the high pore pressures within embankment dams an unsaturated soil approach pore pressures substantially higher than expected are frequently measured within the cores of large dams typical observations are presented and various hypotheses proposed to explain this phenomenon are summarized and briefly discussed the hypothesis suggested herein is that the pore pressures are influenced by the free gases trapped during the submergence these gases are compressed at the ambient pore pressure which is decreasing in the flow direction the degree of saturation and therefore the permeability decrease in the same direction the pore pressures are thus higher than predicted in a uniform permeability condition free gases are dissolved in the water due to the increase of the pore pressures they are carried in the seepage flow and come out of solution in the core or finally in the downstream filter after some decrease of the pore water pressures the increase of pore pressure with respect to the steady state conditions is a function of many factors and is necessarily transient key wo

an amoeboid olivine inclusion aoi in ck3 nwa 1559 comparison to aois in cv3 allende and the origin of aois in ck and cv chondrites an amoeboid olivine inclusion in ck3 nwa 1559 0 54 1 3 mm consists of a diopside rich interior approximately 35 vol and an olivine rich rim approximately 65 vol it is the first aoi to be described in ck chondrites the apparent paucity of these inclusions is due to extensive parent body recrystallization the aoi interior contains irregular 3 15 m sized al bearing diopside grains approximately 70 vol 2 20 m sized pores approximately 30 vol and traces of approximately 2 m plagioclase grains the 75 160 m thick rim contains 20 130 m sized ferroan olivine grains some with 120o triple junctions a few coarse 25 50 m sized patches of plagioclase with 2 18 m thick diopside rinds occur in several places just beneath the rim the occurrence of olivine rims around aoi 1 and around many aois in cv3 allende suggests that ck and cv aois formed by the acquisition of porous forsteritic rims around fine grained rimless cais that consisted of diopside anorthite melilite and spinel individual aois in carbonaceous chondrites may have formed after transient heating events melted their olivine rims as well as portions of the underlying interiors in aoi 1 coarse plagioclase grains with diopside rinds crystallized immediately below the olivine rim secondary parent body alteration transformed forsterite in the rims of cv and ck aois into more ferroan olivine some of the abundant pores in the interior of aoi 1 may have formed during aqueous alteration after fine grained melilite and anorthite were leached out chondrite groups with large chondrules tend to have large aois aois that formed in dust rich nebular regions where cv and ck chondrites later accreted tend to be larger than aois from less dusty regions

dating of faults and estimation of surface uplift and erosion rates in the northern margin of dabie mountains china abstract absolute timing of fault movement provides information about tectonic deformation history the k ar dating method has been applied to determine the absolute timing of fault movement the key to k ar dating of fault gouge is to verify that the illite is of authigenic origin here we show effective and convincing evidences for authigenic illite in fault gouge the characteristics of the authigenic illite reveal that the host rocks were under near surface environment during fault activities the result indicates fault movement in late cretaceous in the northern margin of dabie mountains orogenic belt according to the absolute timing the uplift and erosion rates of the northern margin of dabie mountains are also estimated

microstructures mineral chemistry and geochronology of white micas along a retrograde evolution an example from the aar massif central alps switzerland abstract this study investigates gneissic tectonites of different mechanical origins and aims at unravelling the link between microstructures white mica chemistry and k ar data the highest temperature mylonitic deformation which is investigated is dominated by dislocation creep in monomineralic quartz and viscous granular flow in polymineralic domains these mylonites show homogenous mineral chemistry resulting in robust and consistent k ar age data the lowest temperature deformation investigated is that of a retrograde brittle deformation producing cohesionless fault gouges within the cohesionless fault gouges frictional granular flow is considered as the main deformation mechanism the k bearing phases inside the fault gouges record no chemical resetting during this brittle overprint but contain mechanically fragmented k bearing micas and significant amounts of newly produced smectite this yields k ar ages inside of a gouge that are in the range of adjacent mylonite ages and may not represent the timing of gouge formation in an effort to understand these uncertainties in k ar ages detailed observations of the microstructural context of k bearing white mica were made microstructural criteria in combination with quantitative element mapping allowed for the discrimination of five important mica related processes 1 fracturing recrystallization of white mica 2 re precipitation of new fine grained white mica inside the deforming rock matrix 3 pseudomorphic replacement of precursor minerals by white mica and chlorite 4 pseudomorphic replacement of pre existing white mica without grain size reduction and 5 remnant grains the combination of these different processes led to a high variability in mineral chemistry and isotope data for tectonites which relates directly to variations in the size of the equilibrium volumes despite the samples being highly deformed in the presence of fluids inherited sheet silicates may survive if inherited sheet silicates are present they contribute to an increase in both the chemical heterogeneity and the apparent k ar ages of a sample

mercury intrusion and permeability of louiseville clay several theories have been proposed to correlate the permeability hydraulic conductivity with the pore size distribution of soils and it seemed interesting to determine if these theories could be applied to natural clays for this purpose permeability and mercury intrusion porosimetry tests were performed on a champlain sea clay for both intact and remoulded conditions after compression of the specimens to strains varying from 0 to 42 the results show that for either intact or remoulded soil conditions there is a relationship between the pore size parameters and the permeability of the clay however there is no unique relationship for both intact and remoulded clays and for the silt and clay considered in previous studies consequently mercury intrusion porosimetry alone cannot be usepto evaluate the permeability of soils in general plusieurs thkories ont ctc proposces pour corrcler la permiabilite conductivitk hydraulique avec la distribution des grosseurs de pore des sols et il a semblc intiressant de verifier si ces theories pourraient 2tre appliquees aux argiles naturelles a cette fin des essais de permcabilitc et de porosimctrie a intrusion de mercure okt ctc rcaliscs sur l argile de la mer champlain dans des conditions tant intactes que remanikes apris la compression des specimens a des dcformations variant de 0 a 42 les rcsultats demontrent que pour des conditions soit intactes ou remanices il existe une relation entre les paramitres de grosseur de pore et la permcabilitc de l argile cependant il n existe pas de relation unique pour les argiles tant intactes que remanices et pour le limon et l argile ctudics antkrieurement en conscquence la porosimctrie a intrusion de mercure ne peut pas a elle seule tre utilisce pour cvaluer la permcabilitc des sols en general mots clds permcabilitc argile porosimctrie a intrusion de mercure structure traduit par la rcdaction

probabilistic modelling of saturated unsaturated hydraulic conductivity for compacted glacial tills a probabilistic model including some previous probabilistic studies is proposed to evaluate hydraulic conductivity from pore entrance size distribution the model considers multi pores in series of paths through capillary networks in the soil fabric the average number of connected pores is a representative value of the fabric greater than two but not too large the hydraulic conductivity of three glacial tills from northern quebec with different grain size distributions has been examined by horizontal permeability tests in saturated conditions and suction tests with vertical permeability measurement in unsaturated conditions the hydraulic conductivity is strongly influenced by compaction conditions corresponding to different microfabrics the model is applicable not only in saturated conditions but also in unsaturated conditions with different microfabrics

olivine in terminal particles of stardust aerogel tracks and analogous grains in chondrite matrix abstract the dearth of both major and minor element analyses of anhydrous silicate phases in chondrite matrix has thus far hindered their comparison to the wild 2 samples we present 68 analyses of olivine fa 0 97 in the coarse grained terminal particles of stardust aerogel tracks and a comprehensive dataset 10 3 analyses of analogous olivine grains 5 30 m isolated in ci cm cr ch co cv3 oxidized cv3 reduced c3 ungrouped acfer 094 and ningqiang l ll 3 0 4 eh3 and kakangari chondrite matrix these compositions reveal that wild 2 likely accreted a diverse assortment of material that was radially transported from various carbonaceous and ordinary chondrite forming regions the wild 2 olivine includes amoeboid olivine aggregates aoas refractory forsterite type i and type ii chondrule fragments and or microchondrules and rare relict grain compositions in addition we have identified one terminal particle that has no known compositional analog in the meteorite record and may be a signature of low temperature aqueous processing in the kuiper belt the generally low cr content of feo rich olivine in the stardust samples indicates that they underwent mild thermal metamorphism akin to a petrologic grade of 3 05 3 15

chondrule fragments from comet wild2 evidence for high temperature processing in the outer solar system abstract terminal grains from c2063 1 154 1 0 track 154 and c2061 1 113 5 track 113 from the stardust collection of comet wild2 s coma have been studied by tem and nanosims terminal grain 2 of c2063 1 154 1 0 consists of an al rich diopside en 97 99 al 2 o 3 9 11 wt pigeonite en 85 wo 15 with tio 2 and al 2 o 3 contents of 0 5 and 5 2 wt and minor forsterite and enstatite the mineral assemblage and al rich ti poor composition of the grain are consistent with being a fragment of an al rich chondrule similar to those present in carbonaceous chondrites the oxygen isotopic composition of the c2063 1 154 1 0 grain was determined by nanosims analyses and found to be 17 o 10 6 5 7 18 o 7 5 2 5 and 17 o 1 4 4 3 18 o 6 5 1 6 1 errors for the two sections these figures are distinct from cais and consistent with an origin as al rich chondrule fragments terminal grain 5 of c2061 1 113 5 consists of low ca pyroxene en 86 87 fs 10 11 wo 3 4 and 2 wt al 2 o 3 and in one section 5 10 of a na rich silicate phase this assemblage may be a fragment of a low ca pyroxene bearing chondrule and mesostasis the original chondrule diameter for the c2063 1 154 1 0 and c2061 1 113 5 samples by analogy with carbonaceous chondrite chondrules might have been in the range 0 2 1 0 mm if they were of that size then the presence of large grains of high temperature material e g 1500 k for such refractory assemblages could be explained through commonly invoked models of radial drift from inner to outer solar system but only if the chondrules were first fragmented to dust within the inner solar system an alternative scenario is that some chondrule formation was associated with high temperature processing and planetesimals in the outer solar system

on the relationship between isolated and chondrule olivine grains in the carbonaceous chondrite alha77307 abstract the origin of isolated olivine grains in carbonaceous chondrites has been suggested to be either by direct condensation or by fragmentation of chondrules in an attempt to resolve this debate isolated olivine grains in the carbonaceous chondrite alha77307 have been studied in detail zoning characteristics and minor element compositions of olivines from all isolated and chondrule occurrences are described the data show that a strong relationship exists between isolated olivines and the chondrule population chondrule olivine compositions and zoning properties are consistent with olivine crystallization from the molten chondrules because properties of isolated grains are very similar to chondrule olivines an igneous origin for most if not all isolated grains is proposed large isolated forsterite grains may be derived from fragmentation of macroporphyritic type i chondrules which contain one or very few large olivine grains relic forsterite grains in type ii chondrules and complex isolated olivine grains with forsteritic cores and fayalite rich rims provide evidence that fragmentation and recycling of chondrules and their components was a common and efficient process in the chondrule forming region

