lunar global shape and polar topography derived from kaguya lalt laser altimetry a global lunar topographic map with a spatial resolution of finer than 0 5 degree has been derived using data from the laser altimeter lalt on board the japanese lunar explorer selenological and engineering explorer selene or kaguya in comparison with the previous unified lunar control network ulcn 2005 model the new map reveals unbiased lunar topography for scales finer than a few hundred kilometers spherical harmonic analysis of global topographic data for the moon earth mars and venus suggests that isostatic compensation is the prevailing lithospheric support mechanism at large scales however simple rigid support is suggested to dominate for the moon venus and mars for smaller scales which may indicate a drier lithosphere than on earth especially for the moon and venus

the oligo miocene qom formation iran evidence for an early burdigalian restriction of the tethyan seaway and closure of its iranian gateways in the central iranian esfahan sirjan and qom basins sedimentation of the oligo miocene qom formation took place on extensive mixed carbonate siliciclastic ramps during this time both basins were positioned at the eurasian margin of the tethyan seaway which connected the western and eastern regions of the tethys ocean at least until the late burdigalian during the so called terminal tethyan event the tethyan seaway was then closed due to the collision of the african arabian and iranian eurasian plates facies analysis of the sedimentary record of both basins indicates paleoenvironments ranging from terrestrial to open marine settings including mangrove restricted inner shelf lagoon seagrass meadow reefal and deeper offshore environments recognition of eight depositional sequences and elaboration of an integrated biostratigraphic framework calcareous nannoplankton planktic and larger benthic foraminifers gastropods and pectinids allow us to construct a basin spanning stratigraphy the assignment of the recognized sea level lowstands to the ru 3 to bur 3 lowstands of the global sea level curve enables a comparison with time equivalent sections from the zagros basin which was part of the african arabian plate on the opposing southern margin of the tethyan seaway the so calibrated sections display restrictions of the tethyan seaway and interruption of the south iranian gateways between the qom basin and the proto indopacific in relation to ongoing plate collision during the early burdigalian

magmatic effects of the lunar late heavy bombardment abstract large volumes of mare basalts are present on the surface of the moon located preferentially in large impact basins mechanisms relating impact basins and mare basalt eruptions have previously been suggested lunar impacts removed low density material that may have inhibited eruption and created cracks for fluid flow icarus 139 1999 246 and lunar basins have long been described as catchments for magma e g rev geophys space phys 18 1980 107 and references therein we present a new model for melt creation under near side lunar basins that is triggered by the impacts themselves magma can be produced in two stages first crater excavation depressurizes underlying material such that it may melt in situ second the cratered lithosphere rises isostatically warping isotherms at the lithosphere asthenosphere boundary which may initiate convection in which adiabatic melting can occur the first stage produces by far the largest volume of melt but convective melting can continue for up to 350 ma we propose that giant impacts account for a large portion of the volume and longevity of mare basalt volcanism as well as for several compositional groups including high alumina high titanium kreep rich and picritic magmas

cooperative inversion of magnetotelluric and seismic data on shurab diapirs in central iran using diapirs as liquid or gas storage structures has increased because salt formations are considered to be extremely impermeable and non reactive the process of delineating the diapirs structures ends in lots of challenges due to their geological complexity therefore the integration of different geophysical methods seems to be necessary to cover different physical characteristics of the diapirs shurab diapirs located at the nw of kashan in qom basin of central iran have been considered as candidates for the first natural gas storages in iran a previous 2d seismic survey across the diapir no 4 of shurab could not resolve the diapir structure properly and some ambiguities left unresolved the main goal of this paper is to resolve the structure of diapir no 4 by employing a cooperative inversion of the seismic and magnetotelluric mt data and a comparison with the joint inversion of transverse electric te and transverse magnetic tm modes of the mt data both inversion schemes show the salt and sedimentary sequences of the stratigraphy of the qom basin the sequences of formations from the surface to depth are classified as upper red formation urf qom formation qf and lower red formation lrf the results also show that the salt body has originated from the lrf it is worthwhile to mention that the results from the cooperative inversion provide more details especially on the flanks and overhangs of the diapir no 4 in addition we have come to the conclusion that the right lateral strike slip fault system is the most responsible phenomenon for the development of the diapirs in the survey area and the sen sen fault plays a basic role as an elevator to pushing the salt up the results are in good agreements with the resistivity and density logs of the boreholes moreover the information from the geology the cooperative inversion results on diapir no 4 and the coincidence of the path of the sen sen fault with the outcrops of the diapirs no 1 3 and 4 obviously provide that the tectonic scenario of the existence for diapir no 4 could be appointed to the diapirs no 1 and 3 equally another probable consequence would be the under surface continuation of the salt bodies all along the sen sen fault the verification of which requires regional mt surveys in a regular grid

