origin of maghaemite in chinese loess deposits aeolian or pedogenic maghaemite and magnetite common ferrimagnetic minerals in surficial soils have physical properties which are similar except for the thermal instability of the former utilising this exception a study of thermomagnetic properties has been made to systematically separate these two magnetic components in loess and palaeosol samples from the upper parts of the luochuan section of the central chinese loess plateau this investigation has shown that although maghaemite thermally unstable component occurs in greater amounts in palaeosols ms 0 0187 am2 kg 1 1 1 than in loess units ms 0 0156 am2 kg 1 1 1 in relative terms its contribution to the ferrimagnetic component of magnetisation is higher in the loess units ms 32 2 2 0 than the soils ms 23 5 3 7 such an observation suggests that much of the maghaemite component originates in the aeolian source area with some addition of pedogenic maghaemite occurring in the palaeosols

can the magnetic susceptibility record of chinese red clay sequence be used for palaeomonsoon reconstructions red clay underlying the loess palaeosol sequences on the chinese loess plateau is an eolian deposit there is a controversy over whether magnetic susceptibility chi variations in red clay sequence can be used as an indicator of summer palaeomonsoon intensity this study investigates the magnetic mineralogy magnetic concentration and magnetic grain size distribution of jiaxian red clay with multimagnetic methods our results indicate that the magnetic properties of jiaxian red clay are similar to those of the quaternary loess palaeosol sequences and ultrafine ferrimagnetic grains produced during pedogenesis are responsible for an increase in susceptibility therefore the chi enhancement mechanism of red clay is similar to that of the overlying loess palaeosol sequences this paper explores chi variations in the red clay sequence through spatial and temporal analysis the susceptibility variation of six sites along a nne to ssw transect correlate to palaeoclimatic cycles so chi can be used to trace the summer palaeomonsoon intensity from a spatial perspective however a simple loess derived calibration function cannot be used to quantitative reconstruct the palaeomonsoon intensity variations thought time an adjusted calibration function for palaeosols from red clay sequence needs to be developed so that chi can be used to quantitative reconstruct palaeomonsoon intensity further study is necessary to develop such a transfer function

magnetism of loess palaeosol sequences recent developments abstract investigation of the global loess record primarily as a palaeoclimatic archive continues unabated one important aspect of this research effort is the determination of the magnetic properties of the loess itself and of the palaeosols developed within it in earlier work these have provided a record of major long term past climatic changes however recent studies are now revealing sub milankovitch signals with teleconnections from the chinese loess plateau clp to the greenland and antarctic ice caps as well as to climate related events in sediments recovered from the north atlantic these high resolution profiles cover to the last 130 000 years however progress is also being made in extending the record down below the loess sensu stricto of the clp into the so called red clay so that the aeolian record can now be carried back beyond 7 ma bp several authors have attempted to obtain quantitative estimates of palaeoprecipitation by comparing magnetic susceptibility of palaeosols with values for modern soils although the broad picture is qualitatively clear wetter interglacials dryer glacials the actual quantitative values provided by the various techniques differ significantly in the classic chinese sites palaeosols are always magnetically enhanced due to in situ pedogenic processes however evidence is now emerging to indicate that this is not the only magnetoclimatological model in cases such as siberia where wind vigour dominates over pedogenesis the opposite pattern is found with magnetic susceptibility minima in palaeosols this also occurs in situations where the sediments are water logged for significant amounts of time leading to gleying and concomitant loss of magnetic minerals the use of magnetic remanence as a geomagnetic polarity clock requires caution early interpretations were acceptable for establishing broad chronological control however recent scrutiny suggests that remanence lock in may be delayed by as much as 20 000 years furthermore synthetic magnetostratigraphies modelled on the basis of realistic sediment characteristics indicate that there are limits to the amount of geomagnetic detail likely to be resolved this seems to be the case for the blake event which manifests itself in a very variable way at different sites in the clp

quantitative estimates of pedogenic ferromagnetic mineral formation in chinese loess and palaeoclimatic implications abstract the quasi continuously deposited loess sediments of the central chinese loess plateau constitute one of the most complete and long lasting records of quaternary palaeoclimate on land much of this record has been uncovered by measurement and interpretation of the magnetic properties of the loess the polarity of natural remanent magnetization has provided absolute age dates by correlation with the geomagnetic polarity time scale magnetic low field susceptibility has been used to reconstruct the cyclic changes of pleistocene palaeoclimates although the origin of the signal is still poorly understood from comparison with the 10 be concentration throughout the sequence we are able to determine the contributions to susceptibility from inherited and authigenic sources for the last 130 ky since the production of authigenic magnetite is directly related to regional precipitation annual palaeoprecipitation rates can be calculated palaeoprecipitation rates similar to present day rates are derived for oxygen isotope stage 5 including the last interglacial in contrast cold periods corresponding to oxygen isotope stages 2 and 4 experienced negligible precipitation the beginning and end of the time interval represented by oxygen isotope stage 3 however was characterized by short episodes when precipitation exceeded the holocene average

assessment of the palaeoclimate during 3 0 2 6 ma registered by transition of red clay to loess palaeosol sequence in central north china abstract a continuously accumulated section the yanyu section of red clay and loess palaeosol sequence from the southernmost chinese loess plateau was selected for this study of palaeoclimate of the late pliocene to early pleistocene period termination of the red clay accumulation and onset of loess deposition was coincident with the beginning of extensive northern hemisphere glaciation at 2 6 ma field observations and compositional analyses suggest an aeolian origin for the red clay much like the processes experienced by the loess palaeosol sequence pedogenic analysis indicates that the late pliocene red clay first experienced complete decalcification and illuviation mechanical translocation of clays in all horizons including the present carbonate precipitation zones but other chemical alterations have been rather weak and even weaker than experienced by the overlying loess derived palaeosols in great contrast to the pleistocene climate characterised by frequent and large amplitude fluctuations between cold dry and warm wet a relatively steady warm dry climate condition is implied for the late pliocene dustfall rate assessment indicates a much lower accumulation rate during the late pliocene than in the early pleistocene in agreement with a notable systematic coarsening from the red clay to the overlying loess and palaeosols together these features suggest that the dust transport agent the northwesterly winds were weaker over the late pliocene the transition from red clay to loess possibly marked a significant and rapid shift in the climatic system in east asia

late pliocene pleistocene changes in mass accumulation rates of eolian deposits on the central chinese loess plateau 1 late pliocene pleistocene changes in the mass accumulation rates mars of eolian deposits on the central chinese loess plateau clp are reconstructed from measured bulk sediment densities combined with sedimentation rates calculated for two loess red clay sequences the reconstructed mars demonstrate that over the past 3600 kyr distinct aridity humidity fluctuations occurred over glacial interglacial timescales and these were superimposed on a gradual long term drying trend comparisons of the clp mar record with the mar and 18o records for marine sediments suggest that the development of northern hemisphere ice sheets since the late pliocene has played a part in increasing the aridity of central asia in addition the phased uplift of the himalaya tibetan plateau evidently had a profound influence on the aridity of central asia this was mediated by variations in the east asian monsoonal circulation correlations among dust records from ice cores marine sediments and terrestrial loess over the last several glacial cycles provide compelling evidence that glacial periods are characterized by higher and more variable dust fluxes than interglacial intervals synchronous changes in the mar grain size and 18o records reveal dynamic linkages between asian interior aridity paleowind intensity and ice volume after the onset of major northern hemisphere glaciations

revisiting the stratigraphic position of the matuyama brunhes geomagnetic polarity boundary in chinese loess article i nfo it is commonly accepted that the climate records in chinese loess can be correlated well with that in marine sediments however discrepancies for the stratigraphic position of paleomagnetic polarity reversal boundary seriously restrict an accurate teleconnection between these two archives for example the exact stratigraphic position of the whole matuyama brunhes mb transitional polarity zone remains uncertain in chinese loess in this study an accurate transitional zone of the mb reversal from the mangshan profile southeast margin of the chinese loess plateau clp was statistically determined using multiple subsets of parallel samples by integrating results from the central clp the whole mb transitional zone is consistently located across the pedostratigraphic and climatostratigraphic transitional zones between s8 and l8 over a wide region of the clp this conclusion further supports that the paleosol unit s8 should be teleconnected to the marine oxygen isotope stage 19 rather than 21 and thus unambiguously supplies an accurate age control in constructing a new loess time scale

preliminary magnetostratigraphy of the red clay underlying the loess sequence at baoji china magnetic remanence and bulk susceptibility measurements are reported from 93 samples spanning the uppermost 27m of the red clay underlying the loess sequence at baoji shaanxi province china if a new previously undetected short about 20ka excursion or reversed interval near 3 3ma be accepted then a reasonable fit to the standard time scale emerges a linear accumulation rate of 1 5cm ka is implied and the correlation coefficient is 0 992 no significant hiatus occurs between the red clay and the overlying loess so the 27m investigated reach back to about 4 3ma fourier analysis of the bulk susceptibility data yields a strong peak near 400ka in agreement with astronomical calculations of the orbital parameters responsible for climatic forcing

preliminary magnetostratigraphy of a thick eolian red clay loess sequence at lingtai the chinese loess plateau magnetic remanence and bulk susceptibility measurements are reported for a 305 m eolian loess red clay sequence at lingtai the chinese loess plateau polarity zonation defined by about 680 remanence data yields a basal age of about 7 05 ma for the section which represents the oldest wind blown dust deposited continuously in north central china during the late cenozoic the resultant magnetostratigraphic scheme implies a nearly linear accumulation rate about 2 98 cm ka of atmospheric dust on the loess plateau during the period of 7 05 to 2 58 ma comparison of the bulk susceptibility record with the pedogenic characteristics of the red clay observed in the field suggests that magnetic susceptibility in the red clay is not as useful as in the loess soil sequence to indicate summer monsoon variations

