aridity driven decoupling of δ13c between pedogenic carbonate and soil organic matter pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology the c of pedogenic carbonate c c has been widely used to document the rise and expansion of c plants over the cenozoic this application requires a fundamental presumption that in soil pores soil respired co dominates over atmospheric co during the formation of pedogenic carbonates however the decoupling between c c and c of soil organic matter c som have been observed particularly in arid regions suggesting that this presumption is not always valid to evaluate the influence of atmospheric co on soil c c here we performed systematic c analyses of paleosols across the chinese loess plateau with the sample ages spanning three intervals the holocene the late pleistocene and the mid pliocene warm period our paired c c and c som data reveal broadly divergent trending patterns using a two component co mixing model we show substantial incorporations of atmospheric co up to 60 into soil pore space during carbonate precipitation this result readily explains the enrichment of c c and its divergence from c som as a consequence c of pedogenic carbonates formed under semiarid and or arid conditions are largely driven by regional aridity through its control on soil co composition and thus cannot be used to evaluate the relative abundance of c versus c plants nonetheless these carbonates can be applied for atmospheric co reconstructions even for periods with low co levels

integrated interpretation of 3d seismic data to enhance the detection of the gold bearing reef mponeng gold mine witwatersrand basin south africa we present an integrated approach to the seismic interpretation of one of the world s deepest gold ore body carbon leader reef using three dimensional seismic data ultrasonic velocity measurements at elevated stresses and modified instantaneous attribute analysis seismic wave velocities of the drill core samples quartzite shale and conglomeratic reef from the mine are sensitive to uniaxial stress changes i e they slowly increase with increasing pressure until they reach maximum value at 25 mpa for all the samples seismic velocities are constant above 25 mpa indicating a possible closure of microcracks at stress corresponding to 1 0 km 1 5 km a reflection coefficient of 0 02 computed between hanging wall and footwall quartzites of the carbon leader reef ore body suggests that it may be difficult to obtain a strong seismic reflection at their interface our modified seismic attribute algorithm on the other hand shows that the detection of the lateral continuity of the carbon leader reef reflector can significantly be improved by sharpening the seismic traces three dimensional seismic data reveal that faults with throws greater than 25 m that offset the carbon leader reef can clearly be seen faults with throws less than 25 m but greater than 2 m throw were identified through horizon based attribute analysis while most dykes and sills with thickness less than 25 m were invisible the detection of the lateral continuity of the carbon leader reef reflector and its depth position is greatly improved by integrating the modified instantaneous attributes with controls from borehole observations the three dimensional visualization and effective interpretation of the carbon leader reef horizon shows a host of structurally complex ore body blocks that may impact future shaft positioning and reduce its associated risks

the proportionality between relative plate velocity and seismicity in subduction zones the magnitude and rate of seismicity differ between subduction zones calculations of background seismicity rates based on a global model of subduction zone seismicity reveal a positive correlation between relative plate velocity and background seismicity yet only the seismically quieter zones seem capable of generating magnitude 9 earthquakes

spatiotemporal distribution of interplate coupling in southwest japan from inversion of geodetic data 1 we determine the spatiotemporal distribution of slip or slip deficit on the subduction interface of the nankai trough over an entire earthquake cycle using geodetic data including leveling triangulation and trilateration sea level and gps surveys obtained during the past 100 years in southwest japan we develop a new inversion method that accounts for long term crustal deformation coseismic earthquake displacements and stress relaxation of the viscoelastic asthenosphere from this analysis we obtain a model that shows postseismic afterslip on the deeper part of the plate interface following the 1946 nankaido earthquake significant afterslip is found beneath central shikoku that totals about 0 8 m the slip deficit rate during the interseismic period is 5 6 cm year in the n50 w n60 w direction which is consistent with the relative plate motion between the philippine and amurian plates a fully locked region is found in the shallower portion 30 km and the slip deficit rate has a maximum at a depth of about 20 km the plate interface deeper than 30 km is slowly slipping the amount of slip deficit reaches about 3 3 m off shikoku and about 2 m off the kii peninsula 50 years after the 1946 earthquake this suggests that fault healing and full interplate coupling has occurred by this time along the nankai trough

physical property analysis and preserved relative amplitude processed seismic imaging of volcanogenic massive sulfides a case study from neves corvo portugal neves corvo is one of the biggest mining districts on the portuguese side of the iberian pyrite belt hosting six different lower carboniferous copper zinc lead and tin orebodies including lombador neves grac a corvo zambujal and semblana during the past 50 years geological geochemical and geophysical methods were utilized in the exploration of volcanogenic massive sulfide deposits at neves corvo electromagnetic earth resistivity and principally gravimetry methods played major roles in the geophysical exploration of the area however in 2011 as the exploration depth for volcanogenic massive sulfide mineralization became ever deeper the surface reflection seismic technique was trialled initially elastic property measurements were employed on numerous core samples to determine the seismic properties of the major formations of neves corvo the contrast in acoustic impedance values derived from these measurements showed that there should be a significant difference in the seismic response of mineralization relative to the surrounding host rocks based on this a high resolution 3d seismic survey was acquired over the neves corvo mine and its southeastern extension in order to image known deep volcanogenic massive sulfide mineralization to validate the seismic reflection technique and to potentially identify new mineralization targets as a result the semblana and lombador deposits were successfully imaged along with key lithological contacts and geologic structures additionally copper sulfide extensions south of semblana were discovered unfortunately all of the high priority targets that were identified from the seismic data were subsequently drilled and many of them found to be non economic in order to overcome the non uniqueness of the original seismic data full waveform sonic and pseudo logs were used to model different interfaces and calibrate the seismic data these results indicated that preserved relative amplitude processing might be of importance to help reduce the ambiguity in direct detection of volcanogenic massive sulfide based on seismic amplitude anomalies the customized relative amplitude processing of a sub dataset over the semblana deposit was then performed the newly obtained seismic cube was calibrated with existing drillholes and a volumetric interpretation was performed by utilizing amplitude based geobodies eventually superior target zonation and precision for the subsequent deep drilling campaign was achieved with the revised interpretation clearly showing that the high priority targets originally identified from the legacy data would not have passed the targeting criteria in the reprocessed data due to their relatively weak amplitude response the results obtained from this study inspired the subsequent reprocessing of the full seismic dataset

the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

stepwise expansions of c4 biomass and enhanced seasonal precipitation and regional aridity during the quaternary on the southern chinese loess plateau abstract the expansion of c 4 plants is one of the most prominent vegetation changes in the global ecosystem during the cenozoic era although c 4 plant expansions in the latest miocene have been widely reported factors driving the expansions are still in debate and the details of vegetation changes during the quaternary have not been well studied here we present high resolution carbon isotope time series of both organic matter and bulk carbonates covering the past 2 58 ma derived from the loess soil successions on the southern chinese loess plateau the organic matter 13 c values indicate stepwise c 4 plant expansions initiated at 1 6 and at 0 43 ma respectively we conclude that such tectonic time scale c 4 plant expansions are controlled by enhanced seasonality of precipitation relatively more precipitation in the warm growing season as well as regional aridity and this long term fluctuation superimposes on the orbital scale variations of c 4 plants while the latter appears phase locked with cyclical changes of summer monsoon circulations

landstreamer seismics and physical property measurements in the siilinjarvi open pit apatite phosphate mine central finland abstractwe tested the applicability of a newly developed broadband 0 800 hz digital based seismic landstreamer for open pit mine planning in the apatite bearing siilinjarvi mine in central finland four seismic profiles in total approximately 2 5 km long 2 4 m source and landstreamer receiver spacing two inside the pit and two on its margins were acquired in combination with wireless recorders connected to 10 hz geophones and fixed at every 10 m spacing along the seismic profiles while the streamer data were being acquired downhole logging and laboratory physical property measurements on core and rock samples were carried out to not only support the seismic interpretations but also to provide information about the possible geophysical signature of these unique types of deposits in spite of a highly noisy mining environment seismic data of high quality were acquired however reflection processing and interpretations were challenged by the geologic complexities of several generations of basic and

subsurface mapping in the iberian pyrite belt using seismic reflection profiling and potential field data the iberian pyrite belt ipb hosts world class massive sulphide deposits such as neves corvo in portugal and rio tinto in spain in portugal the palaeozoic volcanic sedimentary complex vsc hosts these ore deposits extending from the gr ndola alcacer region to the spanish border with a nw se to wnw ese trend in the study area between the neves corvo mine region and alcoutim close to the spanish border the vsc outcrops only in a small horst near alcoutim sparse exploration drill hole data indicate that the depth to the top of the vsc varies from several 100 m to about 1 km beneath the mertola formation flysch cover mapping of the vsc to the se of neves corvo mine is an important exploration goal and motivated the acquisition of six 2d seismic reflection profiles with a total length of approximately 82 km in order to map the hidden extension of the vsc the data providing information deeper than 10 km at some locations were integrated in a 3d software environment along with potential field geological and drill hole data to form a 3d structural framework model seismic data show strong reflections that represent several long variscan thrust planes that smoothly dip to the nne outcropping and previously unknown late variscan near vertical faults were also mapped our data strongly suggest that the structural framework of neves corvo extends south eastwards to alcoutim furthermore the vsc top is located at depths that show the existence within the ipb of new areas with good potential to develop exploration projects envisaging the discovery of massive sulphide deposits of the neves corvo type

pedogenic carbonate proxies for amount and seasonality of precipitation in paleosols the depth to carbonate nodular bk horizon in soils d in cm is correlated with mean annual precipitation p in mm so that bk horizons are deep in subhumid regions but shallow in semiarid regions previous quantifications of this relationship are unchanged by this new compilation of 807 soils p 137 24 6 45 d 0 013 d 2 where r 2 0 52 and standard error s e 147 mm in most north american postglacial soils the bk horizon is thin and well defined whereas in monsoonal tropical soils of pakistan and kenya the bk horizon is thick and diffuse data from 675 modern soils define the relationship between the thickness of soil with nodules t in cm and mean annual range of precipitation m in mm difference between monthly means of wettest and driest months m 0 79 t 13 71 where r 2 0 58 and s e 22 mm the relationship between carbonate nodule size s in cm and soil age a in ka is quantified by 9 radiocarbon dated soils from las cruces new mexico a 3 92 s 0 34 where r 2 0 57 and s e 1 8 k y these transfer functions are applied to reconstructing paleoclimatic change from paleocene eocene paleosols of the north horn formation and flagstaff limestone of axhandle canyon utah the terminal paleocene spike of warmth recorded by fossil plants in nearby wyoming was coincident with a brief peak in both mean annual precipitation and mean annual range of precipitation in utah