geologic structure generated by large impact basin formation observed at the south pole aitken basin on the moon the south pole aitken spa basin is the largest clearly recognized basin on the lunar surface determining the composition and structure of the spa basin interior provides critical constraints on the deep crustal and or mantle composition of the moon and improves our understanding of large basin forming impact processes here we present a new mineralogical map of the spa basin interior based on high spatial resolution reflectance spectra using the selene kaguya multiband imager which is combined with topographic data in order to interpret the geologic context the derived mineralogical map suggests extensive distribution of ejected low ca pyroxene dominant mantle material with the presence of purest anorthosite crustal materials surrounding a possible melt pool of 0 26 to 0 33 of the basin diameter near the basin center which is significantly smaller than that suggested by the crater scaling law the absence of clear evidence of lower crustal material is consistent with recent impact simulation results

tertiary of the arabian gulf sedimentology and hydrocarbon potential abstract the paleogene neogene paleogeography of the arabian basin shows a change from the basic continuation of the mesozoic pattern during the paleogene to a new pattern of sedimentation established during the neogene and resulting from movements in the zagros the paleogene shallow water carbonate dominated lithologies in eastern arabia were replaced by deep water neogene carbonates near the zagros and mixed carbonate and clastics in the northern arabian gulf the hydrocarbon potential of these rocks except locally is low and the decreasing amplitude and frequency of faulted and folded structures away from the zagros front suggests that the discovery of fields in structures such as those in iraq iran is low this poverty may however suggest that the untapped potential of the mesozoic rocks may still be high

40ar 39ar dating of quaternary lavas in northwest iran constraints on the landscape evolution and incision rates of the turkish iranian plateau summary we report five new 40 ar 39 ar ages for basaltic lavas in the maku region of northwest iran between ca 1 87 and 0 40 ma which help constrain the tectonic and landscape evolution of this part of the turkish iranian plateau flows originated from the composite volcanoes ararat agridagi tend urekandyigitdagi ineasternturkey anatolia thesevolcanoesarewithin the turkish iranian plateau which is a consequence of the arabia eurasia collision but has a poorly constrained evolution and surface uplift history current plateau elevations are typically 1 5 2 km and relief between non volcanic summits and basins is typically on the scale of 1 km samples are from flows that passed along pre existing river valleys gorges were cut by re established rivers after the eruptions but the great majority of the local relief 95 per cent lies above the sampled flows and so most likely pre dates the volcanism gorge depths and lava ages allow local quaternary fluvial incision rates to be calculated which are 0 01 to 0 05 mm yr 1 these rates imply slow surface uplift of this part of the turkish iranian plateau during the quaternary we therefore constrain the generation of the great majority of relief in the study area to be pre quaternary and caused by the tectonic construction of the plateau rather than a subcrustal origin related to the quaternary magmatism