the chinese loess in xifeng i the primary study on magnetostratigraphy of a loess profile in xifeng area gansu province summary 1848 specimens were collected systematically from about 900 horizons in the loess profile of xifeng gansu province china the magnetostratigraphy is established on the basis of the palaeomagnetic results after thermal cleaning usually at 300 c this result has been found to be generally consistent with previous work in luochuan the susceptibility varies regularly with the appearance of loess and palaeosol in the profile and thus could be used as a criterion to classify the loess and palaeosol sequence

grain size and accumulation rate records from late cenozoic aeolian sequences in northern china implications for variations in the east asian winter monsoon and westerly atmospheric circulation we attempt to reconstruct the history of westerly and monsoonal circulations in northern china using variations in sediment grain size and accumulation rate at four loess sections in the central chinese loess plateau the initiation of aeolian accumulation at about 7 6 ma in the main part of the chinese loess plateau probably marked the onset of the monsoonal circulation both the monsoonal and westerly circulations weakened from 7 6 to 5 2 ma subsequently the monsoonal circulation strengthened progressively from 5 2 ma to the present in addition the westerly circulation strengthened from 5 2 to 0 6 ma but then weakened thereafter and especially during the last 0 6 ma comparison of our aeolian records and the deep sea sediment record suggests that the strengthening trends of the monsoonal and westerly circulations were associated with the progressive development of global ice sheets during the late cenozoic abrupt changes of both the monsoon and westerly circulations occurred at 7 6 3 4 and 1 2 0 9 ma together with a weakening trend of the westerly circulation in the last 0 6 ma and are interpreted as the consequence of the episodic uplift of the tibetan plateau spatial differences in the grain size characteristics amongst the four sections suggest that the circulation intensity and variability decreased from west to east across the loess plateau due to the topographic effect of the tibetan plateau in addition some spatial differences may have been the result of local topographic effects c 2008 elsevier b v all rights reserved

magnetic stratigraphy constraints on the matuyama brunhes boundary recorded in a loess section at the southern margin of chinese loess plateau although the matuyama brunhes boundary mbb in the chinese loess plateau clp is very important in reliably correlating quaternary loess with other sediments in the world particularly with marine and polar ice cores its exact stratigraphic position remains controversial previous investigations usually placed the mbb between paleosol unit s8 and loess unit l8 in various locations to better understand the spatial differences in the mbb position a high resolution paleomagnetic study was conducted in a loess section of the lantian basin at the southern margin of the clp the results show that the mbb is situated in the middle of the relatively weak paleosol unit s7 consistent with a recent report on the mbb based on a be 10 study from the xifeng and luochuan loess sections of the central clp however the regional anomalously low magnetic susceptibility in paleosols s7 and s8 indicates that it is more reliable to determine the paleoclimate boundaries between loess and paleosol horizons of this segment with median grain size then the mbb in the yushan section can be correlated with the bottom of paleosol s7 corresponding to the older part of interglacial marine isotope stage 19 this result temporally reconciles the striking discrepancy of the position of the mbb recorded in between loess and other typical sedimentary sequences and further confirms that the stratigraphic position of the mbb could spatially vary to a certain extent due to regional sedimentary or paleoclimatic conditions in the marginal areas of the clp in the yushan section the high frequency variations of paleomagnetic directions during a long period of similar to 31 ka before the mbb however could not be attributed to a genuine response to the true geomagnetic behaviour moreover the climate offset defined by the magnetic susceptibility and median grain size of the section can be preliminarily attributed to the regional geology and paleoenvironment background a multiproxy based stratigraphic division is considered very necessary when paleomagnetic and climatic boundaries are defined exactly in a specific area of the southern clp

clay minerals and their paleoenvironmental interpretation in the baoji loess section southern loess plateau china abstract clay minerals from the loess paleosol section at baoji in north central china were studied by x ray diffraction major components calculated by comparing major peak heights were estimated as follows illite 55 75 kaolinite 10 25 mixed layer chlorite vermiculite 10 20 chlorite

comparison of particle size characteristics of the tertiary red clay and pleistocene loess in the chinese loess plateau implications for origin and sources of the red clay the origin of the tertiary red clay underlying the pleistocene loess in the chinese loess plateau remains controversial although several lines of evidence have suggested a wind blown origin this study examines the particle size parameters of the late miocene and pliocene red clay by comparing it with those of the late pleistocene loess the particle size distribution of a total of 15 339 loess and 6394 red clay samples taken from 12 loess sections along a north south transect and two red clay sequences at lingtai and jingchuan was systematically analysed the median grain size skewness and kurtosis of the late pleistocene loess all show a systematic southward change and are principally influenced by distance from source region the spatial and temporal differentiation of dust deposits is expressed in a skewness kurtosis median grain size ternary diagram from which the distance to the source region can be inferred the particle size characteristics of the tertiary red clay sediments are very similar to those of the palaeosols within the late pleistocene loess deposits suggesting an aeolian origin for the red clay based on the comparison of red clay and loess in the ternary diagrams it is inferred that the source sink distance was greater in the neogene than in the last and penultimate interglacials and that the dust source region in north western china underwent a progressive expansion during the period from at least 7ae0 ma to the present

periodicities of palaeoclimatic variations recorded by loess paleosol sequences in china abstract palaeoclimatic periodicity recorded by chinese loess paleosol sequence has been investigated for a number of years however conclusions from previous investigations are still controversial and interpretation of cycle evolution is quite equivocal in this study two typical loess paleosol sequences 148 and 191 m in thickness respectively in the central chinese loess plateau are sampled 3872 samples total and measured for grain size distribution and magnetic susceptibility in order to reconstruct the palaeoclimatic changes over the past three million years on the basis of a new sensitive proxy indicator of palaeoclimate and a newly developed independent time scale not orbitally tuned two time series of asian dust storm variations which are highly related to the palaeoclimate system changes are obtained wavelet and spectrum analyses indicate that there are approximately 400 200 100 66 57 41 31 27 and 22 kyr cycles in these typical loess paleosol records some orbital driven cycles are weak and are not well presented in the new time series while some non orbital cycles are found since the eccentricity frequencies of the solar irradiance of approximately 400 and 100 kyr are preserved in these palaeoclimatic sequences the lack of relatively short time orbital cycles of 41 kyr obliquity and 22 kyr precession cycles in part of the two time series may be explained by the relatively low time resolution of the loess paleosol deposits through an astronomical estimate the obliquity and precession cycles should leave stronger footprints on records of palaeoclimatic variations at the middle latitudes of the northern hemisphere the presence of non orbital cycles may be explained by unstable dust deposition processes and pedogenic processes in the paleosol units which could misrepresent or obliterate the imprint of the solar irradiance frequency this conclusion may indicate that one should be cautious when investigating specific palaeoclimatic changes e g at sub orbital time scales recorded in loess deposits especially in the paleosol units

an 800 ky proxy record of climate from lake sediments of the zoige basin eastern tibetan plateau abstract we present the results of magnetic susceptibility geochemical and pollen analyses of a 120 m long core of lacustrine and fluvial sediments from the zoige basin eastern tibetan plateau palaeomagnetic dating indicates that the sediment sequence spans the last ca 800 ky the magnetic susceptibility record appears to be related to global ice volume over this period and this relationship is used to produce a tentative revised chronology for the sediment sequence the various climate proxies show a pattern of periodic variations over the last 800 ky bp the date of 500 ky bp is a significant boundary prior to this date the climate proxies show a pattern of more frequent variability after 500 ky bp the variations are of lower frequency and higher amplitude the results also indicate that marine oxygen isotope stage 13 was an unusually intense interglacial in the eastern tibetan plateau and chinese loess plateau areas

magnetostratigraphic dating of river terraces rapid and intermittent incision by the yellow river of the northeastern margin of the tibetan plateau during the quaternary up to 23 paleosols have been identified in loess sequences that overlie fluviatile sediments on seven terraces of huang he the yellow river and daxia he in the linxia basin at the northeastern margin of the tibetan plateau the magnetostratigraphic record in the oldest sequence appears to be fairly complete and spans the entire quaternary it includes evidence for the jaramillo and olduvai normal polarity subchrons within the matuyama chron as well as the cobb mountain and stage 54 formerly gilsa events age constraints within the brunhes are provided by 14c and thermoluminescence optical stimulated luminescence dating the magnetostratigraphic chronology of the quaternary sediments indicates that terraces were formed at about 1 66 1 4 1 1 0 6 0 12 0 055 and 0 01 ma the terraces may represent climatically induced pauses in long term tectonically induced incision by the rivers on the basis of terrace heights and ages incision rates were highest from 1 66 to 1 4 ma 1 m kyr decreased from 1 4 to 0 12 ma 0 1 m kyr and increased from 0 12 ma to present 0 75 m kyr if river incision is attributed solely to uplift of the tibetan plateau then this uplift appears to have been rapid as well as intermittent following the first evidence of the existence of huang he in this area at about 1 75 ma however the effects of uplift cannot be fully separated from incision caused by changes in climate copyright 1997 by the american geophysical union

