simultaneous determination of alteration and eruption ages of volcanic rocks by electron spin resonance abstract the alteration and eruption ages of japanese welded tuffs were estimated by the method of esr using ge ohc and al centers in quartz whose stabilities are different the ages obtained from the ge and ohc centers were 1 2 ma however the ages from the al center varied from 0 059 to 1 36 ma the comparison of these ages with thermoluminescence tl and fission track ft ages proves that the esr age of the al center which agrees with the tl age shows the thermal history and in an ideal case gives the alteration age those of the ge and ohc centers which agree with ft age indicate the eruption age therefore this method enables us to describe the thermal history of a rock

esr dating of fault movement using various defect centres in quartz the case in the western south fossa magna japan the dates of movements of the itoigawa shizuoka tectonic line i s t l and minobu fault in the western south fossa magna have been obtained by esr dating measurements were made on various lattice defects of the ohc ge al and e centres in quartz grains of fault clay and quartz veins intruded at the time of movement all the dates obtained from these centres in quartz grains from two localities of the i s t l and iwo localities of the minobu fault fall in the range of 0 30 0 55 ma this suggests that all the centres were annihilated completely and that the obtained age can be admitted as the actual data of the latest fault movement meanwhile esr dates of quartz vein and fault clay in other localities locations 3 6 7 are divided into 0 30 0 55 ma and 1 5 2 0 ma which suggest incomplete resetting the dates of 0 30 0 55 and 1 5 2 0 ma might correspond to the clino unconformities observed in plio pleistocene sequence of this region

late pleistocene and holocene contourite drift in lake prespa albania f y r of macedonia greece hydro acoustic surveys and coring campaigns at lake prespa were carried out between 2007 and 2009 this paper presents hydro acoustic profiles and provide lithological and chronostratigraphical inf

comparison of esr ages of corals from marine terraces with 14c and 230th 234u ages the ages of corals from marine terraces in the ryukyu islands of japan have been determined by electron spin resonance esr esr ages deduced from the total dosage of natural radiation taking the time dependent dose rate due to 238 u series disequilibrium into account agreed fairly well with those determined by 14 c and 230 th 234 u dating the esr age can be extended well beyond the limits of 14 c dating 50 000 years and the 230 th 234 u method 300 000 years to a million years

interferences encountered in the determination of ad of mollusc samples inflexion points interfere with the radiation growth curve of the dating signal at g 2 0014 for mollusc samples several experiments give evidence that the definition of the dating signal at g 2 0014 has to be reconsidered a reliable ad determination very often seems questionable for esr dating of mollusc samples

correlation between roof and floor cumulates of the kiglapait intrusion labrador a successful correlation between floor and roof rocks is needed to study the effects of cooling rates on the nucleation solidification and trace element content of cumulate igneous rocks in felsic intrusions the most obvious assumption to test is that the core compositions of plagioclase feldspar correlate because the mineral is abundant and resistant to subsolidus exchange a test of that assumption is provided by the modal abundance of apatite which peaks near a plagioclase composition of an 38 in both floor and roof rocks of the kiglapait intrusion the test is made adequately sensitive by dividing the measured mode of apatite by an independently estimated residual porosity a procedure which helps correct for large amounts of trapped liquid that produced apatite in the roof rocks the procedure is applicable to other intrusions and its success here suggests that failures of correlation found elsewhere deserve another look

comment on m sarnthein h e stremme and a mangini the holstein interglaciation time stratigraphic position and correlation to stable isotope stratigraphy of deep sea sediments

u pb dating of a speleothem of quaternary age we demonstrate that u pb dating is a promising method for secondary carbonate materials of quaternary age and older by obtaining a 206pb 238u age for a speleothem with high u 10 g g 1 and very low pb 10 ng g 1 that is supported by an independent 230th age thermal ionisation mass spectrometry was used to determine the u and pb isotopic ratios and concentrations for subsamples of a stalactite from winnats head cave peak district uk we obtained 206pb 204pb ratios up to 50 and determined a 206pb 238u age of 248 10 ka which is within error of the 207pb 235u age of 333 79 ka and a spectrometric u th age of 255 ka for samples of tertiary and quaternary age the initial state of u series disequilibrium is an important consideration and as with most radiometric dating techniques the mineral must have remained closed to u th pb and all intermediate daughters we show that dense calcite speleothems are ideal in this respect and that no loss of rn has occurred unlike u series disequilibrium methods u pb dating has no upper limit and hence materials of quaternary age older than 0 6 ma can be analysed to investigate landscape development paleoclimate hominid evolution or hydrogeochemistry in carbonate terrains

uranium series dating of molluscs from uplifted holocene beaches in the persian gulf the study of coastal deformation and sea level history calls for radiometric ages on shorelines older than the past 20 000 yr the period for which reliable 14c ages can be obtained uranium series disequilibrium methods have yielded the requisite ages for reef coral ranging from 5 000 to 300 000 yr but previously have proved unreliable for most molluscs the major source of uncertainty being postmortem migration of uranium and its daughter radionuclides into and out of the shells in the present study the 230th 234u dating method1 was applied to molluscs from holocene beaches in the persian gulf which had been removed from marine influence by seismic uplift two specimens selected for comparative dating with the electron spin resonance esr method yielded ages of the correct order of magnitude excellent agreement was obtained between 14c and 230th 234u ages after detrital effects were corrected for by reference to modern comparative material for both calcitic and aragonitic specimens which suggests that uranium series dating of pre holocene molluscs may give reliable results provided the depositional history of the shoreline is well documented

further studies on the use of quartz grains from fault gouges to establish the age of faulting abstract quartz grains were selected from samples of intrafauit material at two outcrop sites of the atotsugawa fault in central japan surface textures of the grains observed by scanning electron microscope were classified into texture groups i iv in the order from a simple feature through increasing undulations to a texture with cavities the defects in the quartz measured by electron spin resonance gave absolute ages using the grains the relative ages by surface texture groups were tentatively correlated to the absolute ages as determined by the electron spin resonance it was disclosed that subgroups ia and ib were stable during the period of 0 9 ma and changed through intermediate subgroup ic in a period ranging from 0 9 to 1 2 ma and then to group ii after 1 2 ma therefore the surface texture groups can change from subgroups ia and ib through intermediate subgroup ic to group ii with increasing age this indicates that the surface texture groups of quartz grains in the fault are effective for dating fault activity concisely

esr dating of the fossil hominid cranium from petralona cave greece the age of the hominid cranium discovered in 1960 in a limestone cave near petralona greece is a continuing cause of controversy the age of the skull which was apparently encrusted by brown calcite soon after the death of the individual concerned has been variously estimated at between 70 0001 and 700 0002 yr here we show using electron spin resonance esr measurements of the calcite encrustation and of bone fragments that the age of the petralona hominid lies between 160 000 and 240 000 yr we also demonstrate by trace element analysis that the composition of the calcite encrustation is the same as that of the very top of the travertine floor

esr dating in quaternary geology abstract electron spin resonance esr a relatively new dating technique was first suggested by zeller et al 1967 zeller 1968 and levy 1968 it has made substantial progress in frequent applications in the last few years esr dating is based on the direct measurement of the amount of radiation induced paramagnetic electrons trapped in crystal defects these free electrons were generated by alpha beta and gamma radiation of natural radioelements e g u th k and have accumulated in the minerals over geologic time the esr age is obtained by dividing the total amount of accumulated radiation dose archaeological dose ad by the dose per year annual dose this review comprises four major parts the principles of the method the determination of the archaeological dose ad the determination of the annual dose and a compilation of datable materials several questions remain the evaluation of the ad the determination of the annual dose and particularly with respect to the nature and stability of the electron traps used for dating

geochronology of early human settlements in java what is at stake abstract despite the fact java island is a volcanic area it has been challenging to build a chronological framework of its early human settlements from the oldest lower pleistocene homo erectus up to the dispersals that followed the last glacial maximum lgm various dating methods are implemented on volcanic effluents sedimentary deposits speleothems and also on fossils including direct analyses on human remains thanks to radiometric and palaeodosimetric grounded techniques as well as to magnetostratigraphy however a number of results must be considered with caution in order to identify specific bias originating from reworking of volcanic effluents or post depositional geochemical evolution such bias might well explain apparent contradictions between absolute dating results and other chronologically significant proxies e g biostratigraphy converging age estimates resulting from the implementation of several dating methods though being sometimes less precise seem to have a higher reliability

