mineralogical characterization of a unique material having heavy oxygen isotope anomaly in matrix of the primitive carbonaceous chondrite acfer 094 abstract we report the mineral compositions and micro texture of the isotopically anomalous 17 18osmow 180 fe s ni o material recently discovered in matrix of the primitive carbonaceous chondrite acfer 094 sakamoto n seto y itoh s kuramoto k fujino k nagashima k krot a n and yurimoto h 2007 oxygen isotope evidence for remnants of the early solar system primordial water science 317 231 233 synchrotron radiation x ray diffraction and transmission electron microscopy studies indicate that this material consists of the symplectitically intergrown magnetite fe3o4 and pentlandite fe5 7ni3 3s8 with magnetite pentlandite volume ratio of 2 3 magnetite forms column shaped grains 10 30 nm in diameter and 100 200 nm in length pentlandite occurs as worm shaped grains or aggregates of grains 100 300 nm in size between magnetite crystals although both the x ray diffraction and electron energy loss spectra support identification of iron oxide as magnetite the electron diffraction patterns show that magnetite has a weak 3 fold superstructure possibly due to ordering of vacancies we infer that the isotopically anomalous symplectite formed by sulfurization and oxidization of metal grains either in the solar nebula or on an icy planetesimal the intersite cation distribution of pentlandite suggests that timescale of oxidation was no longer than 1000 years

what can we learn about crustal structure from thermal data thermal data represent a valuable remote sensing aid in studying crustal evolution heat flow q results from the heat loss by the cooling earth and from the heat production a of the radiogenic elements brought to the upper crust by magmatic intrusives heat flow is often observed to be linearly related to heat production the slope of this relation or thermal depth d has been used to infer a global upward enrichment in heat producing elements this thermal depth has been equated with the thickness of granites but such an interpretation has not been confirmed everywhere the depth to which granitic plutons are rooted can be computed from the inversion of gravity data it averages 7 2 km and is much smaller than the thermal depth granulite facies rocks are assumed to be present in the lower crust on the basis of seismic and geochemical data these rocks are generally depleted or initially poor in radiogenic elements u th k it is suggested that the thermal depth reflects the depth to the depleted layer in continental regions and that it corresponds to the granulitic layer in most places worldwide thermal and seismic data support this relationship although surface heterogeneities introduce complications thermal data can therefore be used to constrain the structure of the crust and its evolution through time

shear wave processing of sonic log waveforms in a limestone reservoir sonic full waveforms were recorded in a shale limestone interval with an experimental 12 channel acoustic logging device well defined shear pseudo rayleigh waves were observed throughout most of the 142 m interval and were used to distinguish lithologic boundaries and zones of fracturing as interpreted by logs the high signal to noise ratio of the waveforms permitted meaningful shear velocities to be obtained by intervals in this well a correlation of changes in the vp vs ratio with depth aided in identifying some compositional changes in the well but such a correlation could not be used to distinguish fracturing in the limestone shear wave amplitudes however were effective for identifying lithologic changes as well as fractures from the sonic log shear amplitudes were lower in the shale than in the limestone and shear wave attenuation increased in fractured zones there was no strong correlation between the degree of fracturing and the attenuation of stoneley waves in general shear wave pr

heat flow provinces reconsidered abstract the concept of a heat flow province an area in which there is apparently a linear relationship between near surface heat flow and radiogenic heat generation is considered the relationship has been suggested for a wide variety of tectonic terrains ranging in age from archaean to cenozoic it is expressed as q q 0 a 0 d in which q and a o are the measured heat flow and heat generation and q o and d are interpreted to be the uniform reduced heat flow from the mantle and lower crust and d is a scale depth for the distribution of radiogenic elements reported values for d are in a remarkably narrow range and are typically 10 km however there can be substantial uncertainties associated with the data in particular heat generation measurements from a limited number of sites may not adequately represent even a relatively uniform pluton when the data are re analysed with reasonable estimates of uncertainty associated with them the calculated values of q o and d are in most cases significantly different from those calculated without regard to uncertainties in the data only the data from the sierra nevada batholith a deep seated plutonic complex appear to satisfy the relationship even when their uncertainties are taken into account with the re analysis d generally falls in the approximate range 10 20 km this is also the range of depths to a commonly observed discontinuity in the mid to lower crust sometimes called the conrad discontinuity which suggests a possible correlation between the two a model in which blocks of crust 10 20 km thick depths being randomly arranged are each assigned a uniform heat generation randomly generated from a reasonable range produces an apparent relationship between heat flow and heat generation that is at least as good as most of those deduced from real data the model produces crustal temperatures that are generally considerably lower in the lower crust than those commonly calculated this is consistent with the observations from seismic refraction that the depth to the moho can vary widely even in stable shield environments it is concluded that the concept of a heat flow province as originally expounded is invalid

high precision oxygen three isotope analyses of anhydrous chondritic interplanetary dust particles abstract oxygen three isotope ratios of three anhydrous chondritic interplanetary dust particles idps were analyzed using an ion microprobe with a 2 m small beam the three anhydrous idps show 17o values ranging from 5 to 1 which overlap with those of ferromagnesian silicate particles from comet wild 2 and anhydrous porous idps for the first time internal oxygen isotope heterogeneity was resolved in two idps at the level of a few per mil in 17o values anhydrous idps are loose aggregates of fine grained silicates 3 m in this study with only a few coarse grained silicates 2 20 m in this study on the other hand wild 2 particles analyzed so far show relatively coarse grained few m igneous textures if anhydrous idps represent fine grained particles from comets the similar 17o values between anhydrous idps and wild 2 particles may imply that oxygen isotope ratios in cometary crystalline silicates are similar independent of crystal sizes and their textures the range of 17o values of the three anhydrous idps overlaps also with that of chondrules in carbonaceous chondrites suggesting a genetic link between cometary dust particles wild 2 particles and most anhydrous idps and carbonaceous chondrite chondrules

the variation of heat generation density and seismic velocity with rock type in the continental lithosphere abstract the petrophysical properties radioactive heat generation compressional wave velocity and density are related to rock type in crystalline rocks the cation fraction in the rock forming minerals is applied to determine the relationships quantitatively heat generation exhibits considerable variation with rock type as well as with the geologic age of the rocks therefore the relation between heat generation and rock type has been split into a relation for phanerozoic rocks and another for precambrian rocks which exhibit significantly lower heat generation only 1 3 of that of phanerozoic rocks the interrelations between the petrophysical properties are applied to fennoscandia precambrian terrane and southern bavaria northern alpine foreland phanerozoic rocks to estimate the heat generation by radioactivity in the crust and the heat flow density from the upper mantle

experiment on estimating thermal conductivity of sedimentary rocks from oil well logging geologic note oil well are an important source of geothermal data for studying regional tectonics reconstructing the evolution of sedimentary basins and theorizing petroleum generation migration and accumulation a more satisfactory less laborious method of estimating the thermal conductivity of sedimentary rocks is badly needed the thermal conductivity of cores from two gas wells in france was measured and correlated with neutron porosity index sonic interval travel time bulk density and gamma ray logs to obtain reasonable predictions of conductivity data were segregated into lithologic groups such as sand shale carbonate shale and carbonate sand a set of regression coefficients in the equation that predicts the conductivity from the logs was calculated for each group t e correlation coefficients between the measured and predicted conductivities of the core samples were 0 81 0 75 and 0 61 respectively for the three lithologic groups the average percent difference between the measured and the calculated conductivities for the lithologies likely to be encountered in practice is 13 4 we expect this figure can be reduced to 10 by enlarging the data base for calculating the regression coefficients in the same basin or oil field the relative errors from well to well probably will be 6 or smaller because the lithology will be nearly homogeneous

the interaction of a pacific cold front with shallow air masses east of the rocky mountains abstract the study presented here describes the interactions that occurred between an advancing pacific cold front and shallow gulf of mexico and arctic air masses situated east of the rocky mountains during the verification of the origins of rotation in tornadoes experiment vortex field campaign on 17 18 april over oklahoma and adjacent states these interactions were driven largely by the complex topography of the region four air masses of distinctly different origin i e pacific polar high altitude continental gulf of mexico and arctic and the boundaries that separated them i e pacific cold front dryline and arctic front were observed within the experimental domain this event produced more than 1 million worth of damage in the experimental domain due to severe weather a dense network of ground based in situ and remote observing systems and two research aircraft equipped with in situ sensors and doppler radars gathered data that allowed the authors to document the passage of a vigoro

