heat producing elements and the thermal and baric patterns of metamorphic belts the character of sedimentary basins before they are deformed and metamorphosed may strongly influence the thermal and baric patterns of metamorphic belts crustal thickening of anoxic sedimentary basins and subsequent thermal reequilibration may produce large areas of high grade metamorphic rocks and granites because the concentrations of the heat producing elements are high in such basins in new england there is a spatial association among granites and high grade metasedimentary rocks rich in u and th that now form the central maine terrane the high content of heat producing elements in these rocks is attributed to fixing of u and th in highly reduced sediments that were deposited in an anoxic basin that formed in the silurian when the basin was thickened during the devonian acadian orogeny the thermal energy generated by the u and th rich sediments produced the observed broad zone of high grade rocks and anatectic granites this hypothesis was tested with thermal calculations that reproduce most of the first order thermal and baric patterns of the acadian appalachians if pretectonic lateral variations in heat production are assumed

ages of some intrusive rocks of southwestern maine u s a whole rock rb sr and u pb zircon age measurements on intrusive rocks in southwestern maine indicate igneous activity at 400 340 and 320 ma these plutonic rocks were emplaced into deformed ordovi

the early environment and its evolution on mars implication for life there is considerable evidence that the early climate of mars was very different from the inhospitable conditions there today this early climate was characterized by liquid water on the surface and a dense atmosphere composed predominantly of co2 the duration of these warm initial conditions on the surface of mars is uncertain but theoretical models suggest that they could have persisted for hundreds of millions up to a billion years from studies of the earth s earliest biosphere we know that by 3 5 gyr ago life had originated on earth and reached a fair degree of biological sophistication surface activity and erosion on earth make it difficult to trace the history of life before the 3 5 gyr time frame if mars did maintain a clement environment for longer than it took for life to originate on earth then the question of the origin of life on mars follows naturally the fossil evidence of early life on earth provides clues as to what form fossils on mars might take of particular interest are stromatolites macroscopic layered structures that result from the anchoring of sediments by microorganisms living in the photic zone since over two thirds of the martian surface is more than 3 5 gyr old the possibility exists that mars may hold the best record of the events that led to the origin of life even though there may be no life there today

deep crustal carbonate rocks exposed by meteor impact on mars mars may have once had a co2 rich atmosphere but carbonate rocks that could provide evidence for such conditions are sparse spectral analyses of rocks exposed from deep within an impact crater reveal that carbonate deposits may be extensive on mars but are buried under layers of younger volcanic rocks

a spectroscopic method for identifying terrestrial biocarbonates and application to mars abstract searching for traces of extinct and or extant life on mars is one of the major objectives for remote sensing and in situ exploration of the planet in previous laboratory works we have investigated the infrared spectral modifications induced by thermal processing on different carbonate samples in the form of fresh shells and fossils of different ages whose biotic origin is easily recognizable the goal was to discriminate them from their abiotic counterparts in general it is difficult to identify biotic signatures especially when the organisms inducing the carbonate precipitation have low fossilization potential i e microbes bacteria archaea a wide variety of microorganisms are implicated in carbonate genesis and their direct characterization is very difficult to evaluate by traditional methods both in ancient sedimentary systems and even in recent environments in the present work we apply our analysis to problematic carbonate samples in which there is no clear evidence of controlled or induced biomineralization this analysis indicates a very likely biotic origin of the aragonite samples under study in agreement with the conclusion previously reported by guido et al 2007 who followed a completely different approach based on a complex set of sedimentary petrographic geochemical and biochemical analyses we show that our method is reliable for discriminating between biotic and abiotic carbonates and therefore it is a powerful tool in the search for life on mars in the next generation of space missions to the planet

early devonian kess kess carbonate mud mounds of the eastern anti atlas morocco and their relation to submarine hydrothermal venting abstract spectacular conical early devonian carbonate buildups up to 55 m high that crop out in the eastern anti atlas of southern morocco are microbially mediated carbonate mud mounds that were surfaced by soft bottom communities dominated by small tabulate corals they formed on the hamar laghdad elevation which was created by a submarine volcanic eruption and were associated with a network of synsedimentary radial and tangential faults that originated by uplift of the intrusive laccolithic body underlying the kess kess formation these faults served as conduits for the migration of hydrothermal fluids to the sea floor most mounds developed over cross points of radial and tangential faults vents were episodically active until the famennian but extensive vent carbonate production occurred only during the emsian preliminary geochemical results document that mud mound carbonates and calcite cements in neptunian dikes precipitated from brines comprising a mixture of hydrothermal fluids and seawater in addition carbon isotope compositions 13c as low as 18o oo pdb suggest a contribution from thermogenic methane derived presumably from underlying basaltic intrusives aerobic bacterial oxidation of methane is favored as the main process driving carbonate precipitation in and rapid lithification of the mounds

hydrated silicate minerals on mars observed by the mars reconnaissance orbiter crism instrument phyllosilicates a class of hydrous mineral first definitively identified on mars by the omega observatoire pour la mineralogie l eau les glaces et l activitie instrument preserve a record of the interaction of water with rocks on mars global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy fe mg and al smectite clays this was interpreted to indicate that phyllosilicate formation occurred during the noachian the earliest geological era of mars and that the conditions necessary for phyllosilicate formation moderate to high ph and high water activity were specific to surface environments during the earliest era of mars s history here we report results from the compact reconnaissance imaging spectrometer for mars crism of phyllosilicate rich regions we expand the diversity of phyllosilicate mineralogy with the identification of kaolinite chlorite and illite or muscovite and a new class of hydrated silicate hydrated silica we observe diverse fe mg oh phyllosilicates and find that smectites such as nontronite and saponite are the most common but chlorites are also present in some locations stratigraphic relationships in the nili fossae region show olivine rich materials overlying phyllosilicate bearing units indicating the cessation of aqueous alteration before emplacement of the olivine bearing unit hundreds of detections of fe mg phyllosilicate in rims ejecta and central peaks of craters in the southern highland noachian cratered terrain indicate excavation of altered crust from depth we also find phyllosilicate in sedimentary deposits clearly laid by water these results point to a rich diversity of noachian environments conducive to habitability

