partly pedogenic origin of magnetic variations in chinese loess quaternary sequences of interbedded aeolian silts loess and buried soils palaeosols potentially provide one of the best terrestrial records of past climates1 5 magnetic susceptibility variations in loess and palaeosol sequences from china are strongly correlated with climate induced fluctuations of oxygen isotope ratios in deep sea sediments2 4 6 8 as an explanation of this correlation it has been suggested that the recorded variations in magnetic susceptibility depend primarily on the degree of dilution by non magnetic bulk loess constituents of a uniform magnetic assemblage derived from remote but unknown sources6 8 it has also been suggested that such a model involving changes in the accumulation rate of loess superimposed on a constant flux of magnetic particles provides a relative geological timescale through the control of loess deposition by astronomically modulated climate fluctuations7 here we report a preliminary test of this model using rock magnetic properties especially sensitive to variations in magnetic grain size our results show that palaeosols are characterized by much finer magnetic grain size assemblages than are the intervening loess units this suggests that a simple model based on constant magnetic influx and dilution by variable amounts of non magnetic loess is inadequate our magnetic measurements establish the close comparability of the fine grained magnetic minerals in the palaeosol samples to those in contemporary soils and thus point to a partially pedogenic origin for the magnetic mineral assemblages in the palaeosols

magnetic susceptibility of soils along a lithotoposequence in southeast iran abstract magnetic susceptibility is a simple and quick technique to determine soil properties and to describe soil forming processes knowledge about factors affecting data helps better interpretation magnetic susceptibility of soils along a lithotoposequence was studied in this research in order to investigate the effects of soil forming factors parent material and relief and processes on the content and its vertical distribution the study area is a transect from jiroft to kahnooj area south kerman province iran rock pediment mantled pediment inselberg alluvial fan alluvial plain and flood plain landforms with igneous parent materials gabbro diorite and granite were selected in the area thirteen representative pedons on different geomorphic positions were studied low frequency lf values ranged from 193 1 10 8 m3 kg 1 to 2704 2 10 8 m3 kg 1 in studied soils and decreased with increasing diamagnetic material contents mean lf values in soils formed on gabbro diorite and granite parent rock were 1700 10 8 m3 kg 1 515 22 10 8 m3 kg 1 and 352 53 10 8 m3 kg 1 respectively frequency dependent of soils in the range of 0 06 to 1 05 showed that coarse multi domain grains inherited from igneous parent material were the main source of lf in the area under study both increasing and decreasing trends of lf with depth were observed decreasing trend of lf with depth was due to illuviation of diamagnetic material into subsurface layers on the other hand increasing lf with depth was attributed to the primary ferrimagnetic material inherited from igneous parent material alluvial plain 320 44 10 8 m3 kg 1 and mantled pediment 328 50 10 8 m3 kg 1 showed low values of lf due to high amounts of soluble salts anhydrite and calcium carbonate investigated in these geomorphic positions a positive significant relationship r2 0 018 r 0 27 p

a deep sea benthic community exposed to strong near bottom currents on the scotian rise western atlantic abstract this paper gives an overview of the structure of a benthic community at 4626 m depth on the nova scotian continental rise here abundances of polychaetes bivalves isopods and tanaids are conspicuously high compared to those reported from comparable depths bacterial numbers and atp concentrations are also high we suspect that these anomalous abundances result from enhanced food availability caused by the strong near bottom currents that flow through the area the polychaete and bivalve faunas have few adults and high species dominance suggesting that currents create large scale sediment transporting disturbances the composition of the crustacean fauna supports this inference in that it is dominated by forms that can enter the seabed and thereby escape adverse conditions on the sediment surface

bathymetric patterns of α and β diversity of harpacticoid copepods at the genus level around the ryukyu trench and turnover diversity between trenches around japan abstract the diversity of harpacticoid copepods was investigated around the ryukyu trench 430 7150 m which lies below an oligotrophic subtropical ocean the diversity which is based on the number of genera and shannon diversity decreased with increasing water depth the community structure of harpacticoids gradually changed as the water depth increased from the bathyal zone to the hadal zone turnover diversity values were equally high between the trench slope trench floor and abyssal plain we compared the harpacticoid assemblage obtained from the ryukyu region with the assemblage from a region around the kuril trench kitahashi et al 2013 turnover diversity values between the two regions diversity were relatively low at shallow depths but they increased with increasing water depth and reached their maximum between the trench floors and abyssal plains these findings indicate that the bathymetric patterns of harpacticoid assemblages differ among regions and that these discrepancies reflect differences in environmental conditions such as primary productivity level

sedimentation under deep sea storms fast currents high concentrations of suspended sediment and grooved mud beds are associated with erosion in frequent abyssal storms where a fast deep mean flow is augmented or reversed by intense intermittent currents this occurs about 5 km below the gulf stream or its rings the waning phase of a storm results in development of bedforms and rapid deposition of a mud blanket several other regions of the world ocean display evidence of abyssal storm activity

magnetic imprints of pedogenesis in planosols and stagnic alisol from bulgaria iron in its diverse forms in soils is an important indicator of a number of past and or ongoing environmental processes iron oxide mineralogy pertinent to a particular soil type could be obtained with high resolution using magnetic methods planosols are a particular soil type characterized by surface water logging leading to development of great textural differentiation with depth this study presents magnetic investigation on three planosols and a stagnic alisol from bulgaria combined with conventional chemical extraction methods oxalate citrate dithionite and soil property characterization ph grain size fractions and organic carbon content extensive magnetic analyses on high resolution sampled depth profiles have been done for determination of iron oxyhydr oxide minerals their stability and variations of effective magnetic grain size with depth zones of intensive iron oxides dissolution the topmost soil horizons are magnetically depleted in the content of strongly magnetic minerals but the paramagnetic content detected through the ratio 77 293 is enhanced accordingly bleached eluvial horizons however contain stable crystalline magnetite maghemite fraction albeit in a trace amounts we ascribe this to the processes of lessivage and translocation of magnetite maghemite from the topmost humus horizon the main results on iron oxide mineralogy suggest that thin humus horizons are enriched with pedogenic maghemite thermal behavior of magnetic susceptibility suggests that ferrihydrite is present in humus and eluvial horizons of all profiles in illuvial horizons of planosols the common mineral is lepidocrocite while in alisol al substituted hematite planosols and stagnic alisol contain both poorly crystalline and well crystalline iron oxides increasing precipitation and weathering leads to higher proportion of well crystalline pedogenic phases in the alisol profile

the huguang maar lake a high resolution record of palaeoenvironmental and palaeoclimatic changes over the last 78 000 years from south china abstract a series of seven piston cores from the huguang maar lake situated near the south china sea coastline provides insight into regional palaeoenvironmental and palaeoclimatic changes in southern china over the last 78 000 years the data set comprises a high resolution record of magnetic susceptibility dry density and water content total organic carbon and inorganic carbon total nitrogen biogenic silica bsio2 and palynological results the time scale was developed by ams 14c dating of 17 terrestrial plant macro fossils during the last glacial the huguang record is characterised by an alternation of more temperate and humid periods from 78 to 58 and 48 to 40 5 ka bp and periods with predominance of grassland vegetation and possibly lowered lake level from 58 to 48 and ca 40 5 to 15 ka bp the huguang data have been compared to regional marine and terrestrial records in order to discuss variability of the south east asian monsoon system for most of the last glacial period the huguang proxies do not exhibit marked millennial scale variability as known from some long se asian and many north atlantic records this picture changes at about 15 cal ka bp when the huguang and greenland records appear to correlate well a short climatic reversal which is assumed to reflect a younger dryas type event is well recorded in the huguang record during the holocene the huguang multi proxy data show a much higher variability than during the last glacial stage probably reflecting at least for the early mid holocene fluctuations in monsoon activity however the last 4000 years of the sediment record are clearly influenced by enhanced human activity and thus difficult to interpret in terms of palaeoclimate change

