tertiary extensional faulting and evolving ductile brittle transition zones in the northern snake range and vicinity new insights from seismic data new geologic mapping and high resolution seismic data from east central nevada shed light on the evolution of the northern snake range decollement nsrd and its relation to the present basins and ranges we suggest that the nsrd originated in oligocene time as a flat 20 km wide 7 km deep zone of decoupling between localized ductile stretching below and more widely distributed high angle normal faulting above younger east dipping normal faults cut the western part of the nsrd forming the tilted fault blocks and highly asymmetric grabens that constitute the duck creek range duck creek valley and schell creek range spring valley and folded the nsrd to its present antiformal geometry these youngest faults flatten into pervasive subhorizontal reflectors at a depth of 10 to 15 km that we interpret as the youngest ductile brittle transition

localization of listric faults at thrust fault ramps beneath the great salt lake basin utah evidence from seismic imaging and finite element modeling reflection seismic data from the great salt lake basin utah show that the major basin bounding normal faults decrease in dip from 60 at the surface to 10 20 at depths as shallow as 4 6 km this rapid decrease in fault dip at depths shallower than the brittle ductile transition zone in the basin and range province suggests an explanation other than a gradual change of rheology and stress orientations with depth using a dense grid of seismic data gravity data borehole data and published geologic information from islands in the lake we constrain the position of the sevier age willard thrust and a footwall imbricate and show their reactivation as normal faults during tertiary extension in the absence of surface geologic information we use available subsurface information from the lake to draw an analogy with the ogden duplex in the wasatch front where cenozoic normal faulting was superimposed on an earlier sevier age thrust regime to give rise to listric normal faults our interpretations are consistent with finite element modeling results which demonstrate that extensional slip on preexisting thrust ramps leads to the formation of energetically favored synthetic normal faults some of which may merge with the thrust ramp and obtain listric geometries further slip on these listric faults gives rise to secondary synthetic and antithetic faults resulting in hanging wall grabens

clyde field growth fault secondary detachment above basement faults in north sea the clyde oil field in the southern north sea comprises a jurassic fulmar sand reservoir developed on a fault bounded terrace on the margin of the central graben palinspastic sections were constructed to honor seismic and well data and were repeatedly tested using new techniques for balancing structural sections in extensional regimes cross sectional area and bed length balance clearly demonstrate the presence of both shallow and deep fault detachments seismic remapping has substantiated this model and demonstrates the decoupling of the basement and shallow listric fault sets the new model has significance in terms of variations in reservoir quality and possible reservoir discontinuities resulting from fault seals of regional interest is the possibility of additio al growth fault plays of this type within the north sea basin

intraplate extensional tectonics of the eastern basin range inferences on structural style from seismic reflection data regional tectonics and thermal mechanical models of brittle ductile deformation the general lack of a correlation between earthquakes and surface faulting in the interior of the western u s cordillera has motivated our efforts to evaluate the geometry structural style and mechanism of normal faulting characteristic of this region of intraplate extension to address the problem we have interpreted over 1500 km of seismic reflection data and constructed detailed cross sections of the upper crust rheological models of the continental crust were calculated to examine the possibility of shallow quasi plastic flow and its influence on faulting in the eastern basin range the western colorado plateau and the middle rocky mountains our data and interpretations have revealed the following styles of cenozoic deformation 1 steep to low angle dip normal faulting along the wasatch fault 2 low angle dip and listric normal faulting possibly associated with movement on preexisting thrusts 3 the occurrence of asymmetric mostly eastward tilted tertiary basins that are bounded by low to moderate dipping planar and listric faults and 4 at least three vertically stacked en echelon low angle reflections in the mid to upper crust that dip gently westward from 3 km beneath the wasatch plateau to over 15 km at the utah nevada border these reflections are interpreted as normal detachment faults the structural style of the pervasive low to moderate angle dipping faults cannot be easily reconciled with classic brittle failure theory but the interpreted termination of normal faults at or above the deeper low angle reflections suggests the presence of shallow zones of ductile deformation that may have accommodated slip an important observation based on interpretations of seismic reflection profiles is that normal fault zones dip more gently in the subsurface than their associated scarps in unconsolidated surficial deposits segment boundaries of the wasatch fault zone apparently coincide with the positions of east trending displacement transfer structures in thrust sheets and the position of the precambrian uinta aulacogen suggesting that preexisting crustal structure partly controls the geometry of extension to examine the influence of ductile deformation quasi plastic flow was modeled for appropriate geotherms of the basin range and colorado plateau crusts these models provide constraints on the depth to the frictional quasi plastic transition that occurs as shallow as 8 km in the eastern basin range this depth also corresponds to the approximate depth above which most accurately determined earthquake foci for small earthquakes m 5 5 appear to nucleate at 10 15 km in or near the brittle ductile transition the rheological modeling suggests that a thermally deforming continental lithosphere plays an important role in the evolution of this extending intraplate region large scale low angle reflections may represent decollements and normal faults at the top of upper crustal zones of reduced shearing strength and higher ductility

