a large landslide on the urban fringe of metropolitan phoenix arizona a granitic rock avalanche one of the largest quaternary landslides in arizona outside the grand canyon with a volume of approximately 5 25 m m 3 and a width a little under 0 5 km ran 1 km from the eastern mcdowell mountains with lateral levees and pressure ridges the rock avalanche deposit displays many features found on classic sturzstroms failure occurred along a major joint plane paralleling the slope with a dip of 448 when a major base level lowering event in the salt river system would have undermined the base of the failed slope and probably during a period of more moisture than normally available in the present day arid climate failure at the subsurface weathering front highlights the importance of the dramatic permeability change between grussified regolith and relatively fresh bedrock rock varnish microlaminations vmls dating in concert with other geomorphic evidence suggests that the rock avalanche deposit is slightly older than 500 ka the rock vanish results also have important implications for sampling strategies designed to use cosmogenic nuclide to date quaternary landslide deposits discovery of a large landslide in close proximity to the extending urban fringe of metropolitan phoenix argues for a more careful analysis of landslide hazards in the region especially where rapid development excavates bedrock at the base of steep mountain slopes and where the subsurface weathering front is near the surface d 2004 elsevier b v all rights reserved

erosion rates over millennial and decadal timescales at caspar creek and redwood creek northern california coast ranges comparing millennial scale denudation rates from cosmogenic nuclides with decadal scale sediment yields can shed light on erosional processes and on the effects of land use on sediment delivery to streams detailed measurements of sediment fluxes in the northern california coast ranges at caspar creek and redwood creek have provided estimates of physical erosion rates since 1963 and 1971 respectively we used cosmogenic 10 be to measure

organic carbon flux controls the morphology of magnetofossils in marine sediments magnetotactic bacteria produce chains of magnetite crystals within a cell bacterial magnetites have characteristic morphologies and sizes that are strictly biologically controlled we examined morphologies of fossil bacterial magnetites magnetofossils preserved in pacific deep sea sediments and their relations to organic carbon fluxes isotropic crystals dominate magnetofossils in sediments in relatively oxidized conditions and anisotropic crystals predominate in more reduced conditions our finding has important implications for biomineralization processes and demonstrates the potential of magnetofossil morphology as a paleoenvironmental indicator

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

a 14 000 year sediment yield record from western germany based on annually laminated lake sediments the reconstruction of sediment yield data for the catchment of lake holzmaar 205 8 ha in the eifel mountains western germany is based on high resolution geochemical and physical analyses of an absolutely dated sediment record this technique provides flux rates of allochthonous minerogenic deposition for the last 13 840 years the pleistocene holocene transition is characterized by instable soils and vegetation caused by adjustment of the catchment to interglacial climatic conditions these instabilities are the reason for elevated mean sediment yields in the catchment of 16 t km 2 yr 1 until 9800 cal bp during most of the holocene erosive processes are insignificant and sediment yields are very low 1 5 t km 2 yr 1 since humans cleared the forests for agriculture and early industrial purposes the natural environment has been disturbed and sediment yields increased to mean values of 14 t km 2 yr 1 during the last 2750 years comparisons of reconstructions from the eifel area with similar data from southern sweden and with measured data from lakes reservoirs and monitoring sites suggest that quantitative reconstructions based on lake holzmaar sediments may be regarded as reliable despite uncertainties related to the methods of reconstruction applied

mind the gap towards a biogenic magnetite palaeoenvironmental proxy through an extensive finite element micromagnetic simulation abstract magnetotactic bacteria mtb preserved in sediments magnetofossils are highly sensitive to environmental and climatic forcing and can therefore be used as an easy to measure palaeo environment proxy it is known that magnetofossils occur with various morphologies each with its own particular magnetic signature we present the first systematic extensive micromagnetic study relating magnetosome chain morphology to their hysteresis parameters we modelled more than 450 different intact magnetosome chains in the finite element micromagnetic modelling software merrill relating the morphology magnetosome size elongation intra chain spacing and chain length to the magnetic parameters of coercivity coercivity of remanence and saturation magnetization and analyzing domain states and switching modes it is shown that magnetic properties are far dominated by the intra chain spacing however analysis of a large set of published tem images of different mtb strains shows a strong correlation between intra chain spacing and grain size this correlation can in principle be used to infer mtb morphology purely from magnetic measurements providing a framework to use biogenic magnetite as a sensitive palaeo environment proxy additionally it is found that mtb carefully control intra chain spacing during magnetosome synthesis to maximize saturation remanence as well as magnetic stability

potbellies wasp waists and superparamagnetism in magnetic hysteresis because the response of a magnetic substance to an applied field depends strongly on the physical properties of the material much can be learned by monitoring that response through what is known as a magnetic hysteresis loop the measurements are rapid and quickly becoming part of the standard set of tools supporting paleomagnetic research yet the interpretation of hysteresis loops is not simple it has become apparent that although classic single domain pseudo single domain and multidomain loops described in textbooks occur in natural samples loops are frequently distorted having constricted middles wasp waisted loops or spreading middles and slouching shoulders potbellies such complicated loops are often interpreted in oversimplified ways leading to erroneous conclusions the physics of the problem have been understood for nearly half a century yet numerical simulations appropriate to geological materials are almost unavailable in this paper we discuss results of numerical simulations using the simplest of systems the single domain superparamagnetic sd sp system examination of the synthetic hysteresis loops leads to the following observations 1 wasp waisting and potbellies can easily be generated from populations of sd and sp grains 2 wasp waisting requires an sp contribution that saturates quickly resulting in a steep initial slope and potbellies require low initial slopes the sp contribution approaching saturation at higher fields the approach to saturation is dependent on volume hence the cube of grain diameter therefore there is a very strong dependence of hysteresis loop shape on the assumed threshold size 3 we were unable to generate potbellies using an sp sd threshold size as large as 30 nm and wasp waists cannot be generated using a threshold size as small as 8 nm the occurrence of both potbellies and wasp waists in natural samples is consistent with a room temperature threshold size of some 15 nm 5 4 simulations using a threshold size of 15 20 nm with populations dominated by sp grain sizes that is with a small number of sd grains produce synthetic hysteresis loops consistent with measured hysteresis loops and transmission electron microscopic observations from submarine basaltic glass 5 simulations and measurements using two populations with distinct coercivity spectra can also generate wasp waisted loops a relatively straightforward analysis of the resulting loops can distinguish the latter case from wasp waisting resulting from sp sd behavior

an appalachian amazon magnetofossil evidence for the development of a tropical river like system in the mid atlantic united states during the paleocene eocene thermal maximum on the mid atlantic coastal plain of the united states paleocene sands and silts are replaced during the paleocene eocene thermal maximum petm by the kaolinite rich marlboro clay the clay preserves abundant magnetite produced by magnetotactic bacteria and novel presumptively eukaryotic iron biomineralizing microorganisms using ferromagnetic resonance spectroscopy and electron microscopy we map the magnetofossil distribution in the context of stratigraphy and carbon isotope data and identify three magnetic facies in the clay one characterized by a mix of detrital particles and magnetofossils a second with a higher magnetofossil to detrital ratio and a third with only transient magnetofossils the distribution of these facies suggests that suboxic conditions promoting magnetofossil production and preservation occurred throughout inner middle neritic sediments of the salisbury embayment but extended only transiently to outer neritic sediments and the flanks of the embayment such a distribution is consistent with the development of a system resembling a modern tropical river dominated shelf

characterization of hematite α fe2o3 goethite α feooh greigite fe3s4 and pyrrhotite fe7s8 using first order reversal curve diagrams 1 first order reversal curve forc diagrams have become a standard tool in rock magnetism yet magnetite is the only magnetic mineral that is well characterized using forc diagrams we present forc diagrams for predominantly single domain sd synthetic aluminous hematite a fe2 xalxo3 and goethite a feal ooh and natural greigite fe3s4 and pyrrhotite fe7s8 to constrain interpretation of forc diagrams from natural samples hematite and goethite have low spontaneous magnetizations and negligible magnetic interactions while greigite and pyrrhotite have higher spontaneous magnetizations and can have strong magnetic interactions the coercivity of hematite systematically increases with al content only for samples produced using the same synthesis method but it is variable for samples produced with different methods even for similar al content this precludes use of magnetic coercivity alone to quantify the al content of natural hematites goethite has much higher coercivity than hematite for all measured samples sd and superparamagnetic sp behavior is common in natural greigite samples with peak coercivities ranging from

the detection of magnetotactic bacteria and magnetofossils by means of magnetic anisotropy an important characteristic of magnetotactic bacteria mtb is the anisotropy of one dimensionally aligned magnetite particles this paper introduces the use of ferromagnetic resonance spectroscopy fmr at two different frequencies to compare the anisotropic properties of magnetite chains of cultured intact mtb with those of lake sediments of holocene age in order to detect magnetofossils and to characterize their preservation in a geological system magnetite chains of intact mtb exhibit a predominantly uniaxial anisotropy in the lake sediments where diagenetic processes disintegrate the chains and diminish their uniaxiality magnetite chains or chain fragments and dissociated bulk magnetite particles differ in their anisotropy properties the two groups of assembly can be distinguished by empirical spectral separation of the fmr signal this straightforward use of the characteristics of magnetic anisotropy provides a way to detect magnetofossils experimentally thus allowing a better insight into microbial ecology during earth s history

