partition coefficients for calcic plagioclase implications for archean anorthosites by the use of a multiple aliquot technique combined with statistical calculations to overcome effects of alteration and contamination we have determined partition coefficients d s for rare earth elements rees between natural high ca plagioclase megacrysts and their basaltic matrices some of the basalts that we investigated are shown experimentally to crystallize only high ca plagioclase over approximately a 20 30 c temperature interval below the liquidus the ree d s agree well with experimentally determined values and predict equilibrium melts for archean anorthosites that agree well with coeval basaltic flows and dikes furthermore the d s appear to be valid for both tholeiitic and alkali basalts over a range of mg numbers 34 58 and ree concentrations la from 3 50 ppm similarly calculated d s for co sc cr rb sr cs ba hf ta and th also predict equilibrium melts for anorthosites that agree reasonably well with coeval basaltic flows and dikes the apparent values for co sc and ta seem good to better than 50 whereas the standard deviations for rb and th are equal to their means making the d s of questionable value the others are useful probably to within a factor of 2 experimental studies of the d for total fe as feot indicate a value of about 04 at an oxygen fugacity slightly below that of the qfm buffer a by product of the feot experiments was the experimental d s for mgo tio2 and k2o which could be compared with the d s from natural assemblages from the d s that were determined we suggest that plagioclase megacrysts in the bad vermilion lake anorthosite were in equilibrium with melts having the composition of tholeiitic basalts at an oxygen fugacity slightly below the qfm buffer the predicted melts have an feot content of about 13 k2o of about 15 tio2 of about 1 3 a chondrite normalized ree pattern that is nearly flat at 10 to 20 chondrites with a slight depletion of lrees other incompatible trace elements at 10 to 20 chondrites and cr and co at 0 01 to 0 1 chondrites this range of compositions is essentially identical to the tholeiitic flows and dikes in archean greenstone belts we therefore suggest that the moderately fe rich tholeiites that are hosts to plagioclase megacrysts in greenstone belts form the parental melts for megacrysts which make up the bad vermilion lake anorthositic complex and probably other similar archean anorthositic complexes

volatiles in lunar felsite clasts impact related delivery of hydrous material to an ancient dry lunar crust abstract in this detailed geochemical petrological and microstructural study of felsite clast materials contained in apollo breccia samples 12013 14321 and 15405 little evidence was found for relatively enriched reservoirs of endogenic lunar volatiles nanosims measurements have revealed very low volatile abundances 2 18 ppm hydrogen in nominally anhydrous minerals nams plagioclase potassic alkali feldspar and sio2 that make up a majority of these felsic lithologies yet these mineral assemblages and clast geochemistries on earth would normally yield relatively high volatiles contents in their nams 20 to 80 ppm hydrogen this difference is particularly notable in felsite 14321 1062 that exhibits extremely low volatile abundances 2 ppm hydrogen and a relatively low amount of microstructural evidence for shock metamorphism given that it is a clast of the most evolved 74 wt sio2 rock type returned from the moon if taken at face value wet felsic magmas 1 2 1 7 wt water are implied by the relatively high hydrogen contents of feldspar in felsite clasts in apollo samples 12013 and 15405 but these results are likely misleading these felsic clasts have microstructural features indicative of significantly higher shock stress than 14321 1062 these crustal lithologies likely obtained no more water from the lunar interior than the magma body producing 14321 1062 rather we suggest hydrogen was enriched in samples 12013 and 15405 by impact induced exchange and or partial assimilation of volatiles added to the surface of the moon by a hydrated impactor asteroid or comet or the solar wind thus the best estimate for magmatic water contents of felsic lunar magmas comes from 14321 1062 that leads to a calculated magmatic water content of 0 2 wt this dry felsic magma has a slightly greater but comparable water content to the ancient mafic magmas implied by the other lithologies that we have studied based on this and expanding evidence for a significantly dry ancient or early degassed moon it is likely that some recent estimates 100 s ppm of the water abundances in the lunar parental magma ocean have been overestimated

petrology and chemistry of two large granite clasts from the moon abstract pristine granite clasts in apollo 14 breccias 14321 and 14303 have estimated masses of 1 8 and 0 17 g respectively the 14321 clast is 60 k feldspar and 40 quartz with traces of extremely mg poor mafic silicates and ilmenite the 14303 clast is roughly 33 plagioclase 32 k feldspar 23 quartz 11 pyroxene and 1 ilmenite pyroxene and ilmenite are moderately mg rich plagioclase and pyroxene are strongly zoned both clasts are severely brecciated but monomict pristine both have abundant graphic intergrowths of k feldspar with quartz unlike the majority of similar earth rocks both clasts are devoid of hydrous phases the bulk composition of the 14321 clast is similar to those of several other lunar granitic samples but the 14303 clast is unique it bears as close a resemblance to kreep as it does to other lunar granites silicate liquid immiscibility may explain why the granites are low in ree relative to kreep

cooling history of lunar mg suite gabbronorite 76255 troctolite 76535 and stillwater pyroxenite sc 936 the record in exsolution and ordering in pyroxenes we have determined cooling rates of orthopyroxene crystals from two mg suite lunar samples gabbronorite 76255 and troctolite 76535 and one terrestrial sample orthopyroxenite sc 936 from the stillwater complex on the basis of their fe mg ordering states in addition a cooling rate of 76255 was determined by modeling the formation of exsolution lamellae in pyroxenes the m1 m2 site occupancies of the orthopyroxene crystals were determined by single crystal x ray diffraction and the rate constant for the ordering reaction was used along with calibrations of the equilibrium intracrystalline fractionation of fe and mg as a function of temperature to calculate cooling rates the closure temperatures tc of cation ordering are 525 c for 76255 500 c for 76535 and 350 c for sc 936 corresponding to cooling rates of 4 10 2 c year at the closure temperature for the lunar samples and 10 6 c year for the stillwater sample a cooling rate for 76255 determined by simulating the exsolution process is 1 7 10 2 c year at a closure temperature for exsolution of 700 c the fe mg ordering cooling rate determined for 76535 reflects a complex thermal history superimposed on the initial plutonic provenance established for this sample mccallum i s schwartz j m 2001 lunar mg suite thermobarometry and petrogenesis of parental magmas j geophys res 106 27969 27983 the preservation of a crystallization age of 4 51 ga and a metamorphic age of 4 25 ga for 76535 is consistent with a model in which excavation of this sample from the lower lunar crust took place while the sample was at a temperature above the closure temperatures for the sm nd u pb and ar ar isotopic systems temperatures in excess of the isotopic closure temperatures i e 600 c in the lower lunar crust were maintained by heat diffusing from concentrations of u and th rich kreep material at the base of the crust on the other hand 76255 formed at a much shallower depth in the lunar crust 2 km and was well below its isotopic closure temperatures at the time of excavation most likely during the serenitatis basin forming impact event both lunar samples were reheated during transport to the surface and deposition in hot ejecta blankets the reheating was short lived but apparently sufficient to redistribute fe and mg in m sites in orthopyroxenes for the lunar samples the cooling rates based on fe mg ordering represent final stage cooling within an ejecta blanket

ion microprobe investigation of plagioclase and orthopyroxene from lunar mg suite norites implications for calculating parental melt ree concentrations and for assessing postcrystallization ree redistribution the lunar mg suite which includes dunites troctolites and norites makes up to 20 30 of the moon s crust down to a depth of 60 km the remainder is largely anorthosite this report focuses on norites which consist mostly of orthopyroxene and plagioclase because we have found that both phases are effective recorders of their parental melt compositions in an earlier report we analyzed orthopyroxene from twelve samples three from apollo 14 two from a 15 and seven from a 17 by sims for eight ree la ce nd sm eu dy er yb inversion of these data to estimated melt compositions yielded extremely high ree concentrations similar to kreep in this study we report sims ree data for plagioclase from these same twelve samples the major objective of this study is to estimate parental ree concentrations from both orthopyroxene and plagioclase data to see if both data inversions produce concordant melt compositions and thus better constrain the composition of melts parental to mg suite norites the estimated ree concentrations from both phases show some evidence of slight postcrystallization ree redistribution comparison of the observed ratio of ree for pyroxene plagioclase to the ratio of the ds for pyroxene plagioclase is consistent with ree redistribution which involves lree diffusing from pyroxene into plagioclase and hree diffusing from plagioclase into pyroxene however apparently these postcrystallization exchanges have not seriously affected our ability to estimate melt ree concentrations the estimated melt ree concentrations using both plagioclase and orthopyroxene are similar to high k kreep especially for melts parental to a 15 norites this study provides support for mineral trace element inversion estimates for parental melts even though these lunar crustal lithologies experienced high temperature annealing apparently the cores of plagioclase and pyroxene continue to carry a record of their igneous crystallization history

fracture toughness of a soft sandstone abstract fracture toughness of a rock material is important in the design of rock drilling boring equipment rock bursting prediction of rock drilling forces hydraulic fracturing wellbore stability and stability of jointed rock masses a series of fracture toughness tests under mode i mode ii and mixed mode i ii loading conditions were conducted on straight edge notch brazilian disk senbd specimens in an attempt to develop an empirical failure envelope under both tension shear and compression shear conditions this series of tests is the first of its kind on a naturally weakly cemented antler sandstone even though there have been published data on artificially cemented sandstones there are no data on mixed mode fracture toughness of such soft formations the senbd specimen configuration used herein provides consistent failure patterns and development of a failure envelope in the compression shear zone as well microscopic studies using thin sections of tested and untested specimens were carried out to study the fracture propagation at micro level