magnetic susceptibility of loess in china abstract the low field susceptibility of the loess deposits in the chinese loess plateau is due to both paramagnetic and ferromagnetic minerals paramagnetism can be seen in the less to unweathered loess horizons where superparamagnetic contributions which arise from ultrafine magnetite particles are not as strongly developed as in the heavily weathered palaeosols frequency dependent susceptibility and minimum unblocking temperatures of low temperature thermoremanent magnetization generally indicate finer grain sizes in the palaeosols as compared to the loess beds this grain size difference and the fact that susceptibilities of the same stratigraphic palaeosol layer vary by an order of magnitude between the western and central regions of the plateau are considered as strong evidence that the ultrafine magnetite is not of detrital aeolian origin but was formedin situ the pedogenetic processes are clearly related to palaeoclimatic changes therefore the various susceptibility properties may serve for a detailed reconstruction of the continental palaeoclimatic conditions for the last 2 5 ma since the palaeomagnetically dated beginning of loess sedimentation in china

astronomical calibration of the matuyama brunhes boundary consequences for magnetic remanence acquisition in marine carbonates and the asian loess sequences we have compiled 19 records from marine carbonate cores in which the matuyama brunhes boundary mbb has been reasonably well constrained within the astronomically forced stratigraphic framework using oxygen isotopes by correlation of the 18o data to a timescale based on astronomical forcing we estimate astronomical ages for each of the mbb horizons in all but one record the mbb occurs within stage 19 most magnetostratigraphic sections in asian loess place the mbb within a loess interval since loess deposition is presumed to be associated with glacial intervals loess horizons should correspond to even numbered oxygen isotope stages a glacial age for the mbb is at odds with the results presented here which firmly place the mbb within interglacial stage 19 inconsistency among the many loess sections and between the loess and the marine records suggests that the magnetic interpretation of loess sections may be more complicated than hitherto supposed the mean of the stage 19 age estimates for the mbb is 777 9 1 8 n 18 inclusion of the single stage 20 age results in a mean of 778 8 2 5 n 19 the astronomical age estimate of the mbb compares favorably with an unweighted mean of 778 2 3 5 n 10 from a compilation of 40ar 39ar results of transitional lava flows combining the two independent data sets yields a grand mean of 778 0 1 7 n 28 the new compilation shows virtually no trend in placement of the mbb within isotope stage 19 as a function of sediment accumulation rate we interpret this to mean that the average depth of remanence acquisition is within a few centimeters of the sediment water interface separating the cores into two geographic regions an indo pacific caribbean ipc group and an atlantic group results in a significant difference in the position of the mid point of the reversal with respect to the astronomical time scale the data presented here suggest a difference of several thousand years between the two regions this observation could be caused by systematic differences between the two regions in sedimentation rate within the interval of interest systematic differences in remanence acquisition or by genuine differences in the timing of the directional changes between the two regions

spatial and temporal patterns of grain size and chemical weathering of the chinese red clay formation and implications for east asian monsoon evolution abstract palaeoclimatic interpretation of the red clay in the chinese loess plateau is particularly important for understanding of the east asian monsoon evolution from pliocene to the quaternary in this study a n s transect involving five loess red clay sections across the loess plateau was selected for detailed investigation with analyses of grain size and major element geochemistry in order to address the spatial pattern results indicate that the red clay contains large amount of coarse 16 m fraction and shows a prominent n s decreasing gradient much similar to that of the overlying loess suggesting that the dust transport was dominantly by low level northerly northwesterly winds compared with overlying loess the red clay is markedly fine and rather constant through all the sections implying a distant and steady dust source area about 200 km further north during most of the pliocene time pedogenic leaching intensities inferred from geochemical data display a clear decreasing trend from south to north both for the red clay and the loess suggesting that the modern spatial pattern of the east asian monsoon regime has been maintained at least for the past 5 ma the n s spatial gradient however might be smaller during the pliocene than the quaternary period temporally two short periods of climatic deterioration implied by marked grain size coarsening and low weathering intensity occurred at 5 3 and 3 5 ma respectively which divide the pliocene into two major stages the 5 3 3 5 ma stage is characterized by a steady state climate through the entire region consistent with other records in the 3 5 2 7 ma stage the red clay in the jingbian section shows a noticeable coarsening in grain size than the previous stage indicating some southward extension of the deserts in agreement with mass accumulation rate record in the north pacific but the eolian dust deposition remained relatively stable in major part of the loess plateau until 2 7 ma the red clay deposition was then terminated by massive and coarse loess deposition in the entire region suggesting dramatic intensification of the winter monsoon in response to the onset of extensive glaciation of northern hemisphere

magnetism of chinese loess deposits summary the age of chinese loess deposits has long been disputed biostratigraphical and earlier magnetostratigraphical investigations placed the entire loess formation within the pleistocene and ascertained a maximum loess age of about 1 2 myr a new collection of nearly 500 samples from a natural outcrop and a borehole section near lochuan lat 35 8 n long 109 2 e shaanxi province has been dated by magnetic stratigraphy thermal cleaning of the natural remanent magnetization nrm removes a strong secondary component of viscous origin along the present geomagnetic field which resides largely in magnetite the characteristic nrm component is due to haematite which is thought to be of chemical origin rhythmical intensity variations of nrm and initial susceptibility depend on the loess lithology and may reflect climatic changes during loess deposition the palaeomagnetic results are consistent between the two sections and yield a clearly defined magnetic polarity zonation the brunhes matuyama boundary and the jaramillo subchron have been positively identified in both outcrops at exactly the same stratigraphic level the olduvai subchron has been found in the borehole section which records the entire loess sequence most probably the formation of chinese loess began shortly after the matuyama gauss polarity transition therefore a late pliocene age of about 2 4 myr is assigned to the oldest loess sediments measured

methane concentration profiles in a lake with a permanently anoxic hypolimnion lake lugano switzerland italy methane concentrations were measured in the water column of the northern basin of lake lugano in 1993 and 1994 methane profiles show three distinct zones 1 low concentrations generally below 0 1 mmol m 3 from the surface to 80 90 m depth 2 a sharp rise in concentration up to 50 mmol m 3 from 80 90 to not vert similar 150 m depth and 3 from not vert similar 150 m depth to the bottom with a lower concentration gradient and with the highest methane concentrations in near bottom water was not vert similar 80 mmol m 3 these profiles result from a combination of several factors such as fluxes from sediments spatially variable vertical mixing and aerobic and anaerobic bacterial oxidation in the water column 13c values indicate a biogenic origin for the methane the methane inventory in the anoxic hypolimnion is not vert similar 2000 metric tonnes yet its transfer to the surface water is almost completely cancelled by oxidation at the permanent redox interface situated at not vert similar 90 m water depth increased methane concentrations in near surface water are not related to the deep water methane reservoir but probably result from bacterial production of methane in the photic zone surface water is over saturated with methane in respect to the atmosphere anthropogenic eutrophication in temperate zone lakes has affected the carbon budget and methane production and storage the potential impact of these changes on global emissions to the atmosphere should be evaluated

a lock in model for the complex matuyama brunhes boundary record of the loess palaeosol sequence at lingtai central chinese loess plateau summary in most marine sedimentary records the matuyama brunhes boundary mbb has been found in interglacial oxygen isotope stage 19 in the magnetostratigraphic records of most chinese loess palaeosol profiles the mbb is located in loess layer l8 which was deposited during a glacial period the mbb at lingtai central chinese loess plateau also occurs in l8 and is characterized by multiple polarity flips the natural remanent magnetization is mainly carried by two coexisting components the higher coercivity harder component dominates in loess layers and is thought to be of detrital origin the lower coercivity softer component prevails in palaeosols and was most probably formed in situ by bio chemical processes a lock in model for the lingtai mbb record has been developed by extending the lithologically controlled pdrm model of bleil von dobeneck 1999 it assumes two lock in zones the nrm of the magnetically harder component is physically locked by consolidation shortly after loess deposition whereas the softer component is formed at greater depth by pedogenesis and acquires a chemical remanent magnetization of younger age at polarity boundaries grains carrying reversed and normal directions may therefore occur together within a single horizon the model uses arm coercivity spectra to estimate the relative contributions of the two components it is able to explain the observed rapid multiple polarity flips and low magnetization intensities as well as the stratigraphic shift of the lingtai mbb with respect to the marine records

rescaled range analysis of paleoclimatic proxies two geophysical measurements have been widely used as paleoclimatic indicators oxygen isotope ratios from deep sea cores and magnetic susceptibility of loess sediments both types of record have been shown to possess climatic information as they share the same dominant frequencies of the earth s orbital movements which according to milankovitch s theory drive the climatic system but these two physical quantities may respond to climatic variations in different ways consequently they may possess different long term characteristics which can be detected by the technique of rescaled range r s analysis here we report results from four sets of data two oxygen isotope records and two loess susceptibility profiles analysis indicates that hurst exponents of about 0 8 are typical for deep sea oxygen data whereas values of about 0 9 characterize loess susceptibility sequences if mandelbrot s explanation is taken these distinct values imply that the loess data are more self correlated and possess str

authigenic 10be 9be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the brunhes matuyama boundary geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium 10 10 be production rates authigenic 10 be 9 be ratios proxy of atmospheric 10 be production from oceanic cores therefore complete the classical information derived from relative paleointensity rpi records this study presents new authigenic 10 be 9 be ratio results obtained from cores md05 2920 and md05 2930 collected in the west equatorial pacific ocean be ratios from cores md05 2920 md05 2930 and md90 0961 have been stacked and averaged variations of the authigenic 10 be 9 be ratio are analyzed and compared with the geomagnetic dipole low series reported from global rpi stacks the largest 10 be overproduction episodes are related to dipole field collapses below a threshold of 2 10 22 am 2 associated with the brunhes matuyama reversal the laschamp 41 ka excursion and the iceland basin event 190 ka other significant 10 be production peaks are correlated to geomagnetic excursions reported in literature the record was then calibrated by using absolute dipole moment values drawn from the geomagia and pint paleointensity value databases the 10 be derived geomagnetic dipole moment record independent from sedimentary paleomagnetic data covers the brunhes matuyama transition and the whole brunhes chron it provides new and complementary data on the amplitude and timing of millennial scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities