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

the measurement of thermal conductivity of solids with a transient linear heat source on the plane surface of a poorly conducting body abstract during the last ten years the transient hot wire method for measuring thermal conductivity of ocean bottom muds and other soft materials has been adapted for measuring the conductivity of solid rocks because it is cheaper and quicker than the steady state methods such as the divided bar this is done by embedding the hot wire in the form of a hypodermic needle or a ribbon flush into the surface of a block of a poorly conducting material when a flat surface of a specimen is placed on the surface of such a sensor the line source can be said to diffuse heat into an infinite half space if one neglects the heat absorbed by the poorly conducting block into which the needle is embedded the rate of the temperature rise of the line source with respect to the logarithm of time elapsed since turning on the heater is inversely proportional to the conductivity in practice the rates of temperature rise are compared for the unknown and for a standard specimen a fused silica plate in our case the percentage of the total heat flowing into the sensor block is in general different for the standard and for the unknown thus possibly creating an error when the conductivity of the sensor block is neglected it was determined experimentally that the temperature rise for a silica plate is decreased only by 1 3 by the heat absorbed by the material of the sensor block an empirical equation is proposed to correct errors arising from this source this correction needs to be used only for materials of conductivity less than 2 mcal cm c s the equation gives somewhat larger but still acceptable conductivity values for substances in the range of 0 208 3 25 mcal cm c s as shown in table 1 and fig 2 for measurements on common rocks corrections for the heat diffused into the material of the sensor block can be neglected

estimating thermal conductivity in sedimentary basins using lithologic data and geophysical well logs a method for estimating in situ thermal conductivity profiles in oil and gas wells is advanced to rectify a major shortcoming in thermal analyses of sedimentary basins thermal conductivity estimates are made in a two stage procedure and are based on a model for the conductivity of mixtures and input data from lithological and geophysical logs first rock matrix conductivity for an arbitrary depth interval i e drill cuttings sample interval which is about 3 m is determined from the laboratory calibrated conductivities and volumetric representation of its individual lithologic components using a geometric mean model in situ conductivity is then estimated by a second application of the model correcting for temperature and porosity determined from geophysical logs the method is illustrated for three uinta basin utah wells that penetrate a series of tertiary sandstones shales and muddy carbonates detailed lithologic descriptions together with sonic and neutron logs were digitized and used for estimating in situ conductivity the validity of the method was tested by comparing the prediction against laboratory measurements on 565 samples from the same wells rock matrix thermal conductivity ranges from 1 6 to 6 8 w m k and is predicted within 20 of the actual measurement for 90 of the samples both in situ conductivity values and variations for a given lithologic unit are reduced at increased porosity and increased temperature thermal conductivity nomograms are presented as useful tools to predict directly the in situ thermal conductivit of a formation from a well log signal

thermophysical properties of the earth s crust in situ measurements from continental and ocean drilling knowledge of the variation of thermal conductivity and heat production with depth is critical to understanding the thermal state of the crust continental and oceanic drill holes provide unique opportunities for the calibration of empirical and theoretical models relating crustal thermal properties to physical and chemical properties these calibrations are based on more than 30 000 well log measurements of acoustic velocity both compressional and shear density porosity radioelement concentrations k u th and major element chemistry al si ca fe s mg na in formations ranging in age from 5 to 620 ma and in composition from granitic to gabbroic the mineralogical data available from induced gamma ray spectroscopy logs when combined with known mineral thermal conductivities in a model for the thermal conductivity of a crystalline aggregate enable the in situ application of a laboratory estimation technique and yield continuous conductivity profiles however mineralogy based conductivity models cannot account for the anisotropic conductivity observed in foliated metamorphic rocks a phonon conduction model which utilizes acoustic velocity and bulk density measurements is accurate within 15 in both isotropic and anisotropic formations of the upper continental crust and in oceanic crustal layers 2c and 3 in oceanic crustal layers 2a and 2b however the effects of fracturing on compressional and shear velocities lead to inaccurate results the heat flow heat production relationship which provides one method of determining subsurface heat production has well documented limitations allis 1979 and rybach and buntebarth 1982 1984 on the basis of laboratory measurements have proposed quantitative relationships between heat production and rock compositional and physical properties the well log k u and th data indicate that heat production can be predicted from compositional data within a factor of 2 or 3 predictions of heat production from acoustic velocity and bulk density measurements are only accurate to within an order of magnitude three factors account for these results 1 the natural variability of velocity and density for a given rock composition 2 the tendency of u and th to associate with secondary rather than primary minerals and 3 u and th redistribution through fluid flow and metamorphism thus seismic velocity based heat production profiles can at best be taken as first order estimates which may misrepresent the complexity of the continental crust however the correlation of formations of known heat production with subsurface structures when combined with a suite of existing techniques for estimating heat production may lead to more accurate results

late formation of a comet wild 2 crystalline silicate particle pyxie inferred from al mg chronology of plagioclase we examined the al mg isotope systematics of plagioclase in a feo poor ferromagnesian wild 2 particle c2092 7 81 1 0 named pyxie using a 2 m spot three analyses show average 27al 24mg ratio of 65 and excess 26mg value of 0 1 4 5 0 1 4 5 2 indicating no resolvable 26mg excess in the particle the inferred initial 26al 27al 0 ratio of plagioclase in pyxie is estimated as 0 6 4 5 10 6 0 6 4 5 10 6 with an upper limit of 4 10 64 10 6 the result is very similar to that of the feo rich ferromagnesian particle iris ogliore et al 2012 assuming homogeneous distribution of 26al in the early solar system pyxie formed at least 2 6 ma after the oldest ca al rich inclusions this minimum formation age is marginally younger than formation ages of most chondrules in type 3 0 chondrites but comparable with those of mg 98 chondrules in cr3 chondrites considered in conjunction with similar oxygen isotope ratios between pyxie and iris and mg 98 chondrules in cr3 chondrites it is inferred that the ferromagnesian wild 2 particles and mg 98 chondrules in cr3 chondrites formed late in local disk environments that had similar oxygen isotope ratios and redox states

oxygen isotopic composition of coarse and fine grained material from comet 81p wild 2 abstract individual particles from comet 81p wild 2 collected by nasa s stardust mission vary in size from small sub m fragments found in the walls of the aerogel tracks to large fragments up to tens of m in size found towards the termini of tracks the comet in an orbit beyond neptune since its formation retains an intact a record of early solar system processes that was compromised in asteroidal samples by heating and aqueous alteration we measured the o isotopic composition of seven stardust fragments larger than 2 m extracted from five different stardust aerogel tracks and 63 particles smaller than 2 m from the wall of a stardust track the larger particles show a relatively narrow range of o isotopic compositions that is consistent with 16 o poor phases commonly seen in meteorites many of the larger stardust fragments studied so far have chondrule like mineralogy which is consistent with formation in the inner solar system the fine grained material shows a very broad range of o isotopic compositions 70 17 o

in situ investigations of thermal conductivity heat production and past hydrothermal circulation in the cajon pass scientific drillhole california wireline logs from the cajon pass drillhole provide observations of crustal properties and processes near the san andreas fault mineralogical profiles developed from geochemical logs are combined with a technique for calculating thermal conductivity from the volume fractions of component minerals variations in the equilibrium temperature gradient correlate with conductivity contrasts and thus with lithology rather than with fluid circulation k u and th contents calculated from gamma spectroscopy logs yield heat production values which range from 1 3 to 2 4 w m averaging 1 8 w m in the section from 500 to 1800 m evidence for depletion of u relative to th raises the possibility of extensive fluid circulation in the past however discontinuity of depletion across faults suggests that the fluid regime responsible for u depletion predated san andreas faulting