structural analysis using thrust fault hanging wall sequence diagrams ogden duplex wasatch range utah detailed mapping and cross section traverses provide the control for structural analysis and geometric modeling of the ogden duplex a complex thrust system exposed in the wasatch mountains east of ogden utah the structures consist of east dipping folded thrust faults basement cored horses lateral ramps and folds and tear faults the sequence of thrusting determined by means of lateral overlap of horses thrust splay relationships and a top to bottom piggyback development is willard thrust ogden thrust weber thrust and taylor thrust major decollement zones occur in the cambrian shales and limestones the tintic quartzite is the marker for determining gross geometries of horses this exposed duplex serves as a good model to illustrate the method of constructing hanging wall sequence diagram a series of longitudinal cross sections that move forward in time and space and show how a thrust system formed as it moved updip over various footwall ramps a hanging wall sequence diagram also shows the complex lateral variations in a thrust system and helps to locate lateral ramps lateral folds tear faults and other features not shown on dip oriented cross sections

seismic reflection evidence for seismogenic low angle faulting in southeastern arizona focal mechanisms for large m 6 earthquakes in extensional terranes suggest that seismogenic normal faults have dips that range from approximately 30 degree to approximately 70 degree geologic relations suggest that low angle faults have accommodated large scale upper crustal extension these disparate observations are often reconciled by arguments that low angle faults move aseismically or rotate to low angles from initially high angles seismic reflection data from the tucson basin in southeast arizona image a low angle normal fault the santa rita fault that crops out along the trend of late quaternary fault scarps caused by large magnitude m approximately 6 7 7 6 earthquakes velocity independent dip analysis from shot records of the santa rita fault indicates that it has a true dip of approximately 20 degree to a depth of at least 6km this observation suggests that low angle extensional faults indeed may be seismogenic and that actual mechanisms for accommodation of upper crustal extension depend on local conditions of stress and preexisting geologic structure

active normal faulting and crustal extension a world wide review of fault plane solutions and focal depths for large normal faulting earthquakes on the continents shows that the overwhelming majority of such earthquakes nucleate in the depth range 6 15 km on faults dipping between 30 and 60 in the few cases where levelling or seismic data are good enough these normal faults are shown to be approximately planar from the surface to their nucleation depth at the base of the brittle crust there is evidence that in some cases as a result of the enormous transitory increase in strain rate during large earthquakes rupture continues into the normally ductile lower crust on surfaces with substantially gentler dips these low angle surfaces may be analogous to some of the detachments seen in metamorphic core complexes of the western usa but the nature of the motion on them depends on strain rate as well as on rheological contrasts between the detachments and the blocks on either side such contrasts however are unlikely to introduce substantial curvature to an originally planar shear zone if the observed spread in active normal fault dips is caused by rotation of the faults and the blocks they bound during extension then a maximum value of 1 7 can be accommodated by seismic activity on a single generation of normal faults with continued extension either a new generation of steeper faults cutting the rotated first faults is likely to form or the deformation will continue aseismically on faults dipping at less than 30 large earthquakes have not been observed to nucleate on very low angle 20 normal faults within the continental crust anywhere in the world such faults can of course move aseismically but are unlikely to do so on a large scale within the upper crust in areas where steep normal faults are seismically active thus extensional models that require concentrated simple shear on large sub horizontal faults within the brittle upper crust will also require a spatial separation between aseismic very low angle faulting and seismic highangle faulting since seismogenic high angle faults dominate the topography of extending regions upper crustal very low angle faulting if it occurs on a large scale presumably does so in areas that are relatively fiat