misleading positions of geomagnetic reversal boundaries in eurasian loess and implications for correlation between continental and marine sedimentary sequences abstract the matuyama brunhes boundary mbb where the earth s magnetic field changed to its present orientation is one of the most frequently used time markers in continental quaternary stratigraphy although magnetic signals have been successfully recovered from loess deposits and an apparently coherent magnetostratigraphy seems to be in place a close examination of the published loess records from northern mid latitudes reveals significant uncertainty and variability for the position of the mbb in asia and part of central europe the mbb has been found in loess a glacial deposit this is in contrast to the well established palaeomagnetic records in deep sea sediments where the mbb is located in the interglacial oxygen isotope stage 19 this discrepancy has caused serious confusion in stratigraphic correlation between loess and marine sequences here we examine the causes of the discrepancy between the two sedimentary environments in their records of the mbb our approach includes a comparison of the mbb in loess and other continental records and an evaluation of the stratigraphic significance of the microtektites found around the mbb based on the occurrence of the mbb in an interglacial stage in lake and continental margin sequences and the correlative stratigraphic positions of the microtektites in marine sediments and loess we demonstrate that the measured positions of the mbb in loess are erroneous and misleading and its true occurrence was during the time of formation of the palaeosol corresponding to oxygen isotope stage 19 the most plausible cause for the apparent offset i e the mbb being found in the underlying loess instead is that the acquisition of remanent magnetisation in loess occurs at a certain depth substantially below the land surface the degree of such displacement is dependent on the lithology and structure of the deposits formed prior to the reversal and the time delay is estimated to be in the order of 103 104 years we show that other geomagnetic boundaries such as those of jaramillo and cobb mountain in loess have been similarly displaced though to a varying extent we suggest that the remanence acquisition in loess is closely related to the post depositional evolution in the structure of loessic materials which is in part influenced by regional climate conditions our conclusions on the displaced remanence acquisition have implications for loess chronology magnetostratigraphy as well as the geomagnetic interpretation of detailed magnetic signatures from loess

magnetostratigraphy and palaeoclimatic significance of late tertiary aeolian sequences in the chinese loess plateau summary the aeolian red clay sequence in the central part of the chinese loess plateau was investigated in an attempt to obtain magnetostratigraphic and palaeoclimatic records from the results we deduce that aeolian dust accumulation and the related east asia palaeomonsoon system began at least 7 6 myr ago and that the tibetan plateau had reached a significant elevation by that time the late tertiary palaeoclimatic history of the red clay as reflected by magnetic susceptibility is reconstructed for the time period 7 6 2 5 ma increases in aeolian dust accumulation for the last 7 6 myr appear to have a close relation with the uplift processes of the tibetan plateau the remarkable increase of aeolian dust accumulation beginning at 3 2 ma appears to reflect the influence of an increasing global ice volume on the east asian monsoon and aeolian dust accumulation

astronomical timescale and palaeoclimatic implication of stacked 3 6 myr monsoon records from the chinese loess plateau abstract magnetic susceptibility and grain size records from two continuous red clay and loess palaeosol sequences on the chinese loess plateau have been generated to investigate the evolution and variability of the east asian monsoon eam during the late pliocene and pleistocene tuning the grain size records to orbital obliquity and precession yields an improved astronomical timescale for the loess palaeosol sequence 0 2 6 ma and an extended age model for the upper red clay formation 2 6 3 6 ma this timescale indicates older ages for a number of the magnetic polarity boundaries consistent with lock in depth offsets in loess sequences good site to site correlation enables generation of stacked grain size and susceptibility records spanning the last 3 6 myr these records indicate that monsoon evolution since the late pliocene can be subdivided into three phases 0 1 25 1 25 2 72 and 2 72 3 4 ma each phase is characterized by unique amplitude and frequency characteristics for both summer monsoon magnetic susceptibility and winter monsoon grain size spectral analyses of the stacked monsoon proxies indicate that characteristics of both the summer and winter monsoons are dominated mainly by variance in the eccentricity 410 and 100 kyr obliquity 41 kyr and precession 23 and 19 kyr bands over the past 3 4 myr implying a non linear response of the long term eam evolution to orbital and glacial forcing

iodine in groundwater of the guanzhong basin china sources and hydrogeochemical controls on its distribution groundwater sampling at 179 sites in the guanzhong basin china indicated iodine concentrations ranging from 2 to 28 620 g l 7 3 of the sites have iodine concentrations 300 g l and are defined as iodine excess water sites with low groundwater iodine concentrations are mainly distributed at the edge of a piedmont alluvial proluvial fan containing bicarbonate rich water with a low mineral content near neutral ph values and low fluorine concentrations the piedmont fan is characterized by a fast groundwater flow and active leaching of iodine from the sediments conversely high groundwater iodine concentrations are principally located in silty or clayey sedimentary zones having low groundwater flow rates weakly alkaline to alkaline ph values and water containing hco3 so4 so4 cl and cl so4 hydrochemical types elevated iodine concentrations in shallow groundwater commonly occur in discharge areas where there is a high rate of solute evaporation elevated iodine concentrations in deep groundwater are likely attributed to microbial decomposition of organic matter under anaerobic conditions processes of iodine enrichment lead to correlations between high iodine and high fluorine contents in shallow groundwater and between high iodine and high arsenic concentrations in deep groundwater moreover redox processes and active water recycling are important factors for groundwater iodine enrichment

variability of east asian winter monsoon in quaternary climatic extremes in north china in order to examine high frequency variations of east asian winter monsoon in quaternary climatic extremes two typical loess paleosol sequences in the chinese loess plateau were investigated sandy layers in the loess deposits the upper sand and lower sand layers l9 and l15 respectively which represent a high resolution record of paleomonsoon changes have been sampled at intervals of 5 6 cm from sections at luochuan and xifeng the grain size and magnetic susceptibility was measured for all samples the grain size results a proxy of winter monsoon strength indicate that the winter monsoon strength fluctuated on a millennial timescale during cold climatic extremes with climatic events of a few hundred to a few thousand years however the winter monsoon was relatively stable during warm periods the magnetic susceptibility signal a proxy of summer monsoon intensity is practically constant over the same period this is tentatively explained by the assumption that the summer monsoon intensity was too low to be recorded in the magnetic susceptibility signal the intensified winter monsoon events show periodicities in a range of 1000 to 2770 yr with a dominant cycle of approximately 1450 yr the detection of this oscillation in older glacial stages strongly suggests that it may be a pervasive cycle of the cold climatic phases of the quaternary millennial scale variations of the winter monsoon may be caused by instability of the westerly jet which is determined by temperature differences between the polar and the equatorial regions

climatic implications of loess deposits from the beijing region variations in magnetostratigraphy pedostratigraphy grain size and magnetic suscep tibility of the loess deposits near beijing have been studied at two sections the sections are about 400 km east of the main loess deposits in china have a maximum thickness of 100 m and extend back to 1 1 ma the sequence consists of 14 loess palaeosol couplets s0 s14 which correlate well with sequences in the loess plateau susceptibility records from the sites near beijing are comparable to the xifeng luochuan and baoji sections located in the middle part of the loess plateau however the down core variations in the grain size in the upper lishi formation exhibit some differences the median grain size increases by about 25 30 m from l4 to l2 with the sandy grains 63 m increasing from 10 20 wt to 40 50 wt this implies that the depositional environment of the dust sources in the beijing loess section is different in some aspects from the loess plateau the beijing loess may have had a different dust source than the loess plateau copyright 2001 john wiley sons ltd journal of quaternary science

a link between geomagnetic reversals and events and glaciations abstract the apparent duration of geomagnetic polarity events in arctic ocean sediments is much longer than in sediments from lower latitudes in fact while the remanence of brunhes age sediment cores from the yermak plateau at 82 n is fully reversed for 30 of their lengths 1 the events often evade detection in many other continuously deposited sediments for example the laschamp event is absent in an otherwise high resolution record of secular variation from lac du bouchet 2 which is located near the laschamp volcanics where the event was first detected very short event durations of a few hundred years at the most have been suggested before 2 3 because sedimentation rates in the arctic ocean were increased during glaciations the exaggerated proportion of reverse polarities in sediments from high latitudes suggests a link between glaciation and field reversals this suggestion is supported by magnetostratigraphic results obtained from thick loess paleosol sequences in china 4 these demonstrate that all polarity boundaries separating chrons and subchrons since the gauss matuyama field reversal have been recorded in loess and thus during periods of cold climate although conflicting evidence exists for some boundaries furthermore the ages of 22 events and chron boundaries have been compared with the oxygen isotope record 5 thought to represent global ice volume all events and reversals younger than 2 6 ma may have occurred during periods of global cooling or during cold stages however some ages are still too poorly dated for a definite correlation climatic signals also exist in the two longest relative paleointensity records 6 7 but these are suspected to be caused by climatically driven variations in the rock magnetic parameters a mechanism for field reversals may be the acceleration of the earth s rotation caused by lowering of the sea level during glaciations the short duration of events also implies that the geomagnetic field can reverse an order of magnitude faster than commonly assumed