meiofauna towards the south sandwich trench 750 6300m focus on nematodes abstract meiobenthos excluding foraminifers from the south sandwich trench was studied in sediment samples collected by multiple core muc or multiple grab mg sampling stations were chosen along a depth transect that covered the continental slope and abyssal plain towards the trench water depths from 747 to 6319 m total abundance and biomass of meiobenthos ranged between 354 and 1675 ind 10 cm 2 and between 16 3 and 80 8 g c 10 cm 2 respectively standing stock decreased though not linearly with increasing water depth biomasses and densities were situated above the world ocean s regression line of meiobenthic stocks against water depth and higher on the trench floor 354 930 ind 10 cm 2 18 7 g c 10 cm 2 at 6300 m compared to most other oceans trench regions this observation confirms earlier results from the antarctic continental margins that antarctic meiofauna is characterised by dense populations in which nematodes predominate over the other taxonomic groups 87 98 of total abundance taxonomic investigations at genus level revealed that chromadoridae monhysteridae desmodoridae desmoscolecidae xyalidae and cyatholaimidae were dominant most of the nematode genera in total 94 occurred in all depths with only a slight distinction between the shallow daptonema dichromadora and molgolaimus preferentially at 750 2300 m and deep with tricoma preferentially from 3000 m on the shallow communities were comparable to those from the weddell sea continental margin the sediments at 2300 6300 m harboured in big lines similar compositions as abyssal and trench communities worldwide two main morph clusters were distinguished among the south sandwich trench nematodes plump nematodes with average l w 9 belonging to the taxonomic similar selective deposit feeding genera of the desmoscolecida and comparable slender nematodes l w 26 biomass size class 4 to 2 such as monhystera acantholaimus daptonema dichromadora molgolaimus microlaimus and some species from paracanthonchus mixed among mainly selective and epistratum feeding modes they formed the bulk of the trench community the results did not fit well with the general decrease in standing stock with increasing water depth and distance from the continental shelf similarly nematode size length from 124 to 2991 m biomass from 0 023 to 0 042 g dwt did not show clear bathymetric trends the lack of the usual deep sea trends of structural characteristics of meiofauna in general density total biomass taxon composition and functional attributes of nematodes morphometrics biomass trophic guild structure and maturity index is explained by the particularly complexity of the sedimentary environment of the south sandwich trench which was the result of physical processes turbidites bioturbation activity by invertebrate taxa and food supply along the depth transect

flexural uplift of a lithospheric slab near the vema transform central atlantic timing and mechanisms abstract the vema transverse ridge vtr is a prominent long and narrow topographic anomaly that runs for over 300 km along a sea floor spreading flow line south of the vema transform at 11 n in the atlantic it rises abruptly about 140 km from the axis of the mid atlantic ridge mar in 10 myr old crust and runs continuously up to 25 myr old crust it reaches over 3 km above the predicted lithospheric thermal contraction level it is absent in crust younger than 10 myr thus the uplift of the vtr must have ended roughly 10 ma the vtr is interpreted as the exposed edge of a flexured and uplifted slab of oceanic lithosphere that was generated at an 80 km long mar segment based on satellite gravimetry imagery this mar segment was born roughly 50 ma and increased its length at an average rate of 1 6 mm yr multibeam data show that the mar parallel sea floor fabric south of the vtr shifts its orientation by 5 to 10 clockwise in 11 12 myr old crust indicating a change at that time of the orientation of the mar axis and of the position of the euler rotation pole this change caused extension normal to the transform followed between 12 and 10 ma by flexure of the edge of the lithospheric slab uplift of the vtr at a rate of 2 to 4 mm yr and exposure of a lithospheric section vema lithospheric section or vls at the northern edge of the slab parallel to the vema transform ages of pelagic carbonates encrusting ultramafic rocks sampled at the base of the vls at different distances from the mar axis suggest that the entire vtr rose vertically as a single block within the active transform offset a 50 km long portion of the crest of the vtr rose above sea level subsided was truncated at sea level and covered by a carbonate platform subaerial and submarine erosion has gradually removed material from the top of the vtr and has modified its slopes spreading half rate of the crust south of the transform decreased from 17 2 mm yr between 26 and 19 ma to 16 9 mm yr between 19 and 10 ma to 13 6 mm yr from 10 ma to present the slowing down of spreading occurred close in time to the change in ridge transform geometry suggesting that the two events are related a numerical model relates lithospheric flexure to extension normal to the transform suggesting that the extent of the uplift depends on the thickness of the brittle layer consistent with the observed greater uplift of the older lithosphere along the vtr

color variations of the quaternary red clay in southern china and its paleoclimatic implications abstract the red clay and red weathering crust are widely distributed in southern china to study the possible relationship between soil color and paleoclimatic environment three color parameters lightness l redness a and yellowness b of twelve quaternary red clay qrc profiles in southern china were measured using a colorimeter colors of the qrc profiles vary vertically a and b generally increase downward and l decreases downwards colors of the qrc also show spatial variation a and b generally increase towards the equator whereas l increases away from it both a and b are positively significantly correlated with clay

stratigraphy petrography and paleogeography of the late paleozoic diamictites of the lesser himalaya abstract the late paleozoic diamictites of the lesser himalaya are one of its most important stratigraphic horizons because they are very useful in stratigraphic correlation of its unfossiliferous rocks and in paleogeographic reconstruction the clast petrography of the diamictites from garhwal and the eastern himalaya as well as of other diamictites clearly indicates a provenance from largely late precambrian early paleozoic rocks of the lesser himalaya a widespread glacio marine environment with occassional volcanism and probably turbidity currents in certain parts of the diamictite association has been postulated for their origin paleogeographic reconstruction of the lesser himalaya during the late paleozoic has revealed a homotaxial relationship between its diamictites and the gondwana diamictites of peninsular india these were extensively though unevenly deposited upon the eroded surface of orogenically deformed late precambrian early paleozoic rocks of the lesser himalaya and they belong to different tectonic units which are superposed upon each other as a consequence of the himalayan orogeny

characterisation of soils by mineral magnetic measurements processes of iron mineral authigenesis diagenesis and dissolution in interaction with primary inputs of iron minerals act to produce vertical differentiation of soil magnetic properties thus magnetic iron oxides in common with other iron forms may both respond to and reflect soil forming processes investigation of the degree of detectable and persistent magnetic differentiation within different soil materials can provide insights into the nature and direction of distinct sets of soil processes evidence of clear association between magnetic variation and discrete types of soil environment also has applied significance in several areas of environmental study for example the observed magnetic variation can be used to discriminate between individual soils and soil horizons for the purposes of soil surveying sediment tagging and tracing and empirical modelling of source sediment linkages this paper reports the use of mineral magnetic techniques to characterise the iron oxide assemblages within soils of varying type and provenance the effect of different pedogenic regimes have been investigated through measurement of a range of magnetic parameters including magnetic susceptibility frequency dependent susceptibility and anhysteretic and saturation remanences contrary to current pedological thought but in accord with other magnetically based studies e g mullins the presence of magnetite maghemite typically of superparamagnetic single domain grain size within soils has been found to be an extremely widespread phenomenon its contemporary neoformation within the soil environment is inferred however the input of artificially generated ferrimagnetic material is indicated for one of the magnetically enhanced soils examined here and the possibility of extraneous sources of magnetite in topsoils should be considered before pedogenic processes of magnetic enhancement are inferred from the data presented discrimination of industrially derived magnetic particles appears possible on the basis of their very low levels of frequency dependent susceptibility fd low anhysteretic remanence arm and dissociation from the finer clay sized not the formation but the active dissolution of ferrimagnetic minerals is indicated for soils affected by the processes of gleying and podsolisation eluvial horizons of podsolised profiles demonstrate almost total loss of detectable magnetic content variations in the form of the iron reprecipitated in the underlying illuvial layers may reflect differences in the pedological characteristics of these horizons within gleyed waterlogged soils processes of magnetite dissolution appear to be grain size specific preferential reduction of those grains of ultrafine superparamagnetic and fine single domain magnetic grain size is indicated where soil forms a major contributor to catchment sediment loads this has significance in the area of source sediment modelling soil derived from permanently wet or highly leached catchment areas is unlikely to contribute to peaks in the magnetic content of deposited sediments further only those erosional processes that operate at a faster rate than those of magnetic depletion will have the capacity to produce peaks in sediment ferrimagnetic concentrations such as have been observed within the historical magnetic record

pleistocene climates in china dated by magnetic susceptibility the magnetic susceptibility of loess and interbedded soils in central china varies with the degree of pedogenesis and serves as a proxy measure of climate the concentration of magnetic minerals in the sediment is inversely proportional to sedimentation rates throughout the brunhes epoch susceptibility measurements combined with the reversal stratigraphy provide a time scale that is independent of astronomic chronology on this scale the susceptibility record closely parallels the oxygen isotope fluctuations in deep sea sediments suggesting a close interdependence of the chinese dust falls the volume of land based ice and global climate