structure composition and location of organic matter in the enstatite chondrite sahara 97096 eh3 the insoluble organic matter iom of an unequilibrated enstatite chondrite sahara sah 97096 has been investigated using a battery of analytical techniques as the enstatitechondrites are thought to have formed in a reduced environment at higher temperatures thancarbonaceous chondrites they constitute an interesting comparative material to test theheterogeneities of the iom in the solar system and to constrain the processes that could affectiom during solar system evolution the sah 97096 iom is found in situ as submicrometergrains in the network of fine grained matrix occurring mostly around chondrules and asinclusions in metallic nodules where the carbonaceous matter appears to be moregraphitized iom in these two settings has very similar d15n and d13c this supports the ideathat graphitized inclusions in metal could be formed by metal catalytic graphitization ofmatrix iom a detailed comparison between the iom extracted from a fresh part and aterrestrially weathered part of sah 97096 shows the similarity between both iom samples inspite of the high degree of mineral alteration in the latter the isolated iom exhibits aheterogeneous polyaromatic macromolecular structure sometimes highly graphitized withoutany detectable free radicals and deuterium heterogeneity and having mean h and n isotopiccompositions in the range of values observed for carbonaceous chondrites it contains somesubmicrometer sized areas highly enriched in 15n d15n up to 1600 these observationsreinforce the idea that the iom found in carbonaceous chondrites is a common componentwidespread in the solar system most of the features of sah 97096 iom could be explainedby the thermal modification of this main component

diradicaloids in the insoluble organic matter from the tagish lake meteorite comparison with the orgueil and murchison meteorites the radicals in the insoluble organic matter iom from the tagish lake meteorite were studied by electron paramagnetic resonance and compared to those existing in the orgueil and murchison meteorites as in the orgueil and murchison meteorites the radicals in the tagish lake meteorite are heterogeneously distributed and comprise a substantial amount 42 of species with a thermally accessible triplet state and with the same singlet triplet gap e 0 1 ev as in the orgueil and murchison meteorites these species were identified as diradicaloid moieties the existence of similar diradicaloid moieties in three different carbonaceous chondrites but not in terrestrial iom strongly suggests that these moieties could be fingerprints of the extraterrestrial origin of meteoritic iom and markers of its synthetic pathway before its inclusion into a parent body

the geometrical evolution of normal fault systems abstract the purpose of this paper is to examine the kinematic behaviour of normal fault systems and see what general conditions govern their geometrical evolution we pay particular attention to seismological and surface data from regions of present day active normal faulting as the instantaneous three dimensional geometry at the time of fault movement is better known in active regions than in areas where the faults are now static most normal faults are concave upward or listric this shape can be produced by geometric constraints either because the faults reactivate curved thrusts or because they must be curved to accommodate rotations another effect which will produce curved faults is the variation of rheology with depth brittle failure at shallow depths produces less fault rotation than does distributed creep in the lower part of the crust an important geometric feature of normal faulting is the uplift of the footwall the amount of such uplift is related not only to the elastic properties of the lithosphere but also to the throw and dip of the fault a striking feature of active normal faults is that they occur in groups in which all the faults dip in the same direction this behaviour arises because the faults cannot intersect if they do one must cease to be active the rotation which such fault systems produce reduces the dip of the faults until a new steeply dipping fault is formed once a new fault cuts pre existing faults the earlier faults become locked and a new set of faults must propagate rapidly across the whole region involved many of these geometric constraints also apply to thrust faulting

prebiotic carbon in clays from orgueil and ivuna ci and tagish lake c2 ungrouped meteorites transmission electron microscopic tem and electron energy loss spectroscopic eels study of the ivuna and orgueil ci and tagish lake c2 ungrouped carbonaceous chondrite meteorites shows two types of c clay assemblages the first is coarser grained to 1 m clay flakes that show an intense o k edge from the silicate together with a prominent c k edge but without discrete c particles nitrogen is common in some clay flakes individual orgueil and tagish lake meteorite clay flakes contain up to 6 and 8 at c respectively the c k edge spectra from the clays show fine structure revealing aromatic aliphatic carboxylic and carbonate c the eels data shows that this c is intercalated with the clay flakes the second c clay association occurs as poorly crystalline to amorphous material occurring as nanometer aggregates of c clay and fe o rich material some aggregates are dominated by carbonaceous particles that are structurally and chemically similar to the acid insoluble organic matter the c k edge shape from this c resembles that of amorphous c but lacking the distinct peaks corresponding to aliphatic carboxylic and carbonate c groups nanodiamonds are locally abundant in some carbonaceous particles the abundance of c in the clays suggest that molecular speciation in the carbonaceous chondrites is partly determined by the effects of aqueous processing on the meteorite parent bodies and that clays played an important role this intricate c clay association lends credence to the proposal that minerals were important in the prebiotic chemical evolution of the early solar system