rb sr and k ar dating of clay diagenesis in jurassic sandstone oil reservoir north sea rb sr and k ar isotopic determinations were combined with scanning electron microscopy sem observations and x ray diffractometry xrd controls to date the diagenetic formation of clay minerals from oil bearing sandstones of the middle jurassic brent sandstone in the north sea the separated clay fractions often contain detrital components especially k feldspars which are reduced to sizes smaller than 0 4 m either by intense in situ alteration or by destructive sample preparation direct rb sr and k ar isotopic dating of diagenetic illite therefore was not possible isotopic data obtained on mixtures of detrital and newly formed components showed however that illite formed about 40 to 45 ma this value also was obtained directly on clay fractions separated by a gentle method of disaggregation illitization is related to emplacement of hydrocarbons and associated waters into the formation aqueous and hydrocarbon fluids simultaneously trapped in quartz overgrowth inclusions indicate late silicification contemporaneous with this fluid migration minimum trapping temperatures of at least 110 c for these fluid inclusions are too high for the present burial depth hot fluids are assumed to have originated in deep source rocks beneath the brent reservoirs and migrated upward during the middle eocene

the paris meteorite the least altered cm chondrite so far the paris chondrite provides an excellent opportunity to study cm chondrules and refractory inclusions in a more pristine state than currently possible from other cms and to investigate the earliest stages of aqueous alteration captured within a single cm bulk composition it was found in the effects of a former colonial mining engineer and may have been an observed fall the texture mineralogy petrography magnetic properties and chemical and isotopic compositions are consistent with classification as a cm2 chondrite there are 45 vol high temperature components mainly type i chondrules with olivine mostly fa0 2 mean fa0 9 with granular textures because of low mesostasis abundances type ii chondrules contain olivine fa7 to fa76 these are dominantly of type iia but there are iiab and iib chondrules ii a b chondrules with minor highly ferroan olivine and iia c with augite as the only pyroxene the refractory inclusions in paris are amoeboid olivine aggregates aoas and fine grained spinel rich ca al rich inclusions cais the cai phases formed in the sequence hibonite perovskite grossite spinel gehlenite anorthite diopside fassaite and forsterite the most refractory phases are embedded in spinel which also occurs as massive nodules refractory metal nuggets are found in many cai and refractory platinum group element abundances pge decrease following the observed condensation sequences of their host phases mn cr isotope measurements of mineral separates from paris define a regression line with a slope of 53mn 55mn 5 76 0 76 106 if we interpret cr isotopic systematics as dating paris components particularly the chondrules the age is 4566 44 0 66 myr which is close to the age of cai and puts new constraints on the early evolution of the solar system eleven individual paris samples define an o isotope mixing line that passes through cm2 and co3 falls and indicates that paris is a very fresh sample with variation explained by local differences in the extent of alteration the anhydrous precursor to the cm2s was co3 like but the two groups differed in that the cms accreted a higher proportion of water paris has little matrix 47 plus 8 fine grained rims and is less altered than other cm chondrites chondrule silicates except mesostasis cai phases submicron forsterite and amorphous silicate in the matrix are all well preserved in the freshest domains and there is abundant metal preserved metal alteration stage 1 of palmer and lauretta 2011 metal and sulfide compositions and textures correspond to the least heated or equilibrated cm chondrites category a of kimura et al 2011 the composition of tochilinite cronstedtite intergrowths gives a pcp index of 2 9 cronstedtite is more abundant in the more altered zones whereas in normal highly altered cm chondrites with petrologic subtype 2 6 2 0 based on the s sio2 and feo sio2 ratios in pcp or tochilinite cronstedtite intergrowths rubin et al 2007 cronstedtite is destroyed by alteration the matrix in fresh zones has ci chondritic volatile element abundances but interactions between matrix and chondrules occurred during alteration modifying the volatile element abundances in the altered zones paris has higher trapped ne contents more primitive organic compounds and more primitive organic material than other cms there are gradational contacts between domains of different degree of alteration on the scale of 1 cm but also highly altered clasts suggesting mainly a water limited style of alteration with no significant metamorphic reheating

the mn fe negative correlation in olivines in alha 77257 ureilite mn fe and oxygen zoning profiles of olivines in the alha 77257 ureilite were measured by an electron probe microanalyzer to study the effects of reduction on the mn fe value because ureilite olivines exhibit thin reduced rims the mn content gradually increases toward the rim of ureilite olivines as the fa 100 fe mg fe mol component decreases which suggests that the mn fe content of olivine is related to redox conditions a calculated diffusional cooling rate of 1 2 c h gives the best fit to both the observed mno and fa chemical zoning profiles of alha 77257 the results of melting experiments suggest that the negative correlation of mn fe in olivine and low ca pyroxene is related to reduction and that the mn fe positive correlation is related to temperature the fe mn fe mg trend of olivine cores in ureilites may be established by the reduction process at about 1275 c

remarks on the design of clay liners used in lagoons as hydraulic barriers considering that i the hydraulic conductivity of compacted clays is smaller on the wet side of optimum ii the plastic limit is the water content below which the soil develops fissures under sm

quantified whole section trace element mapping of carbonaceous chondrites by synchrotron x ray fluorescence microscopy 1 cv meteorites abstract we present the application of a new synchrotron based technique for rapid mapping of trace element distributions across large areas of the cv3 meteorites allende and vigarano this technique utilizes the australian synchrotron x ray fluorescence microscopy xfm beam line with its custom designed and built x ray detector array called maia xfm with maia allows data to be collected using a 2 m spot size at very low dwell times 0 1 0 5 ms resulting in maps of entire thin sections in 5 h maia is an energy dispersive detector system with a large collection solid angle which allows full spectral acquisition and high sensitivity hence there is no need to constrain the elements of interest a priori we collected whole section maps 2 cm 1 cm from 3 thick sections of allende and a single map 2 cm 1 5 cm from a thick section of vigarano our experimental conditions provide data for elements with 20 z 40 k shell ca through zr and the l emissions of os ir pt au and pb we illustrate the unique capabilities of this technique by presenting observations across myriad length scales from the centimeter scale down to the detection of sub micrometer particles within these objects our initial results show the potential of this technique to help decipher spatial and textural variations in trace element chemistry between cais chondrules matrix and other chondritic components we also illustrate how these datasets can be applied to understanding both nebular and parent body processes within meteorites

geothermal studies in the san juan basin and the four corners area of the colorado plateau i terrestrial heat flow measurements abstract twenty five new heat flow measurements are presented for the san juan basin and the four corners area of the colorado plateau in the southwestern united states temperature gradients at most sites are calculated from temperature logs at depths between 1 km and 2 km resulting heat flow values appear to be locally less variable than shallower data these new data develop smooth uniform trends consistent with the regional geology as such it is reasonable to suggest that these data may be somewhat less influenced by near surface perturbations to heat flow than are shallower data in the area i e local hydrologie movement weathered conductivity samples topographic variations and paleoclimate effects heat flow increases going from the four corners area into the northern san juan basin a trend consistent with other geophysical studies heat flow also increases as the san juan basin is traversed south to north approaching the san juan volcanic field this observation suggests a unique thermal anomaly associated with the san juan volcanics heat flow in areas of the san juan basin quite away from extensive volcanics is 70 mw m 2 suggesting a small but statistically valid difference between regional heat flow in the non volcanic regions of the san juan basin and in some of the other non volcanic regions of the colorado plateau where the mean heat flow is 65 mw m 2 again this conclusion seems consistent with other geophysical data

fe mg fe mn relations of meteorites and primary heterogeneity of primitive achondrite parent bodies abstract we examine fe mg mn relations of meteorites as represented on plots of molar fe mg ratio vs molar fe mn ratio and use them to consider whether it is meaningful to classify achondrites as primitive or evolved first we demonstrate that fe mg fe mn plots can be used to identify some of the major processes that have affected meteorite parent bodies during both the nebular condensation and accretion and the planetary igneous stages of their evolution examination of compositions of chondrites on this diagram reveals distinct patterns that result from three nebular processes 1 volatility controlled mn mg fractionation 2 metal silicate fractionation under highly reducing conditions and 3 subsequent oxidation leading to variations in feo mgo ratio ordinary chondrites ocs show a characteristic pattern that records all three of these processes and suggests that the latter two are coupled examination of the compositions of achondrites on this diagram shows that all of those that have been classified as primitive lodranites acapulcoites winonaites iab silicate inclusions brachinites and ureilites are easily distinguished from those that have been classified as evolved sncs heds and lunar basalts the mn mg ratios of the former are chondritic while those of the latter are superchondritic hence they plot in two graphically distinct regions of the fe mg fe mn diagram a simple melting calculation reveals that this distinction results principally because the former are residues and the latter are melts or cumulate products of melts rather than because the latter are more evolved additionally however some of the groups classified as primitive achondrites show fe mg fe mn patterns similar to that of ocs constant but distinct mno mgo ratios over large ranges of feo mgo ratio we argue that these trends reflect primary heterogeneity resulting from the same nebular processes as those that affected ocs and therefore preserve evidence that more of the materials that accreted to form planetesimals experienced these processes than is apparent from known chondrites this evidence is preserved principally because these meteorites are residues in contrast groups commonly classified as evolved achondrites show fe mg fe mn patterns that reflect only igneous processing and any evidence for primary heterogeneity of their parent bodies has been obliterated again this is principally because these meteorites represent melts rather than beause they are more evolved usage of the terms primitive and evolved to describe achondrites should be clearly defined