seismogenic structure in a tectonic suture zone with new constraints from 2006 mw6 1 taitung earthquake 1 a mw 6 1 earthquake occurred on april 1st 2006 near taitung eastern taiwan it produced significant coseismic ground displacements and a large number of aftershocks in the ensuing month this event provides an opportunity to diagnose the seismogenic structure in the southern longitudinal valley lv of eastern taiwan long viewed as one of the collision sutures between the philippine sea and the eurasian plates with precisely relocated main and aftershock hypocenters focal mechanisms for m 3 8 events and coseismic ground displacements from strong motion records we determine a main shock dislocation model our results indicate that the main shock occurred on a high angle fault azimuth 198 dip 77 the model comprises a fault with two segments the main shock and a large number of aftershocks are associated with the northern segment that exhibited predominantly left lateral strike slip motion in agreement with p wave first motions and waveform usgs solutions the southern segment exhibits a slightly larger thrust component in agreement with cmt solutions tectonically this event highlights a nne trending fault on the west side of the lv which is predominantly strike slip the aftershocks clustered to the east of the main shock which exhibit mainly thrust mechanisms indicate that shortening is still acting on the sedimentary materials deposited between the coastal and central ranges prior to collision as a result the southern lv is undergoing slip partitioning along different faults which has never been specified before

direct detection of projectile relics from the end of the lunar basin forming epoch the lunar surface a key proxy for the early earth contains relics of asteroids and comets that have pummeled terrestrial planetary surfaces surviving fragments of projectiles in the lunar regolith provide a direct measure of the types and thus the sources of exogenous material delivered to the earth moon system in ancient 3 4 billion years ago ga regolith breccias from the apollo 16 landing site we located mineral and lithologic relics of magnesian chondrules from chondritic impactors these ancient impactor fragments are not nearly as diverse as those found in younger 3 4 ga to today regolith breccias and soils from the moon or that presently fall as meteorites to earth this suggests that primitive chondritic asteroids originating from a similar source region were common earth moon crossing impactors during the latter stages of the basin forming epoch

rare earth elements and the petrogenesis of aubrites ree measurements in the bishopville aubrite confirm that oldhamite cas is the dominant ree carrier while most other phases including the major silicates are extremely ree depleted in oldhamite a variety of ree patterns are observed which could not have been produced during crystallization from a single fractionating magma although the aubrites have clearly undergone igneous processing oldhamite which is highly refractory may be a relict phase in this case whole rock ree data cannot provide information on the igneous evolution of these meteorites

an unusual clast in lunar meteorite macalpine hills 88105 a unique lunar sample or projectile debris lunar meteorite macalpine hills mac 88105 is a well studied feldspathic regolith breccia dominated by rock and mineral fragments from the lunar highlands thin section mac 88105 159 contains a small rock fragment 400 350 m in size which is compositionally anomalous compared with other mac 88105 lithic components the clast is composed of olivine and plagioclase with minor pyroxene and interstitial devitrified glass component it is magnesian akin to samples in the lunar high mg suite and also alkali rich akin to samples in the lunar high alkali suite it could represent a small fragment of late stage interstitial melt from an mg suite parent lithology however olivine and pyroxene in the clast have fe mn ratios and minor element concentrations that are different from known types of lunar lithologies as fe mn ratios are notably indicative of planetary origin the clast could either 1 have a unique lunar magmatic source or 2 have a nonlunar origin i e consist of achondritic meteorite debris that survived delivery to the lunar surface both hypotheses are considered and discussed the meteoritical society 2014

understanding the lunar surface and space moon interactions the surface of the moon is a critical boundary that shapes our understanding of the moon as a whole all geologic mapping and remote sensing techniques utilize only the outermost portion of the moon before leaving the moon for study in our laboratories all lunar samples that have been studied existed at or very near the surface with the exception of the deeply probing geophysical techniques our understanding of the interior of the moon is derived from surficial but not superficial information coupled with boundary of the lunar crust it is the lower boundary layer of the tenuous lunar atmosphere and constitutes both a source and a sink for atmospheric gases the surface is also where the moon interacts with the space environment causing changes in the physical nature of lunar materials and provides a laboratory for the study of processes that occur on all airless bodies the data obtained remotely by the galileo clementine and lunar prospector missions as well as data derived from lunar meteorites have resulted in major changes to our understanding of global distributions of chemistry and rocks this chapter summarizes the current understanding of this critical interface the surface of the moon in its role as the lower boundary of the lunar atmosphere the upper boundary of the crust and the window through which we view through remote sensing the composition of the crust and the history of the moon in this post lunar prospector time the view of the moon has changed lending new perspectives to lunar samples and lunar processes but the new view will likely remain in flux as we continue to digest the results from these recent space missions and move forward to a new era of lunar exploration despite the freshness of our perspective this is an important moment to capture

rb sr and sm nd isotopic and ree studies of igneous components in the bulk matrix domain of martian breccia northwest africa 7034 the bulk matrix domain of the martian breccia nwa 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia both 147sm 143nd and 146sm 142nd age results for mineral separates from the bulk matrix portion of breccia nwa 7034 suggest that various lithological components in the breccia probably formed contemporaneously 4 44 ga ago this old age is in excellent agreement with the upper intersection ages 4 35 4 45 ga for u pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous textured clasts consequently we confirm an ancient age for the igneous components that make up the nwa 7034 breccia substantial disturbance in the rb sr system was detected and no age significance could be gleaned from our rb sr data the disturbance to the rb sr system may be due to a thermal event recorded by bulk rock k ar ages of 1 56 ga and u pb ages of phosphates at about 1 35 1 5 ga which suggest partial resetting from an unknown thermal event s possibly accompanying breccia formation the nwa 7034 bulk rock is lree enriched and similar to kreep rich lunar rocks which indicates that the earliest martian crust was geochemically enriched this enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on mars that have been detected in studies of other martian meteorites

silica polymorphs in lunar granite implications for granite petrogenesis on the moon granitic lunar samples largely consist of granophyric intergrowths of silica and k feldspar the identification of the silica polymorph present in the granophyre can clarify the petrogenesis of the lunar granites the presence of tridymite or cristobalite would indicate rapid crystallization at high temperature quartz would indicate crystallization at low temperature or perhaps intrusive slow crystallization allowing for the orderly transformation from high temperature silica polymorphs tridymite or cristobalite we identify the silica polymorphs present in four granitic lunar samples from the apollo 12 regolith using laser raman spectroscopy typically lunar silica occurs with a hackle fracture pattern we did an initial density calculation on the hackle fracture pattern of quartz and determined that the volume of quartz and fracture space is consistent with a molar volume contraction from tridymite or cristobalite both of which are less dense than quartz moreover we analyzed the silica in the granitic fragments from apollo 12 by electron probe microanalysis and found it contains up to 0 7 wt tio2 consistent with initial formation as the high temperature silica polymorphs which have more open crystal structures that can more readily accommodate cations other than si the silica in apollo 12 granitic samples crystallized rapidly as tridymite or cristobalite consistent with extrusive volcanism the silica then inverted to quartz at a later time causing it to contract and fracture a hackle fracture pattern is common in silica occurring in extrusive lunar lithologies e g mare basalt the extrusive nature of these granitic samples makes them excellent candidates to be similar to the rocks that compose positive relief silicic features such as the gruithuisen domes

tomographic imaging of the convergent zone in eastern taiwan a subducting forearc sliver revealed abstract this paper investigates crustal features of the plate boundary in eastern taiwan by joint analysis of gravity anomaly and seismic arrival time data we found two crustal anomalies 1 two prominent high velocity high poisson s ratio anomalies in the mid to lower crust beneath the offshore area 2 several volumes of relatively high velocity high poisson s ratio rocks in the upper to mid crust beneath the central range the former is interpreted as the luzon arc and forearc blocks from east to west the latter is interpreted as uplift material from the oceanic crust scraped from the luzon forearc which forms the core of the central range the features of northward narrowing in dimension and deepening in depth of the forearc block are revealed in the velocity solution implying a subducting luzon forearc fragment in eastern taiwan the values of poisson s ratios and earthquake activity in the northern domain are generally larger than that in the southern domain suggesting that the crustal accretion process has not been completed in the northern domain of the study area our resulting velocity and poisson s ratio models provide some insight into the tectonic processes presently operating in eastern taiwan it s also suggested that the subducting luzon forarc acts as a backstop against which accreted rocks are thrust and this contact may have seismogenic potential

compton belkovich volcanic complex cbvc an ash flow caldera on the moon abstract volcanic calderas are found on earth mars venus and io and are rare but unique volcanic structures in the solar system compton belkovich volcanic complex cbvc 60 5 n 99 5 e on the far side of the moon is a unique non mare feature due to its evolved lithology regional tectonic setting its location being near the north pole far from the procellarum kreep terrane pkt and its recent association with endogenic water high resolution remote sensing observations of several structural features at cbvc such as ring faults radial faults fractures manifested by various morphological features such as domes of varied sizes and shapes and pyroclastic ash flows characterize it to be a volcanic caldera the loading of humboldtianum basin with basalts and subsequent development of extensional structures outside it along with high thorium anomaly and resulting silicic volcanism at cbvc producing central collapsed caldera could be considered as an analogy to silicic calderas on earth formed in extensional tectonic regime even though the tectonic processes involved in these two cases are entirely different the former being impact related whereas the latter involves rifting or hotspot related activities associated with extensional plate tectonics presence of high reflectance feature and its extension to the east southeast of the topographic expression and its relation with pyroclastic dispersal have been supported by radar based mini rf observations and high resolution lroc nac imagery it suggests the presence of a late stage fine pyroclastic layer within the cbvc region the diverse volcanic features that exist at the studied site indicate a series of deformation and eruption events associated with silicic magmatism and thus cbvc could be considered as an ash flow caldera on the moon here we present a detailed appraisal of various volcanic and structural features detected at cbvc through high resolution optical as well as radar observations based on the previous and present studies an evolutionary model of the area has been proposed and the petrological implications of silicic magmatic activity its manifestation evolution and association with endogenic water have been discussed