geologic setting and lithologic column of the cajon pass deep drillhole the cajon pass deep drillhole penetrates a late tertiary basin developed on crystalline basement in the sw mojave desert 4 km from the san andreas fault cores continuous cuttings and geophysical logs from phase i show great diversity in rock types structure and alteration the hole encountered cajon formation arkoses granodiorite tonalite unusual megacrystic granite and augen gneiss granitic and pelitic gneisses with quartzite quartzofeldspathic orthogneiss cut by sheets of hornblende gabbro and interlayered mafic and quartzofeldspathic orthogneisses with rare calcsilicate intervals foliation and compositional layering have low dips throughout the column and layered gneisses contain 10 cm scale recumbent folds faults and alteration zones bound several rock units with low apparent dips basement cores are typically cut by steep fractures 1 mm wide that contain zeolites calcite or chlorite epidote fractures and faults decrease in abundance with depth

heat flow heat production and crustal structure in peri atlantic regions abstract a linear relationship is commonly observed between heat flow and heat generation it provides information about the distribution of radioelements with depth over large regions the linear relationship is no more tenable but points still cluster within an elongated trend in which a regression analysis provides the bulk reduced heat flow and a gross estimate of the heat production distribution with depth over the whole considered region when geological provinces share an identical heat flow heat generation relation they form a geothermal province data measurements in western europe suggest that at least two provinces should be considered one can be related to the hercynian crust and the second to the older caledonian crust we suggest that the depth obtained from thermal data corresponds to the depth of the mafic granulite layer western france south and central england share identical geothermal parameters which can be correlated with the depth of the granulitic layer down to 17 18 km data from scotland do not fit the relationship of south and central u k and present a lower slope indicating that the radiogenic enriched layer is shallow 8 10 km this correlates with the seismic structure of the caledonian crust where the granulite layer is observed at this depth data from scotland can be compared to those from norway newfoundland new hampshire and eastern appalachian crust where the same crustal composition is observed

using neural networks to predict thermal conductivity from geophysical well logs summary we present a new approach based on neural networks to predict the thermal conductivity of sedimentary rocks from a set of geophysical well logs this method is calibrated on ocean drilling program odp data which provide several thousands of conductivity measurements combined with five geophysical well logs sonic density neutron porosity resistivity and gamma ray this data set is used to train multilayer perceptrons mlp and to find an empirical relationship between well logs mlp inputs and thermal conductivity mlp output validation tests suggest that mlp provide better estimates of thermal conductivity within 15 per cent confidence level than classical linear models and still give satisfying results with sets of only four well logs if neutron porosity is included in two odp sites 863b and 1109d mlp s predictions are compared to conventional mixing methods although this latter technique gives reliable results provided that rocks description is precise enough the mlp is more straightforward does not need any extra parameter and makes predictions in good agreement with the experimental trends this method will be useful in the estimation of heat flow from data acquired in scientific and industrial boreholes

mesoscale gravity waves and their environment in the central united states during storm fest abstract in an effort to better understand mesoscale gravity waves in winter storms in the central united states their frequency of occurrence wave characteristics the general conditions under which they occur and their effects upon the weather mesoscale surface and rawinsonde data as well as radar and satellite imagery collected during the storm scale operational and research meteorology fronts and experimental system test are analyzed in addition factors affecting the ability of objective surface map analysis to properly represent the waves are investigated thirteen coherent pressure pulse events with amplitudes of 0 2 4 0 mb and periods of 1 6 h were identified in the surface pressure data during the 6 weeks of the project involving 34 of the total hours investigated a variety of wave types occurred including wavelets wave trains and singular waves the three largest amplitude events were analyzed in detail using autospectral analysis and a barnes time to space conversion objective analysis

kinematic and moisture characteristics of a nonprecipitating cold front observed during ihop part i across front structures abstract a wide array of ground based and airborne instrumentation is used to examine the kinematic and moisture characteristics of a nonprecipitating cold front observed in west central kansas on 10 june 2002 during the international h2o project ihop this study the first of two parts is focused on describing structures in the across front dimension coarsely resolved observations from the operational network and dropsondes deployed over a 200 km distance centered on the front are combined with higher resolution observations from in situ sensors doppler radars a microwave radiometer and a differential absorption lidar that were collected across a 40 km swath that straddled a 100 km segment of the front the northeast southwest oriented cold front moved toward the southeast at 8 10 m s 1 during the morning hours but its motion slowed to less than 1 m s 1 in the afternoon in the early afternoon the cold front separated cool air with a northerly component flow of 2 4 m s 1 from a 10 km wide ban

elemental and mineralogical analyses using geochemical logs from the cajon pass scientific drillhole california and their preliminary comparison with core analyses estimates of elemental and mineralogical abundances from geochemical logs are compared to preliminary chemical and modal analyses from cores in the cajon pass scientific drillhole accuracies of log computed weight percent oxide and mineralogy determinations range from 10 to 30

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

relationships between the petrophysical properties density seismic velocity heat generation and mineralogical constitution the petrophysical properties density p compressional wave velocity v p and heat generation a exhibit considerable variation with rock type to characterize a given rock quantitatively a single parameter the cation fraction expressed by the k value has been found to be suited best 100 crystalline rocks have been sampled to cover the widest possible range in k value from silicic types like granophyres and granites through granodiorites tonalites diorites gabbros amphibolites hornblendites pyroxenites to ultrabasic rocks p k a and v p were determined experimentally the latter at 0 5 kbar 50 mpa the interrelations between these properties were established by regression analysis the relation k and v p k show a linear dependence whereas a k a and a v p follow exponential laws in a w m 3 12 20 230 5 k mole cm 3 in a 22 5 8 15 g cm 3 and in a 16 5 2 74 v p km s all correlation coefficients are better than 0 9

thermal conductivity of unconsolidated sediments with geophysical applications a theoretical model for the prediction of the thermal conductivity of unconsolidated granular sediments with application to sand shale mixtures is presented the sediment is modeled as an assemblage of grains of thermal conductivity s immersed in a pore fluid of thermal conductivity in order to take into account for the thermal interactions between the grains a differential effective medium approach is used to provide a relationship between the effective thermal conductivity of the isotropic mixtures of grains saturated by the pore fluid the porosity and the thermal conductivities of the grains and pore fluid the influence of the topology of the interconnected pore space is accounted for through the use of the electrical cementation exponent m which is related to the electrical formation factor f by f m where is the interconnected porosity the main assumption of the model lies in the small contiguity between the grains this assumption holds well for unconsolidated sand shale mixture sediments as demonstrated by comparing the model to available experimental data the model offers the possibility to derive thermal conductivity profiles from downholes measurements of natural radioactivity electrical resistivity and bulk density

aqueous alteration in the matrix of the vigarano cv3 carbonaceous chondrite the matrix of vigarano a meteorite which belongs to the reduced subgroup of the cv3 chondrites contains small amounts 10 of ferrihydrite and smectite these hydrous minerals occur together as fine fibrous intergrowths between anhydrous silicate and oxide grains coarser crystals of ferrihydrite fill fractures that cut matrix minerals and smectite also lines narrow channels within olivine grains these channels may have formed by preferential alteration of olivines along 100 parallel defects formation of ferrihydrite and smectite in the matrix of vigarano was the result of mild aqueous alteration in a low temperature 150 c oxidising parent body environment partial equilibration of matrix olivines indicates that alteration was followed by thermal metamorphism with a peak temperature of 400 500 c mineralogically similar alteration products which also were formed by parent body processes have previously been described from the matrices of four cv meteorites bali grosnaja kaba and mokoia all of which belong to the oxidised subgroup this discovery of the products of oxidative aqueous alteration in vigarano has important consequences for understanding the chemical and thermal history of the cv class of meteorites