architecture and evolution of an extensionally inverted thrust mt tancia thrust central apennines geological structural geochemical and k ar geochronological constraints abstract fault inversion may lead to significant obliteration of earlier tectonic structures thus preventing the straightforward interpretation of the complete kinematics and deformation history of faults we adopt a multidisciplinary approach to 1 reconstruct the tectonic evolution through space and in time of the extensionally inverted mt tancia thrust central apennines italy 2 understand the deformation mechanisms and the transition and reactivation of compressional structures during negative tectonic inversion and 3 constrain the origin of fluids involved during tectonic processes to this end we combined 1 detailed geological mapping and multiscale structural analysis 2 illite smectite paleothermal indicators 3 c o and clumped isotopes on calcite mineralizations and 4 k ar dating of authigenic and or syn kinematic illite from the mt tancia thrust fault rocks we show that shortening occurred between 9 and 7 ma during possibly multiple events of fluid overpressure and shear rupturing involving fluids entrapped over long term within the host rocks post compressive tectonic inversion occurred at 3 ma under fluid pressure fluctuations during shear events with an input of meteoric derived fluids tectonic inversion is spatially confined within the first few metres below the thrust surface in a volume dominated by the partial overprinting folding transposition and re utilization of the earlier compressional fabric

the age of illite cement growth village fields area southern north sea evidence from k ar ages and 18o 16o ratios in this paper we describe k ar radiometric ages and oxygen isotope ratio measurements of illite cements from eolian sandstone samples of the permian lower leman sandstone formation rotliegendes group the samples come from a large about 100 100 km part of the southern north sea basin village fields area and from a range of burial depths 2 8 3 4 km subsea bed mean illite ages in the gas fields of ravenspurn north 164 ma 20 1 2 sgr n 11 hyde 161 ma 12 3 n 7 cleeton 155ma 20 2 n 3 and hoton 152 ma 14 0 n 14 fields and in two wells located in block 47 5a 162 ma 16 1 n 4 are all in the middle to late jurassic apart from two early cretaceous ages considered to represent unreliable analyses the m an for all ages is 158 ma 18 6 2 sgr n 39 we largely avoided contamination with old detrital k bearing minerals by careful sample selection and monitoring to a first approximation the assumptions of k ar dating appear to be fulfilled so the measured ages are likely to date illite cement precipitation oxygen isotope ratios measured on the dated illite samples show small but significant variations among fields and a weak correlation with depth during the middle jurassic when illite grew both k ar dating and oxygen isotope ratios are compatible with a regional middle to late jurassic phase of illite growth during which the mineral precipitated over a large area and over a range of temperatures governed by the depth of the formation at that time the age of illite cementa ion coincides with rifting which ultimately may have caused illite growth by driving pore water flow

oxygen isotopes of chondritic components we review the oxygen isotopic compositions of chondrite components refractory inclusions chondrules and matrix and their inter and intra crystalline oxygen isotopic distributions primary oxygen isotopic compositions acquired before planetesimal accretion are easily disturbed by parent body processes such as aqueous alternation and thermal metamorphism primary or original oxygen isotopic compositions of refractory inclusions ca al rich inclusions and amoeboid olivine aggregates distribute along a slope 1 line on the three oxygen isotope diagram over the range of 60 17 o 18 o 16 o rich and 17 o 18 o rich during refractory inclusion formation on the other hand primary minerals of most chondrules have small isotopic variations and are enriched in 17 o and 18 o relative to refractory inclusions suggesting that chondrule formation occurred in 17 o 18 o rich nebular gas however rare 16 o rich chondrules have been found suggesting some overlap in the timing of formation of chondrules and refractory inclusions in the solar nebula oxygen isotopic compositions of matrix grains distribute along the slope 1 line over the same range as refractory inclusions and chondrules the similarity in oxygen isotopic distributions suggests that matrix was originally a mechanical mixture of nebular dusts co generated with chondrules and refractory inclusions presolar grains with oxygen isotopic compositions that are clearly distinct from those of solar nebular materials are a trace component of chondrite matrices based on these oxygen isotopic characteristics more than 99 5 of the solid materials in the nebula formed locally in the solar nebula and the remainder formed in interstellar space the astrophysical setting of chondrite component formation in the early solar system is also discussed refractory inclusions and 16 o rich matrix dusts formed around the inner edge of the solar nebula on the other hand most chondrules and 17 o 18 o rich matrix dusts seem to have formed elsewhere in the solar nebula efficient large scale radial mixing of the solar nebular materials may have been an essential process in the formation of chondritic planetesimals

the formation and alteration of the renazzo like carbonaceous chondrites ii linking o isotope composition and oxidation state of chondrule olivine abstract to better understand the formation conditions of type i and type ii chondrules in the renazzo like carbonaceous cr chondrites an in situ major and minor element and o isotope study was conducted twenty one ferromagnesian chondrules from three cr chondrites gra 95229 gra 06100 and que 99177 were analyzed to establish an internally consistent data set from this study we infer that type ii chondrule precursors contained enhanced s bearing dust and ice abundances relative to type i chondrules there is a relationship between the o isotope composition and oxidation state of olivine which may be related to the amount of 16 o poor ice and reduced carbon accreted by chondrule precursors before melting type ii chondrules formed under h 2 o h 2 ratios of 230 740 times solar in contrast type i chondrules formed under more reducing conditions with lower h 2 o h 2 ratios of 10 100 times solar we find a relationship between type ii chondrule petrology relict free vs relict grain bearing and o isotope composition which is due to degree of melting and exchange with a 16 o poor gas reservoir the 16 o poor gas that interacted with both type i and type ii chondrules is estimated to have an isotopic composition between 18 o g 13 27 and 17 o g 10 22 different from the o isotope composition of the water accreted by the cr chondrite parent body due to partial melting type i chondrules and relict grain bearing type ii chondrules exchanged with the 16 o poor gas to a lower degree than relict free type ii chondrules

identification of relict forsterite grains in forsterite rich chondrules from the mokoia cv3 carbonaceous chondrite magnesium rich forsterite grains fo 98 in feo poor chondrules show variations in cathodoluminescence cl intensity that are associated closely with variations in al 2 o 3 and tio 2 contents cl thus can be used to map the distribution of al and ti in individual grains we describe several categories of cl distribution including grains that are homogeneous grains that are zoned continuously grains that show oscillatory zoning and grains that show a heterogeneous distribution of cl intensity heterogeneous cl intensity is interpreted as the result of disequilibrium growth from the chondrule melt cl surveys of individual chondrules help to identify forsterite grains that are potentially relics in their host chondrules i e grains that did not crystallize in situ from the chondrule melt several of these grains show minor element variations that differ from the majority of melt grown grains in their host chondrules this observation supports the inference that they are relics little evidence exists for growth of individual grains in multiple brief heating episodes identification of the abundance of relict grains is important for determining the thermal histories of chondrules as well as the nature of the precursor assemblages from which they formed

probabilistic analysis of pore water pressures of an earth dam using a random finite element approach based on field data abstract knowledge of pore water pressure in an earth dam is crucial for analyzing its mechanical stability in classical calculations of these pressures great uncertainty exists regarding the permeability of the materials and the representation of their spatial variability in this article a probabilistic analysis of pore water pressures based on field data is performed to represent the permeability with a 2d random field established from statistical and geostatistical analyzes this random field is introduced in a model based on the finite element method fem and the influence of the spatial variability of permeability on pore water pressure is then studied using monte carlo simulations mcs

cordierite bearing lavas from jaguarao southern brazil petrological evidence for crustal melts during early rifting of gondwana abstract the jaguarao stratoid dacites rio grande do sul brazil are limited in areal extent are comprised of about 3 2 km3 of preserved erupted material and outcrop only in areas of the region underlain by mylonitic and ultramylonitic rocks they are s type volcanic rocks containing cordierite orthopyroxene plagioclase and ilmenite as liquidus phases and partially melted granite gneiss and migmatite enclaves that are very similar to the precambrian basement rocks the jaguarao lavas have distinct geochemical signatures and sr nd isotopes with respect to other volcanic rocks of the region available geochronological data for jaguarao dacites range between 157 5 ma and 139 6 7 4 ma considering the errors the younger ages obtained for jaguarao lavas overlap the 138 128 ma age of rocks of the serra geral group and thus indicate that the dacites were erupted prior to the break up of gondwana in this region petrographic mineralogical and petrochemical data as well as the tectonic context of the jaguarao lavas suggest that magma genesis was linked at least in part to friction melts the dacitic magma was generated by partial melting reactions involving biotite breakdown in a dominantly quartz feldspathic source terrane leaving a granulite facies residue in subsurface these melts were probably generated as a consequence of crustal thinning linked to simple shear extension just prior to gondwana break up and rifting of the southern atlantic ocean

thermochemical stability of low iron manganese enriched olivine in astrophysical environments low iron manganese enriched lime olivine grains are found in cometary samples returned by the stardust mission from comet 81p wild 2 similar grains are found in primitive meteoritic clasts and unequilibrated meteorite matrix lime olivine is thermodynamically stable in a vapor of solar composition at high temperature at total pressures of a millibar to a microbar but enrichment of solar composition vapor in a dust of chondritic composition causes the feo mno ratio of olivine to increase the compositions of lime olivines in primitive materials indicate oxygen fugacities close to those of a very reducing vapor of solar composition the compositional zoning of lime olivines in amoeboid olivine aggregates is consistent with equilibration with nebular vapor in the stability field of olivine without re equilibration at lower temperatures a similar history is likely for lime olivines found in comet samples and in interplanetary dust particles lime olivine is not likely to persist in nebular conditions in which silicate liquids are stable

k ar dating of time of gas emplacement in rotliegendes sandstone netherlands the time of emplacement of gas into each of two reservoirs in the rotliegendes sandstone one in the groningen field and one in the broad fourteens basin was estimated from potassium argon k ar ages of diagenetic illitic clays and careful petrographic observations of the rocks in which the clays occurred in each reservoir the intensity of diagenetic alteration increased downward within a relatively thin 15 to 175 m or 50 to 580 ft interval apparently reflecting a longer period of alteration for deeper samples this is expected in cases where a gradually accumulating gas column expels pore water from progressively deeper parts of the reservoir rock illite is a common diagenetic phase in the rotliegendes because detrital contamination in these rocks has been infer ed to be minimal k ar ages of very fine grained illite should indicate the time the illite forming process ceases in each case reported here the age of the deeper sample is younger than that of the shallower we interpret the age of the finest illite fraction in the gas zone of each reservoir to indicate the time at which illite formation ceased as the result of gas emplacement and pore fluid displacement in the rock our results indicate that gas emplacement in the groningen field commenced prior to 150 ma and that the growth of diagenetic illite continued in the present day water zone from that time until at least 120 ma