deuterium enrichments in chondritic macromolecular material implications for the origin and evolution of organics water and asteroids here we report the elemental and isotopic compositions of the insoluble organic material iom isolated from several previously unanalyzed meteorites as well as the reanalyses of h isotopic compositions of some previously measured samples alexander et al 2007 the iom in ordinary chondrites ocs has very large d enrichments that increase with increasing metamorphism and decreasing h c the most extreme d value measured being almost 12 000 we propose that such large isotopic fractionations could be produced in the oc parent bodies through the loss of isotopically very light h2 generated when fe was oxidized by water at low temperatures 200 c we suggest that similar isotopic fractionations were not generated in the iom of cv and co chondrites with similar metamorphic grades and iom h c ratios because proportionately less water was consumed during metamorphism and the remaining water buffered the h isotopic composition of the iom even a h was being lost from it hydrogen would also have been generated during the alteration of ci cm and cr carbonaceous chondrites the iom in these meteorites exhibit a considerable range in isotopic compositions but all are enriched in d as well as 15n relative to terrestrial values we explore whether these enrichments could also have been produced by the loss of h2 but conclude that the most isotopically anomalous iom compositions in meteorites from these groups are probably closest to their primordial values the less isotopically anomalous iom has probably been modified by parent body processes the response of iom to these processes was complex and varied presumably reflecting differences in conditions within and between parent bodies the d enrichments associated with h2 generation along with exchange between d rich iom and water in the parent bodies means that it is unlikely that any chondrites retain the primordial h isotopic composition of the water ice that they accreted the h isotopic compositions of the most water rich chondrites the cms and cis are probably the least modified and their compositions d 25 suggest that their water did not form at large radial distances from the sun where ice is predicted to be very d rich yet models to explain the o isotopic composition of inner solar system bodies require that large amounts of ice were transported from the outer to the inner solar system

the origin and evolution of chondrites recorded in the elemental and isotopic compositions of their macromolecular organic matter extraterrestrial organic matter in meteorites potentially retains a unique record of synthesis and chemical thermal modification by parent body nebular and even presolar processes in a survey of the elemental and isotopic compositions of insoluble organic matter iom from 75 carbonaceous ordinary and enstatite chondrites we find dramatic variations within and between chondrite classes there is no evidence that these variations correlate with the time and or location of chondrite formation or with any primary petrologic or bulk compositional features that are associated with nebular processes e g chondrule and volatile trace element abundances nor is there evidence for the formation of the iom by fischer tropsch type synthesis in the nebula or in the parent bodies the elemental variations are consistent with thermal maturation and or oxidation of a common precursor for reasons that are unclear there are large variations in isotopic composition within and between chondrite classes that do not correlate in a simple way with elemental composition or petrologic type nevertheless because of the pattern of elemental variations with petrologic type and the lack of any correlation with the primary features of the chondrite classes at present the most likely explanation is that all iom compositional variations are the result of parent body processing of a common precursor if correct the range of isotopic compositions within and between chondrite classes implies that the iom is composed of several isotopically distinct components whose relative stability varied with parent body conditions the most primitive iom is found in the cr chondrites and bells cm2 isotopically the iom from these meteorites resembles the iom in interplanetary dust particles chemically their iom resembles the chon particles of comet halley despite the large isotopic anomalies in the iom from these meteorites it is uncertain whether the iom formed in the interstellar medium or the outer solar system although the former is preferred here

