first evidence of high pressure metamorphism in the cover series of the southern menderes massif tectonic and metamorphic implications for the evolution of sw turkey abstract the menderes massif occupies a large part of western turkey it is tectonically overlain by nappes of the izmir ankara suture zone including the bornova flysch zone on its northern flank the afyon zone on its eastern border and the lycian nappes on its southern flank the discovery of magnesiocarpholite kyanite assemblages in the mesozoic cover sequence of the southern menderes massif leads to the very first consideration that a major high pressure hp metamorphic event affected the massif during its alpine evolution estimations of minimum pressure temperature conditions about 10 12 kbar and 440 c suggest a minimum burial of 30 km for the metasedimentary rocks of the menderes massif similar to that for the eocene dilek blueschists which belong to the cycladic complex this finding of high pressure rocks within the menderes cover series as well as the recent description of low grade high pressure parageneses in the basal thrust sheets of the overlying lycian nappe complex has strong implications for the tectono metamorphic evolution of these units the characteristics of this high pressure metamorphism and the deformation features observed in the southern menderes massif allow consideration of a fast burial during alpine subduction and nappe stacking three high pressure units were piled up during the eocene collision of the sakarya continent and the tauride menderes block the lowermost unit consists of the imbricated core and cover of the menderes massif the intermediate unit is the cycladic blueschist complex dilek and samos regions and the uppermost unit is made of the lycian nappes the retrogression of high pressure parageneses from the menderes massif follows an isothermal decompression path and the associated deformation is characterized by a severe stretching oriented n s to ne sw during the high pressure event and its exhumation we propose a tectono metamorphic model in three main stages 1 the southward translation of the high pressure lycian nappes and the burial of the menderes and cycladic metasediments to a depth of at least 30 km to allow their eocene high pressure metamorphism 2 a northward continuum of deformation responsible for top to the north fabrics associated with the main menderes metamorphism peak paleocene eocene and its progressive cooling late eocene north verging folding thrusting imbrication of core and cover series and n s to ne sw intense stretching associated with the menderes high pressure metamorphism and its exhumation these top to the north to top to the northeast movements are probably related to the northward backthrusting of the lycian nappes reactivating the contact between the menderes massif and the lycian nappes as a top to the ne shear zone that allowed exhumation of the lycian high pressure rocks 3 oligo miocene n s extension during which the final exhumation of the metamorphic rocks along kilometre scale low angle detachments occurred

the landing s of philae and inferences about comet surface mechanical properties the philae lander part of the rosetta mission to investigate comet 67p churyumov gerasimenko was delivered to the cometary surface in november 2014 here we report the precise circumstances of the multiple landings of philae including the bouncing trajectory and rebound parameters based on engineering data in conjunction with operational instrument data these data also provide information on the mechanical properties strength and layering of the comet surface the first touchdown site agilkia appears to have a granular soft surface with a compressive strength of 1 kilopascal at least 20 cm thick possibly on top of a more rigid layer the final landing site abydos has a hard surface

stable isotope geochemistry of crude oils and of possible source rocks from new zealand 2 sulfur abstract the sulfur isotopic composition of new zealand low s crude oils and components asphaltenes absorptive filtration fractions and source rock components extracted hydrocarbons kerogen pyrite sulfates were determined oils from the taranaki basin have 34s values from 3 to 14 o the lower values possibly represent plant assimilation of fresh water sulphate higher values particularly those from the west coast basin around 20 suggest closed ocean basin conditions or fast sedimentation rate whereas negative 34s values from east coast basin suggest open ocean or low sedimentation rate conditions it is suggested than an oil source rock relation should show as a similarity in 34s values for total oil and source rock extract kerogen and pyrite shale samples analysed plot outside the corresponding oil range and cannot be considered as possible source rocks however coal samples from the maui 4 well and nelson outcrops show strong isotopic correlations with the taranaki oils

measurements of thermal properties of icy mars regolith analogs in a series of laboratory experiments we measure thermal diffusivity thermal conductivity and heat capacity of icy regolith created by vapor deposition of water below its triple point and in a low pressure atmosphere we find that an ice regolith mixture prepared in this manner which may be common on mars and potentially also present on the moon mercury comets and other bodies has a thermal conductivity that increases approximately linearly with ice content this trend differs substantially from thermal property models based of preferential formation of ice at grain contacts previously applied to both terrestrial and non terrestrial subsurface ice we describe the observed microphysical structure of ice responsible for these thermal properties which displaces interstitial gases traps bubbles exhibits anisotropic growth and bridges non neighboring grains we also consider the applicability of these measurements to subsurface ice on mars and other solar system bodies