determination of planetary basalt parentage a simple technique using the electron microprobe many basaltic meteorites are being discovered in old and new meteorite suites including those from cold deserts e g antarctica and hot desert environments it is important to establish the specific planetary body source proven techniques for establishing planetary parentage include stable isotopic signatures especially oxygen certain elemental ratios in bulk samples and certain elemental ratios in specific minerals some of these techniques are expensive require considerable sample preparation and are adversely affected by weathering processes on the parent body or on earth we have been seeking key major and minor elemental ratios in pyroxene olivine and feldspar that can be measured by the electron microprobe on standard thin sections these ratios may be preserved in unweathered portions of mineral grains and thus see through weathering processes in addition if the sample is too small to provide a representative bulk composition it may still have key information recorded in individual minerals we have found that some of the most useful chemical parameters are fe mn atomic in olivine or pyroxene and the percent anorthite an in plagioclase solid solutions a plot of fe mn in pyroxene and or olivine verses an defines compositional fields that are significantly different for earth mars moon 4 vesta and the angrite parent body this method may be especially powerful when combined with oxygen isotope data

constraints on the formation environment of two chondrule like igneous particles from comet 81p wild 2 using chemical and petrologic evidence and modeling we deduce that two chondrule like particles named iris and callie from stardust cometary track c2052 12 74 formed in an environment very similar to that seen for type ii chondrules in meteorites iris was heated near liquidus equilibrated and cooled at 100 c hr and within 2 log units of the iw buffer with a high partial pressure of na such as would be present with dust enrichments of 103 there was no detectable metamorphic nebular or aqueous alteration in previous work ogliore et al 2012 reported that iris formed late 3 myr after cais assuming 26al was homogenously distributed and was rich in heavy oxygen iris may be similar to assemblages found only in interplanetary dust particles and stardust cometary samples called kool particles callie is chemically and isotopically very similar but not identical to iris

heat flow data and vertical groundwater movement examples from southwestern virginia in the present study we show that estimates of vertical specific discharge are often obtainable from plots of conducted heat flow q versus temperature t q t plots allow for variations in thermal conductivity across a zone of flow whereas temperature gradient g versus t plots assume constant conductivity it is demonstrated that the two different plots can provide quite different estimates of vertical specific discharge by considering vertically convected heat flow across a zone better estimates of regional geologically representative heat flow can be made agreement between corrected heat flow values conducted heat flows calculated near fluid flow exit boundaries and regional values suggests that the steady state flow model used is reasonably representative although the fluid flow depth interval is typically difficult to estimate confidently the effects of small continuous well bore flow can be removed if continuity in the temperature log results otherwise it is most difficult to estimate specific discharge as confirmed by unrepresentative corrected heat flow data

the origin age and duration of hydrothermal alteration associated with iron skarn mineralization determined from clay phyllosilicate minerals bizmisen erzincan east central turkey abstract the bizmisen skarn type iron deposit is one of the major operating mines in east central turkey middle eocene 46 3 42 0 ma plutonic rocks quartz diorite were intruded into triassic cretaceous limestones and upper cretaceous ophiolites forming skarns garnet diopside epidote scapolite and tremolite iron mineralization and clay bearing alteration zones argillic alteration clay rich rocks of the argillic zone contain mainly quartz calcite dolomite feldspar and clay phyllosilicate minerals comprising dioctahedral smectite kaolinite mixed layered illite smectite i s and illite and trioctahedral vermiculite serpentine chrysotile talc chlorite and mixed layered chlorite smectite c s na ca smectite i s illite and kaolinite are developed at both the quartz diorite limestone contact and within the quartz diorite body however phlogopite vermiculite serpentine chrysotile talc and chlorite occur at the quartz diorite ophiolite contacts indicating the distributions of clay phyllosilicate minerals are influenced primarily by the host rock composition chlorite geothermometry data suggest 300 c for the retrograde stage of skarn formation and 120 c for the late argillic alteration overprint and the formation of low temperature clays smectite vermiculite c s in areas of skarn formation kaolinite 1 m one layer monoclinic and i s i75 s25 r1 ordering are indicative of low temperature

k ar dating of fault gouge in the northern sydney basin nsw australia implications for the breakup of gondwana abstract the occurrence of synkinematic and authigenic clay minerals is a common feature in fault gouges few attempts have been made to date fault gouges we present the first age data in australia for synkinematic illite smectite growth in two fault zones of the northern sydney basin nsw the faults occur at burwood beach nsw in the northern part of the sydney basin and are hosted by early permian siltstones tuffs and coals of the lambton formation newcastle coal measures the faults are 1 5 m apart show normal displacement and trend n s with steep easterly dips foliated gouge zones comminution and dilational breccias are developed along both fault surfaces k ar ages extracted from samples in the gouge and tuffs in the damage zones are 172 6 10 m to 119 ma 2 m 237 245 ma for the

the abundance and relative volatility of refractory trace elements in allende ca al rich inclusions implications for chemical and physical processes in the solar nebula abstract we have determined the relative volatility of lithophile refractory trace elements lrte in the solar nebula by first calculating 50 condensation temperatures for 26 lrte oxides assuming ideal solid solution in perovskite and where appropriate in hibonite and melilite the measured abundances of 25 lrte and six siderophile refractory trace elements in 97 group i 11 111 and v allende ca al rich inclusions cai s and in ultra refractory inclusions then are used to empirically modify lrte and refractory siderophile volatility sequences that are based on condensation temperatures alone sc is significantly less depleted in group ii allende cai s than are other lrte e g zr hf y that also have very high oxide condensation temperatures ba sr and eu three moderately volatile lrte are significantly more enriched in ca rich group ii and group iii allende cai s than they are in spinel rich varieties of these inclusions we explain these observations and several others by invoking dust fractionation s and crystal chemical and diffusion effects during the formation of allende cai s that overprinted volatility based on solid gas reactions alone for example we show that hibonite probably was not the carrier of the super refractory lithophile component that is missing from group ii allende inclusions anomalous hf depletions relative to zr and y that are common in group i iii and v allende cai s can be partly explained if anders and ebihara 38 overestimated the cosmic abundance of hf by approximately 10

terminal particle from stardust track 130 probable al rich chondrule fragment from comet wild 2 abstract a 4 6 m terminal particle from stardust track 130 named bidi is composed of a refractory assemblage of fo 97 olivine al and ti bearing clinopyroxene and anorthite feldspar an 97 mineralogically bidi resembles a number of components found in primitive chondritic meteorites including al rich chondrules plagioclase bearing type i ferromagnesian chondrules and amoeboid olivine aggregates aoas measured widths of augite pigeonite lamellae in the clinopyroxene indicate fast cooling rates suggesting that bidi is more likely to be a chondrule fragment than an aoa bulk element concentrations including an al 2 o 3 content of 10 2 wt further suggests that bidi is more akin to al rich rather than ferromagnesian chondrules this is supported by high anorthite content of the plagioclase feldspar overall bulk composition and petrogenetic analysis using a cosmochemical al 2 o 3 ca 2 sio 4 mg 2 sio 4 phase diagram measured minor element abundances of individual minerals in bidi generally support an al rich chondrule origin but are not definitive between any of the object types oxygen isotope ratios obtained from olivine minor high ca pyroxene fall between the tf and ccam lines and overlap similar minerals from chondrules in primitive chondrites but are generally distinct from pristine aoa minerals oxygen isotope ratios are similar to some minerals from both al rich and type i ferromagnesian chondrules in unequilibrated carbonaceous enstatite and ordinary chondrites although no single piece of evidence uniquely identifies bidi as a particular object type the preponderance of data including mineral assemblage bulk composition mineral chemistry inferred cooling rates and oxygen isotope ratios suggest that bidi is more closely matched to al rich chondrules than aoas or plagioclase bearing type i ferromagnesian chondrules and likely originated in a chondrule forming region in the inner solar system

vadose zone fluid flow estimates calculated from temperature measurements taken in the southern albuquerque basin at tome new mexico 1 closely spaced temperature measurements taken across the vadose zone at tome new mexico suggest upward and or horizontal fluid flow between 58 and 30 m depth the temperature depth profile is an independent data set that in the present example is best fitted by the exponential expression characterizing vertically upward water flow in addition expressions representing horizontal flow and combined horizontal and vertical flow also provide relatively good fits to the temperature data a unique hydrogeologic environment is present at the tome site where a thick clay layer straddles the water table at 59 m depth neutron and bulk density porosity logs indicate the clay porosity is largely liquid phase water filled it is suggested that matrix potential and perhaps osmosis are able to drive an uncommonly large vertical fluid flow for southwestern u s desert vadose zone sites because the presence of the saturated clay layer straddling the relatively shallow water table provides ideal conditions the vertical specific discharge estimate is 0 09 m yr 1 liquid water horizontal flow may also be possible in the clay layer and is estimated as 23 m yr 1 both the vertical and horizontal flow estimates are not untypical for the saturated zone in the albuquerque basin

petrology and origin of amoeboid olivine aggregates in cr chondrites amoeboid olivine aggregates aoas are irregularly shaped fine grained aggregates of olivine and ca al rich minerals and are important primitive components of cr chondrites the aoas in cr chondrites contain feni metal and some aoas contain mn rich forsterite with up to 0 7 mno and mn fe ratios greater than one additionally aoas in the cr chondrites do not contain secondary phases nepheline and fayalitic olivine that are found in aoas in some cv chondrites the aoas in cr chondrites record a complex petrogenetic history that included nebular gas solid condensation reaction of minerals with the nebular gas small degrees of melting and sintering of the assemblage a condensation origin for the mn rich forsterite is proposed the mn rich forsterite found in idps unequilibrated ordinary chondrite matrix and aoas in cr chondrites may have had a similar origin a type a calcium aluminum rich inclusion cai with an aoa attached to its wark lovering rim is also described this discovery reveals a temporal relationship between aoas and type a inclusions additionally a thin layer of forsterite is present as part of the wark lovering rim revealing the crystallization of olivine at the end stages of the wark lovering rim formation the ca al rich nodules in the aoas may be petrogenetically related to the ca al rich minerals in wark lovering rims on type a cais aoas are chondrite components that condensed during the final stage of wark lovering rim formation but in general were temporally spatially or kinetically isolated from reacting with the nebula vapor during condensation of the lower temperature minerals that were commonly present as chondrule precursors

hydraulic conductivity of compacted tills from northern quebec the hydraulic conductivity of six compacted tills from northern quebec with different grain size distributions has been studied in saturated conditions in the laboratory the results show that comp

