impact melt rocks from the ries structure germany an origin as impact melt flows abstract the production of impact melt rocks and glasses is a characteristic feature of hypervelocity impact events on earth and other planetary bodies this investigation represents the first detailed study of an unusual series of coherent impact melt rocks intermittently exposed around the periphery of the 24 km diameter 14 5 ma ries impact structure germany optical and analytical scanning electron microscopy sem reveals that the groundmass comprises sanidine plagioclase quartz and ilmenite decreasing order of abundance with the interstices filled by either fresh or devitrified glassy mesostasis primary crystallites display skeletal dendritic and or spherulitic textures indicating rapid crystallization from a melt the mesostasis is characterized by extreme chemical heterogeneity e g feo and al 2 o 3 contents from 1 to 62 80 wt this is likely due to a combination of crystal liquid fractionation during rapid cooling and crystallization of an originally incompletely homogenized melt vapor phase crystallization of sanidine and cristobalite occurred in miarolitic cavities during late stage cooling of the impact melts the most likely protolith for the impact melt rocks are granitic rocks present in the crystalline basement target the high volatile content of the mesostasis suggests that a large volatile component was retained from this protolith field observations together with analytical data and micro textures indicate that the ries impact melt rocks were molten at the time of and after deposition field relations with other impactites also suggest that these rocks were emplaced subsequent to the excavation stage of crater formation and that they are not therefore ballistic ejecta thus it is proposed that the ries impact melt rocks were emplaced as ground hugging impact melt flows that emanated from different regions of the evolving transient cavity during the modification stage of crater formation this is consistent with and in fact predicted by field relations which indicate that these rocks overlie unequivocal ejecta this represents the first recognition of impact melt flows near the rim of a terrestrial impact structure and is consistent with observations of such features on the moon and venus

geology and petrology of enormous volumes of impact melt on the moon a case study of the orientale basin impact melt sea abstract lunar basin forming impacts produce enormous volumes 10 5 km 3 of impact melt all known basin forming impacts combined may produce 10 8 km 3 of impact melt 1 20th the volume of the lunar crust despite their volumetric importance the geology and petrology of massive deposits of impact melt on the moon have been little studied in part because most basin impact melt deposits are old and have been obscured or buried by subsequent impact cratering and mare infill we investigate the geology and model the petrology of fresh massive impact melt deposits in the relatively young 930 km diameter orientale basin models of impact melt production combined with geologic analyses based on new lola topographic data suggest that most of the impact melt 2 3 produced by the orientale forming impact occurs in a 15 km thick impact melt sheet better described as an impact melt sea 350 km in diameter with a volume of 10 6 km 3 we anticipate that the orientale melt sea has undergone large scale igneous differentiation since terrestrial impact melt sheets such as manicouagan sudbury and morokweng less than a tenth of the thickness and a hundredth of the volume of the orientale melt sea have differentiated we develop a model for the cumulate stratigraphy of the solidified orientale impact melt sea a modeled cumulate stratigraphy occurring below a quench crust and anorthositic fallback breccia with an 8 km thick layer of norite overlying a 4 km layer of pyroxenite and a basal 2 km thick layer of dunite produced by equilibrium crystallization of a homogenized melt sea consistent with vigorous convection in that melt sea is supported by remotely sensed norite excavated by the central peak of maunder crater from 4 km depth generally we predict that very large basin forming impacts including the south pole aitken spa basin forming impact produce melt seas with a cumulate stratigraphy similar to that of the orientale melt sea impact melt differentiation may explain apparently anomalous lithologies excavated in the spa basin interior we note that impact melt differentiates are slow cooled the orientale melt sea took on the order of 10 5 years to solidify and if meteoritic siderophiles fractionate into metal or sulfide layers may not be siderophile enriched therefore impact melt differentiates may pass for pristine highland plutonic rocks in the lunar sample suite these predictions can be tested with current and future mission data

planetary surface dating from crater size frequency distribution measurements partial resurfacing events and statistical age uncertainty abstract we describe the procedure to fit a cumulative production function polynomial to a partial crater size frequency distribution the technique is of particular use in deriving ages for surfaces which have undergone partial resurfacing events namely erosional or depositional events which have affected a limited diameter range of the crater population we demonstrate its use in obtaining times for both the surface formation and the resurfacing event we give a practical outline of the method for making age measurements from crater counts and how to identify resurfacing effects in the results we discuss the conversion of production function polynomials between common presentations and the statistical uncertainty of the determined ages with respect to the non linear chronology function and a minor refinement of data binning

discoveries on the lithology of lunar crater central peaks by selene spectral profiler 1 the spectral profiler sp onboard the japanese selene kaguya spacecraft is now providing global high spectral resolution visible near infrared continuous reflectance spectra of the moon the reflectance spectra of impact craters on the farside of the moon reveal lithologies that were not previously identified the achievements of sp so far include the most definite detection of crystalline iron bearing plagioclase with its characteristic 1 3 m absorption band on the moon a new interpretation of the lithology of tsiolkovsky crater central peaks previously classified as olivine rich as mixtures of plagioclase and pyroxene and the lower limit of mg number of low ca pyroxene found at antoniadi crater central peak and peak ring which were estimated through direct comparison with laboratory spectra of natural and synthetic pyroxene samples

large scale seismically induced mass movements in a former glacial lake basin lake temiscouata northeastern appalachians eastern canada abstract disturbed lacustrine deposits of eastern canada have been associated with past seismic events in the intraplate western quebec seismic zone wqz and the charlevoix kamouraska seismic zone cksz with five major earthquakes that occurred during historical times and hundreds of minor earthquakes the cksz is the most active seismic zone in eastern canada here we present new high resolution multibeam bathymetric subbottom profiler and sediment core data collected in lake temiscouata southeastern quebec the largest lake located within the influence of the cksz the occurrence of mass movements in the highly cohesive glaciolacustrine deposits of the lake produced a peculiar lacustrine landscape consisting of steep slide scars and residual mounds and very narrow residual crests our data indicate that postglacial times were marked by recurrent seismically induced mass movement events that cannot be individually identified in the sedimentary record due to the highly disturbed stratigraphy of the lake and to the absence of significant postglacial background sediments between events the most recent recorded mass movement is a distinct debris flow sediment layer on the lake floor that was deposited at 1300 cal bp very shortly after a distinct large scale mass movement event observed across the entire lake basin the presence of silt layers in gyttja overlying these disturbed units suggests that the region was affected by other seismic events following this event although no mmds could be directly related to these layers