geomagnetic field intensity changes in sweden between 9000 and 450 cal bp extending the record of archaeomagnetic jerks by means of lake sediments and the pseudo thellier technique the pseudo thellier technique was applied to recover relative palaeointensity pt rpi estimates from four piston cores retrieved from a holocene lake sediment sequence in the province of smaland central southern sweden a time depth model between 11 000 and 450 cal bp was based on a combination of calibrated radiocarbon ages and the ages of established palaeomagnetic secular variation psv features that were transferred from a varve dated regional master curve in fennoscandia significant peaks in geomagnetic field intensity occurred at similar to8400 similar to6400 3900 and 2800 cal bp the maximum field intensity at 2800 cal bp was associated with the most rapid change in the direction of the geomagnetic vector while the high resolution sedimentary data show that significant century scale increases and decreases in relative field intensity between 4000 and 2000 cal bp were associated with abrupt changes jerks in the direction of the geomagnetic vector archaeomagnetic jerks younger than 2000 years were not reproduced in this multiple sediment core study on the other hand the pt rpi reconstructions display century to millennial scale trends between 5000 and 450 cal bp that are coherent with archaeomagnetic data sets from western europe and central asia this agreement indicates that palaeointensity may be used as a relative dating technique across this region fennoscandian psv and rpi records for the earlier holocene do not show the same rapid style of vector movement which suggests that northern europe has been affected by a more turbulent geodynamo since similar to4000 cal bp c 2004 elsevier b v all rights reserved less

sediment output and effective discharge in two small high mountain catchments in the bavarian alps germany abstract sediment output solid and dissolved load from two small alpine rivers partnach and lahnenwiesgraben in the bavarian alps was measured during three summer field seasons from 2001 2003 there is high spatial variability of sediment output between the catchments and a high temporal variability between observation periods sediment transport in the partnach river reintal is dominated by solute load whereas the lahnenwiesgraben river transports a much greater proportion of solid load this difference can mainly be explained by the different lithologies of the systems the reintal catchment is dominated by massive triassic limestone in the lahnenwiesgraben catchment in addition to limestones unconsolidated rocks marls and mudstone layers are significant furthermore large rockslide dams in the partnach valley isolate large parts of the reintal catchment from solid load output the components of fluvial sediment transport were where possible calculated by using flow duration curves and rating curve techniques in the lahnenwiesgraben event specific rating curves were used to determine suspended load on the broad database of 55 measured flood events in the lahnenwiesgraben a good correlation r pearson 0 9 between event peak discharge and suspended load of the event was established effective discharge was calculated for the different types of sediment load solid and dissolved and total load in the reintal effective discharge for total load is found in low flow classes close to mean discharge because sediment output is dominated by dissolved load which has its maximum efficiency at low and moderate discharges in the lahnenwiesgraben most work is done by discharges much higher than mean discharge during extreme individual flood events

rock magnetic criteria for the detection of biogenic magnetite abstract we report results on the magnetic properties of magnetites produced by magnetotactic and dissimilatory iron reducing bacteria magnetotactic bacterial mtb strains ms1 mv1 and mv2 and dissimilatory iron reducing bacterium strain gs 15 grown in pure cultures were used in this study our results suggest that a combination of room temperature coercivity analysis and low temperature remanence measurements provides a characteristic magnetic signature for intact chains of single domain sd particles of magnetite from mtbs the most useful magnetic property measurements include 1 acquisition and demagnetization of isothermal remanent magnetization irm using static pulse and alternating fields 2 acquisition of anhysteretic remanent magnetization arm and 3 thermal dependence of low temperature 20 k saturation irm after cooling in zero field zfc or in a 2 5 t field fc from 300 k however potentially the most diagnostic magnetic parameter for magnetosome chain identification in bulk sediment samples is related to the difference between low temperature zero field and field cooled sirms on warming through the verwey transition t 100 k intact chains of unoxidized magnetite magnetosomes have ratios of fc zfc greater than 2 where the parameter is a measure of the amount of remanence lost by warming through the verwey transition disruption of the chain structure or conversion of the magnetosomes to maghemite reduces the fc zfc ratio to around 1 similar to values observed for some inorganic magnetite maghemite greigite and gs 15 particles numerical simulations of fc zfc ratios for simple binary mixtures of magnetosome chains and inorganic magnetic fractions suggest that the fc zfc parameter can be a sensitive indicator of biogenic magnetite in the form of intact chains of magnetite magnetosomes and can be a useful magnetic technique for identifying them in whole sediment samples the strength of our approach lies in the comparative ease and rapidity with which magnetic measurements can be made compared to techniques such as electron microscopy

erratum to the control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment earth planet sci lett 237 2005 462 479

large scale erosion rates from in situ produced cosmogenic nuclides in european river sediments abstract we have calculated long term erosion rates of 20 100 mm kyr from quartz contained 10be in the bedload of middle european rivers for catchments ranging from 102 to 105 km2 these rates average over 10 40 kyr and agree broadly with rock uplift incision and exhumation rates historic soil erosion rates and erosion rates calculated from the measured sediment loads of the same rivers moreover our new erosion rate estimates correlate well with lithology and relief however in the regen neckar loire and meuse catchments cosmogenic nuclide derived erosion rates are consistently 1 5 4 times greater than the equivalent rates derived from measured river loads this may be due to the systematic under representation of high magnitude low frequency transport events in the gauging records which cover less than a century alternatively the discrepancy may derive from spatially non uniform erosion and preferential tapping of deeper sections of the irradiation profile a third explanation relates the high cosmogenic nuclide derived erosion rates to inheritance of an elevated pleistocene erosion signal uncertainties associated with the cosmogenic nuclide derived erosion rate estimates are not greater than the potential errors in conventional estimates therefore the cosmogenic nuclide approach is an effective tool for rapid catchment wide assessment of time integrated rates of bedrock weathering and erosion and we anticipate its fruitful application to the quaternary sedimentary record

rock magnetic properties of uncultured magnetotactic bacteria abstract understanding the magnetic properties of magnetite crystals fe3o4 produced by magnetotactic bacteria mtbs is of fundamental interest in fields of geosciences biomineralization fine particle magnetism and planetary sciences the database of bulk magnetic measurements on mtbs is however still too sparse to allow for generalizations due to difficulties in obtaining bacteria cells in sufficient quantities from natural environments and the fact that only a few cultivable strains are available here we report the first series of magnetic measurements on two air dried samples containing solely mtbs wild type cocci and magnetobacterium bavaricum which were directly isolated from carbonaceous lake sediments systematic rock magnetic studies show that 1 the magnetosomes in cells are dominated by single domain sd magnetite 2 the samples have delta ratios fc zfc higher than 2 3 the measured low temperature remanence cycling curves as well as the first order reversal curve forc diagrams are significantly different to those measured on synthetic sd magnetite samples and 4 the verwey transition temperature tv 100 k of mtb cells is distinctly lower than that from stoichiometric magnetite tv 120 125 k our results provide new insights on the magnetic properties of bacterial magnetite and advance the use of magnetic proxies for decoding the paleomagnetic signals of sediments containing bacterial magnetite

biogeochemical remanent magnetization in pelagic sediments of the western equatorial pacific ocean paleomagnetic data from pelagic sediments are an important source of information on the history of the geomagnetic field however fundamental uncertainties about how these sediments acquire their magnetizations remain here we address whether biogenic magnetite formed at depth within the sediments can contribute to remanent magnetizations in sediments of the western equatorial pacific ocean odp site 805 biogenic magnetite found near the fe redox boundary carries a natural remanent magnetization because the production of biogenic magnetite is tied to the geochemical zonation of the sediments we call this magnetization a biogeochemical remanence these data indicate that some pelagic sediments can continue to acquire remanence significantly after the post depositional lock in of detrital magnetic grains

temporal distribution of suspended sediment transport in a mediterranean basin the lower tordera ne spain abstract suspended sediment dynamics are still imperfectly understood especially in areas of mediterranean climate with strong seasonal contrasts where few studies have been conducted the aim of this study is to analyze the variability in the suspended sediment load at different temporal scales within flood variability monthly seasonal and annual in the tordera river 894 km 2 located in northeastern spain suspended sediment samples were obtained during base flows q 3 5 m 3 s 1 and flood events q 3 5 m 3 s 1 the analysis of the variability in the suspended sediment is structured in two consecutive steps i the construction of statistical relations between suspended sediment concentrations c and discharge q and ii the application of those relations to assess the suspended sediment yield the results show that in a single event the sediment peak generally precedes the peak discharge following a clockwise hysteretic loop furthermore it was observed that the reduction in the suspended sediment concentrations in a sequence of events can be mainly associated with a phenomenon of sediment exhaustion the total amount of suspended sediment transported during a single flood is thus related to its duration and time during the year as well as to its magnitude at a seasonal scale the export of suspended sediment takes place in two phases i sediment preparation and ii sediment transfer and exhaustion during the latter phase the exhaustion of the sediment load is primarily related to the sequence of flood events at the annual scale the results show high inter annual variability according to the number of floods recorded yearly since almost all the suspended load is transported during those events