580 000 year environmental reconstruction from aeolian deposits at the mu us desert margin china abstract a 76 7 m thick section of aeolian sediment is exposed in the transition zone between the mu us desert and the loess plateau of northern china the aeolian sediments contain sand beds loess layers and palaeosols the particle size distribution data and the sem examination of quartz grains suggest the sand beds are wind blown origin palaeomagnetic measuring combined with thermoluminescence tl dating and pedostratigraphic correlation suggests the studied aeolian sequences were deposited within about 580 kyr the sand layers appear to reflect the episodic extensions of mu us desert during phases of active dune formation and intensified winter monsoon both the stratigraphy and the proxy climatic curves such as bulk magnetic susceptibility and grain size indicate that large amplitude second order climatic oscillations occur during both glacial and interglacial periods it is worth noting that nearly all the interglacial soils can be sub divided by the intercalated sand or loess beds this second order climatic oscillations are on the order of 10 000 of years which may reflect the precession scale variations of southeast summer monsoon driven by the orbital pacing of insolation in low latitudes

magnetic mineralogy of chinese loess and its significance summary the topmost 16 metres of the loess section at xifeng central chinese loess plateau which cover the last 128000 years consist of two palaeosol beds interlayered by a loess horizon hysteresis parameters frequency dependent field and temperaturedependent susceptibility show very similar and stable magnetic mineral constituents in both loess and palaeosol samples the concentration and grain size of magnetite maghaemite and haematite control the magnetic properties of chinese loess susceptibility and loess thickness are closely related to geographic position and present climate across the loess plateau the loess and palaeosol magnetic properties are largely controlled by the fine grained magnetite formed in various quantities and grain sizes under the influence of pedogenesis during variable palaeoclimatic conditions therefore regional and global palaeoclimatic development during the last 2 5 myr can be reconstructed from susceptibility records in the loess plateau

paleomagnetism of ar ar dated lava flows from the ceboruco san pedro volcanic field western mexico evidence for the matuyama brunhes transition precursor and a fully reversed geomagnetic event in the brunhes chron 1 we report a detailed paleomagnetic and rock magnetic study of 17 independent lava flows belonging to the trans mexican volcanic belt 175 oriented samples were collected in the ceboruco san pedro volcanic field these sites were previously dated by means of a state of the art 40ar 39ar geochronological method and span from 819 to 2 ka rock magnetic experiments which included continuous susceptibility and hysteresis measurements point to simple magnetic mineralogy in most cases the remanence is carried by ti poor titanomagnetite of pseudosingle domain magnetic structure fourteen flows give normal magnetic polarities while two are reversely magnetized only one cooling unit yields intermediate paleodirections the paleodirections of the flow dated at 819 25 ka correspond to a vgp latitude of 18 n this anomalous field behavior apparently recorded prior to the matuyama brunhes m b reversal may coincide with the transitionally magnetized lavas on la palma canary islands 40ar 39ar age of 822 2 8 7 ka and with an event featured in several marine sediment records thus this geomagnetic event defined as m b precursor is probably global in extent two independent lava flows dated at 623 91 and 614 16 ka yield reverse paleodirections age uncertainties make it difficult to claim the discovery of a new geomagnetic event it is possible that these lavas erupted during the worldwide observable big lost event 40ar 39ar age of 580 2 7 8 ka which has probably been longer and more complex than it is generally believed for geomagnetic excursions

inconsistent palaeomagnetic recording of the blake event in chinese loess related to sedimentary environment three loess sequences located east of the liupan mountain region china were studied to obtain records of the blake polarity event palaeomagnetic records from the appropriate stratigraphic interval of these three sequences however record the blake event poorly in one case and not at all in the other two cases it is important to understand why these loess sequences miss the blake event whereas others record it quite well we conclude that regional variations in the sedimentary environment over the chinese loess plateau are responsible for the inconsistent recording of the blake event the palaeomagnetic records suggest a threefold subdivision of the chinese loess plateau into 1 the central and southern portions of the part of the plateau that lies east of the liupan mountains where the primary record of the blake event has been severely smoothed or wiped out by pedogenic processes during palaeosol s1 formation 2 the northern margin of the loess plateau to the east of the liupan mountains where frequent severe dust storms have resulted in discontinuous records with a high probability of missing the blake event and 3 the region west of the liupan mountains where loess sequences are deposited rapidly and nearly continuously with only minor pedogenesis and are thus capable of recording short events like the blake

two geomagnetic excursions during the brunhes chron recorded in chinese loess palaeosol sediments summary detailed palaeomagnetic integrated with rock magnetic studies have been carried out on a loess palaeosol sequence in baoji shaanxi province southern chinese loess plateau for most samples stepwise thermal demagnetization revealed two well defined magnetization components a low temperature component ltc which was isolated between 100 and 200 c is consistent with the present geomagnetic field direction a high temperature component htc which was isolated between 250 and 620 680 c shows normal reversed or transitional polarities our new magnetostatigraphy revealed two distinct geomagnetic excursions recorded in loess unit of l5 and palaeosol unit of s7 respectively and the matuyama brunhes m b polarity boundary in loess unit of l8 rock magnetic experiments demonstrated that the specimens from the excursion zones have the same magnetic properties as those from the brunhes normal or matuyama reversed polarity zones measurements of anisotropy of magnetic susceptibility ams showed that the sediments have primary sedimentary fabrics based on the palaeoclimatological and magnetostratigraphic age models the middle brunhes excursion in loess l5 is dated at 413 433 ka and the early brunhes excursion is estimated to occur 23 33 ka after the m b reversal comparing with previously reported geomagnetic excursions in the brunhes chron the middle brunhes excursion l5 is likely global for the early brunhes excursion s7 we need further studies to examine its global occurrence

determining paleosol topography using seismic refraction abstract the seismic refraction reversed profiling technique has been used to investigate the topography of the last interglacial soil paleosol s1 within the central chinese loess plateau near xifeng the results suggest an essentially flat lying soil at a depth which varies by only a few meters over an area of more than 10 km2 in addition the results indicate a high velocity layer at 50 60 m depth which is thought to coincide with a layer of carbonate concretions at the base of paleosol s5 the results agree well with the local loess paleosol stratigraphy for this area and indicate that the seismic refraction method is a rapid technique for investigating paleotopography

a long term increasing aridification and cooling trend at the chinese loess plateau during the pliocene the development of asian aridification and cooling is a research hotspot nowadays loess red clay sequence in the chinese loss plateau provides an excellent terrestrial archive of such paleoclimatic evolution this paper applied the magnetic unmixing technique to isolate the magnetic components of the red clay sequence for the first time the jiaxian section in the north edge of chinese loess plateau is sensitive to paleoclimate changes because it is in the transitional zone of the monsoon and non monsoon area systematic magnetic measurements and xrd analysis consistently indicate that the magnetic components of red clay are predominantly magnetite maghemite and hematite the strongly developed paleosols exhibit high content of soft magnetic minerals higher ms and mrs and lower bc and bcr while the weakly developed paleosols and loess samples display the opposite features with increasing alternating field the contributions of soft components to sirmx mt are cleaned gradually sirm is the saturation isothermal remanent magnetization sirmx mt represents the residual sirm after alternating field demagnetization at x mt the significant contributor to sirm100 mt is hematite an indication of the intensity of chemical weathering variations in the ratios of sirm100 mt sirm sirm100 mt sirm60 mt and sirm100 mt sirm30 mt document a long term up section decreasing trend during the last 5 2 6 ma with similar trends to the long term up section increase in 18o values of marine records decreased hematite content indicates weakened chemical weathering which further implies an increasing aridification and cooling and a gradually weakened summer paleomonsoon mainly in the depositional area chinese loess plateau in some loess layers where hematite is mainly of aeolian origin the mineral magnetic signals may indicate aridification and cooling in the asian interior source region this long term aridification and cooling trend is probably attributed to the comprehensive activity of ongoing global cooling progressive uplift of the tibetan plateau and changes in land sea distribution

seismic stratigraphy of chinese loess abstract a loess section near lanzhou china has been investigated using the seismic refraction technique the results show that the method is able to discriminate four distinct seismic boundaries within the section as well as indicating that the loess bedrock contact occurs at a depth of more than 200 m a 30 m deep pit was subsequently dug and revealed that the first two seismic boundaries correspond to soil units sa an intermediate soil within loess unit l1 and s1 the last interglacial soil at the base of l1 these results though preliminary indicate the potential of the technique not only for mapping loess bedrock contacts but also for determining the finer subsurface detail of the loess palaeosol stratigraphy

the jaramillo subchron a geochronological marker horizon in the palaeoanthropological record of china abstract the jaramillo subchron is routinely recognised in chinese loess palaeosol sequences as well as in fluvial lacustrine sequences such as those in the nihewan basin north china many of these sections extend back to and below the olduvai subchron and several especially in the nihewan basin contain palaeolithic sites initially the jaramillo subchron was used to determine whether a palaeolithic site or hominin specimen lay above or below it and it played an important role in demonstrating that the chinese hominin and palaeolithic record extended past 1 ma its main application now is as a marker horizon in sections that also contain the olduvai subchron estimation of the age of palaeolithic material between these two marker horizons at nihewan and elsewhere was initially based on estimates of average sedimentation rate between these two points the dating of majuangou iii to 1 66 ma is one example and provides the current earliest date for hominins in north china however age estimates have become more sophisticated by estimating the timing and during of fluvial lacustrine cycles and by attempts to link these to the marine isotope record although this has resulted in sites such as xiaochangliang now having a variety of possible ages the precise age and climatic context of early pleistocene sites in such settings should become clearer overall these studies involving the jaramillo subchron have been more successful in estimating the first arrival of hominins in north china than in southern china where the first appearance of hominins remains unclear