use of mineral magnetic measurements to investigate soil erosion and sediment delivery in a small agricultural catchment in limestone terrain abstract understanding sediment delivery at the hillslope scale requires information on the spatial distributions and magnitudes of erosion and deposition empirical models such as the rusle may be useful for predicting erosion but are poorly suited for quantifying deposition cesium 137 cs 137 is useful for quantifying both erosion and deposition but is costly to inventory over a large area and directly gauges soil redistribution only for recent decades the use of rapidly acquired magnetic measurements represents a relatively new potential means of mapping and measuring soil redistribution in this study variations in surface magnetism are analyzed to determine patterns of erosion and sedimentation in a small agricultural catchment in northwestern alabama usa magnetic indicators of erosion are combined with published soil morphology cs 137 and short term suspended sediment data from this former experimental watershed to evaluate long term sediment delivery all magnetic parameters measured could be related to soil erosion although their patterns in space are not identical magnetic evidence suggests approximately 30 cm of soil loss on the steepest mid slope portions of the catchment distributing soil loss across space according to magnetic patterns gives average long term values lower than a prior estimate based on cs 137 data long term sediment delivery calculated using soil morphology to determine depositional volume ranges up to 45 depending on the magnetic parameter used to index soil loss and assumptions regarding deposit geometry these results suggest the need for continued refinement of magnetic techniques for purposes of erosion model validation and general sediment tracing applications

lithological factors affecting magnetic susceptibility of subtropical soils zhejiang province china abstract magnetic susceptibility was measured on subtropical soils formed on a range of parent materials in zhejiang province china to demonstrate the influence of parent material lithologies on the amount and vertical distribution of in the soils we found that the values of soils vary by up to two orders of magnitude with their parent material lithologies soils formed on igneous rocks with high values showed high absolute and distinctly decreased compared with values of parent materials the values of soils formed on basalt andesite and granodiorite were 250 10 8 m 3 kg 1 the values of soils formed on granite and other neutral and acid igneous rocks ranged from 50 10 8 to 120 10 8 m 3 kg 1 in most of the soils formed on sedimentary rocks enhancement in upper horizons of soils was found compared with parent material this enhancement was believed to be pedogenic formation of superparamagnetic sp stable single domain ssd magnetic grains which are characterized by high values of frequency dependent susceptibility fd and anhysteretic remanent magnetization arm soils formed on sedimentary rocks with a very low initial and iron content showed a low value throughout the profile it was found that there is a highly significant relationship between the values of soils and their dithionite citrate bicarbonate solution dcb soluble iron contents fe d the values of soils in chronosequences formed on alluvium and two marine deposits increased as soils became older it is suggested that the values can be used as a tool for determining the relative age in chronosequence studies

soil parent material relationship in a mountainous arid area of kopet dagh basin north east iran abstract the effects of parent rock types on soil evolution in arid areas were studied in a sequence of soils derived from different lithologies in the kopet dagh basin northeastern iran using micromorphology clay mineralogy magnetic susceptibility and physico chemical properties the selected parent rocks and associated soils were shale haplocalcids claystone haplotorrerts gypsiferous marl haplogypsids limestones haplocalcids and torriorthents siltstone and sandstones torriorthents the results showed that the properties and development of soils were mainly affected by grain size and mineralogy of parent materials soil magnetic susceptibility lf variations were attributed to the types of parent material and pedogenic processes redistribution of calcite and gypsum in soil profiles and natural and pedogenic formation of ferrimagnetic minerals were responsible for lf variations the soils clay mineral origins were found to be mainly of inheritance from parent materials smectite was the dominant clay mineral of the most soils based on the micromorphological index of soil evolution miseca the soils studied were categorized into weakly developed orthents weakly to moderately developed aridisols gypsids and calcids and moderately developed soils including calcids and torrerts the degree of microstructure development alteration of weatherable minerals and calcitic features were the most important criteria influencing assessment of soil development degree by miseca index the vertic features were only observed in soils of claystone in which there were considerable amounts of clay and smectite high amounts of gypsum and low smectite content were mainly responsible for the lack of vertic behavior in other fine grained soils derived from shale and marl

earthquakes and deformational structures seismites in holocene sediments from the himalayan andaman arc india soft sediment deformational structures from the himalayan arc caused by episodic earthquake recurrences during the holocene recent are produced by the ongoing tectonic processes these small scale subtle structures occur along some major thrusts in the garhwal himalaya and vary from normal faults in the lower zone to compressional structures in the middle zone along the main central thrust in the tons valley the latter includes isoclinal angular kink and disharmonic folds with discrete displacements along their axial surfaces thrusts with decollement listric and overstep thrusts in duplex style and load slumping the upper zone is marked by very low angle thrusts with left lateral displacement and associated displacement shears d riedel shears r and thrust shears p as well as small scale sporadic kinks three zones reveal changing tectonic character from gravity tectonics in the lower zone to compression in both the middle and upper zones with the maximum principal stress 1 oriented n60 to n110 respectively along the tons thrust post depositional structures include drag along normal fault zone characterized by d r and p shears and conjugate fractures that provide localized orientation of stresses 1 at 75 n60 2 at 12 n280 and 3 at 12 n290 earthquake induced liquefaction and subtle variations in physiomechanical properties of soft sediments have primarily controlled the deformational pattern due to localized tectonic stresses ground and sediment deformations during two earthquakes in the himalayan andaman arc provide additional support for the seismogenic origin of such structures preserved in loose or consolidated sediments

mineral magnetic properties of chinese paddy soils and its pedogenic implications abstract magnetic susceptibility ms of paddy soils hydragric anthrosols and their corresponding dryland soils formed on the same parent materials in zhejiang province of eastern china were measured in order to understand better magnetic profile discrimination and pedogenic magnetic minerals in paddy soils magnetic measurements showed that the ms values of paddy soils were much lower than those of dryland soils formed on the same parent materials the higher the ms value of the original dryland soil is the more remarkable the decrease in the ms value is when the soil is put under rice cultivation gleyed paddy soils exhibited very low ms value

tianzhushania spinosa and other large acanthomorphic acritarchs of ediacaran period from the infrakrol formation lesser himalaya india covering a time span from ediacaran base of blaini pink carbonates to early cambrian base of tal group the krol belt in the lesser himalaya india occurs as a series of synclines from solan himachal pradesh in the north west to nainital uttarakhand in the south east various lithostratigraphic divisions of this belt reveal many palaeobiological entities namely cyanobacteria algae acritarchs small shelly fossils and trace fossils globally large acanthomorphic acritarchs of the ediacaran period are used as significant biostratigraphic tools for global correlation in the krol belt reports of acanthomorphic acritarchs from the infrakrol and krol a formations of the krol group have further supported this notion this paper reports well preserved microfossils including acanthomorphic acritarchs sphaeromorphic acritarchs coccoids namely tianzhushania spinosa t polysiphonia papillomembrana compta schizofusa sp gloeodiniopsis lamellosa sphaerophycus medium and the unnamed forms a b and c from the chert nodules of the infrakrol formation exposed in the nainital syncline of the kumaun lesser himalaya a biostratigraphic correlation based on acanthomorphic acritarchs suggests that the infrakrol formation is coeval to the lower tianzhushania assemblage zone of the doushantuo formation of south china tianzhushania and papillomembrana are significant additions to the previous record of the ediacaran acanthomorphic acritarchs from the lesser himalaya of india and provide an independent evidence for construction of both biozonation scheme and paleogeography

