early diagenesis in deep sea turbidites the imprint of paleo oxidation zones sediment cores up to 35 m long have been recovered from turbidite sequences in the madiera abyssal plain and the southern nares abyssal plain detailed geochemical analyses of these sediments si al fe mn ca organic and inorganic carbon and associate pore waters nitrate ammonia silicate fe2 mn2 and alkalinity provide representative profiles of both steady state and nonsteady state diagenetic reactions initiated by oxidation and reduction processes models demonstrate that chemical transport in the pore water system is diffusion dominated over periods of a few thousands of years to several hundreds of thousands of years mn and fe mobilized in the subsurface mildly reducing sediments are precipitated as easily reducible oxyhydroxides in the near surface oxidized sediments nonsteady state profiles show the influence of episodic and rapid turbidite deposition and the imprint of oxidation zones that developed as the result of oxygen diffusion into the upper portions of turbidites during intervals of slow pelagic deposition the time required for development of oxidation zones between turbidites ranges from 2 0 to 15 ka in the madeira abyssal plain and from 0 2 to 2 4 ka in the southern nares abyssal plain paleo oxidation zones can be recognized in old turbidites by distinct changes in color between lower and upper portions of the deposit in the basal unoxidized portion of the turbidite the sediments are characteristically dark green gray or brown in the paleo oxidized zone the sediments are pale green blue or yellowish brown these zones in both the madeira and southern nares abyssal plains contain distinctly less organic c and carbonate in the paleo oxidized zone as compared with the unoxidized sediments depletion of carbonate content in the oxidized zones in the southern nares abyssal plain is particularly significant in that as much as 80 of the initial carbonates have been lost also the relative amounts of weak acid soluble fe and mn are generally less in the paleo oxidized zones due to the initial oxidation of metal carbonate and metal hydroxide forms to easily reducible oxide forms which are then subsequently solubilized under the mildly reducing conditions at depth in the sediment column

the effects of water use on tothian flow systems in the mexico city conurbation determined from the geochemical and isotopic characteristics of groundwater groundwater flow systems have been differentiated in the metropolitan zone of mexico city based on their chemical composition and stable isotope contents the existing hydrogeological framework for the region provided a reference for such differentiation local flows flow system i represent the youngest and shallowest groundwater flow identified in boreholes on the hills intermediate flows flow system ii in boreholes on the plain represent a mixture of inflows travelling horizontally and vertically upwards flow system iv and downwards overlaying aquitard leakage to extraction boreholes flow system iii identified in boreholes on the plain is an intermediate flow system which extends deeper than flow system ii flow system iv which is classified as a regional system is related to a former thermal spring site groundwater travelling times and their regional distribution and the thickness of related rock formations suggest extensive inflow supporting flow system iv future climate condition evolution i e drought will only have a limited impact on flow system iv as compared to flow system i which have relatively rapid and short flow paths the identification of the hierarchy of the flow systems is of paramount importance in achieving adequate groundwater management in any region where the aquifer units are several thousand metres thick

aragonite breunnerite calcite and dolomite in the cm carbonaceous chondrites high fidelity recorders of progressive parent body aqueous alteration abstract carbonate minerals in cm carbonaceous chondrite meteorites along with the silicates and sulphides with which they are intergrown provide a detailed record of the nature and evolution of parent body porosity and permeability and the chemical composition temperature and longevity of aqueous solutions fourteen meteorites were studied that range in petrologic subtype from mildly aqueously altered cm2 5 to completely hydrated cm2 0 all of them contain calcite whereas aragonite occurs only in the cm2 5 cm2 2 meteorites and dolomite in the cm2 2 cm2 0 all of the aragonite crystals and most of the calcite and dolomite grains formed during early stages of parent body aqueous alteration by cementation of pores produced by the melting of tens of micrometre size particles of h2o rich ice aragonite was the first carbonate to precipitate in the cm2 5 to cm2 2 meteorites and grew from magnesium rich solutions in the least altered of these meteorites the aragonite crystals formed in clusters owing to physical restriction of aqueous fluids within the low permeability matrix the strong correlation between the petrologic subtype of a meteorite the abundance of its aragonite crystals and the proportion of them that have preserved crystal faces is because aragonite was dissolved in the more altered meteorites on account of their higher permeability and or greater longevity of the aqueous solutions dolomite and breunnerite formed instead of aragonite in some of the cm2 1 and cm2 2 meteorites owing to higher parent body temperatures the pore spaces that remained after precipitation of aragonite dolomite and breunnerite cements were occluded by calcite following completion of cementation the carbonates were partially replaced by phyllosilicates and sulphides calcite in the cm2 5 cm2 2 meteorites was replaced by fe rich serpentine and tochilinite followed by mg rich serpentine in the cm2 1 and cm2 0 meteorites dolomite breunnerite and calcite were replaced by fe rich serpentine and fe ni sulphide again followed by mg rich serpentine the difference between meteorites in the mineralogy of their replacive sulphides may again reflect greater temperatures in the parent body regions from where the more highly altered cms were derived this transition from fe rich to mg rich carbonate replacement products mirrors the chemical evolution of parent body solutions in response to consumption of fe rich primary minerals followed by the more resistant mg rich anhydrous silicates almost all of the cms examined contain a second generation of calcite that formed after the sulphides and phyllosilicates and by replacement of remaining anhydrous silicates and dolomite dedolomitization the ca and co2 required for this replacive calcite is likely to have been sourced by dissolution of earlier formed carbonates and ions may have been transported over metre plus distances through high permeability conduits that were created by impact fracturing

the classification of micrometeorites due to their small size the mineralogical and chemical properties of micrometeorites mms are not representative of their parent bodies on the centimeter to meter scales that are used to define parent body groups through the petrological study of meteorites identifying which groups of mm are derived from the same type of parent body is problematic and requires particles to be rigorously grouped on the basis of mineralogical textural and chemical properties that reflect the fundamental genetic differences between meteorite parent bodies albeit with minimal bias towards preconceived genetic models specifically the interpretation of mms requires a rigorous and meaningful classification scheme at present the classification of mms is however at best ambiguous a unified petrological chemical classification scheme is proposed in the current study and is based on observations of several thousand mms collected from antarctic ice

geochemical evolution of groundwater beneath mexico city abstract the geochemical evolution of groundwaters along a 24 km flow beneath central mexico city path from the sierra de las cruces towards lake texcoco has been investigated using stable isotopes radiocarbon and major and trace elements to determine the natural baseline conditions the extent of any contamination and the effectiveness of the overlying aquitard seal modern groundwaters of low salinity 1 are found up to 11 km from the outcrop area and groundwater ages of up to 6000 yr bp occur in the middle part of the section groundwater stable isotope ratios 18 o and 2 h lie close to the global meteoric water line indicating that the groundwater originates from local rainfall the groundwater chemistry may be interpreted as the result of inputs from the source area with progressive water rock interaction down the horizontal flow gradient a redox boundary is found at 9 km along the line of section coincident with the start of the confined section relatively low nitrate concentrations below 9 mg l 1 no 3 n are found in the aerobic waters low concentrations of no 3 in the aerobic waters and low cl reflect inputs prior to the modern development some elements cr u as se sb increase their concentration with distance time as far as the redox boundary but low concentrations occur in the reducing aquifer section the chemistry of several major ions mg na cl k as well as trace elements such as li rb ba reflect the weathering of the basaltic mineral assemblage feldspars and mafic minerals and their increases are generally proportional to residence time phosphate f and i concentrations indicate a probable source from apatite in the basaltic or rhyolitic rocks a borehole in the east of the city some 17 km downgradient intercepted thermal water si geothermometry indicates 163 c at depth this water gives a distinctive composition indicating possible addition of metamorphic co 2 which has then reacted with the igneous rocks increases in b and cl are derived from volatiles trapped in the glass or vesicular basalt a thermal anomaly found in the middle section of the heavily pumped aquifer is interpreted as the up coming of warmer water from medium to greater depth mainly from basalts rhyolites and possibly limestones the geochemistry indicates that groundwater beneath mexico city is of good quality and there is no obvious evidence of leakage of inorganic compounds from surface sources of contamination through the aquitard the younger groundwater drawn from the western outcrop area is generally of good inorganic quality increased drawdowns in the confined aquifer have induced flow of warmer water with higher cl from depth the resources in the aquifer represent an important reserve of good quality water which need to be properly managed as a high quality resource as part of integrated plans for the city s future supplies