tectonic evolution of the gediz graben field evidence for an episodic two stage extension in western turkey western turkey is one of the most spectacular regions of widespread active continental extension in the world the most prominent structures of this region are e w trending grabens e g gediz and buyuk menderes grabens and intervening horsts exposing the menderes massif this paper documents the result of a recent field campaign field geological mapping and structural analysis along the southern margin of the modern gediz graben of pliocene 5 ma age this work provides field evidence that the presently low angle ductile brittle detachment fault is cut and displaced by the high angle graben bounding normal faults with total displacement exceeding 2 0 km the evolution of the n s extension along the gediz graben occurred during two episodes each characterized by a distinct structural styles 1 rapid exhumation of menderes massif in the footwall of low angle normal fault core complex mode during the miocene 2 late stretching of crust producing e w grabens along high angle normal faults rift mode during pliocene quaternary times separated by a short time gap the later phase is characterized by the deposition of now nearly horizontal sediments of pliocene age in the hanging walls of the high angle normal faults and present day graben floor sediments the evolution of extension is at variance with orogenic collapse and or back arc extension followed by the combined effect of tectonic escape and subduction rollback processes along the aegean cyprean subduction zone consequently it is misleading to describe the miocene sediments exhumed on shoulders of the gediz graben as simple graben fill

effects of dispersed particulates on the rheology of water ice at planetary conditions we have investigated the effects of initial grain size and hard particulate impurities on the transient and steady state flow of water ice i at laboratory conditions selected to provide more quantitative constraints on the thermomechanical evolution of the giant icy moons of the outer solar system our samples were molded with particulate volume fractions of 0 001 to 0 56 and particle sizes of 1 to 150 m deformation experiments were conducted at constant shortening rates of 4 4 10 7 to 4 9 10 4 s 1 at pressures of 50 and 100 mpa and temperatures 77 to 223 k for the pure ice samples initial grain sizes were 0 2 0 6 mm 0 75 1 75 mm and 1 25 2 5 mm stress strain curves of pure ice i under these conditions display a strength maximum u at plastic strains e 0 01 after initial yield followed by strain softening and achievement of steady state levels of stress ss at e 0 1 to 0 2 finer starting grain size in pure ice generally raises the level of u petrography indicates that the initial transient flow behavior is associated with the nucleation and growth of recrystallized ice grains and the approach to ss evidently corresponds to the development of a steady state grain texture effects of particulate concentrations 0 1 are slight at these concentrations a small but significant reduction in u with respect to that for pure water ice occurs mixed phase ice with 0 1 is significantly stronger than pure ice the strength of samples with 0 56 approaches that of dry confined sand the magnitude of the strengthening effect is far greater than expected from homogeneous strain rate enhancement in the ice fraction or from pinning of dislocations orowan hardening this result suggests viscous drag occurs in the ice as it flows around the hard particulates mixed phase ice is also tougher than pure ice extending the range of bulk plastic deformation versus faulting to lower temperatures and higher strain rates the high pressure phase ice ii formed in 0 56 mixed phase ice during deformation at high stresses bulk planetary compositions of ice rock 0 4 0 5 are roughly 2 orders of magnitude more viscous than pure ice promoting the likelihood of thermal instability inside giant icy moons and possibly explaining the retention of crater topography on icy planetary surfaces

microstructures of deformed grains in the augen gneisses of southern menderes massif western turkey and their tectonic significance a detailed fabric and microstructural analysis of the granitic mylonites was carried out on the southern side of bes parmak mountain north of selimiye milas the mylonitic augen gneisses have a blastomylonitic texture characterized by large retort shape porphyroclasts or augen of feldspars around which a more ductile medium to fine grained matrix of muscovite biotite quartz and feldspar is deflected feldspars behave in both plastic and brittle fashion because size reduction occurs through grain boundary migration and or subgrain rotation and also through fracturing typical core and mantle structure characterized by a large feldspar core surrounded by a mantle of fine recrystallized grains is very characteristic the majority of plagioclase twins obey the albite twin law however the association with pericline law twinning suggests that many of the twins are mechanical evidence of strain such as deformation twins bent or curved twins undulatory extinction deformation bands and kink bands occur characteristically in plagioclase myrmekite is ubiquitous at k feldspar grain boundaries most notably on the long sides of inequant grains parallel to the s foliation direction which invariably face the maximum finite shortening direction deformation of quartz in mylonitic augen gneisses commonly results in the development of core and mantle structure and type 4 quartz ribbons of elongated preferably oriented newly recrystallized quartz aggregates suggesting a primary dynamic recrystallization undulatory extinction deformation bands and lamellae are the strain related features associated with quartz porphyroclasts micas especially biotite undergo internal deformation by bend gliding and kinking most of the micas are completely attenuated and aligned such that their 001 planes are subparallel or parallel to the margins of quartz ribbons and define the foliation in the rock these microstructures of feldspars quartz and mica in the mylonitic augen gneisses in this part of the southern menderes massif are broadly consistent with fabric development under upper greenschist to lower amphibolite facies conditions rather than almandine amphibolite facies as was previously believed this supports the previous contention of the authors that the protoliths of augen gneisses are younger granitoids and do not represent an exposed precambrian pan african basement in the menderes massif