stratigraphic and structural relationships between meso cenozoic lagonegro basin and coeval carbonate platforms in southern apennines italy abstract stratigraphic studies and facies analysis integrated with a new geological and structural survey of the meso cenozoic units outcropping in the campania lucania apennines southern italy allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during oligo miocene times the southern apennines are a n150 striking and ne verging fold and thrust belt mainly derived from the deformation of the african apulian passive margin four wide belts with different features have been recognized in the chain area from east to west the following units outcrop a successions characterized by basinal to marginal facies ranging in age from cretaceous to miocene tectonically lying on plio pleistocene foredeep deposits b successions characterized by shallow water basinal and shelf margin facies ranging in age from middle triassic to miocene lagonegro units overthrust on the previous ones c triassic to miocene carbonate platform successions apenninic platform units overthrust on the lagonegro units d jurassic cretaceous to miocene deep water successions ophiolite bearing or internal units and associated siliciclastic wedges outcropping along the tyrrhenian belt and the calabria lucania boundary overthrust on the apenninic platform units all these units tectonically lie on the buried apulian platform which is covered at least in the eastern sector of the chain by pliocene to pleistocene foredeep deposits stratigraphic patterns of the cretaceous to lower miocene lagonegro successions are coherent with the platform margin ones calcareous clastics of the lagonegro basin are in fact supplied by an adjacent western platform as inferred by several sedimentological evidences slump and palaeocurrent directions and decreasing grain size towards the depocentre of the basin tectonic relationships among the different units of the chain with particular emphasis on the lagonegro and apenninic platform units of the lucanian segment are shown by means of both regional and detailed geological cross sections the lagonegro units constantly underlie the carbonate units originating from detachment and thrusting of the western platform and overlie the eastern i e apulian platform the lagonegro units show a strong lateral variability of map scale structures dome and basin folds are in fact largely observable in the lucanian apennine further the belt is widely affected by plio quaternary strike slip and extensional faults yet excluding the brittle deformation due to quaternary faulting the complexity of structural styles seems to result from the neogene refolding of more ancient structures produced by oligo miocene intraplate deformation this hypothesis is supported by two independent lines of evidence the first is the recognition of unconformities between the lower miocene numidian sandstone and the underlying lagonegro successions at least in the southwestern sectors the second is that the internal i e western platform remains undeformed until the early miocene both stratigraphic and structural data suggest an external position of the meso cenozoic lagonegro basin with regard to the coeval apenninic platform

micromagnetics of paleomagnetically significant mineral grains with complex morphology 1 micromagnetic calculations relevant to paleomagnetism have generally focused on ideal shapes such as spheres and cubes however oxide grains that occur naturally in rocks often have irregular morphologies highly skeletal dendritic forms being particularly common to investigate the potential effects of complex grain morphology on magnetic stability we have carried out two parallel sets of calculations the first is based on randomly distorted 30 120 nm magnetite spheres we use a three dimensional finite element boundary integral micromagnetic model able to generate suitable morphologies unrestricted by the regular cell structure required by finite difference models the second model consists of a 300 nm magnetite octahedron from which most of the material has been removed to leave a small octahedral crystallite at each of the six apices connected by an orthogonal framework of thin rods the results obtained imply that micromagnetic models currently provide no unambiguous evidence that morphological complexities endow magnetite nanoparticles with enhanced coercivity

detection of noninteracting single domain particles using first order reversal curve diagrams we present a highly sensitive and accurate method for quantitative detection and characterization of noninteracting or weakly interacting uniaxial single domain particles unisd in rocks and sediments the method is based on high resolution measurements of first order reversal curves forcs unisd particles have a unique forc signature that can be used to isolate their contribution among other magnetic components this signature has a narrow ridge along the hc axis of the forc diagram called the central ridge which is proportional to the switching field distribution of the particles therefore the central ridge is directly comparable with other magnetic measurements such as remanent magnetization curves with the advantage of being fully selective to sd particles rather than other magnetic components this selectivity is unmatched by other magnetic unmixing methods and offers useful applications ranging from characterization of sd particles for paleointensity studies to detecting magnetofossils and ultrafine authigenically precipitated minerals in sediments

plastic and viscous shear displacements of a deep and very slow landslide in stiff clay formation deep and superficial displacements have been measured since 2005 in a slow active landslide that has occurred in a stiff clay formation of the italian southern apennines recently new inclinometer casings have been installed to achieve further information on the displacement field in this paper standard inclinometer profiles and fixed in place probe data are analysed over time new data confirm previous hypotheses on geometry and kinematics and add more information on the viscous component of displacements the mechanism of movement in most of the track essentially corresponds to sliding localized on a shear surface consistently with stress and strength distribution however locally internal viscous deformations also occur especially in the weathered and softened zones of the landslide and contribute to the soil discharge continuity viscous displacements can be interpreted by a simplified rheological model based on the bingham equation the residual shear strength has been considered as the creep threshold value and the dynamic viscosity has been considered dependent on the stress level on the basis of long term direct shear tests under controlled shear stresses which were carried out in laboratory

possible stick slip behavior before the rausu landslide inferred from repeating seismic events a precursory sequence of repeating earthquakes was recorded before the rausu landslide in hokkaido japan on april 24 2015 there were two seismic sequences with each consisting of very similar waveforms and leading up to significant landslide movements the nearly identical waveform shapes indicate similar source locations and mechanisms so repeated events originated on a particular small area this sequence is interpreted as stick slip movement on a small patch leading up to the larger landslide failure our observations show that heterogeneous structure such as asperities on the slip surface can play an important role in the initiation of landslides adding a new aspect to the conventional understanding of mechanisms controlling large mass movements

ferromagnetic resonance and magnetic characteristics of intact magnetosome chains in magnetospirillum gryphiswaldense abstract the magnetic characteristics of intact magnetosome chains in magnetospirillum gryphiswaldense bacteria were investigated by means of static and dynamic magnetic analyses and ferromagnetic resonance spectroscopy the nano sized magnetosomes are generally in a stable single domain state but magnetosomes smaller than 30 nm characteristic of superparamagnetic magnetite particles were also found alternating current ac susceptibility indicates that all magnetosomes are blocked below 150 k at room temperature the anisotropy of m gryphiswaldense is dominated by the shape of the magnetosome chains low temperature ferromagnetic resonance fmr spectroscopy indicates that this dominant shape anisotropy can affect the detection of the verwey transition at 100 k the static and dynamic magnetic analyses show that the verwey transition is smeared and that our magnetotactic bacteria fail the moskowitz test this failure is explained by the biomineralization of non stoichiometric magnetosomes this interpretation is based on the increase in high field susceptibility and the distinct peak in the out of phase component of the ac susceptibility below 50 k these results are attributed to freezing of spins associated with defect structures in the core and at the surface of nano sized magnetosomes the results obtained from m gryphiswaldense demonstrate that intrinsic properties of nano sized magnetosomes are significantly influenced by non stoichiometry and by the anisotropy excited from their arrangement in the bacteria

theoretical considerations on the anhysteretic remanent magnetization of interacting particles with uniaxial anisotropy 1 the anhysteretic remanent magnetization arm is widely used in rock magnetism and paleomagnetism because of its sensitivity to the domain state of magnetic particles and the close analogy to natural remanent magnetizations on the other hand the arm shares with other weak field magnetizations the property of being extremely sensitive to magnetostatic interactions therefore it is desirable to model the effects of interactions on natural assemblages of magnetic particles direct micromagnetic calculations of the arm acquisition process are not practicable therefore an analytical approach is used calculate the arm susceptibility of a system of interacting single domain sd particles the model is based on a statistical description of the interaction field the equations obtained have been used to evaluate the dependence of the arm on the packing fraction of the magnetic particles the effect of interactions on the anisotropy of arm aarm was evaluated as well the aarm of densely packed particles is complex and depends critically on the microcoercivity a physical interpretation of the aarm of highly interacting particles is therefore difficult

frequency of proterozoic geomagnetic superchrons abstract long term geodynamo evolution is expected to respond to inner core growth and changing patterns of mantle convection three geomagnetic superchrons during which earth s magnetic field maintained a near constant polarity state through tens of myr are known from the bio magnetostratigraphic record of phanerozoic time perhaps timed according to supercontinental episodicity some geodynamo simulations incorporating a much smaller inner core as would have characterized proterozoic time produce field reversals at a much lower rate here we compile polarity ratios of site means within a quality filtered global proterozoic paleomagnetic database according to recent plate kinematic models various smoothing parameters optimized to successfully identify the known phanerozoic superchrons indicate 3 10 possible proterozoic superchrons during the 1300 myr interval studied proterozoic geodynamo evolution thus appears to indicate a relatively narrow range of reversal behavior through the last two billion years implying either remarkable stability of core dynamics over this time or insensitivity of reversal rate to core evolution