geodetic imaging of plate motions slip rates and partitioning of deformation in japan 1 interseismic deformation in japan results from the combined effects of tectonic processes including rotation of crustal blocks and the earthquake cycle process of elastic strain accumulation about upper plate faults and subduction zone interfaces we use spherical linear block theory constrained by geodetic observations from densely spaced global positioning system gps stations to estimate plate motions fault slip rates and spatially variable interplate coupling on the japan kuril sagami and nankai subduction zones the reference model developed in this paper consists of 20 blocks produces a mean residual velocity magnitude of 1 84 mm yr at 950 stations and accounts for 96 of the observed interseismic deformation signal we estimate fault slip rates in excess of 15 mm yr along the niigata kobe tectonic zone and itoigawa shizuoka tectonic line through central japan confirming their hypothesized roles as major tectonic boundaries oblique convergence across the nankai trough is partitioned with 3 4 of the 30 mm yr of trench parallel motion accommodated by strike slip motion on the subduction interface and the remaining 1 4 accommodated by right lateral slip on the median tectonic line in contrast our models suggest negligible slip partitioning in eastern hokkaido where oblique slip on the japan kuril subduction interface accommodates all of the trench parallel component of relative plate motion inferred spatial variations in the rake and magnitude of slip deficit on subduction zone interfaces reflect the influences of megathrust geometry and earthquake cycle processes such as enhanced elastic strain accumulation about seismic asperities and coseismic sense fault motion indicative of silent slip events or afterslip following large earthquakes

geology and tectonics of japanese islands a review the key to understanding the geology of asia abstract the age of the major geological units in japan ranges from cambrian to quaternary precambrian basement is however expected as the provenance of by detrital clasts of conglomerate detrital zircons of metamorphic and sedimentary rocks and as metamorphic rocks intruded by 500 ma granites although rocks of paleozoic age are not widely distributed rocks and formations of late mesozoic to cenozoic can be found easily throughout japan rocks of jurassic age occur mainly in the jurassic accretionary complexes which comprise the backbone of the japanese archipelago the western part of japan is composed mainly of cretaceous to paleogene felsic volcanic and plutonic rocks and accretionary complexes the eastern part of the country is covered extensively by neogene sedimentary and volcanic rocks during the quaternary volcanoes erupted in various parts of japan and alluvial plains were formed along the coastlines of the japanese islands these geological units are divided by age and origin i e paleozoic continental margin paleozoic island arc paleozoic accretionary complexes mesozoic to paleogene accretionary complexes and cenozoic island arcs these are further subdivided into the following tectonic units e g hida oki unazuki hida gaien higo hitachi kurosegawa south kitakami nagato renge nedamo akiyoshi ultra tamba suo maizuru mino tamba chichibu chizu ryoke sanbagawa and shimanto belts the geological history of japan commenced with the breakup of the rodinia super continent at about 750 ma at about 500 ma the paleo pacific oceanic plate began to be subducted beneath the continental margin of the south china block since then proto japan has been located on the convergent margin of east asia for about 500 ma in this tectonic setting the most significant tectonic events recorded in the geology of japan are subduction accretion paired metamorphism arc volcanism back arc spreading and arc arc collision the major accretionary complexes in the japanese islands are of permian jurassic and cretaceous paleogene age these accretionary complexes became altered locally to low temperature and high pressure metamorphic or high temperature and low pressure metamorphic rocks medium pressure metamorphic rocks are limited to the unazuki and higo belts major plutonism occurred in paleozoic mesozoic and cenozoic time early paleozoic cambrian igneous activity is recorded as granites in the south kitakami belt late paleozoic igneous activity is recognized in the hida belt during cretaceous to paleogene time extensive igneous activity occurred in japan the youngest granite in japan is the takidani granite intruded at about 1 2 ma during cenozoic time the most important geologic events are back arc opening and arc arc collision the major back arc basins are the sea of japan and the shikoku and chishima basins arc arc collision occurred between the honshu and izu bonin arcs and the honshu and chishima arcs

pedogenic carbonates forms and formation processes abstract soils comprise the largest terrestrial carbon c pool containing both organic and inorganic c soil inorganic carbon sic was frequently disregarded because 1 it is partly heritage from soil parent material 2 it undergoes slow formation processes and 3 has very slow exchange with atmospheric co2 the global importance of sic however is reflected by the fact that sic links the long term geological c cycle with the fast biotic c cycle and this linkage is ongoing in soils furthermore the importance of sic is at least as high as that of soil organic carbon soc especially in semiarid and arid climates where sic comprises the largest c pool considering the origin formation processes and morphology carbonates in soils are categorized into three groups geogenic carbonates gc biogenic carbonates bc and pedogenic carbonates pc in this review we summarize the available data and theories on forms and formation processes of pc and relate them to environmental factors after describing the general formation principles of pc we present the specific forms and formation processes for pc features and the possibilities to use them to reconstruct soil forming factors and processes the following pc are described in detail earthworm biospheroliths rhizoliths and calcified roots hypocoatings nodules clast coatings calcretes and laminar caps the second part of the review focuses on the isotopic composition of pc 13c 14c and 18o as well as clumped 13c and 18o isotopes known as 47 the isotopic signature of pc enables reconstructing the formation environment the dominating vegetation 13c temperature 18o and 47 and the age of pc formation 14c the uncertainties in reconstructional and dating studies due to pc recrystallization after formation are discussed and simple approaches to consider recrystallization are summarized finally we suggest the most important future research directions on pc including the anthropogenic effects of fertilization and soil management in conclusion pc are an important part of sic that reflect the time periods and formation processes in soils a mechanistic understanding of pc formation is a prerequisite to predict terrestrial c stocks and changes in the global c cycle and to link the long term geological with short term biological c cycles

δ13c values of loess total carbonate a sensitive proxy for asian summer monsoon in arid northwestern margin of the chinese loess plateau abstract we measured carbon isotope ratio of loess total carbonates 13 cic from the jingyuan loess profile in the arid northwestern portion of the chinese loess plateau clp in order to examine the effectiveness and sensitivity of loess total carbonate 13 cic values as a potential paleoenvironmental indicator the 13 cic record in the loess profile shows large variations ranging from 1 to 7 during the past 70 ka the most negative 13 cic peaks coincide with paleosol formation s 0 l 1 ss 1 and l 1 ss 2 which occurred under relatively wetter climatic conditions during middle holocene and marine 18 o stages 3 on the other hand the least negative 13 cic values responded to loess accumulation during relative drier phases of lgm and marine 18 o stages 4 while 13 cic variations in the loess profile in arid area demonstrate a clear correlation with changes of total organic carbon isotope 13 coc of bulk sediments which has been widely used as a proxy for the past monsoon precipitation intensity the 13 cic values in the loess profile are more sensitive to the changes of paleohabitat controlled by the asian monsoon variation in the arid area we propose that carbon isotope compositions of total carbonates in loess profile can serve as a sensitive and reliable proxy for the asian summer monsoon in the arid northwestern chinese loess plateau

crustal deformation and interplate coupling in the shikoku district japan as seen from continuous gps observation abstract data from the nationwide gps continuous tracking network which has been operated by the geographical survey institute gsi of japan since april 1996 were used to study crustal deformation in the shikoku district japan the crustal deformation data are inverted to estimate interplate coupling between the subducting philippine sea phs plate and the overriding continental plate for this purpose we first extracted site coordinates from daily sinex files for the period from 1 april 1996 to 31 march 1998 and estimated average site velocities by linear regression estimated velocities under itrf96 are converted into a kinematic reference frame k heki j geophys res 101 1996 3187 3198 to discuss the crustal deformation relative to the stable interior of the eurasian eur plate to segregate the signal and noise in the thus obtained velocity vectors we employed the least squares prediction technique estimated signals displacement vectors were used to reconstruct the strains dilatations maximum shear strains principal axes of strains and to estimate the interplate coupling in the area results of crustal strains clearly portray tectonic straining of the shikoku island 1 dilatational strains show that the shikoku island is under a compressive strain regime induced by the subducting phs plate 2 maximum shear is high in the island which may be due to the oblique subduction 3 the principal axes of the strains indicate that the shikoku island is under the influence of the converging oceanic plate beneath the island in contrast the results of the inversion analysis show 1 there is a high coupled region extending from 10 to 30 km deep 2 the average back slip rate in this region reaches 43 5 mm yr and 3 the direction of the plate convergence at the nankai trough is n42 6 w

constraint of the co2 rise by new atmospheric carbon isotopic measurements during the last deglaciation 1 the causes of the 80 ppmv increase of atmospheric carbon dioxide co2 during the last glacial interglacial climatic transition remain debated we analyzed the parallel evolution of co2 and its stable carbon isotopic ratio 13co2 in the european project for ice coring in antarctica epica dome c ice core to bring additional constraints agreeing well but largely improving the taylor dome ice core record of lower resolution our 13co2 record is characterized by a w shape with two negative 13co2 excursions of 0 5 during heinrich 1 and younger dryas events bracketing a positive 13co2 peak during the bolling allerod warm period the comparison with marine records and the outputs of two c cycle box models suggest that changes in southern ocean ventilation drove most of the co2 increase with additional contributions from marine productivity changes on the initial co2 rise and 13co2 decline and from rapid vegetation buildup during the co2 plateau of the bolling allerod

dolomite abundance in chinese loess deposits a new proxy of monsoon precipitation intensity dolomite of detrital origin in carbonate rich soil can help indicate the intensity of carbonate dissolution and leaching processes using fourier transform infrared spectroscopy we generated a high resolution record of dolomite and calcite contents from eight sections on the chinese loess plateau spanning the last 130 kyr based on the relative abundance of calcite and dolomite four dissolution phases of carbonate minerals related to summer monsoon sm variations are identified as follows 1 coexistence of dolomite and calcite indicating a very weak sm with a mean annual precipitation map 725 mm