submarine canyons and channels in the lower st lawrence estuary eastern canada morphology classification and recent sediment dynamics abstract series of submarine canyons and channels observed in the lower st lawrence estuary lsle provide an opportunity to analyze in great detail the morphology spatial distribution and modern activity of such systems in a relatively shallow 300 m semi enclosed basin based on their geomorphology and physical settings the canyons and channels were classified into four categories according to their feeding sources ancient or recent glacially fed river fed longshore drift fed and sediment starved systems their activity was interpreted based on geomorphological characteristics such as the presence of bedforms related to gravity flows backscatter intensity axial incision and the presence of rapidly deposited layers in surficial sediments river fed deltas were interpreted as inactive mainly because suspended sediment concentrations at river mouths are low preventing the generation of hyperpycnal currents or delta lip failures related to high sediment supply longshore drift fed canyons present where the coastal shelf narrows were found to be episodically active probably due to earthquakes or extreme storm events unlike other longshore drift fed canyons observed elsewhere in the world they are active infrequently because of the modern low rates of sediment supply to their heads the most active canyons are the sediment starved type and were observed near pointe des monts their activity is probably due to slope failures and to the presence of strong hydrodynamic processes therefore sediment supply is not the main mechanism responsible for modern canyon and channel activity in the lsle however sediment supply has been an important factor during the formation of the submarine channels and canyons their quasi exclusive occurrence on the quebec north shore is attributed to its larger watershed and important sedimentary delivery during deglaciation the quebec north shore watershed is 20 times greater than the quebec south shore watershed which favored the transport of greater volumes of sediment during the early holocene moreover the slope proximity to the shore led to the formation of longshore drift fed systems on the north shore when sediment supplied to rivers were transferred on a narrow shelf

lunar central peak mineralogy and iron content using the kaguya multiband imager reassessment of the compositional structure of the lunar crust ryder and wood 1977 suggested that the lunar crust becomes more mafic with depth because the impact melts associated with the large imbrium and serenitatis basins are more mafic than the surface composition of the moon in this study we reexamine the hypothesis that the crust becomes more mafic with depth we analyze the composition of crater central peaks by using recent remote sensing data and combining the best practices of previous studies we compute the mineralogy for 34 central peaks using 1 nine band visible and near infrared data from the kaguya multiband imager 2 an improved version of hapke s radiative transfer model validated with spectra of lunar soils with well known modal mineralogy and 3 new crustal thickness models from the gravity recovery and interior laboratory data to examine the variation in composition with depth we find that there is no increase in mafic mineral abundances with proximity to the crust mantle boundary or with depth from the current lunar surface and therefore that the crust does not become more mafic with depth we find that anorthosite with very low mafic abundance purest anorthosite or pan is a minority constituent in these peaks and there is no clear evidence of a distinct pan rich layer in the middle crust as previously proposed the composition of most of the central peaks we analyze is more mafic than classically defined anorthosites with an average noritic anorthosite composition similar to that of the lunar surface

late quaternary morpho sedimentology and submarine mass movements of the betsiamites area lower st lawrence estuary quebec canada abstract a complex submarine geomorphology was revealed from multibeam bathymetry and seismic reflection surveys conducted between 2001 and 2007 in the lower st lawrence estuary offshore betsiamites river quebec canada in this paper we describe the submarine morpho sedimentology of an area of 500 km 2 with focus on the consequences of four mass movement events the general morpho sedimentology of the area and submarine features resulting from mass movement processes channel erosion and gas seepage are described a spatio temporal sequence for the occurrence of the mass movements and a chronology for the failures are established we propose dates for four of the observed mass movement deposits a buried paraglacial debris flow deposit is dated as older than 9280 cal bp whereas a major landslide scar characterized by two topographic depressions on the shelf and a sediment lobe in the laurentian channel were dated around 7250 cal bp morphological observations and sediment core analyses allow us to identify a least two different recent i e less than 500 yr old debris flow accumulations associated with two recent earthquakes 1 the ad 1663 m 7 and 2 ad 1860 m 6 or ad 1870 m 6 5 earthquakes in addition to a complex geomorphology influenced by mass movements we have identified several regions on the shelf and on the laurentian channel with evidence of pockmarks which could potentially influence submarine slope stability in the estuary

forced regressions and lowstand deltas holocene canadian examples abstract some canadian holocene deltas that formed during and after relative sea level falls of over 100 m are modern examples of forced regressions and lowstand deltas the principal controls on deltaic morphology and stratigraphy are rate of sea level change sediment supply timing type basin physiography and sediment dispersal processes in the receiving basin our observations indicate important alongstrike variability in deposition and erosion that affect facies architecture and stratal geometry during rapid relative sea level fall fluvial channels incise rapidly and do not migrate lateral channel migration which would produce a widespread fluvial unconformity begins once relative sea level fall has slowed and continues through the early part of relative sea level rise parts of he emerging shoreline cut off from the fluvial sediment supply become sites of shoreface incision into prodelta deposits regressive marine erosion and wave cut terraces are developed where sandy sediment is then supplied to the shoreface by rivers or updrift sources sharp based littoral sandbodies directly overlie the shoreface erosion surface other parts of the deltas below wave base that become abandoned through lobe switching can also be eroded by tidal currents deltas that have prograded into deep water show evidence of submarine slope instability such as submarine channel development base of slope turbidites and thick and thin skinned failures that disrupt clinoforms isopach trends reflect the existence of underlying structure with holocene sediments locally either thi ning or pinching over bedrock highs