widespread oxidized and hydrated amorphous silicates in cr chondrites matrices implications for alteration conditions and h2 degassing of asteroids abstract the cr chondrites carry one of the most pristine records of the solar nebula materials that accreted to form planetesimals they have experienced very variable degrees of aqueous alteration ranging from incipient alteration in their matrices to the complete hydration of all of their components in order to constrain their chemical alteration pathways and the conditions of alteration we have investigated the mineralogy and fe oxidation state of silicates in the matrices of 8 cr chondrites from type 3 to type 1 fe l edge x ray absorption near edge structure xanes was performed on matrix fib sections using synchrotron based scanning transmission x ray microscopy stxm the fe 3 fe ratio of submicron silicate particles was obtained and coordinated with tem observations in all the least altered cr chondrites que 99177 eet 87770 eet 92042 lap 02342 gra 95229 and renazzo we find that the matrices consist of abundant submicron fe rich hydrated amorphous silicate grains mixed with nanometer sized phyllosilicates the fe 3 fe ratios of both amorphous and nanocrystalline regions are very high with values ranging from 68 to 78 in the most altered samples al rais and gro 95577 fine grained phyllosilicates also have a high fe 3 fe ratio around 70 whereas the coarse micrometer sized phyllosilicates are less oxidized down to 55 and have a lower iron content these observations suggest the following sequence submicron fe2 amorphous silicate particles were the building blocks of cr matrices after accretion they were quickly hydrated and oxidized leading to a metastable amorphous gel like phase nucleation and growth of crystalline phyllosilicates was kinetically limited in most type 3 and 2 crs but increased as alteration became more extensive in al rais and gro 95577 the decreasing fe 3 fe ratio is interpreted as a result of the transfer of fe3 from silicates to oxides during growth while aqueous alteration progressed higher temperature longer duration change of fluid composition in a fully closed system equilibrium thermodynamics suggest that the water to rock ratios typically assumed to be low fe 3 fe ratio such a high fe 3 fe value could be accounted for however if the system was partially open at least with respect to h2 and other gases as well rapid degassing of the fluid would have favored more oxidizing fluid conditions recently proposed scenarios involving some degree of water d h increase through rayleigh isotopic fractionation are supported by these results

origin of chondrule rims and interchondrule matrices in unequilibrated ordinary chondrites optical microscopy electron probe microanalysis scanning electron microscopy and analytical transmission electron microscopy were used to study the interchondrule matrix and opaque chondrule rims in bishunpur krymka semarkona chainpur all ll3 tieschitz and sharps both h3 the size distribution of grains in matrix in bishunpur obeys a power law rims around chondrules tend to be finer grained than matrix and may be layered all rims and matrices studied contain clasts of forsteritic olivine and low ca pyroxene in bishunpur the clasts may be cemented by amorphous glue rich in normative albite and partly altered to smectite rims in krymka sharps chainpur and tieschitz have a densely packed olivine groundmass with a grain size of about 0 1 m in krymka groundmass olivine is fo20 30 and forms interlocking dendrites various fe oxides are present in rims and matrices grain size distribution and chemical data indicate that clastic olivines and pyroxenes are derived from chondrules from analyses matrices rims in the ll group apparently are enriched in a feldspathic component tieschitz rims are slightly enriched but here the feldspathic component is present as white matrix sharps rims are not enriched in a feldspathic component opaque interchondrule matrices and chondrule rims probably formed from the products of fragmentation of chondrules partly induced by contraction of protopyroxene on inversion to clinopyroxene fragmented silica rich chondrule mesostases reacted with fe oxides and na to form the groundmass of fayalitic olivine and feldspathic glue a low temperature nebular or pre solar component is limited to 3 vol of each meteorite so equilibrium condensate was not the carrier of volatiles such as tl and bi

the oxygen isotope record in murchison and other carbonaceous chondrites the ranges of 18o and 17o in components of the murchison c2 chondrite exceed those in all other meteorites analyzed previous authors have proposed that c2 chondrites are the products of aqueous alteration of anhydrous silicates a model is presented to determine whether the isotopic variations can be understood in terms of such alteration processes the minimum number two of initial isotopic reservoirs is assumed two major stages of reservoir interaction are required one at high temperature to produce the16o mixing line observed for the anhydrous minerals and another at low temperature to produce the matrix minerals the isotopic compositions severely constrain the conditions of the low temperature process requiring temperatures 44 extension of the model to the data on c1 chondrites requires aqueous alteration in a warmer wetter environment

density porosity and magnetic susceptibility of carbonaceous chondrites abstract we report physical properties bulk and grain density magnetic susceptibility and porosity measured using nondestructive and noncontaminating methods for 195 stones from 63 carbonaceous chondrites grain densities over the whole population average 3 44 g cm 3 ranging from 2 42 g cm 3 ci1 orgueil to 5 66 g cm 3 cb bencubbin magnetic susceptibilities in log units of 10 9 m3 kg 1 averaged log 4 22 ranging from 3 23 cv3 axtell to 5 79 cb bencubbin porosities averaged 17 ranging from 0 for a number of meteorites to 41 for one stone of the co ornans notably we found significant differences in porosity between the oxidized and reduced cv subgroups with the porosities of cvo averaging approximately 20 and cvr porosities approximately 4 overall porosities of carbonaceous chondrite falls trend with petrographic type from type 1 ci near 35 type 2 cm cr averaging 23 type 3 cv co 21 to type 4 ck and some co averaging 15 there is also a significant decrease in porosity between meteorites of shock stage s1 and those of s2 indicative of shock compression

temperatures of aqueous alteration and evidence for methane generation on the parent bodies of the cm chondrites aqueous alteration of primitive meteorites was among the earliest geological processes during the evolution of our solar system clumped isotope thermometry of carbonates in the cm chondrites cold bokkeveld murray and murchison demonstrates that they underwent aqueous alteration at 20 71 c from a fluid with 18 o vsmow of 2 0 to 8 1 and 17 o vsmow of 0 1 to 3 0 the 13 c vpdb values of these carbonates exhibit a negative correlation with the 18 o vsmow of their formation waters consistent with formation and escape of 13 c depleted ch 4 during aqueous alteration methane generation under these conditions implies that the alteration fluid was characterized by an eh 0 67 and ph 12 5 or lower at the highest alteration temperatures our findings suggest that methane generation may have been a widespread consequence of planetesimal and planetary aqueous alteration perhaps explaining the occurrence of methane on titan triton pluto and other kuiper belt objects

accretion rate of cosmic spherules measured at the south pole micrometeorites are terrestrially collected extraterrestrial particles smaller than about 1 mm which account for most of the mass being accreted to the earth1 2 compared with meteorites micrometeorites more completely represent the earth crossing meteoroid complex3 4 and should include fragments of asteroids comets mars and our moon as well as pre solar and interstellar grains3 6 previous measurements of the flux of micrometeoroids that survive to the earth s surface have large uncertainties owing to the destruction of particles by weathering7 8 9 inefficiencies in magnetic collection or separation techniques7 8 9 low particle counts10 11 poor age constraint7 8 9 12 13 or highly variable concentrating processes12 13 here we describe an attempt to circumvent these problems through the collection of thousands of well preserved and dated micrometeorites from the bottom of the south pole water well which supplies drinking water for the scott amundsen station using this collection we have determined precise estimates of the flux and mass distribution for 50 700 m cosmic spherules melted micrometeorites allowing for the expected abundance of unmelted micrometeorites14 in the samples our results indicate that about 90 of the incoming mass of submillimetre particles evaporates during atmospheric entry our data indicate the loss of glass rich and small stony spherules from deep sea deposits7 8 and they provide constraints for models describing the survival probability of micrometeoroids15 16

integration of seismic methods with reservoir simulation pikes peak heavy oil field saskatchewan reservoir characterization is essential for providing optimal recovery from heavy oil fields the process of reservoir characterization is demonstrated for a steam injection project at pikes peak heavy oil field near lloydminster saskatchewan canada geologic geophysical and reservoir engineering data are used to improve the interpretation of reservoir conditions there is ambiguity in modeling any of these data however in modeling all data sets in cooperative inversion ambiguity is decreased thereby enhancing our knowledge of the reservoir one of the main benefits of this oil field modeling is that bypassed oil and steam fronts are effectively mapped

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

probabilistic integration of geologic scenarios seismic and production data a west africa turbidite reservoir case study from reservoir exploration to field abandonment reservoir modeling plays a central role in understanding and predicting the reservoir key geologic geophysical and engineering components reservoir models either as a simple layer cake or as a complex fully 3d description of structural components rock and fluid properties are ideal gateways for aggregating data and expertise from different sources and disciplines the complexity of such models should be driven by the practical reservoir management question raised be it the estimation of ooip reserve question or the development and planning of wells surface facilities and recovery strategies flow question at the same time the limitation of reservoir models should be well understood reservoir models can only mimic the reservoir s true complexity they can never fully nor need they represent the actual subsurface heterogeneity

temperature dependent propagation of p and s waves in cold lake oil sands comparison of theory and experiment the measured dependence of ultrasonic velocity in cold lake oil sands on temperature is compared to theoretical model predictions for seismic wave propagation in porous media the experiments indicated that change in fluid properties with temperature most greatly affect observed velocities the theoretical model was constructed to account for temperature dependent fluid properties using correlations independent of the ultrasonic experiments theoretical and experimental p wave velocities agree within 5 percent for temperatures between 22 c to 125 c and effective stresses of 1 mpa and 8 mpa the modeling indicates that the change in fluid bulk modulus with temperature dominates the observed 15 percent p wave velocity decrease between 22 c to 125 c over the same temperature range the model predicts the s wave velocity remains almost constant 1 percent increase