alkaline lake systems with stromatolitic shorelines in the ediacaran volcanosedimentary ouarzazate supergroup anti atlas morocco abstract in the zenaga and saghro inliers of the anti atlas morocco the ediacaran ouarzazate volcanosedimentary supergroup preserves a record of the complex interplay between effusion of lava floods and explosive volcanic activity from numerous separate volcanic centres volcanic units consist of basaltic and andesitic lava flows and subvolcanic sills and dikes and dacitic rhyolitic ignimbrites and tuffs that represent a post collisional high k calc alkaline magmatism volcanic events are separated by erosive and low angle unconformities related to regional tilting which mark significant hiatii in the timing of deposition and are locally marked by carbonate production in palaeoweathered lowlands infill of scattered decametre scale carbonate bearing troughs less than 1 km across started with the dominantly local derivation of weathered and eroded lava debris followed by the migration of scattered subaqueous bottomset and foreset structures and final nucleation of carbonate productivity microbial mats developed along the shorelines of these ponds when bathymetry increased the stromatolites developed domal to columnar morphologies that coalesced laterally to form metre thick biostromes the lack of evidence for significant fluvial and deltaic deposits suggests that the streams that entered the ponds were intermittent and thus not a significant source of water it appears that groundwater rather than surface water was the dominant source of water to sustain the ephemeral ponds in the low lying weathered palaeodepressions preserved in the ouarzazate supergroup fluids passing through the surrounding volcanic landscape and the volcanic ashes interbedded within the lacustrine infill supplied silica enriched fluids giving the ponds the characteristics of alkaline lake systems their lacustrine affinity is supported by the subaerial character of many of the volcanic products that surround them ree composition of partly silicified dolomitized and undolomitized stromatolites is entirely consistent with freshwater lacustrine or shallow lagoonal with a strong freshwater input depositional settings but they also display a strong contamination from the rhyolitic tuffs that overly them

proterozoic stromatolitic microbiotas of the 1400 1500 ma old gaoyuzhuang formation near jixian northern china abstract two communities of diverse well preserved fossil prokaryotic microorganisms have been discovered in petrographic thin sections of carbonaceous black chert from the ca 1400 1500 ma old gaoyuzhuang formation at the stratotype section of the sinian suberathem near jixian northern china one of these communities is preserved in bedded essentially flat laminated stromatolitic chert the other occurs in silicified conical stromatolites of the forms conophyton cylindricum and c garganicum the gaoyuzhuang cherts comprise one of the few microfossiliferous deposits now known from the precambrian of china the permineralized microbiotas they contain are among the first such stromatolitic assemblages to be discovered in the sinian stratotype section

observations and controls on the occurrence of inherited zircon in concord type granitoids new hampshire u pb analyses of zircons separated from two concord type plutons near sunapee and dixville notch new hampshire reveal differences in the pattern and magnitude of zircon inheritance which are related to differences in melt chemistry the sunapee pluton contains only slightly more zr than required to saturate the melt at the peak temperature of 700 30 sup 0 c traces of inherited zircon in this separate are inferred to be present as small largely resorbed grains in contrast the long mountain pluton near dixville notch contains about 240 more zr than required to saturate the melt thus more than half of the zr existed as stable inherited zircon crystals during the partial fusion event consistent with the observation of substantial inheritance in all grain size fractions ion probe intra grain analyses of zircon from the long mountain pluton indicate a complex pattern of inheritance with contributions from at least two proterozoic terranes and caution against simple interpretations of upper and lower intercepts of chords containing an inherited component ion probe analyses of zircons from the sunapee pluton reveal clear evidence of u loss which results in incorrect apparent conventional u pb ages ages of crystallization for the long mountain and sunapee pluton are approx more 350 and 354 5 ma respectively a sm nd measurement for the long mountain pluton yields a depleted mantle model age of 1 5 ga consistent with the observed inheritance pattern in contrast a sm nd model age for the sunapee pluton is improbably old due to minor monazite fractionation less

regional differences in pb isotopic compositions of feldspars in plutonic rocks of the northern appalachian mountains u s a and canada a geochemical method of terrane correlation feldspar pb isotopic compositions from paleozoic tonalitic to leucogranitic caledonian plutons from the northern appalachian mountains of the u s a and canada range from nonradiogenic to radiogenic relative to the evolution curve of stacey and kramers 1975 pb isotopic values in the feldspars are generally independent of modal and major and trace element contents of the plutons plutons with the least radiogenic pb isotopic signatures northern group have intruded allochthonous rocks closest to the north american craton and plutons with the most radiogenic pb southern group have intruded avalonian basement feldspars from plutons in the central group have intermediate pb isotopic compositions between the northern and southern groups and do not define an isotopically unique group the predominant source of the felsic magmas was the continental lithosphere as indicated by the general pb isotopic similarity of the plutonic feldspars with either grenville or chain lakes basement in the case of the northern group and with avalonian basement rocks in the case of the southern group the source region for plutons in the central group may have contained a mixture of grenvillian and avalonian components plutons in the northern appalachians are as a group more evolved in their pb isotopic compositions relative to caledonian plutons in the british isles