compositional variations of the lunar crust results from radiative transfer modeling of central peak spectra 1 we present model mineralogy of impact crater central peaks combined with crustal thickness and crater central peak depth of origin models to report multiple perspectives of lunar crustal composition with depth here we report the analyses of 55 impact crater central peaks and how their compositions directly relate to the lunar highlands sample suite a radiative transfer model is used to analyze clementine visible plus near infrared spectra to place compositional constraints on these central peak materials central peaks analyzed are dominantly magnesian and plagioclase poor strong compositional similarities to lunar mg suite materials are evident relative to crustal thickness estimates central peak mineralogy becomes more plagioclase rich as the crust thickens relative to the crust mantle boundary the origin of peaks with dominantly mafic mineralogy are confined to the lower crust and primarily within the south pole aitken and procellarum kreep terranes pkt additionally central peaks with anorthositic mineralogy 60 vol plagioclase are transported to the surface from all depths in the crustal column and confined to the feldspathic highlands terrane fht the discovery of mafic and magnesian materials consistent with mg suite rocks of the sample collection in all lunar terranes suggests that the process and sources that give rise to these types of rocks is not unique to the pkt and not necessarily dependent on incompatible elements for formation the identification of ferroan and magnesian anorthositic material near the crust mantle boundary of the fht is also inconsistent with an increasing mafic feldspar ratio and mg with depth in the crust

the magma ocean concept and lunar evolution the model of lunar evolution in which the anorthositic plagioclase rich oldest crust of the moon is formed over a period of 300 myr or less by crystallization as it floats on a global ocean of magma tens or hundreds of km thick is examined in a review of petrological and theoretical studies consideration is given to the classification of lunar rocks the evidence for primordial deep global differentiation constraints on the depth of the molten zone the effects of pressure on mineral stability relationships mainly liquid vs mainly magmifer ocean models and the evidence for multiple ancient differentiation episodes a synthesis of the model of primordial differentiation and its aftereffects is presented and the generalization of the model to the earth and to mars mercury venus and the asteroids is discussed

lunar magma ocean crystallization revisited bulk composition early cumulate mineralogy and the source regions of the highlands mg suite abstract crystallization of the lunar magma ocean lmo has been numerically modeled and its products inferred from sample observations but it has never been fully tested experimentally this study is a reexamination of the lmo hypothesis by means of the first experimental simulation of lunar differentiation two end member bulk moon compositions are considered one enriched in refractory lithophile elements relative to earth and one with no such enrichment a two stage model of magma ocean crystallization based on geophysical constraints is simulated and features early crystal suspension and equilibrium crystallization followed by fractional crystallization of the residual magma ocean an initially entirely molten moon is assumed part 1 of this study presented here focuses on stage 1 of this model and considers the early cumulates formed by equilibrium crystallization differences in mantle mineralogy resulting from different bulk moon compositions and implications for the source regions of the highlands mg suite refractory element enriched bulk moon compositions produce a deep mantle that contains garnet and trace cr spinel in addition to low ca pyroxene and olivine in contrast compositions without refractory element enrichment produce a deep dunitic mantle with low ca pyroxene but without an aluminous phase the differences in bulk composition are magnified in the residual melt the residual lmo from the refractory element enriched composition will likely produce plagioclase and ilmenite earlier and in greater quantities both compositions produce mg rich early cumulate piles that extend from the core mantle boundary to 355 km depth if 50 equilibrium crystallization and whole moon melting are assumed these early lmo cumulates provide good fits for the source regions for a component of the high mg ni and co poor parental magmas of the mg suite cumulates if certain conditions are called upon the olivine in early lmo cumulates produced by either bulk moon composition is far too rich in cr to be reasonable for the source regions of the mg suite meaning either core formation in the presence of s and or c must be invoked to deplete the lmo and the crystallizing olivine in cr or that current estimates of the bulk lunar cr content are too high we infer that melts meeting the criteria of the mg suite parents could be produced from early lmo cumulates by solid state kreep and plagioclase hybridization near the base of the crust and subsequent partial melting additionally we propose a revised model for mg suite petrogenesis

late glacial stratigraphy and history of the gulf of st lawrence reply the three dimensional configuration of the quaternary sediments in the gulf of st lawrence is described based on analysis of 8000 km of high resolution seismic reflection data complemented by anal

morphodynamics in sediment starved inner shelf submarine canyons lower st lawrence estuary eastern canada abstract the contemporaneous activity and sedimentary processes in a series of inner shelf submarine canyons located in the lower st lawrence estuary were examined using high resolution multibeam bathymetry and backscatter data the presence of crescent shaped bedforms csbs displaced upslope at the bottom of the canyons between 2007 and 2012 indicates that they are currently active through the remobilization of sediment by gravity flows however the shelf and shores of the region are characterized by the absence of sediment our results indicate that gravity flows currently eroding the canyon floors do not transport new material downslope coming from the shelf but rather remobilize in situ deglacial sediments within the canyon thalweg we suggest that slope failures and internal tides waves are responsible for sediment remobilization in these canyons although their role in the upslope migrating csbs is unclear this paper provides evidence that sediment supply is not a prerequisite for the modern activity of inner shelf submarine canyons when processes such as slope failures and internal tides waves are frequent enough to remobilize in situ sediments

large scale subaerial and submarine holocene and recent mass movements in the betsiamites area quebec canada abstract at least three major landslide events formed the submarine and subaerial betsiamites quebec canada landslide complex and mobilized an estimated total volume of 2000 million m3 2 km3 linkage between offshore and onshore geophysical investigations with borehole data and in situ testing allows reconstruction of the architecture of the betsiamites river delta area and leads to the identification of the main failure events the submarine scar of the betsiamites landslide complex may have resulted from a first failure dated at about 9250 cal bp which mobilized a minimum volume of 200 million m3 a second landslide dated at 7250 cal bp mobilized a volume of 1300 million m3 over an area of 54 km2 the betsiamites submarine landslide event dated at 7250 cal bp left the largest scar yet identified on the st lawrence estuary seafloor furthermore this paper demonstrates that the subaerial scar of the betsiamites landslide complex is a result of the colombier landslide event which was initiated by the 1663 earthquake and involved four successive failure phases one submarine and three subaerial the february 5th 1663 earthquake triggered a submarine landslide event which reached the shoreline and led in a short period of time successively to two subaerial flowslides in sensitive clayey material and a subaerial lateral spread the four failure phases mobilized a possible total volume of about 530 million m3 over an area of 20 km2 the colombier landslide event is among the largest documented historic landslides in canada the presence of submarine scars left by the early holocene events acted as predisposition factors for the development of the failure while the earthquake of 1663 was the main triggering factor of the first submarine failure