multiple expansions of c4 plant biomass in east asia since 7 ma coupled with strengthened monsoon circulation the expansion of plants using the c4 photosynthetic pathway is one of the most prominent changes in the global ecosystem during the cenozoic era a significant late miocene expansion is well documented however the existence and cause of subsequent expansions are still not clear owing in part to the lack of long continuous climate vegetation records here we present two high resolution carbon isotope time series covering the past 7 m y derived from eolian deposits on the chinese loess plateau the data indicate three intervals of significant c4 plant expansions within the semiarid monsoonal region of east asia ca 2 9 2 7 ma 1 3 0 9 ma and 0 6 ma present these expansions covary with strengthened east asian summer monsoon circulation we conclude that in east asia large scale late miocene c4 c3 vegetation changes in semiarid areas have been primarily driven by warm seasonal precipitation and temperature variations associated with changes in monsoon circulation

low frequency earthquakes and tomography in western japan insight into fluid and magmatic activity abstract low frequency lf microearthquakes are detected in the lower crust and uppermost mantle beneath western japan which may reflect fluid and magmatic activity in the subduction zone in this work we combine seismic tomography and the lf earthquakes to study the crustal and upper mantle structure and fluid and magmatic activity in western japan high resolution tomographic images under this region are determined using high quality arrival time data in kyushu the subducting philippine sea slab is detected clearly as a high velocity zone and the arc magma related low velocity low v anomalies under the active arc and back arc volcanoes are imaged clearly prominent low v zones are visible in the crust and uppermost mantle beneath the quaternary volcanoes along the japan sea coast and lf events occur actively under some of those volcanoes lf events are also detected in the source areas of the 1995 kobe earthquake m 7 2 and the 2000 tottori earthquake m 7 3 supporting the hypothesis that the large crustal earthquakes were triggered by the crustal fluids these results indicate that fluid and magmatic activities exist widely in western japan which are caused by dehydration of the subducting philippine sea slab and corner flow in the mantle wedge

negative δ18o δ13c relationship of pedogenic carbonate from northern china indicates a strong response of c3 c4 biomass to the seasonality of asian monsoon precipitation abstract evaluating how future climate changes may impact c3 c4 biomass in east asia depends largely on the understanding of the relationship between past c3 c4 variations and asian monsoon circulation the glacial interglacial variations in c3 c4 biomass have been readily ascribed to the summer monsoon however the internal processes governing the link of c3 c4 vegetation to the asian monsoon have not been clearly described here we present isotopic results of pedogenic carbonate from northern china for the holocene the last and penultimate interglacial periods comparison of the observed and predicted 18o values of modern soil carbonate from gravelly soils suggests that pedogenic carbonate forms mainly in warm rainy season carbonate nodules from the chinese loess demonstrate a distinct negative 18o 13c relationship and a wider scatter of isotopic values in the southern loess plateau than in the northern part by combining rainfall 18o of precipitation and the peak of c3 and c4 plant metabolism we develop a conceptual model to explain the isotopic signatures of the carbonate nodules our model shows that a narrowly focused season of monsoon precipitation at a specific site produces low 18o values of soil water and simultaneously favors c4 over c3 plants our model further suggests that the scattered isotopic values of soil carbonate reflect a strong summer monsoon while the focused values indicate a weak summer monsoon 13c values of soil carbonate indicate a striking pattern of northward increasing c4 vegetation for the last interglacial while a flat spatial pattern is seen for the penultimate interglacial and the holocene it is inferred that the summer monsoon was stronger during the last interglacial than during the penultimate interglacial and the holocene leading to a northward displacement of c3 forest ecosystems into the southern loess plateau in addition an in phase relationship between intra nodule 13c and 18o values suggests a strong and possibly rapid response of c3 c4 biomass to the seasonality of asian monsoon precipitation in this context if the last interglacial period mis 5 is taken as an analog for the projected near future then c3 plants may be favored in the south while c4 plants may be efficient in the north

does δ13ccarb of the chinese loess indicate past c3 c4 abundance a review of research on stable carbon isotopes of the chinese loess current research on stable carbon isotopes of the chinese loess is reviewed the stable carbon isotopic composition of soil organic matter som 13corg of paleosols formed during interglacials is more positive than that within loess accumulated during glacials spatially it becomes progressively more negative from the eastern chinese loess plateau clp to the western however stable carbon isotopic composition of pedogenic carbonates 13ccarb from the same sequence produces an opposing trend both temporally and spatially and variation differs from expectations under conditions of equilibrium this indicates that 13ccarb in the chinese loess cannot be used to reconstruct the relative proportion of c3 c4 plants in past ecological communities furthermore use of 13ccarb to reconstruct the expansion of c4 plants in older tertiary red clay deposits is considered unreliable we believe 13ccarb may act as an indirect indicator of vegetation density following on changes in moisture supply controlled by the intensity of the asian summer monsoon but conclude that full understanding of the paleoclimatic significance of 13ccarb in the chinese loess and underlying tertiary red clay requires better understanding of modern isotopic processes

use of carbon isotopes in paleosols as an indicator of the p co2 of the paleoatmosphere measurements of carbon isotopic composition of coexisting paleosol organic matter and carbonate results in improved estimates of the paleo p co2 content of the paleoatmosphere measurements from tertiary paleosols indicate that the levels of co2 in the early eocene middle and late miocene and pliocene were less than 1000 ppmv early cretaceous levels of p co2 were significantly higher of the order of 1500 to 3000 ppmv

crustal deformation and strain analysis in nepal from gps time series measurement and modeling by arma method high precision global positioning system gps measurements from 2002 to 2017 in nepal has been analyzed and modeled with autoregressive moving average arma method the measured velocities of the gps sites in itrf 2014 indicate 6 12 mm year n s convergence inside the nepal between india and tibet this convergence occurs in the southern and western border of nepal but it is negligible to the eastern border of nepal arma modeled result of india fixed velocities is able to successfully model within 0 5 mm year the current measured velocities in nepal synthetic or modeled velocities using arma method and measured velocity have difference 2 mm year at some sites this indicates the possibility of very small level of a ductile deformation in the present best fit arma model the modeled velocities 8 10 mm year convergence taken up from northern to southern boundaries of nepal indicates slip along active main himalayan thrust mht which is the cause of change in tectonic strain and may be able to trigger earthquakes inside the country dislocation modeling of active mht is also carried out in the study using gps vertical displacement the geometric model of the mht is characterized by a rectangular plane with dip angle of 9 5 and the reverse kinematics with a slip of 19 mm year the thrust is located at a depth of 20 km in addition the regional deformation of the nepal has been checked by baseline measurement and coordinate stability of gps sites for the different zones the baseline divergence and convergence of nearest gps sites have been tested using triangular sites the summary of regional deformation implies n s convergence only and rules out any type of e w convergence finally the investigation of observed and modeled strain confirms that there is no significant strain accumulation due to localized regional deformation or earthquakes specific to the active dislocations and faults this suggests that the convergence from northern to southern boundaries of nepal is associated with the slip along the mht only

c3 c4 vegetation evolution over the last 7 0 myr in the chinese loess plateau evidence from pedogenic carbonate δ13c the stable carbon and oxygen isotopic compositions of soil carbonate were measured on an eolian loess and red clay sequence at lingtai the chinese loess plateau this sequence is composed of 130 m of tertiary red clay deposits with a basal age of 7 05 ma overlain by 175 m of pleistocene loess in the field we identified ca 110 carbonate nodule horizons in the red clay and 27 nodule horizons in the loess these carbonate nodule horizons are formed by leaching and re precipitation of carbonate from the eolian material the d13c record of soil carbonate indicates a major expansion of c 4 plants at ca 4 0 myr in the loess plateau this event is comparable in timing with the expansion of c 4 plants in northern north america cerling et al 1997 nature 389 153 158 but is ca 3 million years later than the c 4 biomass expansion in pakistan quade et al 1989 nature 342 163 166 the pedogenic characteristics of the soils and the d18o record in the red clay suggest that the c 4 plant expansion in the loess plateau was not driven by local climatic changes which may support cerling et al s 1997 assertion that the decline of atmospheric co 2 levels in the neogene is responsible for this global vegetation change our record also implies that the tibetan plateau could have been uplifted to a critical height in the late miocene thus resulting in the formation of the atmospheric great east asia trough 2000 elsevier science b v all rights reserved

quantitative uncertainty analyses of ancient atmospheric co2 estimates from fossil leaves the relationship between atmospheric co 2 and ancient climate is of fundamental importance for gauging the climate sensitivity of the earth system to a changing co 2 regime one of the most widely adopted paleobiological co 2 proxies for reconstructing earth s atmospheric co 2 history exploits the inverse relationship between leaf stomatal index the fraction of leaf epidermal cells that are stomatal structures and atmospheric co 2 however fossil leaf based co 2 reconstructions make a prioii assumptions about the form of the empirical relationship between si and co 2 required for transfer functions and have failed to correctly propagate error terms these effects can translate into erroneous interpretations that undermine the value of the proxy here we report the development and application of a rigorous generalized statistical framework overcoming these limitations that generates probability density functions for each atmospheric co 2 estimate the utility of our statistical tools is demonstrated by showing how they revise earlier atmospheric co 2 estimates from fossil cuticles of ginkgo and metasequoia trees during the early eocene and middle miocene warm periods upwards by 150 to 250 ppm to 450 to 700 ppm the revised co 2 reconstructions therefore help to resolve the paradox of warm paleogene and neogene greenhouse climates co existing with near present day levels of co 2 and support the emerging view from independent paleoclimate studies for a high climate sensitivity of the earth system the statistical tools presented are sufficiently versatile to permit their use in other investigations of paleoco 2 estimates from fossil leaves

seismic imaging of southwest japan using p and pmp data implications for arc magmatism and seismotectonics abstract to better understand the relationship between crustal heterogeneity and seismotectonics and arc magmatism we determined a detailed p wave velocity structure of the crust under a north south belt area in southwest japan by using the first arriving p waves and the reflected p waves from the moho discontinuity pmp from 60 crustal earthquakes recorded by 29 seismic stations our results revealed significant low velocity anomalies beneath the fault zone of the median tectonic line and the daisen volcano which suggest that daisen is potentially an active volcano in the lower crust we detected low velocity anomalies overlying the subducting philippine sea plate which may indicate the existence of fluids released by the slab dehydration the 1955 southern tokusima earthquake m 6 4 occurred between low and high high velocity zones the 2000 western tottori earthquake m 7 3 and other nearby strong earthquakes occurred around the daisen volcano which may be related to the upwelling magma and fluids