on steady states in mountain belts the dynamic system of tectonics and erosion contains important feedback mechanisms such that orogenic systems tend toward a steady state this concept is often invoked but the nature of the steady state is commonly not specified we identify four types of steady state that characterize the orogenic system and illustrate these cases by using numerical model results and natural examples these types are 1 flux steady state 2 topographic steady state 3 thermal steady state and 4 exhumational steady state they refer to the erosional flux the topography the subsurface temperature field and the spatial pattern of cooling ages respectively models suggest that the topography will reach a steady mean form at the scale of an orogenic belt but perfect topographic steady state is unlikely to be achieved at shorter length scales thermal steady state is a precondition for exhumational steady state and in the case of temperature dependent deformation topographic steady state exhumational steady state is characterized by reset age zones spatially nested according to closure temperature as illustrated in natural systems from new zealand the cascadia accretionary margin and taiwan

late and post variscan cooling and exhumation history of the northern rhenish massif and the southern ruhr basin new constraints from fission track analysis apatite fission track analyses were carried out on outcrop and core samples from the rhenish massif and the carboniferous ruhr basin germany in order to study the late and post variscan thermal and exhumation history apatite fission track ages range from 291 15 ma lower permian to 136 7 ma lower cretaceous and mean track lengths vary between 11 6 m and 13 9 m mostly displaying unimodal distributions with narrow standard deviations all apatite fission track ages are younger than the corresponding sample stratigraphic age indicating substantial post depositional annealing of the apatite fission tracks this agrees with results from maturity modelling which indicates 3500 7000 m eroded devonian and carboniferous sedimentary cover numerical modelling of apatite fission track data predicts onset of exhumation and cooling not earlier than 320 ma in the rhenish massif and 300 ma in the ruhr basin generally followed by late carboniferous triassic cooling to below 50 60 c rapid late variscan cooling was followed by moderate mesozoic cooling rates of 0 1 0 2 c ma converting into denudation rates of 1 mm a assuming a stable geothermal gradient of 30 c km modelling results also give evidence for some late triassic and early jurassic heating and or burial which is supported by sedimentary rocks of the same age preserved at the rim of the lower rhine basin and in the subsurface of the central and northern ruhr basin cenozoic exhumation and cooling of the rhenish massif is interpreted as an isostatic response to former erosion and major base level fall caused by the subsidence in the lower rhine basin

biomineralization crystallography and magnetic properties of bullet shaped magnetite magnetosomes in giant rod magnetotactic bacteria article i nfo magnetosomes produced by magnetotactic bacteria are of great interest for understanding bacterial biomineralization along with sedimentary magnetism and environmental magnetism one of the most intriguing species magnetobacterium bavaricum can synthesize hundreds of bullet shaped magnetite magnetosomes per cell which contribute significantly to magnetic properties of sediments however the biomineralization mechanism and magnetic properties of such magnetosomes remain unknown in this paper we have conducted a comprehensive study of the crystallography and magnetic properties of bullet shaped magnetosomes formed by uncultivated giant rod magnetotactic bacteria referred to as myr 1 recently discovered in lake miyun beijing china transmission electron microscopy observations reveal that each myr 1 cell contains hundreds of bullet shaped magnetite magnetosomes which are arranged into 3 5 braid like bundles of chains the formation of the bullet shaped magnetosomes can be divided into two stages initial isotropic growth up to 20 nm followed by elongation along the 100 direction which is unusual compared with the expected 111 magnetic easy axis although the 100 orientation is the hard axis of the face centered cubic magnetite the shape anisotropy of bullet shaped magnetosomes and intra bundle magnetostatic interactions confine the magnetization direction of the chain along the long axis of the cell bundle due to each bundle of magnetosome chains effectively behaving as an elongated single domain particle the myr 1 cells show high coercivity weak intra bundle magnetostatic interaction and high ratio these results provide new insights into the biomineralization process and magnetic properties of bullet shaped magnetite magnetosomes

ferromagnetic resonance and low temperature magnetic tests for biogenic magnetite magnetite is both a common inorganic rock forming mineral and a biogenic product formed by a diversity of organisms magnetotactic bacteria produce intracellular magnetites of high purity and crystallinity magnetosomes arranged in linear chains of crystals magnetosomes and their fossils magnetofossils have been identified using transmission electron microscopy tem in sediments dating back to 510 570 ma and possibly in 4 ga carbonates in martian meteorite alh84001 we present the results from two rock magnetic analyses the low temperature moskowitz test and ferromagnetic resonance fmr applied to dozens of samples of magnetite and other materials the magnetites in these samples are of diverse composition size shape and origin biologically induced extracellular biologically controlled magnetosomes and chiton teeth magnetofossil synthetic and natural inorganic we confirm that the moskowitz test is a distinctive indicator for magnetotactic bacteria and provide the first direct experimental evidence that this is accomplished via sensitivity to the magnetosome chain structure we also demonstrate that the fmr spectra of four different strains of magnetotactic bacteria and a magnetofossil bearing carbonate have a form distinct from all other samples measured in this study we suggest that this signature also results from the magnetosomes unique arrangement in chains because fmr can rapidly identify samples with large fractions of intact isolated magnetosome chains it could be a powerful tool for identifying magnetofossils in sediments

a strong angular dependence of magnetic properties of magnetosome chains implications for rock magnetism and paleomagnetism 1 single domain magnetite particles produced by magnetotactic bacteria magnetosomes and aligned in chains are of great interest in the biosciences and geosciences here we investigated angular variation of magnetic properties of aligned magnetospirillum magneticum amb 1 cells each of which contains one single fragmental chain of magnetosomes with measurements at increasing angles from the chain direction we observed that i the hysteresis loop gradually changes from nearly rectangular to a ramp like shape e g bc and remanence decrease ii the acquisition and demagnetization curves of irm shift toward higher fields e g bcr increases and iii the forc diagram shifts toward higher coercivity fields e g bc forc increases for low temperature results compared to unoriented samples the samples containing aligned chains have a much lower remanence loss of field cooled fc and zero field cooled zfc remanence upon warming through the verwey transition higher ratio fc zfc for the measurement parallel to the chain direction and lower ratio larger fc and zfc values for the perpendicular measurement micromagnetic simulations confirm the experimental observations and reveal that the magnetization reversal of magnetosome chain appears to be noncoherent at low angles and coherent at high angles the simulations also demonstrate that the angular dependence of magnetic properties is related to the dispersion degree of individual chains indicating that effects of anisotropy need to be accounted for when using rock magnetism to identify magnetosomes or magnetofossils once they have been preserved in aligned chains additionally this study experimentally demonstrates an empirical correspondence of the parameter bc forc to bcr rather than bc at least for magnetite chains with strong shape anisotropy this suggests forc analysis is a good discriminant of magnetofossils in sediments and rocks

magnetotactic bacterial response to antarctic dust supply during the palaeocene eocene thermal maximum distinct magnetic properties of marine sediments that record the palaeocene eocene thermal maximum petm have been suggested to be due to a bacterial magnetofossil signal that is linked to enhanced weathering conditions during the petm we document the dominance of bacterial magnetite in deep sea sediments from southern kerguelen plateau ocean drilling program hole 738c southern ocean not only during the petm but also before and after the thermal event this occurrence of magnetofossils throughout the petm indicates that the occurrence of bacterial magnetosomes is not due to a preservation effect instead we suggest that it is due to sustained mild iron reducing conditions that dissolved the most labile aeolian derived iron which favoured continued magnetotactic bacterial activity without being strong enough to dissolve the less reactive magnetite and haematite enhanced aeolian haematite abundances at the beginning of the petm indicate drier conditions on the neighbouring antarctic continent at those times our results provide evidence that iron fertilisation by aeolian dust was the main limiting factor that conditioned proliferation of magnetotactic bacteria in the deep sea at the southern kerguelen plateau with the exception of two short periods of rapidly changing palaeoenvironmental conditions at the onset and termination of the petm increased iron supply from aeolian dust that enhanced oceanic primary productivity and subsequent delivery of organic carbon to the seafloor along with mild iron reducing diagenetic conditions seem to have been necessary to provide the iron needed for magnetite biomineralization by magnetotactic bacteria to drive their marked increase in abundance in the studied petm record from southern kerguelen plateau our analyses of a deep sea petm record from hole 1051b at blake nose atlantic ocean failed to identify magnetofossils despite evidence for the occurrence of magnetite and haematite of probable aeolian origin contrasting magnetic properties at these petm sections indicate that further work is needed to understand the palaeoenvironmental and diagenetic factors whose interactions lead to production and preservation of magnetofossils in deep sea sediments