precursor and metamorphic condition effects on raman spectra of poorly ordered carbonaceous matter in chondrites and coals abstract geothermometers based on raman spectrometry of carbonaceous matter and covering a wide range of temperatures 100 650 c have been developed over recent years while raman data have been largely interpreted in terms of temperature they are also the fingerprint of certain metamorphic conditions especially in the low temperature range relevant to poorly ordered carbonaceous matter this study investigates the raman spectra of two series of chondritic carbonaceous matter and coal samples formed from different precursors and under different metamorphic conditions the raman spectra of polyaromatic carbonaceous matter pcm from 42 chondrites and 27 coal samples measured with visible 514 nm and ultra violet 244 nm excitation wavelengths are analyzed the raman spectra of low rank coals and chondrites of petrologic types 1 and 2 which contain the more disordered pcm reflect the distinct carbon structures of their precursors the 514 nm raman spectra of high rank coals and chondrites of petrologic type 3 exhibit continuous and systematic spectral differences reflecting different carbon structures present during the metamorphism event they result from differences in the chemical structures of the precursors concerning for instance the reticulation of polyaromatic units or an abundance of ether functional groups or possibly from a lack of carbonization processes to efficiently expel oxygen heteroatoms due to weak lithostatic pressure and confinement these results suggest that the use of low temperature carbon thermometers should be restricted to a given geological context at the same time the sensitivity of raman spectra to precursors and certain metamorphic conditions could be used to obtain information other than temperature the analysis also provides evidence of the accretion of relatively homogeneous pcm precursors among ordinary co and cv carbonaceous chondrite parent bodies given that the 514 nm raman spectra of pcm efficiently trace the metamorphism grades looking closer however the 514 nm raman data are more scattered in chondrites than in coals and the maturity tracers are less sensitive and miscorrelate with the atomic h c ratio suggesting slight compositional and structural differences among the pcm precursors accreted

extraterrestrial organic matter preserved in 3 33 ga sediments from barberton south africa electron paramagnetic resonance epr analysis of carbonaceous volcanic tidal sediments from the 3 33 ga old josefsdal chert kromberg formation barberton greenstone belt documents the presence of two types of insoluble organic matter iom 1 iom similar to that previously found in archean cherts from numerous other sedimentary rocks in the world and of purported biogenic origin 2 anomalous iom localized in a 2 mm thick sedimentary horizon detailed analysis by continuous wave epr and pulse epr reveals that iom in this layer is similar to the insoluble component of the hydrogenated organic matter in carbonaceous chondrites suggesting that this narrow sedimentary horizon has preserved organic matter of extraterrestrial origin this conclusion is supported by the presence in this thin layer of another anomalous epr signal at g 3 attributed to ni cr al ferrite spinel nanoparticles which are known to form during atmospheric entry of cosmic objects from this epr analysis it was deduced that the anomalous sedimentary layer originates from deposition in a nearshore environment of a cloud of tiny dust particles originating from a flux of micrometeorites falling through the oxygen poor archean atmosphere

balanced cross section construction from seismic sections in areas of extensional tectonics abstract the application of the technique of balanced section construction initially developed for areas of compressional folding and faulting is reviewed with reference to extensional tectonics a number of examples are discussed where these techniques have been successfully applied in the north sea the interpretation of geoseismic sections is considered to be greatly assisted by careful application of geometrical balance and a consideration of strain even in areas of low crustal extensions the nature of seismic sections however places limitations on the validity of balancing which must be borne in mind with such interpretations and wherever possible the balancing of a geoseismic section should be confirmed by complete depth conversion the rapid testing of the integrity of the geoseismic section by attempting to balance the section at the interpretational phase can eliminate many problems as well as allowing the fullest use to be made of the geophysical information

cross section restoration and balancing as aid to seismic interpretation in extensional terranes structural cross sections in extensional terranes can be improved significantly by restoration and balancing principles originally developed for fold and thrust belts in rift basins and passive continental margins use of restoration techniques in analysis of growth faults elongate salt swells and other extensional structures results in geologically valid seismic interpretations sections must be in depth as opposed to two way time and oriented in the direction of material transport and decompaction must accompany restoration hanging wall deformation is characterized by different processes depending on the mechanical properties of the rocks being extended and can be approximated by various geometric and kinematic models antithetic faulting is analogous to antithetic shear combined antithetic and synthetic faulting is approximated by vertical shear domino style extension corresponds to rigid body rotation and flexural slip flow is modeled by bed length balance methods selection of the appropriate algorithm is crucial for proper restoration and balancing applications of these techniques illustrated here using seismic data from the gulf coast and north sea include 1 evaluating and adjusting seismic interpretations 2 projecting listric fault trajectories to depth 3 delineating more accurately the geometry and extent of hydrocarbon reservoirs 4 identifying new exploration leads 5 determining the deformation history of an area and 6 constraining the timing and direction of hydrocarbon migration and entrapment