variation of mineralogy and organic material during the early stages of aqueous activity recorded in antarctic micrometeorites abstract micrometeorites mms recovered from surface snow near the dome fuji station antarctica are almost free from terrestrial weathering and contain very primitive materials and are suitable for investigation of the evolution and interaction of inorganic and organic materials in the early solar system we carried out a comprehensive study on seven porous and fluffy mms four chondritic porous cp mms and three fluffy fine grained fluffy fg mms and one fine grained type 1 fg c1 mm for comparison with scanning electron microscope transmission electron microscope x ray absorption near edge structure analysis and secondary ion mass spectrometer they show a variety of early aqueous activities four out of the seven cp mms contain glass with embedded metal and sulfide gems and enstatite whiskers platelets and do not have hydrated minerals despite the same mineralogy organic chemistry of the cp mms shows diversity two of them contain considerable amounts of organic materials with high carboxyl functionality and one of them contains nitrile c n and or nitrogen heterocyclic groups with d and 15 n enrichments suggesting formation in the molecular cloud or a very low temperature region of the outer solar system another two cp mms are poorer in organic materials than the above mentioned mms organic material in one of them is richer in aromatic c than the cp mms mentioned above being indistinguishable from those of hydrated carbonaceous chondrites in addition bulk chemical compositions of gems in the latter organic poor cp mms are more homogeneous and have higher fe si mg fe ratios than those of gems in the former organic rich cp mms functional group of the organic materials and amorphous silicate in gems in the organic poor cp mms may have transformed in the earliest stage of aqueous alteration which did not form hydrated minerals three fluffy fg mms contain abundant phyllosilicates showing a clear evidence of aqueous alteration phyllosilicates in thee mms are richer in fe than those in hydrated idps typical fine grained hydrated fg c1 mms and hydrated carbonaceous chondrites one of the fluffy fg mms contains amorphous silicate which is richer in fe than gems and contains little or no nanophase fe metal but contains fe sulfide because the chemical compositions of the amorphous silicate are within the compositional field of gems in cp idps the amorphous silicate may be alteration products of gems the entire compositional field of gems in the cp mms and the amorphous silicate in the fluffy fg mm matches that of the previously reported total compositional range of gems in idps one fluffy fg mm contains mg rich phyllosilicate along with fe rich phyllosilicate and mg fe carbonate mg rich phyllosilicate and mg fe carbonate may have been formed through the reaction of fe rich phyllosilicate mg rich olivine and pyroxene and water with c bearing chemical species these data indicate that cp mms and fluffy fg mms recovered from antarctic surface snow contain materials that throw a light on the earliest stages of aqueous alteration on very primitive solar system bodies because mineralogy and isotopic and structural features of organic materials in d10ib009 are comparable with isotopically primitive idps its parent body could be comets or icy asteroids showing mass ejection active asteroids by contrast organic poor cp mms may have experienced the earliest stage of aqueous alteration and fluffy fg mms experienced weak aqueous alteration the precursor materials of the parent bodies of fluffy fg mms probably contained abundant gems or gems like materials like cp idps which is common to fine grained matrices of very primitive carbonaceous chondrites such as cr3s however highly porous nature of organic poor cp mms and fluffy fg mms suggests that parent bodies of these mms must have been much more porous than the parent bodies of primitive carbonaceous chondrites given no phyllosilicate among the returned samples of 81p wild 2 comet the mms may have been derived from porous icy asteroids such as active asteroids as well as p and d type asteroids rather than comets

modeling aqueous alteration of cm carbonaceous chondrites results from an inorganic geochemical modeling study support a scenario in which low temperature aqueous alteration of an anhydrous cm asteroidal parent body and melt water from h20 and co ices produces the altered assemblage observed in cm carbonaceous chondrites chrysotile greenalite tochilinite cronstedtite and minor calcite and magnetite we consider a range of possible precursor mineral assemblages varying with respect to the fe oxidation state of the initial anhydrous phases the aqueous solutions produced by this alteration are generally strongly basic and reducing and a large quantity of h2 and possible ch4 gas can be released during aqueous alteration

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

mineralogy of tagish lake an ungrouped type 2 carbonaceous chondrite in this paper we describe the recovery handling and preliminary mineralogical investigation of the tagish lake meteorite tagish lake is a type 2 carbonaceous chondrite which bears similarities to ci1 and cm chondrite groups but is distinct from both abundant phyllosilicates as well as chondrules however sparse and common olivine grains in the matrix preclude any other classification the bulk density of tagish lake 1 67 g cc which is far lower than ci or cm chondrites 2 2 2 3 and 2 6 2 9 g cc respectively or any other meteorite for that matter we have identified two lithologies a dominant carbonate poor lithology and a less abundant carbonate rich lithology the meteorite is a breccia at all scales we have noted similarities between tagish lake and some clasts within the enigmatic meteorite kaidun possibly there are genetic relationships here worth exploring in the paper we describe a clast of cm1 material within tagish lake which is very similar to a major lithology in kaidun

mineralogy chemistry and physical properties interrelationships of some sensitive clays from eastern canada this paper describes the use of quantitative mineralogy and specific surface area in interpreting the index properties of clayey soils from nine sites in eastern canada samples representative of t

silica diagenesis i solubility controls abstract the diagenetic sequence of silica is examined in terms of several thermodynamic and kinetic concepts the relationship between solubility and surface area or particle size is sufficient to explain simple opal a opal ct quartz transformations suggesting that the role of temperature and other physical parameters may not be as critical as previously thought complexation and adsorption in an impure system when added to the model allow for possibilities of opal a transformation directly to quartz of clay and zeolite formation from an opaline silica source and of variations in silica transformation rates due to presence of impurities in the system

pressure and temperature dependence of acoustic wave speeds in bitumen saturated carbonates implications for seismic monitoring of the grosmont formation abstractrecent time lapse seismic observations in carbonate reservoirs subject to steam assisted enhanced oil recovery display substantial changes in seismic reflectivity due to the combined effects of saturation pressure and temperature understanding these field seismic observations requires knowledge of the effects on the seismic wave speeds in bitumen saturated carbonates we have conducted ultrasonic measurements of p and s wave velocities in bitumen saturated dolomite taken from the grosmont formation in northern alberta wave speeds are measured under a variety of conditions of constant pore pressure constant effective pressure and with varying temperature to map the various controlling factors the temperature dependent declines of 12 and 9 for the p and s wave speeds respectively with temperatures from 10 c to 102 c are most notable unlike oil sands at times the dolomite retains its structure upon removal of the bitumen allowing for measurement of the dry and water saturated frame pr

microchondrule bearing clast in the piancaldoli ll3 meteorite a new kind of type 3 chondrite and its relevance to the history of chondrules in the piancaldoli ll3 chondrite we found a mm sized clast containing 100 chondrules 0 2 64 m in apparent diameter much smaller than any previously reported that are all of the same textural type radial pyroxene fs1 17 this clast like other type 3 chondrites has a fine grained ferich opaque silicate matrix sharply defined chondrules abundant low ca clinopyroxene and minor troilite and si and cr bearing metallic fe ni however the very high modal matrix abundance 63 8 vol unique characteristics of the chondrules and absence of microscopically observable olivine indicate that the clast is a new kind of type 3 chondrite most chondrules have feo rich edges and chondrule size is inversely correlated with chondrule core feo concentration the first reported correlation of chondrule size and composition chondrules acquired fe by diffusion from fe rich matrix material during mild metamorphism possibly before final consolidation of the rock microchondrules those chondrules 100 m in diameter are also abundant in another new kind of type 3 chondrite clast in the rio negro l chondrite regolith breccia in other type 3 chondrite groups microchondrule abundance appears to be anticorrelated with mean chondrule size viz 0 02 0 04 vol in h and co chondrites and 0 006 vol in l ll and cv chondrites microchondrules probably formed by the same process that formed normal sized droplet chondrules melting of pre existing dustballs because most compound chondrules in the clast and other type 3 chondrites formed by collisions between chondrules of the same textural type we suggest that dust grains were mineralogically sorted in the nebula before aggregating into dustballs the sizes of compound chondrules and chondrule craters which resulted from collisions of similarly sized chondrules while they were plastic indicate that size sorting of dustballs occurred before chondrule formation probably by aerodynamic processes in the nebula we predict that other kinds of type 3 chondrites exist which contain chondrule abundances size ranges and proportions of textural types different from known chondrite groups

early solar system processes recorded in the matrices of two highly pristine cr3 carbonaceous chondrites met 00426 and que 99177 the mineralogy and bulk compositions of the matrices of the cr chondrites met 00426 and que 99177 have been studied using a combination of sem epma and tem techniques the matrices of these two chondrites are texturally chemically and mineralogically similar and are characterized by significant feo enrichments with respect to other cr chondrite matrices nearly flat refractory lithophile patterns variable volatile element patterns and a simple mineral assemblage dominated by amorphous silicate material and fe ni sulfides fine grained crystalline silicate phases such as olivine and pyroxene appear to be extremely rare in the matrices of both meteorites instead the mineralogy of matrices and fine grained rims of both meteorites consists of abundant amorphous feo rich silicate material containing nanoparticles of fe ni sulfides troilite pyrrhotite and pentlandite secondary alteration minerals that are characteristic of other cr chondrites e g renazzo and al rais such as phyllosilicates magnetite and calcite are also rare the texture and mineralogy of the matrices of met 00426 and que 99177 share many features with matrices in the primitive carbonaceous chondrites alh a77307 co3 0 and acfer 094 unique these observations show that met 00426 and que 99177 are very low petrologic type 3 chondrites that have escaped the effects of aqueous alteration unlike other cr chondrites which are typically classified as petrologic type 2 we suggest that these meteorites represent additional samples of highly primitive but extremely rare carbonaceous chondrites of petrologic type 3 00 according to the classification scheme of grossman and brearley 2005 the highly pristine nature of met 00426 and que 99177 provides important additional insights into the origins of fine grained materials in carbonaceous chondrites based on our new observations we infer that the amorphous silicate material and nanosulfide particles that dominate the matrices of these meteorites formed in the solar nebula by rapid condensation of material following high temperature events such as those that formed chondrules