magnetic susceptibility of the quaternary red clay in subtropical china and its paleoenvironmental implications abstract magnetic susceptibility lf and other magnetic parameters of 11 typical profiles of quaternary red clay qrc in subtropical china were measured lf curves of the qrc profiles show similar vertical variations lf of the uppermost yellow brown earth ybe and uniform red clay urc of the profiles is high mostly ranging from 50 to 150 10 8 m 3 kg 1 that of the reticulate red clay rrc sharply decreases downwards especially in the lower rrc lrrc with dense reticulate pattern lf is often less than 10 10 8 m 3 kg 1 grain size characteristics and geochemical properties of the qrc suggest that the sharp decrease of lf in the rrc is not related to sudden change of parent materials but to the formation of the reticulate pattern further study indicates that pedogenic fine ferrimagnetic minerals fm superparamagnetic particles sp and or stable single domain ssd are the main magnetic carriers of the qrc the ybe and urc with higher lf show low coercivity and magnetic soft behavior the rrc especially the lrrc with weak magnetism shows high coercivity and magnetic hard behavior the temperature dependent susceptibility tds of the qrc suggests that the dominant type of fm in the ybe and urc is pedogenic maghemite the rrc especially the lrrc however contains little maghemite but a trace amount of lithogenic multi domain md magnetite inherited from the parent rock during post depositional hydromorphic processes pedogenic maghemite was more easily dissolved than hematite which caused the sharp decrease of lf in the rrc as lf of the qrc was mainly controlled by the intensity of hydromorphic processes rather than the weathering degree lf of the qrc in subtropical china cannot accurately indicate the paleoclimate during the quaternary period when the red clay was initially formed

the hidden nature of parent material in soils of italian mountain ecosystems abstract soils with andic features are known to be very important as regards both ecosystem fertility and susceptibility to land degradation in recent years there has been an increasing number of finds of these soils in non volcanic mountain ecosystems nvme in different parts of the world under different environmental settings in italian nvme there has been extensive investigation proving that these soils have a much wider distribution than previously thought but despite these important findings very little is known about their genesis or properties against this background our investigation aims to question the nature of parent material in andic soils in italian nvme we consider this question fundamental for proper understanding of such soils we address the question of the parent material by highlighting similarities dissimilarities between soils and their underlying bedrocks and ascertaining whether soils developed as a result of in situ weathering or because of eolian inputs the study was conducted on 41 soil profiles distributed throughout italian nvme performing an integrated analysis of i grain size distribution gsd by laser granulometry ii end member modelling of obtained gsd iii soil bedrock differences in magnetic susceptibility and iv soil bedrock differences based on the geochemistry of 38 elements the final results from these investigations show that the investigated soils are mainly derived from eolian sediments and that weathering of the underlying bedrock plays a minor role two main types of eolian parent materials seem to coexist in different proportions according to the soil type eolian sediments with a similar composition of the underlying bedrock termed autochthonous loess and eolian sediments of volcanic type pyroclasts autochthonous loess represents the main component of the parent material in the following studied soils aluandic andosols cambisols phaeozems and podzol 67 63 44 and 73 respectively all these soils exhibit low to moderate andic features volcanic type eolian sediments constitute about 90 of the parent material in most andic soils that are silandic andosols but occur in different proportions in most of the investigated soils the nature of soil parent materials surprisingly follows a clear trend with latitude with autochthonous loess characterizing most parent materials in northern italy whilst volcanic sediments form most parent materials in the south in accordance with their latitude other soils exhibit an intermediate behaviour

magnetic susceptibility of early paleozoic and precambrian paleosols abstract paleosols formed by weathering and plant colonization during breaks in eolian deposition of quaternary loesses are marked by enhanced magnetic susceptibility these paleosols can be recognized in the field from their soil structure and soil horizons but the most obvious and diagnostic feature of paleosols are root traces for paleosols of early paleozoic and precambrian age pre dating the evolution of rooted land plants root traces cannot be used as a diagnostic field criterion for recognizing paleosols surficial enhancement of magnetic susceptibility can be useful confirmation that some precambrian and early paleozoic rocks were paleosols unfortunately magnetic susceptibility enhancement of some paleosol profiles is compromised by burial gleization which reduces overall susceptibility values but especially susceptibility at the surface of the profile and produces a marked covariance of magnetic susceptibility with total iron content groundwater and surface water gleization during soil formation also depletes susceptibility over a wide range of iron content to give relatively flat depth functions of susceptibility in contrast well drained soils and paleosols have pronounced surficial susceptibility enhancement over a narrow range of iron content magnetic susceptibility peaks are useful supporting evidence for paleosols entirely red and oxidized but not for paleosols with common green gray reduction spots abundant organic matter iron manganese nodules or other evidence of gleization all known paleozoic and precambrian paleosols have susceptibility an order of magnitude less than in comparable quaternary paleosols and soils so that quaternary magnetic susceptibility climofunctions and chronofunctions cannot yet be applied to paleozoic and precambrian paleosols although their susceptibility values are comparable with those of modern gleyed soils paleozoic and precambrian paleosols maintain a depth function of surficial enhancement of susceptibility as well as red color deeply penetrating cracks and other features of well drained soils burial recrystallization of fine grained magnetite and maghemite may have compromised the magnitude of their susceptibility peaks alternatively they may not have been as biologically active in susceptibility enhancing microbes as modern soils

time dependence of magnetic susceptibility of soil chronosequences on the california coast abstract as the age of the soils in a chronosequence on the california coast increases the difference between the magnetic susceptibility of eluvial and illuvial horizons increases and the residual susceptibility after extraction with citrate bicarbonate dithionite cbd decreases enhanced susceptibility results from the conversion of nonferrimagnetic minerals to secondary ferrimagnetic forms most likely maghemite and the preferential accumulation of inherited and pedogenic magnetic minerals little enhancement occurs for pedons younger than 40 000 yr by 124 000 yr most of the magnetic susceptibility can be attributed to forms soluble in cbd magnetic susceptibility appears to vary systematically over time for three chronosequences from areas with mean annual precipitation ranging from 650 to 1500 mm yr 1 magnetic susceptibility enhancement may be a useful parameter for estimating soil age in certain climates

unexpectedly higher metazoan meiofauna abundances in the kuril kamchatka trench compared to the adjacent abyssal plains abstract we studied meiofauna standing stocks and community structure in the kuril kamchatka trench and its adjacent abyssal plains in the northwestern pacific ocean in general the nematoda were dominant 93 followed by the copepoda 4 nematode abundances ranged from 87 to 96 those of copepods from 2 to 7 the most diverse deployment yielded 17 taxa acari amphipoda annelida bivalvia coelenterata copepoda cumacea gastrotricha isopoda kinorhyncha loricifera nematoda ostracoda priapulida tanaidacea tantulocarida and tardigrada nauplii were also present generally the trench slope and the southernmost deployments had the highest abundances 850 1392 individuals cm 2 the results of non metric multidimensional scaling indicated that these deployments were similar to each other in meiofauna community structure the southernmost deployments were located in a zone of higher particulate organic carbon poc flux g c org m 2 yr 1 whereas the trench slope should have low poc flux due to depth attenuation also poc and abundance were significantly correlated in the abyssal plains this correlation may explain the higher abundances at the southernmost deployments lateral transport was also assumed to explain high meiofauna abundances on the trench slope abundances were generally higher than expected from model results anosim revealed significant differences between the trench slope and the northern abyssal plains between the central abyssal plains and the trench slope between the trench slope and the southern abyssal plains between the central and the southern abyssal plains and between the central and northern deployments the northern and southern abyssal plains did not differ significantly in addition a u test revealed highly significant differences between the trench slope and abyssal deployments the taxa inhabited mostly the upper 0 3 cm of the sediment layer nematoda 80 90 copepoda 88 100 the trench slope and abyssal did not differ in occupancy of the top layer furthermore sediment depth and abundance were strongly correlated but the sediment texture itself and the grain sizes showed only slight correlations with abundance in the trench slope no correlation between sediment texture and abundance was found we suggest that sediment is not the only factor that affects meiofauna abundance in the study area the results of our study were compared with other trench and nontrench studies and in most cases the abundance decreases with depth initially but increases again below a certain depth especially in deep sea trenches below productive waters no generalization can be made however about the depth at which the reversal occurs it depends on the area of investigation and on a mixture of many other factors e g sediment heterogeneity oxygen redox potential proximity to land masses and season

himalaya the northern frontier of east gondwanaland abstract the himalayan province which represents the northern platform of the peninsular india belonging to east gondwanaland was strongly affected by pan african diastrophism 500 25 ma ago this brought to an end the protracted purana cycle of sedimentation throughout the peninsular india and the lesser himalaya and interrupted basin filling in its northern tethyan domain but the sea returned in the early permian along a narrow depression formed due to rifting of the himalayan crust in what is today the southern lesser himalaya in the rift valley was deposited tillites by glaciers of the gondwana continent under grip of refrigeration along with the glacigene conglomerates were emplaced diamictites generated by submarine slides triggered presumably by earthquakes originating from faults delimiting the rift the diamictities are admixed with lava agglomerate and tuff indicating widespread volcanism in the rift valley the rifting culminated in the breaking away of the tibetan part of the himalaya in the late permian and formation of neotethys between the gondwanaland and the cimmerian microcontinent embodying tibet iran and turkey rivers of the northern peninsular india flowed in the northerly directions since the middle proterozoic through early eocene in the late eocene there was a drastic drainage reversal to south and southeast when the himalaya emerged in the northern front of the gondwanaland