substrate geology controlling different morphology sedimentology diagenesis and geochemistry of adjacent travertine bodies a case study from the sanandaj sirjan zone western iran abstract a travertine fissure ridge and travertine mound are situated 800 m from each other at the western margin of the active tectono volcanic sanandaj sirjan zone western iran despite their close proximity the two geobodies show a difference in morphology lithofacies lithotypes diagenesis and geochemistry petrographic analysis of the fissure ridge carbonates revealed homogeneous sparitic fabrics with dendritic structures reflecting precipitation under fast flowing conditions from calcite supersaturated spring water the mound carbonates are much more heterogeneous and display dominantly micritic fabrics with mainly volcanic clasts reflecting a lower energy flow regime and lower calcite saturation in contrast to the limited diagenetic overprint of the fissure ridge carbonates the more porous mound carbonates are affected by dissolution cementation and formation of mn fe oxide hydroxides attesting of a strong control on porosity by early diagenetic processes the widespread bright luminescent calcite phases especially in sparitic fabrics within both geobodies display high mn concentrations in calcite indicating suboxic precipitation conditions the overlapping 87sr 86sr signatures and 13c signatures point to a mixture of co2 that dominantly originated from dissolution of the marine carbonate qom formation oligo miocene the different 18o signatures indicate different upwelling systems caused by different substrate settings the fissure ridge formed on a hard and brittle limestone substrate with precipitation from dominantly subsurface sourced fluids the mound travertine formed on top of fairly unconsolidated and fractured volcanic strata the depleted 18o signatures and impure micrite dominated fabrics of the mound travertine reflect precipitation from thermal water that mixed with surrounding groundwater this difference is also reflected in a different calculated precipitation temperature that varies between 4 and 21 c for the mound versus 25 50 c for the fissure ridge our findings show that subsurface geology exerts a major control on precipitation processes resulting in differences in travertine morphology sedimentology diagenesis and geochemistry despite that the travertine bodies occur adjacent to each other

the origin of separate oil and gas accumulations in adjacent anticlines in central iran abstract in central iran two adjacent anticlines contain hydrocarbons within the late oligocene early miocene qom formation the anticlines formed at approximately similar times late miocene pliocene have similar overall geometries but the alborz anticline is an oil field while the sarajeh anticline is a gas field and both are underfilled structures basin modeling and structural restorations identified why the two different accumulations developed the sarajeh and alborz anticlines are modified detachment anticlines asymmetric development of growth strata on the sw margin of the folds was caused by salt withdrawal and normal fault activity on the basin margin which modified the detachment fold style and tilted the basal detachment to the sw the detachment dies out to the ne as the basal lower red formation evaporites pinch out in the same direction yet the alborz anticline is north vergent while the sarajeh anticline is south vergent the mini salt withdrawal basin is best developed on the southern limb of the sarajeh anticline and is responsible for the sw vergence this difference in vergence permitted the alborz anticline to attain 4 way dip closure earlier in its structural history than the sarajeh anticline and consequently the trap was at least partially developed as a four way closure during oil generation and expulsion for the sarajeh anticline oil migrated across the fold when it was still unclosed continued subsidence of the sw fold limb resulted in gas generation and expulsion during the time when the fold attained closure

coral microatolls from the central pacific record late holocene el nino microatolls are discoid corals that have grown laterally because vertical growth is constrained by exposure at lowest tides we demonstrate that a modern reef flat porites microatoll from christmas kiritimati island preserves an oxygen isotope record of substantial sea surface temperature variations related to el nino southern oscillation enso we also show that a late holocene fossil microatoll from the centre of the island contains interannual oxygen isotope variations over an approximate 20 year period three pronounced negative isotope anomalies attributed to warm el nino events are superimposed on an annual cycle el nino events similar to those seen in recent decades appear to have been a feature of mid pacific climate in the late holocene analysis of further microatolls offers a source of pre instrumental el nino tropical climate data it may be possible to extend the nino c proxy to indicate intensity and frequency of enso over the past three millennia