the holstein interglaciation time stratigraphic position and correlation to stable isotope stratigraphy of deep sea sediments marine molluscan shells from para type and other loclities of the holsteinian interglaciation were dated by thu and the electron spin resonance esr method to more than 350 000 and 370 000 yr b p beyond the limit of thu dating the high age estimate is corroborated by a kar age of 420 000 yr b p determined from volcanic ash near the base of the ariendorf paleosol in the middle rhine valley believed to be a pedostratigraphic equivalent of the holsteinian shells from the herzeele marine unit iii an equivalent of the wacken domnitz warm stage in northern france and subsequent to the holsteinian revealed ages between 300 000 and 350 000 yr b p a correlation of these two warm stages with marine oxygen isotope stages 11 and 9 on the specmap and cartune time scales is suggested from the benthic oxygen isotope record one may infer that no exceptionally high global sea level rise corresponds to the large transgressions of the holstein sea in northern germany therefore a significant proportion of the transgression was probably the result of an unusually large local glacial isostatic depression caused by the extreme buildup of ice during the preceding elster glaciation stage 12 according to the deep sea record it lasted approximately 50 longer than the subsequent cold stage 10 the outstanding soil formation with braunlehm and the well developed thermal optimum of the holsteinian are tentatively related to a phase of minimum sea ice cover in the norwegian greenland sea as deduced from long benthic carbon isotope records from the central atlantic

dating of fossil shells with electron spin resonance electron spin resonance esr dating of sea shells has been made using the paramagnetic defects produced by natural radiation the total dose of natural radiation of the materials termed the archaeological dose has been determined from esr signals of defects in sea shells from northern japan whose ages are known from the sediments or from the radioisotope dating an annual dose of about 0 03 0 04 rad yr explains the age of shells from a few thousand to a million years the new method of esr dating will be useful for sediment age determination and for other geological studies

the system fayalite albite anorthite and the syenite problem the presence in a magma of fayalite the iron end member of the olivine binary series affects the feldspars at pressure by lowering the temperatures at which they crystallize from the magma starting with estimates from published literature it becomes obvious that at pressure fayalite becomes important because the pressure effects on the melting temperatures are very different large for albite and small for anorthite in this experimental study a powder of fayalite composition was combined with six finely ground natural feldspars from ab to an 97 to make six bulk compositions using graphite crucibles in piston cylinder apparatus at a pressure of 5 kbar a cotectic in the ternary system was found to range from 1141 c at an fa to 1124 c at ab fa with fayalite contents from 68 to 17 wt respectively the results can be used to show that ternary feldspars saturated with fayalite and fe monoclinic pyroxene will crystallize at a 5 kbar multiphase eutectic 1010 c 56 c below a calculated azeotropic point on the ab or join the results are used to compare the end points of two very different layered intrusions skaergaard and kiglapait and to illuminate the nature and origins of syenite and trachyte which are leucocratic rocks unsaturated with mafic minerals because fayalite saturated melts are responsive to pressure unequally on the feldspar end members olivine of intermediate composition will have a damped but potentially significant effect on feldspar fractionation in the lower crust of the earth possibly affecting the origin of anorthosite and syenite

esr dating of planktonic foraminifera isotopic and palaeontological studies on quaternary deep sea sediment have provided relative but well established time scales with ages mostly calibrated from the magnetic polarity time scale absolute dating techniques such as u series or k ar dating have also been successful however difficulties exist such as elemental concentrations near the detection limit or a lack of the necessary minerals i report here on electron spin resonance esr dating of marine cores which utilizes the damage caused by natural radiation in planktonic foraminifera an esr signal grows linearly with the irradiation dose it is found that the total radiation doses in the foraminifera increase with depth in two cores studied the results demonstrate the viability of esr dating for planktonic foraminifera up to 1 myr in age

uranium series age determination of travertines from the site of vertesszollos hungary abstract the site of vertesszollos has yielded a pebble tool industry a fragment of the cranium of a primitive form of homo sapiens and a vertebrate fauna indicative of the biharian faunal stage we have analyzed the travertines under and overlying the hominid bearing marl all the samples are significantly contaminated with detritus so that calculated u series disequilibrium ages provide upper limits to the true age the individual samples when corrected for a possible initial 230 th 232 th ratio of 1 5 give an average age of 211 13 ky by fitting the data to a model consisting of a mixture of authigenic and detrital components we obtain an age of 162 62 73 ky the travertines appear to have been deposited over a span of about 40 000 years centred at about 185 25 ky bp this places their deposition near the beginning of isotope stage 6 much younger than has been generally believed

shock induced devolatilization of calcite the amounts of co 2 and co evolved upon shock compression and decompression of calcite to 18 gpa 180 kbar have been determined using a new gas phase shock recovery technique and gas source mass spectrometry the data demonstrate that from 0 03 to 0 3 mole percent of calcite is devolatilized at shock pressures significantly lower than those predicted 30 gpa for the onset of volatilization by continuum thermodynamic theory and are in qualitative agreement with release adiabat data for calcite and aragonite carbon and oxygen isotope ratios in the shock released co 2 are the same as those in the unshocked hydrothermal calcite demonstrating that the co 2 comes from the calcite rather than other potential sources

testing for pb isotopic differences between minerals in the kiglapait layered intrusion by la icp ms abstract mineral scale pb isotopic variations in cumulates of the kiglapait intrusion the largest troctolitic intrusion of the proterozoic nain plutonic suite in labrador canada are evaluated directly in thin section by single spot la icp ms analysis of minerals with low pb concentrations e g plagioclase 0 31 3 3 ppm clinopyroxene 0 06 1 1 ppm at high spatial resolution

quaternary glaciations recorded by glacial and fluvial landforms in the shaluli mountains southeastern tibetan plateau abstract the shaluli mountains a tectonically controlled mountain range between the jinsha and yalong river rifts are located in southeastern tibetan plateau in the central shaluli mountains an ice cap of 3600 km 2 once developed on the haizi shan abundant glacial landforms are present on the haizi shan and in the surrounding river valleys together with the outwash terraces in the yazheku river the northeastern part of the haizi shan provides an ideal site to examine the quaternary glacial history of the region sedimentological and morphostratigraphical analysis field mapping and dating by electron spin resonance esr define at least seven major glacier advances in the haizi shan area six major glacier advances likely occurred during marine oxygen isotope stage mis 16 mis 14 12 mis 6 mis 3 early mis 2 and the global last glacial maximum these can be defined on the basis of esr dating and stratigraphical analysis of the glacial landforms in front of the kuzhaori glacial trough on the southern slope of the haizi shan the outwash terraces in the yazheku river also record four major glacier advances which occurred during mis 16 mis 12 mis 6 and mis 2 in addition the moraines preserved on the southwestern part of the haizi shan suggest that a glacial advance likely occurring during the lateglacial the extent of glaciation on the haizi shan decreased with time

kiglapait mineralogy iv the augite series based on twenty five new chemical analyses augites from the upper zone of the kiglapait layered intrusion labrador span the range from en 7 3 to en 0 disposed about a straight line sloping slightly upward from wo 4 0 to wo 4 2 in the pyroxene quadrilateral they contain little tetrahedral al which decreases with fe enrichment as tetrahedral ferric fe 3 increases little or no jadeite or ca tschermaks component is present titanium rises only slightly with fe and the acmite component is scattered near mole fraction 0 03 excess cations relative to 6 oxygen atoms occur chiefly by solid solution toward olivine the only co crystallizing mafic silicate phase values of n increase linearly over the range 1 670 at fictive en 1 0 0 to 1 7448 at en 0 the position of the 150 powder x ray diffraction peak shifts regularly from 5 0372 to 4 1727 degrees away from the 220 peak of silicon metal over the same composition range exsolution of orthopyroxene near 100 is succeeded up stratigraphy by that of pigeonite near 001 and the switch occurs at about the same augite composition as the switch from external orthopyroxene to pigeonite in the skaergaard intrusion exsolution of ilmenite in or near 100 and magnetite ulvospinel near the a and c directions in 010 produces the black color of these augites in hand specimen subsolidus augite olivine tie lines and exchange relations in fe mg allow the distinction between equilibrium pairs and those affected by exchange with external fe ti oxide minerals or with intercumulus liquid in upper border zone lithologies liquids producing augite and olivine with plagioclase follow a ca depletion trend until crystallization of abundant olivine and titanomagnetite drives them on a ca enrichment trend to a point near mg free augite activities of silica consistent with augite olivine pairs range from 0 6 to 0 98 the kiglapait augite series exemplifies the crystallization of a magma occupying the narrow regime between silica saturation and undersaturation in extreme fractionation from troctolite to mg free syenite