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

nanosized carbon rich grains in carbonaceous chondrite meteorites abstract macromolecular carbonaceous material is common in primitive meteorites little information exists on its form and composition and there are no published data on nanometer scale chemical and structural variations transmission electron microscopy tem studies of cm meteorites reveal abundant previously unrecognized nanosized carbonaceous grains they have a high aromatic component as revealed by electron energy loss spectroscopy eels with up to 20 at substituted by s n and o they occur as discrete hollow and solid nanospheres and sparse nanotubes the grains exhibit considerable variations in composition size morphology and abundance among meteorites and may represent materials from multiple reservoirs

interlayer trapping of noble gases in insoluble organic matter of primitive meteorites abstract noble gases in primitive meteorites are trapped in a residue left after demineralization of bulk meteorite by hf and hcl most of the primordial ar kr and xe and small amounts of he and ne are removed by oxidation of this acid resistant residue e g with hno3 these gases referred as p1 are trapped in a poorly characterized presumably organic phase labeled phase q in order to understand the siting of p1 noble gases we have performed a solvation experiment on insoluble organic matter of orgueil ci pyridine was used because it presents an important swelling ratio of about 2 potentially able to change considerably the structure of phase q without affecting the crystalline structure of nanodiamonds chromite spinel and metal alloys present in acid residue heavy noble gases are largely lost upon pyridine treatment at room temperature however the elemental pattern of the remaining ar kr and xe is not different from that of the starting acid residue showing similar losses of all the heavy noble gases during solvation xenon stepwise heating data and deconvolution of different components based on isotopic ratios show that xe p1 is mainly affected by loss 60 following by xe p3 25 and xe hl 12 the xenon release is maximum at temperatures 1300 c 70 80 whereas only 23 is lost at 1600 c and no further loss occurs at 2100 c these results suggest the existence of at least two substructures in phase q with xe p1 being trapped preferentially in the less retentive phase as macromolecular organic matter is the only phase of acid residue sensitive to solvation this study demonstrates the organic nature of phase q the behavior of heavy noble gases upon pyridine solvation supports interlayer trapping of these elements probably within organic layers of aromatic moieties linked by short aliphatic chains

solid state cp mas 13 c nmr of the insoluble organic matter of the orgueil and murchison meteorites quantitative study solid state cp mas 13c nuclear magnetic resonance nmr study of the insoluble organic fraction isolated by hf hcl treatment under an inert atmosphere from the orgueil and murchison carbonaceous meteorites is reported based on these spectra eight different types of carbons aro and ali linked ch3 ch2 aliphatic c linked to heteroelements protonated and non protonated aromatic c carboxyls and carbonyls were identified their relative amounts were determined and theoretical nmr derived h c atomic ratios were calculated comparison of these h c ratios with those obtained from elemental analysis revealed that a large part of the carbons of the insoluble fraction of both meteorites are not detected by cp mas 13c nmr taking into account these undetected carbons the relative abundance of aromatic carbons as of the total carbons was calculated as between 69 and 78 in orgueil and 61 and 67 in murchison and thus shown to be much higher than previously thought in addition the nmr data allowed to calculate the ratio of non protonated and protonated aromatic carbons based on previous studies on chemical and thermal degradation the present nmr data were interpreted as reflecting the occurrence of highly substituted rather small aromatic moieties in these insoluble organic materials along with ftir data nmr results also pointed to a relatively high branching level in the aliphatic chains especially for murchison according to the above results the insoluble organic matter in these meteorites did not suffer a marked thermal maturation during the late hydrothermalism of the parent body its synthesis involved a statistical combination of all the possible bonds between ch3 ch2 and ch radicals producing both the aliphatic and the aromatic moieties this model explains not only the chemical features of the chondritic insoluble organic material but also the typical ftir signature of the interstellar medium therefore organic material found in the interstellar medium and that incorporated in the most primitive objects of the solar system seem to share a common organosynthesis