exhumation with a twist paleomagnetic constraints on the evolution of the menderes metamorphic core complex western turkey 1 much remains to be understood about the links between regional vertical axis rotations continental extension and shortening in western turkey miocene vertical axis rotations have been reported that occur simultaneously with the extensional exhumation of the menderes metamorphic core complex which has been related to back arc extension in the eastern part of the aegean back arc in this paper we explore the spatial and temporal relationships between vertical axis rotations in southwestern turkey and extensional unroofing of the menderes massif to this end we provide a large set of new paleomagnetic data from western turkey and integrate these with the regional structural evolution to test the causes and consequences of oroclinal bending in the aegean region the lycian nappes and bey daglari are shown to rotate 20 between 16 and 5 ma defining the eastern limb of the aegean orocline this occurred contemporaneously with the exhumation of the central menderes massif along extensional detachments and after the latest oligocene to early miocene exhumation of the northern and southern menderes massifs exhumation of the latter two was not associated with vertical axis rotations the lower miocene volcanics in the region from lesbos to usak to the north of the central menderes massif underwent a small clockwise rotation insignificant with respect to eurasia this shows that exhumation of the central menderes massif was associated with a vertical axis rotation difference between the northern and southern menderes massifs of 25 30 this result is in excellent agreement with the angle defined by the trends of buyuk menderes and alasehir detachments as well as the angle defined by the regionally curving stretching lineation pattern across the central menderes massif these structures define a pivot point rotation pole for the west anatolian rotations the rotation of the southern domain including the southern menderes massif the lycian nappes and bey daglari must have led to n s contraction east of this pole the eastern limit of the rotating domain is formed by the transpressional couple of the aksu thrust and kirkkavak fault in the center of the isparta angle previously reported clockwise rotations in the volcanic fields near afyon may be the result of distributed n s shortening east of the pivot point the precise accommodation of this shortening history remains open for investigation late oligocene to early miocene extension in the eastern part of the aegean back arc was ne sw oriented and likely bounded by a discrete transform this transform may be associated with an early evolution of the eastern aegean subduction transform edge propagator fault oroclinal bending in the west anatolian region is likely related to a reconnection of the eastern part of the aegean orocline with the african northward moving plate in tandem with roll back in the aegean back arc comparable to a recently postulated scenario for western greece

recognition and source correlation of migrated hydrocarbons in upper jurassic hareelv formation jameson land east greenland organic geochemical analysis of an interbedded shale sandstone sequence from the upper jurassic hareelv formation jameson land east greenland has revealed oil shows in the sandstones consistent with petroleum generation and migration a comparison of the molecular characteristics of extractable material from the sandstones with those of kerogen and bitumen from the shales indicates that the most likely origin of these shows is generation within the shales with expulsion and short range migration into the sandstones this conclusion is based on comparisons of biological marker distributions stable carbon isotopic compositions of extractable material and kerogen and pyrolysate compositions of kerogen and asphaltenes oil from a seep in the savoia halvo region south of jameson land can be correlated to the jurassic sandstone oil shows based on similar isotopic compositions and asphaltene pyrolysate distributions impregnation of both sandstones and shales throughout the sequence by products generated at higher maturities is considered unlikely but cannot be ruled out by the existing data the molecular characteristics of the sandstone hydrocarbons exhibit a striking similarity to those of oils from the mid norway region the similar geologic ages of the hareelv formation and the kimmeridge clay of northwestern europe which is the acknowledged source of the mid norway oils and the geographic proximity of the two regions at the time of early north atlantic rifting indicate that hydrocarbons from these present day distant regions have been generated from very similar organic facies deposited under similar environmental conditions these results are significant in that in addition to stratigraphic correlation of depositional sequences on both margins of the early rifted north atlantic the hydrocarbons generated from source rocks contained in these sequences now can als be geochemically correlated the results also suggest that jurassic hydrocarbon source facies deposited throughout the early north atlantic are geochemically similar a trait imparted to their generation products