oxygen isotopes in crystalline silicates of comet wild 2 a comparison of oxygen isotope systematics between wild 2 particles and chondritic materials abstract oxygen three isotope ratios of nine crystalline silicate particles from comet wild 2 were measured to investigate oxygen isotope systematics of cometary materials we are able to analyze particles as small as 4 m using an ion microprobe with a 1 2 m beam by locating the analysis spots with an accuracy of 0 4 m three particles of mn rich forsterite known as low iron manganese enriched lime olivine showed extremely 16 o rich signatures 18 o 17 o 50 similar to refractory inclusions in chondrites the three mn rich forsterite particles may have formed by condensation from an 16 o rich solar nebula gas other particles consist of olivine and or pyroxene with a wide range of mg molar mgo feo mgo from 60 to 96 their oxygen isotope ratios plot nearly along the carbonaceous chondrite anhydrous mineral ccam and young and russell lines with 17 o 17 o 0 52 18 o values of 3 0 to 2 5 these data are similar to the range observed from previous analyses of wild 2 crystalline silicates and those of chondrules in carbonaceous chondrites six particles extracted from stardust track 77 show diverse chemical compositions and isotope ratios two mn rich forsterites feo poor pigeonite and three feo rich olivines with a wide range of 17 o values from 24 to 1 6 these results confirmed that the original projectile that formed track 77 was an aggregate 6 m of silicate particles that formed in various environments the 17 o values of ferromagnesian wild 2 particles including data from previous studies increase from 23 to 2 5 with decreasing mg 17 o values of mn rich forsterite particles mg 98 99 8 cluster at 23 those of feo poor particles mg 95 97 cluster at 2 and those of feo rich particles mg 90 scatter mainly from 1 5 to 2 5 compared to chondrules in primitive chondrites the systematic trend between mg and 17 o among the wild 2 particles is most similar to that reported for cr chondrite chondrules we argue that cr chondrites and some cometary materials share multiple common chemical and isotope characteristics we suggest that many of the crystalline silicate particles formed in the outer regions of the asteroid belt or regions that share the common properties and were transported to comet forming regions and accreted into comet wild 2

the influence of soil structure and stress history on the soil water characteristics of a compacted till the soil water characteristic defines the relationship between the soil suction and gravimetric water content w or the volumetric water content or the degree of saturation s theoretical and

estimates of terrestrial heat flow from deep petroleum tests along the rio grande rift in central and southern new mexico twenty six new estimates of heat flow are calculated for the albuquerque belen basin and the basins of the southern rio grande rift in new mexico from these and previous data the following heat flow patterns may be suggested the regional or background heat flow in the albuquerque belen basin is 77 mw m 2 there is also a ne sw trend of higher heat flow 92 110 mw m 2 across the region in the southern rio grande rift between socorro and las cruces the regional heat flow appears to be 95 mw m 2 in this region there are also higher heat flows 117 135 mw m 2 at widely scattered sites south of las cruces near the international border between mexico and the united states preliminary and perhaps suspect data suggest the possibility of a transition to the intermediate heat flows previously estimated at sites throughout much of northeastern chihuahua mexico regional heat flow values in the albuquerque belen basin and in the basins of the southern rio grande rift are consistent with but do not constrain simple models of crustal thinning higher heat flows in these two areas are thought to be caused by hydrothermal fluids largely groundwaters but possibly magma in some areas transporting heat upward along crustal fracture zones

refractory materials in comet samples transmission electron microscope examination of more than 250 fragments 1 m from comet wild 2 and a giant cluster interplanetary dust particle gcp of probable cometary origin has revealed four new calcium aluminum rich inclusions cais an amoeboid olivine aggregate aoa and an additional aoa or al rich chondrule arc object all of the cais have concentric mineral structures and are composed of spinel anorthite cores surrounded by al ti clinopyroxenes and are similar to two previous cais discovered in wild 2 all of the cometary refractory objects are of moderate refractory character the mineral assemblages textures and bulk compositions of the comet cais are similar to nodules in fine grained spinel rich inclusions fgis found in primitive chondrites and like the nodules may be nebular condensates that were altered via solid gas reactions in the solar nebula oxygen isotopes collected on one wild 2 cai also match fgis the lack of the most refractory inclusions in the comet samples may reflect the higher abundances of small moderately refractory cai nodules that were produced in the nebula and the small sample sizes collected in the comet samples approximately 2 3 of all fragments larger than 1 m by number are cais and nearly 50 of all bulbous stardust tracks contain at least one cai we estimate that 0 5 volume of wild 2 material and 1 volume of gcp is in the form of cais arcs and aoas account for 1 of the wild 2 and gcp grains by number

matrix and fine grained rims in the unequilibrated co3 chondrite alha77307 origins and evidence for diverse primitive nebular dust components abstract the mineralogical and chemical characteristics of dark matrix and fine grained rims in the unequilibrated co3 chondrite alha77307 have been investigated in detail by scanning electron microscopy electron microprobe analysis and transmission electron microscopy matrix and fine grained rims on chondrules and other objects are compositionally homogeneous on the scale of 10 m and there are no compositional differences between matrix and rims mineralogically both the matrix and rims are extremely diverse and consist of a highly unequilibrated assemblage of si and fe rich amorphous material olivine pyroxene fe ni metal magnetite pentlandite pyrrhotite anhydrite and mixed layer phyllosilicate phases several distinct components can be recognized within the matrix and rims based on their textural and compositional characteristics which appear to represent basic fine grained units of nebular dust the microstructures of these different components show that they have experienced significantly different thermal histories unlike the ordinary chondrites an origin for any significant component of the matrix or rims in alha77307 from chondrules is improbable based on compositional and microstructural evidence the matrix and rim components in alha77307 formed by disequilibrium condensation processes as fine grained amorphous dust that is represented by the abundant amorphous component in the matrix such condensation could have occurred under a variety of conditions at different times and locations within the solar nebula or possibly earlier in a circumstellar environment subsequent thermal processing of this primitive condensate material in a variety of environments in the nebula resulted in partial or complete recrystallization of the fine grained dust the intimate association of fine grained components with disparate compositions and thermal histories shows that mixing of fine grained dust within the nebula must have been extremely thorough

origin of crystalline silicates from comet 81p wild 2 combined study on their oxygen isotopes and mineral chemistry in order to explore the link between comet 81p wild 2 and materials in primitive meteorites seven particles 5 to 15 m in diameter from comet 81p wild 2 have been analyzed for their oxygen isotope ratios using a secondary ion mass spectrometer most particles are single minerals consisting of olivine or pyroxene with mg higher than 85 which are relatively minor in 81p wild 2 particles 1 3 of the 16o poor cluster four particles extracted from track 149 are 16o poor and show 17o 17o 0 52 18o values from 2 0 to 1 0 similar to previous studies while one enstatite en99 particle shows lower 17o value of 7 4 o 2 this compositional range has not been reported among 16o poor particles in 81p wild 2 but is commonly observed among chondrules in carbonaceous chondrites and in particular in cr chondrites the distribution in 17o indicates that 16o poor 81p wild 2 particles are most similar to chondrules and their fragments in the cr chondrites and tagish lake like wis91600 chondrite chondrule silicate grains which indicates that they likely come from a reservoir with similar dust ice ratios as cr chondrites and wis91600 however differences in the mg distribution imply that the 81p wild 2 reservoir was comparatively more oxidized with a higher dust enrichment two nearly pure enstatite grains from track 172 are significantly enriched in 16o with 18o values of 51 2 1 5 0 2 and 43 0 1 3 2 respectively and 17o values of 22 3 1 9 2 and 21 3 2 3 0 2 respectively they are the first 16o rich pyroxenes found among 81p wild 2 particles with similar 17o values to those of 16o rich low iron manganese enriched lime olivine and cai calcium and aluminum rich inclusions like particles from 81p wild 2 the major element and oxygen isotopic compositions of the pyroxenes are similar to those of enstatite in amoeboid olivine aggregates aoas in primitive chondrites in which 16o rich pyroxenes have previously been found and thus suggest a condensation origin

influence of compaction conditions on pore size distribution and saturated hydraulic conductivity of a glacial till the paper examines the hydraulic conductivity of a nonplastic till from northern quebec it is shown that the hydraulic conductivity is strongly influenced by the compaction degree of saturation and the variation of hydraulic conductivity with void ratio is influenced by compaction conditions determination of pore size distributions and microphotographs provide evidence that changes in hydraulic conductivity are related to the fabric of the compacted specimens and macroporosity developing when the soil is compacted at degrees of saturation less than that at the optimum key words till hydraulic conductivity microfabric

using precision temperature logs to estimate horizontal and vertical groundwater flow components a new method of estimating the horizontal and vertical specific discharge components of groundwater flow from precision subsurface temperature measurements is presented plotting the vertical temperature gradient as a function of both z and t and then fitting a plane to the data can provide coefficients from which the vertical and horizontal groundwater specific discharge components may be estimated alternatively by considering the vertical component of groundwater to be zero it is shown that quadric or cubic fits to temperature data provide coefficients from which horizontal groundwater flow may be estimated these expressions along with expressions previously derived to estimate only vertical only horizontal or both vertical and horizontal flow components are fitted to observational data from four sites and five flow zones it is learned for these examples using an available fitting program that although many of the expressions fit the observational data very well statistically those expressions which incorporate both the vertical and horizontal flow components of specific discharge must generally be constrained so that resulting parameters will provide flow estimates consistent in direction and heat transfer with available piezometer data and or the fundamental curvature of the temperature log expressions incorporating only x or only z can sometimes yield estimates quite different from the estimates obtained from the expressions incorporating both x and z it is concluded that an estimate of the horizontal and vertical flow components requires both consideration of the flow calculations along with available piezometric data and the fundamental curvature of the temperature log

influence of groundwater flow on the estimation of subsurface thermal parameters we investigated the influence of groundwater flow on the thermal tests performed in borehole heat exchangers to infer the underground thermal properties temperature time signals were simulated with a moving line source mls model under different hypotheses of darcy velocity periodic and random noise was included in the synthetic data obtained with this model in order to mimic high frequency disturbances caused by several possible sources e g equipment instability and changes in environmental conditions during the experiment that often occur in real signals the subsurface thermal conductivity the darcy velocity and the borehole thermal resistance were inferred by minimising the root mean square error between the synthetic dataset and the model the calculated thermal and hydraulic parameters were consistent with the a priori values the optimisation procedure results were then tested with the infinite line source ils model for a darcy velocity exceeding 10 7 m s 1 ils largely overestimates thermal conductivity the approach relying on the mls model was finally tested with real temperature time data and produced reliable estimates of thermal conductivity darcy velocity and borehole thermal resistance the inferred groundwater flow was cross checked by means of an independent method based on the analysis of temperature depth logs recorded under thermal equilibrium conditions such a test validates the darcy velocity inferred with the mls approach