refining the pedogenic carbonate atmospheric co2 proxy and application to miocene co2 abstract quantifying uncertainty is essential for any paleoenvironmental proxy recent work on propagating error through the equation used to determine atmospheric co 2 concentrations from paleosol carbonates yields conflicting results small magnitude uncertainty from gaussian error propagation contrasts with larger magnitude uncertainty from monte carlo error propagation the discrepancy is reconciled here by revising partial differential equations for the gaussian approach uncertainties calculated using the two approaches are compared and applied to miocene calcic paleosols monte carlo propagated errors are asymmetrical but otherwise agree with gaussian errors three methods for assigning soil respired co 2 concentrations s z to paleosols are also compared a revised calibration of depth to the bk horizon as a direct proxy for s z is presented and although it results in lower atmospheric co 2 concentrations than the original calibration it results in significantly higher calculated atmospheric co 2 than the use of mean annual precipitation as a proxy for s z or assigning s z values based on soil order averaging atmospheric co 2 concentrations calculated using soil order based s z values from 10 penecontemporaenous and independent paleosols will likely result in useful constraints on earth system sensitivity the improvement of proxies for s z is needed to increase the accuracy and precision and to resolve potential volatility in co 2 time series

using supervirtual first arrivals in controlled source hardrock seismic imaging well worth the effort varied applications of seismic interferometry have arisen in the last decade however the potential of the method to improve reflection seismic processing in hardrock environments has not explicitly been regarded therefore in this paper we investigate the potential of retrieving the first arrivals originally hindered by high noise level in the exploitation of controlled source data acquired over the iron oxide apatite rich deposit at grangesberg sweden and its mining induced structures the supervirtual first arrivals retrieved using interferometry methodologies allowed first breaks to be picked more extensively than in the original data revised static corrections significantly improved the linearity of the first arrivals and continuity of reflections in the source gathers especially reflections considerably enhanced in the source gathers stacked constructively in the final section comparison with geological data supported by traveltime forward modelling indicates that these reflections represent the unmined part of the deposit other reflections at shallower depth are interpreted as anthropogenic faults possibly located at lithological contacts tomographic inversion was also run using the augmented traveltime data the greater resolution and penetration of this new tomographic image allowed better bridging with the results of the reflection seismic section velocity anomalies depict the presence of mining induced structures and a potential brewery fault which is believed to put at risks an urban area even though the potential of first arrival retrieval seems to be case dependent this study illustrates that interferometry may substantially improve the accuracy of static corrections and subsequent stack for hardrock imaging as well as in the penetration and resolution of traveltime tomograms

rayleigh distillation and the depth profile of 13c 12c ratios of soil organic carbon from soils of disparate texture in iron range national park far north queensland australia a depth and particle size specific analysis of soil organic carbon soc and its isotopic composition was undertaken to investigate the effects of soil texture or particle size on the depth profile of stable carbon isotopic composition of soc 13csoc in two tropical soils depth specific samples from two soil profiles of markedly different texture coarse grained and fine grained were separated into particle size classes and analyzed for the mass mass concentration of soc c and 13csoc within 1 m of the soil surface 13csoc in the coarse textured soil increases by 1 3 to 1 6 while 13csoc from the fine textured soil increase by as much as 3 8 to 5 5 this increasing depth trend in the coarse textured soil is approximately linear with respect to normalized c while the increase in the fine textured soil follows a logarithmic function with respect to normalized c a model of rayleigh distillation describing isotope fractionation during decomposition of soil organic matter som accounts for the depth profile of 13csoc in the fine textured soil but does not account for the depth profile observed in the coarse textured soil despite their similar climate vegetation and topographic position these results suggest that kinetic fractionation during humification of som leads to preferential accumulation of 13c in association with fine mineral particles or aggregates of fine mineral particles in fine textured soils in contrast the coarse textured soil shows very little applicability of the rayleigh distillation model rather the depth profile of 13csoc in the coarse textured soil can be accounted for by mixing of soil carbon with different isotopic ratios

can the okhotsk plate be discriminated from the north american plate the plate geometry in northeast asia has been a long standing question with a major issue being whether the sea of okhotsk and northern japanese islands are better regarded as part of the north american plate or as a separate okhotsk plate this question has been difficult to resolve because earthquake slip vectors along the kuril and japan trenches are consistent with either pacific north america or pacific okhotsk plate motion to circumvent this difficulty we also use slip vectors of earthquakes along sakhalin island and the eastern margin of the japan sea and compare them to the predicted eurasia okhotsk and eurasia north america motions for a model with a separate okhotsk plate we invert 10 eurasia okhotsk and 255 pacific okhotsk slip vectors with pacific north america and eurasia north america nuvel 1 data alternatively for a model without an okhotsk plate those eurasia okhotsk and pacific okhotsk data are regarded as eurasia north america and pacific north america data respectively the model with an okhotsk plate fits the data better than one in which this region is treated as part of the north american plate because the improved fit exceeds that expected purely from the additional plate the data indicate that the okhotsk plate can be resolved from the north american plate the motions on the okhotsk plate s boundaries predicted by the best fitting euler vectors are generally consistent with the recent tectonics the eurasia okhotsk pole is located at northernmost sakhalin island and predicts right lateral strike slip motion on the nne striking fault plane of the may 27 1995 neftegorsk earthquake consistent with the centroid moment tensor focal mechanism and the surface faulting along the northern boundary of the okhotsk plate the north america okhotsk euler vector predicts left lateral strike slip consistent with the observed focal mechanisms on the nw boundary of the okhotsk plate the eurasia okhotsk euler vector predicts e w extension discordant with the limited focal mechanisms and geological data this misfit may imply that another plate is necessary west of the magadan region in southeast siberia but this possibility is hard to confirm without further data such as might be obtained from space based geodesy

high resolution 2d seismic imaging and forward modeling of a polymetallic sulfide deposit at garpenberg central sweden we acquired a high resolution 2d seismic profile to test the capability of the seismic method in imaging a sulfide ore body at garpenberg central sweden delineation of the geologic structures wh

multi proxy evidence for tectonic control on the expansion of c4 grasses in northwest argentina the timing of the rise of c4 grasses and the climatic conditions driving their expansion are widely debated with recent studies suggesting that the expansion was more complex than previously thought proxy reconstructions from northwestern argentina record multiple increases and decreases in c4 abundance throughout the late miocene to early pliocene as well as variations in the timing of the spread of c4 grasses into the region here we present a multi proxy paleovegetation reconstruction of the proportions of c3 and c4 vegetation using organic carbon and phytoliths preserved in paleosols at entre rios in the santa maria basin of catamarca argentina between 6 2 and 3 3 ma both corg13 and phytolith assemblages indicate a c3 dominated ecosystem with no evidence for substantial amounts of c4 vegetation from the late miocene through mid pliocene despite their rise to dominance elsewhere during this time these data suggest that by 6 2 ma the santa maria basin floor was at an elevation high enough to create locally cool conditions that allowed c3 vegetation to outcompete c4 grasses phytolith assemblages show that later uplift of the sierra calchaquies and sierra aconquija ranges through the pliocene increased aridity and drove the expansion of c3 grasses at the expense of palms and other forest indicators this multi proxy paleovegetation reconstruction demonstrates that tectonics played an important role in controlling the late miocene expansion c4 grasses by suppressing their spread into northwest argentina

reprocessing legacy three dimensional seismic data from the halfmile lake and brunswick no 6 volcanogenic massive sulphide deposits new brunswick canada we reprocessed legacy three dimensional 3d seismic data from the halfmile lake and brunswick areas both of which were acquired for mineral exploration in the bathurst mining camp new brunswick

modern soil system constraints on reconstructing deep time atmospheric co2 abstract paleosol carbonate based estimates of paleo atmospheric co 2 play a prominent role in constraining radiative forcing and climate sensitivity in the deep time large uncertainty in paleo co 2 estimates made using the paleosol carbonate co 2 barometer however arises primarily from their sensitivity to soil respired co 2 s z this parameter is poorly constrained due to a paucity of soil co 2 measurements during carbonate formation in modern soils and a lack of widely applicable proxies of paleo soil co 2 here the 13 c values of carbonate and soil organic matter som pairs from 130 holocene soils are applied to a two component co 2 mixing equation to define soil order specific ranges of soil co 2 applicable for constraining s z in their corresponding paleosol analogs equilibrium carbonate som pairs characterized by 13 c carb som values of 12 2 15 8 define a mean effective fractionation of 14 1 and overall inferred total soil co 2 contents during calcite formation of s z during calcite formation is 1500 2000 ppmv range of 500 2500 ppmv overall higher values 2000 5000 ppmv are indicated by the subset of these soils characterized by higher moisture content and productivity near atmospheric levels 400 200 ppmv of estimated s z are indicated by immature soils recording their low soil productivity vertisols define the largest range in total soil co 2 25 000 ppmv reflecting their seasonally driven dynamic hydrochemistry a s z range of 1000 10 000 ppmv is suggested for paleo vertisols for which calcite precipitation can be constrained to have occurred in an open system with two component co 2 mixing with a best estimate of 2000 ppmv 1000 ppmv appropriate for paleo vertisols for which evidence of protracted water saturation is lacking mollisol pairs define a best estimate of s z of 2500 ppmv range of 600 4000 ppmv for late cretaceous and cenozoic analogs non equilibrium pairs with 13 c values 16 make up 51 of the dataset lending support to the hypothesis that pedogenic carbonate precipitation occurs during periods of low productivity in a soil atmosphere with a large component of atmospheric co 2 predictable scaling between estimated soil co 2 and the difference in 13 c between measured pedogenic carbonate and that predicted to have formed from soil respired co 2 inferred from measured som can be used to further constrain appropriate ranges of s z for reconstruction of paleo atmospheric p co 2 soil co 2 estimates are poorly correlated to mean annual precipitation likely reflecting that for carbonate bearing soils where moisture limits co 2 production total soil co 2 is most strongly influenced by actual evapotranspiration

the 2011 magnitude 9 0 tohoku oki earthquake mosaicking the megathrust from seconds to centuries geophysical observations from the 2011 moment magnitude m w 9 0 tohoku oki japan earthquake allow exploration of a rare large event along a subduction megathrust models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places sources of high frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip relative to the m w 8 8 2010 maule chile earthquake the tohoku oki earthquake was deficient in high frequency seismic radiation a difference that we attribute to its relatively shallow depth estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event