petrogenesis and chronology of lunar meteorite northwest africa 4472 a kreepy regolith breccia from the moon northwest africa nwa 4472 is a polymict lunar regolith meteorite the sample is kreep rich high concentrations of potassium rare earth elements and phosphorus and comprises a heterogeneous array of lithic and mineral fragments these clasts and mineral fragments were sourced from a range of lunar rock types including the lunar high magnesian suite the high alkali suite kreep basalts mare basalts and a variety of impact crater environments the kreep rich nature of nwa 4472 indicates that the sample was ejected from regolith on the nearside of the moon in the procellarum kreep terrane and we have used lunar prospector gamma ray remote sensing data to show that the meteorite is most similar to and most likely sourced from regoliths adjacent to the imbrium impact basin u pb and pb pb age dates of nwa 4472 phosphate phases reveal that the breccia has sampled pre nectarian 4 35 ga rocks related to early episodes of kreep driven magmatism some younger phosphate u pb and pb pb age dates are likely indicative of impact resetting events at 3 9 4 ga consistent with the suggested timing of basin formation on the moon our study also shows that nwa 4472 has sampled impact melts and glass with an alkali depleted incompatible trace element rich high sc low rb th ratios low k compositional signature not related to typical apollo high k kreep or that sampled by kreepy lunar meteorite sayh al uhaymir sau 169 this provides evidence that there are numerous sources of kreep rich protoliths on the moon

micro computed tomography imaging and probabilistic modelling of rock fracture by freeze thaw a major problem in studies of rock fracture by frost is the paucity of direct observations in space and time of the initiation and growth of microcracks and their transition to macrocracks such observations are essential to understand the location timing and controls of rock fracture by freeze thaw the aim of the present work is to image and elucidate the early stages of rock fracture by applying imaging and statistical methods to a frost weathering experiment using intact specimens of a limestone chalk and sandstone first microcomputed tomography ct is used to visualise rock fracture in three dimensions over the course of 20 freeze thaw cycles and to estimate transverse strain using a pixel based approach second probabilistic correlation functions are applied to quantify the progressive expansion of the fracture phase and associated damage to rock specimens the method of ct is demonstrated for visualising the growth and coalescence of microcracks and their transition to macrocracks fracture proceeded faster and to a greater extent in chalk relative to sandstone and the macrocracks in chalk were mostly concentric and vertical both fracture development and positive transverse strain dilation accelerated after cycle 15 suggesting that a threshold has been exceeded after which macrocracks were evident of three probabilistic correlation functions applied to the ct results the modified lineal path function which measures the continuous connectivity of the fracture phase in a specific direction reveals that damage was more extensive in the chalk than the sandstone it also allows a novel approach to define and quantify three zones of microcracking during freeze thaw cycling of anisotropic rock 1 the zone of inherent flaws 2 the zone of active microcracking and 3 the zone of weak influence during microcracking the broader significance of this work is that it provides a new approach to investigate mechanistically how frost action damages rock

geochemistry petrology and cooling history of 14161 7373 a plutonic lunar sample with textural evidence of granitic fraction separation by silicate liquid immiscibility we report new findings related to sample 14161 7373 the first analyzed lunar intrusive rock to show textural evidence for the formation of granitic material by silicate liquid immiscibility sli and geochemical evidence for separation of that material at least on a small scale from mafic residua ion microprobe analyses of rare earth element ree concentrations in silicates record the compositional evolution of this late stage assemblage for a sample whose bulk assemblage that of whitlockite monzogabbro has ree concentrations at 5 6 kreep levels the silicates have only moderately high ree concentrations the calculated ree concentrations of melt in equilibrium with pigeonite after re integration of pigeonite host and augite lamellae is approximately 2 high k kreep the high bulk ree concentrations of the assemblage are the result of a high proportion of whitlockite probably an excess i e the assemblage is a whitlockite cumulate variations in silicate ree concentrations reflect the co crystallization of whitlockite which we interpret to have begun crystallizing prior to the onset of late stage immiscibility of the felsic melt fraction calculated cooling rates based on a quantitative model of pyroxene exsolution reveal a two stage thermal history which involved initial crystallization at a minimum depth of 700 800 m during which the primary augite and pigeonite grains unmixed to form the observed host lamella pairs unusual compositional profiles close to the host lamella interface are consistent with a second stage of mild reheating followed by rapid cooling at a depth of 30 m most likely in an ejecta blanket the shallow depth of origin indicated for 14161 7373 is consistent with other studies of evolved lunar intrusive rocks supporting the interpretation that lunar qmd and granite as found among the apollo samples are late stage differentiates of high level intrusions and are not related to differentiation of deep crustal kreep reservoirs

the constitution and structure of the lunar interior the current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period missions of the 1960s including the rangers surveyors and lunar orbiters as well as earth based telescopic studies laid the groundwork for the apollo program and provided a basic understanding of the surface its stratigraphy and chronology through a combination of remote sensing surface exploration and sample return the apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean in particular the discovery of anorthite clasts in the returned samples led to the view that a large portion of the moon was initially molten and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle and plagioclase flotation cumulates that make up the crust smith et al 1970 wood et al 1970 this model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the moon the intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the moon s interior much of this new knowledge is a direct result of data acquired from the successful clementine and lunar prospector missions as well as the analysis of new lunar meteorites as will be seen results from these studies have led to many fundamental amendments to the magma ocean model much of what we know from sample analyses has been previously summarized elsewhere and only their most important aspects will be discussed in this chapter the reader is referred to the relevant chapters in the books basaltic volcanism on the terrestrial planets basaltic volcanism study project 1981 the

characterization and comparison of structural and compositional features of planetary quadrilateral pyroxenes by raman spectroscopy this study reports the use of raman spectral features to characterize the structural and compositional characteristics of different types of pyroxene from rocks as might be carried out using a portable field spectrometer or by planetary on surface exploration samples studied include lunar rocks martian meteorites and terrestrial rocks the major structural types of quadrilateral pyroxene can be identified using their raman spectral pattern and peak positions values of mg mg fe ca of pyroxene in the mg fe ca quadrilateral can be determined within an accuracy of 0 1 the precision for ca mg fe ca values derived from raman data is about the same except that corrections must be made for very low ca and very high ca samples pyroxenes from basalts can be distinguished from those in plutonic equivalents from the distribution of their mg mg mg fe and wo values and this can be readily done using point counting raman measurements on unprepared rock samples the correlation of raman peak positions and spectral pattern provides criteria to distinguish pyroxenes with high proportions of non quadrilateral components from mg fe ca quadrilateral pyroxenes

tectonic erosion and the removal of forearc lithosphere during arc continent collision evidence from recent earthquake sequences and tomography results in eastern taiwan a very common but important observation of collided and accreted volcanic arcs is that the forearc regions of these arcs are largely or even entirely missing the processes and mechanisms responsible for the removal and transport of the forearc materials from the collisional belts are thus important issues in understanding tectonics and crustal growth the young and ongoing collision between the luzon volcanic arc and the eurasian continental margin that forms the island of taiwan provides a rare opportunity to examine these processes and mechanisms as they occur from observations of a new detailed 3 d tomography combined with relocated hypocenters of two earthquake sequences occurred in 2003 and 2006 we found that the luzon forearc lithosphere initially underthrusts westward after the collision began as the collision proceeds the forearc basement then subducts eastward beneath the colliding and accreting luzon arc along a major fault system in eastern taiwan thus the luzon forearc lithosphere appears to be removed by tectonic erosion and is being transported eastward into the mantle our results from the active taiwan orogen will provide important insights for interpreting rock records from many old arc continent collisional belts in the world

silicic lunar volcanism testing the crustal melting model lunar silicic rocks were first identified by granitic fragments found in samples brought to earth by the apollo missions followed by the discovery of silicic domes on the lunar surface through remote sensing although these silicic lithologies are thought to make up a small portion of the lunar crust their presence indicates that lunar crustal evolution is more complex than originally thought models currently used to describe the formation of silicic lithologies on the moon include in situ differentiation of a magma magma differentiation with silicate liquid immiscibility and partial melting of the crust this study focuses on testing a crustal melting model through partial melting experiments on compositions representing lithologies spatially associated with the silicic domes the experiments were guided by the results of modeling melting temperatures and residual melt compositions of possible protoliths for lunar silicic rocks using the thermodynamic modeling software rhyolite melts rhyolite melts simulations predict liquidus temperatures of 950 1040 c for lunar granites under anhydrous conditions which guided the temperature range for the experiments monzogabbro alkali gabbronorite and kreep basalt were identified as potential protoliths due to their ages locations on the moon i e located near observed silicic domes chemically evolved compositions and the results from rhyolite melts modeling partial melting experiments using mixtures of reagent grade oxide powders representing bulk rock compositions of these rock types were carried out at atmospheric pressure over the temperature range of 900 1100 c because all lunar granite samples and remotely sensed domes have an elevated abundance of th some of the mixtures were doped with th to observe its partitioning behavior run products show that at temperatures of 1050 and 1100 c melts of the three protoliths are not silicic in nature i e they have 63 wt sio2 by 1000 c melts of both monzogabbro and alkali gabbronorite approach the composition of granite but are also characterized by immiscible si rich and fe rich liquids furthermore th strongly partitions into the fe rich and not the si rich glass in all experimental runs our work provides important constraints on the mechanism of silicic melt formation on the moon the observed high th content of lunar granite is difficult to explain by silicate liquid immiscibility because through this process th is not fractionated into the si rich phase results of our experiments and modeling suggests that silicic lunar rocks could be produced from monzogabbro and alkali gabbronorite protoliths by partial melting at t 1000 c additionally we speculate that at higher pressures p 0 005 gpa the observed immiscibility in the partial melting experiments would be suppressed