rock magnetic properties of a soil developed on an alluvial deposit at buttermilk creek texas usa 1 the evolution of magnetization within a floodplain soil begins with initial deposition of magnetic particles during sedimentation and continues via subsequent alteration and growth of iron bearing compounds by pedogenic and biologic processes measurements of soil magnetic properties capture information about the developmental history of the soil and are a convenient method by which to investigate environmental change and pedogenesis using a range of magnetic measurements a comprehensive scenario for soil development was constructed for floodplain sediments at the debra l friedkin site an important archeological site near buttermilk creek texas floodplain deposits have traditionally been avoided for soil magnetism studies because it is thought that the episodic input of sediment would form soils characterized by discrete sedimentary units rather than a continuous record of pedogenesis we demonstrate that alluvial deposits can sometimes carry a straightforwardly interpretable magnetic signal similar to those typically seen in loess deposits smooth variation of rock magnetic parameters as a function of depth also leads us to conclude that the soil at this site is largely undisturbed and that the age of lithic artifacts found within the soil may be interpreted within stratigraphic context

the tectonic fabric of the ocean basins 1 we present a global community data set of fracture zones fzs discordant zones propagating ridges v shaped structures and extinct ridges digitized from vertical gravity gradient vgg maps we use a new semi automatic fz tracking program to test the precision of our hand digitized traces and find a mean absolute deviation of less than 3 4 km from the raw vgg minima that most clearly delineate each feature and less than 5 4 km from the fz location predicted by fitting model profiles to the vgg data that represent the morphology of the individual fzs these offsets are small considering gravity data only provide an approximation for the underlying basement morphology we further investigate the origin of non fz seafloor fabric by combining published abyssal hill heights computed from gravity anomalies with global half spreading rates a residual abyssal hill height grid with spreading rate effects removed combined with our interpreted tectonic fabric reveals several types of seafloor fabric distinct from typical abyssal hills where discordant zones do not overprint abyssal hill signals residual abyssal hill height anomalies correspond to seafloor that accreted near mantle thermal anomalies or zones of melt depletion our analysis reveals several areas where residual abyssal hill height anomalies reflect pseudo faults and extinct ridges associated with ridge propagation and or microplate formation in the southern pacific ocean

meiofauna abundance and community patterns along a transatlantic transect in the vema fracture zone and in the hadal zone of the puerto rico trench abstract despite the increasing sampling effort that occurred in the deep sea environment during the last decades knowledge about meiofauna ecology in trenches and fracture zones is still scarce based on the lack of this information a longitudinal transect across the vema fracture zone in the north atlantic was sampled to test whether meiofauna abundances differ between northeast and northwest atlantic basins separated by the mid atlantic ridge also for examination of meiofauna depth pattern the puerto rico trench floor its upper trench slope and the western north atlantic abyssal were investigated in this study meiofauna communities were dominated by nematoda 93 and copepoda 4 the highest total abundance of meiofauna was found in the puerto rico trench and the lowest in the western basin we found significant differences between the eastern and western atlantic basins which were potentially caused by differences in current regimes stronger currents observed in the western basin possibly led to the coarser sediment grain size observed in this region and consequently to the lower abundances of the major groups found there besides grain size the total abundance of meiofauna was significantly correlated with total nitrogen total organic carbon and water depth moreover our study reveals a trend of increasing abundance of total meiofauna with increasing water depth in the puerto rico trench also significant differences between the western abyssal and the puerto rico trench were discovered generally the meiofauna abundance in the investigated area decreased from east to west but increased with increasing water depth in the puerto rico trench due to funnelling of organic sediments increased food availability towards deeper regions in trenches could occur and promote higher abundance

thermomechanical evolution of oceanic fracture zones a fracture zone fz model is constructed from existing models of the thermal and mechanical evolution of the oceanic lithosphere as the lithosphere cools by conduction thermal and mechanical boundary layers develop and increase in thickness as age 1 2 surface expressions of this development such as topography and deflection of the vertical i e gravity field are most apparent along major fz s because of the sharp age contrast a simple model including the effects of lateral heat transport but with no elastic layer predicts that variations in seafloor depth and deflection of the vertical will become increasingly smooth and ultimately disappear as the fz ages observations however show that both the fz topography and the deflection of the vertical remain sharp as the fz evolves these two observations as well as the observed asymmetry in deflection of the vertical profiles across the udintsev romanche and mendocino fz s are explained by including a continuous elastic layer in the model the asymmetry in deflection of the vertical is a consequence of elastic thickness variations across the fz modeling also shows that the evolution of the fz topography is extremely sensitive to the initial thermal structure near the ridge transform intersection model geoid steps and their development with age are used to access techniques for measuring geoid offsets across fz s reasonable step estimation techniques will underestimate the overall step amplitude by up to 50 this implies that abnormally thin thermal boundary layers derived from studies of geoid height versus age are not required by the data

magnetic parameters indicate the intensity of chemical weathering developed on igneous rocks in china abstract continental weathering plays a key role in earth surface processes by linking earth s spheres and producing material for cycling previous studies have proposed numerous weathering indices for the evaluation of chemical weathering intensity however few research efforts are devoted to the changes of sediment physical properties during weathering processes and on the correlations between weathering and mineralogical chemical alteration this study investigates mineral transformation and magnetic properties of two weathering profiles developed on granodiorite and basalt in china the notable differences in magnetic properties between the two profiles i e magnetic susceptibility percentage frequency dependent susceptibility fd anhysteretic remanent magnetization arm and saturation isothermal remnant magnetization sirm are ascribed to the combined effects of parent rock lithology and climate conditions on the formation and alteration of magnetic components during weathering pedogenesis parent rock lithology e g fe bearing basalts and relatively fe poor granites determines the initial magnetic susceptibilities warm and humid climate favors rock weathering and thus enhances the magnetic intensity whereas changes in redox conditions lead to inhomogeneous degree of chemical weathering and thus alter the spatial distribution of magnetic minerals this study further suggests that the weathering intensity in geologic profiles can be evaluated by magnetic indicators such as fd and arm sirm based on their positive correlations with the chemical index of alteration cia the research findings may shed new light on the constraints on continental weathering and detrital sediment cycling in the east asian continental margin

the bashkirian fenestella shales and the moscovian chaetetid shales of the tethys himalaya south tibet nepal and india abstract the fenestella shales are a mid carboniferous marker unit which has long been described from classic localities of the nw himalaya kashmir spiti correlative shaly units have recently been traced in central nepal and as far as south tibet where they yielded varied brachiopod assemblages indicative of bashkirian age a second distinct interval of black shales characterized by the abundance of chaetetids and directly underlying the widespread gondwanan diamictites has been dated as moscovian in spiti and represents the youngest fossiliferous horizon hitherto identified in the upper carboniferous of the tethys himalaya the chaetetid shales are recognized also in manang whereas in south tibet the stratigraphic framework still needs improved definition these major fossiliferous black shale units marking repeated transgressive events in the middle part of the himalayan rift sequence have not only major stratigraphic significance but also represent a fundamental landmark in palaeogeographic and palaeoclimatic reconstructions of northern gondwana with the onset of continental rifting arid tropical climates at the close of the tournaisian were replaced by temperate humid conditions in the visean serpukhovian when diamictites were deposited in south tibet after this first cooling stage the fenestella shales mark a widespread transgression at the very beginning of the late carboniferous coupled with reduced tectonic activity and temperate to temperate warm climates after renewed tectonic activity during a second cooling episode marked by local deposition of diamictites in central nepal the chaetetid shales represent another major transgression in the moscovian shortly preceding the final and most intense cooling event marked by deposition of glacio marine diamictites in the whole tethys himalaya from kashmir to south tibet during the latest carboniferous earliest permian two fossiliferous horizons containing very similar brachiopod faunas of early late carboniferous age have recently been found also in north karakorum at lower southern latitudes where climatic conditions always remained temperate and there is no trace of upper palaeozoic glacial deposits or ice rafted debris