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

suspended sediment load during floods in a small stream of the dolomites northeastern italy abstract suspended sediment load was analyzed in a small high gradient stream of the eastern italian alps which was instrumented to measure discharge and sediment transport the ratio of suspended to total sediment yield and the relations between sediment concentration and water discharge were analyzed for seven floods which occurred from 1991 to 1996 in summer and autumn from june to october different patterns of hysteresis in the relation between suspended sediment and discharge were related to types and locations of active sediment sources the within storm variation of particle size of suspended sediment during a major flood indicates a coarsening of transported material for increasing discharge an analysis of grain size has shown that erosion areas on hillslopes were the main sources of suspended load

influence of slip surface geometry on earth flow deformation montaguto earth flow southern italy we investigated relations between slip surface geometry and deformational structures and hydrologic features at the montaguto earth flow in southern italy between 1954 and 2010 we used 25 boreholes 15 static cone penetration tests and 22 shallow seismic profiles to define the geometry of basal and lateral slip surfaces and 9 multitemporal maps to quantify the spatial and temporal distribution of normal faults thrust faults back tilted surfaces strike slip faults flank ridges folds ponds and springs we infer that the slip surface is a repeating series of steeply sloping surfaces risers and gently sloping surfaces treads stretching of earth flow material created normal faults at risers and shortening of earth flow material created thrust faults back tilted surfaces and ponds at treads individual pairs of risers and treads formed quasi discrete kinematic zones within the earth flow that operated in unison to transmit pulses of sediment along the length of the flow the locations of strike slip faults flank ridges and folds were not controlled by basal slip surface topography but were instead dependent on earth flow volume and lateral changes in the direction of the earth flow travel path the earth flow travel path was strongly influenced by inactive earth flow deposits and pre earth flow drainages whose positions were determined by tectonic structures the implications of our results that may be applicable to other earth flows are that structures with strikes normal to the direction of earth flow motion e g normal faults and thrust faults can be used as a guide to the geometry of basal slip surfaces but that depths to the slip surface i e the thickness of an earth flow will vary as sediment pulses are transmitted through a flow

post failure evolution analysis of a rainfall triggered landslide by multi temporal interferometry sar approaches integrated with geotechnical analysis persistent scatterers interferometry psi represents one of the most powerful techniques for earth s surface deformation processes monitoring especially for long term evolution phenomena in this work a dataset of 34 terrasar x stripmap images october 2013 october 2014 has been processed by two psi techniques coherent pixel technique temporal sublook coherence cpt tsc and small baseline subset sbas in order to study the evolution of a slow moving landslide which occurred on february 23 2012 in the papanice hamlet crotone municipality southern italy and induced by a significant rainfall event 185 mm in three days the mass movement caused structural damage buildings collapse and destruction of utility lines gas water and electricity and roads the results showed analogous displacement rates 30 40 mm yr along the line of sight los of the satellite with respect to the pre failure phase 2008 2010 analyzed in previous works both approaches allowed detect the landslide affected area however the higher density of targets identified by means of cpt tsc enabled to analyze in detail the slope behavior in order to design possible mitigation interventions for this aim a slope stability analysis has been carried out considering the comparison between groundwater oscillations and time series of displacement hence the crucial role of the interaction between rainfall and groundwater level has been inferred for the landslide triggering in conclusion we showed that the integration of geotechnical and remote sensing approaches can be seen as the best practice to support stakeholders to design remedial works

environmental magnetism principles and applications 1 in environmental magnetism rock and mineral magnetic techniques are used to investigate the formation transportation deposition and postdepositional alterations of magnetic minerals under the influences of a wide range of environmental processes all materials respond in some way to an applied magnetic field and iron bearing minerals are sensitive to a range of environmental processes which makes magnetic measurements extremely useful for detecting signals associated with environmental processes environmental magnetism has grown considerably since the mid 1970s and now contributes to research in the geosciences and in branches of physics chemistry and biology and environmental science including research on climate change pollution iron biomineralization and depositional and diagenetic processes in sediments to name a few applications magnetic parameters are used to routinely scan sediments but interpretation is often difficult and requires understanding of the underlying physics and chemistry thorough examination of magnetic properties and of the environmental processes that give rise to the measured magnetic signal is needed to avoid ambiguities complexities and limitations to interpretations in this review we evaluate environmental magnetic parameters based on theory and empirical results we describe how ambiguities can be resolved by use of combined techniques and demonstrate the power of environmental magnetism in enabling quantitative environmental interpretations we also review recent developments that demonstrate the mutual benefit of environmental magnetism from close collaborations with biology chemistry and physics finally we discuss directions in which environmental magnetism is likely to develop in the future

on the reactivation of a large landslide induced by rainfall in highly fissured clays abstract the paper discusses the field investigations geotechnical characterization and time evolution of horizontal displacements in a wide landslide the latter triggered by an earthquake occurring in september 2002 is located in sicily and involves a thick body of stiff and highly fissured clays belonging to a varicoloured clay formation in order to characterise the reactivation of landslide mechanisms induced by rainfall a three year monitoring programme 2008 2011 was implemented to measure rain pore water pressures and deep and superficial displacements the monitoring data made it possible to recognize three distinct landslides which evolve at variable rates in different directions within the overall landslide area the landslides were reactivated by the increase in pore water pressures in the period autumn 2009 spring 2010 the data clearly show the mechanical role of pore water pressures in the stability of the slope and point out the dependence of the time evolution of the horizontal displacement on the pore water pressure variation induced by rainfall back analysis carried out on the single landslides confirmed that they are reactivated ones since the residual shear strength is mobilised on the pre existing sliding surfaces the pore water pressure variation and the landslide body displacement rates can be effectively related to 5 month cumulative rainfall by simple models characterised by three parameters these models calibrated on the period october 2009 september 2010 made it possible to predict the horizontal displacement rates in the ensuing time period the displacements forecasted by the model in the period september 2010 may 2011 agree very well with the measured ones

geochemistry of dissolved and suspended loads of the seine river france anthropogenic impact carbonate and silicate weathering this study focuses on the chemistry of the seine river system one of the major rivers in europe and constitutes the first geochemical investigation of both suspended and dissolved loads of this river the seine river drains a typical mesozoic cenozoic sedimentary basin the paris basin constituted of limestones mixed or interbedded with terrigenous sediments derived from the paleoreliefs bordering the mesozoic and cenozoic seas in the context of quantifying the global influence of carbonate and silicate weathering on atmospheric co2 consumption the seine river offers the possibility of examining weathering rates in a flat sedimentary environment under temperate climatic conditions one of the major problems associated with the seine river as with many temperate rivers is pollution we propose in this paper 2 approaches in order to correct the dissolved load of the seine river for anthropogenic inputs and to calculate weathering rates of carbonates and silicates the first uses the dissolved load of rivers and tries to allocate the different solutes to different sources a mixing model based on elemental ratios is established and solved by an inversion technique the second approach consists in using the suspended load geochemistry under steady state conditions we show that the geochemistry of suspended sediments makes it possible to estimate the amount of solutes released during the chemical weathering of silicates and thus to calculate weathering rates of silicates the total dissolved load of the seine river at paris can be decomposed into 2 of solutes derived from natural atmospheric sources 7 derived from anthropogenic atmospheric sources 6 derived from agriculture 3 derived from communal inputs and 82 of solutes derived from rock weathering during high floods the contribution of atmospheric and agriculture inputs predominates the weathering rate of carbonates is estimated to be 48 t km2 yr 25 mm 1000 yr only 10 of carbonates are transported in a solid form the rest being transported in solution co2 consumption by carbonate weathering approaches 400 103 mol km2 yr in the seine river at paris about 2 3 mg l of dissolved cations are found to originate from the chemical weathering of silicates by taking dissolved silica into accounts the total dissolved load derived from silicate weathering is about 6 7 mg l this value is minimal because biological uptake of silica probably occur in the seine river the chemical weathering rate of aluminosilicates is estimated to be 2 t km2 yr the ratio of physical over chemical weathering of silicates range between 1 and 3 and the total chemical and physical erosion rates of sedimentary silicates are about 2 3 mm kyr the co2 consumption by silicate weathering 15 24 103 mol km2 yr and is independent of dissolved silica concentration silicate consumption is thus 20 times less than carbonate consumption in the paris basin compared to the neighboring granitic areas the sedimentary region drained by the seine river has 2 to 3 times lower co2 consumption rates we attribute this difference to the cation depleted nature of the seine basin aluminosilicates which are of sedimentary origin at a world scale the chemical denudation rates found for the seine basin are very low and comparable to those given for tropical lowland rivers draining silicates such as the rivers of the congo and amazon basins in spite of huge climatic differences we attribute this similarity to the low mechanical denudation that characterizes these two types of regions

searching for single domain magnetite in the pseudo single domain sedimentary haystack implications of biogenic magnetite preservation for sediment magnetism and relative paleointensity determinations 1 magnetic hysteresis measurements of sediments have resulted in widespread reporting of pseudo single domain like magnetic properties in contrast the ideal single domain sd properties that would be expected to be responsible for high quality paleomagnetic records are rare determining whether sd particles are rare or common in sediments requires application of techniques that enable discrimination among different magnetic components in a sediment we apply a range of such techniques and find that sd particles are much more common than has been reported in the literature and that magnetite magnetofossils the inorganic remains of magnetotactic bacteria are widely preserved at depth in a range of sediment types including biogenic pelagic carbonates lacustrine and marine clays and possibly even in glaci marine sediments thus instead of being rarely preserved in the geological record we find that magnetofossils are widespread this observation has important implications for our understanding of how sediments become magnetized and highlights the need to develop a more robust basis for understanding how biogenic magnetite contributes to the magnetization of sediments magnetofossils also have grain sizes that are substantially smaller than the 1 15 m size range for which there is reasonable empirical support for relative paleointensity studies the different magnetic response of coexisting fine biogenic and coarser lithogenic particles is likely to complicate relative paleointensity studies this issue needs much closer attention despite the fact that sediments have been subjected to paleomagnetic investigation for over 60 years much remains to be understood about how they become magnetized