extensional reactivation of thrust faults accompanied by coseismic surface rupture southwestern wyoming and north central utah extensional reactivation of thrust faults north of the uinta mountains in utah and wyoming is accompanied by quaternary surface faulting tilting and monoclinal folding the 40 km long bear river fault zone consists of down to the west right stepping en echelon scarps each about 3 0 to 3 5 km in length striking n20 w to n20 e scarp derived colluvial deposits record two holocene surface ruptures with net vertical tectonic displacements ranging from 5 m per event west 1989 in press radiocarbon ages indicate surface faulting events occurred at about 4 6 ka and 2 4 ka the length of surface rupture and net slip per event in the bear river fault zone imply a seismic potential comparable to the lost river fault hebgen lake fault and the wasatch fault zone a late quaternary normal scarp is also coincident with the leading edge of the absaroka thrust fault 7 2 km west of the bear river fault zone scarp derived colluvial deposits record one surface faulting event over a length of at least 5 0 km the age of surface rupture is coeval with the bear river fault zone 2 4 ka normal faults displacing pleistocene surfaces deposits and tectonic tilt indicate that the hogsback thrust east of the bear river fault zone was reactivated in a normal sense but now may be inactive due to subsequent development of the bear river fault zone cumulative normal throw of 200 m on the hogsback fault may be responsible for postulated tectonic separation of the bear river and green river drainage basins neotectonic deformation results from east west extension superposed on the hogsback and absaroka thrust plates extensional reactivation of thrust faults caused propagation of new normal faults over stress points particularly at the hogsback ramp to flat transition and at the thrust leading edges the ages of surface rupture and cumulative throws indicate normal reactivation of the hogsback and absaroka thrusts and propagation of the intervening bear river fault zone proceeded from east to west opposite initial development of the thrusts in late cretaceous to paleocene time normally reactivated thrust faults and propagation of listric normal faults accompanied by surface rupture have significant implications for the tectonic seismogenic development of the eastern basin and range transition zone

high resolution tem of chondritic carbonaceous matter metamorphic evolution and heterogeneity the insoluble carbonaceous matter from 12 chondrites ci cm co cv eh and uoc was characterized by high resolution transmission electron microscopy hrtem besides ubiquitous nanoglobules the insoluble organic matter from petrologic type 1 and 2 chondrites and semarkona ll 3 0 is composed of a highly disordered polyaromatic component no structural differences were observed between these ioms in agreement with the limited thermal metamorphism they all experienced in chondrites of petrologic type 3 0 the evolution of the iom is controlled by the extent of thermal metamorphism the polyaromatic layers shorter than 1 nm in petrologic type 3 0 chondrites grow up to sizes between 5 and 10 nm in petrologic type 3 6 chondrites contributing to the increase of the degree of structural order in addition we find rare but ubiquitous onion like carbons which may be the product of nanodiamond graphitization the insoluble carbonaceous matter of the enstatite chondrite sahara 97096 eh 3 is different from the other meteorites studied here it is more heterogeneous and displays a high abundance of graphitized particles this may be the result of a mixture between 1 the disordered carbon located in the matrix and 2 catalytic graphitized phases associated with metal potentially originating from partial melting events the structural and nanostructural evolution are similar in all ioms this suggests that the structure of the accreted precursors and the parent body conditions of their secondary thermal modifications temperature duration and pressure were similar the limited degree of organization of the most metamorphosed ioms compared with terrestrial rocks submitted to similar temperature suggests that the conditions are not favorable to graphitization processes due to the chemical nature of the precursor or the lack of confinement pressure

a contamination assessment of the ci carbonaceous meteorite orgueil using a dna directed approach the orgueil meteorite has become one of the most well studied carbonaceous meteorites after it fell in france 150 yr ago extraterrestrial organic compounds such as amino acids and nucleobases in the parts per billion ranges were identified in orgueil samples with supporting isotopic analyses however speculations of terrestrial contamination such as organic inclusions in the form of microbes and seeds accompanied the analyses of the orgueil meteorite ever since its fall by using molecular analysis we performed dna extractions and spiking experiments combined with 16s and 18s rrna gene targeted pcr amplification to quantify the level of terrestrial biocontamination our results indicate that terrestrial contamination with dna was insignificant in the investigated meteorite fraction we also remeasured and confirmed concentrations of amino acids found in previous studies and conclude that their rather high concentrations and distribution cannot be explained by terrestrial contamination with microorganisms alone these results represent the first analysis using dna directed tools in the analysis of the orgueil meteorite to determine trace levels of biomarkers

molecular and isotopic indicators of alteration in cr chondrites the cr group of carbonaceous chondrites may represent some of the most primitive extraterrestrial materials available for analysis however in contrast to other chondrite groups the cr organic fraction is poorly characterized the carbonaceous chondrite literature shows that relatively anhydrous thermal processing results in a condensed poorly alkylated o poor macromolecular material while for aqueous processing the converse is true such characteristics can be used to discern the alteration histories of the carbonaceous chondrites we have performed bulk elemental and isotopic analysis and flash pyrolysis on four cr chondrites renazzo al rais elephant moraine eet 87770 and yamato y 790112 to determine the nature of their organic component renazzo al rais and y 790112 release qualitatively similar pyrolysis products although there are some variations al rais macromolecular structure contains substantially higher relative abundances of alkylated and oxidized species and relatively lighter 15n suggesting that it has endured more extensive aqueous processing than the other cr chondrites renazzo appears relatively unprocessed with a low degree of alkylation a lack of detectable nitrogen bearing components and low methylnaphthalene ratio eet 87770 s low abundance of alkylated species suggests its macromolecular structure may be relatively condensed with condensation potentially assisted by a period of mild thermal alteration