crustal scale seismic profiles across the manila subduction zone the transition from intraoceanic subduction to incipient collision 1 we use offshore multichannel seismic mcs reflection and wide angle seismic data sets to model the velocity structure of the incipient arc continent collision along two trench perpendicular transects in the bashi strait between taiwan and luzon this area represents a transition from a tectonic regime dominated by subduction of oceanic crust of the south china sea west of the philippines to one dominated by subduction and eventual collision of rifted chinese continental crust with the luzon volcanic arc culminating in the taiwan orogeny the new seismic velocity models show evidence for extended to hyperextended continental crust 10 15 km thick subducting along the manila trench at 20 5 n along transect t1 as well as evidence indicating that this thinned continental crust is being structurally underplated to the accretionary prism at 21 5 n along transect t2 but not along t1 to the south coincident mcs reflection imaging shows highly stretched and faulted crust west of the trench along both transects and what appears to be a midcrustal detachment along transect t2 a potential zone of weakness that may be exploited by accretionary processes during subduction an additional seismic reflection transect south of t1 shows subduction of normal ocean crust at the manila trench

geomorphology and potential slope instability on the fraser river delta foreslope vancouver british columbia le delta du fleuve fraser est localise dans une des regions ayant les plus hauts risques sismiques au canada et comprend pour une bonne part des sables fluviaux meubles tres connus comme possedant un potentiel eleve de liquefaction sismique des etudes recentes de la rive ouest du delta du fraser indiquent que la liquefaction cyclique durant un fort tremblement de terre est possible engendrant potentiellement des deformations incluant des extensions laterales un ramollissement cyclique et possiblement une coulee l on presente une evaluation preliminaire de la stabilite statique des pentes apres secousse dans laquelle les analyses ont ete limitees aux valeurs estimees des resistances au cisaillement ultimes ou a l etat d equilibre deduites de correlations avec les donnnees du terrain et aux contraintes de cisaillement calculees en partant de la bathymetrie du lit de mer existant l on a trouve que le coefficient postliquefaction de securite contre le glissement etait inferieur a l unite pour la pente de la terrasse superieure roberts en supposant une limite inferieure de resistance au cisaillement ultime equivalente a 0 06 p 0 les donnees pour evaluer la validite de cette hypothese sont insuffisantes cependant il y a abondance de depots de rupture le long de la base de la pente du delta

evaluation of preconsolidation pressure and the overconsolidation ratio from piezocone tests of clay deposits in quebec the preconsolidation pressure and overconsolidation ratio profiles are the most important factors related to the mechanical behaviour of clay deposits they are interpreted on the basis of a limited number of laboratory tests but the near continuous information provided by the piezocone can allow local data to be extrapolated to an entire site numerous methods have been proposed for relating piezocone data to preconsolidation pressure and the overconsolidation ratio but their validity is still uncertain in this paper nine methods are compared on the basis of data collected on 31 sensitive clay sites in quebec whose preconsolidation pressure profiles are well known each method is briefly presented and the most promising are identified the simplest method which directly relates preconsolidation pressure to net tip resistance also appears to be the most effective key words clay preconsolidation pressure overconsolidation ratio piezocone correlations

large scale mass wasting events on the fraser river delta front near sand heads british columbia although the fraser river delta front supports coastal structures including ports a lighthouse jetties submarine power cables and sewage pipelines the stability of the delta front is little understood five large scale mass wasting events at the mouth of the main channel near sand heads have been detected by comparing successive bathymetric surveys conducted by public works canada between 1970 and 1986 these events can involve the downslope movement of more than 1 106 m3 of silty sand and the landward retrogression of the delta front crest of up to 350 m or more morphologic and sedimentologic evidence suggests that these events are slope failures which result from the liquefaction of silty sand rapid deposition at the river mouth is likely a prerequisite for failure although interstitial gas tidal currents waves and earthquakes also may contribute to failure these results have important implications for the foundation stability of the sand heads lighthouse and future coastal structures in t

possible mantle origin of olivine around lunar impact basins detected by selene the composition structure and evolution of the moon s mantle is poorly constrained a global survey of the moon s surface using the spectral profiler onboard the lunar explorer selene kaguya identifies a number of exposures of olivine in concentric regions around lunar craters with a possible mantle origin

an in hole shotgun source for engineering seismic surveys we have conducted several source comparisons involving 12 gauge and 8 gauge buffalo guns a 7 3 kg sledgehammer and a 75 kg weight drop the results are strongly site dependent we found that when the near surface consisted of fine grained water saturated sediments the 12 gauge buffalo gun produced up to two orders of magnitude more energy than the conventional hammer across a broad frequency range under such conditions the gun produced the greatest improvement in energy between 200 and 400 hz where it yielded up to ten times more energy than the 75 kg weight drop this indicates that the buffalo gun may be particularly useful as a shallow reflection seismic source however at sites where the near surface materials were coarse grained and the water table was well below the ground surface the advantages of using an in hole shotgun source as opposed to a hammer or weight drop were minimal nevertheless in many areas we believe that the buffalo gun is an excellent source for engineering seismic surv

a new lunar digital elevation model from the lunar orbiter laser altimeter and selene terrain camera abstract we present an improved lunar digital elevation model dem covering latitudes within 60 at a horizontal resolution of 512 pixels per degree 60 m at the equator and a typical vertical accuracy 3 to 4 m this dem is constructed from 4 5 10 9 geodetically accurate topographic heights from the lunar orbiter laser altimeter lola onboard the lunar reconnaissance orbiter to which we co registered 43 200 stereo derived dems each 1 1 from the selene terrain camera tc 1010 pixels total after co registration approximately 90 of the tc dems show root mean square vertical residuals with the lola data of

chronologie th u des concretions calcaires des varves du lac glaciaire de deschaillons wisconsinien inferieur late pleistocene lake deschaillons varves from the central st lawrence lowlands represent a lithostratigraphic unit whose upper limit is defined by the overlying gentilly till which was laid down

proprietes caracteristiques des argiles de l est du canada the compilation of numerous geotechnical data has allowed the definition of the main physical mechanical and hydraulic properties of marine and lacustrine clays of eastern canada as well as the establishment of correlations between some of these properties the possible uses of these correlations are described this study shows that the clays of eastern canada exhibit a behaviour similar to that of other clays but that they are characterized by a higher degree of structuration keywords physical properties mechanical properties hydraulic properties clays canada correlations journal translation