asymmetric thermal evolution of the moon 1 the moon possesses a clear dichotomy in geological processes between the nearside and farside hemispheres the most pronounced expressions of this dichotomy are the strong concentration of radioactive heat sources on the nearside in a region known as the procellarum kreep terrane pkt and the mare basaltic lava flows that erupted in or adjacent to this terrane we model the thermochemical evolution of the moon using a 3 d spherical thermochemical convection code in order to assess the consequences of a layer enriched in heat sources below the pkt on the moon s global evolution we find that in addition to localizing most of the melt production on the nearside such an enriched concentration of heat sources in the pkt crust has an influence down to the core mantle boundary and leaves a present day temperature anomaly within the nearside mantle moderate gravitational and topographic anomalies that are predicted in the pkt but not observed may be masked either by crustal thinning or gravitational anomalies from dense material in the underlying mantle our models also predict crystallization of an inner core for sulfur concentrations less than 6 wt

orbitally paced phosphogenesis in mediterranean shallow marine carbonates during the middle miocene monterey event during the oligo miocene major phases of phosphogenesis occurred in the earth s oceans however most phosphate deposits represent condensed or allochthonous hemipelagic deposits formed by complex physical and chemical enrichment processes limiting their applicability for the study regarding the temporal pacing of miocene phosphogenesis the oligo miocene decontra section located on the maiella platform central apennines italy is a widely continuous carbonate succession deposited in a mostly middle to outer neritic setting of particular interest are the well winnowed grain to packstones of the middle miocene bryozoan limestone where occurrences of authigenic phosphate grains coincide with the prominent carbon isotope excursion of the monterey event this unique setting allows the analysis of orbital forcing on phosphogenesis within a bio chemo and cyclostratigraphically constrained age model la icp ms analyses revealed a significant enrichment of uranium in the studied authigenic phosphates compared to the surrounding carbonates allowing natural gamma radiation gr to be used as a qualitative proxy for autochthonous phosphate content time series analyses indicate a strong 405 kyr eccentricity forcing of gr in the bryozoan limestone these results link maxima in the gr record and thus phosphate content to orbitally paced increases in the burial of organic carbon particularly during the carbon isotope maxima of the monterey event thus phosphogenesis during the middle miocene in the mediterranean was controlled by the 405 kyr eccentricity and its influence on large scale paleoproductivity patterns rare earth element data were used as a tool to reconstruct the formation conditions of the investigated phosphates indicating generally oxic formation conditions which are consistent with microbially mediated phosphogenesis

buildup of a dynamically supported orogenic plateau numerical modeling of the zagros central iran case study the iranian plateau is a vast inland region with a smooth average elevation of c 1 5 km formed at the rear of the zagros orogen as a result of the arabia eurasia collision i e over the last 30 35 myr this collision zone is of particular interest due to its disputed resemblance to the faster himalayan collision which gave birth to the tibetan plateau around 50 myr ago recent studies have suggested that a recent 10 5 ma slab break off event below central iran caused the formation of the iranian plateau here we test several hypotheses through large scale 3082 3 590 km numerical models of continental subduction mod els that incorporate a free upper surface erosion rheological stratification brittle elastic ductile rheologies and metamorphic phase changes density and physical properties and account for the specific crustal and thermal structure of the arabian and iranian continental lithospheres we test the impact of the transition from oceanic to continental subduction and the topographic consequences of the progressive slowdown of the convergence rate during continental subduction our results demonstrate the role of mantle flow beneath the overriding plate initiated as an indirect consequence of slab break off this flow creates a dynamic topography support during continental subduction and results in delamination of the overriding plate lithospheric mantle followed by isostatic readjustment hence of further uplift and maintenance of a plateau like topography without significant crustal thickening the slowdown of the convergence rate dur ing the development of the continental subduction collision phase largely contributes to this process by controlling the timing and depth of slab break off