meteorite and meteoroid new comprehensive definitions abstract meteorites have traditionally been defined as solid objects that have fallen to earth from space this definition however is no longer adequate in recent decades man made objects have fallen to earth from space meteorites have been identified on the moon and mars and small interplanetary objects have impacted orbiting spacecraft taking these facts and other potential complications into consideration we offer new comprehensive definitions of the terms meteorite meteoroid and their smaller counterparts a meteoroid is a 10 m to 1 m size natural solid object moving in interplanetary space a micrometeoroid is a meteoroid 10 m to 2 mm in size a meteorite is a natural solid object larger than 10 m in size derived from a celestial body that was transported by natural means from the body on which it formed to a region outside the dominant gravitational influence of that body and that later collided with a natural or artificial body larger than itself even if it is the same body from which it was launched weathering and other secondary processes do not affect an object s status as a meteorite as long as something recognizable remains of its original minerals or structure an object loses its status as a meteorite if it is incorporated into a larger rock that becomes a meteorite itself a micrometeorite is a meteorite between 10 m and 2 mm in size meteorite a solid substance or body falling from the high regions of the atmosphere craig 1849 a mass of stone and iron that ha s been directly observed to have fallen down to the earth s surface translated from cohen 1894 a solid bod y which came to the earth from space farrington 1915 a mass of solid matter too small to be considered an asteroid either traveling through space as an unattached unit or having landed on the earth and still retaining its identity nininger 1933 a meteoroid which has reached the surface of the earth without being vaporized 1958 international astronomical union iau definition quoted by millman 1961 a solid body which has arrived on the earth from outer space mason 1962 a solid bod y which reach es the earth or the moon mars etc from interplanetary space and is large enough to survive passage through the earth s or mars etc atmosphere gomes and keil 1980 a meteoroid that survive s passage through the atmosphere and fall s to earth burke 1986 a recovered fragment of a meteoroid that has survived transit through the earth s atmosphere mcsween 1987 a solid bod y of extraterrestrial material that penetrate s the atmosphere and reach es the earth s surface krot et al 2003

mineralogy and composition of matrix and chondrule rims in carbonaceous chondrites abstract the degree of compositional variation of fine grained minerals displayed by the members within any carbonaceous chondrite group i e ci cm cv cr is a direct reflection of the range of aqueous alteration assemblages present matrix and fine grained chondrule rims within any particular carbonaceous chondrite are mineralogically nearly identical to one another but not necessarily similar in bulk elemental composition even though they have subsequently experienced post accretional secondary processing aqueous alteration under identical conditions this may indicate preferential alteration of one component brecciation exchange of components between rims and matrix and or accretion of matrix and rims from mineralogically or compositionally distinct materials we propose that co chondrites experienced parent body conditions of low f o2 low water rock ratios and temperatures below 50 c cr chondrites experienced higher water rock ratios potentially higher temperatures 150 c and a wide range of f o2 the alteration mineralogy of cv chondrites indicates water rock ratios at the high end at least of the range for cr chondrites essebi and mac 87300 cm chondrites experienced temperatures below 50 c low f o2 and low water rock ratios except eet 83334 which probably experienced relatively higher f o2 and b 7904 and y 86720 which experienced postalteration temperatures in the range 500 700 c most ci chondrites experienced temperatures between 50 and 150 c relatively high water rock ratios and variable f o2 with a late stage increase in the latter due possibly to brecciation and consequent release of methane y 82162 witnessed post alteration heating possibly as high as 400 c

vapor condensed phase processes in the early solar system abstract equilibrium thermodynamic calculations of the sequence of condensation of phases from a cooling gas of solar composition at total pressures thought to have prevailed in the inner part of the solar nebula successfully predict the primary mineral assemblages of refractory inclusions in cm2 and cv3 chondrites many refractory inclusions in cm2 chondrites contain a relatively sio2 poor assemblage spinel hibonite grossite perovskite corundum that represents a high temperature stage of condensation and some may be pristine condensates that escaped later melting compact type a and type b refractory inclusions consisting of spinel melilite perovskite ca rich clinopyroxene anorthite in cv3 chondrites are more sio2 rich and equilibrated with the solar nebular gas at a slightly lower temperature textures of many of these objects indicate that they underwent melting after condensation crystallizing into the same phase assemblage as their precursors the ti3 ti4 ratio of their pyroxene indicates that this process occurred in a gas whose oxygen fugacity was approximately 8 5 log units below that of the iron wustite buffer making them the only objects in chondrites known to have formed in a system whose composition was close to that of the sun relative to ci chondrites these inclusions are uniformly enriched in a group of elements e g ca ree zr ta ir that are chemically diverse except for their high condensation temperatures in a system of solar composition the enrichment factor 17 5 can be interpreted to mean that these objects represent either the first 5 7 wt of the condensable matter to condense during nebular cooling or the residue after vaporization of 94 3 of a ci chondrite precursor the mg and si isotopic compositions of types a and b inclusions are mass fractionated by up to 10 and 4 amu respectively when interpreted in terms of rayleigh fractionation during evaporation of mg and si from the inclusions while they were molten the isotopic compositions imply that up to 60 of the mg and up to 25 of the si were evaporated and that approximately 80 of the enrichment in refractory cao al2o3 relative to more volatile mgo sio2 in the average inclusion is due to initial condensation and approximately 20 due to subsequent evaporation the mineralogical composition including the ti3 ti4 ratio of the pyroxene in inti a particle sampled from comet wild 2 by the stardust spacecraft is nearly identical to that of a type b inclusion indicating that comets contain not only the lowest temperature condensates in the form of ices but the highest temperature condensates as well the feo feo mgo ratios of olivine and pyroxene in the matrix and chondrules of carbonaceous and ordinary chondrites are too high to be made in a system of solar composition requiring s only 1 or 2 log units below iron wustite more than 105 times higher than that of a solar gas various ways have been devised to generate cosmic gases sufficiently oxidizing to stabilize significant feo in olivine at temperatures above those where fe mg interdiffusion in olivine ceases one is by vertical settling of dust toward the nebular midplane enriching a region in dust relative to gas because dust is enriched in oxygen compared to carbon and hydrogen relative to solar composition a higher results from total vaporization of the region but the factor by which theoretical models have so far enriched the dust is 10 times too low another is by transporting icy bodies from the outer part of the nebula into the hot inner part where vaporization of water ice occurs not only does this method fail to make the needed by a factor of 30 1000 but it also ignores simultaneous evaporation of carbon bearing ices that would make the even lower

bulk mineralogical changes of hydrous micrometeorites during heating in the upper atmosphere at temperatures below 1000 c small particles 200 m in diameter from the hydrous carbonaceous chondrites orgueil ci murchison cm2 and tagish lake were experimentally heated for short durations at subsolidus temperatures under controlled ambient pressures in order to examine the bulk mineralogical changes of hydrous micrometeorites during atmospheric entry the three primitive meteorites consist mainly of various phyllosilicates and carbonates that are subject to decomposition at low temperatures and thus the brief heating up to 1000 c drastically changed the mineralogy changes included shrinkage of interlayer spacing of saponite due to loss of molecular water at 400 600 c serpentine and saponite decomposition to amorphous phases at 600 and 700 c respectively decomposition of mg fe carbonate at 600 c recrystallization of secondary olivine and fe oxide or metal at 700 800 c and recrystallization of secondary low ca pyroxene at 800 c the ambient atmospheric pressures controlled species of secondary fe phase taenite at pressures lower than 10 2 torr magnesiowstite from 10 3 to 10 1 torr and magnetite from 10 2 to 1 torr the abundance of secondary low ca pyroxene increases in the order of murchison orgueil and tagish lake and the order corresponds to saponite abundance in samples prior to heating mineralogy of the three unmelted micrometeorites f96ci024 kw740052 and kw740054 were investigated in detail in order to estimate heating conditions the results showed that they might have come from different parental objects carbonaterich tagish lake type carbonate poor tagish lake or ci type and cm type respectively and experienced different peak temperatures 600 700 and 800 900 c respectively at 60 80 km altitude upon atmospheric entry

a microstructural investigation of osaka bay clay the impact of microfossils on its mechanical behaviour a recent microstructural investigation of osaka bay clay sediments has revealed the presence of abundant microfossils particularly in the marine layers which appear to influence directly the micr