identification of carbonate rich outcrops on mars by the spirit rover decades of speculation about a warmer wetter mars climate in the planet s first billion years postulate a denser co2 rich atmosphere than at present such an atmosphere should have led to the formation of outcrops rich in carbonate minerals for which evidence has been sparse using the mars exploration rover spirit we have now identified outcrops rich in magnesium iron carbonate 16 to 34 weight percent in the columbia hills of gusev crater its composition approximates the average composition of the carbonate globules in martian meteorite alh 84001 the gusev carbonate probably precipitated from carbonate bearing solutions under hydrothermal conditions at near neutral ph in association with volcanic activity during the noachian era

are strongly peraluminous magmas derived from pelitic sedimentary sources igneous compositions that require the presence of a phase more aluminous than biotite are here designated as strongly peraluminous ps such compositions are common but subordinate in felsic rocks and exceedingly rare in more mafic rocks the term s type has been applied to many igneous rocks based largely or even solely upon their ps compositions neglecting or placing less emphasis on other criteria for sedimentary parentage in chappell and white s i and s type classification system the s type designation was in fact initially restricted to granites which were thought to have been derived from a chemically mature strongly weathered pelitic shaly source application of chappell s and white s criteria together with others based upon isotopic and phase equilibria considerations leads to the following conclusions about ps igneous rocks worldwide 1 very few ps rocks are derived entirely from pelitic sources 2 a majority are derived largely from intermediate to felsic crustal sources including

hydrothermal origin of devonian conical mounds kess kess of hamar lakhdad ridge anti atlas morocco various interpretations have been proposed for the origin of peculiar cone shaped finely crystalline devonian carbonate mounds of the hamar lakhdad ridge anti atlas morocco ranging from shallow water reefs to deep water mud mounds formed by biogenic and or hydrodynamic processes this study is the first integrated sedimentological and geochemical analysis of these structures the mounds are cone shaped steep sided circular to subelliptical in plan view and exhibit internal crude bedding parallel to the mound9s outer surface they occur in a cluster of 48 mounds on top of a volcanic massif stable isotope analyses of first stage isopachous nonluminescent cement have yielded marine values in contrast the finely crystalline carbonate that makes up the bulk of the mound and the internally sedimented mud between crusts of early marine cements have significantly lower 18 o values whereas values of 13 c are similar to those of the early marine cement strontium isotope ratios also clearly distinguish the nonluminescent early marine cements from the finely crystalline material the 87 sr 86 sr values for the former 0 707 934 0 709 392 are in or near the devonian marine range whereas the ratios for the latter 0 708 515 0 709 656 indicate a more radiogenic sr source on the basis of their lithology architecture isotope geochemistry and clustered occurrence on top of a volcanic pile we propose that the finely crystalline material that forms the mounds and the intermound beds was precipitated from hydrothermal fluids and that accretion of the material was driven by hydrothermal venting

defining biominerals and organominerals direct and indirect indicators of life abstract by introducing the new term organomineral to apply to minerals that are affected by organics mostly life related but not directly produced by living cells we hope to increase the accuracy of the terminology in present usage we believe that the term biomineral does not describe all mineral deposits precisely enough and offer case studies to support instances where the use of the new term organomineral is more appropriate we provide examples of some materials that are biominerals such as those in diatoms and human bones and which perform a functional purpose we then attempt to show that terminology can sometimes mislead investigators drive the direction and prejudice interpretations of scientific investigation this is achieved by presenting case studies of minerals that have been investigated as biominerals although they may not actually be directly controlled by biology for this reason we pay special attention to desert varnish hot spring siliceous deposits stromatolites and bacterial encrustations we go on to explain why we regard biominerals as direct indictors of life whereas organominerals should be treated as indirect indicators of life that require careful characterization to establish the origin of contained organics and whether these are biotic in origin how organic compounds are preserved and transformed in sedimentary environments and in the mineral matrix is as highly relevant to the study of modern earth environments as it is in the search for the oldest evidence of life in the terrestrial rock record it is also important to many disciplines such as microbiology and archaeology and especially to scientists planning missions to look for evidence of life on other planetary surfaces

secular variation in abiotic marine carbonates constraints on phanerozoic atmospheric carbon dioxide contents and oceanic mg ca ratios abiotic marine carbonates have been precipitated as ooids and synsedimentary cement within shallow marine carbonate sequences throughout the phanerozoic these components exhibit variable abundances and compositions that temporally correlate with estimates of global eustasy with rising sea level aragonite and acicular magnesium calcite precipitation gave way to the formation of equant calcite and possibly dolomite similarly the abundance of ooids was limited by positions of global sea level and associated changes in ocean chemistry modern abiotic marine carbonates also exhibit variable abundances and compositions as a function of changing fluid chemistry with latitude and depth chemical data on ambient marine waters suggest that carbonate ion concentrations and rates of precipitation presently control the nature of marine cement and ooids using data from modern oceans to calculate the requisite atmospheric pco 2 levels necessary to form this range of phases in ancient seas suggests that atmos