northwest africa 773 lunar mare breccia with a shallow formed olivine cumulate component inferred very low ti vlt heritage and a kreep connection abstract lunar meteorite northwest africa 773 herein referred to as nwa773 is a breccia composed predominantly of mafic volcanic components including a prominent igneous clast lithology the clast lithology is an olivine gabbro cumulate which on the basis of mineral and bulk compositions is a hypabyssal igneous rock related compositionally to volcanic components in the meteorite the olivine gabbro lithology exhibits cumulus textures and in our largest section of it includes some 48 olivine fo 64 to fo 70 average fo 67 27 pigeonite en 60 fs 24 wo 16 to en 67 fs 27 wo 6 11 augite en 50 fs 17 wo 33 to en 47 fs 13 wo 40 2 orthopyroxene en 70 fs 26 wo 4 11 plagioclase an 80 to an 94 and trace barian k feldspar ilmenite cr spinel re merrillite troilite and fe ni metal the mg fe ratios of the mafic silicates indicate equilibration of fe and mg however the silicates retain compositional variations in minor and trace elements that are consistent with intercumulus crystallization accessory mineralogy reflects crystallization of late stage residual melt both lithologies breccia and olivine cumulate of the meteorite have very low ti vlt major element compositions but with an unusual trace element signature compared to most lunar vlt volcanic compositions i e relative enrichment in light ree and large ion lithophile elements and greater depletion in eu than almost all other known lunar volcanic rocks the calculated composition of the melt that was in equilibrium with pyroxene and plagioclase of the cumulate lithology exhibits a kreep like ree pattern but at lower concentrations melt of a composition calculated to have been in equilibrium with the cumulate assemblage plus excess olivine yields a major element composition that is similar to known green volcanic glasses one volcanic glass type from apollo 14 in particular green glass b type 1 has a very low ti concentration and ree characteristics including extremely low eu concentration that make it a candidate parent melt for the olivine gabbro cumulate we infer an origin for the parent melt of nwa773 volcanic components by assimilation of a trace element rich partial or residual melt by a magnesian vlt magma deep in the lunar crust or in the mantle prior to transportation to the near surface accumulation of olivine and pyroxene in a shallow chamber eruption onto a volcanic surface and incorporation of components into local predominantly volcanic regolith prior to impact mixing of the volcanic terrain and related hypabyssal setting and ejection from the surface of the moon volcanic components such as these probably occur in the oceanus procellarum region near the site of origin of the green volcanic glasses found in the apollo 14 regolith

crystal chemistry of lunar merrillite and comparison to other meteoritic and planetary suites of whitlockite and merrillite merrillite also known as whitlockite is one of the main phosphate minerals along with apatite that occur in lunar rocks martian meteorites and in many other groups of meteorites signi cant structural differences between terrestrial whitlockite and lunar and meteoritic varieties warrant the use of merrillite for the h free extraterrestrial material and the systematic enrichment of ree in lunar merrillite warrants the use of re merrillite laser raman spectroscopy of extraterrestrial merrillite and terrestrial whitlockite con rms the absence of h in the former and presence of h in the latter lunar merrillite ideally mg fe 2 mn 2 2 ca18 x y ree x na2 x p si 14o56 contains high concentrations of y ree reaching just over 3 atoms per 56 o atoms or up to 18 wt as y re 2o3 in the absence of extensive si p substitution the availability of the na site limits y ree substitution to 2 atoms per 56 o atoms higher concentrations of y ree with coupled substitution of si for p to balance charge are possible but rare in lunar material intrinsically low na concentrations in lunar rocks combined with the typical formation of merrillite in late stage basaltic mesostasis or residual intercumulus melt pockets produce these high ree concentrations lunar merrillite typically contains 0 1 0 4 na atoms per 56 o atoms for comparison martian merrillite contains signi cantly higher na concentrations up to 1 7 na atoms per 56 o atoms and much lower ree concentrations meteoritic merrillite has relatively low ree contents but exists in both ca rich and na rich varieties concentrations of fe and mg in all varieties sum to near 2 atoms per 56 o atoms merrillite in lunar crustal lithologies typically has mg fe however fe rich mare basalts contain up to 1 8 fe 2

partitioning in ree saturating minerals theory experiment and modelling of whitlockite apatite and evolution of lunar residual magmas we present compositions including rees determined by ion microprobe of apatite and whitlockite in lunar rock assemblages rich in incompatible trace elements total concentrations of ree oxides in whitlockites range from 9 13 wt and those in apatites range from 0 15 to 1 wt ratios of ree concentrations in whitlockite to those in coexisting apatite range from 10 to 60 the distribution of mg and fe between apatite and whitlockite is correlated to that of coexisting mafic silicates magnesium is strongly preferred by whitlockite and fe is preferred by apatite incorporation of rees in whitlockite is dominated by the coupled substitution of 2ree3 in ca b sites vacancy in ca iia for 2ca 2 in ca b sites and ca2 na in ca iia other substitutions account for only a small portion of the rees in whitlockite over the observed concentration range thus ree concentrations become partially saturated as the primary substitution approaches its stoichiometric limit of two rees per fifty six oxygens leading to reduced whitlockite melt distribution coefficients e g decreasing from twenty five to ten for nd the ree concentrations of lunar residual melts are not depleted by whitlockite crystallization in assemblages consisting mainly of other minerals in typical proportions distribution coefficients for the rees in lunar apatite appear to be low and variable e g 0 2 0 8 for nd variations in the modal ratio of whitlockite to apatite specifically the abundance of whitlockite lead to a range of ree concentrations in the phosphates and variations in the magnitude of ree concentration ratios between whitlockite and apatite if apatite crystallizes before whitlockite or in the absence of whitlockite as textures in several samples indicate then apatite zoned in rees and apatite crystals of different ree concentrations may occur in a given sample provided there is some amount of fractional crystallization and apatite does not later equilibrate this may occur because in the absence of whitlockite in the crystallizing assemblage the rees are highly incompatible relative to the crystalline assemblage so ree concentrations in lunar residual melts increase strongly during small increments of late stage crystallization once whitlockite begins to crystallize bulk distribution coefficients for the rees although still 1 are only mildly incompatible so the change in ree concentrations of residual melts with further crystallization is small consistent with the lack of ree zoning in whitlockite the ree concentrations in lunar whitlockites are modelled as resulting mainly from equilibrium crystallization of the assemblages in which they occur metasomatism or other secondary metamorphic processes are not indicated local melt pocket equilibrium at advanced stages of crystallization may lead to variable ree concentrations and variable whitlockite apatite concentration ratios within the same sample parent melts with extremely high ree concentrations are not required in order to crystallize ree rich lunar whitlockite if modal proportions of whitlockite are low

the lunar gruithuisen silicic extrusive domes topographic configuration morphology ages and internal structure abstract the gruithuisen domes situated on the western portion of the imbrium basin rim form three tall mountains nw gamma delta totaling 780 km3 in volume the shapes of the domes are significantly different from that of mare type domes elsewhere on the moon we use data from the lunar reconnaissance orbiter lro and kaguya missions lro lunar orbiter laser altimeter lunar reconnaissance orbiter camera diviner and the kaguya imager to characterize the domes and assess models for their origin the configuration of the domes steep slopes up to 18 20 and their specific remote sensing characteristics strong downturn in the uv and results from the m3 and diviner instruments suggest that the domes formed by eruptions of highly viscous lava the estimated surface volumes of the domes vary from 20 km3 nw dome to 290 km3 gamma dome to 470 km3 delta dome the domes occur on the portion of the imbrium basin rim that is overlain by ejecta from the post imbrium iridum crater in some areas relatively high albedo smooth volcanic plains are seen within the iridum ejecta near the gruithuisen domes and low albedo mare deposits surround and embay the domes and iridum crater dating of different units and features by crater counts indicates that impact melts from the iridum basin are 3 9 ga old the domes gamma and delta are 3 8 ga and the ages of the plains near the domes vary from 2 3 to 3 6 ga a fresh impact crater exposes the internal structure of the gamma dome the most prominent features on the wall of the crater are rough blocky layers that are typical of volcanic plains in the highlands and maria around the domes the layers are interleaved with fine grained materials of higher and lower albedo and the visible orientation of the layers changes over short a few hundred meters distances these characteristics of the internal structure of the dome are consistent with eruptions of high viscosity lava rough layers that alternated with possible explosive activity fine grained materials the spatial association of the gruithuisen domes with the highland lava plains resembles the situation in which bimodal volcanism occur on earth the terrestrial association can be due to either fractional crystallization in basaltic magma reservoirs or remelting of high silica crustal materials in the first case the evolved melts appear in later stages of volcanic activity and in the second case these melts are formed near the beginning of evolution of the magmatic systems the age estimates of the gruithuisen domes and the surrounding volcanic plains are more consistent with the crustal remelting scenario however remelting of primary anorthositic crust cannot readily produce the silica rich melts and requires the presence of pre existing granite like materials formation of the domes by fractional crystallization avoids this difficulty but requires explanation of the older age of the domes relative to the volcanic plains in the surroundings a third option is that the domes are unrelated genetically to the mare deposits

rare earth element variations resulting from inversion of pigeonite and subsolidus reequilibration in lunar ferroan anorthosites we present results of a secondary ion mass spectrometry study of the rare earth elements rees in the minerals of two samples of lunar ferroan anorthosite and the results are applicable to studies of rees in all igneous rocks no matter what their planet of origin our pyroxene analyses are used to determine solid solid ree distribution coefficients d cree in low ca pyroxene cree in augite in orthopyroxene augite pairs derived by inversion of pigeonite our data and predictions from crystal chemical considerations indicate that as primary pigeonite inverts to orthopyroxene plus augite and subsolidus reequilibration proceeds the solid solid ds for orthopyroxene augite pairs progressively decrease for all rees the decrease is greatest for the lrees the ree pattern of solid solid ds for inversion derived pyroxene pairs is close to a straight line for sm lu and turns upward for rees lighter than sm the shape of this pattern is predicted by the shapes of the ree patterns for the individual minerals equilibrium liquids calculated for one sample from the compositions of primary phases using measured or experimentally determined solid liquid ds have chondrite normalized ree patterns that are very slightly enriched in lrees the plagioclase equilibrium liquid is overall less rich in rees than pyroxene equilibrium liquids and the discrepancy probably arises because the calculated plagioclase equilibrium liquid represents a liquid earlier in the fractionation sequence than the pyroxene equilibrium liquids equilibrium liquids calculated from the compositions of inversion derived pyroxenes or orthopyroxene derived by reaction of olivine are lree depleted in some cases substantially in comparison with equilibrium liquids calculated from the compositions of primary phases these discrepancies arise because the inversion derived and reaction derived pyroxenes did not crystallize directly from liquid and the use of solid liquid ds is inappropriate the lree depletion of the calculated liquids is a relic of formation of these phases from primary lree depleted minerals thus if one attempts to calculate the compositions of equilibrium liquids from pyroxene compositions it is important to establish that the pyroxenes are primary in addition our data suggest that experimental studies have underestimated solid liquid ds for rees in pigeonite and that ree contents of liquids calculated using these ds are overestimates our results have implications for sm nd age studies our work shows that if pigeonite inversion and or subsolidus reequilibration between augite and orthopyroxene occurred significantly after crystallization and if pyroxene separates isolated for sm nd studies do not have the bulk composition of the primary pyroxenes then the sm nd isochron age and end will be in error