variations in the o isotope composition of gas during the formation of chondrules from the cr chondrites to better understand the environment of chondrule formation and constrain the o isotope composition of the ambient gas in the renazzo like carbonaceous cr chondrite chondrule forming region we studied the mineralogy petrology and in situ o isotope compositions of olivine in 11 barred olivine bo chondrules and pyroxene and silica in three type i porphyritic chondrules from the cr chondrites gao guenie b graves nunataks gra 95229 pecora escarpment pca 91082 and shisr 033 bo chondrules experienced a higher degree of melting than porphyritic chondrules and therefore it has been hypothesized that they more accurately recorded the o isotope composition of the gas in chondrule forming regions we studied the o isotope composition of silica as it has been hypothesized to have formed via direct condensation from the gas bo chondrules constitute 4 of the total cr chondrule population by volume on a three isotope oxygen diagram 17o vs 18o olivine phenocrysts in type i and type ii bo chondrules plot along slope 1 line with the exception of a type ii bo chondrule that plots along slope 0 5 line olivine phenocrysts in type i and type ii bo chondrules have similar but more restricted ranges of 17o values 3 8 to 1 3 and 0 8 to 1 4 respectively than those in type i and type ii porphyritic chondrules 4 6 to 0 3 and 1 8 to 0 9 respectively the observation that olivine grains in type i bo chondrules have similar chemical and o isotope compositions to those of olivine in their porphyritic counterparts argues against the hypothesis that olivine grains in type i porphyritic chondrules are xenocrysts and represent relict fragments of early formed planetesimals the compositional and o isotope data suggest that bo chondrules experienced more extensive but incomplete exchange with the ambient gas than porphyritic chondrules we suggest that cr chondrules formed from relatively 16o enriched solids in the presence of relatively 16o depleted gaseous h2o the o isotope compositions of chondrule olivine likely result from differences in the o isotope composition of both the chondrule precursors and the ambient gas during chondrule formation the inferred o isotope composition of this gas 17o ranges from 3 to 3 is inconsistent with a high abundance of water from the outer solar system which has been predicted to be isotopically heavy

high temperature condensation of iron rich olivine in the solar nebula abstract olivine is the most abundant mineral in many chondritic meteorites it is also the first major mg silicate to condense from a solar gas upon cooling the composition of olivine provides important information concerning its origin results of calculations are presented for the fe mn and ni contents of olivine condensing from a gas with solar composition but variable oxygen fugacity a basic computational method is described that takes into account the depletion of the gas in mg and si during condensation the first olivine that condenses from a solar gas has less than 10 2 mol feo independent of the oxygen fugacity of the otherwise solar gas at lower temperatures when most of the mg is condensed more feo can be incorporated in forsterite by condensation if the oxygen fugacity is sufficiently high the feo mno ratio of the first condensing olivine is above 1000 decreasing with decreasing temperature and increasing oxygen fugacity to values of around 100 which are actually observed in fayalitic olivine rims in allende the ni content of condensed olivine is below 10 7 mol even at high oxygen fugacities indicating that condensation of nio in olivine is a very unlikely process any ni in olivine in the ppm range is therefore indicative of metal olivine equilibration under increasingly oxidizing conditions h 2 o h 2 ratios of 0 01 0 1 chromite is an early phase to condense forming before forsterite isolated olivine grains in allende and olivine on the outside of chondrules have feo rich rims texture composition and morphology of these rims indicate that they formed by condensation from a gas our calculations suggest that the gas was enriched by a factor of 100 in oxygen relative to solar composition gas and that mg was almost completely condensed when rim formation occurred the sharp boundary between forsteritic and fayalitic olivine suggests an increase in oxygen fugacity and rapid formation of fayalitic olivine by condensation cr enrichment at the rim interface with the underlying forsterite probably reflects stability of chromite under oxidizing conditions conventional models of feo bearing silicate formation require oxidation of metal silicate assemblages at temperatures as low as 400 k it is shown here that diffusion at this temperature is so slow that the time needed for formation of the observed feo bearing phases would exceed the lifetime of the solar nebula other oxygen fugacity indicators reflect similar conditions for example the hercynite component of spinel in fine grained al rich inclusions indicates equilibration with a gas of similar composition as that responsible for condensation of fayalitic olivine suggesting formation of feo rich spinel by gas solid reactions mechanisms for producing oxidizing conditions in the solar nebula are briefly discussed

the meteoritical bulletin no 83 1999 july meteoritical bulletin no 83 lists information for 898 newly described meteorites these include 473 from antarctica 341 from the sahara and 22 from dry lakes in the southwestern united states seven of the meteorites are falls kunya urgench h5 lohawat howardite ourique h4 portales valley h6 san pedro de quiles l6 talampaya eucrite and zag h3 6 also included are a dozen new iron meteorites several mesosiderites a pallasite several hed meteorites several ureilites a variety of cm co cv cr and r chondrites and numerous unequilibrated ordinary chondrites all shock classifications are after stoffler et al 1991 and weathering grades are after wlotzka 1993 except as noted all italicized abbreviations refer to addresses tabulated at the end of this document

age constraints on faulting and fault reactivation a multi chronological approach movement within the earth s upper crust is commonly accommodated by faults or shear zones ranging in scale from micro displacements to regional tectonic lineaments since faults are active on different time scales and can be repeatedly reactivated their displacement chronology is difficult to reconstruct this study represents a multi geochronological approach to unravel the evolution of an intracontinental fault zone locality along the danube fault central europe at the investigated fault locality ancient motion has produced a cataclastic deformation zone in which the cataclastic material was subjected to hydrothermal alteration and k feldspar was almost completely replaced by illite and other phyllosilicates five different geochronological techniques zircon pb evaporation k ar and rb sr illite apatite fission track and fluorite u th he have been applied to explore the temporal fault activity the upper time limit for initiation of faulting is constrained by the crystallization age of the primary rock type known as kristallgranit at 325 7 ma whereas the k ar and rb sr ages of two illite fractions 2 m 266 255 ma are interpreted to date fluid infiltration events during the final stage of the cataclastic deformation period during this time the kristallgranit was already at or near the earth s surface as indicated by the sedimentary record and thermal modelling results of apatite fission track data u th he thermochronology of two single fluorite grains from a fluorite quartz vein within the fault zone yield cretaceous ages that clearly postdate their late variscan mineralization age we propose that later reactivation of the fault caused loss of helium in the fluorites this assertion is supported by geological evidence i e offsets of jurassic and cretaceous sediments along the fault and apatite fission track thermal modelling results are consistent with the prevalence of elevated temperatures 50 80 c in the fault zone during the cretaceous

the formation and alteration of the renazzo like carbonaceous chondrites iii toward understanding the genesis of ferromagnesian chondrules to better understand the formation conditions of ferromagnesian chondrules from the renazzo like carbonaceous cr chondrites a systematic study of 210 chondrules from 15 cr chondrites was conducted the texture and composition of silicate and opaque minerals from each observed feo rich type ii chondrule and a representative number of feo poor type i chondrules were studied to build a substantial and self consistent data set the average abundances and standard deviations of cr2o3 in feo rich olivine phenocrysts are consistent with previous work that the cr chondrites are among the least thermally altered samples from the early solar system type ii chondrules from the cr chondrites formed under highly variable conditions e g precursor composition redox conditions cooling rate with each chondrule recording a distinct igneous history the opaque minerals within type ii chondrules are consistent with formation during chondrule melting and cooling starting as s and ni rich liquids at 988 1350 c then cooling to form monosulfide solid solution mss that crystallized around olivine pyroxene phenocrysts during cooling fe ni metal crystallized from the s and ni rich liquid and upon further cooling mss decomposed into pentlandite and pyrrhotite with pentlandite exsolving from mss at 400 600 c the composition texture and inferred formation temperature of pentlandite within chondrules studied here is inconsistent with formation via aqueous alteration however some opaque minerals fe ni metal versus magnetite and panethite present in type ii chondrules are a proxy for the degree of whole rock aqueous alteration the texture and composition of sulfide bearing opaque minerals in graves nunataks 06100 and grosvenor mountains 03116 suggest that they are the most thermally altered cr chondrites

analysis of the annual thermal response of an earth dam for the assessment of the hydraulic conductivity of its compacted till core heat carried by the seepage water along hydraulic flow lines can serve as a natural tracer to help detect contrasting hydraulic conductivities in embankment dams thermal monitoring was realized on the 94 5 m high qa 01 embankment dam in northern quebec to characterize the temperature distribution across its entire section the analysis of the annual thermal response of the dam clearly showed a zone of higher seepage velocities in the compacted till core approximations concerning the increased hydraulic conductivity were made using a simple thermal model complementary numerical modelling provided a more rigorous quantitative assessment of the seepage patterns the calculations have shown hydraulic conductivities that are 20 times larger than the expected values thermal monitoring can detect zones of increased seepage which can be related to internal erosion or other factors such as the variability of the soil properties due to construction practices temperature measurements alone are not adequate to

calcium aluminum rich inclusions and amoeboid olivine aggregates from the cr carbonaceous chondrites calcium aluminum rich refractory inclusions cais in cr chondrites are rare 1 vol fairly small 500 m and irregularly shaped and most of them are fragmented based on the mineralogy and petrography they can be divided into grossite hibonite rich melilite rich and pyroxene anorthite rich cais other types of refractory objects include fine grained spinel melilite pyroxene aggregates and amoeboid olivine aggregates aoas some of the pyroxene anorthite rich cais have igneous textures and most melilite rich cais share similarities to both the fluffy and compact type a cais found in cv chondrites one major difference between these cais and those in cv cm and co chondrites is that secondary mineral phases are rare in situ ion microprobe analyses of oxygen isotopic compositions of 27 cais and aoas from seven cr chondrites demonstrate that most of the cais are 16o rich 17o of hibonite melilite spinel pyroxene and anorthite 22 and isotopically homogeneous within 3 4 likewise forsterite spinel anorthite and pyroxene in aoas have nearly identical 16o rich compositions 24 17o 20 deg in contrast objects which show petrographic evidence for extensive melting are not as 16o rich 17o less than 18 o secondary alteration minerals replacing 16o rich melilite in melilite rich cais plot along the terrestrial fractionation line most cr cais and aoas are mineralogically pristine objects that largely escaped thermal metamorphism and secondary alteration processes which is reflected in their relatively homogeneous 16o rich compositions it is likely that these objects or their precursors condensed in an 16o rich gaseous reservoir in the solar nebula in contrast several igneous cais are not very enriched in 16o probably as a result of their having melted in the presence of a relatively 16o poor nebular gas if the precursors of these cais were as 16o rich as other cr cais this implies either temporal excursions in the isotopic composition of the gas in the cai forming regions and or radial transport of some cai precursors into an 16o poor gas the absence of oxygen isotope heterogeneity in the primary minerals of melilite rich cais containing alteration products suggests that mineralogical alteration in cr chondrites did not affect oxygen isotopic compositions of their cais