the porosity and permeability of chondritic meteorites and interplanetary dust particles abstract we have investigated the porosity of a large number of chondritic interplanetary dust particles idps and meteorites by three techniques standard liquid gas flow techniques a new noninvasive ultrasonic technique and image processing of backscattered images the latter technique is obviously best suited to sub kilogram sized samples we have also measured the gas and liquid permeabilities of some chondrites by two techniques standard liquid gas flow techniques and a new nondestructive pressure release technique we find that chondritic idps have a somewhat bimodal porosity distribution peaks are present at 0 and 4 porosity a tail then extends to 53 type 1 3 chondrite matrix porosities range up to 30 with a peak at 2 the bulk porosities for type 1 3 chondrites have the same approximate range as exhibited by the matrix which indicates that other components of the bulk meteorites including chondrules and aggregates have the same average porosity as the matrix these results reveal that the porosities of primitive materials at scales ranging from nanogram to kilogram are similar which implies that similar accretion dynamics operated through 12 orders of size magnitude permeabilities of the investigated chondrites vary by several orders of magnitude and there appears to be no simple dependence of permeability with degree of aqueous alteration chondrite type or porosity

fluid substitution in rocks saturated with viscoelastic fluids heavyoilshavehighdensitiesandextremelyhighviscosities and they exhibit viscoelastic behavior traditional rock physics based on gassmann theory does not apply to materials saturated with viscoelastic fluids we use an effective medium approach known as coherent potential approximation cpa as an alternativefluid substitutionschemeforrockssaturatedwithviscoelasticfluids suchrocksaremodeledassolidswithellipticalfluidinclusions when fluid concentration is small and as suspensions of solid particles in the fluid when the solid concentration is small thisapproachisconsistentwithconceptsofpercolationandcritical porosity and it allows one to model sandstones and unconsolidated sands we model the viscoelastic properties of a heavyoil saturated rock sample using cpaand a measured frequencydependent complex shear modulus of the heavy oil comparison of modeled results with measured properties of the heavy oil rock reveals a large discrepancy over a range of frequencies and temperatures we modify the cpascheme to account for the effect of binary pore structure by introducing a compliant porosity term this dramatically improves the predictions the predicted values of the effective shear modulus of the rock are in good agreement with laboratory data for the range of frequencies and temperatures this confirms that our scheme realistically estimates the frequency and temperature dependent properties of heavy oil rocks and can be used as an approximate fluid substitutionapproachforrockssaturatedwithviscoelasticfluids

a new variant of saponite rich micrometeorites recovered from recent antarctic snowfall abstract eight saponite rich micrometeorites with very similar mineralogy were found from the recent surface snow in antarctica they might have come to earth as a larger meteoroid and broke up into pieces on earth because they were recovered from the same layer and the same location of the snow synchrotron x ray diffraction xrd analysis indicates that saponite mg fe carbonate and pyrrhotite are major phases and serpentine magnetite and pentlandite are minor phases anhydrous silicates are entirely absent from all micrometeorites suggesting that their parental object has undergone heavy aqueous alteration saponite serpentine ratios are higher than in the orgueil ci chondrite and are similar to the tagish lake carbonaceous chondrite transmission electron microscope tem observation indicates that serpentine occupies core regions of fine grained saponite pyrrhotite has a low ni concentration and mg fe carbonate shows unique concentric ring structures and has a mean molar mg mg fe ratio of 0 7 comparison of the mineralogy to hydrated chondrites and interplanetary dust particles idps suggests that the micrometeorites are most similar to the carbonate poor lithology of the tagish lake carbonaceous chondrite and some hydrous idps but they show a carbonate mineralogy dissimilar to any primitive chondritic materials therefore they are a new variant of saponite rich micrometeorite extracted from a primitive hydrous asteroid and recently accreted to antarctica

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

the microstructure of semarkona and bishunpur abstract the ordinary chondrites semarkona and bishunpur appear to have experienced in situ hydrous alteration here we report the results of the first detailed tem examination of them which supports this conclusion in semarkona all but the most magnesian mafic minerals have been destroyed and primary sulphides most likely troilite have been partially altered to phyllosilicates and ni rich pyrrhotite in bishunpur alteration is confined to the production of smectite from an amorphous feldspathic material in the chondrule rims and interchondrule matrix during hydrous alteration of both meteorites the temperature probably did not exceed 260 c the equilibrium composition of the gas present during the alteration of semarkona was not solar but was dominated by h2o the formation of smectite does not require the presence of liquid water however evidence for the redistribution of elements such as ca zn and si over tens of microns or more implies that there was at least some transient grain boundary fluid present the alteration in semarkona and bishunpur is far from complete thermodynamic modelling suggests that more altered ordinary chondrites would be mineralogically similar to the cm and ci carbonaceous chondrites superficially the mineralogy mineral chemistry and bulk chemistry of semarkona matrix rims resemble those of some chondritic interplanetary dust particles cidps the ordinary chondrite parent bodies may therefore be a source of some cidps

matrix mineralogy of the orgueil ci carbonaceous chondrite a petrographic and transmission electron microscopic study of the orgueil ci carbonaceous chondrite shows that the matrix consists mainly of fe bearing mg rich serpentine and smectite saponite as well as a poorly crystallized fe rich material that contains minor variable s and ni the fe rich material is probably ferrihydrite a ferric hydroxide the ferrihydrite occurs in small particles 80 a in diameter and the s and ni are probably adsorbed on its surfaces the serpentine and saponite occur in poorly crystallized fine crystallites fine phyllosilicates that are intimately associated with the ferrihydrite coarsely crystallized phyllosilicates coarse phyllosilicates occur in clusters relatively free of ferrihydrite the ferrihydrite is a major matrix constitutent and probably accounts for most of the fe3 as well as the superparamagnetic fraction in the orgueil matrix the textures suggest that the fine phyllosilicates resulted from alteration of the coarse phyllosilicates the alteration probably involved a substantial amount of water and coincided with the period of sulfate vein formation during the aqueous alteration magnetite grains disaggregated from framboids and fe ni sulfides were replaced by ferrihydrite simultaneously aqueous solutions reacted with the coarse phyllosilicates and precipitated ferrihydrite producing intimate pervasive mixtures with the fine phyllosilicates the matrix mineralogy of the orgueil chondrite suggests that orgueil experienced considerably different alteration conditions from the cm chondrites the mineralogical and petrological differences between ci and cm chondrites can not simply be explained as the result of different degrees of aqueous alteration

automated thin film analyses of anhydrous interplanetary dust particles in the analytical electron microscope abstract an automated 200 kev analytical electron microscope was used to obtain elemental analyses from over 4000 points on ultramicrotomed thin sections of eight layer silicate class interplanetary dust particles idps each analysis yielded major and minor element abundances from a volume approaching that of a cylinder 50 nm in diameter multi element cluster analysis was employed to identify mineral phases and their relative abundances in the thin sections petrographic characteristics were determined using brightfield and darkfield imaging lattice fringe imaging and electron diffraction three of the particles contained smectite 1 0 1 2 nm basal spacing and two contained serpentine 0 7 nm basal spacing the mineralogy of three of the eight idps appears to have been modified by heating possibly during atmospheric entry the point count analyses and mg si fe ternary diagrams show that one of the serpentine containing idps is similar to ci and cm chondritic meteorites but the fine scale heterogeneity among the other seven is distinct from these meteorites which are more uniform on a 50 nm scale the idps exhibit evidence of aqueous processing but they have typically experienced only short range submicrometer scale alteration in comparison ci and cm chondrites are compositionally more uniform presumably as a result of more extensive aqueous alteration the hydrated layer silicate idps may provide a broad sampling of the asteroid belt including samples of the outer p and d asteroid classes

behavior of mexico city clay subjected to undrained repeated loading this note describes a series of cyclic triaxial tests on undisturbed soil samples of mexico city clay obtained near the sct building the site is a silty clay deposit of a very high water content and soft consistency the material exhibits elastic behavior in spite of its very high water content three empirical relationships describing an equivalent young s modulus an equivalent damping ratio and a cyclic stress level associated with cyclic strain level were obtained test results define two different patterns of strength loss

comprehensive examination of large mineral and rock fragments in stardust tracks mineralogy analogous extraterrestrial materials and source regions abstract transmission electron microscopy examination of 87 large fragments from 16 carrot shaped and bulbous stardust sd tracks was performed to study the range and diversity of materials present in comet wild 2 olivines and low ca pyroxenes represent the largest proportions of fragments observed however a wide range of minerals and rocks were found including probable ferromagnesian al rich and si rich chondrule fragments a refractory inclusion possible matrix mineral lithic clasts and probable condensate minerals these materials combined with fine grained components in the tracks are analogous to components in unequilibrated chondrite meteorites and cluster interplanetary dust particles idps two unusual lithologies in the bulbous tracks are only observed in chondritic porous idps and may have direct links to idps the absence of phyllosilicates indicates that comet wild 2 may be a dry comet that did not accrete or form significant amounts of hydrated phases some large mineral fragments in the sd tracks are analogous to large mineral idps the large variations of the coarse grained components within and between all 16 tracks show that comet wild 2 is mineralogically diverse and unequilibrated on nearly all scales and must have accreted materials from diverse source regions that were widely dispersed throughout the solar nebula