plagioclase fractionation in troctolitic magma troctolitic intrusive rocks poor in augite are common in certain proterozoic anorthosite complexes and related rocks the lower zone of the kiglapait intrusion labrador consists of 1570 km troctolite today and possibly 2900 km before erosion in this augite free lower zone plagioclase fractionation is as low as 1 6 an km of cumulate thickness and averages 3 an km when augite crystallizes after 84 of the magma has crystallized the fractionation becomes as much as 17 an km of cumulate why such a difference it is clear from first principles of phase equilibria that fractionation accelerates with saturation in augite but not so clear that the difference should be so great the answer is to be found in the silica poor nature of troctolitic magma that is critically undersaturated in silica this low silica effect reduces the activity of the nasi albite component relative to the caal anorthite component in the plagioclase thereby favoring the an component of the liquid and crystals and weakening the fractionation process as the normative augite component in the magma rises from the base of the lower zone to the base of the upper zone the activity of silica also rises slightly and its consequent effect on plagioclase composition tends to diminish liquid fractionation paths derived from observed crystal paths when plotted in the system diopside anorthite albite rise across the liquidus fractionation lines toward diopside and reach augite saturation near the 1atm cotectic they produce plagioclase compositions 10 mol higher in an than pure liquidus fractionation lines predict the key criterion for the troctolitic fractionation of plagioclase composition is the absence of ca poor pyroxene from the rocks noritic magmas by contrast have higher activities of silica and more effective fractionation of plagioclase a parallel fractionation of olivine is also retarded in the lower zone by the accumulation of ferric iron in the liquid until augite and titanomagnetite crystallize in the upper zone key word plagioclase fractionation troctolite melts silica activity layered intrusions kiglapait intrusion

esr dating of glacial tills and glaciations in the urumqi river headwaters tianshan mountains china abstract electron spin resonance esr dating of the shangwangfeng the xiawangfeng and the gaowangfeng tills in the headwaters of the urumqi river was carried out using ge centers in quartz grains the shangwangfeng till is dated at 35 3 5 ka bp three dates from the lower portion of the xiawangfeng till are 171 1 17 176 18 and 184 7 18 ka bp respectively and the age of the gaowangfeng till is 459 7 46 ka bp considering the available ages i e 14 c tl and esr and the principles of geomorphology and stratigraphy the shangwangfeng till is determined to be deposited in marine isotopic stage 2 3 mis2 3 the upper part of the xiawangfeng till was formed in mis4 and the lower part was deposited in mis6 the gaowangfang till is the oldest at the head of the urumqi river corresponding to mis12 the age of the gaowangfang till also demonstrates that the tianshan mountains lay at a suitable altitude for a glacial climate at that time when the glaciers on this segment of the mountain began to develop

esr dating studies of palaeo debris flow deposits in dongchuan yunnan province china abstract the ages of palaeo debris flow deposits in dongchuan yunnan province were determined by esr dating they are consistent with a 14 c age estimate the results suggest that the debris flow deposits were formed during humid periods of the late pleistocene simulation experiments and sem analysis show that the resetting of ge centres in quartz is most likely due to collisions of the quartz grains during the process of rapid deposition

uplift caused by lithospheric flexure in the hawaiian archipelago as revealed by elevated coral deposits the presence of definitive indicators of sea level such as corals found in growth position coralline beach deposits wave cut notches and wave eroded terraces all at elevations above known levels of eustatic sea level during the past 500 ka provides strong evidence that uplift has occurred in the central high hawaiian islands lithospheric flexure is proposed as the mechanism for uplift the modelled wavelength and amplitude of flexure roughly correspond to the distance and height of elevated coral rich deposits a trend of increasing age of coralline beach deposits with elevation on oahu and molokai adds support to the uplift hypothesis data and observations presented in this paper are inconsistent with a tsunami origin for most elevated deposits on lanai molokai and oahu a giant wave origin may only apply to scattered and localized deposits concentrated in low lying gulches 100 m such as those on lanai

description and esr dating of the holsteinian interglaciation abstract the classical region of the holsteinian interglacial is in the vicinity of hamburg and the lower elbe it is defined on the basis of pollen and is clearly distinguishable from the eemian interglacial hallik 1960 muller 1974 the holsteinian interglacial is represented by a sequence of sediments up to 100 m in thickness these consist of limnic fluvial and marine beds and show a transgression up to the height of present sea level twenty seven molluscs from holsteinian deposits were used for esr dating the ages show that the holsteinian may be correlated with stage 7 of the deep sea record v28 238 shackleton and opdyke 1973

esr dating of quaternary shells recent advances abstract this paper deals with the key problems of the esr dating of subfossil mollusc shells the estimation of the stored palaeodose of natural radiation it is shown that the use of the analytical line or peak in the integrated spectrum at g 2 0012 0 0001 with the half width 0 6 mt seems most advisable for the estimation of the relative concentration of radiation defects equivalent to the stored palaeodose in the calcareous shell skeleton optimal esr spectrometer settings have been determined results of esr dating of subfossil mollusc shells from eemian deposits of boreal transgression are discussed

experimental equilibrium tested by plagioclase loop widths are solid and liquid respectively and an is the mole fraction or per cent an an ab it is measured from the plagioclase composition and an estimate of the liquid composition based on standard assumptions rooted in the norm recalculation routine a survey of a large new database allows study of the 1 atm experimental literature involving 819 experiments the approach to equilibrium is tested empirically by the loop width and its transform the linear partitioning function kd this function is the exchange coefficient formed as the intercept at pure an s from the array over all x s of the partition coefficient d when defined as x s x l w herex is the mole fraction d and kd are thus limited to lie between zero and 1 0 the results show a 1atm loop width ranging from 0 2t o 68 mol a n with associated kd 0 03 0 98 these extrema represent loops both far too small and far too large to represent stable equilibrium between plagioclase and liquid some of the higher values lie near the persodic limit because the an component of the liquid is scarce and the liquid composition is ab rich the loops from ne normative liquids span the range from 40 to 90 mol an in the crystal with loops 2 50 mol wide a baseline for loop width is derived from the precise synthetic study of the system di an ab at 1atm and an array of high pressure data that extrapolates to the same value of kd 0 26 at 1atm many of the 1atm experimental data fall far outside any reasonable uncertainty limits on the baseline causes of departure include crystal disequilibrium that can lead to errors in both directions and compositional problems comparison of the values of kd with liquid compositions in silica oxygen fugacity temperature kinetics and sodium reveals the common presence of sodium deficiency a crystallinity study shows a definite decrease in sodium content with liquid evolution whereas the sodium content should increase or at least remain nearly constant with evolution of the melt a selection of self consistent 1atm data from a few laboratories shows a close correspondence to the standard distribution of loop widths and indeed most literature data lie within the limited range of kd 0 26 0 4 experiments known to be hydrous show very low values of kd and corresponding large loop widths as previously understood from literature data when data limited to nearbaseline kd values are plotted against temperature they yield expected thermal slopes and concave up curves of temperature plotted against plagioclase composition literature data show a positive correlation of kd with dry pressure and a separate database from 2 to 15 kbar shows that more than half the data comport with this pressure effect a different group ranges down to kd as low as 0 2 with increasing loop widths some of these are alkalic and hence rich in the ab component of the liquid others were obtained in fe containers that control the oxygen fugacity to low values and convert the fayalite component of the liquid to iron oxygen and silica this reaction increases the activity of silica and in turn the activity of ab in the melt thus widening the loop thermodynamic studies concerned with plagioclase melt equilibria will profit from an awareness of these effects

mineral compositional constraints on petrogenesis and oxide ore genesis of the late permian panzhihua layered gabbroic intrusion sw china a systematic study of mineral compositions has been carried out on stratigraphic sections through the panzhihua intrusion a layered gabbroic sill of late permian age that hosts significant magmatic fe ti v oxide deposits in the emeishan large igneous province sw china the intrusion which is 19 km long and 2 km thick is divided into a marginal zone mgz lower zone lz middle zone sub zones mza and mzb and upper zone uz from the base upwards compositions of the most primitive cumulus olivine fo81 and plagioclase an73 found in the intrusion suggest that the parental magma was similar to the mg rich end member of the coeval high ti basalts in the region two reversals in terms of mineral compositions are found in the intrusion one in the lower mza and the other at the transition between the mzb and the uz the first reversal is marked by a gradual increase in the an content of plagioclase an60 to an70 over a 100 m vertical interval the other is characterized by abrupt changes in the compositions of olivine fo28 to fo70 clinopyroxene mg 51 to 75 and plagioclase an24 to an51 over a 20 m vertical interval these suggest that the panzhihua intrusion opened at least twice for recharge of more primitive magmas strong depletion of incompatible trace elements such as zr in the cumulate sequence without corresponding enrichment in any border series is suggested to be evidence for significant loss of residual liquid at a late stage during solidification of the intrusion compared to other well studied layered intrusions the panzhihua intrusion contains fe ti oxides crystallized at a high temperature consistent with evidence obtained in earlier studies early appearance of liquidus fe ti oxides in the panzhihua magma is most likely a combined effect of a rather high degree of initial oxidation and elevated volatile fugacity