paleobiogeography of scleractinian reef corals changing patterns during the oligocene miocene climatic transition in the mediterranean abstract during the oligocene miocene greenhouse to icehouse climatic transition the biogeography of reef corals or zooxanthellate like scleractinian corals was gradually changing from a pan tropical tethyan province in the eocene to three reef coral provinces of the western atlantic caribbean indo pacific and mediterranean our reefcoral database encompasses updated and homogenized data on paleoenvironmental and systematics of scleractinian corals occurring in the oligocene and miocene outcrops from circum mediterranean regions provided by most of relatively recently published data in the literature and by the study of published and unpublished collections of coral specimens from the same area including the important collections housed at the mnhn paris and our own collections as there is no validated direct criterion for the identification of the coral zooxanthellate symbiosis in the fossil record and considering the difficulty to use the biogeochemical approaches in the context of this study the subjectivity of the morphological criteria and the relative recent age of the fossil corals we are dealing with a uniformitarian approach has been used for inferring the symbiotic status of scleractinian genera in reefcoral among the 158 genera included in our database 93 can be considered as zooxanthellate and 10 have a doubtful zooxanthellate status this relatively exhaustive database was used to reconstruct the temporal and spatial distribution of scleractinian corals in the mediterranean during the oligocene miocene time in order to discuss the interplaying effects of the global cooling at that time the re organization of the tethyan realm resulting from the african arabian and eurasian plate collision and the emergence of the alpine chains driving the gradual northward movement of the whole region outside the tropical subtropical belt it is shown that the structure of the mediterranean z coral oligocene miocene paleobiodiversity was characterized by many geographically restricted genera with a moderate to short stratigraphical range and a few long ranging widespread genera a major consequence of this structure is that the extinction pattern has proceeded through the preferential extinction of rare occurrence genera through time the potential rapid long distance dispersal of most coral larvae compared to the size of the oligocene miocene mediterranean explains why no biogeographical subprovinces can be distinguished for the z coral fauna on a local scale ecological processes tend to sort coral taxa by limiting z coral development to geographically restricted and discontinuous areas this accounts for the large amount of geographically restricted taxa forming the mediterranean coral fauna the interaction of plate tectonics alpine orogenesis and climate at local to subregional scales exerts strong controls over the spatio temporal distribution of z coral assemblages within the circum mediterranean realm in particular we suggest that the richness and composition of the eastern atlantic coral fauna are indirectly related to the opening and closure of the eastern seaway connection with the indian ocean which controlled the e w circulation of surface waters and hence the westwards dispersal of pelagic larvae at the scale of the whole region the gradual regional climatic change produced by the northwards migration of the entire area superimposed on the global cooling appears in large part responsible for the extinction pattern of z corals through time in the mediterranean biogeographical province

production of subtidal tubular and surficial tempestites by hurricane kate caicos platform british west indies abstract storm infilling of deep open callianassa burrows with molluscan to peloidal packstone was the dominant style of preservable sedimentation produced by the passage of hurricane kate across caicos platform british west indies on 18 november 1985 this moderate hurricane was the first to affect an actively studied portion of the carbonate platform environments of the south florida bahama region in 19 years a time during which many of our concepts of storm sedimentation have evolved prior to hurricane kate much of the shallow platform interior peloidal packstone to grapestone grainstone had a sparse seagrass cover and a highly irregular bottom caused by abundant callianassa mounds hurricane kate flattened the mounded bottom of the platform interior and caused minor smothering and erosion of the seagrass beds a thin surficial tempestite though deposited over much of the platform was difficult to identify because it lacked a coarse base instead much of the reworked surface sediment poured down the large callianassa burrow entrances and filled the vast burrow networks with either a coarse molluscan packstone or peloidal skeletal packstone storm burrow filling tubular tempestites effectively removed the coarse fraction from contributing to a surficial storm layer ten percent of the upper 75 cm of platform interior sediment consists of tubular tempestites from hurricane kate