the stable carbon isotopic composition of oil from the taranaki basin of new zealand abstract the average stable carbon isotope ratio of 21 oils from the taranaki basin of new zealand suggests that the source rocks date from the cretaceous period when sedimentation in this basin began stable carbon isotope ratios also confirm the grouping of these oils into the genetic families which were previously suggested by the correlation of source related biomarkers stahl isotope type curves for the oils also reflect the correctness of these relationships a plot of the saturate versus aromatic 13c values for the new zealand oils is particularly valuable for oil correlation in this basin and clearly demonstrates that the ahuroa and stratford oils while separated from the mckee field by some 30 km probably originate from the same oil source formation as do the oils of the mckee field the plot also indicates that the kaimiro mangahewa pukearuhe and waihapa oils are discrete in situ accumulations of petroleum which do not have the characteristics of oils from adjacent fields these conclusions are further supported by the values of the sofer canonical variable for all of the oils additionally the sofer plot provides clear evidence of the predominantly terrigenous origin of the oils in the taranaki basin consideration of the data for these oils leads to a hypothesis that three independent sources of organic material microbes gymnosperms and angiosperms gave rise to the oils in this region

biological marker analysis and stable carbon isotopic composition of oil seeps from tonga abstract petroleum samples collected from shallow holes at two locations on tongatapu tonga have been analysed by computerized gas chromatographic mass spectrometric and stable carbon isotopic techniques the gross composition absence of n alkanes and isoprenoids in the aliphatic hydrocarbon fractions presence of ring a b demethylated hopanes and narrow carbon isotopic composition of the hydrocarbon fractions indicate the samples are moderately to severely biodegraded crude oils the nearly identical terpane distribution and carbon isotopic composition of samples from both locations indicate a common origin the aliphatic hydrocarbon fractions contain a thermodynamically stable assemblage of steranes and triterpanes indicating an advanced stage of thermal maturity for the oil samples these results imply that if the oils have been generated within sediments on the tonga platform the source beds are probably in the more deeply buried and thermally mature western section of the platform

aegean tectonics strain localisation slab tearing and trench retreat abstract we review the geodynamic evolution of the aegean anatolia region and discuss strain localisation there over geological times from late eocene to present crustal deformation in the aegean backarc has localised progressively during slab retreat extension started with the formation of the rhodope metamorphic core complex eocene and migrated to the cyclades and the northern menderes massif oligocene and miocene accommodated by crustal scale detachments and a first series of core complexes mccs extension then localised in western turkey the corinth rift and the external hellenic arc after messinian times while the north anatolian fault penetrated the aegean sea through time the direction and style of extension have not changed significantly except in terms of localisation the contributions of progressive slab retreat and tearing basal drag extrusion tectonics and tectonic inheritance are discussed and we favour a model 1 where slab retreat is the main driving engine 2 successive slab tearing episodes are the main causes of this stepwise strain localisation and 3 the inherited heterogeneity of the crust is a major factor for localising detachments the continental crust has an inherited strong heterogeneity and crustal scale contacts such as major thrust planes act as weak zones or as zones of contrast of resistance and viscosity that can localise later deformation the dynamics of slabs at depth and the asthenospheric flow due to slab retreat also have influence strain localisation in the upper plate successive slab ruptures from the middle miocene to the late miocene have isolated a narrow strip of lithosphere still attached to the african lithosphere below crete the formation of the north anatolian fault is partly a consequence of this evolution the extrusion of anatolia and the aegean extension are partly driven from below asthenospheric flow and from above extrusion of a lid of rigid crust

granitoid rocks of the southern menderes massif southwestern turkey field evidence for tertiary magmatism in an extensional shear zone recent field campaign in the southern menderes massif in southwestern turkey revealed that the so called core of the massif comprises two distinct types of granitoid rocks an orthogneiss traditionally known as augen gneisses and leucocratic metagranite where the latter is intrusive into the former and the structurally overlying cover schists these differ from one another in intensity of deformation degree of metamorphism and kinematics the orthogneiss display penetrative top to the n nne fabrics formed under upper amphibolite facies conditions during the eocene main menderes metamorphism mmm whereas foliation and stretching lineation exists in the leucocratic metagranites but are not strongly developed the leucocratic metagranites show evidence of syn to post emplacement deformation in a series of weakly developed top to the s ssw fabrics formed under lower greenschist facies conditions leucocratic metagranite bodies occur all along the augen gneiss schist contact in the southern menderes massif they are emplaced as sheet like bodies into country rocks previously deformed and metamorphosed during a top to the n nne alpine orogeny along a ductile extensional shear zone located between orthogneisses and metasediments which was possibly active during emplacement the data presently available indicate that emplacement and associated ductile extensional deformation occurred during late oligocene early miocene time these results confirm previous contentions that there are tertiary granites in this part of the menderes massif