principles of applied experimental igneous petrology a comment on experimental constraints on the skaergaard liquid line of descent by thy lesher nielsen and brooks 2006 lithos 92 154 180 abstract the foremost principles of experimental igneous petrology applied to natural rocks are here considered to be the following first only the mineral assemblages found at or near the experimental liquidus are relevant to fractional crystallization subliquidus assemblages of the same bulk composition can have little relevance to this process owing to the closed system of the experiment second in a closed system the natural mineral assemblages define the intensive parameters of t p and the activities of all components including oxygen which must constrain the experimental investigation extensive mass dependent parameters do not define the compositions of the evolving liquids which are solely controlled by successive liquidus phase assemblages third the bulk compositions rocks or mixtures chosen for study must be able to yield at the liquidus the mineral compositions found in the natural occurrence the study under discussion fails in all three of these desiderata subliquidus products of equilibrium crystallization and their masses were used to infer a differentiation history intensive parameters were constrained to an arbitrary choice of the fmq buffer finally the bulk compositions chosen for experiment can be shown beforehand and as in the listed results to yield olivine and plagioclase compositions far more refractory than in any known rock of the target intrusion

the incision variations of poiqu documented by the zhangmu landslide in the upper himalaya of tibet abstract aiming at the rate and causes of the incision variations in the upper himalaya orogenic belt of tibet a new method of incision rate estimation based on the analysis of the evolution of zhangmu landslide and its spatial and temporal relationship with the surrounding gullies is applied the research results are 1 the zhangmu landslide was an ancient huge landslide occurred at 24 2 2 4 ka bp consisting of an ancient bedrock landslide and subsequent deposit landslides with an area of 1 23 km2 and remaining volume of 23 4 106 m3 2 the fluvial incision rate shows variations in poiqu and its branch which may be controlled by the discharge and decreases from the poiqu 11 5 1 2 mm a to the tributaries from 4 8 0 5 mm a in the bangcundong gully to 2 4 0 2 mm a in zhangmu gully 3 the fluvial incision rate also shows temporal variations in the poiqu there are two periods of low rate and high rate incision processes in the poiqu while the section shape transforms from a gentle slope to a cliff in the low rate period from 24 2 ka bp to 10 0 ka bp in the poiqu valley the incision rate was 10 4 1 0 mm a while the high fluvial incision rate since 10 0 ka bp was 13 0 1 3 mm a 4 the fluvial incision promotes the landscape evolution and triggers the potential landslide in thousands of years

electron spin resonance dating of the pleistocene coral reef tracts of barbados abstract the reef tracts of barbados have been investigated by electron spin resonance dating all parameters necessary for esr dating including effective efficiency and thermal stability were determined without cross checking with another independent dating method in addition some u series analyses were carried out in order to test the reliability of esr in most cases the results show a satisfactory agreement between esr and both these and previously published u series dates m l bender r g fairbanks f w taylor r k matthews j g goddard and w s broecker 1979 geological society of america bulletin 90 577 594 for the oldest samples esr dates tend to exceed he u dates suggesting that there might have been he loss from aragonite raised reef tracts are assigned to high sea stands from successive interglacial stages 5 7 9 11 13 and 15 esr and u series 230th 234u dates for corals and molluses in north barbados do not support the suggestion of n p james 1971 unpublished thesis mcgill university montreal that this region has subsided during part of the past 125 000 yr whereas the experimentally determined mean life of trapped electrons is only 500 000 yr for the ambient temperature in barbados there is no evidence from the comparison between esr and other dates for thermal fading this emphasizes the difficulty of experimental measurement of

crystallization sequence and magma chamber processes in the ferrobasaltic sept iles layered intrusion canada the sept iles layered intrusion quebec canada 564 ma is a large plutonic body with a diameter of 80 km and a thickness of 6 km made up from its base to top of a layered series with troctolite and gabbro and an upper border series with anorthosite capped by cupolas of a type granite chilled margin compositions suggest a ferrobasaltic parental magma close to that of the skaergaard intrusion but much richer in iron and titanium samples from drill cores and surface sampling of the 4 7 km thick layered series reveal a succession of massive troctolites and layered gabbros that contain 24 fe ti oxide layers cm to m thick and many anorthositic autolithic blocks the sequence of crystallization in the layered series is plagioclase an72 34 and olivine fo75 21 followed by magnetite and ilmenite then ca rich pyroxene and finally apatite an olivine gap is observed between fo66 and fo59 the saturation of fe ti oxides before ca rich pyroxene is interpreted to be the result of the high feot and tio2 contents and the low cao content of the parental magma contamination by old continental crust has occurred during crystallization of the layered series as indicated by sr isotopic compositions 87sr 86sr564 0 70360 0 70497 the differentiation trend of the intrusion is interrupted by two large and many small reversals to more primitive compositions of cumulus phases cr content of magnetite and lower sr isotope ratios these reversals and the intermittent disappearance of some phases are interpreted as resulting from magma chamber replenishments by undifferentiated primitive basaltic magma and mixing with the resident magma the author 2010 published by oxford university press all rights reserved for permissions please e mail journals permissions oxfordjournals org

the lower acheulian site of ambrona soria spain ages derived from a combined esr u series model abstract the lower paleolithic sites of ambrona and torralba soria spain are often associated with each other because of their proximity although they do not represent the same morphostratigraphic unit systematic and extensive excavations were conducted at these sites by an american team during the 1960s and 1980s recently 1989 2000 a spanish team has reactivated the research by initiating a new interdisciplinary project in the central sector and west of the ambrona site a stratigraphy has been established with six units from as1 at the base to as6 at the surface corresponding to fluvial lacustrine deposits in which abundant fauna associated with acheulian artefacts were found the most abundant species were elephant horse deer and aurochs other species like carnivores occur in small numbers only the lithic assemblage is relatively sparse and consists of a few bifaces choppers and several flake tools distributed throughout levels as1 to as5 the fauna and the lithic industry therefore document human presence at ambrona during the middle pleistocene in order to verify the presumed antiquity of the ambrona deposits horse teeth sampled in levels as1 as2 and as6 were analysed using combined esr u series us methods the samples from the lower levels as1 and as2 underwent a very recent uranium uptake as indicated by the u series dates ranging between 5 and 18 ka in contrast a more conventional postmortem uranium uptake was observed in the upper level samples as6 in the enamel and dentine tissues while a light u leaching was observed in the cementum the combined esr u series dates obtained on these samples suggest a minimum age of approximately 350 ka contemporaneous of osi 9 or the end of osi 11 for the ambrona site

resetting experiment of e centres by natural faulting the case of the nojima earthquake fault in japan abstract the resetting state of e centres in quartz in fault clay gouge has been examined using the nojima earthquake fault that moved during the southern hyogo prefecture earthquake in 1995 as a result the e centres have never been reset by this faulting event furthermore there is no regular tendency among the d e values obtained from the grain samples and the plateau region of the esr ages does not exist in the case of the nojima fault therefore it is not possible to judge the complete resetting of esr signals by natural faulting on the other hand the increase of radiation sensitivity of the e centres may be ascribed to the formation of the precursors by rays emitted from the radioactive elements adhered around the grain samples since the adherence of the radioactive elements may begin with fracturing the quartz grains by faulting the esr ages obtained from the unsaturated e centres with high radiation sensitivity may give the age of beginning of the fault movements the esr ages obtained from these unsaturated e centres of the nojima fault 0 88 0 3 ma 1 51 0 51 ma or 1 07 0 36 ma 1 75 0 59 ma are consistent with the geological age estimate of the beginning of the fault movements

early human occupation at devil s lair southwestern australia 50 000 years ago abstract new dating confirms that people occupied the australian continent before the earliest time inferred from conventional radiocarbon analysis many of the new ages were obtained by accelerator mass spectrometry 14c dating after an acid base acid pretreatment with bulk combustion aba bc or after a newly developed acid base wet oxidation pretreatment with stepped combustion abox sc the samples charcoal came from the earliest occupation levels of the devil s lair site in southwestern western australia initial occupation of this site was previously dated 35 000 14c yr b p whereas the aba bc ages are indistinguishable from background beyond 42 000 14c yr b p the abox sc ages are in stratigraphic order to 55 000 14c yr b p the abox sc chronology suggests that people were in the area by 48 000 cal yr b p optically stimulated luminescence osl electron spin resonance esr ages u series dating of flowstones and 14c dating of emu eggshell carbonate are in agreement with the abox sc 14c chronology these results based on four independent techniques reinforce arguments for early colonization of the australian continent

esr dating of pleistocene fossil teeth from alberta and saskatchewan teeth collected from pleistocene surficial sediments in southeastern alberta and western saskatchewan have been dated by electron spin resonance esr the dates generally agree with the previously