an example of mixed carbonate pyroclastic sedimentation miocene central basin iran abstract depositional environments of the f member of the qum formation in the central basin of iran have been reconstructed by two approaches 1 a detailed petrographic analysis of microfacies mf 2 an analysis of the vertical superposition of the microfacies using contingency tests both approaches reveal a vertical sequence of eight microfacies designated by letters a h based on petrographic characteristics and environmental significance the studied mf were interpreted in terms of depositional environments as follows mf a basin mf b lower slope mf c reef flank mf d proximal talus mf e organic reef mf f lagoon mf g restricted marine shoal mf h restricted shelf the f member carbonates were deposited in shallow water high energy conditions mostly as reef and fore reef facies carbonate deposition took place on a carbonate ramp under conditions of periodic to almost continuous influx of pyroclastic material the presence of pyroclastic material throughout the studied sections indicates that at the time of deposition an island arc volcanic complex was active nearby the absence of a wide range of typical lagoonal facies indicates that reefal facies developed as a narrow elongated strip close to the shoreline the immediate increase in depth off the reef edge prevented its seaward expansion because the volume of the produced reef talus material was insufficient to provide a shallow foundation for seaward expansion the sedimentary build up of the f member at the studied area evolved from fringing reef to barrier reef through time and space

crustal thickness of the moon implications for farside basin structures 1 based on the latest selene lunar gravity and topography model obtained by kaguya mission we compute the lunar crustal thickness map to investigate differences between farside basin structures the thickest crust is located in the southern rim of the dirichlet jackson basin and the thinnest crust at the moscoviense basin the thickest crust corresponds to the highest topography and is consistent with airy isostasy the thinnest crust is due to an abnormally large mantle plug the crustal thicknesses at apollo 12 14 sites of our crustal thickness model are 45 1 and 49 9 km the crustal thickness map indicates that the differences between recently proposed type i and type ii basins are probably controlled by the ratio between pre impact crustal thickness and impact scale

a quantitative analysis of calcareous nannofossils across a late oligocene paleolatitudinal transect of the north atlantic ocean abstract samples from six ocean drilling sites were analyzed quantitatively across a paleolatitude transect of the north atlantic ocean to determine the paleolatitudinal distribution of calcareous nannofossils in the late oligocene and the effects of that distribution on biostratigraphic resolution quantitative methodology utilized a detrended correspondence analysis dca nannofossil temperature index nti and shannon index h to examine the paleoenvironmental gradients which exerted the most control over the distribution of species and their abundances the dca produced two axes which explain 82 of the data matrix the dca1 explaining 57 of the variance significantly correlates with the nti suggesting that thermal controls were the most important factor in the paleoceanographic distribution of nannofossils the dca2 explained 25 of the variance and significantly correlates with the percent abundance of the taxon reticulofenestra minuta as well as the shannon index suggesting that surface water productivity was an important secondary control the characteristics of the nannofossil assemblage distributions indicate the existence of a well developed latitudinal diversity gradient in the late oligocene of the north atlantic based on the loss of biostratigraphic index taxa in higher paleolatitudes the primary limiter on biostratigraphic resolution for the late oligocene north atlantic is sea surface temperature particularly cold water regimes

arabia eurasia continental collision insights from late tertiary foreland basin evolution in the alborz mountains northern iran a poorly understood lag time of 15 20 m y exists between the initial arabia eurasia continental collision in late eocene to early oligocene time and the acceleration of tectonic and sedimentary processes across the collision zone in the early to late miocene the late eocene to miocene pliocene clastic and shallow marine sedimentary rocks of the kond eyvanekey and semnan basins in the alborz mountains northern iran offer the possibility to track the evolution of this orogen in the framework of collision processes a transition from volcaniclastic submarine deposits to shallow marine evaporites and terrestrial sediments occurred shortly after 36 ma in association with reversals in sediment provenance strata tilting and erosional unroofing these events followed the termination of subduction arc magmatism and marked a changeover from an extensional to a contractional regime in response to initiation of continental collision with the subduction of stretched arabian lithosphere this early stage of collision produced topographic relief associated with shallow foreland basins suggesting that shortening and tectonic loading occurred at low rates starting from the early miocene 17 5 ma flexural subsidence in response to foreland basin initiation occurred fast sediment accumulation rates and erosional unroofing trends point to acceleration of shortening by the early miocene we suggest that the lag time between the initiation of continental collision 36 ma and the acceleration of regional deformation 20 17 5 ma reflects a two stage collision process involving the soft collision of stretched lithosphere at first and hard collision following the arrival of unstretched arabian continental lithosphere in the subduction zone