relation between rock uplift and denudation from cosmogenic nuclides in river sediment in the central alps of switzerland 1 a north south traverse through the swiss central alps reveals that denudation rates correlate with recent rock uplift rates in both magnitude and spatial distribution this result emerges from a study of in situ produced cosmogenic 10be in riverborne quartz in central alpine catchments as a prerequisite we took care to investigate the potential influence of shielding from cosmic rays due to snow glaciers and topographic obstructions to calculate a possible memory from last glacial maximum lgm glaciation and to identify a watershed size that is appropriate for systematic sampling mean denudation rates are 0 27 0 14 mm a for the alpine foreland and 0 9 0 3 mm a for the crystalline central alps the measured cosmogenic nuclide derived denudation rates are in good agreement with post lgm lake infill rates and are about twice as high as denudation rates from apatite fission track ages that record denudation from 9 to 5 ma in general denudation rates are high in areas of high topography and high crustal thickness the similarity in the spatial distribution and magnitude of denudation rates and those of rock uplift rates can be interpreted in several ways 1 postglacial rebound or climate change has introduced a transient change in which both uplift and denudation follow each other with a short lag time 2 the amplitude of glacial to interglacial changes in both is small and is contained in the scatter of the data 3 both are driven by ongoing convergence where their similarity might hint at some form of long term quasi steady state or 4 enhanced continuous quaternary erosion and isostatic compensation of the mass removed accounts for the distribution of present day rock uplift

erosion rates on different timescales derived from cosmogenic 10 be and river loads implications for landscape evolution in the rhenish massif germany we determined erosion rates on timescales of 101 104 years for two catchments in the northeastern rhenish massif in order to unravel the quaternary landscape evolution in a variscan mountain range typical of central europe spatially averaged erosion rates derived from in situ produced 10be concentrations in stream sediment of the aabach and mohne watersheds range from 47 6 to 65 14 mm ka and integrate over the last 9 13 ka these erosion rates are similar to local rates of river incision and rock uplift in the quaternary and to average denudation rates since the mesozoic derived from fission track data this suggests that rock uplift is balanced by denudation i e the landscape is in a steady state short term erosion rates were derived from suspended and dissolved river loads subsequent to 1 correcting for atmospheric and anthropogenic inputs 2 establishing calibration curves that relate the amount of suspended load to discharge and 3 estimating the amount of bedload the resulting solid mass fluxes suspended and bedload agree with those derived from the sediment volume trapped in three reservoirs however resulting geogenic short term erosion rates range from 9 to 25 mm ka and are only about one third of the rates derived from 10be model simulations in combination with published sediment yield data suggest that this discrepancy is caused by at least three factors 1 phases with higher precipitation and or lower evapotranspiration 2 rare flood events not captured in the short term records and 3 prolonged periods of climatic deterioration with increased erosion and sediment transport on hillslopes

long term investigations on the pore pressure regime in saturated and unsaturated sloping soils abstract pore pressure changes play a major role in the stability of natural slopes whose safety factor value is usually much smaller than that generally accepted in any other geotechnical problem correct assessment of potential seasonal pore pressure distributions is therefore a crucial issue in slope stability analysis based on long term monitoring of some natural slopes this paper compares the pore pressure distribution recorded in saturated fine grained deposits and in shallow unsaturated granular covers both monitored in southern italy in spite of the expected differences the soils display some common features in particular from december to mid may wet period in all examined cases the pore water pressures are quite constant over a monthly scale thus an essentially steady state pore pressure condition establishes it is in this phase which is characterised by an essentially downward flux that the safety factor drops to its lowest yearly value finally a simplified method is adopted to model the steady state pore pressure during the wet period and to calculate the average rain infiltration in equilibrium with the steady state condition the results thereby obtained are compared with the findings of an advanced approach based on the hydrological balance

dynamic equilibrium among erosion river incision and coastal uplift in the northern and central apennines italy erosion river incision and uplift rates in the northern and central apennines italy since 0 9 ma are determined from new cosmogenic nuclide data beryllium 10 concentrations in modern and middle pleistocene sediments indicate erosion rates from 0 20 to 0 58 mm yr these rates are similar to estimates of sediment yield 0 12 0 44 mm yr river incision 0 35 mm yr and uplift 0 01 1 0 mm yr rates inferred from other methods that integrate landscape process rates since the early pleistocene these rates of landscape change are significantly lower than long term exhumation rates of 1 2 mm yr since ca 4 5 ma inferred from thermochronometry collectively these data suggest that hillslope erosion and river incision rates in the northern and central apennines have balanced local uplift rates for 1 my but that exhumation rates have slowed significantly since emergence of the mountain chain in the pliocene this condition of dynamic equilibrium was potentially achieved within ca 3 ma similar to some model predictions of hillslope and fluvial system adjustment

increase of human over natural erosion rates in tropical highlands constrained by cosmogenic nuclides we quantify the difference between the human caused sediment yield and the natural rates of soil production and bedrock erosion in a now largely deforested tropical highland the present day rate of soil loss in the upper mahaweli catchment sri lanka is calculated by using suspended river load fluxes these data provide spatially averaged sediment yields of 130 2100 t km 2 yr 1 local rates of soil loss from agricultural plots on hillslopes are as high as 7000 t km 2 yr 1 by comparison natural rates of sediment generation as determined by measuring cosmogenic 1 0 be in quartz from sediments and soils are only 13 30 t km 2 yr 1 the natural rates presented here provide a benchmark against which recent erosion rates determined by various sediment gauging techniques can be referenced in the sri lankan highlands these results suggest that soil is now being lost 10 100 times faster from agriculturally utilized areas than it is being produced

rotational translational landslides in the neogene basins at the northeast margin of the tibetan plateau abstract rotational translational landslides are common in neogene basins throughout the world and are of high risk to the public to understand the mechanism of rotational translational failure the spatial distribution and deformation of rotational translational landslides in the northeast of the tibetan plateau are investigated in this study the spatial distribution of these landslides is dependent on the regional tectonics and geomorphology crustal stresses and lithological properties the rotational translational landslides are concentrated in the neogene mudstone basins and the intensities of these landslides are observed to gradually decrease from the hinterland of the plateau to the marginal basins the bedding parallel shear zones within the location of the rotational translational landslides are present in the overconsolidated neogene mudstones with high clay content nearly horizontal tectonic stresses and erosion cause the formation of horizontal shear stresses in the sliding masses in this stress environment materials with low internal friction angle

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

combined use of magnetometry and spectroscopy for identifying magnetofossils in sediments identification of the mineral remains of magnetotactic bacteria mtb known as magnetofossils is of particular interest because their occurrence can be used for environmental and climatic reconstructions single domain magnetite particles which are biomineralized in the cell body of mtb have characteristic properties that can be used to detect their fossil remains acquisition of anhysteretic and isothermal remanent magnetization arm and irm first order reversal curve forc diagrams and ferromagnetic resonance fmr spectra were used to detect the magnetic mineral inventory in holocene lake sediments a comparative analysis in terms of the discriminatory power of these methods is presented the forc diagrams contain two distinct features a sharp horizontal ridge centered on the horizontal axis bc and a feature with symmetric spread along the vertical bb axis the coercivity spectra derived from the central ridge coincides with that derived from arm and irm acquisition curves and is compatible with the presence of noninteracting linear chains of single domain magnetite the second feature on forc diagrams is indicative of interacting particles in clusters in the fmr spectra from bulk sediment two populations are separated empirically based on the forc information an asymmetric signal is taken to describe the population which contains single domain particles in clusters empirical spectral separation of this contribution results in fmr spectra that are similar to those of intact mtb which strongly suggests that a fraction of linear magnetosome chains is present combination of fmr and forc results demonstrates the strong potential of these methods for identifying magnetofossils based on alignment and interaction patterns of magnetic particles

denudation rates determined from the accumulation of in situ produced 10be in the luquillo experimental forest puerto rico we present a simple method for estimation of long term mean denudation rates using in situ produced cosmogenic 10be in fluvial sediments procedures are discussed to account for the effects of soil bioturbation mass wasting and attenuation of cosmic rays by biomass and by local topography our analyses of 10be in quartz from bedrock outcrops soils mass wasting sites and riverine sediment from the icacos river basin in the luquillo experimental forest puerto rico are used to characterize denudation for major landform elements in that basin the 10be concentration of a discharge weighted average of size classes of river sediment corresponds to a long term average denudation of 43 m ma 1 consistent with mass balance results