lunar mare volcanism stratigraphy eruption conditions and the evolution of secondary crusts abstract lunar mare basalt deposits cover 17 of the lunar surface occur preferentially in topographic lows on the nearside and have a total volume estimated at 1 107 km3 analysis of returned samples and photogeologic and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment the period of cryptomare formation in pre nectarian times and continued until the copernican period a total duration approaching 3 5 4 ga stratigraphic analyses show that the flux was not constant but peaked in early lunar history during the imbrian period which spans the period 3 85 3 2 ga average volcanic output rate during this peak period was about 10 2 km 3 a very low relative to the present global terrestrial volcanic output rate and comparable to the present local output rates for individual volcanoes such as vesuvius and kilauea hawaii volcanic landforms indicate that many eruptions were of high volume and long duration some eruptions associated with sinuous rules may have lasted of the order of a year and emplaced 103 km3 of lava representing the equivalent in one year of about 70 000 years at the average flux shallow magma chambers were uncommon the nearsidefarside mare deposit asymmetry can be readily explained by differences in crustal thickness magma ascending from the mantle or from a buoyancy trap at the base of the crust should preferentially extrude to the surface on the nearside but should generally stall and cool in dikes in the farside crust extruding only in the deepest basins the occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation dikes that establish pathways to the surface on the nearside should have very high volumes comparable to the volumes associated with many observed flows and sinuous rilles an abundance of dikes should exist in the lower crust of the moon many more than those feeding surface eruptions the upper limit is 37 50 of the crust by volume the presence and abundance of such dike swarms have important implications for the interpretation of the average composition of the lunar crust and the composition of basin and crater ejecta the interplay between thermal contraction and differentiation leads to net cooling and ultimate contraction of the outer portions of the moon resulting in a regional horizontal compressive stress acting on the lunar crust in addition overall cooling and deepening of sources require the production of ever larger volumes of magma in order to reach the surface with time stresses became high enough so that few dikes could open to the surface causing eruptive activity to be severely diminished in the eratosthenian and perhaps to cease in the copernican period lower stress levels are required to terminate eruptive activity on the lunar farside consistent with the imbrian age of the farside maria and the nearside location of the youngest maria lunar mare deposits provide an example of the transition from primary crusts to secondary crusts and illustrate the significance of several factors in the evolution of secondary crusts such as crustal density variations in crustal thickness presence of impact basins state and magnitude of stress in the lithosphere and general thermal evolution these factors are also responsible for the extremely low volcanic flux even during periods of peak extrusion

a massive sensitive clay landslide quyon valley southwestern quebec canada and evidence for a paleoearthquake triggering mechanism abstract a landslide debris field covering 31 km2 the presence of large sediment blocks up to hundreds of meters long and the exposure of deposits of a single landslide along the incised course of the quyon river are evidence of a massive failure of sensitive champlain sea glaciomarine sediments along the lower quyon valley southwestern quebec canada seventeen radiocarbon ages indicate that the failure occurred between 980 and 1060 cal yr bp twenty four additional radiocarbon ages reveal that nine landslides within a 65 km belt in the quyon ottawa area also occurred at approximately this time in combination the contemporaneous occurrence of ten landslides between 980 and 1060 cal yr bp the setting or morphology of five of the other failures and the close proximity of two of the failures to the quyon valley landslide provide circumstantial evidence of a paleoearthquake triggering mechanism the paleoearthquake is estimated to be mw 6 1 or larger with the epicenter within the west quebec seismic zone a common earthquake triggering mechanism for the three largest landslides in eastern canada suggests a close link between massive failures of sensitive glaciomarine sediments and the regional seismicity

effects of mass wasting on the stratigraphic architecture of a fjord valley fill correlation of onshore shear wave seismic and marine seismic data at trondheim norway abstract a combined record of onshore high resolution shear wave seismic and marine p wave seismic data shows the near shore stratigraphic organisation of a fjord valley fill at trondheim central norway the overall stratigraphy shows a typical fjord valley fill of up to 160 m in thickness that is composed of glaciomarine and fjord marine sediments overlain by deltaic deposits which in the onshore section are draped by an anthropogenic fill an interval characterised by low shear wave velocities below the onshore anthropogenic fills is shown by sampled drillings to comprise part clay and part organic deposits the seismic record reveals evidence of recurrent mass wasting events that include landslide debris turbidite deposits and channel features a chronological framework for the stratigraphy is provided by existing radiocarbon dates for local deglaciation and mass wasting events the combined onshore offshore datasets document the lateglacial to holocene development of an emerging fjord and delta system affected by major mass wasting events the architectural development of the younger part of the stratigraphy is interpreted as particularly affected by two known mass wasting events each involving several million m 3 of debris a thick layer of debris from a 3500 cal yr event probably resulted in a blockage of the subaqueous channels diversion of turbidity currents and deposition of lateral accretion packages whereby local fjord sedimentation temporarily increased a 2200 cal yr event resulted in a sudden reorganisation of the distributary system whereby distal delta sedimentation abruptly shifted north to northeastwards to an area temporarily subjected to marine erosion during fall of relative sea level the study adds to the understanding of landslides and low stiffness zones in the area of importance for near shore geohazard assessment the study also provides insight into the stratigraphic variability of fjord valley fills and highlights the interplay between fjord marine sedimentation marine abrasion delta progradation and mass wasting during late stages of fjord filling

a high resolution holocene paleomagnetic secular variation and relative paleointensity stack from eastern canada abstract a high resolution holocene paleomagnetic secular variation psv and relative paleointensity rpi stack was constructed using u channel paleomagnetic data from six radiocarbon constrained marine sedimentary sequences raised along the main axis of the laurentian channel eastern canada from its head to its mouth centennial to millennial scale declination and inclination features of the eastern canadian stack can be correlated within the dating uncertainties with other holocene north american icelandic and european psv records suggesting a common possibly hemispheric in character geomagnetic origin both magnetic inclination and declination of the eastern canadian stack are generally consistent with the time varying spherical harmonic model of the geomagnetic field cals7k 2 notably during the last 4000 cal bp in addition the eastern canadian holocene rpi stack reveals similar millennial and even centennial time scale variations consistent with some virtual axial dipole moment vadm reconstructions derived from absolute paleointensity data as well as with north american lacustrine rpi records accordingly these results suggest that the holocene paleomagnetic secular variation in north america is significantly driven by large scale 5000 km geomagnetic field changes at these timescales