improved structural interpretation of legacy 3d seismic data from karee platinum mine south africa through the application of novel seismic attributes abstract seismic detection of faults dykes potholes and iron rich ultramafic pegmatitic bodies is of great importance to the platinum mining industry as these structures affect safety and efficiency the application of conventional seismic attributes such as instantaneous amplitude phase and frequency in the hard rock environment is more challenging than in soft rock settings because the geology is often complex reflections disrupted and the seismic energy strongly scattered we have developed new seismic attributes that sharpen seismic reflections enabling additional structural information to be extracted from hard rock seismic data the symmetry attribute is based on the invariance of an object with respect to transformations such as rotation and reflection it is independent of the trace reflection amplitude and hence a better indicator of the lateral continuity of thin and weak reflections the reflection continuity detector attribute is based on the hilbert transform it enhances the visibility of the peaks and troughs of the seismic traces and hence the continuity of weak reflections we demonstrate the effectiveness of these new seismic attributes by applying them to a legacy 3d seismic data set from the bushveld complex in south africa these seismic attributes show good detection of deep seated thin 1 5 m thick platinum ore bodies and their associated complex geological structures faults dykes potholes and iron rich ultramafic pegmatites they provide a fast cost effective and efficient interpretation tool that when coupled with horizon based seismic attributes can reveal structures not seen in conventional interpretations

primary and secondary carbonate in chinese loess discriminated by trace element composition abstract carbonate in the eolian deposits on the chinese loess plateau carries a significant amount of information on the evolution of paleo environment however the paleo proxies based on total carbonate are largely complicated by the coexistence of primary and secondary carbonate this work provides a new method to quantify the relative proportion of primary and secondary carbonate in these eolian deposits according to the mn ca and mg ca ratios of bulk carbonate the carbonate associated mg and mn which can be extracted by selective dissolution using diluted weak acid are mostly derived from primary carbonate because the secondary carbonate contains very little mg and mn the amounts of mg and mn associated with carbonate could thus serve as proxies for the pedogenic dissolution of primary carbonate which reflect clear glacial interglacial changes of summer monsoon a positive correlation between the mn ca and mg ca ratios of bulk carbonate has been observed indicating binary mixing between secondary carbonate with the low mn ca and mg ca ratios and primary carbonate with high mn ca and mg ca ratios the high mn ca and mg ca ratios of primary carbonate endmember also indicate alxa arid lands as the main source of eolian deposits on chinese loess plateau the mn ca and mg ca ratios of carbonate could be employed as a quick method to check the purity of the secondary carbonate used for paleo environmental studies and help to interpret the paleo proxies based on the bulk carbonate the results reveal significant amount of primary carbonate included in the traditionally believed pure authigenic carbonate phases such as carbonate concretion rhizolith and the fine grain sized carbonate the new method also helps to appraise the control of the relative portion of primary and secondary carbonates on the stable carbon and oxygen isotopes of bulk carbonate high mg ca ratio and low mn ca ratio of the carbonate in red clay formation is observed which confirms the existence of authigenic dolomite

quantifying and understanding the uncertainty of atmospheric co2 concentrations determined from calcic paleosols 1 a computer program pbuq that uses monte carlo simulations to propagate uncertainty through regression equations and the equation for the paleosol carbonate co2 paleobarometer is presented pbuq includes options for all of the common approaches to determining values for input variables and incorporates several recent advancements relevant to determining values for soil respired co2 concentrations 13c values of respired co2 13c values of atmospheric co2 and temperatures of soil carbonate formation pbuq is intended to improve confidence in paleoatmospheric co2 research by helping researchers draw statistically significant conclusions pbuq can also be used to attribute and partition error among various sources and thereby advance this technique sensitivity analysis indicates that s z is the largest source of uncertainty for most paleosols and that uncertainty is minimized for soils in which co2 is an evenly balanced mixture between soil derived and atmospheric components evenly balanced mixtures are most likely for paleosols formed in deserts and for weakly developed paleosols development of proxies for soil respired co2 concentrations and 13c values of soil respired co2 specifically for such soils is perhaps the most crucial next step for improving this technique currently calcic paleosols are best used to test the significance of trends and or differences among time slices in paleoatmospheric co2 concentration application to quantifying earth system sensitivity will require large scale averaging of determinations from individual paleosols and or reduced uncertainty associated with input variables

why 3d seismic data are an asset for exploration and mine planning velocity tomography of weakness zones in the kevitsa ni cu pge mine northern finland kevitsa is a disseminated ni cu pge platinum group elements ore body in northern finland hosted by an extremely high velocity 6 5 8 5 km s ultramafic intrusion it is currently being mined at

evolution of c4 plants and controlling factors insight from n alkane isotopic values of nw indian siwalik paleosols abstract the 13c values of long chain n alkanes from paleosol samples n 74 of four nw indian siwalik sections have been used to reconstruct the relative abundance of c3 c4 plants after isotopic characterization of modern plants from the ganges floodplain considered equivalent to the past siwalik floodplain the values from the naladkhad 11 6 8 9 ma and ranital 11 3 7 4 ma sections of the kangra sub basin indicate the presence of ca 20 c4 plants at ca 11 ma the existence of c4 plants at ca 11 ma indicate an early appearance of c4 plants compared with the published data from the siwalik regions the ranital section shows a patchy occurrence of c4 plants between 11 3 ma and 7 4 ma and the jabbarkhad section shows 5 2 3 0 ma a gradual increase in c4 plant abundance the c4 plant abundance fluctuated between 83 and 0 5 8 1 3 ma in the haripur khol section of the subathu sub basin comparison of c4 plant abundance from the four sections shows that each section was characterised by a distinct evolutionary pattern the d values of the same n alkanes from the kangra and subathu sub basins indicate two episodes of indian summer monsoon intensification at ca 9 ma and ca 4 ma the correlation between dc29 and 13cc29 values varied in different sections it was also observed that the c4 plant abundance variation could be linked to the variable channel overbank ratio of the studied sections this observation suggests that indian summer monsoonal rainfall type of overbank sediments and moisture content controlled the abundance of c4 plants in the siwalik floodplain

seismic anisotropy and mantle dynamics beneath china abstract we analyzed the shear wave splitting at 138 permanent seismograph stations to study seismic anisotropy and mantle dynamics under mainland china to obtain reliable results we used three different methods to measure the shear wave splitting parameters using core phases sks skks skiks and pks as well as the direct s waves from regional and distant earthquakes our results show that the fast orientations of the anisotropy wnw ese in eastern china are generally consistent with the absolute plate motion apm direction of the eurasian plate suggesting that the anisotropy is mainly located in the asthenosphere resulting from the lattice preferred orientation of olivine due to the shear deformation there the fast axes in western china generally agree with the strikes of the orogens and active faults while they are perpendicular to the direction of the maximum horizontal stress suggesting that the anisotropy in the lithosphere contributes significantly to the observed shear wave splitting the fast axes in western china are also consistent with the apm direction suggesting that the apm driven anisotropy in the asthenosphere is another source of the shear wave splitting there these results suggest that apm driven anisotropy commonly exists under continents similar to that under oceanic regions even though the continental lithosphere has suffered extensive deformation

development of 3 d seismic exploration technology for deep nickel copper deposits a case history from the sudbury basin canada following extensive petrophysical studies and presite surveys the trill area of the sudbury basin was selected for conducting the first 3 d seismic survey for mineral exploration in north america the 3 d seismic experiment confirms that in a geological setting such as the sudbury igneous complex massive sulfide bodies cause a characteristic seismic scattering response this provides an excellent basis for the direct detection of massive sulfides by seismic methods the feasibility study suggests that high resolution seismic methods offer a large detection radius in the order of hundreds to thousands of meters together with accurate depth estimates

new constraints on using paleosols to reconstruct atmospheric pco2 ecosystem and climatic changes due to anthro po genic emissions of co 2 are of increasing importance to society one way to predict these changes in the future is to study warming events in the geologic past the main control of earth s temperature over geologic time is the concentration of atmospheric co 2 however the precise relationship between co 2 and temperature is not fully understood therefore it is essential to be able to quantify atmospheric co 2 concentrations in the geologic past especially at times of rapid climate change analogous to current atmospheric changes one widely applied proxy relates the carbon isotopic composition of pedogenic carbonates to atmospheric pco 2 but one of the key variables soil respired co 2 s z is not well constrained this study presents a new proxy where soil respired co 2 is related to mean annual precipitation map by the following equation s z 5 67 map 269 9 r 2 0 59 se 681 ppm this proxy validated for modern atmospheric pco 2 levels constrains the primary source of uncertainty in the soil carbonate paleobarometer we apply this proxy to make atmospheric pco 2 reconstructions for examples from the cenozoic mesozoic and paleozoic and calculate co 2 estimates that are in better agreement with estimates from other independent proxies and model results than previous pedogenic carbonate reconstructions the implications of the uncertainties attributed to pedogenic carbonate paleobarometry as well as guidelines for using this method are discussed by making individual measurements rather than assumptions for each isotopic value and combining those analyses with an s z estimate for each paleosol considered using our new proxy described herein we can obtain increased precision for atmospheric pco 2 reconstructions