automicrite in a nummulite bank from the monte saraceno southern italy evidence for synsedimentary cementation following introduction of the term nummulite bank there has been debate regarding interpretation of these types of deposits as autochthonous automicrite or allochthonous detrital micrite these banks are made up of large foraminifera and ill defined fine grained components the fine grained components consist mainly of micrites the recognition of automicrite has deep implications for the synsedimentary cementation and stabilization of the bank in order to distinguish between automicrite and detrital micrite the nanomorphology geochemistry and organic matter remains in the microfacies of a nummulite bank in the middle eocene of monte saraceno gargano southern italy were analysed optical and scanning electron microscope investigations showed that the micrites have been recrystallized to aggrading microsparite epifluorescence observations on selected micrite microsparite areas with peloidal texture revealed the presence of organic matter scanning electron microscope analyses on epifluorescent micrites showed that the microbial peloids have smaller crystal sizes than those in organic matter depleted areas the geochemical characterization of extracted organic matter performed through the functional group analyses by fourier transform infrared spectroscopy shows strong prevalence of the aromatic fraction over the aliphatic and carboxylic ones these characteristics of organic compounds indicate both their thermal maturation and their likely derivation from degradation of bacterial communities the local presence of peloidal anti gravity textures bright epifluorescence and organic molecules in clotted peloidal areas suggest that the metabolic activity of microbial communities could have induced precipitation of these micrites and consequently the syndepositional cementation of the nummulite bank this type of cementation can rapidly stabilize sediments and promote the depositional bank geometry

geochemical evolution of the northern plains of mars early hydrosphere carbonate development and present morphology it is likely that early in mars history abundant liquid water was available under a thick several bars carbon dioxide atmosphere this water could have formed an ocean located primarily in the lowlands of the northern hemisphere an equilibrium geochemical model of this ocean and its interactions with the atmosphere and regolith of mars was developed and the results of this model were used to discuss the evolution of the volatile budget of mars including the deposition of large carbonate beds on the northern plains differential solutional weathering of these carbonate beds may have caused the formation of some of the enigmatic features seen on the northern plains of mars such as the thumbprint terrain and enclosed depressions

genesis of large siliceous stromatolites at frying pan lake waimangu geothermal field north island new zealand lilypad stromatolites up to 3 m long and 1ae5 m wide were found to be actively growing in the shallow marginal waters of frying pan lake and its outflow channel these stromatolites composed of phormidium 90 fischerella and a variety of other microbes develop through a series of distinct growth stages dark green microbial mats cover the floor of the outflow channel and give rise to columns of various sizes and shapes in the shallower marginal waters once the columns reach the water level the mats spread laterally to form a lilypad stromatolite the lilypads are characterized by a raised dark green rim 4 5 mm high that encircles a flat interior covered with a distinctive orange red mat the microbes forming the columns and lilypad plate are being actively silicified the stromatolites are formed of i flat lying phormidium filaments p laminae ii upright filaments of phormidium that are commonly associated with fischerella u laminae and iii mucus diatoms and pyrite framboids m laminae p laminae dominate most of the columns with tripartite cycles of p u to m laminae being found mostly in the upper parts of the stromatolites the transition from the p to u laminae is marked by a change in the growth pattern of the phormidium and branching of fischerella which was probably triggered by a change in environmental conditions in the frying pan lake outflow channel this change may be related to fluctuations in water level and flow rates that are caused by periods of heavy rain seasonal changes long term variations in rainfall and or the unique 40 day hydrological cycle that exists between frying pan lake and inferno crater which is a nearby hydrothermal crater lake

composition and syngeneity of molecular fossils from the 2 78 to 2 45 billion year old mount bruce supergroup pilbara craton western australia shales of very low metamorphic grade from the 2 78 to 2 45 billion year old ga mount bruce supergroup pilbara craton western australia were analyzed for solvent extractable hydrocarbons samples were collected from ten drill cores and two mines in a sampling area centered in the hamersley basin near wittenoom and ranging 200 km to the southeast 100 km to the southwest and 70 km to the northwest almost all analyzed kerogenous sedimentary rocks yielded solvent extractable organic matter concentrations of total saturated hydrocarbons were commonly in the range of 1 to 20 ppm g g rock but reached maximum values of 1000 ppm the abundance of aromatic hydrocarbons was 1 to 30 ppm analysis of the extracts by gas chromatography mass spectrometry gc ms and gc ms metastable reaction monitoring mrm revealed the presence of n alkanes mid and end branched monomethylalkanes cyclohexylalkanes acyclic isopre noids diamondoids tri to pentacyclic terpanes steranes aromatic steroids and polyaromatic hydrocarbons neither plant biomarkers nor hydrocarbon distributions indicative of phanerozoic contamination were de tected the host kerogens of the hydrocarbons were depleted in 13 c by 2 to 21 relative to n alkanes a pattern typical of although more extreme than other precambrian samples acyclic isoprenoids showed carbon isotopic depletion relative to n alkanes and concentrations of 2 methylhopanes were relatively high features rarely observed in the phanerozoic but characteristic of many other precambrian bitumens molecular parameters including sterane and hopane ratios at their apparent thermal maxima condensate like alkane profiles high mono and triaromatic steroid maturity parameters high methyladamantane and methyldiaman tane indices and high methylphenanthrene maturity ratios indicate thermal maturities in the wet gas gener ation zone additionally extracts from shales associated with iron ore deposits at tom price and newman have unusual polyaromatic hydrocarbon patterns indicative of pyrolytic dealkylation the saturated hydrocarbons and biomarkers in bitumens from the fortescue and hamersley groups are characterized as probably syngenetic with their archean host rock based on their typical precambrian molecular and isotopic composition extreme maturities that appear consistent with the thermal history of the host sediments the absence of biomarkers diagnostic of phanerozoic age the absence of younger petroleum source rocks in the basin and the wide geographic distribution of the samples aromatic hydrocarbons detected in shales associated with iron ore deposits at mt tom price and mt whaleback are characterized as clearly archean based on their hypermature composition and covalent bonding to kerogen copyright 2003 elsevier ltd