gems like material in the matrix of the paris meteorite and the early stages of alteration of cm chondrites abstract the paris meteorite is a weakly altered cm chondrite that has been discovered recently hewins et al 2014 its matrix offers the opportunity to search for well preserved pristine pre accretional material as well as to study the earliest stages of aqueous alteration in the cm parent body the study of the matrix of paris has been conducted by analytical transmission electron microscopy on focused ion beam sections extracted from matrix areas showing different degrees of aqueous alteration the least altered matrix sample consists of amorphous silicate grains a few hundreds of nm in size separated from one another by an abundant porosity the amorphous silicates enclose numerous fe sulfide nanograins and their average composition is close to the chondritic composition they share many similarities with gems glass with embedded metal and sulfides grains present in chondritic porous interplanetary dust particles and with primitive type 3 0 carbonaceous chondrites this first discovery of gems like texture in a cm chondrite suggests that gems grains could have been the building blocks of the cm matrices in more aqueously altered samples pronounced microstructural heterogeneities were detected at the micrometer scale the matrix consists mostly of a mixture of amorphous material and fe rich spongy to fine fibrous poorly crystalline phyllosilicates the porosity fraction is significantly reduced and the mixed amorphous fibrous material frequently forms a continuous groundmass the close association between these two material types suggests a replacement mechanism due to aqueous alteration chemical compositions correlate strongly with the microstructure the amorphous material has a composition close to the chondritic value while the fine fibrous phyllosilicate material is fe enriched this fe enrichment is found to be continuous from weakly to more heavily altered areas in which the fibrous morphology is coarser and better crystalline cronstedtite with intercalated tochilinite is also found but in pore spaces this chemical evolution concomitant with the maturation of the phyllosilicates demonstrates that the early aqueous fluids that interacted with silicates in the matrix were enriched in fe this composition is probably the consequence of the preferential dissolution of metal and iron sulfides during the first stages of alteration the enrichment of phyllosilicates in mg seen in more altered cm chondrites is not observed in paris

relationships between organics water and early stages of aqueous alteration in the pristine cr3 0 chondrite met 00426 abstract in order to investigate the nature of organics at the time of their accretion into chondrite parent bodies as well as their subsequent evolution with aqueous alteration we have conducted a study of the morphologies spatial distribution and relationships between organic particles and the surrounding matrix phases in one of the most pristine carbonaceous chondrites currently known met 00426 cr which is therefore likely to contain the best preserved record of pre accretion features focused ion beam sections were extracted for transmission electron microscope observations from its matrix organic matter om shows a heterogeneous population of grains most of them smaller than 1 m diverse morphologies are observed such as compact rounded aggregates individual and aggregated nanoglobules and micron to nanometer sized veins a common feature is the systematic presence of cracks connected to the grains and filled with om the surrounding matrix groundmass consists of amorphous iron rich silicate particles intimately mixed with phyllosilicates sulfides and occasional tochilinite with sizes ranging from several hundreds of nanometers to below 10 nm a close spatial relationship is commonly observed between some of the organic matter particles and alteration phases such as tochilinite and phyllosilicates phyllosilicates sometimes occur intimately intercalated with organic matter at a scale below 10 nm we used tem eds techniques to quantify the water concentration in the matrix amorphous silicate material and the phyllosilicates the water contents of both materials are identical at 10 6 wt h 2 o and demonstrate that the amorphous silicate material in this meteorite is hydrated therefore even though these cr3 0 chondrites are the least altered objects from a mineralogical point of view their matrices contain significant amounts of water in the amorphous silicate this coupled in situ study of organics and aqueous alteration suggests that a significant population of the om accreted as a mixture of soluble and insoluble molecules together with water ice grains and that the om was mobile at the micrometer scale the spatial distribution of the om grains can therefore in part be attributed to parent body processes we suggest that as accreted ice melted hydration of the amorphous silicates and formation of tochilinite and phyllosilicates occurred in the immediate vicinity of the composite water ice organic matter grains the water soluble component of the organics was likely transported and redistributed in the surrounding porosity cracks grain boundaries as water circulated the textural settings suggest that some of the om material could have been polymerized during aqueous alteration and transformed into insoluble molecules perhaps during the last stages of alteration as water was consumed by silicate hydration reactions

elastic property changes in a bitumen reservoir during steam injection the hangingstone steam assisted gravity drainage sagd operation of japan canada oil sands limited jacos is approximately 50 km south southwest of fort mcmurray in northern alberta canada jacos started the operation in 1997 and has produced bitumen since 1999 the oil sands reservoirs in hangingstone occur in the lower cretaceous mcmurray formation and are about 300 m in depth the sedimentary environments are fluvial to upper estuarine channel fill and the oil sands reservoirs correspond to vertically stacked incised valley fill with very complex vertical and horizontal distribution

seismic attributes for monitoring of a shallow heated heavy oil reservoir a case study in production geophysics detecting the zones of production or constraining the in situ conditions within a reservoir are often of greater importance than obtaining highly resolved seismic structural images standard seismic data processing distorts the signal and limits the potential for extracting additional information especially for shallow targets an alternative shift stack procedure is applied in the processing of a shallow 12 fold 1 m common midpoint cmp spacing reflection profile acquired over a heated athabasca heavy oil sand reservoir the shift stack involves summing of cmp traces which have been flattened to an appropriate reference event simple modeling confirms that the prestack waveforms are better preserved by this process amplitude and frequency attributes are extracted from the reflection profile amplitudes of a continuous reservoir event vary by 600 over 35 m intervals along the profile bright spots correlate with heated regions apparent frequencies as measured by the instantaneous frequency and by short time window power spectral estimates of the subreservoir event are 20 30 hz lower in these same regions these diminished apparent frequencies most probably result from interference of the subreservoir reflection with events related to structural changes within the reservoir a complete interpretation of the results has not been attempted as knowledge of the in situ conditions is incomplete however changes in the seismic response at the well locations suggest that these attributes are useful in detection and mapping of heated zones the shiftstack procedure may also be useful in environmental and geotechnical applications

singularities of geotechnical properties of complex soils in seismic regions volcanic activity results in a wide range of soil types with very unusual characteristics the most remarkable of which are volcanic ash clays containing the clay minerals allophane and imogolite in addition to these soils volcanic activity often produces the special environmental conditions that result in the formation of diatomaceous soils namely water rich in dissolved silica these soils consist of individual particles containing intraparticle voids filled with water resulting in a very unique porous particle morphology that is quite different than stereotypical sedimentary soils this paper presents a series of careful laboratory tests on samples of both materials found in chile these tests demonstrate that soils weathered from volcanic ash develop yield pressures that are similar to the preconsolidation pressure of sedimentary soils this type of soil also shows a dramatic change in properties due to drying in addition diatomaceous soils and those containing allophane have very low densities in spite of which they develop remarkably high shear strength the need for their properties to be properly understood and taken into account in geotechnical design especially seismic design is emphasized since the location of these soils generally coincides with earthquake activity which like volcanic activity arises from tectonic plate interaction

geologic structure and groundwater flow in the pachuca zumpango sub basin central mexico this paper is a hydrogeologic characterisation of the pachuca zumpango sub basin in central mexico mainly concerned with the shallow geologic structure of the region and its implications in groundwater flow the structure is interpreted as a series of graben structures limited by normal faults of metrical surface displacement the graben are filled by a sequence of approximately 2 000 m alluvial and pyroclastic material and lava flows an upper aquifer that consists of quaternary tertiary lava flows and clastic material is intensively used to obtain water for municipal supply abstraction was carried out with no control or management policy and resulted in severe environmental impacts numerical modelling simulation scenarios with continuous increments in the abstraction rate of 0 660 m3 s in 5 year periods between 2000 and 2020 predict an overall increase in depth to potentiometric surface of 15 m 0 80 m year soil consolidation computation in terms of calculated drawdown values was not an objective in this study however lowering of the potentiometric surface will eventually control soil subsidence as observed elsewhere in mexico city

amorphous silica materials in soils and sediments of the ex lago de texcoco mexico an explanation for its subsidence abstract mexico city is built on the sediments of the former texcoco lake ex lago de texcoco which are characterised by the presence of a siliceous deposit up to 70 m in thickness called jaboncillo like soap the jaboncillo is composed dominantly of amorphous silica and iron oxides and hydroxides with minor amounts of phyllosilicates and detrital volcanic minerals the mineralogy the micromorphology and physical and chemical properties are discussed the optical isotropic groundmass consists largely of amorphous silica and iron hydroxides the bulk density calculated for the dry material is about 0 26 g cm 3 its water retention capacity is extremely high up to 522 at field capacity but this characteristic is partly lost after drying also the high solubility of si the high cec and cole are irreversibly reduced after drying due to a denser packing of the originally randomly distributed hydrated silica spheres therefore it is evident that drainage will irreversibly change physical characteristics and increase risk of instability and subsidence of the sediments when used for construction

fayalitic olivine in matrix of the krymka ll3 1 chondrite vapor solid growth in the solar nebula fayalitic olivine fa54 94 is a ubiquitous component in the matrix of krymka ll3 1 as well as in other highly unequilibrated chondrites ordinary and carbonaceous in krymka the fayalitic olivine has an unusual anisotropic platy morphology that occurs in at least five types of textural settings that can be characterized as 1 isolated platelets 2 clusters of platelets 3 euhedral to subhedral crystals 4 overgrowths of platelets on forsteritic olivine and 5 fluffy porous aggregates from transmission electron microscope tem investigation the direction of elongation of the platy olivine overgrowths on forsteritic olivine substrates is along the c axis and in most cases it corresponds with the c axis of the substrate olivine which suggests that the fayalitic olivine grew in this unusual morphology and is not a replacement product of preexisting material the fayalitic olivine in the matrix of krymka is compositionally similar to olivine with platy morphology in the matrix of some cv3 chondrites and both have similar fe mn ratios but important morphological differences indicate that their relationship needs to be explored further textural and compositional data indicate that the fayalitic olivine in the matrix of krymka as well as in some other unequilibrated ordinary chondrites formed prior to final lithification of the meteorite and probably prior to parent body accretion we find that formation of the fayalitic olivine by vapor solid growth provides the best explanation for our observations and data and is the only feasible mechanism for the formation of fayalitic olivine in the matrix of krymka we propose that the fayalitic olivine formed by vaporization and recondensation of olivine rich dust during a period of enhanced dust gas ratio in the nebula