3d seismic reflection imaging of volcanic hosted massive sulfide deposits insights from reprocessing halfmile lake data new brunswick canada three dimensional seismic reflection data from the halfmile lake area new brunswick canada was reprocessed over an 18 km2 grid to improve the seismic signatures of a 5 million ton volcanic hosted massive sulfide vhms deposit located at 1200 m depth known as the deep zone as well as key host rock structures we chose a prestack dip moveout dmo and poststack migration processing sequence to preserve the possible diffraction signature of the deep vhms zone despite the high level of source generated noise and large statics caused by near surface conditions our processing results revealed improved 3d seismic images for shallow and deep structures many of the imaged structures were easily correlated with known lithological con tacts constrained by boreholes and petrophysical measurements a short flat lying segment of high amplitude reflection at about 800 m depth in the unmigrated cube was interpreted to originate from a small portion of the lower vhms zone the dmo stack was characterized by a l

secular crustal deformation and interplate coupling of the japanese islands as deduced from continuous gps array 1996 2001 abstract data from the nation wide gps continuous tracking network that has been operated by the geographical survey institute of japan since april 1996 were used to study crustal deformation in the japanese islands we first extracted site coordinate from daily sinex files for the period from april 1 1996 to february 24 2001 since raw time series of station coordinates include coseismic and postseismic displacements as well as seasonal variation we model each time series as a combination of linear and trigonometric functions and jumps for episodic events estimated velocities were converted into a kinematic reference frame heki k 1996 horizontal and vertical crustal movements from three dimensional very long baseline interferometry kinematic reference frame implication for reversal timescale revision j geophys res 101 3187 3198 to discuss the crustal deformation relative to the stable interior of the eurasian plate a least squares prediction technique has been used to segregate the signal and noise in horizontal as well as vertical velocities estimated horizontal signals horizontal displacement rates were then differentiated in space to calculate principal components of strain dilatations maximum shear strains and principal axes of strain clearly portray tectonic environments of the japanese islands on the other hand the interseismic vertical deformation field of the japanese islands is derived for the same gps data interval the gps vertical velocities are combined with 31 year tide gage records to estimate absolute vertical velocity the results of vertical deformation show that 1 the existence of clear uplift of about 6 mm yr in shikoku and kii peninsula whereas pattern of subsidence is observed in the coast of kyushu district this might reflect strong coupling between the philippine sea plate and overriding plate at the nankai trough and weak coupling off kyushu 2 no clear vertical deformation pattern exists along the pacific coast of northeastern japan this might be due to the long distance between the plate boundary japan trench and overriding plate where gps sites are located 3 significant uplift is observed in the southwestern part of hokkaido and in northeastern tohoku along the japan sea coast this is possibly due to the viscoelastic rebound of the 1983 japan sea mw 7 7 and the 1993 hokkaido nansei oki mw 7 8 earthquakes and or associated with distributed compression of incipient subduction there we then estimate the elastic deformation of the japanese islands caused by interseismic loading of the pacific and philippine sea subduction plates the elastic models account for most of the observed horizontal velocity field if the subduction movement of the philippine sea plate is 100 locked and if that of the pacific plate is 70 locked however the best fit for vertical velocity ranges from 80 to 100 coupling factor in southwestern japan and only 50 in northeastern japan since horizontal data does not permit the separation of rigid plate motion and interplate coupling because horizontal velocities include both contributions we used the vertical velocities to discriminate between them so we can say there is strong interplate coupling 80 100 over the nankaido subduction zone whereas it is about 50 only over the kurile japan trench

incorporation of trace metals into microcodium as novel proxies for paleo precipitation abstract trace element compositions of microcodium are applied for the first time as possible paleo proxies based on a case study on the chinese loess plateau clp the mg ca and sr ca ratios of the microcodium picked from the holocene paleosol across the clp show distinct positive correlation over large range of nearly one order of magnitude higher mg ca and sr ca ratios of microcodium are recorded in the sites on the northwestern clp where less monsoonal rainfall is received similar large variation of the positively correlated mg ca and sr ca ratios has also been observed for the stream water on the clp with the same spatial pattern the mg ca and sr ca ratios of the microcodium seem to be largely controlled by the composition of soil solution as reflected by stream water rather than partition coefficient rayleigh distillation and thus evolving composition of soil solution as a result of progressive precipitation of secondary calcite is responsible for the large variation and positive correlation of the mg ca and sr ca ratios for both the microcodium and stream water we propose that the bio remains in chinese loess may become inactive when the soil water is extracted to a degree and then be calcified into microcodium by the infiltration of freshwater that is mixed with the highly evolved soil solutes thus the mg ca and sr ca ratios of microcodium may record the paleo precipitation amount by reflecting the mixing ratio between the highly evolved soil solutes with higher mg ca and sr ca ratios and the fresh soil water with lower mg ca and sr ca ratios

interplate seismogenic zones along the kuril japan trench inferred from gps data inversion stress accumulation between earthquakes results from slip that is insufficient to fully accommodate plate movement an inverse analysis of gps data from the kuril japan trench reveals a trench parallel belt of stress accumulation with six peaks in the depth range of 10 40 km suggesting potential source regions for future earthquakes in the subduction zones around japan where four plates interact with one another large earthquakes have occurred repeatedly1 these interplate earthquakes are part of the process of tectonic stress accumulation and release that is driven by relative plate motion2 3 4 stress accumulation between earthquakes results from slip deficit slip that is insufficient to fully accommodate plate movement for the prediction of large earthquakes it is therefore important to monitor the distribution of slip deficit on plate interfaces here we apply an inversion method based on bayesian modelling using direct and indirect prior information on the magnitude and distribution of fault slip5 to horizontal and vertical velocities from global positioning system data for the seismically calm period between 1996 and 2000 we obtain a precise distribution of slip deficit rates on the interface between the north american and pacific plates around japan which reveals a trench parallel belt of slip deficit with six peaks in the depth range of 10 40 km these peaks agree with the source regions of past large interplate earthquakes along the kuril japan trench we conclude that the slip deficit zones identified with our method are potential source regions of large earthquakes

targeting nickel sulfide deposits from 3d seismicreflection data at kambalda australia abstractthe greenstone belts of the yilgarn craton western australia host numerous archaean gold nickel and iron ore deposits these deposits typically are found in complex geologic structures hidden by a deep heterogeneous and often conductive regolith profile this added complexity limits the depth of penetration for the potential field methods but at the same time opens new revenue possibilities through the application of seismic methods to explore this opportunity we acquired high resolution experimental 3d seismic data over lake lefroy in kambalda western australia the main objective was to map exceptionally complex deep structures associated with kambalda dome survey design used 3d ray tracing to improve the distribution of the common reflection points across ultramafic basalt contacts which host numerous small high grade nickel sulfide deposits a combination of small explosive sources high shot receiver density and exceptionally good coupling over the ultrasalty lake surface prod

climate controls on spatial and temporal variations in the formation of pedogenic carbonate in the western great basin of north america pedogenic carbonate is common in arid and semiarid soils and though its stable c and o isotope composition has been shown to reflect local environmental conditions questions remain about the quantitative nature of this relationship and the implications for paleoclimate applications to further address these questions a climosequence of four holocene soils in fish lake valley nevada western united states was instrumented and examined over the course of more than a year the annual precipitation along the transect ranges from 80 mm yr 1 to 220 mm yr 1 results show that the c and o stable isotope compositions of soil co 2 h 2 o and carbonate change systematically with elevation and climate however there was considerable temporal variability in the conditions that affected carbonate isotope values at the lowest elevation co 2 13 c and h 2 o 18 o values were similar to that in equilibrium with carbonate nearly year round at the midelevation sites spring through summer co 2 13 c and h 2 o 18 o values appeared to most closely match the 13 c and 18 o values of pedogenic carbonate at the highest elevation the c and o isotopes of carbonate did not reflect the soil co 2 13 c and h 2 o 18 o values measured during the period of study but they did appear to reflect soil respiration rates during the late spring the transect shows that arid soil carbonate 13 c values strongly reflect variations in soil respiration rates and the resulting concentrations of soil co 2 these results also indicate that depth profile sampling may be required to adequately constrain respiration rates which affect the interpreted atmospheric co 2 concentrations

high strain rate zone in central honshu resulting from the viscosity heterogeneities in the crust and mantle abstract a linear zone with high strain rates along the backarc side of central honshu the so called niigata kobe tectonic zone has been revealed by the dense gps array geonet operated by the geographical survey institute of japan in order to explore the origin of this zone we examine rheological heterogeneities in the crust or mantle above a subducting slab which possibly contribute to the high strain rates we calculate velocity profiles at the surface of the upper plate due to loading and unloading of the subducting philippine sea plate using a 2 dimensional finite element method from the numerical experiments we find that the high strain rates can be reproduced by viscosity heterogeneities either in the crust or the mantle if viscosity heterogeneity in the crust is an origin the conditions to be satisfied are i an effective elastic thickness of 5 km for short term loading 10 2 10 3 yr ii a low viscosity 19 pa s in the lower crust beneath the zone with a normal viscosity 10 21 pa s in the ambient lower crust and iii a uniform viscosity of 10 19 pa s in the upper mantle on the other hand if viscosity heterogeneity in the mantle is an origin the conditions to be satisfied are i an effective elastic thickness of 30 km for short term loading ii a low viscosity 10 18 pa s at least down to a depth of 60 km in the zone and to a depth of 10 km further seaward below the moho depth and iii a viscosity of 10 20 pa s in the ambient mantle the crust heterogeneity model contradicts the 15 km cut off depth of intraplate seismicity and the 20 km effective elastic thickness previously inferred from gravity and topography in central honshu the fact that quaternary active faults and intraplate earthquakes are not particularly concentrated in the zone also favours the mantle viscosity heterogeneity model thus we prefer the mantle heterogeneity model we suggest that upward movement of water dehydrated from the subducting philippine sea and pacific plates partial melting of the mantle above the pacific plate and serpentinization in the wedge mantle above the philippine sea plate are possible origins of the low viscous upper mantle possible low viscosities in the upper mantle wedge presented in this study seem to provide important constraints for subduction processes of oceanic plates and strain accumulation processes in the upper plate

seismic reflection imaging over a massive sulfide deposit at the matagami mining camp quebec a 2 d seismic reflection profile was shot across the southern flank of the matagami mining camp almost directly above the recently discovered bell allard massive sulfide deposit now estimated at more than 6 million metric tons all orebodies found in the southern part of the mining camp including bell allard are located at the contact between the primarily basaltic wabassee group and the underlying rhyolitic watson lake group seismic reflections were recorded from the basalt rhyolite contacts of the lower wabassee group as well as from gabbro sills that intrude much of the volcanic stratigraphy a strong reflection from the top of the bell allard orebody was also detected but the reflection does not extend over the full width of the deposit as defined by drilling appearing to correlate with the lower pyrite rich zone faulting which can be interpreted from discontinuities in the observed reflections probably controlled the formation of the bell allard deposit if the interpreted gabbro sills are accepted as isotime markers then faulting of the deeper sill complex defines a series of half grabens within the rhyolitic watson lake group the bell allard deposit is found at the intersection of one of these apparently low angle normal faults with the top of the watson lake group indicating that sulfide mineralization may have been associated with fluid flow along the fault which likely penetrates to the underlying mafic intrusion although the precise geometry of subsurface faulting cannot be estimated from a single 2 d seismic profile these results indicate that a full 3 d seismic survey should allow the mapping of many of the subsurface fault systems and the verification of hypotheses of fault controlled deposit formation