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

determination of thermal conductivity for deep boreholes two methods for thermal conductivity determinations on rock cores and fragments were tested on a suite of samples from the kontinentales tiefbohrprogramm der bundesrepublik deutschland ktb superdeep drill hole in germany they were also compared with estimates of thermal conductivity using the mineral composition of the rock and physical well logs and with in situ thermal conductivity measurements laboratory methods provide reasonably precise determinations of the thermal conductivities of both solid core 5 and drill cuttings 10 at room temperature and pressure the most common methods presently used for crystalline rocks are the steady state divided bar db technique and the transient half space line source ls sample preparation and measurement times are comparable for the db and ls with sample preparation being more time consuming on average for isotropic rocks there is little to choose from between the two methods which both give reliable values of conductivity in the vertical direction the ls is easier to set up and use in field laboratory situations which renders it the preferred method for field reconnaissance the gneissic crystalline rocks penetrated by the ktb boreholes typically have anisotropy of the order of 10 20 the db provides unambiguous values of conductivity in a given direction so its use is preferable for obtaining both principal conductivities and the vertical component anisotropy can be estimated using ls measurements in many different directions but the potential for large random errors is much greater than with the more straightforward db approach for deep research wells the difficulties of extrapolating laboratory results to in situ conditions particularly temperature present additional obstacles to determining heat flow laboratory measurements of water saturated samples under in situ conditions combined with in situ measurements and judicious use of calculations based on mineralogy and well log derived physical properties can aid in the accurate characterization of thermal conductivity in deep wells the application of different methods helped to link variations of heat flow with depth in the ktb hole to the anisotropy of thermal conductivity or thermal refraction and thus allowed the calculation of background heat flux in this geologically complex area

structure and evolution of winter cyclones in the central united states and their effects on the distribution of precipitation part i a synoptic scale rainband associated with a dryline and lee trough abstract a convective rainband which was approximately 1500 km in length and affected large areas of the central united states for about 16 h developed within an evolving winter cyclone the rainband which will be referred to as the pre drytrough rainband formed approximately 400 km ahead of a developing dryline and lee trough drytrough for short that created an elevated sloping layer of convective instability the presence of a deep pool of high potential temperature air in the middle troposphere over the south central united states advected there from the elevated terrain to the southwest i e an elevated mixed layer produced a region of warm air advection downstream of the high terrain this enhanced the lifting associated with a migrating short wave aloft and generated the pre drytrough rainband in previous studies the dryline the lee trough the elevated mixed layer and the low level jet in the central united states have generally been viewed as isolated features here the authors pre

estimation of thermal conductivity from the mineral composition influence of fabric and anisotropy measured values of thermal conductivity from crystalline rocks are compared with values calculated from the mineral content using the layered model first thermal conductivity is estimated using data based on quasi isotropic mixtures of fragments or powder second the approach is applied on core data considering the anisotropy of some rock forming minerals the numerical value of estimated thermal conductivity is controlled by the quartz content sheet silicates control anisotropy and fabric in gneisses and their thermal consequences if imformation about the fabric of the rock is available the anisotropy of minerals can be considered in a layered model and this improves the estimation of thermal conductivity from mineral contents

an observational study of fronts and frontal mergers over the continental united states abstract the stormscale operational and research meteorology fronts experiment systems tests storm fest field program was carried out over the central united states to investigate the structure and dynamics of fronts and their attendant precipitation systems adjacent to complex topography and to evaluate new observing networks and analysis techniques for mesoscale research and weather forecasting this study presents the analysis of data taken between 8 and 10 march 1992 which was the most active period of storm fest this three day observing period was characterized by the passage of an extratropical cyclone and related fronts the synoptic scale conditions related to the cyclone and frontal evolutions are described multiple frontal zones i e pacific and arctic cold fronts quasi stationary polar front dryline maritime warm front and associated regions of precipitation are documented and their origins and interactions are explored these features both well defined and subtle were observed wi

a heat generation model for continental crust based on deep drilling in the baltic shield abstract this paper presents a heat generation model for the old continental crust on the basis of a new petrological model on the origin evolution and deep structure of the crust in which petrological geochemical and geophysical data obtained from the kola superdeep borehole and other deep boreholes drilled into the crystalline basement of the east european platform are taken into account the petrological section obtained from the borehole observations was extrapolated down to the moho boundary taking into consideration the evolution and generalized seismic model of the continental crust in our model the continental crust is subdivided into three layers a granite gneiss layer 0 17 km a charnokite enderbite layer 17 30 km and a basic layer including autochthonous restites of the protocrust 30 40 km the boundaries between the layers correspond to seismic surfaces k1 and k2 the crustal contribution to heat flow is estimated to be about 25 mw m2 52 of the total heat flow for the baltic shield and the mantle heat flow is 22 24 mw m2 a comparison is made between the heat generation model obtained in this study and the ones estimated from seismic velocity structure the difference in the heat generation value between these models may originate from the differing geological and tectonic history of the sampling localities

prefrontal wind shift lines in the plains of the united states abstract in the central united states cold fronts are sometimes preceded by a surface wind shift by several hours these wind shifts are examined to determine their origins and characteristics a climatology and a case study of an autumn prefrontal wind shift are presented data collected by the recently implemented oklahoma mesonet and a network of wind profilers permit finescale analyses of the autumn prefrontal wind shift it is found that prefrontal wind shifts are associated with both lee troughs and drylines the climatology reveals that in the central united states fronts are most frequently up to 60 of them preceded by wind shifts just east of the rockies where lee troughs and drylines originate this paper focuses on a case study of a prefrontal wind shift associated with a lee trough that forms when a front approaches the lee trough the prefrontal wind shift associated with the lee trough forms in the lee of the mountains but propagates away from the mountains when downslope flow decreas

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

an interpretation of wide angle compressional and shear wave data in southwest germany poisson s ratio and petrological implications shear wave velocity especially when used with compressional wave velocity is an important constraint on estimates of the composition and physical state of the continental lithosphere we present shear velocity s models derived from high quality s wave data along three profiles in southwest germany which combine with existing p wave velocity p models to give poisson s ratio in the crust and uppermost mantle we then construct a laterally varying petrological model of the crust by comparing our p and s models with published laboratory measured rock velocities in general poisson s ratio is 0 25 in the uppermost crust 0 22 0 23 in the mid crust but reaching a low of 0 15 in the black forest low p zone and varies laterally from 0 24 to 0 30 in the lower crust the average poisson s ratio of the whole crust is everywhere about 0 25 the laminated signature of the lower crust prominent on reflection and p wave refraction data is absent on the s wave refraction data implying a strong high low alternation of poisson s ratio in the lower crust this suggests that the lower crustal laminae represent mafic silicic compositional layering for example basic sills in an originally more quartz rich lower crust rather than alternating zones of high and low pore pressure there is no evidence for a shear wave low velocity zone lvz in the black forest mid crust despite the presence of a strong p wave lvz this suggests high quartz content and the presence of pore fluids at low not high pore pressure a clear p to s converted moho reflection pm s is visible on several shots indicating that the moho is at least locally a first order discontinuity no shear wave refractions from the upper mantle are present even where strong p wave refractions are observed possibly indicating an increase of poisson s ratio with depth in the upper mantle the petrological modeling indicates that the upper and middle crust are probably of granitic composition that the mid crustal low p zones have high quartz content and that the lower crust probably consists of granulites of laterally varying bulk composition from granodioritic to gabbroic the lower crust is more mafic in areas of high reflection density on seismic reflection profiles suggesting that the laminations are caused by mafic intrusions into the lower crust either prior to the variscan orogeny or during tertiary volcanic activity