a proposed biogeography of the deep ocean floor abstract while there are many generalized schemes representing the biogeographic distribution of life in the deep sea reviewed here a comprehensive analysis has not been undertaken since vinogradova 1979 vinogradova 1997 for the abyssal and belyaev 1989 for the hadal the purpose of this paper is to propose global biogeographic provinces for the lower bathyal and abyssal benthos 800 m depths in order to aid high seas management efforts biological samples from these depths are sparse so delineation of biogeographic provinces was initially hypothesized using oceanographic proxies and examined with documented locations of select benthic marine species these biogeographic provinces were first developed in 2009 via an expert consultation workshop to delineate biogeographic provinces in offshore regions the global open ocean and deep sea goods classification we have refined the goods deep sea classification by incorporating additional high resolution hydrographic and organic matter flux data for the seafloor water mass characteristics temperature and salinity and particulate organic flux to the seafloor were the strongest determinants in the final delineation of provincial boundaries this process resulted in the delineation of 14 lower bathyal and 14 abyssal provinces the bathyal and abyssal classifications presented here should be used with other management tools and analyses e g predictive habitat modeling seamount classifications etc to help determine where marine protected areas should be placed and to minimize the negative impacts of commercial activities in the high seas

problems in applying preservation facies and sequence models to sinian neoproterozoic glacial sequences in australia and asia abstract the sinian 800 530 ma is an extraordinary period of earth history characterized by the transition from simple to complex multicellular organisms and by extreme variations in climate eustasy and possibly tectonics understanding sinian stratigraphy may help interpret the co evolution of life and environment during the period though sinian successions are poorly dated and difficult to correlate preservation facies and sequence models based on mesozoic recent successions may be used to interpret them preservation models based on basin subsidence permit estimates of how thick and complete successions can be in different tectonic settings and how long it took for them to be deposited facies models for rift craton shelf slope and basin environments help in identification of these different tectonic settings sequence models facilitate interpretation of the interplay of tectonic subsidence eustasy rates of sedimentation and climate such models applied to the sinian successions of australia and asia indicate the following great shallowing upwards megacycles occur in sinian successions and each ends with regional glaciations deep rift basins formed around 850 800 ma preserve the oldest megacycles but these basins soon were filled with rapidly deposited glaciogenic sediments relatively complete sequences are found only in deep basins subject to repeated rifting cratons and shallow shelves preserve only the youngest megacycles older deposits have been removed by younger glacial advances deep shelves and slopes preserve one to three megacycles depending on the timing of the start of passive margin subsidence megasequences can be correlated based on limited radiometric dating and inferred regional distribution of unique rock types but these sequences are not developed to the same extent in all blocks problems in correlating the four great megacycles recognized elsewhere with those of asia will persist until the requisite facies analysis and u pb dating of interbedded volcanics are done

comparing mineral magnetic properties of sediments in two reservoirs in strongly and mildly eroded regions on the guizhou plateau southwest china a tool for inferring differences in sediment sources and soil erosion shibanqiao reservoir 0 24 km 2 and xiaohe reservoir 0 28 km 2 have catchments of 6 00 km 2 and 22 69 km 2 respectively they essentially represent strongly eroded shibanqiao and mildly eroded xiaohe regions in guizhou plateau southwestern china sediment cores were retrieved from the two reservoirs and soils were also sampled from their catchments mineral magnetic measurements were performed on the sediments and soils and the particle size analysis of selected sediment cores and soil profiles were also made sirm versus chi if was used to compare sediment and soil samples in addition correlations between percentages of different particle size fractions and magnetic parameters ratios of sediment samples were also checked these results revealed differences in sediment sources and soil erosion in these two representative catchments the sediments in shibanqiao reservoir are derived from both the topsoil and subsoil when erosion is relatively weak it is limited to the topsoil and preferentially transports the relatively finer magnetic grains into the reservoir which may imply rain splash and or sheet erosion in this relatively steep catchment stronger erosional forces are capable of not only moving relatively coarser ferrimagnetic grains from the topsoil but also incising the subsoil and moving anti ferromagnetic minerals into the reservoir which seems to hint at not only sheet wash but also rill and gully erosion as there are no stable streams nor channel networks developed in this mountainous catchment contributions from river bank erosion to sediment yield are almost negligible the sediments in xiaohe reservoir which has a lower relief are predominately derived from topsoil erosion here erosion is concentrated to the topsoil and preferentially transports the relatively fine magnetic grains into the reservoir when erosional forces are weak however even when erosional forces increase in this relatively flat catchment erosion is still restricted to the topsoil thus relatively coarser ferrimagnetic grains from the topsoil are transported to the reservoir but the subsoil remains undisturbed and there are no significant changes in the proportion of anti ferromagnetic minerals in the sediments consequently only sheet washing occurs even when erosion is intensifying in this hilly plain catchment in general the more effective erosion in the shibanqiao catchment is probably due to its steeper topography than xiaohe catchment although higher and more seasonal rainfalls and lower percentages of woodlands may also contribute to the differences in susceptibility to erosional forces c 2011 elsevier b v all rights reserved less

mapping soil magnetic properties in bosnia and herzegovina for landmine clearance operations electromagnetic properties of soils have negative impacts on metal detector performance during landmine clearance operations in particular topsoils with high concentrations of pedogenic viscous superparamagnetic minerals magnetite maghemite as shown by high values of magnetic susceptibility and frequency dependent susceptibility limit the detector capability of identifying buried landmines thus a priori knowledge of the spatial extent of soils that may be problematic for landmine detection would aid strategic planning of clearance operations and ensure appropriate equipment is deployed here we compare two approaches for estimating the broad magnetic properties of soils in bosnia and herzegovina 1 an analogue approach using data for magnetic susceptibility and frequency dependent susceptibility available for soil types from other temperate and mediterranean regions 2 magnetic measurements of a stratified sample of soil samples taken from the bosnian national soil archive the national soil magnetic maps produced estimate that the area of land inferred as problematic for metal detectors is 4 and 30 according to the analogue and measurement methods respectively combining soil type with soil parent material and climate explains the spatial variability of soil magnetic properties in terms of mechanisms of secondary ferrimagnetic mineral production and accumulation the resulting maps indicate that the magnetic properties of dominant soils in northern bosnia tend to be unproblematic for detectors while in central bosnia there is likely to be moderate detector interference however there is a high likelihood of dominant soils affecting detectors in southern and western bosnia and herzegovina equivalent to 30 of the total land area the mapped outputs of susceptibility and frequency dependent susceptibility provide demining end users with an indication of the likelihood of encountering problem soils in areas selected for clearance operations

factors affecting the magnetic susceptibility of a loess soil sequence barton county kansas usa abstract to interpret climatic signatures from magnetic susceptibility ms in the barton county loess soil sequence central kansas we tested the influence of particle size and carbonate concentration on magnetic susceptibility first sand silt and clay were separated and ms was then measured on each of the three size fractions to assess the influence of chemical treatments and carbonate on ms signals the chemical agents used to remove carbonate organic matter and free iron oxides were applied to another set of samples and ms was measured before and after each of the treatments the results show that the bulk ms differentiates among stratigraphic units but the environmental interpretation is far from straightforward soils have stronger ms signals than the loess units in the upper portion while the carbonate rich soils have weaker ms signals in the lower portion due to the ms dilution effect of carbonate sand ms peaks in bignell loess peoria loess and ll1 may suggest that in loess units fewer sand sized magnetic minerals were changed by weathering processes into clay sized magnetic minerals than in soils a low bulk ms at the bottom of the reddish pedocomplex to the bottom of ls 1 is attributable to a combination of a high sand content and a high carbonate concentration the silt ms peak in the barton sand might have been derived from the parent materials comparing with mineralogic and chemical indices clay ms might be closer to being a proxy of weathering intensity although clay ms dominates the bulk ms signals silt ms and sand ms affect the bulk ms signals in two ways 1 changes in the percentages of silt and sand and 2 mineralogical variations in silt ms and sand ms from one stratigraphic unit to another this study demonstrates that 40 of the variation in the bulk ms is accounted for by the clay ms and 56 of the variation by the silt ms and clay ms together after adding the sand ms 66 of the variation is accounted for if diamagnetic carbonate is taken into consideration 76 of the variation in bulk ms is accounted for by the ms of the three size fractions and the ms dilute effect of carbonate