bulk mineralogy of lunar crater central peaks via thermal infrared spectra from the diviner lunar radiometer a study of the moon s crustal composition at depth 1 the central peaks of lunar impact craters are thought to be composed of uplifted material originating from varying depths of the crustal column the interpreted crystallization sequence of the early lunar magma ocean resulted in an anorthositic upper crust that may become progressively more mafic as it approaches the olivine rich mantle emissivity spectra from the lunar reconnaissance orbiter lro diviner radiometer are used to derive the wavelength location of the christiansen feature cf which is sensitive to bulk silicate mineralogy here a survey of cf values has been performed for the central peaks of 135 complex craters providing global and regional observations of the heterogeneity of crustal compositions crustal thickness models give context to the preimpact depth of the central peak material and its proximity to the crust mantle boundary this study has identified six craters with potentially ultramafic compositions within their central peaks more common occurrences of mafic material found in a wide variety of crater central peaks show a silicate composition roughly similar to mare basalt or an olivine bearing gabbro the range of central peak cf values is similar to that of the rest of the lunar surface bulk mineralogy of the central peak material does not appear to be correlated with its crustal depth of origin suggesting both lateral and vertical heterogeneity in crustal composition rather than a gradual transition from felsic to mafic composition it is likely that the moon s extensive cratering history has continually overturned the original crust erasing any original systematic dependence of composition on depth or proximity to the mantle

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

measuring moonlight an overview of the spatial properties lunar coverage selenolocation and related level 1b products of the moon mineralogy mapper 1 the moon mineralogy mapper m3 a high resolution high precision imaging spectrometer flew on board india s chandrayaan 1 mission from october 2008 through august 2009 this paper describes some of the spatial sampling aspects of the instrument the planned mission and the mission as flown we also outline the content and context of the resulting level 1b spatial products that form part of the m3 archive while designed and planned to operate for 2 years in a 100 km lunar orbit m3 was able to meet its lunar coverage requirements despite the shortened mission an increase of the orbit altitude to 200 km and several relevant problems with spacecraft attitude timing and ephemeris the unexpected spacecraft issues required us to invent a novel two step approach for selenolocation leveraging newly available lunar reconnaissance orbiter lunar orbiter laser altimeter lola topography and an improved spacecraft ephemeris we have created a method that permits us to bootstrap spacecraft attitude estimates from the image data themselves this process performs a nonlinear optimization to honor a set of data derived image to image tie points and image to lola control points error analysis of the final results suggests we have converged to a selenolocation result that has image to image root mean square rms errors less than 200 m and image to lola rms errors less than 450 m despite using data derived spacecraft attitude results the level 1b products include the lunar coordinates resulting from this inversion process and 10 relevant observational geometry parameters that fully characterize the ray tracing geometry on a pixel by pixel basis

identification and dating of a key late pleistocene stratigraphic unit in the st lawrence estuary and gulf eastern canada abstract a recently acquired 8 m long sediment core along with high resolution seismic reflection and subbottom profiler sections allowed the identification characterization and dating of a widespread seismic unit extending from the head of the laurentian channel lower st lawrence estuary to honguedo strait gulf of st lawrence eastern canada this seismic unit labelled unit 2 is characterized by a series of parallel high amplitude reflections with thicknesses ranging from 68 m near the head of the laurentian channel to 250 m in the st lawrence estuary leaving it very difficult to be reached by conventional coring operations here we reveal how we were able to trace and core this seismic unit in an area where it lays closer to the seafloor near the southern wall of the laurentian channel in the lower st lawrence estuary this seismic unit consists of two sedimentary facies sandy mud including ice rafted debris ird underlying faintly laminated to homogenous and plastic silty clays based on the sedimentary facies we interpret the upper clays as ice distal glaciomarine sediments and the lower sandier sediments as ice proximal glaciomarine sediments this interpretation is further supported by the fact that no seismic nor sediment facies present above seismic unit 2 throughout the estuary and gulf of st lawrence can be linked to glacial i e ice contact sediments such as till moraines esker etc sediments seismic unit 2 is highly disturbed by iceberg scouring in the gulf of st lawrence where it is found at shallower depths indicating that it was deposited during deglaciation the available ams 14c dates obtained in the ice proximal glaciomarine sediments indicate that the lower part of seismic unit 2 was deposited during local re advances or stillstands of the laurentide ice sheet margins in the goldthwait sea that began at or before the younger dryas cold event 11 100 10 000 yr bp and that seismic unit 2 can be used as a chronostratigraphic marker throughout the st lawrence estuary and northwestern gulf of st lawrence

mineralogical diversity and geology of humboldt crater derived using moon mineralogy mapper data moon mineralogy mapper m3 spectroscopic data and high resolution imagery data sets were used to study the mineralogy and geology of the 207 km diameter humboldt crater analyses of m3 data using a custom made method for m3 spectra continuum removal and spectral parameters calculation reveal multiple pure crystalline plagioclase detections within the humboldt crater central peak complex hinting at its crustal origin however olivine spinel and glass are observed in the crater walls and rims suggesting these minerals derive from shallower levels than the plagioclase of the central peak complex high calcium pyroxenes are detected in association with volcanic deposits emplaced on the crater s floor geologic mapping was performed and the age of humboldt crater s units was estimated from crater counts results suggest that volcanic activity within this floor fractured crater spanned over a billion years the felsic mineralogy of the central peak complex region which presumably excavated deeper material and the shallow mafic minerals olivine and spinel detected in humboldt crater walls and rim are not in accordance with the general view of the structure of the lunar crust our observations can be explained by the presence of a mafic pluton emplaced in the anorthositic crust prior to the humboldt forming impact event alternatively the excavation of australe basin ejecta could explain the observed mineralogical detections this highlights the importance of detailed combined mineralogical and geological remote sensing studies to assess the heterogeneity of the lunar crust