seismic imaging of massive sulfide deposits part ii reflection seismic profiling seismic reflection profiling the dominant geophysical method for hydrocarbon exploration has the potential to provide images of regional structure for mineral exploration in the crystalline crust and direct detection of large massive sulfide orebodies previous tests of traditional seismic methods in hard rock environments have had mixed success based on these earlier results we have tailored acquisition and processing strategies to conditions in the canadian shield we illustrate these methods using an example from the sudbury basin a rich mineral producing region because of structural complexity that complicates interpretation of the seismic images the seismic data are integrated with detailed three dimensional forward modeling based on physical properties studies mine geology and well logging through this integrated approach we show that massive sulfides can produce a characteristic seismic reflection response and that surface seismic reflection profiling may be used to detect and delineate deep large massive sulfide deposits accurately in a complex geologic setting characterized by moderate dips

contemporary deformation and seismicity analysis in southwest japan during 2010 2018 based on gnss measurements a significant amount of work has been conducted in the japanese islands on high precision positioning surveying natural disaster mitigation reference frame and datum definitions however there is substantial scope for exploring the current seismotectonic activity of japan which would provide further awareness of disaster management the short recurrence time of great inter plate earthquakes and well recorded geodetic observations provide one of the best examples to analyze the combination of contemporary deformation and seismic intensity in southwest sw japan in the current study we analyzed three districts of sw japan which include mainly kyushu district and parts of chugoku and shikoku districts we predicted global navigation satellite system gnss measurements based on amurian fixed reference frame aref velocities with the help of singular spectrum analysis ssa method and examined the regional deformation from april 01 2010 to december 31 2018 in addition we analyzed the earthquakes clustered calculated by the nearest neighborhood distance method which showed prominently bimodal seismicity of sw japan and revealed the existence of two statistically distinct earthquake populations the events inside a cluster were normally close to their nearest neighbors whereas events from distinct clusters were comparatively aloof from each other finally the paper provides the spatial strain and rotational rate variation for selected seismotectonic districts that are in relatively good agreement with the seismic deformation inferred from earthquake focal mechanisms we believe that our integrated approaches would provide a better insight into the active deformation of sw japan

atmospheric carbon dioxide linked with mesozoic and early cenozoic climate change carbon isotopes of fossil plants and model simulations suggest that atmospheric carbon dioxide levels were variable during the period 200 to 60 million years ago the large decreases in the partial pressure of co2 coincide with glaciations providing evidence against climate co2 decoupling during the mesozoic

continuous gps array and present day crustal deformation of japan a gps array with about 1 000 permanent stations is under operation in japan the gps array revealed coseismic deformations associated with large earthquakes and ongoing secular deformation in the japanese islands based on daily coordinate data of the gps stations strain rate distribution is estimated most regions with a large strain rate are related to plate boundaries and active volcanoes in addition the niigata kobe tectonic zone nktz is recognized as a region of large strain rate along the japan sea coast and in the northern chubu and kinki districts this newly found tectonic zone may be related to a hypothetical boundary between the eurasian or amurian and the okhotsk or north america plates precise observation of crustal deformation provides important boundary conditions on numerical modeling of earthquakes and other crustal activities appropriate computation methods of continuous deformation field are directly applicable to data assimilation for such numerical simulations

seismic methods in mineral exploration and mine planning a general overview of past and present case histories and a look into the future abstractdue to high metal prices and increased difficulties in finding shallower deposits the exploration for and exploitation of mineral resources is expected to move to greater depths consequently seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration these methods also can be used with varying degrees of success to directly target mineral deposits at depth we review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions australia europe canada and south africa a wide range of case studies are covered including some that are published in the special issue accompanying this article from surface to borehole seismic methods as well as petrophysical data and seismic modeling of mineral deposits at present high resolution 2d surveys mostly are performed in mining areas but there is a general increasing trend in the use of 3

geodynamics of the baikal rift zone and plate tectonics of asia the baikal rift zone stretches from the southern termination of lake baikal as far as 118 e and includes the baikal basin and the barguzin upper angara and muysk grabens that form its easterly continuation coincident with the rift zone is a narrow seismic belt which extends further east along the stanovoy range to the okhotsk sea this belt can be considered as the boundary between the eurasian and amurian lithospheric plates earthquake focal mechanism solutions that show a consistent orientation of extensional axes across the strike of the rift zone indicate the behaviour of the eurasian and amurian plates as rigid bodies from 83 focal mechanism solutions the pole of rotation of the eurasian and amurian plates was computed to lie at the point 56 95n 117 45e the angular rate estimated from the amount of baikal opening is about 1 10 7 deg year the position of the pole at the eastern termination of the rift zone accounts for the dying out of the rift zone and for the appearance east of the pole of compressive structures in the stanovoy range to the southwest the baikal rift zone is replaced by the mosaic of microplates in central asia that occupy the space between the eurasian and indian lithospheric plates prominent are the mongolian dzungarian alashan tarim tibetan and pamir microplates earthquakes in central asia are dispersed although higher concentrations of earthquakes associated with microplate boundaries are prominent the tectonics of central asia are considered to be due to the interaction of rigid microplates assuming that plastic deformations occur within the relatively wide zones along the microplate boundaries by considering the strike slip faults to define the trajectories of microplate motions the parameters of relative movements of the microplates have been computed the microplate mosaic of central asia is moving northeasterly as a result of the collision and continued convergence of india and eurasia the mosaic acts as a wedge splitting off the amurian plate from eurasia causing it to rotate counterclockwise so opening the baikal rift

crustal deformation in kyushu derived from geonet data 1 an investigation was conducted on the horizontal crustal deformation in kyushu using the coordinate data from gps earth observation network geonet for the 4 years from 1998 to 2002 for which the annual variations are corrected we examined the spatial differences in the displacement rate relative to the amurian plate by subtracting the velocity of the amurian plate at each of the global positioning system gps stations models for interplate coupling in hyuganada and the dilatational source beneath sakurajima are obtained the crustal deformation in eastern kyushu is well explained by the model of interplate coupling in hyuganada which is strong in the north and weak in the south when the effects of the interplate coupling and the dilatational source are removed a southward extensional field is recognized in and to the south of the beppu shimabara graben in western kyushu in southern kyushu to the south of around latitude 32 n a southeastward movement is conspicuous it must be noted that the displacement field is extensional indicating that southern kyushu is being dragged at the base by a flow in the mantle not moving like a raft on the flow it is probable that the flow in the mantle is driven by the rising of hot materials in the okinawa trough and a retreat of the trench where the philippine sea plate is subducting a gap in the magnitude of the eastward displacement rate around latitude 32 n implies that the velocity of the flow in the mantle decreases substantially to the north of the line the beppu shimabara graben may be a continuation of the okinawa trough but the significant southwestward displacement rate observed in the eastern part suggests that the deformation in the graben at least to the east of aso volcano is affected by the westward movement of the forearc sliver produced by the oblique subduction of the philippine sea plate on the nankai trough off shikoku island we think that the strong coupling in the bungo channel in our model is probably not real but might be a result of our assumption that all the westward displacements in northeastern kyushu a part of which are actually due to the movement of the forearc sliver are produced by interplate coupling

potential of legacy 2d seismic data for deep targeting and structural imaging at the neves corvo massive sulphide bearing deposit portugal abstract seismic methods are becoming an established choice for deep mineral exploration after being extensively tested and employed for the past two decades to investigate whether the early european mineral exploration datasets had potential for seismic imaging that was overlooked we recovered a low fold legacy seismic dataset from the neves corvo mine site in the iberian pyrite belt in southern portugal this dataset comprises six 4 6 km long profiles acquired in 1996 for deep targeting using today s industry scale processing algorithms the world class ca 150 mt lombador massive sulphide and other smaller deposits were better imaged additionally we also reveal a number of shallow but steeply dipping reflections that were absent in the original processing results this study highlights that legacy seismic data are valuable and should be revisited regularly to take advantage of new processing algorithms and the experiences gained from processing such data in hard rock environments elsewhere remembering that an initial processing job in hard rock should always aim to first obtain an overall image of the subsurface and make reflections visible and then subsequent goals of the workflow could be set to for example understanding relative amplitude ratios the imaging of the known mineralization implies that this survey could likely have been among one of the pioneer studies in the world that demonstrated the capability of directly imaging massive sulphide deposits using the seismic method

deep reflection seismic imaging of iron oxide deposits in the ludvika mining area of central sweden abstract reflection seismic data were acquired within two field campaigns in the blotberget ludvika mining area of central sweden for deep imaging of iron oxide mineralization that were known to extend down to 800 850 m depth the two surveys conducted in years 2015 and 2016 one employing a seismic landstreamer and geophones connected to wireless recorders and another one using cabled geophones and wireless recorders aimed to delineate the geometry and depth extent of the iron oxide mineralization for when mining commences in the area even with minimal and conventional processing approaches the merged datasets provide encouraging information about the depth continuation of the mineralized horizons and the geological setting of the study area multiple sets of strong reflections represent a possible continuation of the known deposits that extend approximately 300 m further down dip than the known 850 m depth obtained from historical drilling they show excellent correlation in shape and strength with those of the blotberget deposits furthermore several reflections in the footwall of the known mineralization can potentially be additional resources underlying the known ones the results from these seismic surveys are encouraging for mineral exploration purposes given the good quality of the final section and fast seismic surveys employing a simple cost effective and easily available impact type seismic source

evaluation of the 2d reflection seismic method toward the exploration of thrust controlled mineral deposits in southwestern fujian province china southwest of fujian is one of main ore districts of china thrust controlling mineral deposits model over there means that there may be deep concealed deposits in the overlapping areas of the thrust and refection seismic which has great depth penetration and higher resolution has great potential to delineate these complex structure and give some clues to mineralization in 2015 an experimental 13 8 km 2d reflection seismic survey named fujian 2d was conducted in this region for the data acquisition the designed shot and receiver intervals were 60 m and 20 m respectively and all 691 receivers recorded seismic signals for each shot due to the properties of the tested environment some shot points were re designed but the average fold reached 64 in the middle at more than 10 km distance during the data processing procedure conventional technologies involving statics noise elimination deconvolution and iterative velocity analyses were applied after the pre stack time migration failed to obtain a