extensional v contractional origin for the southern menderes shear zone sw turkey tectonic and metamorphic implications the southern menderes massif in southwest turkey consists mainly of orthogneisses and overlying palaeozoic middle paleocene schists and marbles the contact between the two distinct rock types is almost everywhere structural herein named the southern menderes shear zone a s facing high angle ductile shear zone that separates metamorphic rocks of differing grade although there is a consensus that the shear zone was associated with top to the s ssw shearing and is of tertiary age its origin and nature have been highly debated over the last decade some claim the contact is a thrust fault while others have argued for an extensional shear zone integration of field and microstructural data the identification of different fabrics associated kinematics and overprinting relationships with fission track thermochronology and the p t paths of the rocks above and below the shear zone supports the conclusion that the southern menderes shear zone is an extensional shear zone and not a thrust the data are consistent with a model that the exhumation and cooling of the southern menderes massif occurred after a period of extensional deformation pervasive top to the n nne high temperature medium pressure ductile shear structures d 2 deformation overprint an early hp event d 1 deformation the subsequent top to the s ssw greenschist shear band foliation d 3 deformation developed mostly around the orthogniess schist contact and forms the most characteristic features of the massif the top to the n nne structures are attributed to the main alpine constructional deformation that developed during back thrusting of the lycian nappes during the latest palaeogene collision between the sakarya continent and the anatolide tauride platform across the neotethyan ocean the top to the s ssw structures are interpreted to be the result of the exhumation of the massif during the activity of the southern menderes shear zone the presence of these two distinct fabrics with differing kinematics suggests that the southern menderes shear zone operated as a top to the n nne thrust fault during early alpine contractional deformation but was later reactivated with an opposite sense of movement top to the s ssw during subsequent oligocene miocene extensional collapse

paleoreconstruction by biological markers abstract during diagenesis and conversion of the original lipid fraction of biological systems to petroleum hydrocarbons the following four basic events needed for paleoreconstruction can be monitored by biological markets 1 sourcing 2 maturation 3 migration and 4 biodegradation actual cases of applying biological markers to petroleum exploration problems in different parts of the world are demonstrated cretaceous and phosphoria sourced oils in the wyoming thrust belt can clearly be distinguished from one another by high quality source fingerprinting of biomarker terpanes using gas chromatography mass spectrometry identification of recently discovered biological markers head to head isoprenoids allows subtle source differentiation between oils from sumatra the degree of crude oil maturation in basins from california alaska russia wyoming and louisiana can be assessed by specific novel biomarker ratios 20s 20r sterane epimers field evidence from such interpretation is confirmed by laboratory pyrolysis of the rock an example of immature sumatra rock is given extensive migration is documented by biomarkers in several oils the effect of biodegradation on biomarker steranes and terpanes is exemlified in a california basin all biological marker results are consistent with the geological setting and add a new dimension in assisting the petroleum explorationist toward paleo reconstruction

discussion on the evolution of the southern menderes massif in sw turkey as revealed by zircon dating journal vol 156 1999 1021 1030 scientific editing by randy parrish erdin bozkurt graham park write loos reischmann 1999 employ geochronological evidence single zircon ages from the augen gneisses of the southern menderes massif sw turkey to conclude that the granitic precursors were intruded between c 521 and 572 ma averaging 550 ma during the late precambrian and early cambrian they claim that this evidence contradicts the views of bozkurt et al 1993 1995 and bozkurt park 1994 who provided the first field evidence for the intrusive nature and tertiary age of the granitic protolith of the gneisses in a complex polydeformed environment like the menderes massif reliance on geochronological evidence alone can be seriously misleading and any viable geological model must satisfy both geochronological and field constraints we would point out that similar old zircon ages are widely known from the literature reischmann et al 1991 loos reischmann 1995 hetzel reischmann 1996 dannat reischmann 1998 hetzel et al 1998 koralay et al 1998 and that it was emphasized in our papers bozkurt et al 1993 1995 bozkurt park 1994 1997 a b that these ages apparently contradict the intrusive contact relations between the metagranites and the structurally overlying metasedimentary envelope loos reischmann confirm the presence of an intrusive contact close to lake bafa but question the intrusive contact relations in the selimiye milas area described by us they claim that the interference of various deformation phases led to the formation of tectonic lenses of the augen gneisses within the schists and vice versa and suggest that it is these structures that we bozkurt et al 1993 1995 interpreted as intrusive contacts however we would emphasise that the intrusive contacts described in