spectral characteristics of lunar impact melts and inferred mineralogy abstract two suites of lunar impact melt samples have been measured in nasa s reflectance experiment laboratory relab at brown university suite 1 comprises seven apollo 17 crystalline impact melt breccias and seven quenched glass equivalents suite 2 is made up of 15 additional impact melt samples from apollo 12 15 16 and 17 which exhibit a range of textures and compositions related to cooling conditions and glass abundance a few of these samples have cooled slowly and fully crystallized and thus have the same spectral properties as igneous rocks of similar texture and composition they cannot be uniquely distinguished without geologic context however most of the impact melts and melt breccias contain either quantities of quenched glass and or have developed microcrystalline nonequilibrium textures with well defined diagnostic spectral properties the microcrystalline textures are associated with a distinctive 600 nm absorption feature apparently due to submicroscopic ilmenite inclusions in a transparent host typically fine grained plagioclase the reflectance properties of these lunar sample suites contribute to and constrain the identification and characterization of impact melts in remote sensing data

mg spinel lithology a new rock type on the lunar farside 1 high resolution compositional data from moon mineralogy mapper m3 for the moscoviense region on the lunar farside reveal three unusual but distinctive rock types along the inner basin ring these are designated oos since they are dominated by high concentrations of orthopyroxene olivine and mg rich spinel respectively the oos occur as small areas each a few kilometers in size that are widely separated within the highly feldspathic setting of the basin rim although the abundance of plagioclase is not well constrained within the oos the mafic mineral content is exceptionally high and two of the rock types could approach pyroxenite and harzburgite in composition the third is a new rock type identified on the moon that is dominated by mg rich spinel with no other mafic minerals detectable 5 pyroxene olivine all oos surfaces are old and undisturbed since basin formation they are effectively invisible in image data and are only recognized by their distinctive composition identified spectroscopically the origin of these unusual lithologies appears to be linked to one or more magmatic intrusions into the lower crust perhaps near the crust mantle interface processes such as fractional crystallization and gravity settling within such intrusions may provide a mechanism for concentrating the mafic components within zones several kilometers in dimension the oos are embedded within highly anorthositic material from the lunar crust they may thus be near contemporaneous with crustal products from the cooling magma ocean

radiative transfer model constraints on the shock state of remotely sensed lunar anorthosites 1 near ir spectra of some lunar basin rings and crater central peaks exhibit no evidence of absorption due to ferrous iron unlike all other spectral measurements of lunar soil in the laboratory or obtained remotely these spectral anomalies have previously been interpreted to indicate the presence of a deposit of essentially pure plagioclase feldspar anorthosite which has been shocked above 250 kb plagioclase possesses a diagnostic absorption feature near 1250 nm caused by trace ferrous iron that is lost when shocked above 250 kb whereas ferrous features of pyroxene are robust against shock however new methods for computing the optical effects of exposure of lunar materials to the space environment show that these optical effects can obscure the spectral features of plagioclase without resorting to shock modification of the plagioclase structure our modeling shows that shock is not necessary to explain the apparent lack of absorption but is not excluded either thus previous reports that some lunar surface features may have experienced high shock levels are not supported

seismotectonic characteristics of the lower st lawrence seismic zone quebec insights from geology magnetics gravity and seismics the estuary of the st lawrence river between baie comeau and sept iles is an area where 50 to 100 earthquakes are detected yearly this study defines the major lineaments of the precambrian basement and compares them with mapped faults where possible and examines their possible correlation with the local earthquakes onshore aerial photographs remote sensing images and field mapping are used to identify the geological structures of the precambrian basement while offshore they are interpreted from potential field magnetic gravity and a published synthesis of seismic reflection profiles the precambrian basement dips towards the southeast under the appalachian nappes with normal faults with kilometre scale throw and east west or ene wsw strikes onshore a system of normal brittle faults with a complex history of movements crosscuts both the precambrian basement and the overlying ordovician sedimentary cover most earthquakes occur beneath the st lawrence river at focal depths between about 7 and

unexpected fast rate of morphological evolution of geologically active continental margins during quaternary examples from selected areas in the italian seas abstract in the last few decades seafloor imagery systems have drastically changed our vision of a mostly regular and depositional marine landscape evidencing how erosive and mass wasting processes are widespread in the marine environments with particular reference to geologically active areas most of the previous studies have focused on the characterization of these features whereas a very few ones have tried to estimate what is the extent and order of magnitude of erosion rates in these areas in this paper we show several examples from some of the most geologically active margins off southern italy aimed to a quantify the spatial extent of such processes b better understand the role of submarine erosion in the morphogenesis of the coastal sector and c try to roughly estimate the order of magnitude of erosion rates in these areas the results are impressive with mass wasting features widespread from coast down to 2600 affecting from the 52 up to 97 of the whole continental slope because of the narrow or totally lacking shelves in these areas mass wasting processes often occur close to the coast and match embayment of the coast so indicating a key role in the morphogenesis of coastal sector with significant implication on the related geohazard finally based on a morphological approach integrated by available stratigraphic constraints we have roughly estimated average erosion rates in these areas ranging from at least some mm year to a few cm year i e some hundreds of meters up to kilometers eroded in each eustatic cycle despite the large uncertainties of these estimates as well as their spatial and temporal variability in response to regional and local factors the obtained values are very high and they should be considered for future model of margin evolution source to sink computation and marine coastal geohazard assessment