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

structural controls on nickel sulphide ore shoots in archaean komatiite kambalda wa the volcanic trough controversy revisited abstract structural evaluation of the extensive exploration database for the kambalda tramways area archaean yilgarn craton western australia is addressing the long outstanding issue of whether the trough structure embayments that partly confine the nickel sulphide nis ore shoots are volcanic or tectonic in origin the trough structures are complex linear domains associated with talc carbonate alteration overprinting thickened komatiite overlying footwall basalt two end member trough structure types are recognised 1 re entrant trough structures and 2 open trough structures the re entrant trough structures are narrower at the top than at the base strongly asymmetric in cross section restricted in distribution to kambalda dome and transgress and truncate ore the open trough structures are wider at the top than at the base weakly asymmetric in cross section prevalent outside kambalda dome and are mineralised along their lateral margins in addition to trough associated ore other nis ore shoots overlie near planar komatiite basalt contacts and are overlain by serpentinite with relict igneous textures all these features indicate the possibility that the trough structures reflect structural folding thickening and alteration at rock contacts marking different competency during regional fold thrusting consequently nis exploration strategies should consider structural and metamorphic features as well as volcanologic and stratigraphic features recognition of folding and thrusting patterns related to major competency contrasts in favourable komatiite basalt stratigraphy near the crest of regional anticlines and domes would aid exploration success

late pliocene pleistocene expansion of c4 vegetation in semiarid east asia linked to increased burning plants using the c 4 photosynthetic pathway commonly tropical and subtropical grasses increased in abundance in east asia dur ing the late cenozoic determining the exact timing and likely fac tors leading to this major vegetation change requires region specific studies here variations in pyrogenic carbon mass accumulation rate pyc mar and isotope composition 13 c pyc from an 7 m y long depositional sequence from the central loess plateau china suggest increased biomass burning and an increased contribution to combusted material from c 4 taxa from 2 6 ma changes in the composition of pyc after 0 6 ma likely reflect the effects of lower temperatures particularly during glacial periods and changes in seasonality of precipitation increased pyc mar without concomi tant changes in 13 c pyc at ca 0 15 ma appears to indicate a decou pling of feedbacks between changes in climate fire regime and veg etation and may mark the onset of anthropogenic burning in the region these new data suggest that c 4 taxa were present on the loess plateau from at least the late miocene rising to prominence at ca 2 6 ma following changes in climate and critically an increase in biomass fires

seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central new mexico usa in order to better calibrate pedogenic carbonate as a proxy for past environments we compared the stable isotopic composition of soil co 2 soil water and pedogenic carbonate in young soils from central new mexico usa seasonal changes in the 13 c value of soil co 2 the 18 o value of soil water and the soil temperature were monitored to establish the timing of isotopic equilibrium with the carbonate calcite solubility was calculated from measured temperatures and co 2 concentrations in the soil this approach allowed us to determine the conditions associated with pedogenic carbonate formation carbon isotope equilibrium oxygen isotope equilibrium and minimum calcite solubility all occurred simultaneously during warm dry conditions in may 2008 when soil co 2 concentrations were low it is therefore concluded that pedogenic carbonate forms during warm dry periods and does not record mean growing season conditions as typically assumed the seasonal bias in pedogenic carbonate formation may explain the occurrence of pedogenic carbonate in monsoon climates and its absence in regions where annual precipitation is more uniformly distributed the implications of the seasonal bias for stable isotope based paleoenvironmental reconstructions are that paleoelevations may have been previously over or underestimated paleoatmospheric co 2 concentrations likely have been signifi cantly overestimated and pedogenic carbonate provides a c 4 biased record of paleovegetation especially in dry soils

structural insights from geodetic global positioning system measurements in the darjiling sikkim himalaya abstract deformation in active convergent wedges like the himalaya occurs over different time and space scales requiring integrated datasets for holistic insights into wedge scale deformation a new long time series 1998 2009 of geodetic static global positioning system gps dataset suggests that active deformation in the darjiling sikkim himalaya dsh is not confined to the himalayan front as previously believed instead the 9 mm yr n s active convergence here is divided almost equally within the lesser himalayan duplex lhd and the higher himalaya due to aseismic reverse slip of 18 mm yr on the himalayan decollement main himalayan thrust mht dipping 6 006 and locked at 16 km depth slip transfer along the mht causes minor to moderate earthquakes at the brittle ductile transition in the dsh measured east velocities show no systematic variation indicating that strike slip seismicity though dominant in the region does not alleviate the decollement mht seismic hazard continued slip along the mht therefore will cause a great decollement earthquake in the region also gps velocities vary in the eastern and western dsh suggesting segmentation of the himalayan arc along a transverse fault over geological to decadal time scales our integrated approach can provide better insight into active deformation in convergent wedges worldwide

a large intraplate earthquake triggered by latent magmatism 1 a magnitude mj 7 3 intraplate earthquake occurred in the western tottori area southwest japan on 6 october 2000 where there was no apparent prefaulting subsurface indication of the source fault of the 2000 earthquake magnetotelluric soundings were taken in and around where the aftershocks occurred in order to image three dimensional electrical resistivity structure at depths of up to 40 km which could indicate an anomalously conductive body in the middle crust to the upper mantle on the southwestern side of the source fault free gas and dissolved gases collected from groundwater wells around the seismic source region are characterized by 3he 4he ratios several times higher than the atmospheric value the highest value of 5 1ra is similar to those of typical arc related volcanic gases although alkali basalts of early pleistocene age are sparsely distributed in the western tottori area the observed 3he 4he ratios are higher than the calculated 3he 4he ratio derived from the ancient magmatism considering postextrusive radiogenic ingrowth of 4he by decay of u and th included in the magma therefore it is concluded that the geophysical anomaly imaged to the southwest of the source fault is attributed to latent magmatism in the present day subduction system aqueous fluids separated from the cooling crustal magma could cause deep low frequency earthquakes around the moho discontinuity and migrate into the brittle upper crust in addition the presence of aqueous fluid is expected to weaken the crustal materials locally anelastic deformation implying notable compressive deformation in the e w direction was observed in the region where aftershocks were distributed under overpressure conditions the existing fault could serve as a pathway for aqueous fluids expelled from magma with high 3he 4he ratios so the upwelling of overpressurized fluids toward the earth s surface results in the emanation of groundwaters with high 3he 4he ratios along the trace of the source fault segments

geomaterial segmentation method using multi dimensional frequency analysis based on electrical resistivity tomography abstract the determination of specific geotechnical materials in complex geotechnical environment is of great significance for engineering construction and geological disaster risk management such as karst cave fracture zone etc as a fast and convenient field test method electrical resistivity tomography is extensively applied in geotechnical engineering investigation the resistivity distribution of underground rock mass and soil can be obtained after inversion of apparent resistivity to quantitatively determine the resistivity threshold of specific geotechnical materials we referred to the multi dimensional frequency analysis and threshold determination algorithm of image segmentation based on the structural similarity between resistivity grid data and image pixels the frequency distribution of resistivity data is analyzed from two dimensions of resistivity magnitude and neighbouring difference the neighbouring difference is introduced to describe the variation degree of resistivity in space and otsu algorithm is adopted to determine resistivity threshold to identify certain kind of geotechnical material in order to verify the validity of material segmentation method two cases under rock mass condition and soil condition are studied respectively for goaf in rock mass multi dimensional frequency analysis can effectively show the frequency components of void resistivity for ancient soil landslide with narrow distribution range of resistivity multi dimensional frequency analysis can not only determine the resistivity threshold of soil sliding body quantitatively but also determine the materials with small proportion in whole area such as sliding zone according to the correlation between neighbouring difference and material properties

crustal deformation across and beyond the los angeles basin from geodetic measurements we combine 6 years of global positioning system gps data with 20 years of trilateration data and a century of triangulation taped distance and astronomic azimuth measurements to derive 66 interseismic station velocities in the greater los angeles region we interpolate the velocities to construct a regional strain rate map beyond the los angeles basin our results generally agree with the model proposed by the working group on california earthquake probabilities in 1995 important regional findings of this study are as follows 1 there is a significant n s convergence and e w extension about 0 22 and 0 17 0 05 strain yr respectively for the two components along the southern frontal fault system of the san gabriel mountains 2 the crustal deformation around the big bend of the san andreas fault saf cannot be explained solely by wrench style motion across the saf remaining motion could be part of a nw se extension which is the response to nfsw compression in the central transverse ranges region alternatively it could be caused by left lateral faulting on an oblique blind thrust beneath the san gabriel mountains 3 low strain rates axe found along the elsinore fault and newport inglewood 4 north south compression decreases from the raymond hill fault westward to the santa monica fault there is little east west extension along this fault system

strengthened east asian summer monsoons during a period of high latitude warmth isotopic evidence from mio pliocene fossil mammals and soil carbonates from northern china the east asian monsoons have fluctuated in concert with high latitude warmth during the past several hundred thousand years with humid summer monsoon dominant climates characterizing warm intervals including interglacials and interstadials and arid winter monsoon dominant climates characterizing cool intervals including glacials and stadials of the states comprising the mid pleistocene to recent climatic regime interglacials are most similar in terms of high latitude ice volumes and temperatures to those extant during the late miocene and early pliocene thus an important question is whether mio pliocene climates in northern china were analogous to a hypothetical prolonged interglacial state with increased summer monsoon precipitation and expansion of forest and steppe environments at the expense of desert environments we utilize new and previously published carbon isotopic data from fossil teeth and soil carbonates to place constraints on paleovegetation distributions and to help infer the behavior of the monsoon system between 7 and 4 ma we find that plants using the c 4 photosynthetic pathway which today are largely grasses found in regions with warm season precipitation were present in northern china by late miocene time demonstrating that the c 4 expansion in china was not significantly delayed compared to the global c4 event during the late miocene early pliocene interval soil carbonate and tooth enamel 13 c data indicate 1 that nearly pure c 3 plant ecosystems existed in the southern chinese loess plateau clp and therefore ecosystems there were dominated by woody dicot herbaceous dicot or cool season grass vegetation or a combination of these and 2 that the clp was characterized by a pattern of northward increasing c 4 vegetation and aridity utilizing a broadened conceptual model for interpreting 13 c data and citing independent faunal floral and lithostratgraphic data we suggest that these patterns reflect northward expansion of forest and steppe ecosystems and relatively humid monsoon climates during the late miocene and early pliocene an important implication of this interpretation is that the forcing mechanism illuminated by the temporal correlation during the pleistocene between warm high latitudes and strong east asian summer monsoons is a robust feature of the eurasian tectonic climatic system that predates the plio pleistocene climatic reorganization