assessing hydraulic conductivities of a compacted dam core using geostatistical analysis of construction control data the surveillance of a 94 5 m high embankment dam in northern quebec canada revealed the possibility of the existence of a zone of higher hydraulic conductivity in its till core the spatial continuity of the measured fines content in the dam during construction was computed by geostatistical means to predict values at unsampled locations for the entire core volume the hydraulic conductivities were inferred using the predicted fines content and in situ compaction conditions the inferred hydraulic conductivities and their spatial representations were supported by thermal and seepage field monitoring data this provided the necessary background information to interpret the surveillance data and determine the cause of the presence of a more pervious zone in the core which was related to spatial variability of the fines content of the till placement water content and compaction procedures the geostatistical approach complemented with laboratory and construction control data is an efficient tool to char

compositional evolution of the protoplanetary disk oxygen isotopes of type ii chondrules from cr2 chondrites chondrules are the dominant component of chondritic meteorites and attest to high temperature transient heating events within the protoplanetary disk they provide valuable constraint on the disk environments in which they formed and potentially the evolution of primitive planetary materials in the disk the oxygen isotopic composition of cr2 chondrite type ii chondrules was investigated our data show significant variation in the isotopic compositions of the chondrules with no petrographic or geochemical means to identify what chondrule will plot where on a three isotope diagram although we cannot rule out that these chondrules may have come from another chondrite forming region we argue in context of type i chondrules from cr2 chondrites that cr2 type ii chondrules record changes in solid and gas composition during formation due to the vaporization of icy bodies in localized regions of the inner disk

possible ambiguities in subsurface temperature logs consideration of ground water flow and ground surface temperature change subsurface temperature regimes can commonly be influenced by both ground water flow in the saturated zone and ground surface temperature change both phenomena are widespread and one or the other may be unnoticed and or unanticipated in various temperature logs as a consequence it is often difficult to determine the relative impact of the two phenomena on the temperature depth data at a site a number of models for ground water flow ground surface temperature change and a combination of the two processes are fitted to two example temperature logs showing characteristic nonlinearity examples of the possible impact of one phenomenon on the parameters calculated for the other phenomenon demonstrate the potential interactive influence the analysis can be used to estimate potential uncertainties in calculations of ground water flow and ground surface temperature change from subsurface temperature data and therefore how interpretations of ground water flow and ground surface warming might be affected from the analysis presented the relative importance of the two phenomena may be further considered at different locations

nebular history of amoeboid olivine aggregates minor element ca cr and mn concentrations in amoeboid olivine aggregates aoas from primitive chondrites were measured and compared with those predicted by equilibrium condensation in the solar nebula cao concentrations in forsterite are low particularly in porous aggregates a plausible explanation appears that an equilibrium ca activity was not maintained during the olivine condensation cao and mno in forsterite are negatively correlated with cao being higher in compact aggregates this suggests that the compact aggregates formed either by a prolonged reheating of the porous aggregates or by condensation and aggregation of forsterite during a very slow cooling in the nebula

inferring hydro geothermal parameters from advectively perturbed thermal logs we present techniques to infer thermo hydraulic parameters from the analysis of underground temperature data from boreholes two different cases are analyzed thermal data from artesian wells and from boreholes drilled in unconfined aquifers the former allow the assessment of the formation temperature gradient and the flow volume the latter give estimates of the darcy velocity and consequently allow the inference of the aquifer hydraulic conductivity the analysis procedure consists in matching thermal logs with analytical models incorporating both heat and mass transfer the thermo hydraulic parameters are obtained from the coefficients of the advective models by means of the least square fitting method examples of applications are given for a set of temperature logs from a geothermal area of northwestern italy preliminarily thermal gradients and the correction for the recent climate change were evaluated from thermal data of boreholes with no evidence of advection the analysis of artesian boreholes gave high formation thermal gradients in agreement with those obtained from boreholes with dominant conductive thermal regime in boreholes drilled in permeable formations the models predicting the temperature versus depth distribution resulted generally less sensitive to geological noise and fitted the field data better than the models based on the gradient analysis if the shape of the thermal profile is taken into account as a qualitative descriptor of the type of flow reliable estimates of the flow components can be obtained

heat flow data suggest large ground water fluxes through fruitland coals of the northern san juan basin colorado new mexico temperature logs and heat flow data from wells in the northern san juan basin colorado new mexico suggest that coals of the fruitland formation are an aquifer with appreciable horizontal ground water movement calculated hydraulic conductivities based on ground water flow rates estimated from heat flow data are several orders of magnitude greater than hydraulic conductivities measured in laboratory or pumping tests fractures and other preferential pathways probably create high regional hydraulic conductivity that allows significant heat advection

diversity of the initial rocky planetary building materials at the edge of the solar system asteroids and comets are surviving members of the vast planetesimal population that was distributed across the early solar system they appear to be a diverse set of bodies but we present evidence from comet samples that the body to body diversity of the initial rocky component mix in planetesimals may have declined with distance from the sun laboratory measurements of the minor element mn in olivine collected from comet wild 2 suggests that the micron sized rocky crystalline contents of this comet formed in numerous inner solar system environments the results are consistent with a scenario where silicates such as olivine form at incandescent temperatures in multiple environments and then mix as they are transported to distant cold regions where silicates could accrete with ice and organics to form comets accreting far from silicate formation regions many ice rich planetesimals are likely to have started with similar complex mixtures of diverse rocky components formed in various high temperature environments this contrasts with asteroidal meteorite parent bodies whose silicates retain regional properties that give different chondrite classes their distinctive properties

petrology and mineralogy of type ii feo rich chondrules in semarkona ll3 0 origin by closed system fractional crystallization with evidence for supercooling abstract the petrology of type ii porphyritic olivine chondrules in semarkona ll3 0 has been studied in detail olivines in these chondrules are euhedral fe richand are strongly zoned from cores to rims of grains in feo fa10 30 cr2o3 0 2 0 6 wt mno 0 2 0 7 wt and cao 0 1 0 4 wt interstitial mesostasis is rich in si aland ca and is glassy with abundant microcrystallites minor minerals include troilite fe ni metaland chromite some olivine grains contain euhedral fayalite rich cores that are probably produced during initial supercooling of the chondrule melt rare relict grains of forsteritic olivine have compositions very similar to olivines in type ia chondrules in semarkona and may result from disaggregation of such chondrules apart from these relics all properties of type ii chondrules can be described by closed system fractional crystallization of droplets which were essentially entirely molten the chondrules did not originate as aggregates of large olivine grains and are unlikely to be fragments of precursor igneous rocks cooling rates of the order of 1000 c h are indicated from peak temperatures of around 1600 c the chondrules show considerable evidence for supercooling and large departures from equilibrium during crystallization there is no evidence for chondrule nebula exchange either during or after crystallization or any secondary processes such as aqueous alteration or thermal metamorphism bulk composition data suggest that precursor material included a refractory ca al ti rich component similar to one of the precursor components of type ia chondrulesand a non refractory fe and si rich component type ia chondrules may have formed from type ii chondrules by loss of fe and volatiles alternatively the two chondrule types may have formed in regions of considerable diversity in the solar nebula from precursor materials with different fe mg ratios

lime silicates in amoeboid olivine aggregates in carbonaceous chondrites indicator of nebular and asteroidal processes mno feo ratios in olivine from amoeboid olivine aggregates aoas reflect conditions of nebular condensation and can be used in concert with matrix textures to compare metamorphic conditions in carbonaceous chondrites lime low iron mn enriched olivine was identified in aoas from y 81020 co3 05 kaba cv 3 1 and in y 86009 cv3 y 86751 cv3 nwa 1152 cr cv3 but was not identified in aoas from efremovka cv3 1 3 4 or allende cv 3 6 according to thermodynamic models of nebular condensation lime olivine is stable at lower temperatures than mn poor olivine and at low oxygen fugacities dust enrichment 95 in our study whereas efremovka aoas are slightly fe rich fo 92 aoa olivines from kaba are mostly forsteritic but rare fe rich olivine precipitated from an aqueous fluid a combination of precipitation of fe rich olivine and diffusion of fe into primary olivine grains resulted in iron rich compositions fo97 59 in allende aoas variations from fine grained nonporous matrix toward higher porosity and coarser lath like matrix olivine can be divided into six stages represented by 1 y 81020 efremovka nwa 1152 2 y 86751 lithology b 3 y 86009 4 kaba 5 y 86751 lithology a 6 allende these stages are inferred to represent general degree of metamorphism although the specific roles of thermally driven grain growth and diffusion versus aqueous dissolution and precipitation remain uncertain

dating fault gouges geological faults are fractures in the earth s crust along which there has been some displacement and are thus zones of weakness which are of importance in planning civil engineering projects constructing underground caverns and conducting earthquake research to assess the potential for future displacements and fluid circulation along faults it is helpful to establish the age of the latest episode of mineral growth in fault zones however there have been few attempts to date recrystallized and newly grown minerals developed in fault zones at low temperature1 4 here we report k ar and rb sr ages for clay fractions from two fault zones in the eastern alps and compare them with ages of the same fine fractions from the undeformed host rock the results suggest that the bulk of the clays along these faults were formed during early cretaceous and tertiary times respectively no major displacements seem to have taken place in recent times

late paleozoic mesozoic tectonic evolution of the trans altai and south gobi zones in southern mongolia based on structural and geochronological data abstract the trans altai zone in southern mongolia is characterized by thrusting of greenschist facies silurian oceanic rocks over devonian and lower carboniferous volcano sedimentary sequences by e w directed folding affecting the early carboniferous volcanic rocks and by the development of n s trending magmatic fabrics in the devonian carboniferous arc plutons this structural pattern is interpreted as the result of early carboniferous thick skinned e w directed nappe stacking of oceanic crust associated with syn compressional emplacement of a magmatic arc the southernmost south gobi zone represents a proterozoic continental domain affected by shallow crustal greenschist facies detachments of ordovician and devonian cover sequences from the proterozoic substratum whereas supracrustal carboniferous volcanic rocks and permian sediments were folded into n s upright folds this structural pattern implies e w directed thin skinned tectonics operating from the late carboniferous to the permian as demonstrated by k ar ages ranging from 320 ma to 257 ma for clay fractions separated from a variety of rock types moreover the geographical distribution of granitoids combined with their geochemistry and shrimp u pb zircon ages form distinct groups of carboniferous and permian age that record typical processes of magma generation and increase in crustal thickness the field observations combined with clay ages the geochemical characteristics of the granitoids and their ages imply that the e w trending zone affected by tectonism migrated southwards leaving the trans altai zone inactive during the late carboniferous and permian suggesting that the two units were tectonically amalgamated along a major e w trending strike slip fault zone this event was related to late carboniferous subduction that was responsible for the vast volume of granitoid magma emplaced at 300 305 ma in the south gobi and at 307 308 ma in the trans altai zones the formation and growth of the crust was initially due only to subduction and accretion processes during the post collisional period from 305 to 290 ma the addition of heat to the crust led to the generation of per alkaline melts once amalgamated these two different crustal domains were affected by n s compression during the triassic and early jurassic 185 173 ma resulting in e w refolding of early thrusts and folds and major shortening of both tectonic zones