petrology and geochemistry of lunar granite 12032 366 19 and implications for lunar granite petrogenesis apollo 12 sample 12032 366 19 is a 21 3 mg granite fragment that is distinct from any other lunar granite or felsite it is composed of barian k feldspar quartz sodic plagioclase hedenbergite fayalite and ilmenite with trace amounts of zirconolite baddeleyite apatite and merrillite the texture of 12032 366 19 is largely a micrographic intergrowth predominantly of k feldspar and quartz and to a lesser extent plagioclase and quartz hedenbergite fayalite and ilmenite are present in minor but significant quantities 6 0 3 1 and 1 7 wt respectively and are scattered throughout the feldspar quartz intergrowths trace amounts of zr bearing phases are found including zirconolite 0 6 wt and baddeleyite 0 04 wt incompatible trace element concentrations are high in 12032 366 19 particularly the high field strength elements e g zr sm and th 1500 25 and 61 g g respectively the chondrite normalized rare earth element concentrations form a v pattern that is characteristic of other lunar granitic material by modeling 12032 366 19 as a derivative from a kreep like parent melt the composition and mineral assemblage can be obtained by extended fractional crystallization combined with separation of the low density minerals plus trapped melt components prior to final solidification however this model cannot quantitatively account for the relatively sodic composition of the plagioclase an 34 50 and requires that the starting melt has na 2 o of 1 2 1 4 wt which is higher than most kreep compositions formation of this assemblage by silicate liquid immiscibility is neither required nor indicated by petrogenetic modeling

ion microprobe investigation of exsolved pyroxenes in cumulate encrites determination of selected trace element partition coefficients we have examined the partitioning of selected minor and trace elements in exsolved pyroxenes from cumulate eucrites by secondary ion mass spectrometry sims solid solid partition coefficients d s for al cr ti seven rees sr y and zr have been determined between low ca and high ca pyroxenes from moore county binda serra de mage and moama equilibrium temperatures of the co existing pyroxenes were calculated to constrain the relevant temperatures for the partition coefficients trace element abundance patterns are similar for pyroxenes from the four cumulate eucrites and thus indicate similar distribution behaviors of the trace elements during exsolution there is a significant hree enrichment over lrees in the low ca pyroxenes and abundances of the rees in augite are greater than those found in the low ca pyroxene hosts this ree behavior reflects the pyroxene crystal structures the calculated solid solid partition coefficients are found to vary systematically as expected from pyroxene crystal chemical arguments calculated subsolidus equilibration temperatures are within the expected range produced by pyroxene solvus temperature composition relations and consistent with petrographic observations of the cumulates the trace element patterns and abundances indicate that three of the four cumulates examined binda moama serra de mage were formed from the same melt or similar melts crystallizing under similar conditions in their parent body moore county has much higher trace element concentrations and this suggests that it either formed from a more evolved melt than the other three cumulates and crystallized later in the fractionation sequence or alternatively it was derived from a different melt system

a synthesis of the geologic evolution of taiwan abstract the island arc of taiwan is composed of cenozoic geosynclinal sediments more than 10 000 m thick lying on a pre tertiary metamorphic basement pleistocene to miocene andesitic islands surround the main island and are related mostly to arc magmatism the penghu island group in the taiwan strait is covered with pleistocene flood basalt neogene shallow marine clastic sediments are exposed mainly in the western foothills with pleistocene andesitic extrusives at the northern tip and the northeastern offshore islands a thick sequence of paleogene to miocene argillitic to slaty metaclastic rocks underlies the western central range and forms the immediate sedimentary cover on the pre tertiary metamorphic complex to the east which represents an older mesozoic arc trench system the coastal range in eastern taiwan is a neogene andesitic magmatic arc including also a large variety of volcaniclastic and turbiditic sediments cenozoic taiwan is the site of arc continent collision where the luzon arc on the philippine sea plate overrides the chinese continental margin on the eurasian plate east and northeast of taiwan the polarity of subduction changes whereby the oceanic philippine sea plate is subducting beneath the ryukyu arc system on the eurasian plate continent arc collision in taiwan island is anomalous and may occur in a broad belt of deformation rather than along a well defined plate boundary or subduction zone

a wet heterogeneous lunar interior lower mantle and core dynamo evolution while recent analyses of lunar samples indicate the moon had a core dynamo from at least 4 2 3 56 ga mantle convection models of the moon yield inadequate heat flux at the core mantle boundary to sustain thermal core convection for such a long time past investigations of lunar dynamos have focused on a generally homogeneous relatively dry moon while an initial compositionally stratified mantle is the expected consequence of a postaccretionary lunar magma ocean furthermore recent re examination of apollo samples and geophysical data suggests that the moon contains at least some regions with high water content using a finite element model we investigate the possible consequences of a heterogeneously wet compositionally stratified interior for the evolution of the moon we find that a postoverturn model of mantle cumulates could result in a core heat flux sufficiently high to sustain a dynamo through 2 5 ga and a maximum surface dipolar magnetic field strength of less than 1 t for a 350 km core and near 2 t for a 450 km core we find that if water was transported or retained preferentially in the deep interior it would have played a significant role in transporting heat out of the deep interior and reducing the lower mantle temperature thus water if enriched in the lower mantle could have influenced core dynamo timing by over 1 0 gyr and enhanced the vigor of a lunar core dynamo our results demonstrate the plausibility of a convective lunar core dynamo even beyond the period currently indicated by the apollo samples

chromite symplectites in mg suite troctolite 76535 as evidence for infiltration metasomatism of a lunar layered intrusion abstract despite the very low chromium concentrations in its cumulus olivine 140 ppm lunar troctolite 76535 contains large amounts of cr sporadically but highly concentrated in symplectite assemblages consisting of mg al chromite and two pyroxenes previously proposed symplectite formation mechanisms include crystallization of trapped interstitial melt diffusion of cr from cumulus olivine and or remobilization of cumulus chromite grains these mechanisms would imply that the highly cr depleted nature of mg suite parental magmas and their source materials inferred from cumulus olivine may be illusory we have conducted a detailed petrologic and textural study of symplectites as well as chromite veins intercumulus assemblages olivine hosted melt inclusions and clinopyroxene troilite veins in 76535 with the goals of constraining the origin of the symplectites and the degree of cr depletion in mg suite magmas relative to other lunar basalts orthopyroxene and clinopyroxene in melt inclusions are depleted in cr relative to their symplectite counterparts averaging 900 and 1200 ppm vs 7400 and 8100 ppm cr 2 o 3 respectively olivine in contact with symplectite assemblages may exhibit a diffusion profile of cr going into olivine whereas olivine boundaries away from symplectites show no diffusion profile there is also a distinct lack of primary chromite as inclusions in cumulus phases and melt inclusions multiple textural observations melt inclusion chemistry and modeling of chromite olivine equilibrium rule out previously proposed symplectite formation mechanisms and strongly suggest that chromite was not a primary crystallization product of the 76535 parental magma accordingly the post cumulus addition of cr and fe is required to produce the symplectites after considering multiple models the addition of cr and fe to 76535 via infiltration metasomatism by an exogenous chromite saturated melt is the model most consistent with multiple textural and geochemical observations failure of models that call upon cr diffusion out of olivine grains imply that the observed cr depleted nature of olivine observed in many mg suite lithologies is a primary feature of the cr depleted nature of the mg suite parental magmas and their source materials this substantial depletion of cr in the magma relative to mare basalt magmas still requires a satisfactory explanation in order to be consistent with mg suite petrogenetic models and currently accepted bulk moon compositions additionally if the intimate interaction of migrating melts with early lunar crustal lithologies was a widespread phenomenon after lmo solidification it provides another mechanism by which to reset or delay closure of radiogenic isotopic systems and explain the mg suite ferroan anorthosite age overlap

highly silicic compositions on the moon using data from the diviner lunar radiometer experiment we show that four regions of the moon previously described as red spots exhibit mid infrared spectra best explained by quartz silica rich glass or alkali feldspar these lithologies are consistent with evolved rocks similar to lunar granites in the apollo samples the spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar the variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the moon basaltic underplating is the preferred mechanism for silicic magma generation leading to the formation of extrusive landforms this mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies

orthopyroxene as a recorder of lunar crust evolution an ion microprobe investigation of mg suite norites the lunar mg suite which includes dunites troctolites and norites could make up 20 30 of the moon s crust down to a depth of 60 km the remainder is largely anorthositic this report focuses on norites because we have found that the chemical characteristics of orthopyroxene are effective recorders of their parental melt compositions many of the samples representing the mg suite are small and unrepresentative in addition they are cumulates and thus are difficult to study by whole rock techniques therefore we decided to study these rocks by sims techniques to analyze a suite of trace elements in orthopyroxene the 12 norite samples were selected from a recent compilation by warren who attempted to select the best candidate samples from the standpoint of their pristine character our present database includes greater than 300 superior electromagnetic pulse emp analyses and greater than 50 scanning ion mass spectroscopy sims analyses for 8 rare earth elements ree zr y and sr the mg s for the parental melts calculated from mg s in orthopyroxene show that most melts have mg s in the range of 0 36 0 60 this compares with a range of mg s for lunar volcanic picritic glass beads of 0 4 0 68 therefore although the cumulate whole rock compositions of the mg suite can be extremely magnesian the calculated parental melts are not anomalously high in mg a chemical characteristic of the mg suite norites that is more difficult to explain is the high kreep content of the calculated parental melts the ree contents for the calculated norite parental melts have ree that match or exceed the high k kreep component of warren therefore mixing of a kreep component and a picritic melt cannot by itself explain the high estimated ree contents of the melts parental to norites advanced crystallization following kreep incorporation especially of plagiclase may also be required