the bishop tuff new insights from eruptive stratigraphy the 0 76 ma bishop tuff from long valley caldera in eastern california consists of a widespread fall deposit and voluminous partly welded ignimbrite the fall deposit f exposed over an easterly sector below and adjacent to the ignimbrite is divided into nine units f1 f9 with no significant time breaks except possibly between f8 and f9 maximum clast sizes are compared with other deposits where accumulation rates are known or inferred to estimate an accumulation time for f1 f8 as ca 90 hrs the ignimbrite ig is divided into chronologically and or geographically distinct packages of material earlier packages ig1 were emplaced mostly eastward are wholly intraplinian coeval with fall units f2 f8 lack phenocrystic pyroxenes and contain few or no glass mountain derived rhyolite lithic fragments earlier packages ig2 were erupted mostly to the north and east are at least partly intraplinian interbedded with fall unit f9 to the east contain pyroxenes and have lithic fractions rich in g

organic geochemistry of sediments in new zealand part i a biomarker study of the petroleum seepage at the geothermal region of waiotapu abstract the saturated hydrocarbons from the oil seepage at waiotapu in new zealand were examined by gc and gcms techniques of molecular fingerprinting the petroleum was characterised by a high ratio of phytane nc18 2 37 and low ratios of pr ph 0 64 and saturates aromatics 0 60 this study revealed that the oil was derived from terrigenous organic matter and it had neither migrated from its source nor suffered biodegradation the source rocks were deposited under anoxic conditions and these rocks lay within pleistocene sediments which were immature with respect to oil generation the location of the source rocks within a geothermal field had accelerated the generation of petroleum since the source rocks would have been too young and shallow to generate petroleum in the absence of geothermal energy

tectonic transport directions of the lycian nappes in southwest turkey constrained by kinematic indicators abstract the orientation asymmetry and cross cutting relationships of the structures along the contact zone between the lycian nappes and the menderes massif suggest the presence of three deformation phases in the milas region of southwest turkey the first deformation phase d1 is characterized by a ductile deformation with top to the ne sense of shear structural data of the first deformation measured along the uppermost part of the menderes massif and the base of the lycian nappes suggest that the lowermost unit of the lycian nappes was emplaced initially from southwest to northeast onto the menderes massif during the early eocene the second deformation phase d2 is also ductile in nature and is characterized by an e w trending stretching lineation with a bivergent sense of shear which is probably related to the load of the overlying nappes a third deformation phase d3 is characterized by south dipping normal faults with top to the s sense of movement this third deformation phase can be related to southward movement of the lycian nappes along a low angle decollement zone the tectonic contact between the menderes massif and the lycian nappes and their strongly deformed rocks are unconformably covered by approximately flat lying coal bearing early middle miocene sedimentary rocks which constrains the upper time limit for all three deformation phases

3d analysis of an ordovician igneous ensemble a complex magmatic structure hidden in a polydeformed allochthonous variscan unit the basal units of the allochthonous complexes of nw iberia represent a fragment of the external edge of gondwana subducted and subsequently exhumed during the variscan collision the structural analysis carried out in orthogneissic massifs of the southern part of one of these the malpica tui unit reveals the generation of recumbent folds and associated axial planar foliation during their exhumation these folds nucleated in irregular igneous bodies that were initially deformed during the subduction event and show east to southeast vergence down plunge projection of surface data and a series of regularly spaced cross sections have been used to build 3d models of the two main bodies of orthogneiss of calc alkaline and peralkaline compositions respectively the first is presently a lens shaped body folded in a recumbent syncline whereas the peralkaline gneiss also affected by a train of asymmetric recumbent folds in the south exhibits in the north a fold like structure which is interpreted as inherited from its primary geometry that of a ring dike pluton

comet 9p tempel 1 evolution of the surface abstract comet 9p tempel 1 was imaged during two consecutive perihelion passages according to thomas et al thomas et al 2013 icarus 222 453 466 one scarp located at 40 s receded up to 50 m i attempted to use this observation to constrain local material properties of the nucleus for this purpose i simulated recession of a model scarp due to sub dust sublimation of ice i have found that the observed recession of the scarp can be reproduced when the dust mantle has high porosity about 0 8 and low thermal conductivity about 10 mw m 1 k 1 as found for artificial dust layers krause m blum j skorov yu v trieloff m 2011 icarus 214 286 296 taking into account the temperature dependence of the sublimation coefficient of ice reduces the calculated recession rate of the scarp by about 40