aqueous alteration in five chondritic porous interplanetary dust particles abstract analytical electron microscope analysis of stratospheric micrometeorites show that layer silicates are common albeit minor constituents in five particles of the nominally anhydrous subclass of chondritic porous cp interplanetary dust particles idps these layer silicates are single crystal na k rich smectite minerals illite kaolinite and less common pyrophyllite mica and rare talc rare non stoichiometric crystalline feldspars of probable authigenic origin occur in cp idp w7029e5 the feldspars are low anorthite and undetermined na k alkali feldspar polymorphs similar al2o3 al2o3 sio2 ratios and alkali content of feldspars and layer silicates suggest a genetic relationship between these minerals whereby layer silicates form during aqueous alteration in the case of cp idp w7029e5 alteration occurred in a mildy acidic ph 5 7 fluid at 175 195 c if cp idps are solid debris from short period comets the observations give evidence for mineralogical and chemical activity in nuclei of short period comets if an asteroidal origin for these cp idps can be established these observations provide a window to the processes that may ultimately lead to fully hydrated carbonaceous chondrite matrices

petrography of refractory inclusions in cm2 6 que 97990 and the origin of melilite free spinel inclusions in cm chondrites queen alexandra range que 97990 cm2 6 is among the least altered cm chondrites known it contains 1 8 vol refractory inclusions 40 were studied from a single thin section inclusion varieties include simple banded and nodular structures as well as simple and complex distended objects the inclusions range in mean size from 30 to 530 m and average 130 90 m many inclusions contain 25 15 vol phyllosilicate predominantly mg fe serpentine several contain small grains of perovskite in addition to phyllosilicate the most abundant inclusions in que 97990 consist mainly of spinel pyroxene 35 followed by spinel 20 spinel pyroxene olivine 18 pyroxene 12 pyroxene olivine 8 and hibonite spinel 8 four pyroxene phases occur diopside al rich diopside with 8 0 wt al2o3 al ti diopside i e fassaite and in two inclusions enstatite no inclusions contain melilite aqueous alteration of refractory inclusions transforms some phases particularly melilite into phyllosilicate some inclusions broke apart during alteration melilite free phyllosilicate bearing spinel inclusions probably formed from pristine phyllosilicate free inclusions containing both melilite and spinel sixty five percent of the refractory inclusions in que 97990 appear to be largely intact the major exception is the group of spinel inclusions all of which are fragments whereas que 97990 contains about 50 largely intact refractory inclusions cm2 estimates from literature data imply that more altered cm chondrites have lower modal abundances and lower number densities of refractory inclusions mighei cm 2 3 contains roughly 0 3 0 6 vol inclusions 10 largely intact inclusions cm2 cold bokkeveld cm2 2 contains 0 01 vol inclusions on the order of 6 largely intact inclusions cm 2

mexico city soil behavior at different strains observations and physical interpretation the unique mechanical properties of mexico city soils plot as extreme values on most geotechnical engineering charts the purpose of this study is to analyze salient properties and to propose conceptual models to explain them in particular mechanical parameters synthesized from published laboratory data are systematically organized in terms of strain level three strain regions are identified the threshold strains at the boundaries between these strain regions are examined in terms of microscale processes that participate at different strains

heavy oils their shear story heavy oils are important unconventional hydrocarbon resources with huge reserves and are usually exploited through thermal recovery processes these thermal recovery processes can be monitored using seismic techniques shear wave properties inparticular areexpectedtobemostsensitivetothechanges in the heavy oil reservoir because heavy oils change from being solid like at low temperatures to fluid like at higher temperatures to understand their behavior we measure the complex shearmodulusandthusalsotheattenuationofaheavy oil saturated rock and the oil extracted from it within the seismic frequency band in the laboratory the modulus and quality factor qoftheheavy oil saturatedrockshowamoderatedependence on frequency but are strongly influenced by temperature the shear wave velocity dispersion in these rocks is significant at steam flooding temperatures as the oil inside the reservoir loses viscosity atroomtemperatures theextractedheavyoilsupports a shear wave but with increasing temperature its shear modulus decreases rapidly which translates to a rapid drop in the shear modulus of the heavy oil saturated rock as well at these low to intermediate temperatures 30 c 100 c an attenuation peak corresponding to the viscous relaxation of the heavy oil is encountered also resulting in significant shear wave velocity dispersion well described by the cole cole model thus shearwaveattenuationinheavy oilrockscanbesignificantlylargeand iscausedbyboththemeltingandviscousrelaxationoftheheavy oil at yet higher temperatures the lighter components of the heavy oil are lost making the oil stiffer and less attenuative the dramaticchangesinshearvelocitiesandattenuationinheavyoils should be clearly visible in multicomponent seismic data and suggestthatthesemeasurementscanbequalitativelyandquantitatively used in seismic monitoring of thermal recovery processes

mineralogy and texture of fe ni sulfides in ci1 chondrites clues to the extent of aqueous alteration on the ci1 parent body to better understand the role of aqueous alteration on the ci1 parent body we have analyzed the texture composition and mineral associations of iron nickel sulfides in four of the five known ci1 chondrites the most commonly occurring sulfide present in the ci1 chondrites is the iron deficient fe ni sulfide pyrrhotite fe ni 1 xs that has a composition close to that of stoichiometric troilite fes three of the ci1s alais ivuna and tonk also contain pentlandite fe ni 9s8 although pentlandite is a rare phase in ivuna cubanite cufe2s3 was found in both alais and ivuna in this study although it has also been reported in orgueil macdougall and kerridge 1977 the pyrrhotite grains in all four chondrites form hexagonal rectangular or irregular shapes and show no evidence of ni or co zoning the pyrrhotite grains in orgueil and ivuna are in general smaller and show more corrosions or embayments than those in alais or tonk we suggest that the precursor sulfide present in the ci1 chondrites was troilite which during brecciation and oxidation on the parent body at a temperature of 100 c or less converted the troilite to magnetite and pyrrhotite with pentlandite inclusions subsequently continued alteration on the parent body removed pentlandite partially from alais tonk and ivuna completely from orgueil leaving behind pyrrhotite with spaces corrosions where the pentlandite had been ni derived from the pentlandite was incorporated into ferrihydrite onto the surface of which the ni na sulfate ni bloedite formed based on the size and abundant corrosions within pyrrhotite grains combined with observations from other authors we conclude that orgueil and ivuna have undergone a greater degree of alteration than alais and tonk further work is needed to assess the conditions under which pentlandite would be dissolved preferentially to pyrrhotite as the study of terrestrial literature indicates that the latter mineral is preferentially removed

mineralogy aqueous alteration and primitive textural characteristics of fine grained rims in the y 791198 cm2 carbonaceous chondrite tem observations and comparison to alha81002 abstract transmission electron microscopy tem was used to study the microtextural and mineralogical characteristics of fine grained rims in the unbrecciated cm2 chondrites y 791198 and alha81002 in an effort to provide constraints on the origins of the rims themselves our tem observations show that the rims in y 791198 are composed of two distinct types of region sulfide poor and sulfide rich that are intermixed in a complex manner at the micron to submicron level the sulfide poor regions are largely composed of amorphous silicate material or nanocrystalline serpentine but rare fibrous and coarse grained serpentine grains have also been identified no fine grained cronstedtite or tochilinite were observed although coarse grained lumps of tochilinite are present in the rims in contrast the sulfide rich regions are characterized by the presence of a myriad nanometer sized fe ni sulfide grains pentlandite with some ni rich pyrrhotite embedded within an amorphous silicate similar in composition to that of the sulfide poor regions the sulfide rich regions also contain rare phases such as olivine and fe ni metal grains with grain sizes that are always 100 nm in size z contrast scanning transmission electron microscopy stem reveals that the fine grained rims consist of a mosaic of irregularly shaped sulfide poor and sulfide rich regions with sizes of about 0 2 0 5 m that have been compacted together during parent body lithification despite aqueous alteration the distinct mineralogical characteristics of these different regions are preserved on a fine scale and probably represent primitive heterogeneity in the dust from which these rims formed serpentine is much better developed and more widespread in the fine grained rims of alha81002 than y 791198 complex mats of serpentine fibers are commonly found and cronstedtite and tochilinite are plentiful anhydrous minerals such as olivine are rare and have usually been replaced by serpentine like y 791198 all the fine grained rims studied in alha81002 show the same mineral assemblages and textural characteristics throughout and between rims the homogeneity of the mineralogy textural relationships and degree of hydration in the rims of these two chondrites is more consistent with parent body alteration than with pre accretionary alteration