elf vlf recordings during the 11 march 2011 japanese tohoku earthquake 1 broadband elf vlf radio recordings 0 2 40 khz were made at a site in onagawa japan located 102 km from the epicenter of the m9 0 11 march 2011 earthquake the fifth most powerful earthquake in recorded history the receiver operated for about two minutes after the start of the earthquake after which the receiver lost power examination of the vlf data shows no radio emissions preceding or coincident with the onset of the earthquake however once the secondary seismic waves reached the receiver a number of impulses and diffuse noise bands arose which may result from the entire power grid shaking or from radio emissions from compressing rocks examination of the elf data 0 2 1 khz show no precursor effect in the hours preceding the earthquake examination of vlf data from narrowband transmitters shows no anomalous activity in the days or weeks preceding the earthquake our instrument low frequency cut off is 200 hz and thus we cannot comment on emissions in the ulf range 10 hz

nature of the crust in maine usa evidence from the sebago batholith neodymium and lead isotope and elemental data are presented for the sebago batholith 293 2 ma the largest exposed granite in new england the batholith is lithologically homogeneous yet internally heterogeneous with respect to rare earth elements ree and nd isotopic composition two mica granites in the southern central portion of the batholith group 1 are characterized by ree patterns with uniform shapes cen ybn chondrite normalized 9 4 19 and eu eu eu anomaly 0 27 0 42 and nd t 3 1 to 2 1 peripheral two mica granites group 2 spatially associated with stromatic and schlieric migmatites have a wider range of total ree contents and patterns with variable shapes cen ybn 6 1 67 eu eu 0 20 0 46 and nd t 5 6 to 2 8 the heterogeneous ree character of the group 2 granites records the effects of magmatic differentiation that involved monazite coarse grained leucogranites and aplites have kinked ree patterns and low total ree but have nd isotope systematics similar to group 2 granites with nd t 5 5 to 4 7 rare biotite granites have steep ree patterns cen ybn 51 61 eu eu 0 32 0 84 and nd t 4 6 to 3 8 the two mica granites have a restricted range in initial pb isotopic composition 206pb 204pb 18 41 18 75 207pb 204pb 15 60 15 68 208pb 204pb 38 21 38 55 requiring and old high u pb but not th u source component the nd isotope data are consistent with magma derivation from two sources avalon like crust nd 3 and central maine belt metasedimentary rocks nd 4 without material input from the mantle the variations in isotope systematics and ree patterns are inconsistent with models of disequilibrium melting which involved monazite

stromatolite assemblages of the late precambrian in china abstract the late precambrian as used in this paper is represented by the sections in the jixian chihsien and yangtze gorges these rocks correspond to the middle late proterozoic of some authors and range in age from c 1900 to 600 ma the succession can be subdivided into four systems the changcheng jixian qingbaikou and sinian systems all of which yield abundant stromatolites based on the latest studies we suggest a new sixfold classification scheme supertype type subtype family genus and species and refer the stromatolites to 13 families and 50 genera including some material published already in china the stromatolites of the late precambrian of china may be represented by elements from yanshan southern liaodong peninsula and kaiyang of guizhou etc they are subdivided into eight stromatolite assemblages and correlated throughout most of china

jarosite and hematite at meridiani planum from opportunity s mossbauer spectrometer mossbauer spectra measured by the opportunity rover revealed four mineralogical components in meridiani planum at eagle crater jarosite and hematite rich outcrop hematite rich soil olivine bearing basaltic soil and a pyroxene bearing basaltic rock bounce rock spherules interpreted to be concretions are hematite rich and dispersed throughout the outcrop hematitic soils both within and outside eagle crater are dominated by spherules and their fragments olivine bearing basaltic soil is present throughout the region bounce rock is probably an impact erratic because jarosite is a hydroxide sulfate mineral its presence at meridiani planum is mineralogical evidence for aqueous processes on mars probably under acid sulfate conditions

evidence for mg rich carbonates on mars from a 3 9 μm absorption feature abstract the origin and nature of the early atmosphere of mars is still debated the discovery of sulfate deposits on the surface coupled with the evidence that there are not large abundances of carbonates detectable on mars in the optically accessible part of the regolith leaves open different paleoclimatic evolutionary pathways even if carbonates are responsible for the feature observed by tes and mini tes at 6 76 m alternative hypotheses suggest that it could be due to the presence of hydrated iron sulfates his carbonates can be discerned from his by investigating the spectral region in which a strong overtone carbonate band is present the planetary fourier spectrometer on board the mars express spacecraft has acquired several thousand martian spectra in the range 1 2 45 m since january 2004 most of which show a weak absorption feature between 3 8 and 4 m a similar feature was observed previously from the earth but its origin could not be straightforwardly ascribed to surface materials and specifically to carbonates here we show the surficial nature of this band that can be ascribed to carbonate mixed with the martian soil materials the materials that best reproduce the detected feature are mg rich carbonates huntite camg3 co3 4 and or magnesite mgco3 the presence of carbonates is demonstrated in both bright and dark martian regions an evaluation of the likeliest abundance gives an upper limit of 10 wt the widespread distribution of carbonates supports scenarios that suggest carbonate formation occurred not by precipitation in a water rich environment but by weathering processes

mars surface diversity as revealed by the omega mars express observations the observatoire pour la mineralogie l eau les glaces et l activite omega investigation on board the european space agency mars express mission is mapping the surface composition of mars at a 0 3 to 5 kilometer resolution by means of visible near infrared hyperspectral reflectance imagery the data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy offering key insights into the evolution of mars omega has identified and mapped mafic iron bearing silicates of both the northern and southern crust localized concentrations of hydrated phyllosilicates and sulfates but no carbonates and ices and frosts with a water ice composition of the north polar perennial cap as for the south cap covered by a thin carbon dioxide ice veneer