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

well log derived estimates of thermal conductivity in crystalline rocks penetrated by the 4 km deep ktb vorbohrung well log measurements of compressional and shear velocity vp vs density and temperature from the 4 km deep ktb vorbohrung pilot hole were applied in a phonon conduction model for the thermal conductivity of a crystalline solid the resulting conductivity estimates were compared with conductivities klab measured on the nearly continuous 91 recovery core previous studies have shown the log derived conductivity klog to be within 15 of klab in isotropic or flat lying anisotropic crystalline rocks the section penetrated by the ktb pilot hole includes both predominantly isotropic metabasites and highly anisotropic gneisses with foliation dips ranging from horizontal to vertical the predictions of the phonon model were accurate within 4 in the metabasites but inaccurate by as much as 23 in the gneisses the accuracy of the model in the metabasites confirms the utility of the phonon conduction approach in isotropic or weakly anisotropic rocks but the discrepancies in the anisotropic gneisses remain unexplained these relatively large discrepancies between klog and klab correspond to depths at which laboratory measurements of vs under in situ conditions deviate from the sonic log vs this suggests that sonic log determinations of vs may not be reliable in dipping anisotropic rocks alternatively the laboratory vs measurements may not constitute a representative sample or there may be errors in the phonon conduction model if the discrepancies can be tied to errors in sonic log vs measurements the phonon conduction model may provide a tool for deriving thermal conductivity profiles of the earth s crust from seismic studies of vp and vs

is there a relationship between seismic velocity and heat production for crustal rocks abstract several investigators proposed an empirical relationship between heat production and seismic velocity for rocks typical of the continental crust these relationships could allow for indirect resolution of the distribution of heat producing elements with depth new heat production data for rock samples from the pikwitonei granulite domain and the sachigo granite greenstone subprovince of the superior province do not follow these relationships indicating that heat production cannot be reliably predicted from seismic velocity these two parameters are not likely to be related as velocity depends upon the major mineral constituents of rocks whereas heat production results from radiogenic components concentrated in both major and trace minerals in rocks

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

the stress heat flow paradox and thermal results from cajon pass conventional friction models predict a substantial thermal anomaly associated with active traces of strike slip faults but no such anomaly is observed from over 100 heat flow determinations along 1 000 km of the san andreas fault the cajon pass well is being drilled to bring deep heat flow and stress data to bear on this paradox preliminary heat flows to 1 7 km in the neighboring arkoma well indicated a positive anomaly of about 30 as would be expected if frictional resistance of the fault were 50 mpa or so but the pliocene and pleistocene history of the transverse ranges particularly high rates of uplift and erosion could also explain the anomaly preliminary stress results from cajon pass and a new interpretation of regional data by mark d zoback and colleagues suggests that the maximum compressive stress near the fault is almost normal to the trace and hence the resolved shear stress is low and the fault weak although this is consistent with long standing evidence from low heat flow vexing questions remain regarding the physics of strike slip faulting the heat flow data show large variability with depth probably from three dimensional structure and an overall decrease from over 90 mw m in the upper kilometer to less than 80 mw m in the lower 300 m with no evidence of advective heat transfer whether this decreasing trend is significant and whether it continues downward to the background value 70 mw m less the radiogenic heat from overlying rocks as expected for a weak fault must be verified with data from greater depth

radiogenic heat production of crustal rocks an assessment based on geochemical data a survey of the geochemical literature and unpublished data has resulted in the classification of u th and k concentrations by rock type over 2500 data entries have been compiled permitting calculation of their radiogenic heat production in the igneous rocks mean heat production ranges from highs of 12 20 heat production units hpu wm 3 in some peralkaline intrusives through 4 hpu in acidic 2 in intermediate and 1 in basic rocks to a low of 0 3 hpu in ultramafic rocks siliceous clastic rocks generally have greater heat production 2 to 4 hpu than do chemical sedimentary rocks including the carbonates 0 4 to 2 hpu the heat production of metamorphic rocks generally depends on the radioelement contents of their igneous and sedimentary predecessors modified by metamorphic processes based on estimates of the proportion of the continental crust that specific rock types occupy the weighted mean radiogenic heat production of the upper continental crust estimated from this data base is 3 hpu

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

fracture distribution and basement structure from measurements of electrical resistivity in the basement of the cajon pass scientific drillhole california in situ deep and shallow measurements of electrical resistivity recorded with the dual laterolog in the basement of the cajon pass scientific drillhole are compared with laboratory measurements of resistivity and porosity on fracture free core samples this comparison is the basis of a simple electrical model of the pore space of the rock from which both matrix and fracture porosity are derived in parallel the analysis of borehole electrical images obtained with the formation microscanner provides a means to identify the fractures that intersect the borehole wall to evaluate their frequency and to determine their orientation further processing of these images enables us to distinguish mineralized from fluid filled fractures the comparison of laterolog derived fracture porosity computed over a large volume of rock with a pair of fracture intensity profiles obtained from the analysis of the two images of the borehole wall is the key of a new technique by which drillhole related fractures either due to hydraulic fracturing or to stress induced borehole breakouts and natural fractures either open or mineralized are discriminated the fractures in the upper part of cajon pass basement are inferred from the analysis of in situ resistivity measurements as mostly steep and mineralized

a refractory inclusion returned by stardust from comet 81p wild 2 among the samples returned from comet 81p wild 2 by the stardust spacecraft is a suite of particles from one impact track track 25 that are ca al rich and feo free we studied three particles from this track that range in size from 5 3 x 3 2 m to 15 x 10 m scanning and transmission electron microscopy show that they consist of very fine grained typically from 0 5 to 2 m al rich ti bearing and ti free clinopyroxene mg al spinel and anorthite with trace amounts of fine perovskite feni metal and osbornite tin grains in addition to these phases the terminal particle named inti also contains melilite all of these phases with the exception of osbornite are common in refractory inclusions and are predicted to condense at high temperature from a gas of solar composition osbornite though very rare has also been found in meteoritic refractory inclusions and could have formed in a region of the nebula where carbon became enriched relative to oxygen compared to solar composition compositions of ti pyroxene in inti are similar but not identical to those of fassaite from allende inclusions electron energy loss spectroscopy shows that ti rich pyroxene in inti has ti3 ti4 within the range of typical meteoritic fassaite consistent with formation under reducing conditions comparable to those of a system of solar composition inti is 16o rich with 18o 17o 40 like unaltered phases in refractory inclusions and refractory idps with grain sizes mineralogy mineral chemistry and an oxygen isotopic composition like those of refractory inclusions we conclude that inti is a refractory inclusion that formed in the inner solar nebula identification of a particle that formed in the inner solar system among the comet samples demonstrates that there was transport of materials from the inner to the outer nebula probably either in a bipolar outflow or by turbulence

a shallow water model of the diurnal dryline this study explores the diurnal variation in the movement and structure of the dryline using a one dimensional shallow water model the model is adapted to test some common theories of dryline motion including the diurnal variation in surface friction static stability inversion erosion and momentum mixing aloft these mechanisms of diurnal variation are first studied individually and then in unison a diurnal variation in the surface friction produces a model dryline that moves westward during the day in disagreement with observations and has a southerly wind maximum near midnight a diurnal variation in the static stability produces a model dryline that steepens in slope and moves eastward during the day and then surges westward at night with a southerly wind maximum 6 to 9 h after the minimum stability inversion erosion during the day produces a nearly vertical model dry front that moves eastward during the day with surface southwesterlies at sunset the model dryline surges westward with a southerly wind maximum before midnight a diurnal variation of the momentum mixing aloft has no significant effect on the model dryline results show that the combined case with a diurnal variation of surface friction inversion erosion and static stability with terrain most accurately describes the observed dryline system the westward surge depicted in the model is compared to the flow evolution of the corresponding dam break problem for a rotating fluid

thermophysical properties of the po basin rocks summary we present an analysis on thermal properties density and porosity of clastic chemical biochemical and intrasedimentary volcanic rocks collected from petroleum exploration wells of the po basin northern italy moreover we investigate the applicability of the hashin shtrikman s model for a mineral aggregate in combination with the zimmerman s model that takes pore shape into account to calculate the bulk thermal conductivity in case of macroscopically isotropic rocks deviations between predicted and measured values range from 2 2 per cent to 6 9 per cent and significantly decrease if a proper pore aspect ratio is chosen regarding the volumetric heat capacity approximate estimates were obtained by means of a weighted average of the volumetric heat capacity of the mineral grains and that of the pore filling water the differences between the computed and measured values range from 6 2 per cent to 4 9 per cent and on average the computed volumetric heat capacity is lower by 1 6 per cent the water loss during compaction and the temperature increase with depth are main factors controlling thermal properties an anisotropy effect occurs in the case of rocks rich in sheet silicates due to rotation of these minerals the vertical thermal conductivity of sheet silicates decreases exponentially with burial depth from 2 13 w m 1 k 1 at the surface to 0 52 w m 1 k 1 at 4 5 km the laboratory data allow the formulation of compaction curves