low temperature remanence in stable single domain magnetite 1 a numerical model is developed in order to simulate the loss of low temperature remanence while warming through the verwey transition we concentrate on the amount of remanence lost fc and zfc during field cooled and zero field cooled low temperature demagnetization curves for stable single domain ssd particles of 1 inorganic magnetite and 2 biogenic magnetite in the form of magnetosome chains the model predicts that delta ratios fc zfc for inorganic ssd magnetite increase from 1 to 1 6 with increasing aspect ratio and that magnetosome chains have elevated delta ratios of at least 2 0 disaggregated magnetosomes are predicted to behave similarly to inorganic acicular ssd magnetite the numerical results agree with experimental results

the identification and biogeochemical interpretation of fossil magnetotactic bacteria magnetotactic bacteria which most commonly live within the oxic anoxic transition zone oatz of aquatic environments produce intracellular crystals of magnetic minerals specifically magnetite or greigite the crystals cause the bacteria to orient themselves passively with respect to the geomagnetic field and thereby facilitate the bacteria s search for optimal conditions within the sharp chemical gradients of the oatz the bacteria may also gain energy from the redox cycling of their crystals because magnetotactic bacteria benefit from their magnetic moments natural selection has promoted the development of traits that increase the efficiency with which the intracellular crystals impart magnetic moments to cells these traits also allow crystals produced by magnetotactic bacteria called magnetofossils when preserved in sediments to be distinguished from abiogenic particles and particles produced as extracellular byproducts of bacterial metabolism magnetofossils are recognizable based on their narrow size and shape distributions distinctive morphologies with blunt crystal edges chain arrangement chemical purity and crystallographic perfection this article presents a scheme for rating magnetofossil robustness based on these traits the magnetofossil record extends robustly to the cretaceous and with lesser certainty to the late archean because magnetotactic bacteria predominantly live in the oatz the abundance and character of their fossils can reflect environmental changes that alter the chemical stratification of sediments and the water column the magnetofossil record therefore provides an underutilized archive of paleoenvironmental information several studies have demonstrated a relationship between magnetofossil abundance and glacial interglacial cycles likely mediated by changes in pore water oxygen levels more speculatively a better developed magnetofossil record might provide constraints on the long term evolution of marine redox stratification more work in modern and ancient settings is necessary to explicate the mechanisms linking the abundance and character of magnetofossils to ancient biogeochemistry

a micromagnetic investigation of magnetite grains in the form of platonic polyhedra with surface roughness micromagnetic calculations have been carried out for spherical magnetite particles with surface roughness consisting of patterns of conical bumps based on regular platonic convex polyhedra the purpose was to examine the effect of surface irregularities while avoiding overall shape anisotropy which generally plays a dominant role in determining hysteresis properties we considered three morphologies based on the tetrahedron 4 apices the icosahedron 12 apices and the dodecahedron 20 apices grains of three sizes were considered 30 nm single domain sd 90 nm on the single domain pseudo single domain boundary sd psd and 120 nm stable pseudo single domain psd we find that the morphologies investigated have very little effect on the hysteresis parameters of sd and marginal sd psd grains however in the psd grains coercivity increases significantly as bump amplitude increases from 0 1 to 0 9 this lends support to the long standing notion that surface protuberances on larger grains are a possible source of paleomagnetically significant stable remanence although the very high coercivities on the order of 100 mt observed in some rocks cannot be achieved classical stoner wohlfarth shape anisotropy remains the only explanation for such ultra stable remanence in magnetite bearing rocks this is confirmed by a specific example of a model skeletal grain consisting of three orthogonal parallelepipeds

redundancy and coherence of multi method displacement monitoring data as key issues for the analysis of extremely slow landslides isarco valley eastern alps italy abstract the paper describes the study of two extremely slow active continuous deep seated landslides located in the isarco valley eastern alps italy a multiple rotational rock slide mrrs and partial reactivation of a deep seated gravitational slope deformation dsgsd both landslides interact with viaducts on the e45 highway extensive multi method field investigation monitoring of surface and subsurface displacements and limit equilibrium stability analyses were adopted to fully characterize slope dynamics in order to overcome the limitations due to the systematic errors affecting each single monitoring system and analysis method an operative framework based on redundancy and coherence tests was introduced to check the reliability of the data and results in this framework the geological and geotechnical models of the investigated slopes were progressively refined this allowed assessment of the type of interaction between the slopes and the highway viaducts

in situ and satellite long term monitoring of the latronico landslide italy displacement evolution damage to buildings and effectiveness of remedial works abstract the slow and continuous movements of a deep and complex active landslide system cause severe damage to latronico a village of the italian southern apennines in order to obtain a deeper insight in the phenomenon its kinematic features have been investigated by means of both ground based displacement measurements by mobile and fixed in place inclinometers and by the processing of images acquired by synthetic aperture radar sensors ers envisat cosmo skymed satellites the results of the analyses show that the landslide system includes different phenomena at different scales and of different age from old and huge landslides early stage of last post glacial to young shallower reactivations secondary creep and rain induced displacements coexist occurring at different depths the reconstruction of the kinematic history of the inhabited area subsoil system shows that the yearly average displacement rates have been almost constant over the last 25 years several cm year the depth of the slip surfaces and the volumes of the instable soils explain why the numerous and expensive remedial measures and stabilization interventions have had very limited effects if any on the displacement rate field

evidence for bacterial palaeoecological origin of mineral magnetic cycles in oxic and sub oxic tasman sea sediments abstract sediments from the tasman basin in the southwest pacific ocean show a cyclic pattern of variation in mineral magnetic properties including susceptibility and remanence over the brunhes chron the magnetic pattern is dominated by fluctuations in the concentration of a single domain ferrimagnetic component identified as bacterial magnetofossils by tem investigation of the magnetic fraction the intervals of low bacterial magnetite concentration occurring in glacial periods are accompanied by a change of the bacterial magnetosome morphology assemblage interpreted as recording a change in bacterial species assemblage there is no evidence of iron or sulphate reducing conditions during low bacterial magnetite intervals concentrations of bacterial magnetite are low when oxygen concentrations in surface sediment pore waters dropped either as the result of variation in bottom water oxygen concentration or sedimentation rate the variations in the magnetic signal are therefore interpreted as resulting primarily from bacterial palaeoecological control rather than dissolution or alteration the bacteria in this deep sea environment are apparently aerophilic and grow near the sediment surface within the oxic zone implying that magnetic remanence is also acquired near the surface but up to tens of centimetres below where the oxic zone is very thick

natural controls of fluvial denudation rates in major world drainage basins we present a new compilation of estimates of modern rates of mechanical and chemical denudation for externally drained basins exceeding 5 105 km2 in area these estimates are based on sediment and solute load data selected in order to represent natural rates as far as possible chemical denudation rates have been calculated by deducting the nondenudational component of solute load mechanical denudation rates range from 1 mm kyr 1 for the st lawrence and dnepr basins to 670 mm kyr 1 for the brahmaputra basin chemical denudation rates vary from 1 mm kyr 1 kolyma niger nile and rio grande basins to 27 mm kyr 1 chiang jiang basin the kolyma basin has the lowest 4 mm kyr 1 and the brahmaputra basin the highest overall rate of denudation 688 mm kyr 1 relationships between denudation rates and a range of morphometric hydrologic and climatic variables are investigated through correlation and regression analysis morphometric variables such as mean local relief are accurately calculated for large basins for the first time by using the national geophysical data center 10 minute topographic database variables expressing basin relief characteristics and runoff are found to be most strongly associated with both mechanical and chemical denudation rates with more than 60 of the variance in total denudation being accounted for by basin relief ratio and runoff basin area runoff variability and mean temperature however are only weakly associated with rates of denudation although direct comparisons cannot be made it appears that rates of basin denudation derived from present day mass flux estimates are not overall significantly different from estimates of long term rates based on sediment volume and thermochronologic data it therefore appears that the key factors identified as controlling denudation rates here are also applicable to the geological time spans relevant to the interaction between tectonic and denudational processes

strong tectonic and weak climatic control of long term chemical weathering rates the relationships among climate physical erosion and chemical weathering have remained uncertain because long term chemical weathering rates have been difficult to measure here we show that long term chemical weathering rates can be measured by combining physical erosion rates inferred from cosmogenic nuclides with dissolution losses inferred from the rock to soil enrichment of insoluble elements we used this method to measure chemical weathering rates across 22 mountainous granitic catchments that span a wide range of erosion rates and climates chemical weathering rates correlate strongly with physical erosion rates but only weakly with climate implying that by regulating erosion rates tectonic uplift may significantly accelerate chemical weathering rates in granitic landscapes