very high potassium vhk basalt complications in mare basalt petrogenesis apollo 14 vhk very high potassium basalt is a newly discovered variety of low ti high al mare basalt characterized by unusually high concentrations of k rb and ba and high ratios of these elements to other incompatible elements that exceed normal lunar values potassium feldspar and k si rich glass are ubiquitous and widespread components of these basalts other phases include magnesian olivine fo 60 73 fe rich olivine fo 31 50 pigeonite plagioclase an 79 95 ilmenite cr ulv spinel fe metal and troilite vhk basalts have low initial 87sr 86sr ratios with rb sr ratios estimated to be 15 higher than their source this rb sr fractionation occurred at their time of formation 3 75 aeons hypotheses involving volatile nonvolatile fractionations or long term enrichment of the source regions in k are inconsistent with the high ba la ratios and low initial 87sr 86sr ratios of vhk basalt the most plausible origin for these rocks is partial assimilation of lunar granite by a normal low ti high al mare basalt assimilation occurs by diffusion controlled exchange of alkalis and ba between two melts trace element compositions of the granitic melt are controlled in part by refractory accessory phases in the granite significant geochemical interaction between the lunar crust and mare basalts is implied

lunar mg suite thermobarometry and petrogenesis of parental magmas using compilations of internally consistent thermodynamic data on minerals and advances in quantifying the energetics of crystalline solid solutions we have recalculated the pressures and temperatures of equilibration of troctolite sample 76535 and a number of spinel cataclasites the five phase assemblage olivine orthopyroxene clinopyroxene cr spinel plagioclase which occurs in symplectite assemblages in 76535 gives equilibration temperatures from 800 900 c and pressures from 200 to 250 mpa indicating a deep 40 50 km crustal source spinel cataclasite assemblages give minimum pressures of 100 mpa mg suite magmas were apparently intruded throughout the lunar crust early in lunar history the textures and equilibration temperatures in many mg suite samples are consistent with sub solidus recrystallization and the mg rich minerals of some refractory troctolites and dunites may be residues of a crustal melting process or products of subsolidus elemental redistribution the sm nd age of 4 26 0 06 ga of troctolite 76535 most likely represents the time of sub solidus recrystallization and or partial melting in an attempt to identify the primary source material for the mg suite magmas a variety of models were tested using the melts and magfox codes a good fit between mineral compositions and crystallization sequences is obtained by 20 batch melting at 0 5 gpa of an average whole moon composition with an mg of 0 85 melts formed by batch melting at higher pressures and melts formed by poly baric partial fusion over the pressure range from 2 0 to 0 3 gpa were either too poor in mg and or crystallized clinopyroxene before orthopyroxene mixing with 10 20 urkreep which is required to satisfy the ree constraints of the mg suite reduces the mg of the parental magmas and requires a whole moon mg closer to that of the terrestrial mantle

the mairan domes silicic volcanic constructs on the moon 1 the mairan domes are four features located in northern oceanus procellarum at 312 3e 41 4n on the moon high resolution visible imagery visible to mid ir spectra and lunar prospector th abundance data all indicate that these four domes have a composition that is consistent with derivation from a si rich highly evolved magma

geomorphic analysis of the central range fault the second major active structure of the longitudinal valley suture eastern taiwan numerous landforms along the longitudinal valley suture of eastern taiwan indicate that two opposing reverse faults currently dominate the suturing process between the luzon volcanic arc and the central range of taiwan the east dipping longitudinal valley fault on the eastern flank of the valley is well known the west dipping central range reverse fault on the western flank of the valley is more obscure nonetheless it has produced many uplifted lateritic fluvial terraces along the eastern flank of the central range in the central reach of the valley from just north of the wuhe tableland to near chihshang the fault appears to be active but blind south of chihshang and inactive along the northern part of the longitudinal valley the late quaternary slip rate of the fault is less than 12 8 mm yr this constraint means that the fault is absorbing far less than half of the horizontal shortening across the longitudinal valley suture however the late quaternary slip rate along the fault may be comparable to the uplift and exhumation rate of the central range this suggests that localized brittle slip along the central range fault is an important component of crustal thickening and uplift of the range even though additional shortening and crustal thickening may be occurring because of pervasive deformation beneath the range

petrology and provenance of a very low titanium picrite clast in lunar highland regolith breccia 15295 clast 100 in regolith breccia 15295 could be a key to resolving the relationship s between mare basalts and lunar picritic glasses the clast is basaltic with texture mineralogy mineral compositions and calculated bulk composition suggesting that it crystallized in a thick lava flow or shallow intrusive body from a very low titanium vlt basaltic magma the estimated bulk composition of clast 15295 100 is primitive i e magnesian compared to those of known vlt basalts and is very close to those of vlt picritic green glasses especially the apollo 14 a green glass from these similarities we infer that clast 15295 100 is a crystalline product of a picritic magma similar to the apollo 14 a glass clementine and m3 remotely sensed data of the lunar surface were used to find areas that have chemical compositions consistent with those of clast 15295 100 not only near the apollo 15 site but in a broad region surrounding the site two regions are consistent with clast s 15295 100 compositional data the larger region is in southern mare imbrium and a smaller region is in the eastern half of sinus aestuum these locations should be considered as candidates for future missions focusing on sample science

the origin of boninites on mercury an experimental study of the northern volcanic plains lavas abstract phase equilibrium experiments were conducted on a synthetic rock composition matching that of the northern volcanic plains of mercury as measured by the mercury surface space environment geochemistry and ranging spacecraft messenger the northern volcanic plains are smooth plains of suspected volcanic origin that cover more than 6 of the surface area of mercury the northern volcanic plains are less cratered than their surroundings and reported to be the product of flood volcanism making them a prime candidate for experimental study the bulk composition of the northern volcanic plains is that of an alkali rich boninite and represents the first silica enriched crustal terrane identified on an extraterrestrial planet from orbital data phase equilibrium experiments were conducted over the pressure range of the mercurian mantle 0 5 5 gpa at very low oxygen fugacity iw0 to 7 using a piston cylinder apparatus p 0 5 1 7 gpa and a walker style multi anvil device p 2 5 gpa our results indicate the origin of the northern volcanic plains lavas boninites are best explained by high degrees of partial melting of an olivine dominant pyroxene and plagioclase bearing mantle source at low pressure 1 4 gpa and does not require hydrous melting to achieve the silica enriched melt composition the formation mechanism for boninites on mercury contrasts substantially with terrestrial boninites which typically occur in oxidized and hydrous arc environments associated with subduction zones instead mercurian boninites form at exceptionally low oxygen fugacity and do not require melting of hydrated source materials the nvp lavas represent a novel mechanism by which planetary bodies can form silica enriched secondary crusts without the aid of water

petrography geochronology and source terrain characteristics of lunar meteorites dhofar 925 961 and sayh al uhaymir 449 abstract dhofar dho 925 961 and sayh al uhaymir sau 449 are brecciated lunar meteorites consisting of mineral fragments and clasts from a range of precursor lithologies including magnesian anorthositic gabbronorite granulites crystalline impact melt breccias clast bearing glassy impact melt breccias lithic fragmental breccias mare basalts and evolved silica rich rocks on the similarity of clast type and mineral chemistry the samples are likely grouped and were part of the same parent meteorite phosphate pb pb ages in impact melt breccias and matrix grains demonstrate that dho 961 records geological events spanning 500 ma between 4 35 and 3 89 ga these pb pb ages are similar to the ages of ancient intrusive magmatic samples and impact basin melt products collected on the lunar nearside by the apollo missions however the samples bulk rock composition is chemically distinct from these types of samples and it has been suggested that they may have originated from the farside south pole aitken impact basin i e jolliff et al 2008 we test this hypothesis and conclude that although it is possible that the samples may be from the south pole aitken basin there are other regions on the moon that may have also sourced these complex breccias

the materials of the lunar procellarum kreep terrane a synthesis of data from geomorphological mapping remote sensing and sample analyses major features of the moon s procellarum kreep terrane include subdued relief and extensive resurfacing with mare basalt consistent with high concentrations of th and other heat producing elements at depth we relate the chemistry of sampled materials to the geomorphology th surface concentrations determined by the lunar prospector 2 pixels and feo and tio2 concentrations derived from clementine ultraviolet visible spectral data on the basis of geologic maps each pixel was classified as mare terra or mixed near the periphery of the terrane terra pixel compositions are relatively feldspathic in the interior they mainly represent imbrium basin rim or ejecta deposits and are mainly incompatible trace element rich norites and presumably represent materials from a thick section tens of kilometers of the pre imbrium crust of the terrane excavated by the imbrium event although imbrium ejecta are the principal source of surface terra materials the imbrium event did not create the th rich procellarum kreep terrane broad continuous expanses of mare pixels are observed with little interruption from protruding terra or terra penetrating craters the mare basalt dominated regoliths of these areas have a wide range of tio2 concentrations 18 leading to the conclusion that the high th concentrations are in the mare basalts and are not present in the regoliths as terra derived materials volcanic glasses and impact glasses of mare basalt composition collected from the procellarum kreep terrane support this conclusion

lunar ferroan anorthosite petrogenesis clues from trace element distributions in fan subgroups the rare earth elements ree and selected other trace elements were measured in plagioclase and pyroxene from nine samples of the lunar ferroan anorthosite fan suite of rocks samples were selected from each of four fan subgroups previously defined by james et al 1989 plagioclase compositions are homogeneous within each sample but high and low ca pyroxenes from lithic clasts typically have different ree abundances from their counterparts in the surrounding granulated matrices measured plagioclase low ca pyroxene concentration ratios for the ree have steeper patterns than experimentally determined plagioclase low ca pyroxene partition coefficients in most samples textural and trace element evidence suggest that although subsolidus equilibration may be responsible for some of the discrepancy plagioclase compositions in most samples have been largely unaffected by intermineral redistribution of the ree the ree systematics of plagioclase from the four subgroups are broadly consistent with their derivation through crystallization from a single evolving magma however samples from some of the subgroups exhibit a decoupling of plagioclase and pyroxene compositions that probably reflects the complexities inherent in crystallization from a large scale magmatic system for example two anorthosites with very magnesian mafic minerals have highly evolved trace element compositions major element compositions in plagioclase also do not reflect the evolutionary sequence recorded by their ree compositions finally a noritic anorthosite breccia with relatively ferroan mafic minerals contains several clasts with high and variable ree and other trace element abundances although plagioclase ree compositions are consistent with their derivation from a magma with a kreepy trace element signature very shallow ree patterns in the pyroxenes suggest the addition of a component enriched in the light ree