connection between micrometeorites and wild 2 particles from antarctic snow to cometary ices we discuss the relationship between large cosmic dust that represents the main source of extraterrestrial matter presently accreted by the earth and samples from comet 81p wild 2 returned by the stardust mission in january 2006 prior examinations of the stardust samples have shown that wild 2 cometary dust particles contain a large diversity of components formed at various heliocentric distances these analyses suggest large scale radial mixing mechanism s in the early solar nebula and the existence of a continuum between primitive asteroidal and cometary matter the recent collection of concordia antarctic micrometeorites recovered from ultra clean snow close to dome c provides the most unbiased collection of large cosmic dust available for analyses in the laboratory many similarities can be found between antarctic micrometeorites and wild 2 samples in terms of chemical mineralogical and isotopic compositions and in the structure and composition of their carbonaceous matter cosmic dust in the form of concordia antarctic micrometeorites and primitive idps are preferred samples to study the asteroid comet continuum

mineralogy of phyllosilicate rich micrometeorites and comparison with tagish lake and sayama meteorites abstract four phyllosilicate rich micrometeorites mms were investigated by a synchrotron radiation x ray diffraction technique and transmission electron microscopy three are saponite rich mms and one is a serpentine rich one in the saponite rich mms we could not find serpentine and vice versa in the serpentine rich mm in the saponite rich mms major constituent minerals are saponite fe and ni bearing sulfides and magnetite two saponite rich mms contain fine grained magnesiowustite rich aggregates the aggregates consist of

transmission electron microscopy of concordia ultracarbonaceous antarctic micrometeorites ucamms mineralogical properties we performed mineralogical and petrographic studies of three ultracarbonaceous antarctic micrometeorites ucamms by analytical transmission electron microscopy tem the ucamms were identified in the concordia micrometeorite collection 2002 and 2006 recovered from central antarctic snow and are of probable cometary origin ucamms are dominated by disordered carbonaceous matter that extends over surfaces of up to 90 of the particle embedded in this carbonaceous matter we observed small and complex assemblages of fine grained mineral phases isolated minerals glassy phases that resemble glass with embedded metal and sulfides gems that were first found in interplanetary dust particles idps and rounded objects containing both glass and crystalline materials the mineral assemblages are chondritic in composition within a factor of 2 crystalline materials represent at least 25 of mineral phases this value is much larger than the upper limit of crystallinity measured in the diffuse interstellar medium 2 2 wt crystalline phases are dominated by low ca mg rich pyroxenes mg rich olivine and low ni fe sulfides exotic phases such as mn zn rich sulfide and perryite have also been found as accessory minerals the variety of high temperature mineral phases observed in ucamms is similar to that reported in chondritic porous idps and 81p wild 2 samples the close association of high temperature crystalline phases with the low temperature carbonaceous matter in ucamms supports the hypothesis of a large scale radial mixing in the early solar nebula this new type of carbon rich micrometeorites containing crystalline material provides the opportunity to analyze in situ without any chemical processing the association of materials formed at both low and high temperatures in the protoplanetary disk a better knowledge of these samples is also important to prepare for future cometary missions like rosetta in 2014

physical chemical and mineralogical properties of mexico city sediments a geotechnical perspective the authors appreciate the interest of the discussers in the paper and offer the following comments as indicated in the paper the results presented were obtained as part of a comprehensive research program on the microstructure of mexico city sediments being conducted at the national university of mexico a second site has been studied and the corresponding paper has been written in which correlation of the profiles of geotechnical properties of the sediments with their profiles of physical chemical and mineralogical properties has been investigated the discussers compare the mexico city sediments with illitic sensitive clays in canada the united states and norway we believe their discussion estimates in an alternate scenario which did not in our judgement optimally represent the circumstances of the just case the focus of our article principally mexico city sediments are predominant disintegration products of andesitic rocks and fine and ultrafine volcanic ash furthermore the discussers indicate that variations in carbonate content may have only a small influence on observed variations in the engineering behavior of deposits with high water content which is the case for mexico city sediments all of the ramon lopez velarde park core was checked with scanning electron microscopy and we did not find carbonate precipitation except at a depth of 4 m from the surface so the role of carbonate cementation is doubtful phase contacts are developed in highly compacted clays or cemented clays and are distinguished by the presence of direct contacts between the structural elements and by a new phase carbonates developed at the contacts cementing the particles coagulation contacts are widespread in young clays and poorly cemented clays the structural elements do not directly touch each other and structural cohesion is de termined by molecular and possibly magnetic and dipole interaction furthermore the coagulation contacts allowed the soil to reach a restructured form after it was altered which happened in the mexico city sediments the authors agree that the processes by which the amorphous material content is determined are chemically aggressive as suggested by the discussers overall however the authors feel that the role of the amorphous material is mainly responsible for the properties of mexico city sediments the authors will investigate further quantitative interpretations in mexico city sediments

mineralogy and oxygen isotope systematics of magnetite grains and a magnetite dolomite assemblage in hydrated fine grained antarctic micrometeorites

cometary dust in antarctic ice and snow past and present chondritic porous micrometeorites preserved on the earth s surface abstract chondritic porous interplanetary dust particles cp idps collected in the stratosphere are regarded as possibly being cometary dust and are therefore the most primitive solar system material that is currently available for analysis in laboratories in this paper we report the discovery of more than 40 chondritic porous micrometeorites cp mms in the surface snow and blue ice of antarctica which are indistinguishable from cp idps the cp mms are botryoidal aggregates composed mainly of sub micrometer sized constituents they contain two components that characterize them as cp idps enstatite whiskers and gems glass with embedded metal and sulfides enstatite whiskers appear as 2 o 6 rich high ca pyroxene roedderite k na 2 mg 5 si 12 o 30 and carbonaceous nanoglobules these components have previously been discovered in primitive solar system materials such as the cp idps matrices of primitive chondrites phyllosilicate rich mms ultracarbonaceous mms and cometary particles recovered from the 81p wild 2 comet the most outstanding feature of these cp mms is the presence of kosmochlor rich high ca pyroxene and roedderite which suggest that they have building blocks in common with cp idps and cometary dust particles and therefore suggest a possible cometary origin of both cp mms and cp idps it is therefore considered that cp mms are cp idps that have fallen to earth and have survived the terrestrial environment

the primitive matrix components of the unique carbonaceous chondrite acfer 094 a tem study the mineralogical and chemical characteristics of the fine grained matrix 53 m of the unique primitive carbonaceous chondrite acfer 094 have been investigated in detail by scanning electron microscopy sem and analytical transmission electron microscopy atem generally the fine grained matrix represents a highly unequilibrated assemblage of an amorphous material small forsteritic olivines 200 300 nm low ca pyroxenes 300 400 nm and fe ni sulfides 100 300 nm the matrix is basically unaffected by secondary processes only minor amounts of serpentine and ferrihydrite as products of hydrous alteration are present texturally the amorphous material acts as a groundmass to olivines pyroxenes and sulfides mostly exhibiting rounded or elongated morphologies only very few clastic mineral grains have been found the texture and chemical composition of the amorphous material are consistent with an origin by disequilibrium condensation in either the cooling solar nebula or a circumstellar environment as such the amorphous material may be considered as a possible precursor of matrix materials in other types of chondrites the non clastic matrix olivines fo98 99 and pyroxenes en97 100 are suggested to have formed either by condensation in the solar nebula under highly oxidizing conditions or by recrystallization from the amorphous material the formation of these grains by fragmentation of chondrule components is unlikely due to chemical and microstructural reasons rapid cooling caused the observed intergrowths of clino orthoenstatite in the mg rich matrix pyroxenes although some similarities exist comparing the fine grained matrix of acfer 094 with the matrices of the unequilibrated c03 chondrite alha77307 and the unique type 3 chondrite kakangari acfer 094 remains unique since it contains the highest measured concentrations of circumstellar sic and the second highest of diamond highest is orgueil it seems reasonable to suggested that at least parts of the amorphous material in the fine grained matrix may be of circumstellar origin

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

effect of oil composition on fluid substitution in heavy oil reservoirs unlike light oils heavy oils do not have a well established scheme for modelling elastic moduli from dynamic reservoir properties one of the main challenges in the fluid substitution of heavy oils is their viscoelastic nature which is controlled by temperature pressure and fluid composition here we develop a framework for fluid substitution modelling that is reliable yet practical for a wide range of cold and thermal recovery scenarios in producing heavy oils and that takes into account the reservoir fluid composition grounded on the effective medium theories for estimating elastic moduli of an oil rock system we investigate the effect of fluid composition variations on oil rock elastic moduliwith temperature changes the fluid compositional behaviour is determined by flash calculations elastic moduli are then determined using the double porosity coherent potential approximation method and the calculated viscosity based on the fluid composition an increase in temperature imposes two opposing mechanisms on the viscosity behaviour of a heavy oil sample gas liberation which tends to increase the viscosity and melting which decreases the viscosity we demonstrate that melting dominates gas liberation and as a result the viscosity and consequently the shear modulus of the heavy oils always decrease with increasing temperature furthermore it turns out that one can disregard the effects of gas in the solution when modelling the elastic moduli of heavy oils here we compare oil rock elastic moduli when the rock is saturated with fluids that have different viscosity levels the objective is to characterize a unique relation between the temperature the frequency and the elastic moduli of an oil rock system we have proposed an approach that takes advantage of this relation to find the temperature and consequently the viscosity in different regions of the reservoir