geochemical normalization of magnetic susceptibility for investigation of floodplain sediments magnetic susceptibility ms is commonly used as a proxy for industrial pollution in natural sediments or as a proxy for the percentage of detrital components in peat or carbonates the ms may also reflect the geology of the sediment source and post depositional processes in sediments such as soil development the aim of our research was to test the usefulness of fe normalized mass specific ms and ti normalized fe in a study of floodplain sediments we sampled 27 floodplain sediment cores from several geologically different catchments throughout the czech republic analysed their fe and ti concentrations using x ray fluorescence spectroscopy and determined their to decipher sediment grain size dependence and possible magnetic enrichment background functions for were constructed using similar approach as that used for geochemical background functions of the risk element concentrations with fe concentrations as an independent variable it provides a mechanism to calculate of sediments as it would be pristine i e without post depositional changes and pollution sediments derived from mafic source rocks had fe larger by two orders of magnitude than sediments derived from felsic rocks sediments derived from mafic source rocks also exhibit lower mean fe ti ratio in pristine sediment strata than the average upper continental crust the magnetic carriers inherited from mafic rocks are stepwise destroyed by pedogenesis in the floodplains and thus slowly approach of sediments derived from felsic rocks gleying processes may change fe fe ti ratio allows identifying a past action of those post depositional processes

magnetostratigraphy of the qiliting section se china and its implication for geochronology of the red soil sequences in southern china summary the red soil sequences in southern and southeastern china provide important terrestrial archives of palaeoclimate and palaeoenvironment and are important sources of palaeolithic settlements and therefore early human occupation here we present detailed palaeomagnetic investigation coupled with mineral magnetic and petrographic analyses of a red soil sequence at qiliting southeastern china the sediments contain both strongly magnetic minerals such as maghemite and magnetite and weakly magnetic minerals such as haematite and possibly goethite maghemite and haematite were identified as the main carriers of the natural remnant magnetisations only haematite dominates the characteristic remnant magnetisations palaeomagnetic findings suggest that the qiliting sedimentary sequence recorded the early brunhes chron and the late matuyama chron including the jaramillo subchron our finding coupled with previously published magnetostratigraphy establishes that the red soil sequences in southern china began to accumulate no later than the jaramillo age i e 1 0 ma it is further suggested that the capabilities of recording magnetic polarity stratigraphy in chinese red soil sequences are variable between areas because of different climate regimes

lithostratigraphic correlation of blaini formation late proterozoic lesser himalaya india with other late proterozoic tillite sequences the blaini formation of the lesser himalaya has long been considered permo carboniferous in age on simple lithological correlation with gondwana tillites in southern india rare and non repeatable finds of fossils from the type area were thought to confirm this recently lower cambrian faunas have been recorded from the overlying tal and krol formations and possible metazoan trails recorded from the blaini itself in addition the blaini formation is even on a lithostratigraphic comparison much more like other late proterozoic glacial sequences the term blaini formation should only be used for rocks of the type area not for widely scattered glacial deposits which may or may not be correlatable with the type section the persistent belief in the paleozoic age of the blaini and adjacent formations has for long retarded unterstanding of lesser himalaya stratigraphy and tectonics

early carboniferous onset of gondwanian glaciation and neo tethyan rifting in south tibet at least four diamictite bearing intervals of early carboniferous age containing faceted pebbles trapezoidal cobbles and boulders up to 1000 m3 in volume have been recognized and traced for over 200 km along the tethys himalayan zone of south tibet from east of everest to west of shishapangma these largely glacio marine sediments intercalated within the rakyang formation which overlies lower tournaisian limestones and underlies lower bashkirian black shales were deposited during the visean to serpukhovian shore ice thus began to form in this region of northern gondwana several tens of million years earlier than previously thought this glacial event occurred at middle southern latitudes and was triggered by basin inversion and tectonic uplift in the first stages of neo tethyan rifting as documented by the close association of diamictites with olistoliths and olistostromes in lower carboniferous units after a transgressive interglacial episode in the bashkirian a much more widespread glaciation occurred in the latest carboniferous and was shortly followed by continental break up and opening of neo tethys in the late early permian

soil development in a quaternary fluvio lacustrine paleosol sequence in southern italy abstract the aim of this paper is to enrich our knowledge of an important paleosol succession located in bojano basin of the southern apennines italy with new pedological geochemical and magnetic data the studied area consists of alluvial and fluvial lacustrine sequences 160 m dating from the middle pleistocene 0 5 ma the study area shows the presence of recent soil consisting of well developed andosols rs and several clastic sedimentary levels alternating with four layers solum i ii iii and iv of paleosols soil and paleosols were analyzed by laser grain size distribution gsd diffuse reflectance spectroscopy drs trace elements and magnetic properties in order to evaluate the relative contributions of pedogenic and detrital components results showed that the finest pedogenic ferrimagnetic grains exhibit two trends with respect to the degree of pedogenesis indicate two different pedoclimate formations the paleosol sequence consists of highly weathered vertisols solum i and iv and of less weathered entisols solum ii iii the recent soil andosol has a strong bimodal distribution formed mostly by coarse silt size particles related to the volcanic parent material solum i showed a sharp unimodal clay gsd while solum iii and iv were composed of bimodal gsd with high percentages of fine silt size particles on the basis of the trace element content and gt fd ratio all solum i ii iii iv exhibited low weathering pedogenesis compared with rs and negligible contribution to the magnetic properties of the coarse fractions this occurs in vertisols which developed under humid temperate climates solum i and siv and formed below the layer of neapolitan yellow tuff developed after 12 15 ka bp in solum ii iii the finest sedimentary levels the low rate of pedogenesis could have developed under more cold climatic conditions after the last eruption campanian ignimbrite 39 ka in the late pleistocene

tracing movements of topsoil by magnetic measurements two case studies an array of magnetic measurements is used to trace the occurrence of magnetically enhanced topsoil in two different environmental settings the first is a cultivated slope section where the results confirm that movements of topsoil have occurred but that identification of specific erosional processes is problematic the second is a lake catchment system where measurements on soils and sediments allow a partial reconstruction of soil movements from different sources over the last 200 y the study highlights both the need to analyse the magnetic mineralogies of different particle size fractions and the difficulties that may be encountered in trying to discriminate between topsoil and subsoil material on the basis of demagnetization parameters alone

mineral magnetic properties of a weathering sequence of soils derived from basalt in eastern china abstract the magnetic properties and magnetic mineralogy of a weathering sequence of soils developed on basalt parent material from eastern china were studied by rock magnetism x ray diffraction and soil chemical analyses to establish the connection between mineral magnetic properties and pedogenic development in a subtropical region the magnetic susceptibility of soils formed on basalt varied greatly and did not increase with the degree of pedogenic development the frequency dependent susceptibility fd values of soils ranged from 1 0 to 11 1 and increased with the pedogenic development highly significant linear relationship was found between the frequency dependent susceptibility and the fed content r2 0 683 and fed fet ratio r2 0 780 in soils indicating that pedogenic sp ferrimagnetic grains were associated with enrichment of the secondary iron oxide minerals in the weathering process of soil rock magnetism analysis showed that the major magnetic carriers in the weakly weathered soil profiles are magnetite and or maghemite and the highly developed soil profiles are generally enriched in magnetite maghemite grains of pedogenic origin and the magnetically hard haematite indicating that the magnetic component was transformed from a ferrimagnetic phase magnetite to antiferromagnetic phase hematite during pedogenic development results indicated that some of the magnetic parameters of soils in this case fd can be useful for pedogenic comparisons and age correlations in the weathering sequence of soil it is thus suggested that multiparameter rock magnetic investigations represent a more powerful approach for pedogenesis