thermal and magmatic evolution of the moon as with all science our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data this process invigorates the intellectual foundation on which old models are tested and new concepts are built just as the application of new observational tools to lunar science in 1610 galileo s telescope and 1840 photography yielded breakthroughs concerning the true nature of the lunar surface the computational and technological advances highlighted by the apollo and post apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the moon 1 1 pre apollo view of the thermal and magmatic evolution of the moon many of the early views of the moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the sun and the moon prophetically myths involving the lunar deities mwuetsi from zimbabwe and coyolxauhqui from mexico told of rather violent or catastrophic events in which the moon was expunged from the earth numerous ancient scientific observations were made about the nature of the moon ranging from those uncovered in early neolithic sites that correctly identified mare crisium and mare humorum to the insights made by greek philosophers such as anaxagoras ca 500 428 b c and democritus ca 460 370 b c who attached terrestrial analogues to its character stone mountains with the advent of the telescope 1610 and photography 1840 as scientific tools for lunar exploration semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation initially modern terrestrial geological analogs were extended to the moon lunar highlands volcanic craters seas combined with the rigors of computational modeling these observational data were extended to predict the original thermal state of the moon and its thermal and magmatic history its proximity to the earth

experimental analysis of crack propagation in granite an experimental approach is used to demonstrate the concept of an effective crack length with double edge notched specimens of charcoal and rockville granite crack propagation in rock is characterized by microcracking around the crack tip and interlocking along a portion of the crack this region is called the fracture process zone and together with the traction free length defines the effective crack length twenty closed loop strain controlled fracture tests were conducted on charcoal and rockville granite crack growth was monitored with a travelling optical microscope 100 x magnification by comparing the post peak behaviour of both granites it is suggested that the process zone is larger for the larger grain sized rock rockville conventional linear elastic fracture mechanics techniques are used to calculate the apparent fracture toughness of charcoal granite at various crack lengths in addition a j integral expression is derived for the double edged notched geometry in terms of the area under the load displacement record the shortcomings of both analyses are discussed an attempt is made to explain the inadequacies by including the process zone in the calculations of the fracture toughness author trrl

megaregolith insulation and the duration of cooling to isotopic closure within differentiated asteroids and the moon ages determined for extraterrestrial samples by the sm nd and rb sr techniques are commonly assumed to record igneous crystallization events because in solid silicates nd and sr diffuse at exceedingly slow rates however we find that for coarse grained igneous cumulate rocks from the moon or from a large thoroughly brecciated asteroid this assumption may not be reliable the moon and at least one asteroid the parent body of the eucrite diogenite and howardite meteorites appear to have been largely molten at or about the time they formed we have modeled global cooling of the moon and large r 40 250 km asteroids starting at or near the solidus a crucial factor in determining the prevailing interval ic of cooling between igenous crystallization and isotopic closure for any given depth in the crust is the extent to which the body is insulated by a regolith megaregolith layer of porous fragmental impact debris given plausible assumptions regarding the thicknesses of such layers on the moon and the eucrite parent asteroid and regarding the radius of the eucrite asteroid our results indicate that deep crustal regions tend to remain above the nd and sr isotopic closure temperature for intervals that are long in comparison to the precision of modern nd and sr based age measurements and in comparison to suggested chronologic scenarios of global differentiation ic intervals of as long as 100 m y may be common among available samples of primordial deep crustal cumulates from both bodies chronologies for the gross solidification of the moon and the eucrite asteroid should allow for the possibility that any single age for a coarse grained plutonic or cumulate textured rock might be many tens of millions of years younger than the igneous crystallization age

very high k kreep rich clasts in the impact melt breccia of the lunar meteorite sau 169 new constraints on the last residue of the lunar magma ocean abstract in the impact melt breccia imb of sayh al uhaymir sau 169 the most kreep rich lunar meteorite to date gnos et al 2004 clasts of a new type of lithologies were discovered consisting of ca poor and ca rich pyroxenes 60 8 vol ba rich k feldspar 27 9 vol phosphates 5 6 vol nb rich ilmenite 4 0 vol zircon 1 2 vol and minor sulfide 0 6 vol these mafic lithic clasts are more enriched in kreep component 1500 ci than the host meteorite and are highly enriched in potassium they are referred to as very high k vhk kreep lithology and probably most close to the last residual liquid of the lunar magma ocean without significant dilution by other mg rich magmas the fine grained matrix of the sau 169 imb has very similar mineral chemistry to the vhk kreep lithology but contains abundant plagioclase with trace k feldspar the matrix shows decoupling of k from the reep like component however it cannot be simply interpreted by mixing the vhk kreep lithology with anorthosites which should have diluted the reep like component with the same proportion sims pb pb dating was conducted on zircons in various petrographic settings and with different crystal habits all analyses show a main age peak at 3921 3 ma and a smaller one at 4016 6 ma the main age peak is identical to the previous pb pb age by gnos et al 2006 and u pb age by liu et al 2009 dating the catastrophic shock event contributed to the formation of sau 169 imb the older ages are consistent with the previous report of an older bulk u pb age by kramers et al 2007 suggestive of presence of relict crystals in a few large zircon grains the vhk kreep clasts predated the fine grained matrix but have the same zircon pb pb ages as the latter within the analytical uncertainties plagioclase was converted to maskelynite whereas zircon was shocked to diaplectic glass probably by a second event at 2 8 ga however the identical zircon pb pb ages of the amorphous parts and the remained crystalline areas indicate no resetting of pb pb isotopes by the later shock metamorphism or there was another severe impact event postdated solidification of the fine grained matrix within a few million years

northwest africa 773 lunar origin and iron enrichment trend the meteorite northwest africa 773 nwa 773 is a lunar sample with implications for the evolution of mafic magmas on the moon a combination of key parameters including whole rock oxygen isotopic composition fe mn ratios in mafic silicates noble gas concentrations a kreep like rare earth element pattern and the presence of regolith agglutinate fragments indicate a lunar origin for nwa 773 partial maskelynitization of feldspar and occasional twinning of pyroxene are attributed to shock deformation terrestrial weathering has caused fracturing and precipitation of carich carbonates and sulfates in the fractures but lunar minerals appear fresh and unoxidized the meteorite is composed of two distinct lithologies a two pyroxene olivine gabbro with cumulate texture and a polymict fragmental regolith breccia the olivine gabbro is dominated by cumulate olivine with pigeonite augite and interstitial plagioclase feldspar the breccia consists of several types of clasts but is dominated by clasts from the gabbro and more feo rich derivatives variations in clast mineral assemblage and pyroxene mg mg fe and ti ti cr record an igneous fe enrichment trend that culminated in crystallization of fayalite silica hedenbergitebearing symplectites the fe enrichment trend and cumulate textures observed in nwa 773 are similar to features of terrestrial ponded lava flows and shallow level mafic intrusives indicating that nwa 773 may be from a layered mafic intrusion or a thick differentiated lava flow nwa 773 and several other mafic lunar meteorites have lree enriched patters distinct from apollo and luna mare basalts which tend to be lree depleted this is somewhat surprising in light of remote sensing data that indicates that the apollo and luna missions sampled a portion of the moon that was enriched in incompatible heatproducing elements

the fracture process zone in granite evidence and effect abstract evidence of the fracture process zone and its effect on fracture toughness were examined for charcoal and rockville granite average grain sizes of 1 and 10mm fracture tests were conducted on wedge loaded double cantilever beam specimens 500 mm long 200 mm wide 40 mm thick the seismic techniques of ultrasonic probing and acoustic emission were utilized to measure the inelastic region the beginning of the process zone was interpreted by a three fold increase in transmission of ultrasound from an open crack to a partially closed crack the end of the damage zone was found by comparing surface wave amplitudes before and after fracture following these procedures the inelastic region in charcoal granite was about 40 mm whereas in rockville granite a region over 90 mm long was estimated the major acoustic activity was located within the macrocrack being released from unbroken or interlocked crystals the experimental evidence indicated an effective crack to be composed of a traction free length and a ligament process zone which was observed to form a single multiconnected region within the macrocrack the effective crack was used for an r curve calculation so that the energy consumed in the process zone was included in an approximate manner by elongating the crack length a model of crack propagation in rock consistent with measurements of the inelastic region describes the effect of a process zone on fracture toughness testing

chronology and petrogenesis of the lunar highlands alkali suite cumulates from kreep basalt crystallization alkalic rocks from the highlands of the moon though relatively minor in volume yield important information in understanding the later development of the lunar crust however until recently little information has been available on the crystallization ages of samples from this diverse suite of rocks previous workers suggested a link between pristine kreep basalts and lunar quartz monzodiorites and granites through mineral and chemical modelling of all known pristine highlands alkali suite has rocks and radiogenic isotopic analyses of rather large has clasts from the apollo 14 landing site we explore further this potential link two clasts of alkalic affinity from the western highlands of the moon have been analyzed for their neodymium and strontium isotopic compositions an alkali anorthosite 14304 267 yields a smnd mineral isochron of 4108 53 ma mswd 0 06 and an end t of 1 0 0 2 two splits of the same alkali norite clast 14304 270 and 14304 272 yield similar end values when calculated for this age rbsr systematics for alkali anorthosite 14304 267 scatter about a line which yields an age of 4336 81 ma however the large mean square of weighted deviates mswd for this line 12 3 indicates that the age is suspect and that rbsr sytematics may have been disturbed the smnd age for 14304 267 in conjunction with upb zircon ages for two other highlands alkali suite has rocks from the apollo 14 landing site and one from the apollo 16 landing site indicate production of has rocks over an extended time period spanning at least 300 million years from 4 34 to 4 02 ga since the last dregs of the lunar magma ocean lmo likely crystallized prior to 4 3 ma all rocks from this alkalic period cannot represent direct remnants of the late lmo and may include material resulting from the remelting of evolved portions of the moon by upward moving basaltic melts from the deep lunar interior these contaminated melts may be represented by pristine kreep basalts from the apollo 15 landing site these kreep basalt melts could have crystallized within the crust to form cumulate gabbros norites anorthosites monzodiorites and possibly granites with the proportion of trapped kreepy residual liquid determining the large ion lithophile element enrichment of the rock generally the proportion of trapped kreepy liquid is small 2 15 the broad age range for the lunar has indicates that parental kreep basalt magmatism was not a unique event but was an important process possibly repeated several times throughout the first 600 to 700 million years of lunar history