esr dating of fault gouge the effect of grain size abstract esr signals of quartz grains in fault gouge have been partially or completely reset by movements on the fault which allows the dating of the last fault movement in order to better understand the zeroing process we have studied the variation in esr signal ad and age in various grain sizes since it can be expected that larger grains will be less affected by stress than smaller grains we propose that a plateau of constant lower age for the smallest grains indicates total resetting this is confirmed in gouge from a fault in california only such samples should be used for dating

application of electron spin resonance esr dating to ductile shearing examples from the qinling orogenic belt china abstract shear zones are common structures in orogenic belts and elucidation of the tectonic evolution of these orogenic belts to a large degree depends on understanding the kinematics and timing of shear deformation however there is a lack of an accurate fast and convenient way to determine the timing of deformation in this paper we apply the esr electron spin resonance spectroscopy dating method to three syntectonic quartz veins from the funiushan tectonic belt in the qinling orogenic belt in central china the results agree well with the available ages of deformation in the area obtained through other dating methods this demonstrates the accuracy and feasibility of using the esr method to date quartz crystals formed during deformation the method is fast and convenient and satisfies the accuracy requirement it is an effective means for determining the timing of deformation especially in areas with intensive fluid activity during deformation

new dates for the tata hungary archaeological site the archaeological site at tata 70 km wnw of budapest has yielded a mousterian lithic industry of small artefacts chipped from chert pebbles with affinity to the quina type1 however the two best known artefacts from the site are a churinga carved from a piece of a mammoth tooth fig 1 and an amulet with an inscribed cross made on a polished nummulite fossil marshack personal communication who examined both the churinga and nummulite observed that one or both arms of the cross engraved on the nummulite are in fact natural fractures that penetrate through the stone however the ivory plaque appears to have been carefully separated from a compound molar tooth of a mammoth shaped and bevelled and then coloured red by rubbing with ochre the age of this site was first determined by 14c analysis of charcoal from the cultural layer2 the age of 55 2 5 kyr led bordes to assign the cultural material to the middle mousterian however palaeontological data3 indicate that this site was occupied towards the end of the last interglacial also two single determinations of th u ages on travertines from the site yielded dates of 116 16 kyr ref 4 and 70 20 kyr ref 5 both of which are more consistent with present estimates of the time interval corresponding to the last interglacial 125 90 kyr we report here new uranium series dates on the travertine which show that the site was occupied at 100 kyr bp this confirms that the amulet from this site is one of the oldest decorative artefacts known and was presumably created by homo sapiens neanderthalensis

esr dating of spring deposited travertines abstract esr dating of spring deposited travertines is complicated by the presence of acid insoluble minerals which contain concentrations of radioactive elements that differ from those of the secondary calcite which is to be dated and the fact that most samples do not display esr signals which are suitable for dating however sampling of synsedimentarily formed crusts significantly increases the probability that the esr spectrum of the samples contains the signal at g 2 0007 which can be used for a dating attempt additionally the concentration of acid insoluble minerals in those crusts is normally negligible

esr dating of the sediments of the last glaciation at the source area of the urumqi river tian shan mountains china abstract electron spin resonance esr dates were obtained from glacial quartz sands formed during the last glaciation at the source area of the urumqi river tian shan mountains northwestern china esr dating of a basal till interpreted as a subglacial melt out till deposited in an end moraine which was produced in the late stage of the last glaciation is consistent with ages determined through the ams 14c method however dating of the overlying sediment interpreted as supraglacial melt out till associated with the same moraine produced a result that differs from that determined using the ams 14c method subglacial comminution could reset the esr signal thus making esr dating of basal till possible the lower wangfeng group formerly of controversial age was formed ca 50 70 ka during the early stage of the last glaciation it was deposited throughout the main valley as low as 2300 m a s l over a length in excess of 19 km fluvial sandy gravel was deposited in the interstadial between the early and late stages of the last glaciation

the distribution of 230th234u ages in corals and the number of last interglacial high sea stands abstract the 104 available 230 th 234 u analyses of unrecrystallized corals from stable emerged terraces indicate that the last interglacial period occurred approximately 125 000 yr ago an estimate is made of the exact duration of this period by accounting for the surprisingly small distribution width observed among the 80 most reliable analyses this distribution width is compared with those obtained for model populations generated by assuming various characteristic analytical errors and various lengths of the last interglacial period the results show that 1 if there was only a single rise in sea level it probably lasted no more than 12 000 yr in agreement with previous estimates and 2 if there were two separate rises of sea level the gap between them must have been less than 7500 yr and not 12 200 as proposed by some authors

a reassessment of the age of the fauna from cumberland bone cave maryland middle pleistocene using coupled u series and electron spin resonance dating esr

kiglapait mineralogy iii olivine compositions and rayleigh fractionation models olivints present throughout the layered cumulates of the kiglapait intrusion record extreme iron enrichment during fractional crystallization mn is less compatible than fe the exchange coefficient kd for mn fe ol liq has values near 0 95 but they drop to 0 7 near the lower one upper one boundary ca is depleted by more than a factor of 30 relative to experimental values at 5 kbar pressure attempts to find a sink for ca in the lower zone without invoking liquid as a reactant are unconvincing and questions of metastability arise cumulus olivines vary systematically to lower fo contents with stratigraphic height using equilibrium values for the exchange coefficient kd fe mg ol ljq j and the observed mode of olivine and residual porosity a rayleigh fractionation calculation reproduces the observed lower zone trend without recourse to multiple injections of magma an anomalously fe rich region above the main ore band in the upper zone ascribed to ponding of fe rich magma at the floor of the intrusion until later buoyant residual magma entrained the fe rich residua such fe rich ponds probably account for the abnormal fe enrichment shown by some other fenner trend layered intrusions summation over the observed crystal compositions yields values of xjug that do not represent the equilibrium liquid but that reduce to it by a simple multiplier p 0 78 this result means that if ko is known the high temperature liquidus olivine compositions can be retrieved or vice versa because the observed olivine compositions are supported by realistic forward models there is no need to invoke evolved boundary layer liquids to explain the in situ crystallization of kiglapait cumulates classical cumulate theory suffices

potential and limits of combining studies of coarse and fine grained sediments for the coastal event history of a caribbean carbonate environment the coastal deposits of bonaire leeward antilles are among the most studied archives for extreme wave events ewes in the caribbean here we present more than 400 electron spin resonance esr and radiocarbon data on coarse clast deposits from bonaire s eastern and western coasts the chronological data are compared to the occurrence and age of fine grained extremewave deposits detected in lagoons and floodplains both approaches are aimed at the identification of ewes the differentiation between extraordinary storms and tsunamis improving reconstructions of the coastal evolution and establishing a geochronological framework for the events although the combination of different methods and archives contributes to a better understanding of the interplay of coastal and archive related processes insufficient separation superimposition or burying of coarse clast deposits and restricted dating accuracy limit the use of both fine grained and coarse clast geoarchives to unravel decadal to centennial scale events at several locations distinct landforms are attributed to different coastal flooding events interpreted to be of tsunamigenic origin coastal landforms on the western coast have significantly been influenced by sub recent hurricanes indicating that formation of the coarse clast deposits on the eastern coast is likely to be related to past events of higher energy

dominant influence of volcanic loading on vertical motions of the hawaiian islands abstract rates of island vertical motion above intra plate hotspots record the processes that arise from interactions between lithospheric plates and mantle plumes to assess the contribution of mantle and lithospheric processes to surface motion above the hawaiian hotspot we compare simple models of lithospheric deformation to vertical motion rates measured from dated paleoshorelines and tide gauge records in the hawaiian islands our analysis shows that observed uplift and subsidence rates mainly record the flexural response of the lithosphere to volcanic loads the effective elastic plate thickness that best fits the spatial distribution of subsidence and uplift rates is 40 km consistent with previous estimates based on total vertical deflection because volcanic loading dominates the vertical motion signal hawaiian islands appear to follow a predictable trajectory of vertical motion when they reside within one flexural half wavelength of the active volcanic center islands initially subside at rapid and decreasing rates in the first 1 myr following their construction uplift relatively slowly 1 2 5 myr following their construction and eventually subside again but at slow rates within 5 myr of their construction this observed pattern of uplift and subsidence is consistent with the pattern of vertical motion predicted to result from volcanic loading at the hawaiian hotspot lithospheric migration over the long wavelength topographic swell associated with the hawaiian hotspot has a comparatively minor influence on island uplift and subsidence its contribution to island vertical motion is not readily observed in our data with the possible exception of some uplift observed in the past 500 kyr on o ahu that might correspond to non steady state behavior of the hawaiian plume