the strength of ice saturated extraterrestrial rock analogs abstract in situ resource utilization isru activities have been identified by the national research council as one of the most important scientific endeavors of the coming decade the failure of the mupus pen experiment on rosetta s philae lander to penetrate the surface of comet 67p demands knowledge of the mechanical properties of extraterrestrial materials in such environments to such an end we conducted laboratory strength measurements at cryogenic conditions of two terrestrial rocks bishop tuff and indiana limestone as potential cometary and asteroid analogs respectively we measured failure strength of dried and fully saturated samples under constant displacement rate compressional loading at temperatures of 77 k 295 k and for most confining pressure of 5 mpa the strength of saturated samples increased dramatically with decreasing temperature below the ice point saturated limestone from 30 mpa at 295 k to 200 mpa at 150 k and below and saturated tuff from 26 mpa at 240 k to 160 mpa at 150 k some ductility or distributed fracturing was evident in both saturated rock types above 150 k the saturated tuff was stronger than pure ice at all conditions but its transition from brittle to ductile deformation with temperature closely paralleled that of ice the results of this study will be useful to future sample retrieval missions or isru maneuvers the fully saturated state of our samples and use of bishop tuff as an unconsolidated cometary analog likely means our results are upper estimates for substrates we may encounter in our solar system pending corroboration and refinement of these preliminary measurements the large increase in compressive strength we observed in the saturated materials at cryogenic temperatures suggests that future missions must prepare technology with the energetic and mechanical capability to penetrate very hard substrates

paleomagnetism of the miocene soma basin and its structural implications on the central sector of a crustal scale transfer zone in western anatolia turkey abstract the izmir balikesir transfer zone ibtz is a crustal scale major tectonic feature in western anatolia accommodating differential extension between the menderes mcc and cycladic ccc core complexes the kinematics and evolution of the southern part of the ibtz are well constrained but its northern continuation remains unstudied this part is crucial in understanding the complete evolution of western anatolian tectonics as well as a possible link between the ibtz and north anatolian fault zone nafz in this study new and extensive paleomagnetic structural and stratigraphic data were collected from the soma basin these results show that the basin evolved as a part of the ibtz including two separate rotational phases during the first middle miocene phase deformation was characterized by transcurrent tectonics and associated block rotations as much as 50 clockwise during which the ibtz evolved as a wide dextral shear zone during the second late miocene recent phase the mode of deformation in the aegean region switched from localized to distributed extension related to the acceleration of the tearing off of the african oceanic slab below the aegean region this led to the narrowing of the ibtz as a discrete brittle shear around the soma basin manifested by decoupling of dextral strike slip and normal faulting in this period the soma basin underwent around 21 counter clockwise rotation based on our new results the ibtz extends further to the north and possibly interacts with the southern branch of the nafz since the late miocene

supra pan african unconformity between core and cover series of the menderes massif turkey and its geological implications abstract well preserved primary contact relationships between a late proterozoic metasedimentary and the metagranitic core and palaeozoic cover series of the menderes massif have been recognized in the eastern part of the cine submassif on a regional scale metaconglomerates occur as laterally discontinuous channel fill bodies close the base of the metaquartzarenite directly above the basement the pebbles in the metaconglomerates consist mainly of different types of tourmaline rich leucocratic granitoids tourmalinite and schist in a sandy matrix petrographic features geochemical compositions and zircon radiometric ages 549 6 3 7 552 3 3 1 ma of the diagnostic clasts of the metaconglomerates e g leucocratic granitoids and tourmalinites show excellent agreement with their in situ equivalents 549 0 5 4 ma occurring in the pan african basement as stocks and veins the correlation between clasts in the metaconglomerates and granitoids of the basement suggests that the primary contact between the basement and cover series is a regional unconformity supra pan african unconformity representing deep erosion of the pan african basement followed by the deposition of the cover series hence the usage of core cover terminology in the menderes massif is valid consequently these new data preclude the views that the granitic precursors of the leucocratic orthogneisses are tertiary intrusions

tectonic significance of synextensional ductile shear zones within the early miocene alacamdag granites northwestern turkey synextensional granitoids may have significant structural features leading to the understanding of the evolution of extended orogenic belts one of the highly extended regions the aegean region includes a number of metamorphic core complexes and synextensional granitoids that developed following the alpine collisional events the alacamdag area in northwestern turkey is one of the key areas where miocene granites crop out along the boundary of various tectonic units structural data from the early miocene alacamdag granites demonstrated two different deformation patterns that may provide insights into the development of granitic intrusions and metamorphic core complexes 1 steeply dipping ductile shear zones caused emplacement of syn tectonic granite stocks they include kinematic indicators of a sinistral top to the sw displacement this zone has also juxtaposed the izmir ankara zone and the menderes massif in the west and east respectively 2 gently dipping ductile shear zones have developed within the granitic stocks that intruded the schists of the menderes massif on the structurally lower parts kinematic data from the foliated granites indicate a top to the ne displacement which can be correlated with the direction of the hanging wall movement documented from the simav and kazdag metamorphic core complexes the gently dipping shear zones indicate the presence of a detachment fault between the menderes massif and the structurally overlying izmir ankara zone mesoscopic to map scale folds in the shallow dipping shear zones of the alacamdag area were interpreted to have been caused by coupling between ne sw stretching and the accompanying nw se shortening of ductilely deformed crust during early miocene times one of the ne trending shear zones fed by granitic magmas was interpreted to form the northeastern part of a sinistral wrench corridor which caused differential stretching between the cycladic and the menderes massifs this crustal scale wrench corridor the izmir balikesir transfer zone may have controlled the asymmetrical and symmetrical extensions in the orogenic domains the combination of the retreat of the aegean subduction zone and the lateral slab segmentation leading to the sinistral oblique slip tearing within the eurasian upper plate appears to be a plausible mechanism for the development of such extensive ne trending shear zones in the aegean region