coseismic versus interseismic ground deformations fault rupture inversion and segmentation revealed by 2003 mw 6 8 chengkung earthquake in eastern taiwan 1 the 2003 chengkung earthquake mw 6 8 provided diagnostic evidence for a source model showing the deformation process of the seismogenic chihshang fault in eastern taiwan the aftershocks show a fault bend at a depth of 18 km coseismic ground displacements recorded by strong motion records allow us to deduce instant rupturing of this event our resulting model shows a fault length of 33 km and dip slip dominant rupture on fault plane deeper than 18 km estimated coseismic displacements constrain two fault planes one at 5 18 km depth dipping 60 e and 18 36 km depth dipping 45 e the uppermost fault plane of the chihshang fault 0 5 km did not break immediately after the main shock however it may have a major role in after slip and even interseismic ground deformation the taiyuan basin developed in the hanging wall is a geomorphic feature consistent with and adequately explained by coseismic ground displacements

evidence for precollisional subduction erosion in ancient collisional belts the case of the mid european variscides analysis of the fore arc remnants and suture zone rocks in the european variscides using criteria established for the circum pacific margins geometry sedimentary evolution and style of deformation shows that precollisonal orogenic evolution can also be reconstructed for ancient collisional belts the collision zone of the lower plate thrust belt rhenohercynian zone and the upper plate arc and fore arc remnants saxothuringian zone and saar basin indicate subduction erosion of the upper plate by some 50 km length of upper plate lithosphere prior to collision removal started during early convergence in the famennian ca 365 ma and lasted until the late visean onset of collision ca 330 ma part of this material may have been underplated below the upper plate and has since resurfaced as high pressure rocks contributing to the metamorphic core of the orogen

stratigraphy of the lunar highland crust depths of burial of lunar samples from cooling rate studies current models of lunar crustal stratigraphy are based primarily on models of impact cratering coupled with what is known about the distribution of rock types in the ejecta blankets associated with the large multiring basins these models postulate an upper crust rich in the ferroan anorthosite component underlain by a more mafic noritic lower crust spudis 1993 we attempted to test these models by determining the depth at which various lunar plutonic rocks formed despite intense brecciation and shock many lunar highland samples retain vestiges of a prior magmatic history for example pyroxene samples preserve a record of their thermal history in such phenomena as cation ordering and exsolution textures by computer simulation of the growth of exsolution lamellae in augite and pigeonite we deduced cooling rates and from these estimated a depth of burial on the basis of a simple model for the thermal evolution of the lunar crust despite the fairly large uncertainties in the calculations it is clear that the ferroan anorthosite samples we studied formed at a depth between 10 and 20 km whereas some members of highland magnesian and alkali suites formed as cumulates in magma chambers intruded into the uppermost layers of the crust as yet there is no evidence to indicate that crystalline rocks from the lower half of the lunar crust are present in the samples returned by the apollo missions most samples derived from the lower crust appear to be impact melts oflow k fra mauro noritic composition

mid infrared spectroscopy of impactites from the nordlinger ries impact crater abstract this study is part of an effort to build a mid infrared database 7 14 m of spectra for mertis mercury radiometer and thermal infrared spectrometer an instrument onboard of the esa jaxa bepicolombo space probe to be launched to mercury in 2017 mercury was exposed to abundant impacts throughout its history this study of terrestrial impactites can provide estimates of the effects of shock metamorphism on the mid infrared spectral properties of planetary materials in this study we focus on the nordlinger ries crater in southern germany a well preserved and easily accessible impact crater with abundant suevite impactites suevite and melt glass bulk samples from otting and aumuhle as well as red suevite from polsingen were characterized and their reflectance spectra in mid infrared range obtained in addition in situ mid infrared spectra were made from glasses and matrix areas in thin sections the results show similar but distinguishable spectra for both bulk suevite and melt glass samples as well as in situ measurements impact melt glass from aumuhle and otting have spectra dominated by a reststrahlen band at 9 3 9 6 m bulk melt rock from polsingen and bulk suevite and fine grained matrix have their strongest band between 9 4 and 9 6 m there are also features between 8 5 and 9 m and 12 5 12 8 m associated with crystalline phases there is evidence of weathering products in the fine grained matrix such as smectites mercury endured many impacts with impactors of all sizes over its history so spectral characteristics observed for impactites formed only in a single impact like in the ries impact event can be expected to be very common on planetary bodies exposed to many more impacts in their past we conclude that in mid infrared remote sensing data the surface of mercury can be expected to be dominated by features of amorphous materials

clinopyroxene ree distribution coefficients for shergottites the ree content of the shergotty melt abstract ree distribution coefficients were measured between synthetic pyroxenes and melts similar in composition to the inferred shergotty intercumulus liquid by in situ analysis with the electron microprobe using samples doped to per cent concentration levels these coefficients exhibit a strong positive correlation with pyroxene wollastonite content recommended values for augites similar in composition to the shergotty cumulus augite cores wo32en48 are d la 0 023 d ce 0 039 d nd 0 10 d sm 0 17 d eu 0 16 d gd 0 20 d yb 0 29 and d lu 0 30 recommended values for pigeonites similar in composition to the shergotty cumulus pigeonite cores wo12en58 are d la 0 002 d ce 0 004 d nd 0 019 d sm 0 031 d yb 0 13 and d lu 0 13 these values resemble distribution coefficients measured for terrestrial basalts of higher mg fe than the shergotty melt rather than those of more evolved siliceous rocks of similar mg fe to the shergotty melt thus it appears that mg fe is considerably less important than other factors in determining distribution coefficient values for pyroxenes ree abundances were computed for the shergotty intercumulus melt using distribution coefficients measured for the natural phase compositions these computed abundances display lree depletion such lree depleted abundance patterns cannot be generated by simple partial melting of a mafic mineral assemblage having the lree enriched patterns required for a two stage sm nd evolution history this result implies that either 1 the melting process was complex e g continuous melting 2 the source region had a more complex history than that of the simple 2 stage model or 3 shergotty does not satisfy the closed system assumption of the calculation and has suffered post magmatic lree enrichment

the hadley apennine kreep basalt igneous province abstract we have studied 27 kreep basalt fragments in six thin sections of samples collected from four apollo 15 stations based on local geology and regional remote sensing data these samples represent kreep basalt lava flows that lie beneath the younger local apollo 15 mare basalts and under other mare flows north of the apollo 15 site some of these rocks were deposited at the site as ejecta from the large craters aristillus and autolycus kreep basalts in this igneous province have a volume of 103 2 104 km3 mineral and bulk compositional data indicate that the erupted magmas had mg 100 molar mg mg fe up to 73 corresponding to orthopyroxene rich interior source regions with mg up to 90 minor element variations in the parent magmas of the kreep basalts inferred from compositions of the most magnesian pyroxene and most calcic plagioclase in each sample indicate small but significant differences in the concentrations of minor elements and mg reflecting variations in the composition of lower crustal or mantle source regions and or different amounts of partial melting of those source regions

origin of lunar very high potassium vhk basalts a combination of endogenous and exogenous processes abstract very high potassium or vhk basalts have been described from the apollo 14 landing site at fra mauro on the lunar near side many of the known samples are clasts in polymict breccias with a few as new work completed on fourteen vhk basalts include crystal size distributions csds and in situ chemical analyses and element maps collected by electron probe microanalysis epma csds completed on three vhk basalt samples indicate that these basalts are not impact melts and represent endogenous melts of the lunar interior potassium k element maps reveal the spatial relationship between the k rich material and the basalt clasts with attached breccia matrix if present in situ epma analyses have identified two distinct types of k rich material k feldspar and k rich glass with these new data an additional mechanism for an exogenic petrogenesis of vhk basalts is proposed that involves the impact process vhk basalts can be divided into two groups based on density and viscosity vhk 1 basalts formed when a hot impact ejecta covered the granite felsite rich matrix material containing high al basalt clasts heat from the impact ejecta partially melted and possibly evaporated nearby k bearing materials which then infiltrated and contaminated the high al clasts vhk 2 basalts are consistent with the hypothesis of granite assimilation by a high al magma as seen in the higher abundances of network forming elements

potential effects of subglacial water pressure fluctuations on quarrying water pressure fluctuations beneath glaciers may accelerate rock fracture by redistributing stresses on subglacial bedrock and changing the pressure of water in bedrock cracks to study the potential influence of water pressure fluctuations on the fracture of subglacial bedrock ice flow over a small bedrock step with a water filled cavity in its lee is numerically modeled and stresses on the bedrock surface are calculated as a function of transient water pressures in the cavity stresses on the bed are then used to calculate principal stress differences within the step rapid reductions in cavity water pressure increase principal stress differences in the bed increasing the likelihood of crack growth in the step and the formation of predominantly vertical fractures relatively impermeable bedrock may be most susceptible to fracturing during water pressure reductions because high water pressure in cracks within the rock can be maintained as water pressure decreases in cavities these results when considered in conjunction with the strong likelihood that increases in water pressure accelerate the removal of rock fragments loosened from the bed suggest that in zones of ice bed separation where water pressure fluctuations typically are large rates of quarrying may be higher than along other parts of glacier beds