the internal magma reservoir of large intrusions revealed by multiphase rayleigh fractionation the fractionation progress of a crystallizing basaltic magma is recorded in the changing mineral compositions of binary solutions that form a part of plagioclase olivine and augite when such compositional data are plotted against an independent measure of progress such as volume they can often be described by a rayleigh equation that reveals details of the crystallization history a binary solution crystallizing by itself follows a path determined by the rayleigh exponent d 1 where d is the partition coefficient x1 x1 l x is mole fraction 1 is low melting component l is liquid s is solid in company with another phase however such a binary solution may follow a wide range of paths in an envelope about d 1 ranging from a f d 1 to b d 1 f where f is the fraction of the active phasecthe binary solution under consideration the upper limiting curve an extended fractionation path is given by a above whereas a full x2 depletion path b defines the lower limit this range of alternatives is here codified and supplemented by considerations of residual porosity the result is a rayleigh equation in five variables that can illuminate magmatic history including the probability of the existence of an internal reservoir that damps the depletion effect the range of paths can help to identify evidence for and causes of leading edge fractionation of ascending magma small packet crystallization pressure variations off cotectic excursions and oscillating modal variation

plagioclase an range and residual porosity in igneous cumulates of the kiglapait intrusion the range in an content of plagioclase in grain mounts of igneous cumulates provides a measure of diversity that is uniquely preserved in plagioclase because of its well known refractory nature to a first approximation such data provide when calibrated an estimate of the residual porosity or fraction of trapped liquid in each specimen the ensemble of specimens then provides a model for the stratigraphic variation of residual porosity the raw data however include pre cumulus zoning that can be isolated from in situ zoning by textural analysis in thin section the baseline of residual porosity determinations was earlier determined for the lower zone of the kiglapait intrusion from the content of excluded components in the solid rock compared with their content in the melt as calculated by summation and rayleigh fractionation the baseline equation was then used to calibrate the residual porosity obtained from the an range in grain mounts this calibration is now extended to the remainder of the intrusion the an range and the calculated residual porosity decrease to zero at 99 solidified pcs and then rise to the end of crystallization the data suggest initial porosities smaller than 0 35 allowing for pre cumulus zoning the data suggest a dominance of adcumulates in the intrusion and these impermeable barriers occupy 75 of the rocks in the lower zone they occur at intervals of 1 to rarely 15 m and thereby restrict the likelihood of compaction over thick mushy zones variations in the fo range of olivine are also observed in grain mounts and they follow those in plagioclase however they are in part due to subsolidus equilibration with fe ti oxides and augite the new calibration is successfully applied to the skaergaard intrusion to supplement the published results from excluded components with some interesting contradictions

electron spin resonance esr dating abstract esr dating has been systematically applied in earth sciences and archaeology since 1975 when ikeya dated a stalactite from the akiyoshi cave in japan in the meantime this new technique has been successfully applied to the dating of materials such as speleothems spring deposited travertines mollusc shells corals and tooth enamel the present research focuses on the dating of quartz which allows the age assessment of heated ceramics volcanic rocks intrafault material or windblown sediments esr dating is based on the measurement of the number of paramagnetic centers in a mineral these centers are generated by alpha beta and gamma radiation of the matural radioelements such as u th and k and have accumulated over time two parameters have to be determined the accumulated dose ad and the dose rate d to which the sample was exposed this review comprises three major parts a introduction into esr dating b application of the method and c appendices giving detailed description of dose rate calculation physical basis of electron spin resonance the esr spectrometer and esr lines the major emphasis lies on the outline of the application of esr dating this includes the discussion of the esr signals of the various materials sampling sample preparation and measurement techniques

quaternary geochronology using the uthpb method abstract we describe a method of uranium thorium lead u th pb isotopic age dating for quaternary rocks the approach uses an instrumental mass discrimination correction for lead isotope ratios which allows small enrichments of radiogenic 206ph and 208ph to be detected at the level of 0 001 igneous rocks hosting minerals with a range in 238 u 204 pb values of 100 can be dated with uncertainties of approximately 15 20 kyr a quaternary rhyolite dated at 1 19 ma by k ar yields a 238u 206ph age of 1 03 0 10 ma a holocene dacite 9 5 ka has uniform 206 pb 207 pb to within 0 0015 in groundmass phases but 1 mm plagioclase phenocrysts have lower 206 pb 207 pb by 0 105 0 002 indicating contamination of the magma after plagioclase crystallization high precision 206 pb 207 ph ratios may be a useful new tool for petrogenetic studies

esr and ams based 14c dating of mousterian levels at mujina pecina dalmatia croatia abstract this paper presents the first chronometric dates for sediments that contain a mousterian industry in dalmatia south croatia electron spin resonance esr dating was conducted on two teeth from the mousterian level e1 at the site of mujina pecina additionally five bone and one charcoal sample from five different strata of origin at this site were dated by accelerator mass spectrometry ams assuming 30 moisture for both the gamma and beta dose rate calculations the mean lu esr age estimate is 44 5 ka for level e1 which is statistically indistinguishable from the mean eu esr age estimate of 40 7 ka a single uncalibrated 14 c age from the e1 e2 interface yielded an age estimate of 45 170 2780 2060 years bp while the mean of the five samples from overlying mousterian levels is 39 3 ka the true calibrated age of this mean is about 42 ka which means that the entire stratigraphic profile in mujina pecina apparently was very rapidly deposited and that the esr age regardless of uptake model is in good agreement with the calibrated 14 c mean age temporally mujina pecina overlaps with pontinian mousterian sites in west central italy and vindija level g3 from northwestern croatia however there are notable differences between the mousterian industry from mujina pecina and these other sites collectively the croatian sites yield important evidence on the adaptation of european mousterian people

overestimate of stalagmitic calcite esr dates due to laboratory heating in the use of esr for dating stalagmitic calcite from palaeolith1c caves it has recently been reported that to obtain reliable ages the samples should be heated before measurement for example for 24 h at 170 190 c specifically this procedure has been used by yokoyama et al 1 for samples from the lowest stalagmitic floor in caune de l arago the site of the tautavel man in southern france and an age of 700 kyr obtained however the results presented here indicate that straight line extrapolation involved in finding the age is not valid if this heating procedure is used and that its use leads to a substantial overestimate of the age by nearly a factor of two in the application mentioned

esr dating of the rotoiti breccia in the taupo volcanic zone new zealand abstract electron spin resonance esr can be used to determine the time of formation of quartz in volcanic rocks based on the trapping of changes in the quartz resulting from environmental radiation the method has been used on quartz from a rhyolitic pyroclastic flow the rotoiti breccia deposited ne of rotorua new zealand it yields a date of 45 2 8 2 ka bp the mean of ages of 48 6 and 41 8 ka bp obtained from the al and ti centers respectively this result is in good agreement with previous 14c ages of 41 6 ka bp and 44 2 4 3 ka bp but does not agree with a date of 71 6 ka bp based on uranium disequilibrium we suggest that this discrepancy reflects the time difference between attainment of equilibrium at depth and the emergence time of the pyroclastic flow on the surface where radiation bombardment commenced

electron spin resonance dating of the fossil deposits in the naracoorte caves south australia the caves near naracoorte south australia contain one of the richest and most diverse fossil faunal assemblages on the australian continent three sites were selected for electron spin resonance esr dating because clastic fossiliferous sediments were sandwiched between speleothem layers this allows independent age control by highly precise thermal ionization mass spectrometry tims u series dating we find that all esr results agree within the constraints given by the u series dates and allow further refinement of the age of the fauna analysed indicating that most of the fauna in the large victoria cave fossil chamber is twice as old as reported previously our dating results spanning from 280 to 500 ka for the fossil chamber victoria cave to about 125 ka for the grant hall victoria cave and 170 to 280 ka for the fossil chamber cathedral cave indicate little change if any in the megafaunal assemblage from the early middle to the early late pleistocene this changed dramatically after the last interglacial when a large proportion of the megafauna suddenly disappeared copyright 2001 john wiley sons ltd

the impact of hydrological changes on travertine deposits related to thermal springs in the pamukkale area sw turkey pamukkale thermal waters 35 c exhibiting calcium bicarbonate sulfate composition and high carbon dioxide concentration are of a predominantly meteoric origin the meteoric fluid circulating through faults and fractures is heated by magmatic intrusions at great depth and ascends from deep reservoirs to the surface mixing with relatively cold groundwater in the near surface zone promotes different saturation conditions with respect to calcium carbonate that later precipitates at depth and or the surface dissolution deposition processes of calcium carbonate both at surface and depth environments may help to reconstruct past climate direction in the field during wet climate conditions a high rate of calcium carbonate accumulation would be expected to occur at the surface because thermal fluid would be under saturated with respect to calcium carbonate at depth because of a relatively higher mixing ratio with cold groundwater during dry climate conditions the thermal fluid would be super saturated at depth because of the highly acidic environment hydrometeorological studies reveal that the annual precipitation at the pamukkale hydrothermal field tends to decrease with time this climatic change in the area was also detected from geological records while humid climate conditions prevailed during the late quaternary the area has recently been affected by arid semi arid climate conditions followed by some episodic transitions this study has shown how the system has possibly reacted to different climate conditions since antiquity