structure and kinematics of a landslide in a complex clayey formation of the italian southern apennines abstract this paper describes the geometrical structure and the main kinematic features of an ancient and active landslide which develops in structurally complex formations of the southern apennines italy a scaly clayey formation in the medium and lower part of the slope and a stratified marly calcareous rock formation in the upper part the landslide 3d geometry was reconstructed by using topographic data stratigraphies from continuous coring boreholes and inclinometer data the analysis of the kinematic features was based on the measurement of deep and superficial displacements laboratory tests were carried out to evaluate shear strength parameters it was found that in each investigated transversal section of the landslide channel the displacements can be considered uniform and that the decrease of the displacement rates from upslope to downslope mostly depends on the increase in the areas of transversal sections the soil discharge variations being slight stability analyses confirmed that shear strength close to the residual value is available on the slip surface the large difference between residual strength and peak strength of the landslide material is consistent with the displacement uniformity

review of the low temperature magnetic properties of magnetite from a rock magnetic perspective the low temperature magnetic properties of magnetite are reviewed and implications for rock magnetism considered the behaviour of fundamental properties of magnetite at low temperatures near the verwey transition tv are documented and attention is given to various verwey transition theories the low temperature behaviour of the magnetic energies that control domain structure is reviewed in detail for the first time in rock magnetic literature the low temperature anomaly in spontaneous magnetization ms is documented and the differences between the saturation magnetization and ms near the verwey transition are discussed it is argued that the low temperature behaviour of the magnetocrystalline anisotropy and in particular the anomaly at tv is most likely to affect multidomain remanence during low temperature cycling for multidomain crystals it is calculated that the large increase in magnetocrystalline anisotropy intensity and reduction in symmetry on cooling through tv is likely to reduce the stability of closure domains

sediment yield during late glacial and holocene periods in the lac chambon watershed massif central france a sediment budget for the late glacial and holocene periods was calculated for the lac chambon watershed which is located in a formerly glaciated temperate crystalline mountain area it appears that over 15 500 years 1 69 per cent of eroded particles have been displaced by gravity processes and then stored within the watershed compared to 31 per cent that have been displaced by running water and evacuated outward 2 the mean mechanical erosion due to gravity processes on the slopes amounted to 16 1 6 m and only developed on a quarter of the watershed surface whereas the mean mechanical erosion due to running water amounted 1 24 0 37 m and involved the whole watershed surface the mean sediment yields due to gravity processes on slopes were 2300 1360 1770 960 and 380 100 m 3 km 3 a 1 respectively for basalts and basic and acidic trachyandesites values of sediment yield due to running water were 49 15 120 36 and 79 24 m 3 km 2 a 1 respectively during the bolling allerod the younger dryas and the pre boreal boreal periods they were 56 17 and 166 50 m 3 km 2 a 1 during the sub atlantic period before and after 1360 a bp respectively these values reflect variations in the natural environment and the impact of human induced deforestation 1997 by john wiley sons ltd

low temperature magnetic properties of pelagic carbonates oxidation of biogenic magnetite and identification of magnetosome chains 1 pelagic marine carbonates provide important records of past environmental change we carried out detailed low temperature magnetic measurements on biogenic magnetite bearing sediments from the southern ocean ocean drilling program odp holes 738b 738c 689d and 690c and on samples containing whole magnetotactic bacteria cells we document a range of low temperature magnetic properties including reversible humped low temperature cycling ltc curves different degrees of magnetite oxidation are considered to be responsible for the observed variable shapes of ltc curves a dipole spring mechanism in magnetosome chains is introduced to explain reversible ltc curves this dipole spring mechanism is proposed to result from the uniaxial anisotropy that originates from the chain arrangement of biogenic magnetite similar to published results for uniaxial stable single domain sd particles the dipole spring mechanism reversibly restores the remanence during warming in ltc measurements this supports a previous idea that remanence of magnetosome chains is completely reversible during ltc experiments we suggest that this magnetic fingerprint is a diagnostic indicator for intact magnetosome chains although the presence of isolated uniaxial stable sd particles and magnetically interacting particles can complicate this test magnetic measurements through the eocene section of odp hole 738b reveal an interval with distinct magnetic properties that we interpret to originate from less oxidized biogenic magnetite and enrichment of a biogenic hard component co occurrence of these two magnetic fingerprints during the late eocene in the southern ocean indicates less oxic conditions probably due to increased oceanic primary productivity and organic carbon burial

the link between biomineralization and fossilization of bacteria insights from field and experimental studies abstract fossil biominerals and fossils of microorganisms in ancient rocks contain important biogeochemical signals decoding this record may reveal crucial information about the evolution of life on earth and terrestrial paleoenvironments however the identification of traces of life especially in very old rocks is extremely challenging because the morphological and chemical signatures of biominerals and microfossils are subtle of microscopic size and inevitably altered with aging in this review we stress on the fact that biomineralization is often the first step of fossilization and produces particular chemical structural and morphological features that can be preserved in fossil biominerals or microfossils with a special focus on fe biomineralization the taphonomic processes affecting biominerals and microfossils and altering their morphology and or chemical composition over time are then discussed in light of experimental fossilization simulations and field sample analyses we suggest that taxonomic biases observed in the fossil record may be related to differential abilities of species to trigger biomineralization this calls for studies of the effective biomineralizing activity and fossilization potential of each species present in highly diverse natural microbial communities finally recent analytical developments leave little doubt that very substantial progress in the study of biomineralization processes and ancient biostructures will be achieved in the near future

magnetotactic bacterial abundance in pelagic marine environments is limited by organic carbon flux and availability of dissolved iron article i nfo article history magnetotactic bacteria intracellularly biomineralize magnetite of an ideal grain size for recording palaeomagnetic signals however bacterial magnetite has only been reported in a few pre quaternary records because progressive burial into anoxic diagenetic environments causes its dissolution deep sea carbonate sequences provide optimal environments for preserving bacterial magnetite due to low rates of organic carbon burial and expanded pore water redox zonations such sequences often do not become anoxic for tens to hundreds of metres below the seafloor nevertheless the biogeochemical factors that control magnetotactic bacterial populations in such settings are not well known we document the preservation of bacterial magnetite which dominates the palaeomagnetic signal throughout eocene pelagic carbonates from the southern kerguelen plateau southern ocean we provide evidence that iron fertilization associated with increased aeolian dust flux resulted in surface water eutrophication in the late eocene that controlled bacterial magnetite abundance via export of organic carbon to the seafloor increased flux of aeolian iron bearing phases also delivered iron to the seafloor some of which became bioavailable through iron reduction our results suggest that magnetotactic bacterial populations in pelagic settings depend crucially on particulate iron and organic carbon delivery to the seafloor

magnetic anisotropy magnetostatic interactions and identification of magnetofossils 1 single domain magnetite particles produced by magnetotactic bacteria mtb and aligned in chains called magnetosomes are potentially important recorders of paleomagnetic paleoenvironmental and paleolife signals rock magnetic properties related to the anisotropy of magnetosome chains have been widely used to identify fossilized magnetosomes magnetofossils preserved in geological materials however ambiguities exist when linking magnetic properties to the chain structure because of the complexity of chain integrity and magnetostatic interactions among magnetofossils that results from chain collapse during post depositional diagenesis in this paper magnetic properties of three sets of samples containing extracted magnetosomes of the culturedmagnetospirillum magneticumstrain amb 1 were analyzed to determine how chain integrity and particle concentration influence magnetic properties intact mtb and well dispersed magnetosome chains are characterized by strong magnetic anisotropy and weak magnetostatic interactions but progressive chain breakup and particle clumping significantly increase the degree of magnetostatic interaction this results in a change of the magnetic signature toward properties typical of interacting single domain particles i e a decrease of the ratio of anhysteretic remanent magnetization to the saturation isothermal remanent magnetization decreasing in the crossing point of the wohlfarth cisowski test and in the delta ratio between losses of field and zero field cooled remanent magnetization across the verwey transition as well as vertical broadening of the first order reversal curve distribution we propose a new diagram that summarizes the verwey transition properties with diagnostic limits for intact and collapsed chains of magnetosomes this diagram can be used in conjunction with other parameters to identify unoxidized magnetofossils in sediments and rocks

chains clumps and strings magnetofossil taphonomy with ferromagnetic resonance spectroscopy magnetotactic bacteria produce intracellular crystals of magnetite or greigite the properties of which have been shaped by evolution to maximize the magnetic moment per atom of iron intracellular bacterial magnetite therefore possesses traits amenable to detection by physical techniques typically narrow size and shape distributions single domain size and arrangement in linear chains and often crystal elongation past strategies for searching for bacterial magnetofossils using physical techniques have focused on identifying samples containing significant amounts of single domain magnetite or with narrow coercivity distributions searching for additional of traits would however increase the likelihood that candidate magnetofossils are truly of biological origin ferromagnetic resonance spectroscopy fmr is in theory capable of detecting the distinctive magnetic anisotropy produced by chain arrangement and crystal elongation here we present analyses of intact and lysed magnetotactic bacteria dilutions of synthetic magnetite and sedimentary samples of modern carbonates from the great bahama bank oligocene miocene deep sea muds from the south atlantic and pleistocene lacustrine deposits from mono basin california we demonstrate that fmr can distinguish between intact bacterial magnetite chains collapsed chains and linear strings of magnetite formed by physical processes we also show that sediments in which the magnetization is likely carried by bacterial magnetite have fmr spectra resembling those of intact or altered bacterial magnetite chains