40ar 39ar muscovite dating of thrust activity a case study from the axial zone of the pyrenees abstract the pyrenees belt features well exposed deformation structures that make it ideally suited to study thrust faults in this paper we present the first 40ar 39ar age of the pic de port vieux thrust ppvt located in the south western part of the pyrenean axial zone the ppvt is a secondary thrust related to the major gavarnie thrust gt with a footwall comprising upper cretaceous limestones and a hanging wall made of lower triassic pelites and sandstones a vertical transect in the fault hanging wall was investigated to characterize the deformation mechanism and to date the thrust activity by using 40ar 39ar step heating technique on muscovite petrographic observations confirm that pressure solution and recrystallization dissolution processes in presence of fluids are the main mechanisms that controlled the chemical textural changes in the fault core zone three groups of muscovite are identified in the fault zone i e detrital diagenetic and newly formed muscovites the detrital and diagenetic muscovites are mainly present in the damage zone while the newly formed muscovite is abundant in the core zone and is synkinematic to the fault activity the fractions 50 16 m 16 2 m 2 0 5 m

oxygen isotope ratios of feo poor chondrules in cr3 chondrites influence of dust enrichment and h2o during chondrule formation abstract we present detailed electron microprobe analyses and oxygen three isotope measurements by high precision secondary ion mass spectrometry on 45 type i feo poor chondrules fragments and 3 type ii feo rich chondrule fragments from meteorite hills 00426 and queen alexandra range 99177 two of the most primitive cr3 chondrites type i chondrules fragments have mg s defined as the mg of constituent olivine and or low ca pyroxene ranging from 94 2 to 99 2 type ii chondrule fragments have mg s of 53 63 oxygen three isotope measurements plot on the slope 1 primitive chondrule mineral pcm line within chondrules 17 o 17 o 0 52 18 o values of coexisting olivine pyroxene and plagioclase are homogeneous with propagated uncertainties of 0 3 this indicates each phase crystallized from the final chondrule melt and that efficient oxygen isotope exchange occurred between ambient gas and chondrule melt among type i chondrules there is a well defined increase in 17 o from 5 9 to 1 as mg s decrease from 99 2 to 96 type ii chondrule fragments are comparatively 16 o poor 17 o 0 2 0 6 the relationship between mg and 17 o among type i chondrules confirms that addition of a 16 o poor oxidizing agent to the highest mg chondrule precursors resulted in forming lower mg cr chondrules using aspects of existing equilibrium condensation models and a mass balance we estimate that type i cr chondrules formed at dust enrichments of 100 200 from dusts with 0 0 8 times the atomic abundance of ice relative to ci dust the type ii chondrule fragments are predicted to have formed at ci dust enrichments near 2500

groundwater flow analysis using different geothermal constraints the case study of acqui terme area northwestern italy abstract we review some analytical techniques that use underground thermal data as tracers of groundwater flow these techniques allow the evaluation of the darcy velocity in shallow aquifers of mid low permeability and the evaluation of heat gain loss by conduction in deeper aquifers examples of application are then given for the acqui terme hydrothermal system located in the tertiary piedmont basin northwestern italy the analysis of borehole temperatures allowed the inference of the hydraulic features of the sedimentary cover of the hydrothermal system the results show the presence of a relatively weak flow with upward and horizontal components only in conglomerates occurring at the base of the marly impermeable cover the analysis of the heat transported in the deep parts of the hydrothermal system was approached by splitting the water path into different sections each with given shape slope and hydraulic properties the recharge area is situated in the upland south of the discharge area meteoric water initially descends and then flows horizontally within the fractured metamorphic basement of the basin heating by conduction finally from a reservoir positioned at intermediate depths hot water reaches rapidly the surface through a sub vertical fault this scheme of deep water flow is constrained by the regional surface heat flow and the local geothermal gradient and it is consistent with data of rock water equilibrium temperature

timing of brittle deformation within the nojima fault zone japan abstract k ar ages from clay fault gouges of outcrop and core samples ug500 well from the nojima fault zone awaji island japan are consistent internally with established field constraints and with apatite and zircon fission track ages demonstrating the suitability of this method for dating of brittle deformation six unspiked and thirty conventional k ar data of clay minerals separated from gouge zones were analysed characterized by protoliths of high grade metamorphic and magmatic rocks the samples from the nojima fault zone offer the opportunity to distinct identify newly grown illite in the fault planes all dated sample fractions were characterized by xrd sem and tem k ar ages of 29 separates have an age range from 63 4 1 3 ma early palaeocene danian to 42 2 1 0 palaeogene middle eocene lutetian some

palaeomagnetic evidence for the age of the cumbrian and manx hematite ore deposits implications for the origin of hematite mineralization at the margins of the east irish sea basin uk examples of epigenetic hematite mineralization located at the margins of the east irish sea basin have been sampled for palaeomagnetic investigation to establish the timing of ore formation samples collected from 10 sites in cumbria are dominated by hematite of near pure composition and characterized by dual polarity and in part dual component magnetizations that yield palaeopoles nine sites between 50 n 130 e and 50 n 150 e in contrast samples recovered from seven sites on the isle of man have more varied mineralogical compositions that include ferromagnets with lower unblocking temperatures manx hematite mineralization also exhibits dual polarity but magnetizations yield steeper inclinations with palaeopoles lying between 55 n 130 e and 70 n 150 e steeper directions probably reflect minor tilting of the manx block following hematite emplacement correlation of poles with the european apparent polar wander path indicates that these ore deposits formed during the middle triassic results show that hematite mineralization sited at the margins of the east irish sea basin is essentially contemporaneous and establishes for the first time an underlying temporal relationship between these geographically dispersed ore bodies dating places the mineralization within a broader extensional geotectonic regime associated with the early rifting of pangaea in the north atlantic the context implies a causal link between crustal extension development of ore forming fluids within the evolving east irish sea basin and subsequent migration of fluids to basin margins where iron was precipitated as hematite supplementary materials locations and details of palaeomagnetic sample sites and a tabulation of selected reference palaeomagnetic poles defining the triassic and early jurassic segment of the apparent polar wander path for the european sector of the eurasian plate are available at www geolsoc org uk sup18691

microporosity structure of coarse granular soils to date the microporosity structures of coarse soils with various coarse fines contents are still not fully understood in this study the pore size distributions psds of five types of soil varying from gravel to clay were characterized using mercury intrusion porosimetry the soil with a coarse content below 70 i e fines content above 30 is found to have a fines controlled microstructure which is sensitive to water content changes such soil forms a dual porosity structure due to compaction in which both intraaggregate pores and interaggregate pores are dominant after saturation the dual porosity structure evolves into a unimodal porosity structure dominated by the intraaggregate pores during drying such soil exhibits a significant reduction of total volume the soil with a coarse content above 70 instead has a coarse controlled microstructure which is stable upon water content changes such soil maintains dual porosity structures no matter if the soil is compacted saturated or dried as an example of application the measured psds are used to predict the soil water characteristic curves swccs for the test soils and the predictions are consistent with the swccs measured in the laboratory

cretaceous reactivation of the deokpori thrust taebaeksan basin south korea constrained by k ar dating of clayey fault gouge 1 the deokpori thrust juxtaposing the early paleozoic yeongwol type joseon supergroup yeongwol group against the duwibong type joseon supergroup taebaek group in the okcheon belt is an important regional structure in the phanerozoic tectonic evolution of korea although the initiation of the thrust has recently been conjectured to occur during the middle jurassic daebo tectonic event in a continental magmatic arc setting its movement history has never been studied we report timing of brittle reactivation of the thrust obtained from k ar dating of fault gouges in the core of the deokpori thrust zone k ar illite age data of fault gouges suggest reactivation of the thrust at ca 72 ma after a contact metamorphism around 94 ma our result is the first documentation of the reactivation of a major jurassic daebo structure and the reactivation may represent a significant contractional tectonic event during the late cretaceous in the korean peninsula

fe mn systematics of type iia chondrules in unequilibrated co cr and ordinary chondrites we have examined fe mn systematics of 34 type iia chondrules in eight highly unequilibrated co cr and ordinary chondrites using new data from this study and prior studies from our laboratory olivine grains from type iia chondrules in co chondrites and unequilibrated ordinary chondrites uoc have significantly different fe mn ratios with mean molar fe mn 99 and 44 respectively olivine analyses from both these chondrite groups show well defined trends in mn versus fe afu and molar fe mn versus fe mg diagrams in general type iia chondrules in cr chondrites have properties intermediate between those in uoc and co chondrites in most uoc and cr type iia chondrules the fe mn ratio of olivine decreases during crystallization whereas in co chondrites the fe mn ratio does not appear to change it is difficult to interpret the observed fe mn trends in terms of differing moderately volatile element depletions inherited from precursor materials instead we suggest that significant differences in the abundances of silicates and sulfides metals in the precursor material as well as open system behavior during chondrule formation were responsible for establishing the different fe mn trends using fe mn mg systematics we are able to identify relict grains in type iia chondrules which could be derived from previous generations of chondrules including chondrules from other chondrite groups and possibly chondritic reservoirs that have not been sampled previously