regional geochemical and isotopic variations of northern new england plutons implications for magma sources and for grenville and avalon basement terrane boundaries examination of 36 devonian to pennsylvanian plutons within and bordering the central maine terrane of north central new england shows that the plutons display regional variations in mineral and bulk rock compositions and in oxygen and sulfur isotopic values these variations principally correspond to the regional structural trends of the central maine terrane plutons located on that terrane9s southeast flank adjacent to the massabesic gneiss complex on the terrane9s northwest flank adjacent to the bronson hill anticlinorium and in the northeastern part of the northeast kingdom batholith of vermont have biotites with relatively low al concentrations 3 0 cations p f u per formula unit feldspars with higher an contents up to an 55 and lower 18 o 7 9 and higher 34 s average of 0 bulk rock values compared to plutons within the central parts of the central maine terrane these characteristics are most compatible with metaigneous or metavolcaniclastic sources as shown by others the plutons of vermont and northwestern maine preserve grenvillian signatures whereas those of southeastern new hampshire specifically the granite at milford new hampshire and maine sebago phillips have avalonian signatures within the interior of the central maine terrane of new hampshire and western maine and in the connecticut valley trough of vermont are distinct regions characterized by peraluminous plutons with high 18 o values 11 low 34 s values 25 al rich biotites 3 3 cations p f u and an poor plagioclases 30 these data are most consistent with metasedimentary sources or at a minimum the plutons were heavily contaminated by central maine terrane or connecticut valley trough metasedimentary rocks these peraluminous plutons do not have the unique signatures of the underlying precambrian basements several metaluminous plutons in the central maine terrane along the new hampshire maine border separate two regions of peraluminous plutons these metaluminous plutons have biotite and isotopic compositions that are similar to those of the plutons along the flanks of the central maine terrane indicative of less paleozoic metasedimentary input compared to the peraluminous plutons in the interior of the central maine terrane the metaluminous plutons also have trace element characteristics identical to those of plutons in vermont and northwestern maine that have a known grenville basement terrane source we suggest that the metaluminous plutons also had sources in the underlying grenville basement and that the grenville avalon boundary cuts diagonally across northern new england because the plutons with grenvillian signatures are adjacent to plutons with avalonian signatures the sebago batholith and phillips pluton we suggest that there is no medial new england basement in this region of new england some peraluminous two mica plutons have trace element and stable isotopic characteristics that are compatible with partial melting of metasedimentary rocks the components of which were deposited in an anoxic basin such as the smalls falls formation of the central maine terrane but many other plutons have compositions that are inconsistent with this model we suggest that the compositions of many new hampshire plutonic suite plutons indicate greater heat input than that available from u enriched metasedimentary rocks and instead require emplacement of mafic magmas from the mantle or lower crust

origin and evolution of valleys on martian volcanoes morphological analyses of six martian volcanoes ceraunius tholus hecates tholus alba patera hadriaca patera apollinaris patera and tyrrhena patera indicate that fluvial processes were the dominant influence in the initiation and subsequent development of many dissecting valleys lava processes and possibly volcanic density flows were also important as valley forming processes fluvial valleys are especially well developed on alba patera ceraunius tholus and hecates tholus these valleys are inset into the surrounding landscape they formed in regions of subdued lava flow morphology contain tributaries and tend to widen slightly in the downstream direction lava channels on alba patera are located on the crest of lava flows and have a discontinuous irregular surface morphology and distributary patterns these channels sometimes narrow toward their termini possible volcanic density flow channels are located on the northern flank of ceraunius tholus valleys dissecting apollinaris patera hadriaca patera and tyrrhena patera appear to have a complex evolution probably a mixed fluvial and lava origin they are inset into a subdued possibly mantled surface lack tributaries and either have fairly constant widths or widen slightly downvalley valleys surrounding the caldera of apollinaris appear to have formed by fluvial and possibly by volcanic density flow processes while those on the apollinaris fan structure may have a mixed lava and fluvial origin valleys on tyrrhena have broad flat floors and theater heads which have been extensively enlarged probably by sapping hadriaca valleys have a trough shaped form like those on the fan structure on apollinaris but are more enlarged and have theater heads fluvial valleys on the martian volcanoes generally followed a two stage evolutionary sequence similar to that of the hawaiian volcano valleys including 1 initial formation by surface runoff and 2 subsequent enlargement by groundwater sapping because basalt is highly permeable valleys on hawaii island formed only in regions where lava flows were mantled by less permeable volcanic ash similarly fluvial valleys on the martian volcanoes particularly those on alba patera formed in regions where lava flow morphology is subdued probably by ash mantling thus the presence or absence of this mantling may explain why fluvial valleys are present on some martian volcanoes but not on others of the same age the formation of fluvial or fluvial modified valleys on the older volcanoes ceraunius hecates tyrrhena apollinaris and hadriaca implies that surface and near surface water activity was widespread during late noachian to early hesperian period of heavy bombardment however the presence of anomalously young fluvial valleys on alba patera indicates that fluvial valley activity did not entirely cease near the end of late heavy bombardment but rather persisted in isolated regions until mid to late amazonian