the occurence of unusual c27 and c29 sterane predominances in two types of oman crude oil abstract two types of oman crude oils reveal unusual sterane distributions type a which is the more common 74 examples is characterised by a predominance of c 29 iso and normal steranes and generally none or only very low relative concentrations of rearranged steranes the triterpanes are characterised by the predominance of the c 29 17 h 21 h norhopane over the c 30 17 h 21 h hopane and non predominant c 20 c 30 tricyclic terpanes the c 29 steranes of this type of crude were not derived from the c 29 sterols of land plant origin frequently proposed as the source of c 29 steranes since there is good geological evidence that these crudes were generated from a pre cambrian source rock a geological period when land plants did not exist the type b crude oil 11 known examples is characterised by a strong predominance of c 27 iso normal and rearranged steranes relatively lower concentrations of 17 h 21 h hopanes and relatively high concentrations of c 20 c 30 tricyclic terpanes the remarkably different biomarker characteristics of these crude oils imply that the organisms active in the depositional environment of the respective source rocks were significantly different

biological marker distribution and significance in oils and rocks of the monterey formation california abstract the biological marker distributions of several oils core extracts and solid bitumens of the monterey formation of california have been studied sterane terpane and monoaromatic steroid hydrocarbons were analyzed in samples from the san joaquin los angeles ventura and santa maria basins the sterane patterns of both oils and extracts are characterized by 1 a low relative concentrations of diasteranes 2 b low 20s 20r 5 14 17 ethylcholestane ratios 3 c relatively high concentrations of cholestane vs methyl and ethylcholestane isomers san joaquin basin samples contain significant amounts of the 5 isomer which is generally absent in samples from other basins the carbon number distribution of 5 14 17 20r steranes is similar for all oils regardless of api gravity depth or basin location and is suggestive of open marine depositional conditions for the source material involved 17 h l8 h 21 h 28 30 bisnorhopane is present in almost all samples certain san joaquin basin oils and extracts contain 1 a a series of 25 nor hopanes including 25 28 30 trisnorhopane 2 b a distinctive monoaromatic steroid hydrocarbon distribution 3 c an aliphatic hydrocarbon fraction devoid of n paraffins biological marker characteristics suggest that the monterey oils examined originated early in the maturational sequence from elastics poor source material api gravities of the monterey formation oils examined vary monotonically with 1 a bisnorhopane hopane ratios 2 b aromatized regular sterane ratios and 3 c the concentration of monoaromatized steranes relative to terpanes and regular steranes these oil gravity correlations exist regardless of sample depth or basin location

geochemical signature variation of pre syn and post shearing intrusives within the najd fault system of western saudi arabia abstract late precambrian intrusive rocks in the arabian nubian shield emplaced within and around the najd fault system of saudi arabia feature a great compositional diversity and a variety of degrees of deformation i e pre shearing deformed sheared mylonitized and post shearing undeformed that allows placing them into a relative time order it is shown here that the degree of deformation is related to compositional variations where early usually pre shearing deformed rocks are of dioritic tonalitic to granodioritic and later mainly post shearing undeformed rocks are mostly of granitic composition correlation of the geochemical signature and time of emplacement is interpreted in terms of changes in the source region of the produced melts due to the change of the stress regime during the tectonic evolution of the arabian nubian shield the magma of the pre shearing rocks has tholeiitic and calc alkaline affinity indicating island arc or continental arc affinity in contrast the syn and post shearing rocks are mainly potassium rich peraluminous granites which are typically associated with post orogenic uplift and collapse this variation in geochemical signature is interpreted to reflect the change of the tectonic regime from a compressional volcanic arc nature to extensional within plate setting of the arabian nubian shield within the context of published geochronological data this change is likely to have occurred around 605 580 ma