speciation of sulfur in the insoluble organic matter from carbonaceous chondrites by xanes spectroscopy sulfur speciation in a comprehensive set of insoluble organic matter iom samples extracted from 3 ci orgueil alais ivuna 5 cm que97990 murchison murray que99355 cold bokkeveld 1 cr renazzo and ungrouped c2 tagish lake chondrites has been studied by k edge xanes micro spectroscopy five main sulfur groups were identified 1 sulfides 2 aliphatic sulfur 3 heterocyclic organic sulfur 4 oxidized organic sulfur and 5 sulfates the iom of the 3 cis and the extensively altered cold bokkeveld cm exhibit a higher abundance of heterocyclic versus aliphatic organic sulfur compared to the other cms and compared to the renazzo and tagish lake chondrites this suggests greater thermal heating on the parent body of cis consistent with the higher temperatures experienced by these chondrites 70 c for the most altered clasts of cold bokkeveld 100 150 c for cis alais may have experienced more heating than ivuna and orgueil the iom of cis contains oxidized organic sulfur suggesting the presence of a mild temperature oxidation process on the parent body among type 2 chondrites other than cold bokkeveld no significant variation of the sulfur speciation was detected this suggests tenuous oxidation processes and a low temperature aqueous alteration 35 c on the parent body the global chemical variations between the cr and cm groups e g h c elemental ratio alkyl groups concentration reported in earlier studies appear to be more the result of chemical variations among the accreted precursors than of post accretional processes

isotopic composition of carbonaceous chondrite kerogen evidence for an interstellar origin of organic matter in meteorites abstract stepwise combustion has revealed systematic patterns of isotopic heterogeneity for c h and n in the insoluble organic fraction m kerogen from the orgueil and murray carbonaceous chondrites those patterns are essentially identical for both meteorites indicating a common source of m kerogen the data cannot be reconciled with a single mass fractionation process acting upon a single precursor composition this indicates either a multi path history of mass dependent processing or a significant nucleogenetic contribution or both if mass fractionation were the dominant process the magnitude of the observed isotopic variability strongly suggests that ion molecule reactions at very low temperatures probably in interstellar clouds were responsible in any case an interstellar rather than solar nebular origin for at least some of the meteoritic organic matter is indicated this has interesting implications for the origin of prebiotic molecules temperatures in the early solar system and the isotopic compositions of volatiles accreted by the terrestrial planets

basement cover relations sevier orogenic belt northern utah precambrian crystalline basement and sedimentary cover rocks were deformed within a regional anticline in the wasatch range of northern utah during the cretaceous to early tertiary sevier orogeny this regional fold had a complex uplift and deformation history and is an imbricated ramp anticline that marks the transition to basement involved deformation large scale thrusting and folding within the basement cored anticline produced about 60 shortening and most of the slip on thrusts within the anticline was transferred into slip on frontal thrusts of the idaho utah wyoming thrust belt a network of ductile deformation zones ddz9s accommodated heterogeneous internal deformation of the basement and cleavage minor folds and vein arrays accommodated internal deformation of the sedimentary cover kinematics of internal deformation are consistent between basement and cover rocks in most areas and vary systematically with structural position recording early layer parallel shortening localized layer parallel shear and minor detachment of the cover and later fanning of structures during large scale folding ddz sets with opposite shear senses accommodated bulk coaxial flattening perpendicular to cleavage away from major thrust faults and ddz9s with consistent shear sense produced simple shear near major thrusts cleavage intensifies and refracts and minor folds tighten in the cover near major thrusts and glide horizons vein arrays record principal extension down the dip of cleavage minor extension parallel to the regional fold axis and differential displacements at high angles to fold axes slip on basement ddz9s produced about 5 to 20 bulk shortening subparallel to the basement cover contact shortening in the cover ranges from about 5 to 30 in most areas but reaches 65 near imbricate thrusts and along glide horizons reflecting heterogeneous simple shear principal extension is down the dip of cleavage and minor extension parallels local fold axes consistent with the geometry of mesoscopic structures