progress in esr dating of pleistocene corals a new approach for de determination abstract esr dating has been widely applied for dating of corals of the age up to 500 000 to 600 000 years ago many studies have yielded promising results but the accurate determination of the equivalent dose d e remains a major limitation inflexion points in the dose response curve are shown to hinder correct fitting and limit the reliability of d e values here we present a new approach to obtain more reliable d e values

cenozoic paleo environmental evolution of the pamir tien shan convergence zone abstract the retreat of the tethys sea and the uplift of the tibetan plateau play the critical roles in driving asian climatic changes during the cenozoic in the pamir tien shan convergence zone over 3000 m of cenozoic successions consisting of marine deposits in the lower continental clay and fine sand in the middle and molasse in the upper part record the evolution of the tethys sea the asian aridification and the deformation of the pamir in this work the existing biostratigraphic subdivisions and new electronic spinning resonance dating results were used to assign ages to formations within the ulugqat section sedimentary facies analysis and multi proxy indices were used to reconstruct the paleo environmental evolution the results show 1 the pamir tien shan convergence zone has undergone progressive environmental changes from shallow marine before 34 ma to arid land at 23 ma and finally to inter mountain basin by 5 3 ma 2 the overall increase in mean size of grains decrease in redness in magnetic susceptibility and in proportion of the ultrafine component of the sediments studied revealed a long term strengthening in potential energy to transporting medium cooling and enhanced continental aridity respectively 3 the easternmost edge of the tethys sea prevailed in the western tarim basin from late cretaceous to early cenozoic and finally retreated from this region around the eocene oligocene transition which in turn strengthened the asian aridification 4 accumulation of molasse with an upper age of 1 ma suggests that the deformation front of the pamir migrated to this area at or before that time

the use of glass for dating volcanic ash by thermoluminescence the development of a new physical dating method for late pleistocene tephrochronometry is described here tests of laboratory procedures applied to glass from independently dated samples show that the thermoluminescence tl additive dose dating method can yield accurate ages for both proximal and distal tephra from a few hundred years to at least 400 ka the technique involves purification of 4 to 11 m glass by heavy liquid centrifugation pre tl readout heating at 50 75 c for 8 days and careful regression analysis of tl growth curves several unknown age tephra are dated directly by this method for the first time these include five ash beds from summer lake oregon 67 200 ka a sheep creek valley ash from alaska 81 9 ka an ash from nevada 200 50 ka correlated to the wadsworth tephra an unknown ash 210 30 ka from rye patch dam in nevada previously correlated to the 400 to 600 ka dibekulewe tephra and ash 9m from washtucna in eastern washington 250 30 ka

esr dating of tooth enamel a comparison with kar dating abstract the reliability of the esr dating of tooth enamel was tested for a famous italian palaeolithic site isernia la pineta already dated by the k ar method esr ages calculated with early uranium uptake model eu linear uranium uptake model lu and us esr model are between 80 and 251 ka the us model with the hypothesis of inverse correlation between esr signal heights and uranium concentration resulted in an age of about 450 ka for one sample these ages are compared with a k ar age of 736 ka

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

u series analyses of the lower travertine at ehringsdorf ddr abstract u series analyses have been made of travertine samples from the archaeological site at ehringsdorf weimar the lower travertine in which hominid remains were found yields apparent ages from 350 000 to 200 000 yr correlation between isotope ratios yields an age of about 230 000 yr one sample of the upper travertine gives and age of 111 000 47 000 yr both upper and lower travertines contain fauna and flora indicative of interglacial conditions the lower travertine was deposited during isotope stage 7 while the upper travertine may have been formed during isotope stage 5 this contradicts most earlier biostratigraphic studies which assigned both lower and upper travertines to stages of the eem interglaciation correlative with isotope stage 5 the fauna and flora of the lower travertine are significantly different from those of the upper travertine however and in some respects are transitional to those of the travertines of bilzingsleben which appear to be older yet

dynamics of evolving magma chambers textural and chemical evolution of cumulates at the arrival of new liquidus phases abstract basaltic magma chambers are best exemplified by layered intrusions fossilized natural laboratories that historically constrain most fundamental principles of igneous petrology progressive fractional crystallization of basaltic melts in layered intrusions results in successive appearance of 5 10 liquidus minerals most minerals appear in the stratigraphy of layered intrusions via two distinct stages they first emerge as oikocrysts large irregularly shaped and interstitial crystals that form in a crystal liquid framework and then as primocrysts relatively small idiomorphic and cumulus crystals that crystallize from a main magma body the transition from oikocrysts to primocrysts is commonly marked by the following textural and chemical features a a similarity in chemical composition of the last forming oikocrysts and the first forming primocrysts b slow arrival modal overabundance and finer than normal size of the first primocrysts c a low abundance of trapped liquid in rocks with the first forming primocrysts d a step like increase in mineral dihedral angle in rocks slightly below the level of the primocryst arrival and e the rims on plagioclase primocrysts that are identical in composition to cores of plagioclase primocrysts at the first appearance of new liquidus phases higher up in the section the phase equilibria control on the cumulus stratigraphy of layered intrusions require large long lived and largely molten magma chambers and therefore their origin is not compatible with several recent concepts that deny the existence of such reservoirs in the earth s crust we therefore suggest that the systematic changes associated with the arrival of cumulus phases in layered intrusions are best explained by a traditional concept that considers layered intrusions as large initially crystal free melt bodies that gradually lose heat and crystallize from margins inwards through thin solidification fronts the entire magma body during its internal evolution is thought to be kinetically supercooled i e kept slightly below its liquidus temperature with respect to cumulus phases that crystallize at the margins each new cumulus phase arrives on the liquidus with some kinetic delay and nucleates heterogeneously against pre existing crystals at the floor roof and sidewalls of basaltic magma chambers this implies that internal differentiation of basaltic magma chambers mostly occurs through convective separation of evolved liquid from in situ growing crystals and its mixing with the main magma body

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

geochronology of drowned hawaiian coral reefs abstract two deeply submerged coral reefs were sampled with the hurl submersible pisces v off the islands of hawaii and maui an ancient fringing reef at 950 m depth on the kohala slope of hawaii was observed from deep towed camera photographs and during submersible operations a second reef at 1650 m depth on the haleakala slope of maui was observed on side scan images deep towed camera photographs and during submersible observations ages of the two reefs were determined by electron spin resonance dating with a signal intensity for aragonitic coral at g 2 0007 used to ascertain the accumulated dose by the additive dose method uranium concentration was measured by neutron activation analysis the chronology of the reefs indicates that drowning coincided with periods of rapid global climate change at the termination of continental glaciation at approximately 250 ka and 340 ka the drowning events correlate with oxygen isotope stage boundaries 7 8 and 9 10 these data support models of reef drowning on subsiding volcanic edifices

sequential thrusting model for mountain building constraints from geology and heat flow of taiwan in this study we analyze the thermal evolution of the taiwan fold and thrust belt based on the available geological information a finite element program is used to simulate the complex kinematics of the observed sequential thrusting and the interplay of uplift erosion and sedimentation processes the discrete sequential thrusting model successfully reproduces the observed decrease in heat flow at the deformation front in northern taiwan this reveals that the heat flow drop may be due to the recent stacking of cold thrust sheets at the deformation front this inference is consistent with the high seismicity and dense quaternary fault distribution in western taiwan the model also successfully reproduces the observed high heat flow in the central ranges suggesting that the observed high heat flow may be a result of tectonic unroofing due to active underplating uplift and erosion these conclusions are insensitive to uncertainties in the frictional coefficient on the thrust plane

kiglapait mineralogy v feldspars in a hot dry magma the lithology of the 1 305 ga kiglapait intrusion is dominated by a lower zone of troctolite succeeded by an upper zone of olivine gabbro ferrodiorite and syenite with olivine composition of pure fayalite the feldspar composition of the intrusion varies from an 68 to an 9 over a thickness of 8 4 km from the base to a sandwich horizon under an upper border zone the anhydrous nature of the kiglapait syenites is shown by their high temperature by the loss of minor biotite up stratigraphy in the intrusion and the absence of amphibole the end stage feldspar of the kiglapait syenites is that of a solidus embedded in a solvus in a 3 kbar eutectic at 1000 c the end member assemblage at temperature and pressure is invariant the final bulk composition is relatively an rich an 11 with a composition of x or 1 3 when projected to the ab or sideline the experimental feldspar solvus when corrected for the effects of an and ba and referred to 3 kbar penetrates the solidus and fits the experimental tie lines these conditions precede a stage of local coarsening under subsolidus conditions that is found in colloform symplectites invading mesoperthite the oligoclase orthoclase symplectites are iso compositional with their host mesoperthites the coarsening is assumed to be related to a plausibly f rich vapor phase that is locally consumed with time the observed phase compositions indicate the end of exsolution at 800 c at 3 kbar on the binodal solvus