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

diverse aqueous environments on ancient mars revealed in the southern highlands high resolution spectral images reveal many new exposures of hydrated minerals across the noachian southern highlands of mars several different phyllosilicates are observed with inferred accompanying phases ranging from zeolites to sulfates to chlorides each in distinct geologic settings hydrated sulfates are observed in several locations at mid latitudes and likely formed independently from the equatorial sulfates these assemblages suggest a greater diversity of aqueous environments on ancient mars than has previously been recognized and their distribution implies that alteration was widespread during the noachian period not restricted to a few locations

study of terrestrial fossils in phyllosilicate rich soils implication in the search for biosignatures on mars abstract the search for biosignatures in the soil of mars is a major objective of the planet exploration but the detection of such structures is not straightforward due to the degradation of the organic material in a previous work our group has analyzed the spectral reaction to thermal processing of biomineral carbonate samples including fresh and fossil shells we found that two terrestrial fossil shells collected from clay deposits preserve their biomineral characteristics much better than coeval fossils not embedded in clay layers in the present paper we extend our analysis to a set of fossils found in three different terrestrial clay deposits our results confirm that the level of degradation may be much lower than the standard values if fossils are surrounded by clay minerals as a result these fossils have a spectroscopic response to thermal treatment which make them much more distinguishable from their abiotic counterparts than coeval fossils not collected from clay deposits this result implies that the phyllosilicates regions recently discovered on mars may represent very interesting environments that can provide conditions favorable to preserve evidence of biomarkers and hence can be regarded as good candidate locations for their detection

mineralogy at meridiani planum from the mini tes experiment on the opportunity rover the miniature thermal emission spectrometer mini tes on opportunity investigated the mineral abundances and compositions of outcrops rocks and soils at meridiani planum coarse crystalline hematite and olivine rich basaltic sands were observed as predicted from orbital tes spectroscopy outcrops of aqueous origin are composed of 15 to 35 by volume magnesium and calcium sulfates a high silica component modeled as a combination of glass feldspar and sheet silicates 20 to 30 and hematite only minor jarosite is identified in mini tes spectra mini tes spectra show only a hematite signature in the millimeter sized spherules basaltic materials have more plagioclase than pyroxene contain olivine and are similar in inferred mineral composition to basalt mapped from orbit bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites bright wind streak material matches global dust waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering

suspect terranes and accretionary history of the appalachian orogen the north american connection or the grenvillian continental crust that separated from eastern north america during the initiation of the appalachian orogenic cycle is poorly defined within the present orogen a variety of terranes occur outboard of the north american miogeocline all structurally uncoupled and therefore suspect stratigraphic analysis indicates that appalachian accretion progressed from the miogeocline outward the boundaries of the earliest accreted western terranes are marked by melange and ophiolite complexes later boundaries between eastern terranes are steep mylonitic zones and brittle faults accretionary events defined by stratigraphic analysis correspond to times of major deformation plutonism and metamorphism in the history of the orogen

molecular fossils and other organic markers as palaeoenvironmental indicators of the messinian calcare di base formation normal versus stressed marine deposition rossano basin northern calabria italy a multidisciplinary study has been carried out on the late miocene messinian calcare di base formation in northern calabria italy with the aim of understanding the depositional conditions of these enigmatic carbonate sediments that have been interpreted as evaporitic or diagenetic limestone the research has been developed through sedimentological microfacies organic petrography and geochemical analyses palynofacies rock eval pyrolysis and gas chromatography mass spectrometry the carbonates studied preserve their original mineralogy aragonite and microstructure the prevailing microfacies consists of clotted peloidal micrite with antigravitative fabric larger and darker cylindrical subcylindrical micritic grains attributable to faecal pellets are more or less randomly dispersed in the peloidal micrite the faecal pellets have been ascribed to copepods because zooclasts of these arthropods were observed in the palynofacies bright epifluorescence characterizes the faecal pellets and peloidal micrite indicating their high content of organic matter detrital and stromatolitic microfacies occur rarely around a few percent the detrital microfacies is characterized by silt sized grains organized in thin sometimes bioturbated graded laminae the stromatolitic microfacies shows planar to gently curved wrinkled laminae organized in dark and light couplets the associated sedimentary organic matter shows low maturity and preserves the original signatures of the source organisms rock eval pyrolysis revealed a transitional composition between type ii and type iii kerogen suggesting a mixture of marine and terrigenous organic matter input the molecular biogeochemical data indicate three main biological signatures algae bacteria and higher plants organic markers together with sedimentary evidence indicate a marine depositional scenario influenced by freshwater input rather than evaporitic concentration we conclude that the most probable bacterial process involved in carbonate precipitation of the calcare di base considering the freshwater input and consequent probable enrichment in organic matter and ca2 ions is ammonification of amino acids in aerobic conditions

the phillips pluton maine usa evidence of heterogeneous crustal sources and implications for granite ascent and emplacement mechanisms in convergent orogens the phillips pluton age of 403 8 1 3 ma was assembled at a crustal level below the contemporary brittle plastic transition during regional dextral reverse transpressive deformation the pluton is composed dominantly of medium to coarse grained leucogranite sensu lato s l but within its bounds includes decametric massive outcrop of fine to medium grained granodiorite s l in places the leucogranite contains centimetric enclaves apparently of the granodiorite granodiorite is host to more biotite than muscovite and more calcic oscillatory zoned plagioclase compared to the leucogranite pegmatitic granite and composite pegmatite aplite occur as metric sheets within the pluton and as larger bodies outside the pluton to the sw magmatic fabrics defined by biotite schlieren occur locally in the leucogranite the attitude of these fabrics and layering within the leucogranite are concordant with the ne striking steeply dipping country rock foliation k2o contents rb sr ratios rb sr and ba covariations and chondrite normalized rare earth element ree patterns of leucogranite are consistent with high to moderate a h2o muscovite dehydration equilibrium eutectic melting of a predominantly pelite source similar to metasedimentary rocks of the surrounding central maine belt cmb the ree patterns and rb sr ratios of granodiorite also suggest derivation from a metasedimentary source but more likely by moderate to low a h2o muscovite biotite dehydration equilibrium eutectic to non eutectic minimum melting of a protolith dominated by greywacke in which garnet and plagioclase were residual phases both granite s l types have heterogeneous initial nd isotope compositions samples of granodiorite define a range in end 404 ma of 1 8 to 0 1 0 3 2 uncertainty and samples of leucogranite define a range in end 404 ma of 8 0 to 5 3 0 3 2 uncertainty this bimodal distribution suggests that melts were derived from a minimum of two sources the data are consistent with these sources being cmb metasedimentary rocks end 404 ma 4 for the granodiorite the range of nd isotope compositions within each granite type most likely reflects isotopic heterogeneity inherited from the source these data imply that the integrity of individual melt batches was maintained during ascent and that extensive mixing of melt batches during emplacement at this level in the pluton did not occur although centimetric enclaves have intermediate nd isotope compositions consistent with small scale interactions between magmas we infer that the phillips pluton represents the root of a larger pluton and that what remains of this larger pluton is the feeder constructed from multiple melt batches arrested during waning flow of granite magma through a crustal scale shear zone system

