af demagnetization step the nrm vs trmc plot was in most cases more nearly linear than the original nrm vs trm plot however the paleointensities determined using uncorrected total nrm trm ratios 57 t and using our trmc values 55 5 t agreed equally well with a recent thellier method determination of 56 t by aitken and others grain size alteration of the magnetites has changed their fundamental trm arm ratios as well as their coercivities making our correction procedure untrustworthy lack of significant changes in trm or arm coercivity spectra after heating is evidence of minimal grain size alteration and remains the best criterion for reliable shaw method paleointensities

the early gravettian in a marginal area new evidence from sw poland abstract previous studies on the gravettian in central europe did not pay much attention to the issue of the marginal areas occupation because the main research interest was placed on analysis of remains from the area of classic refugia the middle danube valley or southern moravia consequently little is known about the mechanisms associated with occupation of areas located to the north of the carpathians and the sudetes both in terms of chronology as well as system of mobility the results of excavations at the open air site in henrykow sw poland presented in this paper indicate that attempts of exploitation of upland territories located to the north of the mountain chains started very early i e in the so called early gravettian period this is indicated by radiocarbon dating of charcoal samples 28 5 31 5 ka bp from the site these dates were confirmed by dating of mineral deposits using the osl method ca 29 ka based on geoarchaeological studies the period of human stay at the henrykow site plausibly associated with development of the soil complex of the komorniki l1s1 stillfried b lohner boden type archaeological data indicate that the stay was linked with hunting practices the features of the henrykow site typical for marginal occupation suggest that during the visit tool kits were reconstructed stocks were replenished and fire was used the dataset suggests that traces from henrykow should be treated as a result of pioneering expeditions this mobility probably never had a more stable character as in the later period of the gravettian complex development

evaluation of the multispecimen parallel differential ptrm method a test on historical lavas from iceland and mexico summary obtaining reliable geomagnetic palaeointensity pi estimates is still a difficult objective most common techniques in pi studies are based on various modifications of the thellier method but high failure rates and large uncertainties are common furthermore only rocks which obey stringent criteria are assumed to yield faithful pi estimates in general magnetic particles must be of single domain size the magnetization must be a thermoremanent magnetization and chemical alteration of magnetic carriers must be avoided during the laboratory experiment recently a new method for obtaining pis was proposed which on the grounds of results from two historic lavas and three simulated experiments is assumed to be independent of magnetic domain state this method uses multiple samples subjected to only one heating step at moderate temperatures here we present a test of the multispecimen parallel differential ptrm method on 11 historical lavas from iceland and mexico from which the actual field intensity is known either from magnetic observatory data or from magnetic field models our results show that the majority of pi estimates after the multispecimen parallel differential ptrm method yielded results that are very close or indistinguishable within the range of error from the expected intensity and thus largely confirm the findings from the initial study however there is in general a small overestimate which we show is associated with multidomain material when compared to a thellier type pi experiment carried out on sister samples from five icelandic lava flows the average multispecimen pi is closer to the actual field intensity samples from one lava characterized by low curie temperatures failed the thellier approach due to laboratory induced alteration but here the multispecimen method returned a reasonable pi even though there is evidence that the method is not entirely independent of magnetic domain state as previously proposed we regard this method as a valuable alternative in future pi studies

paleointensity results from the late archaean modipe gabbro of botswana 1 rock magnetic and thellier thellier coe paleointensity results are reported for a new collection of samples from the 2 78 ga modipe gabbro of botswana the magnetic properties are very favorable leading to an unusually high success rate and a well constrained result of 36 40 t 95 confidence interval we discuss the long standing problem of allowing for the enormous differences between the natural and laboratory cooling rates and apply a temperature dependent correction derived from first order reversal curve forc data whereas pure single domain sd corrections often lead to quite large decreases in paleointensity estimates sometimes exceeding 50 we find a modest increase of about 10 the earth s magnetic dipole moment in the late archaean is thereby estimated to have been 6 1022 am2

geochemistry mineral chemistry and petrogenesis of a neoproterozoic dyke swarm in the north eastern desert egypt dyke swarms traverse neoproterozoic rocks in the hawashiya region in the extreme northern part of the eastern desert of egypt they are a suite of basaltic andesite and andesite mafic dykes and dacitic and rhyolitic felsic dykes the mafic dyke suite is more abundant in the younger granites 577 6 ma than in the older granitoids 614 ma in which the felsic dykes are the most common the dyke swarms trend predominantly ne sw and the felsic dyke suite is older than the mafic dyke suite both dyke suites are calc alkaline alkaline dykes are rare and are relatively poor in tio 2 and nb but enriched in the incompatible elements and hfse the felsic dyke suite is enriched in ree and is strongly lree fractionated relative to the mafic dyke suite although the hawashiya dykes were emplaced at the end of the neoproterozoic era in an extensional tectonic setting they have geochemical characteristics that are consistent with a subduction related regime these chemical signatures were inherited from the lithospheric rocks that produced their host hawashiya granitoids the felsic dyke suite magma may be derived from crustal rocks essential source component by partial melting the mafic dyke suite magma was generated from a lithospheric mantle and has undergone fractional crystallization of plagioclase amphibole clinopyroxene and magnetite as documented by major and trace elements fractionation modelling