properties of magnetic mineralogy of alaskan loess evidence for pedogenesis abstract the in situ pedogenic enhancement of ferrimagnetic content provides the well established patterns of magnetic susceptibility variation within mid to low latitude loess deposits such as those of china and central europe however this pattern of high magnetic susceptibility in palaeosols and lower values in unweathered loess is not replicated in the higher latitude loess deposits of alaska and siberia in these localities the relationship is inverted with high values in loess and low values in palaeosols this inverse relationship has been explained by the idea that magnetic susceptibility is reflecting the magnitude of an aeolian ferrimagnetic component of consistent mineralogy the grain size of which is related to average wind velocity however the results of the magnetic study presented in this paper suggest that there are differences in magnetic properties between alaskan loess and palaeosols not only in magnetic grain size and concentration but also in magnetic mineralogy this complicates the simple hypothesis of a wind velocity signal by introducing an additional factor into the climatic signal in contrast to the enhancement of susceptibility observed in palaeosols of the loess plateau china we suggest that the low magnetic susceptibility values in the alaskan palaeosol units are a reflection at least in part of the alteration of the ferrimagnetic content by post depositional processes associated with waterlogging i e gleying of the soils

the history and variability of the east asian paleomonsoon climate abstract changes in the east asian paleomonsoon reflect interactions between the global atmosphere ocean land and ice systems and are also an expression of their combined effect within the boundary conditions imposed by the east asian continent and solar radiation the history of the east asian monsoon is an alternation between dominance by the dry cold winter and warm humid summer monsoons high resolution eolian sequences preserved in the chinese loess plateau reveal that the east asian monsoon may have commenced at least 7 2 ma ago they also provide evidence indicating that the pulsed uplift of the tibetan plateau at about 3 4 and 7 2 ma may have played an important role in inducing climate change the palaeoclimatic records of the last glacial cycle show high frequency variability on time scales of 1000 year or even shorter and instability of the east asian paleomonsoon system the high frequency variability could be due to a non linear response to orbital forcing or a result of the coupling processes between different components of the global system cold air activity in northern high latitudes the trans equatorial air streams from the southern hemisphere and possibly enso may have played an important role in east asian monsoon variability the synchroneity of all the palaeoclimatic events along the polar equator polar pep transect is still an open question correlation of limited palaeoclimatic records for the last 30 kyr obtained from east asia and australia suggests that the trans equatorial air streams driven by the monsoon and trade winds may have had an influence on opposite hemispheres

new insights into magnetic enhancement mechanism in chinese paleosols article i nfo magneticsusceptibilityof chineseloess paleosolsequenceshasbeenextensivelyusedasareliablepaleoclimatic proxy for reconstruction of the asian summer monsoon system and its enhancement is usually attributed to neoformation of fine grained ferrimagnetic particles via pedogenesis but there is little understanding of either the formation process of such magnetic particles or their actual form and grain sizes to investigate these problems scanning electron microscope observations were conducted on magnetic extracts from pristine loess and strongly pedogenicpaleosol samples from xifeng onthe chineseloess plateau both magneticextracts commonly contained coarse grained detrital magnetite with grain size ranging from a few mt o several tens of m however the magnetic extract from the mature paleosol sample additionally included coarse silicate parti cles with ultrafine ferrimagnetic inclusions while that from the pristine loess sample did not the size of the ferrimagnetic inclusions mainly ranged from tens to hundreds of nanometers the temperature dependent susceptibility and hysteresis loops of the paleosol sample combined with the stratigraphic variations of rock magnetic parameters showed that the pedogenic maghemite inclusions should be a potential contributor to magnetic enhancements in chinese paleosols the fine grained ferrimagnetic inclusions have been pedogenically formed by weathering of coarse grained fe bearing silicate minerals our proposed magnetic enhancement mechanism is consistent with the accepted rock magnetic result that magnetic enhancement in chinese paleosols is caused by pedogenic maghemite grains in superparamagnetic and single domain size regions the presence of ultrafine ferrimagnetic grains as inclusions within coarse silicate particles is also consis tent with han and jiang s 1999 significant experimental result that magnetic enhancement in chinese paleosols is mainly contributed by the 0 5 m sediment fractions

aeolian origin of the red earth in southeast china a clay like deposit known as red earth is widely distributed over the terraces and high lands of the yangtze river valley in southeast china its typical pedo stratigraphical features have attracted the interest of pedologists and geologists for many years although its origin is still debated here we report an analyses of the grain size distributions rare earth element bee patterns and upper continental crust ucc normalised major elemental composition of the red earth and compare them with those of the loess and other aeolian deposits in northern china the results show that the red earth in southeast china has two or three end member grain size distributions similar to the sedimentary characteristics and geochemical composition of aeolian deposits found in northern china together with other evidence from field observations these results suggest that the red earth is probably of acolian origin on the basis of these data we suggest that thick aeolian dusts were also deposited in the wet subtropics and that the effect of the winter monsoonal winds upon the dust transport in eastern china was more important than previously believed copyright c 2002 john wiley sons ltd

new chronology of the best developed loess paleosol sequence of hungary capturing the past 1 1 ma implications for correlation and proposed pan eurasian stratigraphic schemes abstract in this paper we are presenting a revised chronology of the best developed longest 100 m lps in hungary dating back 1 1 ma borehole udvari 2a it is based on a non tuned age depth model built on the position of the matuyama brunhes boundary jaramillo and olduvai subchrons furthermore on the assignment of formerly recorded uninterpreted geomagnetic reversals in both chrons other chronometric tools ams 14c dating biostratigraphy tephrostratigraphy yielding absolute ages and or ensuring validation of these were also used records of a middle pleistocene gastropod index fossil neostyriaca corynodes 400 140 ka facilitated verification of ages between mis 10 and mis 6 multiple age control points at 15 25 27 45 120 191 362 430 670 780 900 990 1070 ka were established for the last ca 1 1 ma the resulting chronology is the best resolved independent one so far among danubian basin lpss in light of our data the s3 s4 units were fused as s3 in all serbian and some romanian sites and re correlated with mis 9 the results also point to a misassignment of the s5 units at these sites to mis 13 15 leading to erroneous conclusions regarding paleoclimatic conditions and cyclicity in our new stratigraphic scheme these s5 paleosols were taken to represent the s4 paleosol and recorrelated with mis 11 finally an ideal stratigraphic column dating back 1 1 ma for sw hungary was constructed and correlated with the chinese loess paleosol sequence of xifeng and the benthic oxygen isotope record down to mis 31

magnetic susceptibility of the chinese loess palaeosol sequence environmental change and pedogenesis pronounced differences in concentration alignment and grain size distribution of the magnetic minerals have been identified between loess and palaeosol samples from the section at xifeng central chinese loess plateau superparamagnetic magnetite formed in situ plays an important role in controlling magnetic low field susceptibility the variable brown red colouration of the loess palaeosol sequence is due to a significant hematite component produced by pedogenesis the magnetic fabric of the palaeosols is weaker than that of the loesses this is taken as evidence that the formation of ultrafine ferromagnetic minerals by pedogenesis is the most likely explanation for the observed susceptibility enhancement in palaeosols 4 to 10 times higher than in loesses it is argued that variations of frequency dependent susceptibility are sensitive recorders of second order palaeoclimatic variations during glacial periods whereas bulk susceptibility seems to be an appropriate measure of palaeoclimate change during interglacial periods

nanosized authigenic magnetite and hematite particles in mature paleosol phyllosilicates new evidence for a magnetic enhancement mechanism in loess sequences of china

evidence for a new geomagnetic reversal from lava flows in idaho discussion of short polarity reversals in the brunhes and late matuyama polarity chrons k ar ages and paleomagnetic data for basalt samples from a new core hole site e at the idaho national engineering laboratory inel indicate that the age of the reversed polarity event recorded in snake river plain lavas is older than 465 50 ka 1000 years before present reported previously by champion et al 1981 nine basalt flows eight with normal polarity and one with reversed polarity were recognized in the site e core hole the flows above and below the reversed flow have ages of 491 80 ka and 580 93 ka respectively the inclination of the paleomagnetic field direction of the reversed flow at site e agrees with the inclination of reversed flows elsewhere at inel which have an age of 565 14 ka these reversed flows were previously thought to be correlative with the emperor event we suggest that this polarity event is an older event which we name the big lost reversed polarity subchronozone and subchron a review of data documenting short reversal records from volcanic and sedimentary rocks shows that there is evidence for eight polarity subchrons in the brunhes and two besides the jaramillo in the late matuyama these 10 short subchrons begin to indicate the many short events that cox 1968 hypothesized must exist if polarity interval lengths have a poisson distribution these events are true subchrons not excursions and may or may not have low associated paleointensities although low field strengths might explain why the reversal process aborts the mean sustained polarity interval length since late matuyama chron time is 90 000 years the similarity of this number with the 105 year period of the earth s orbital eccentricity suggests anew that linkage between geomagnetic paleoclimatic and possible underlying earth orbital parameters should be evaluated

the sr and nd isotopic variations of the chinese loess plateau during the past 7 ma implications for the east asian winter monsoon and source areas of loess abstract 143 nd 144 nd and 87 sr 86 sr ratios of the acid insoluble residues of the red clay and overlying loess paleosols from the lingtai profile of the loess plateau china were investigated the results show that variations of the 87 sr 86 sr ratios of the lingtai profile can be divided into two stages from 7 ma b p to 2 5 ma b p the acid insoluble residues in the red clay rc formation are characterized by higher 87 sr 86 sr ratios with an average of 0 7230 from 2 5 ma b p to the present the acid insoluble residues in the wuchen loess wl4 ws1 lishi loess l15 s1 malan loess l1 and holocene loess s0 have relatively lower 87 sr 86 sr ratios and display an overall descending trend from 0 7223 at 2 5 ma b p to 0 7182 at the present among three possible interpretations for the variations of 87 sr 86 sr ratios of acid insoluble residues of the loess provenance change chemical weathering change or grain size distribution change only grain size distribution change provides a satisfactory interpretation this implies that the east asian winter monsoon strength was weak and relatively stable from 7 ma b p to 2 5 ma b p but became continuously enhanced from 2 5 ma b p to the present all the red clay and the overlying loess paleosols in the lingtai profile have generally identical e nd 0 implying that the source regions of these eolian deposits of the chinese loess plateau may be relatively stable and has not changed since 7 ma b p