a chemical model for generating the sources of mare basalts combined equilibrium and fractional crystallization of the lunar magmasphere abstract it is generally considered that mare basalts were generated by the melting of a cumulate mantle formed in an early moon wide magma ocean or magmasphere however the nature and chemistry of this cumulate mantle and the logistics of its origin have remained elusive extensive studies of terrestrial layered mafic intrusions over the past sixty years have emphasized the imperfection of fractional crystallization and attendant crystal crystal and crystal liquid separation in a convecting magma chamber crystal liquid and crystal crystal separations were similarly inefficient during evolution of the lunar magma ocean lmo allowing for the trapping of interstitial liquid and entrainment of a small proportion of less dense plagioclase into the denser mafic cumulate mush indeed petrography of lunar highlands samples demonstrates this for anorthosites with 1 10 olivine the residual liquid after 80 90 crystallization was very evolved in fact kreepy and even in small proportions 1 5 would have a noticeable effect on the trace element chemistry of melts generated from these cumulates this trapped residual liquid would elevate total ree abundances in the cumulate pile while synchronously deepening the already negative eu anomaly essentially this trapped liquid will make the cumulate more fertile for melting to generate both kreep basalt and mare basalt magmas plagioclase entrained in the mafic cumulate pile adds an essential al component to the high ti basalt source and will moderate the requisite negative eu anomaly in the cumulate early in the evolution of the lunar mantle when the lmo still was largely liquid it is likely that vigorous convection was an important factor in crystallization such convection would allow crystals to remain suspended and in equilibrium with the lmo liquid for relatively long periods of time this extended period of equilibrium crystallization would then have been followed by fractional crystallization once plagioclase became a liquidus phase and began to float to form the lunar highlands crust previous authors have proposed a three component model for the evolution of high ti mare basalt source regions this model includes kreep early olivine rich high mg cumulates and late ilmeniterich low mg cumulates in various proportions however we propose a model for high ti basalt parent magmas which is in accord with studies of terrestrial layered intrusions this model for the high ti source includes trapped instantaneous residual liquid tirl 1 3 and entrainment of a small 2 5 proportion of plagioclase into the late stage cumulate pile in order to account for both the observed al compositions and trace element characteristics of high ti mare basalts melting of this relatively shallow ilmenite and clinopyroxene bearing late stage cumulate can generate high ti mare basalt magmas furthermore we are in agreement with other workers that only through a process of nonmodal melting will the high ti values for the parent magmas be realized large scale convective overturn of the cumulate pile and mixing of kreep with early and late stage cumulates is not required however localized overturn of the upper tenth of the cumulate pile is likely and in fact required to achieve an appropriate major element balance for the high ti mare basalt source region

holocene paleomagnetic records from the st lawrence estuary eastern canada centennial to millennial scale geomagnetic modulation of cosmogenic isotopes two long holocene piston cores md99 2220 and md99 2221 were raised from the st lawrence estuary eastern canada because of the expanded holocene sediment sequence this location provides a u channel based paleomagnetic study supported by an accelerator mass spectrometry ams 14c chronology rock magnetic and sedimentological data indicates that these sediments provide a paleomagnetic directional secular variation psv and relative paleointensity rpi proxy records for the last 8500 cal bp sedimentation rates vary from 1 2 to 4 2 m kyr comparison of inclination and declination features with other north american holocene psv records are generally consistent and temporal offsets are within chronological uncertainties the normalized natural remanent magnetization intensity record a rpi proxy from the postglacial sediments of core 2220 compares favorably with north american and european holocene rpi records at millennial and even some centennial timescales comparisons between core 2220 rpi proxy and the 10be flux record from the greenland summit gisp2 ice core finkel and nishiizumi j geophys res 102 1997 26699 26706 and a 14c production rate record bond et al science 294 2001 2130 2136 suggest that geomagnetic modulation may control the millennial and even some centennial scale variability within cosmogenic isotope records this implies that the core 2220 rpi record reflects changes in global scale geomagnetic field at these timescales

compositional diversity at theophilus crater understanding the geological context of mg spinel bearing central peaks 1 analysis of high resolution moon mineralogy mapper m3 data reveals the presence of a prominent mg spinel rich lithology in the central peaks of theophilus crater on the lunar nearside other peak associated lithologies are comprised of plagioclase olivine and pyroxene bearing materials a consistent spatial association of mg spinel with mafic free anorthosite is recognized documentation of theophilus central peaks brings the global inventory of mg spinel rich lithology to two widely separated occurrences namely theophilus on the lunar nearside and moscoviense basin on the farside the theophilus crater target region lies on one of the inner rings of the nectaris basin indicating that the mg spinel bearing lithology source was deep in the lunar crust

compositional diversity and geologic insights of the aristarchus crater from moon mineralogy mapper data 1 the moon mineralogy mapper m3 acquired high spatial and spectral resolution data of the aristarchus plateau with 140 m pixel in 85 spectral bands from 0 43 to 3 0 m the data were collected as radiance and converted to reflectance using the observational constraints and a solar spectrum scaled to the moon sun distance summary spectral parameters for the area of mafic silicate 1 and 2 m bands were calculated from the m3 data and used to map the distribution of key units that were then analyzed in detail with the spectral data this analysis focuses on five key compositional units in the region 1 the central peaks are shown to be strongly enriched in feldspar and are likely from the upper plagioclase rich crust of the moon 2 the impact melt is compositionally diverse with clear signatures of feldspathic crust olivine and glass 3 the crater walls and ejecta show a high degree of spatial heterogeneity and evidence for massive breccia blocks 4 olivine strongly concentrated on the rim wall and exterior of the southeastern quadrant of the crater is commonly associated the impact melt 5 there are at least two types of glass deposits observed pyroclastic glass and impact glass

stress evolution and seismic hazard of the dead sea fault system abstract we calculated the stress evolution for the central part of the dead sea fault system 30 5 n 34 5 n from 551 to 2005 through modelling the static stress changes due to 14 historical earthquakes with m s 6 0 superimposed by tectonic loading from relative plate motion from the results of our numerical models we identified two segments with high positive changes in coulomb failure stress cfs exceeding 4 mpa a 90 km long segment of the jordan fault south of the sea of galilee and a 30 km long segment east of the dead sea these segments could result in m s 7 4 and m s 6 8 earthquakes respectively in contrast to similar stress evolution models of other continental transform faults our results support only partly the hypothesis that coseismically induced static stress changes control the spatial succession of earthquakes we calculated on each rupture plane the mean of cfs and the maximum cfs due to the stress changes of all preceding earthquakes the results of the calculated mean cfs values reveal that only 6 out of 13 earthquakes could have been triggered the subsequent earthquake from the analysis of the maximum cfs values we find that 8 out of 13 earthquakes could have triggered the subsequent earthquake since our model results are sensitive to location and magnitude of historical earthquakes and the tectonic loading rates of the fault segments we emphasize the need for further paleoseismological studies and current slip rate estimation from continuously observing gps arrays and geological investigations taking into account that six large cities beirut damascus haifa tel aviv amman and jerusalem are in close proximity with distances between 30 and 150 km to the jordan segment the seismic risk is probably higher than accounted before