speleothems travertines and paleoclimates abstract age data for about 660 speleothems and about 140 spring deposited travertines were collected including many unpublished results these data were plotted as histograms and also as error weighted frequency curves on a 350 000 yr scale these plots clearly show periods of increased speleothem travertine growth as well as times of cessation the periods of most frequent speleothem growth were between approximately 130 000 and 90 000 yr ago and since about 15 000 yr ago such periods before 150 000 yr ago however cannot be yet recognized because of a lack of sufficient data and the associated uncertainties of dates in this age range a comparison with the oxygen isotope record of deep sea core v28 238 shows a clear relationship indicating that terrestrial calcite formation is controlled by paleoclimatic fluctuations the evident climatic stimulation of quaternary calcite formation is readily explained geochemically and is substantiated by the obvious difference in speleothem travertine growth as a function of geographic position

dating and characterization of polymorphic transformation of aragonite to calcite in pleistocene bivalves from rhodes greece by combined shell microstructure stable isotope and electron spin resonance study absolute dating of diagenesis is a challenging yet significant problem reconstructing the depositional and diagenetic history of a late pleistocene coralligene type red algal reef and overlying maerl red algal sand from the plimiri coastal cliff se island of rhodes greece is enabled using a combination of microstructure stable isotope analyses and electron spin resonance of large bivalve shells partially altered by diagenesis these shells consisting of both original shell aragonite and polymorphic transformed rims now consisting of neomorphic spar provide the opportunity to date the primary age when the shells were precipitated as well as the age of their polymorphic transformation the contamination of samples presented a significant problem for interpreting ages based on data from electron spin resonance esr alone however sample contamination was evaluated with quantitative xrd providing the opportunity to apply corrections which increased reliability of the ages the carbon and oxygen stable isotope values and the neomorphic spar microtexture suggested that the polymorphic transformation at plimiri took place in a meteoric environment with a high and increasing fluid rock ratio the electron spin resonance dates combined with the vertical sedimentary evolution allowed to assign the formation of the red algal reef to the marine isotope stages 6 to 5e transgressive event ca 135 to 120 ka and to identify meteoric diagenetic phases during possibly the marine isotope stage 5d and the upper marine isotope stage 5c to lower 3 the use of electron spin resonance dating of neomorphic spar and age correction for sample contamination is presented herein for the first time and the results suggest that it might provide a useful tool to date late pleistocene diagenesis

esr dating of ancient flints natural radioactivity can produce measurable amounts of radiation damage in rocks and glasses and the gradual accumulation of this damage with time provides a built in clock that can be used as a dating tool for geology and archaeology although a studied technique for estimating this damage involves measurements of stored thermoluminescent tl activity1 4 several authors have reported the direct observation of natural radiation damage by esr5 7 we describe here esr measurements on a damage signal which we have found to be present without exception in a wide variety of natural flints the point defect responsible for the signal is identified and the samples are calibrated with an artificial damage simulation preliminary age determinations are presented for several natural flints flint artefacts heated in antiquity will have their clock reset to zero and measurements on one sample suggest that the esr technique may have applications in the study of early cultures

refining the chronology of acheulean deposits at porto maior in the river mino basin galicia spain using a comparative luminescence and esr dating approach abstract trapped charge dating of optically bleached quartz which involves techniques such as electron spin resonance esr and thermally transferred optically stimulated luminescence tt osl is increasingly being used to establish middle and early pleistocene chronologies for archaeological palaeontological and palaeoenvironmental sedimentary sequences comparative dating studies that make use of several independent or semi independent radiometric techniques in tandem are an invaluable means of assessing the reliability of optically bleached quartz dating methods and ascertaining empirical relationships between different quartz dating signals in this study we undertake a comparative dating evaluation of single grain tt osl and various esr signals that exhibit different optical resetting properties al ti li and where measurable ti h centres at the middle pleistocene archaeological site of porto maior northwest spain which contains a distinctive regionally significant acheulean stone tool assemblage we expand the existing chronological framework for porto maior using single grain tt osl dating derive combined numerical ages for individual depositional units using bayesian modelling and further examine the relationship between esr and tt osl signals by reviewing a range of published comparative dating studies the new single grain tt osl ages obtained for unit pm3 at porto maior 225 31 ka and 242 32 ka are in close agreement with previously published esr ti li ages for this unit 266 23 ka and 279 26 ka and significantly younger than those reported for the al centre 441 75 ka and 452 66 ka our broader comparison of published tt osl esr dating results also shows statistically significant agreement between single grain tt osl and ti li centre ages in other sedimentary settings suggesting a potentially closer relationship between the tt osl producing traps and the ti li paramagnetic centres in quartz rather than between the tt osl and al centre signals the bayesian modelling results for porto maior enable us to refine the existing bracketing depositional age for the archaeological accumulation at porto maior and provide a stronger statistical foundation for chronostratigraphic correlations with other acheulean archaeological deposits found in the mino river basin the bayesian model indicates that the entire porto maior sedimentary sequence was deposited between 312 6 32 6 ka and 18 8 7 7 ka and that the in situ large cutting tool assemblage from level pm4 most likely accumulated during marine isotope stage 7 mean depositional age 210 7 24 7 ka the results of this study reinforce the usefulness of applying the multiple centre mc esr dating approach in many dating contexts and demonstrate the value of undertaking comparisons between semi independent quartz dating signals in order to maximise the reliability of esr and single grain tt osl quartz chronologies

reliability of thermoluminescence dating of stalagmitic calcite the dating of stalagmitic calcite at the early hominid site of caune de l arago france by the esr technique of yokoyama et al 1 has yielded ages for the underlying floor of 7 105 yr these are in serious disagreement with the chronology obtained by thermoluminescence tl 2 which indicates a date of around 3 105 yr the discrepancy has been attributed3 to instability of the tl 280 c dating signal for which a mean life of 2 105 yr was proposed here the arguments on which this claim is based are criticized and evidence is presented that corrections to tl age measurements incurred by signal fading are even for the oldest stalagmites from the site probably 15 the conflict between the tl and esr chronologies at caune de l arago is explicable in terms of the esr results reported by skinner4

esr dating of corals abstract the ages of 24 coral samples from barbados and the new hebrides were determined simultaneously by esr and another independent dating method and ms u series and 14 c all parameters for esr dating were determined without cross calibration with another dating method including thermal stability and effective efficiency the results show a relatively good concordance furthermore a systematic esr dating study on the reef tracts of barbados 83 samples revealed satisfactory agreement between esr and u series data whereas previously published he u data seemed to show open system behaviour the thermal stability of the esr signal at g 2 0007 0 0002 estimated to be in the range of 500 ka does not seem to have an apparent influence on the esr results

the timing and cause of megafauna mass deaths at lancefield swamp south eastern australia abstract lancefield swamp south eastern australia was one of the earliest sites to provoke interest in pleistocene faunal extinctions in sahul pleistocene australia new guinea the systematic investigation of the deposit in the early 1970s identified megafaunal remains dominated by the 100 200 kg kangaroo macropus giganteus titan associated radiocarbon ages indicated that the species was extant until c 30 000 bp suggesting significant overlap with human settlement of sahul this evidence was inconsistent with contemporary models of rapid human driven extinctions instead researchers inferred ecological tethering of fauna at lancefield swamp due to intense drought precipitated localised mass deaths consistent with late pleistocene climatic variability later investigations in another part of the swamp the mayne site remote to the initial investigations concluded that mass flow disturbed this area and electron spin resonance esr analyses on megafauna teeth returned wide ranging ages to clarify site formation processes and dating of lancefield swamp we excavated new test pits next to previous trenches in the classic and mayne sites we compared absolute chronologies for sediments and teeth sedimentology palaeo topography taphonomy and macropod age at death across the swamp luminescence dating of sediments and esr analysis of teeth returned ages between c 80 000 and 45 000 years ago we found no archaeological remains in the bone beds and evidence of carnivore activity and fluvial action in the form of reactivated spring flow the latter disturbed limited parts of the site and substantial areas of the bone beds remained intact the faunal assemblage is dominated by megafaunal adult macropus consistent with mass die offs due to severe drought such droughts appear to have recurred over millennia during the climatic variability of marine isotope stages 4 and 3 these events began tens of millennia before the first appearance of aboriginal people in sahul and only the very youngest fossil deposits could be coeval with the earliest human arrivals therefore anthropogenic causes cannot be implicated in most if not all of mass deaths at the site climatic and environmental changes were the main factors in site formation and megafauna deaths at lancefield swamp