latest olduvai short lived reversal episodes recorded in chinese loess 1 a duplicate high resolution magnetic record was obtained from two parallel loess sections separated by about 300 m near baoji city southern chinese loess plateau this reveals at least eight short lived reversed polarity episodes in the uppermost part of the olduvai normal polarity subchronozone rock magnetic experiments and anisotropy of low field magnetic susceptibility confirm that the multiple occurrence of short lived reversals is not due to rock magnetic and or sedimentary causes assuming a constant accumulation rate within the olduvai subchron the short episode zone was estimated to span about 24 30 ka and 24 31 ka for the two sections respectively the duration of each short episode ranges from about 0 3 ka to 2 1 ka the present results together with previous worldwide observations show that the occurrence of numerous short reversals is peculiar to the latest olduvai subchron the geodynamo may have been in an anomalous state at that time

asynchronous records of brunhes matuyama reversal in marine sediments and chinese loess review and discussion abstract geomagnetic polarity reversals are generally considered to occur synchronously around the world and are commonly used as time markers to correlate events between different sediment archives they also play an indispensable role for understanding the mechanisms which generate the earth s geomagnetic field nevertheless in the case of the most recent reversal the brunhes matuyama b m reversal 780 ka comparison of paleomagnetic studies in chinese loess paleosol sequences versus marine cores reveal a marked discrepancy in timing of this event this timing offset has led to uncertainties in correlating the chinese loess paleosol sequences with other global climate records this paper briefly reviews the history of study on the b m reversal both in marine and chinese loess sediments and reviews several contentious explanations of the aforementioned b m boundary offset finally the most recent progress of paleogeomagnetic field variation studies using cosmogenic 10 be in chinese loess is introduced with the purpose of suggesting a potential way to address this b m boundary timing offset issue

paleoclimatic context of geomagnetic dipole lows and excursions in the brunhes clue for an orbital influence on the geodynamo the hypothesis of an influence of the astronomical precession on the geodynamo energy budget was recently reappraised by theoreticians paleomagnetic indications of such an influence remain controversial because reconstructions of paleointensity variations from sediments are suspected to be contaminated by lithological paleoclimatically induced influences three sets of complementary indicators are however available 1 records of the direction of magnetization in sediments 2 records of magnetic anomalies of the deep sea floor basalts and 3 records of production variations of cosmogenic isotopes from sediment and ice cores these records confirm the genuine geomagnetic origin of paleointensity lows and their narrow link with excursions or short reversals recorded in various materials and often dated by radiometric methods the analysis of these time series and their comparison with 18o records of the paleoclimate suggest that such globally recorded geomagnetic dipole lows have preferentially occurred in the context of interglacial or transitional paleoclimates at the time of low or decreasing obliquity the dominant periods extracted with the complex continuous wavelet transform technique range from 40 to 125 ka further suggesting a link with orbital parameters these results encourage future efforts of research to improve the precision the resolution and the dating of the time series of geomagnetic dipole low in order to better decipher orbital signatures and understand their origin an important implication of this topic is that the next geomagnetic dipole low should be related with the present interglacial

origin of the miocene pliocene red earth formation at xifeng in northern china and implications for paleoenvironments abstract in the eastern loess plateau region of northern china the quaternary loess soil sequences of the last 2 6 ma are underlain by the hipparion red earth formation magneto stratigraphic studies suggest that it is a near continuous terrestrial record for the period from 7 to 2 6 ma bp and therefore has great potential for the study of asian paleoclimates the origin of this formation is controversial and needs further study in this work the xifeng red earth section a type section for the eastern loess plateau region was studied using optical microscopic analysis grain size measurements and both major and trace element geochemical properties to address questions of its origin and environmental implications the results show that this formation consists of three parts the lower part 6 2 ma bp is a water reworked deposit related to alluvial and slope processes the middle part from 6 2 to 3 6 ma bp was derived from in situ eolian dust deposition but was significantly affected by groundwater oscillations and the upper part from 3 6 to 2 6 ma bp is an eolian formation similar to the quaternary loess soil sequence the grain size of the upper part is significantly coarser than for the middle part but finer than for the overlying loess because the eolian dust deposits in the middle reaches of the yellow river were mainly transported from the deserts in northern china by the northwesterly winter monsoon wind and the westerlies we interpret the eolian origin of the middle and upper red earth formation beginning approximately at 6 2 ma bp as an indication of the strengthening of the aridification of the asian continent desert lands in central asia must have been formed at or by that time to provide a significant source of dust however the generally finer grain size of the red earth suggests a weaker transporting wind and or a more remote source the latter implies a smaller extent of deserts than in the quaternary the high degree of similarity between the geochemical properties of the red earth and loess samples seems to suggest a rather similar source areas and comparable dust transporting trajectories the removal of the dust deposits from groundwater influence and the increase in grain size at 3 6 ma bp are attributable to both tectonic and climatic causes the initiation of these phenomena corresponds to an intensive uplift of the tibetan plateau and also to a simultaneous uplift of the sedimentary basins in the surrounding areas it is also approximately synchronous with an increase in eolian mass accumulation rate in the north pacific both suggesting an increased continental aridity in the asian dry lands and an increasing intensity of transporting winds

pedostratigraphy and paleomagnetism of a 7 0 ma eolian loess red clay sequence at lingtai loess plateau north central china and the implications for paleomonsoon evolution abstract a 305 m thick loess red clay sequence was discovered recently at lingtai which is located in the middle part of the chinese loess plateau it consists of a complete pleistocene loess soil sequence with a thickness of about 175 m and 130 m of tertiary red clay deposits the red clay sequence at lingtai is the thickest one presently known in the loess plateau field observations show that the lingtai red clay contains over 110 couplets of pedogenic b horizons and horizontal carbonate nodule horizons and that it can be regarded as an extremely thick soil complex paleomagnetic studies of 680 samples suggest that the basal age of the lingtai loess red clay sequence is about 7 05 ma grain size analysis of samples taken at 3 3 cm intervals indicates that the red clay has the same sedimentological characteristics as those observed in the loess thus suggesting a wind blown origin of the tertiary red clay and continuous atmospheric dust deposition in the loess plateau during the last 7 05 ma the pedogenic characteristics of the paleosols within the pleistocene loess and the b horizons in the red clay suggest that the east asia summer monsoon in the latest miocene may have already been slightly stronger than that during the holocene this implies that at about 7 5 ma bp the tibetan plateau could have been uplifted to a critical height in maintaining the east asia summer monsoon system observations of the loess red clay sequence also suggest that the long term changes in the east asia summer monsoon strength have been nonlinear since the latest miocene

a new magnetostratigraphic framework for late neogene hipparion red clay in the eastern loess plateau of china abstract mammalian fossils especially the hipparion fauna found in the red clay of the loess plateau are of immense value for reconstructing late neogene paleoecology and paleoclimatology in northern china the lack of a precise chronological framework for these fossil sites has impeded our understanding of the evolution of the chinese mammalian fauna their correlation with european mammalian units and the retrieval of paleoclimatic information in this study a field survey of regional stratigraphy in the baode area of shanxi was carried out and three profiles tanyugou yangjiagou i and yangjiagou ii of late neogene deposits were selected for detailed investigation a new chronological framework of the late neogene sequences in the baode area is established by means of paleomagnetism our results show that the red clay accumulation in the baode area began at least 7 23 ma ago deposition continued to the superposed jingle formation the most continuous and complete exposure of the jingle formation known to date was identified and dated to 2 72 5 34 ma a lithological distinction between the jingle formation and the underlying baode formation forms a clear boundary in the red clay that is not coincident with the miocene pliocene boundary documented elsewhere three rich fossil layers are found in the yangjiagou ii profile and dated to 6 43 6 54 ma 6 83 6 86 ma and 7 15 7 18 ma respectively with the application of three different demagnetization techniques the matuyama gauss geomagnetic reversal boundary was identified in a transitional unit between loess and typical red clay deposits a lock in depth of as large as 6 8 m corresponding to ca 65 ka was inferred but remains unexplained

pliocene pleistocene climatic change recorded in fluviolacustrine sediments in central china abstract a 250 m thick section located in the guanzhong basin central china consisting of a loess paleosol sequence in the upper part and fluviolacustrine sequence in the lower was selected for this study which involves documenting the climate transition around the global glacial initiation about 2 5 ma and focuses on the climatic information recorded in the fluviolacustrine sediments paleomagnetic study indicates that the entire shijiawan section developed during the past 3 08 ma and the fluviolacustrine sequence spans the time interval of 3 08 1 9 ma sedimentary analysis shows that alluvial facies dominates the so called fluviolacustrine sequence with strong cyclicity pollen study combined with stable carbon isotope analysis of organic matter displays profound changes of the paleovegetation in response to climate forcing during the period of 3 0 2 7 ma persistent steppe vegetation and elephant fossil fauna suggest long lasting dry and warm climate conditions with little change from 2 7 to 2 5 ma sparse steppe flora manifests a striking climatic deterioration the first thick loess like layer in the fluviolacustrine sequence consistent with the commencement of the loess deposition in the loess plateau marks a rapid and great intensification of the siberian cold high pressure regime at 2 6 ma afterwards the regional vegetation fluctuated between dry steppe and forest grasslands in agreement with loess paleosol alternations corresponding to the climatic oscillations between cold dry and warm wet such secular climate variation patterns demonstrate the predominant influence of global glacial and interglacial forcing on the regional climate system of the east asian monsoon the late pliocene climate warm and dry is distinct from the harmony of temperature with precipitation i e cold with dry and warm with wet which is fully exhibited throughout the past 2 6 ma thus the time of the first global glaciation must have involved a rapid reorganization of the regional climate regime and the onset of the modern east asian monsoon