the cajon pass scientific drilling experiment overview of phase 1 the cajon pass scientific drilling project is a broad interdisciplinary experiment involving over two dozen principal scientists phase i of drilling coring and downhole experimentation began dec 8 1986 and ended april 2 1987 with the hole at a depth of 2115 m 82 m of core recovered and a wide range of downhole experiments successfully completed in this paper we briefly outline the scientific motivation for the project and provide an overview of the scientific program we also indicate some of the varied research areas in the earth sciences where data obtained in this experiment will provide unique and important insight into active in situ processes regional geologic structure and rock and fluid composition and origin

mineralogy and petrology of stardust particles encased in the bulb of track 80 tem investigation of the wild 2 fine grained material abstract we have characterized by transmission electron microscopy the mineralogy of samples extracted from the walls of the stardust track 80 more than 500 fragments were studied using conventional imaging electron diffraction and edx microanalysis two categories of particles are distinguishable in equal proportions wt the first one is comprised of relatively large crystalline grains 1 m on average dominated by silicates olivine and pyroxene they display a wide range of compositions and microstructures comparable to those found in terminal particles minor phases including magnetite and apatite are also present their occurrence suggests that the wild 2 material underwent aqueous alteration to some extent the second type of particle called gems like material is made of silica rich glassy clumps embedding iron sulfide beads and vesicles their microstructure is characteristic of thermally modified particles that have suffered strong interaction with the silica aerogel during the hypervelocity impact this melted material may form by shedding of melted and vaporized material but given the shape of the impact track and high diversity of surviving mineral compositions much of it originated from fine grained aggregates that disaggregated during the collection chemical mapping at the nano scale allowed the localization of individual components within the silica rich glass they are dominated by mg rich components with a size less than 300 nm the average composition of this thermally modified material is close to the solar abundance for the major elements fe mg and s the fine grained material has probably not been chemically fractionated in the protoplanetary disk before its incorporation in comet wild 2 unlike the sulfur depleted matrix of chondrites from these two categories of particles we deduce that wild 2 is likely made of an assemblage of relatively large evolved grains first category cemented by a fine grained material with primitive chemistry second category the pre impact configuration of the incident material deduced from this study seems comparable to the matrix of the most primitive chondrites 3 0 or to chondritic porous interplanetary dust particles

the structure and evolution of a continental winter cyclone part i frontal structure and the occlusion process the frontal structure and occlusion process in a cyclone of moderate intensity that affected the central united states in january 1995 is examined the deep warm frontal zone associated with this cyclone had a lateral extension to the southwest of the sea level pressure minimum that although characterized by cold air advection near the surface had many of the characteristics of a warm front aloft in fact this feature had a structure similar to the so called bent back fronts previously documented only in association with explosively deepening maritime cyclones the development of a warm occluded structure was investigated with the aid of a numerical simulation of the event performed using the university of wisconsin nonhydrostatic modeling system the development of the warm occluded structure was asynchronous in the vertical occurring first at midtropospheric levels and later near the surface in contrast to the classical occlusion process near the surface the warm occluded front was formed as the warm front was overtaken by the frontogenetically inactive portion of the historical coldfrontal zone at midtropospheric levels the warm occluded structure formed as a result of the cold frontal zone approaching and subsequently ascending the warm frontal zone in accord with a component of the classical occlusion mechanism the observed asynchronous evolution of the occluded structure is proposed to result from the vertical variation in vortex strength associated with the upper level potential vorticity pv anomaly that controls the cyclogenesis it is suggested that the occlusion process begins aloft where the associated vortex strength is greatest and gradually penetrates downward toward the surface during the cyclone life cycle additionally a characteristic treble clef shape to the upper level pv anomaly is shown to be a sufficient condition for asserting the presence of a warm occluded structure in the underlying troposphere

estimation of thermal conductivity and its spatial variability in igneous rocks from in situ density logging characterisation of thermal conductivity of rock and its spatial variability by laboratory measurements is costly and time consuming there is an incentive to find more cost effective and rapid methods a new empirical relationship between density and thermal conductivity for igneous rocks has been found this paper explains that the relationship is based on the rock forming processes which in turn generate typical mineral compositions based on this relationship thermal conductivity can be estimated from geophysical density loggings experience has shown that this indirect method of determining the thermal conductivity can be used to characterise the spatial variability of thermal conductivity for certain rock types the spatial data can be used in the modelling of thermal rock domains applications of the statistical relationship are presented and illustrative examples are given of how spatial variability of thermal conductivity can be estimated based on the site investigations in a crystalline bedrock environment in sweden possible deficiencies of the method are identified such as uncertainties associated with different rock forming minerals methods of improvement are also discussed

thermal conductivity from core and well log data abstract the relationships between thermal conductivity and other petrophysical properties have been analysed for a borehole drilled in a tertiary flysch sequence we establish equations that permit us to predict rock thermal conductivity from logging data a regression analysis of thermal conductivity bulk density and sonic velocity yields thermal conductivity with an average accuracy of better than 0 2 w m k 1 as a second step logging data are used to compute a lithological depth profile which in turn is used to calculate a thermal conductivity profile from a comparison of the conductivity depth profile and the laboratory data it can be concluded that thermal conductivity can be computed with an accuracy of less than 0 3 w m k 1 from conventional wireline data the comparison of two different models shows that this approach can be practical even if old and incomplete logging data are used the results can be used to infer thermal conductivity for boreholes without appropriate core data that are drilled in a similar geological setting

low level jet development during a numerically simulated return flow event the evolution of the southerly low level jet llj during a return flow event is studied using output from the penn state ncar mesoscale model version 4 three geographically different southerly lljs develop in the simulation one over the southern plains of the united states a second southwest of brownsville texas and a third over the western gulf of mexico the llj over the plains is found to form first as an inertial oscillation and later as a response to lee troughing and an elevated mixed layer that develops over the region over mexico the temperature structure over the altiplanicie mexicana mexican high plain is responsible for a locally intense low level pressure gradient east of the high plain which remains nearly stationary over two diurnal cycles the llj over the western gulf of mexico results largely from topographic blocking of the low level southerly flow by the eastern end of the neovolcanic cordillera northwest of veracruz mexico the evolution of the lower troposphere over the southern plains resembles the carlson and ludlam conceptual model for a severe storm environment but the structure of the return flow is complex when midlevel westerlies are weak mesoscale and boundary layer processes govern the development of lljs as the west and southwesterly winds increase with an approaching upper level disturbance synoptic influences overwhelm the mesoscale processes leading to a single larger scale llj

the life cycle of an undular bore and its interaction with a shallow intense cold front abstract the evolution of an undular bore and its associated wind shift spawned by the passage of a shallow surface cold front over the southern great plains of the united states is examined using surface and remote sensing observations along with output from a high resolution numerical model simulation observations show that a separation between the wind shift and thermodynamic properties of the front was induced by the formation of a bore over south central kansas around 0200 utc 29 november 2006 by the time the front bore complex passed through lamont oklahoma approximately 4 h later the bore had reached its maximum intensity and its associated wind shift preceded the trailing baroclinic zone by 20 min within several hours the bore decayed and a cold frontal passage characterized by a wind shift coincident with thermodynamic properties was observed at okmulgee oklahoma thus a substantial transformation in both the structural and dynamical characteristics of the bore as well as its relations