infrared spectroscopy of microbially induced carbonates and past life on mars abstract a number of evidences as the past presence of water a denser atmosphere and a mild climate suggest that on early mars environmental conditions should have been favourable to the emergence of life therefore if life actually developed on mars a few hundreds of million years ago or even more recently some biomarkers may still be present in several previous papers based on laboratory analysis we have investigated the modifications induced by thermal processing in the mid infrared spectra of carbonate samples in the form of fresh shells and fossils of different ages skeletal remains of already complex terrestrial life whose biotic origin is not questionable in this way we have been able to develop a spectroscopic method for discriminating biotic samples from their abiotic counterparts in this work we show that our method can be successfully applied also to microbialites i e bio induced carbonates deposits and particularly to stromatolites the laminated fabric of microbialites some of which are among the most primitive and oldest traces of biological activity on earth this result is of valuable importance since such primitive living organisms can be considered good analogues for putative martian life forms

phyllosilicates in the mawrth vallis region of mars 1 omega mars express has discovered large outcrops rich in phyllosilicates in the region of mawrth vallis mars around 20 w 25 n the region is located in noachian highly cratered terrains close to the limit of the martian dichotomy where the outflow channel mawrth vallis cuts the highlands we have examined this region using omega spectra of the surface from 0 9 m to 2 6 m with spatial sampling from 500 m to 3 km offering a full coverage of the region omega spectra show two broad bands centered at 1 m and 2 2 m revealing the presence of clinopyroxene on dark surfaces phyllosilicates have been identified by absorption bands at 1 4 m 1 9 m and 2 2 or 2 3 m comparison with laboratory spectra reveals similarities with al oh smectites such as montmorillonites or fe or mg oh smectites such as nontronite a precise location of the phyllosilicate rich areas on visible hrsc images indicates that they are placed exclusively on bright outcrops mostly on the plateaus dated to the noachian period on hrsc and moc images the phyllosilicate rich outcrops reveal strong erosional features such as numerous residual buttes composed of layers a few meters thick the phyllosilicate rich unit corresponds to a geological unit more than 100 m thick over a horizontal extension approximately of 300 km 400 km this unit implies a large volume of altered rocks either in situ or after transport and deposition in noachian terrains revealing a different climatic and geologic environment from the present one

the acadian thermal history of the merrimack synclinorium in new hampshire the acadian structural history of the merrimack synclinorium involves a phase of nappe emplacement and thrusting at 400 m y b p followed by a second thickening event before 370 m y b p at the end of this phase the present erosion surface was buried at pressures of 6 to 8 kbar and subsequently experienced peak metamorphic temperatures in the range of 500 c to 650 c the thermal history of the acadian metamor phism of the merrimack synclinorium is examined in a well studied area of central new hampshire to determine the conditions required for the high grade metamorphism of the region constraints are provided by metamorphic pressure estimates by information on the erosional history and by present day heat flow determinations in the synclinorium one dimensional heat transfer calculations show that the high grade metamorphism could readily have been produced during thermal relaxation of the thickened continental crust under conditions of normal continental heat flow these conditions also permit the me

lead isotopic evidence for distinct sources of granite and for distinct basements in the northern appalachians maine lead isotopic compositions of feldspars in plutons of the coastal lithotectonic block avalonian basement central maine merrimack synclinorium and connecticut valley gaspe synclinorium in northern maine granville basement indicate the presence of three fundamentally different sources of devonian granitic rocks in maine plutons in the coastal lithotectonic block have the most radiogenic values 206 pb 204 pb 18 25 19 25 207 pb 204 pb 15 59 15 67 208 pb 204 pb 38 00 38 60 plutons in northern maine are the least radiogenic 206 pb 204 pb 18 00 18 50 207 pb 204 pb 15 51 15 55 and 208 pb 204 pb 37 80 38 38 intermediate lead isotope values characterize the plutons in central maine 206 pb 204 pb 18 20 18 40 207 pb 204 pb 15 56 15 60 and 208 pb 204 pb 38 00 38 30 all plutons show relatively radiogenic lead values for their ages and suggest the imprint of continental crustal sources especially in the coastal block and in central maine plutons from the connecticut valley gaspe synclinorium allow for a more significant isotopic input from the subcontinental mantle the three distinct lead isotope groups probably identify plutons formed in different crustal fragments in a continental collisional environment that were juxtaposed after emplacement of the granites

distribution classification and ages of martian impact crater lakes paleolakes in impact craters on mars are characterized at global scale using the viking orbiter data we identified 179 paleolakes in impact structures formed by the influx of water and sediment derived from valley networks and channels that can be classified into three different fluviolacustrine systems closed open and lake chain systems we show the hydrogeologic implications for each of the three systems and their significance in terms of duration of fluviolacustrine activity this study provides a catalog of areographic physical and physiographic data for each of the studied impact crater lakes associated with the description of the sedimentary structures observed it also identifies environments where life and or precursors to life could have found favorable conditions to evolve