geochemical evidence for the provenance of middle pleistocene loess deposits in southern china the provenance of middle pleistocene loess in the middle and lower reaches of the yangtze river the most intensively investigated loess deposits outside the loess plateau region in china remains controversial identification of the provenance will provide crucial insight into the environmental implications of this valuable sedimentary archive and into the potential role of the east asian winter monsoon in transporting the dust from deserts in the asian interior in this study geochemistry was used to compare the provenance of loess in the lower reaches of the yangtze river in southern china with that inferred for loess deposits on the loess plateau in northern china compared with samples from the loess plateau the 20 mm fraction in the loess deposits of southern china has higher tio2 al2o3 zr nb zr al zr ti zr hf y al and lan smn ratios and lower eu eu th nb y nb and al nb ratios the clear distinction in immobile element ratios between samples from the two regions indicates that the loess deposits in the two regions have different provenances the inferred difference in source area is also supported by variations in the major element composition of bulk samples obtained in this study and collected from published data these lines of evidence indicate that the deserts in the asian interior are not the primary provenance for the southern loess it is suggested that the adjacent floodplains to the north of yangtze river are the dominant dust sources and the occurrence of sustained loess deposits in the lower reaches of the yangtze river currently an area of northern subtropical climate is an indication of local aridification and strengthened winter monsoon activity during glacial periods as a regional response to the middle pleistocene climate transition around 0 8 ma the role of the east asian winter monsoon in transporting the dust from northern deserts to southern china has been overestimated in previous studies

how does chinese loess become magnetized despite nearly three decades of paleomagnetic research on the extensive chinese loess deposits a convincing explanation has yet to be developed for how chinese loess becomes magnetized to address this problem we conducted re deposition experiments using weakly consolidated holocene chinese loess that was disaggregated in the laboratory and compare our results with published paleomagnetic data we simulated a depositional remanent magnetization drm associated with dry deposition of eolian sediments and a post depositional remanent magnetization pdrm in which the sediment was water saturated after deposition the simulated drm faithfully records the declination of the applied field but with systematic inclination flattening addition of minor water slightly improves recording of the applied field but inclination flattening persists reliable recording of the applied field occurs for pdrm simulation in water saturated sediment our synthesis of paleomagnetic data from chinese loess indicates that time averaged paleomagnetic directions are often indistinguishable from the expected geocentric axial dipole gad field but in many cases inclinations are shallower than for a gad field we conclude that the chinese loess is magnetized by a combination of drm and pdrm mechanisms with water content providing the dominant control on which mechanism aligns the detrital mineral fraction where pedogenesis causes neoformation of magnetic minerals an additional chemical remanent magnetization crm will occur the magnetization of chinese loess therefore appears to be controlled by a complex time varying combination of drm pdrm and crm mechanisms

apparent timing and duration of the matuyama brunhes geomagnetic reversal in chinese loess the matuyama brunhes mb geomagnetic reversal in chinese loess has been studied extensively as an important boundary for land ocean stratigraphic and paleoclimatic correlations however the apparent timing and duration of the mb boundary remain controversial in chinese loess deposits due to its inconsistent stratigraphic position and the uncertain chronologies here we synthesized high resolution paleomagnetic records from four loess sequences in the central chinese loess plateau and synchronized the loess paleosol chronology by matching the grain size variations to orbitally tuned grain size time series the synthesized paleomagnetic results reveal consistent features of the mb transition in chinese loess including the stratigraphic position l 8 s 8 transition timing 808 826 ka duration 14 16 ka and rapid directional oscillations compared with the mb transition in marine records 770 775 ka the timing of the mb transition is relatively older and longer in chinese loess due to a complex interplay between different remanence acquisition mechanisms which occurred during the course of postdepositional physical and chemical processes

paleomagnetic age of the tangxian planation surface northwestern zhongtiao shan of the shanxi graben system north china abstract a numerical formation age for the tangxian planation surface txps in north china is still controversial the txps beveled across paleoarchean basement rocks is overlain by late cenozoic conglomerate aeolian red clay and loess the magnetostratigraphy of two late cenozoic deposition sections is established and two other sections are recorded and measured in this work the magnetostratigraphy indicates six normal magnetozones n1 to n6 and six reverse magnetozones r1 to r6 these magnetozones are correlated to chron c1n through c2an 1r indicating that the txps was formed at 3 12 3 03 ma the characteristics of the zhongtiao shan tectonic uplift and its relationship with the tibetan plateau and ordos block are discussed in terms of tectonic uplift the txps formation and accumulation of the late cenozoic sediments are mainly controlled by tectonic activities the formation and uplift of the txps with a lag in the shanxi graben system is consistent with the activities of the tibetan plateau and ordos block implying that the ne extension of the tibetan plateau epeirogenic uplift advances successively

the onset of extensive loess deposition around the g m boundary in china and its palaeoclimatic implications abstract in northern china the red clay loess contact is palaeomagnetically defined at about the gauss matuyama boundary the red clay formation has recently been proposed as mostly of wind blown origin and can be interpreted as having been formed under climatic conditions of continuous warmth punctuated by small amplitude oscillations the shift from red clay development to extensive loess deposition exhibits a 3 fold abrupt increase in aeolian dust deposition rate and marks the beginning of frequent and chaotic climatic fluctuations this event implies a large scale reorganization of the atmospheric circulation over east asia in particular the northward shift and intensification of the siberian high which may have resulted from a dramatic uplift of the tibetan plateau compared to another climatic shift recorded by the chinese loess deposits which occurred at about the upper boundary of the olduvai subchron the red clay loess shift is much more pronounced and recognizable in the field it appears that in regional stratigraphic studies the g m magnetic reversal has a better correlation potential than the upper olduvai

mechanism of palygorskite formation in the red clay formation on the chinese loess plateau northwest china abstract the morphological characteristics and microstructures of the authigenic palygorskite occurring with smectite and carbonate minerals in the late miocene red clay formation on the chinese loess plateau have been investigated with the powder x ray diffraction xrd scanning electron microscopy sem and high resolution transmission electron microscopy tem the xrd results indicate that the red clay sediments contain quartz feldspar calcite dolomite illite kaolinite chlorite palygorskite and smectite and sem analyses show that palygorskite is a common component delicate palygorskite fibers radiate from the margins of platy smectite suggesting a pedogenic origin during the weathering of pre existing smectite a process that involved intense dissolution of the smectite and an adjustment in its structure moreover palygorskite occurs as coatings pore fillings and pore bridging cements among dolomite rhombs suggesting that the fibrous palygorskite was formed by a direct dolomite precipitation from pore fluids mostly after dolomite crystallization there is evidence to show that these two mechanisms took place synchronously in the red clay formation and that the two processes are related under alkaline conditions with high ph 8 0 fluids rich in magnesium magnesium ions occupy the interlayer positions in the smectite and this results in a misfit between the mg octahedral sheet and the smectite layer thereby allowing interaction between the magnesium ions and smectite layers and a reorganization of the structure to form palygorskite then with this kind of palygorskite as a crystal nucleus more palygorskite grows through a direct chemical deposition process according to previous studies the red clay sediments experienced a steady dry warm climate with periods of high rainfall and evaporation the warm climate would have increased the rate of weathering of minerals and subsequently enhanced the ions content and ph in the soil solutions during dry periods this soil environment is favorable for smectite transformation and palygorskite deposition this study has improved our understanding of the environmental and paleoclimatic changes during the time that palygorskite formed in the arid soils of the chinese loess plateau

magnetic stratigraphy of the danube loess a composite titel stari slankamen loess section over the last one million years in vojvodina serbia abstract in europe the most complete loess paleosol sequences over the past million years are preserved in the serbian part of the danube river drainage basin the similarity in stratigraphy and climatic cycles between the serbian and the chinese loess sequences suggests that the loess deposits in these two regions could play an important role in the study of intercontinental climatic correlations and linkage however previous magnetostratigraphic studies of the serbian loess mainly conducted using the alternating field af demagnetization approach show significant differences with the chinese loess especially the stratigraphic positioning of the matuyama brunhes boundary mbb here we conduct a detailed magnetostratigraphic investigation of a composite titel stari slankamen loess section in the vojvodina northern serbia using thermal and hybrid demagnetization methods aiming to establish new chronological constraints for the danube basin loess based on the analyses of the mineral magnetic properties anisotropy of magnetic susceptibility progressive thermal and hybrid demagnetization the mbb was determined within s8 broadly consistent with the mbb position seen in the chinese loess present evidence supports the hypothesis that the overall normal polarity in the upper part of l9 with a thickness of 2 1 m was possibly caused by a combination of the remagnetization of remanence carrying coarse grained magnetite during the brunhes normal chron and bioturbation during the forming of the overlying paleosol s8 thus our magnetostratigraphic results provide solid chronological evidence for the coherence of pedostratigraphy and climatostratigraphy for the loess deposits in the danube basin and china the synchronous occurrence of the strongest developed paleosol s5 corresponding to miss 15 13 and the least weathered thick loess unit l9 corresponding to miss 24 22 in the two regions confirms that extreme climatic events during these two intervals are possibly common features of the climate in the northern hemisphere at those times