exposed cross sections through the continental crust implications for crustal structure petrology and evolution abstract the continental crust is exposed in cross section at numerous sites on the earth s surface these exposures which appear to have formed by obduction along great faults during continental collision may be recognized by exposures of deep crustal rocks exhibiting asymmetric patterns of metamorphic grade and age across the faults and by distinctive bouguer anomaly patterns reflecting dipping basement structure and an anomalously deep mantle from an examination of five complexes which meet these criteria it is concluded that the most prominent layering in the crust is not compositional but metamorphic the lower crust consists of granulite facies rocks of mafic to intermediate composition while the intermediate and shallow levels consist predominantly of amphibolite facies gneisses and greenschist facies supracrustal rocks respectively post metamorphic granitic intrusions are common at intermediate to shallow levels position of discontinuities in refraction velocity where present commonly correspond to changes in composition or metamorphic grade with depth the continental crust is characterized by lateral and vertical heterogeneities of varying scale which are the apparent cause of the complex seismic reflections recorded by cocorp field observations coupled with geochemical data indicate a complex evolution of the lower crust which can include anatexis multiple deformation polymetamorphism and reworking of older crustal material the complexity of the crust is thus the result of continuous evolution by recycling and metamorphism through time in a variety of tectonic environments

density and seismic velocity in relation to mineralogical constitution based on an ionic model for minerals considering silicates and spinels as a close packing of spherical ions the oxygen ions because of their relatively large ionic radius use up more than 90 of the total ionic volume the close packing of oxygen forms a framework structure with partially constant physical properties the cations including silicon are small enough to fit into the interstices between the large sized oxygen ions without widening their framework structure the idealized space filling character of the cations explains the variations in physical properties of minerals on the basis of one variable only the cation packing index labeled k value k number of cations per mole avogadro s number s molar volume this variable is used to describe the density as well as the seismic velocity it is shownthat relationships between k value and both density and seismic velocity have approximately a linear character

p t t paths and differential alleghanian loading and uplift of the bronson hill terrane south central new england late paleozoic u pb ages of sphene and 4 0 ar 3 9 ar cooling ages of amphibole and muscovite from rocks of the bronson hill terrane in connecticut and central massachusetts reflect a late paleozoic alleghanian overprinton acadian metamorphic rocks prograde alleghanian sphenes crystallized during the late pennsylvanian and eliminate the possibility that amphibole ages reflect delayed permian cooling from devonian acadian metamorphism fourteen new amphibole ages from connecticut form a north to south trend of decreasing age from 294 to 245 ma while in massachusetts four new amphibole ages together with three others from the literature produce a random carboniferous pattern seven new muscovite ages support existing data indicating uniform cooling throughout the bronson hill terrane through 350 c in the early triassic the rate of permian cooling defined by amphibole muscovite pairs increases from 4 c my in northern connecticut to 50 c my near long island sound hinged loading and hinged but delayed exhumation in the southern part of the bronson hill terrane with the hinge in central connecticut explain these ages and cooling rates as well as a southerly increasing metamorphic field gradient one dimensional thermal modeling indicates that loading of bronson hill rocks must have begun by the late mississippian the time of peak alleghanian metamorphic temperature decreases southward from early permian in northern connecticut to late permian to the south these results demonstrate that the metamorphic effects of the alleghanian orogeny are not restricted to the avalon terrane of southeastern new england on the contrary the alleghanian orogeny reset 4 0 ar 3 9 ar mineral ages recrystallized minerals partially melted felsic rocks and transposed fabrics at least as far west as the bronson hill terrane in south central new england

estimation of heat flow in oil wells based on relation between heat conductivity and sound velocity abstract based on published data it is assumed that the ratio of sound velocity to thermal conductivity exhibits a linear relation with formation temperature for most sedimentary rocks end page 1360 combination of this assumption with fourier s heat flow law yields q ln tl c tu c 1 a tl tu where tl and tu are the subsurface temperatures at the top and the bottom of an interval respectively tl and tu the sound travel times and q is the heat flow this relation has been tested in the case of 10 wells for which accurate data were available the relation generated satisfactory fits with the measured data for siliciclastic and carbonate rocks the parameters a and c take respective values of 1 039 and 80 031 heat flow q is expressed relative to the heat flow in the standard well bolderij 1 in the groningen gas field bolderij unit bu a method for estimating the relative heat flow from bottomhole tempeatures as observed during logging operations and sound travel times from well shoot in combination with sonic log data has been developed and tested in the viking and central grabens of the uk sector of the north sea in this region the mean relative heat flow using data from 120 wells is 0 601 bu with a standard deviation of 0 055 bu comparisons of calculated relative heat flow values in bu with heat flow values in si units conventionally obtained suggests that the bolderij unit is equivalent to about 77 mwm 2 end of article last page 1361

introduction background and implications of the linear heat flow heat production relationship the discovery in the late 1960s of the linear heat flow heat production relationship was a major advance in the understanding of the thermal structure of continents however although heat flow provinces have now been defined in all continents except antarctica the full implications of the relationship to deep thermal structure and the limitations of the relationship to applications in all terranes are not yet clear in addition despite major advances in the geochemical factors controlling the distribution of heat production in the crust a geochemical rationale for the relationship is lacking the relationship was originally interpreted in terms of one dimensional models but new two and three dimensional model studies suggest more complex interpretations in terms of lower crustal heat flow contributions to these problems in this special issue represent new observational geochemical and modeling studies of the relationship and a renewed attempt to understand the thermal and geochemical implications of the relationship

recent advances in rock physics the need to extract more information about the subsurface from geophysical and petrophysical measurements has led to a great interest in the study of the effect of rock and fluid properties on geophysical and petrophysical measurements rock physics research in the last few years has been concerned with studying the effect of lithology fluids pore geometry and fractures on velocity the mechanisms of attenuation of seismic waves the effect of anisotropy and the electrical and dielectric properties of rocks understanding the interrelationships between rock properties and their expression in geophysical and petrophysical data is necessary to integrate geophysical petrophysical and engineering data for the enhanced exploration and characterization of petroleum reservoirs the use of amplitude offsets s wave seismic data and full waveform sonic data will help in the discrimination of lithology the effect of in situ temperatures and pressures must be taken into account especially in fractured and u

heavily metamorphosed clasts from the cv chondrite breccias mokoia and yamato 86009 metamorphosed clasts in the cv carbonaceous chondrite breccias mokoia and yamato 86009 y 86009 are coarse grained granular polymineralic rocks composed of ca bearing up to 0 6 wt cao ferroan olivine fa34 39 ferroan al diopside fs9 13wo47 50 approximately 2 7 wt al2o3 plagioclase an37 84ab63 17 cr spinel cr cr al 0 19 0 45 fe fe mg 0 60 0 79 nepheline pyrrhotite pentlandite ca phosphate and rare grains of ni rich taenite low ca pyroxene is absent most clasts have triple junctions between silicate grains indicative of prolonged thermal annealing based on the olivine spinel and pyroxene thermometry the estimated metamorphic temperature recorded by the clasts is approximately 1100 k few clasts experienced thermal metamorphism to a lower degree and preserved chondrule like textures the mokoia and y 86009 clasts are mineralogically unique and different from metamorphosed chondrites of known groups h l ll r eh el co ck and primitive achondrites acapulcoites brachinites lodranites on a three isotope oxygen diagram compositions of olivine in the clasts plot along carbonaceous chondrite anhydrous mineral line and the allende mass fractionation line and overlap with those of the cv chondrule olivines the 17o values of the clasts range from about 4 3 to 3 0 we suggest that the clasts represent fragments of the cv like material that experienced metasomatic alteration high temperature metamorphism and possibly melting in the interior of the cv parent asteroid the lack of low ca pyroxene in the clasts could be due to its replacement by ferroan olivine during iron alkali metasomatic alteration or by high ca ferroan pyroxene during melting under oxidizing conditions