weathering characteristics of interflow volcanic boles from mandla lobe eastern deccan volcanic province abstract the deccan volcanism straddling the cretaceous paleogene boundary resulted into one of the most extensive continental flood basalts in the western and central peninsular india the interflow sedimentary units boles often cited as paleosols are the rare archives of paleoenvironmental conditions existed during successive lava flows a debate on the origin of boles as true paleosols exists therefore in order to trace out regional extent of such conditions pedogenic non pedogenic in the context of their paleoenvironmental significance during the deccan volcanism we studied here mineral magnetic characteristics of 36 color differentiated bole beds from the mandla lobe in the eastern deccan volcanic province edvp classified into four types gray yellow brown and red based on their munsell notations the gray yellow and brown boles show dominantly ferrimagnetic composition chiefly magnetite and titanomagnetite while red boles characterize mixed ferri and antiferromagnetic mainly hematite mineralogy the granulometric domain parameters suggest larger single domain sd and the multidomain md ferrimagnets in the majority of cases whereas superparamagnetic sp particles with frequency dependent susceptibility fd 2 6 to 20 3 10 8 m 3 kg 1 are limited to the few red and brown boles only the significant presence of primary parent magnetic minerals i e coarse sd md titanomagnetite and magnetite in the majority of boles depict incipient to moderate weathering owing to limited time intervals during successive eruptions the combination of hematite and sp particles present only in the few red and brown boles depicts baking effect rather than pedogenesis the comparison of magnetic properties of boles from edvp and western deccan volcanic province wdvp shows significant differences in the concentration of sp ferrimagnetic particles and hematite attributed to variable weathering intensity duration and heating related alterations from the upper flows both edvp and wdvp boles indicate similar first order paleoenvironmental conditions without any major pedogenesis that can be regionally correlated

palaeoclimatic and sedimentary history from magnetic susceptibility of loess in china the magnetostratigraphic age of the oldest loess sediments in the central chinese loess plateau investigated so far has recently been placed at ca 2 4 million years b p thus glaciations in central asia which are believed to provide the detritus for the formation of chinese loess commenced at the same time as the first ice rafted debris sank into the ocean basins of the northern hemisphere shackleton et al 1984 lithologic palaeontologic geochemical and especially rock magnetic variations throughout the loess column are indicative of palaeoclimatic fluctuations during loess deposition the variations of magnetic low field susceptibility in loess closely resemble those of the marine oxygen isotope record shackleton and opdyke 1976 and establish for the first time a continuous record of the pleistocene glacial and interglacial stages in a continental section spectral analysis of the rock magnetic time series indicates slow apparent sedimentation during interglacial periods which are characterized mainly by calcium dissolution and related compaction of the soils variable aeolic sediment influx as well as erosion and or polygenetic soil formation may also strongly influence the sedimentary history

fracture zones in the north atlantic from combined geosat and seasat data we present a new tectonic fabric map of the northern and central north atlantic ocean floor from 10 s to 66 n based on combined geosat and seasat altimetry data short wavelength vertical gravity along track was derived by hilbert transforming and high pass filtering geosat and seasat deflection of the vertical profiles the along track gravity data were used in conjunction with magnetic anomaly data to locate a large number of fracture zones as well as extinct spreading ridges and v shaped structures we traced many fracture zones more continuously and closer to adjacent continental margins than was previously possible we also mapped a number of unnamed fracture zones and fracture zone segments many of which were previously uncharted we have evaluated the agreement between the mapped fracture zones and synthetic flow lines as predicted from recent plate models for the opening of the north central north and south atlantic most fracture zones in this area correlate quite well with synthetic flow lines supporting the proposition that geosat seasat altimetry data serve as a useful tool to map fracture zones where insufficient bathymetric data are available many fracture zones including some small offset fracture zones in the central north atlantic have been stable and follow tectonic flow lines for tens of millions of years however many other fracture zones do not reflect a railroad track pattern of plate motions the geometry of many small and medium offset fracture zones indicates that the ridge axis discontinuities that produce them can migrate along the ridge causing off axis traces that deviate from tectonic flow lines velocity space diagrams constructed using a recent relative and absolute present day plate motion model indicate that some low angle v shaped troughs and ridges are likely formed by migration of the plate boundary relative to a mesospheric reference frame other low angle v shaped structures reflect slow migrations oscillations of small offset ridge axis discontinuities that are distinct from both tectonic flow lines and v shapes reflecting absolute plate motions high angle v shaped structures are the result of fast migrating ridge axis discontinuities propagating rifts

soil magnetic susceptibility and its relationship with naturally occurring processes and soil attributes in pedosphere in a tropical environment abstract soil magnetic susceptibility has potential to be used as a pedoenvironmental indicator from which mineralogy pedogeochemical pedogeomorphological and pedogenic processes can be inferred it can be used in pedosphere studies as an auxiliary information for appropriate and sustainable soil use and management this research aimed to analyze how pedogenesis and geochemical processes affect the and some of its attributes as well as its potential use in discriminating soil great groups following the digital soil mapping approach the study area is located in sao paulo state brazil soil samples were collected for physical chemical analysis from 79 locations 0 20 cm depth at these sites magnetic susceptibility was measured with a portable field instrument and analyzed in terms of geology relief and soil class the results showed that geology strongly affects mainly in diabase derived soils followed by metamorphosed siltstone and siltstone in fluvial sediments the exhibits different behaviors due to different sediments deposited by the capivari river in less evolved soils such as cambisols lithology is a more important contributor to than pedogenesis in more evolved soils pedogenesis increases whereas argilluviation ferralitization reduces it the values did not decrease significantly or even increase downslope due to the presence of diabase on the lower parts differences in where observed between diabase bedrock located in different parts of the study area indicating more of an influence by geomorphic processes rather than lithology with respect to soil attributes positive correlations between and base saturation cation exchange capacity organic matter and iron and clay content were found whereas a negative correlation was found between and sand content the correlates with changes in lithology and soil class demonstrating its application as a potential tool for the discrimination of soil great groups and digital soil mapping

effect of the 2011 tohoku earthquake on deep sea meiofaunal assemblages inhabiting the landward slope of the japan trench abstract meiofaunal assemblages inhabiting the landward slope of the japan trench water depth 120 5600 m were examined 4 5 months and 1 5 years after the 2011 tohoku earthquake off sanriku miyagi prefecture northeast japan two key parameters were compared before 24 30 years and after 4 5 months in 2011 and 1 5 years in 2012 the earthquake a the bathymetric pattern and b the vertical distribution of meiofauna in the sediments differences in meiofaunal densities and associated bathymetric patterns were not detected before and after the earthquake however the vertical profiles of meiofauna in the sediments differed at some stations the highest meiofaunal densities occurred in the subsurface layers in 2011 at some stations with these subsurface peaks being no longer present in 2012 at these stations the assemblage structure at the higher taxon level differed between 2011 and 2012 with copepod density increasing in 2012 therefore copepod abundance appeared to decrease because of the effect of earthquake related events e g rapid sedimentation induced by the turbidity current these changes in meiofaunal vertical profiles and assemblage structures detected after the earthquake were probably caused by an increase in organic matter content in the topmost layers these results indicate that major disturbances to deep sea sediments mainly influenced the vertical distribution and assemblage structure of meiofauna after the 2011 tohoku earthquake whereas meiofaunal densities remained similar or quickly recovered within 4 5 months of the event

mineral magnetism to probe into the nature of palaeomagnetic signals of subtropical red soil sequences in southern china summary magnetic polarity stratigraphy has proved to be useful in dating of both marine and terrestrial sedimentary sequences over the world however the reliability of magnetostratigraphic results of red soil sequences in subtropical southern china has been found to be variable in different regions to probe into the capabilities of recording magnetic polarity stratigraphy in the red soils three red soil sequences have been selected for detailed mineral magnetic petrographic and or palaeomagnetic analyses these include the xuancheng and qiliting sequences which are located in the lower reaches of the yangtze river and the damei sequence in the bose basin near the tropic of cancer palaeomagnetic results indicate that the xuancheng sequence has recorded the brunhes chron and the late matuyama chron including a short interval probably representing the santa rosa geomagnetic event the xuancheng and qiliting sequences have faithfully recorded the palaeogeomagnetic field behaviour while the damei sequence has failed detailed mineral magnetic and petrographic measurements suggest that four magnetic minerals magnetite maghemite haematite and goethite are contained in the three studied sequences but the characteristic remanent magnetization chrm carriers are different for the xuancheng and qiliting samples the chrm carriers are magnetite and haematite which are all of detrital origin however the chrms of damei samples are carried by pedogenic haematite with an unblocking temperature tb of about 630 640 c which has overprinted the primary remanence of the damei red soil deposits this pedogenic haematite is mainly produced by chemical weathering which is commonly intensified by the climate of high temperature and rainfall it further suggests that climatic conditions have a great effect on the nature of palaeomagnetic signals of the red soil sequences in addition the red pigment components in the red soils may be used to indicate the degree of remagnetization