contrasting p t t paths thermochronologic evidence for a late paleozoic final assembly of the avalon composite terrane in the new england appalachians strongly contrasting pressure temperature time paths for the avalon composite terrane and the structurally overlying putnam nashoba zone in eastern new england obtained from thermochronologic and thermobarometric data are best explained by a late paleozoic underthrusting of cover rocks by the avalon composite terrane we present new ar and u pb thermochronologic data that show that in the southern hope valley zone permian 280 ma anatectic metamorphic conditions of 700 c and 6 kbar were quenched by relatively rapid cooling 12 c m y and exhumation 0 5 km m y for 40 m y in contrast peak metamorphic conditions in the putnam nashoba zone predate silurian intrusions and slower cooling 3 5 c m y began at about 400 ma one dimensional thermal modeling suggests that these two belts were not in thermal equilibrium during the permian metamorphism of the avalon composite terrane because of the absence of high grade alleghanian metamorphism in rocks overlying the avalon terrane we conclude that high grade alleghanian metamorphism in the avalon terrane occurred east of rocks now overlying it and that significant motion between avalon and this cover occurred after peak alleghanian metamorphism similarly contrasting metamorphic histories between avalon inliers willimantic window massabesic complex gneiss pelham dome and their cover rocks reveals the regional significance of this boundary the core rocks all show permian cooling but the cover rocks show post acadian cooling ages decreasing from east to west to the pelham area where hornblende ages in avalon and cover differ by only 35 rather than 80 m y model calculations show that thermal equilibrium between instantaneously thrusted blocks of rocks is generally obtained in tens of millions of years consequently underthrusting of avalon is constrained to be middle mississippian or younger because the leading edge of the underthrusting block would have been heated the longest and would have most closely approached thermal equilibrium with its cover core rocks of the pelham dome must have been relatively close to this leading edge thus carboniferous to permian underplating from a generally eastward direction best explains these thermochronologic relationships

two dimensional inverse modeling of crustal thermal regime with application to east european geotraverses the modeling of crustal thermal regimes is basically the inference of subsurface distributions of heat flow density and temperature by continuing downward the near surface measurements of heat flow density temperature thermal conductivity and heat production to account for the uncertainties in the near surface data and in the subsurface distributions of thermal conductivity and heat production and to provide explicit estimates for the uncertainties in the resulting models we have employed a bayesian inverse formulation that incorporates the a priori information on model parameters in the form of a joint gaussian probability density function and that gives the inverse solution in the form of the most probable estimates and the a posteriori covariance matrix for the model parameters to illustrate the method we apply it to the modeling of thermal regimes along east european geotraverses eegt 5 and eegt 1 using both a linear 5 point finite difference and a quadrilateral isoparametric finite element discretization two features are emphasized first we introduce an a priori autocovariance function for the heat flow density at model base to help stabilize the solution second we demonstrate the improvement in solution accuracy and resolution when a priori temperature information is available and incorporated in the inversion for the geotraverses studied the finite difference and finite element formulations yield essentially identical results although there is a substantial difference in the extent of their parameterization in general the surface and basal heat flow densities are similar in shape implying a relatively uniform total crustal heat production across the geotraverses both the heat flow densities and the crustal temperatures exhibit strong lateral variations that appear to correlate with the tectonic age the heat flow densities and temperatures are low in the precambrian east european platform relatively higher in the variscan units high in the alps and very high in the pannonian basin the results support the presence of lateral variations of up to 40 m w m 2 in the moho heat flow density provided that one accepts as reasonable an a priori standard deviation of 25 for the surface heat flow density and an uncertainty of a factor of two for the heat production finally the a posteriori and the observed surface heat flow densities match well but exceptions occur in localized regions suggesting the presence of perturbing effects that cannot be accounted for in a steady state purely conductive model

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

constraints on the formation age of cometary material from the nasa stardust mission we measured the 26 al 26 mg isotope systematics of a 5 m refractory particle coki returned from comet 81p wild 2 in order to relate the time scales of formation of cometary inclusions to their meteoritic counterparts the data show no evidence of radiogenic 26 mg and define an upper limit to the abundance of 26 al at the time of particle formation of 26 al 27 al 5 the absence of 26 al indicates coki formed 1 7 ma after the oldest solar system solids ca al rich inclusions cais the data presented here suggest that high temperature inner solar system material formed was subsequently transferred to the kuiper belt and incorporated into comets several million years following cai formation

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

a tectonic model for the late paleozoic of southeastern new england hornblende and biotite sup 40 ar sup 39 ar age spectra from rocks in south central connecticut help define a permian triassic cooling curve for the area together with petrologic and structural information a time temperature pressure strain path is established similar data for the narragansett basin in rhode island and massachusetts allow correlation of the late paleozoic histories of the two areas together these data suggest that in the late paleozoic south central new england was part of a fold thrust belt and the narragansett basin was a retroarc foreland basin nw se compression during the final assembly of pangaea resulted in se directed thrusting causing the development of clastic wedges in adjacent rhode island and massachusetts in the late carboniferous early permian a clockwise rotation of this deformation from nw to nne led to northward underthrusting and concomitant uplift of both eastern connecticut and rhode island in the permian and triassic

heat production and thermal conductivity of rocks from the pikwitonei sachigo continental cross section central manitoba implications for the thermal structure of archean crust the pikwitonei and sachigo subprovinces of central manitoba provide a cross sectional view of the superior province crust in cross section the upper to mid level crust is composed of synformal greenstone belts surrounded by tonalitic gneisses both of which are intruded by granitoid plutons this crustal structure persists downward into the granulite facies where keels of the greenstone belts can be found to constrain thermal models of the crust we measured heat production and thermal conductivity in 60 rocks from this terrain using standard gamma ray spectrometry and divided bar techniques large vertical and lateral heterogeneities in heat production in the upper crust are evident heat production is high in granites and metasedimentary rocks intermediate in tonalite gneisses and low in the portions of greenstone belts dominated by mafic meta igneous rocks in the deeper granulite facies rocks heat production decreases by a factor of two in the tonalitic gneisses and remains low in the high grad

heat production in an archean crustal profile and implications for heat flow and mobilization of heat producing elements we have measured concentrations of heat producing elements th u and k in 58 samples representative of the main lithologies in a 100 km transect of the superior province of the canadian shield from the michipicoten wawa greenstone belt near wawa ontario through a domal gneiss terrane of amphibolite grade to the granulite belt of the kapuskasing structural zone near foleyet this transect has been interpreted as an oblique cross section through some 25 km of crust uplifted along a major thrust fault and thus provides an opportunity to examine in detail a continuous profile into deep continental crust of archean age mean heat production values for these terranes based on aereal distribution of major rock types and calculated from their th u and k concentrations are michipicoten greenstone belt 0 72 w m 3 wawa domal gneiss terrane amphibolite grade 1 37 w m 3 kapuskasing granulites 0 44 w m 3 among the silicic plutonic rocks tonalites granites and their derivative gneisses the relatively large variation in heat production correlates with modal abundances of accessory minerals including allanite sphene zircon and apatite we interpret these variations as primary pre metamorphic the relatively high weighted mean heat production of the domal gneiss terrane can be accounted for by the larger proportion there of late stage th u and k rich granitoid plutons these may have been derived from the underlying kapuskasing granulite terrane leaving it slightly depleted in heat producing elements transport of th u and k therefore could have taken place in silicate melts rather than in aqueous or carbonic metamorphic fluids this conclusion is supported by the lack of a statistically significant difference in heat production between tonalites tonalite gneisses and mafic rocks of amphibolite versus granulite grade the pre metamorphic radioactivity profile for this crustal section is likely to have been uniformly low with a mean heat production value less than 1 w m 3 this result is distinctly different from measured profiles in more silicic terranes which show decreasing heat production with depth this implies fundamental differences in crustal radioactivity distributions between granitic and more mafic terranes and may be an important factor in selective reactivation of lithologically different terranes possibly resulting in preferential stabilization of basic terranes in the geological record our results indicate that a previously determined apparently linear heat flow heat production relationship for the kapuskasing area does not relate to the distribution of heat production with depth low but significant heat production 0 4 0 5 w m 3 continues to lower crustal depths with no correlation to the depth parameter from the linear relationship this low heat production may be a minimum average granulite heat production and suggests that in general heat flow through the moho is 8 10 mw m 2 lower than the reduced heat flow calculated from the heat flow heat production regression

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