high resolution chemostratigraphy of a miocene wedge top carbonate shelf san marino fm northern apennines italy the major role of the monterey global fertility event abstract the evolution of the san marino carbonate succession developed on a wedge top basin of the northern apennines during the middle miocene torriana outcrop marecchia valley was studied through a high resolution stable isotope analysis on different carbonate components a marked positive carbon isotopic excursion is identified at ca 16 ma the excellent correlation of the san marino 13c carbonates with the global 13c reference curve from zachos et al 2008 allows to link the marked positive 13c present in the san marino section with the global carbon isotope maximum of the monterey event subordinate long eccentricity driven 13c cycles 405 kyr as recorded by holbourn et al 2007 were also identified the correlation with carbon signatures of coeval successions of the mediterranean region shows that this main carbon isotopic excursion at the burdigalian langhian boundary is widely recorded and predates the crisis of these heterozoan shelves the demise of the san marino shelf resulted from a combination of global and regional factors that controlled the nutrient budget the detrital input and the subsidence of the basin the high resolution chemostratigraphy of san marino succession shows that even though the shelf evolved in the complex setting of a wedge top basin which should be largely influenced by local factors i e tectonic subsidence and detrital input it records the monterey event and its eccentricity paced rhythms with high precision this highlights the strong connection of the monterey event with the development and subsequent demise of shallow water carbonate depositional systems in the mediterranean irrespective of variable and changing local conditions

constraints on palaeodrainage evolution induced by uplift and exhumation on the southern flank of the zagros iranian plateau foreland sedimentary rocks from the northern fars region of iran contain a record of deformation associated with the cenozoic collision between arabia and eurasia that resulted in formation of the zagros orogen the timing of the deformation associated with this event is poorly known to address this we conducted a study of miocene foreland sedimentary rocks 19 7 14 8 ma of the chahar makan syncline using clast composition clay mineralogy and low temperature fission track dating the results showed that most of the sedimentary rocks were sourced from ophiolitic rocks detrital apatite fission track aft age signatures of miocene sedimentary rocks record exhumation in the hanging wall of the main zagros thrust and confirm that the change from underthrusting of the stretched arabian margin to widespread crustal thickening and deformation in the zagros region is no younger than 19 7 ma a transition from late oligocene to mesozoic eocene aft detrital age signatures between 19 7 16 6 ma and 16 6 13 8 ma is interpreted to reflect a possible rearrangement of palaeodrainage distribution that resulted from folding and expansion uplift of the zagros iranian plateau region supplementary material details of the succession of the study area a complete presentation of sample preparation and fission track age measurements of apatite grains and examples of x ray diffractograms are available at http www geolsoc org uk sup18502

the post eocene evolution of the doruneh fault region central iran the intraplate response to the reorganization of the arabia eurasia collision zone

magnetic fields of lunar multi ring impact basins we survey the magnetic fields of lunar multi ring impact basins using data from the electron reflectometer instrument on the lunar prospector spacecraft as for smaller lunar craters the primary signature is a magnetic low that extends to 1 5 2 basin radii suggesting shock demagnetization of relatively soft crustal magnetization a secondary signature as for large terrestrial basins is the presence of central magnetic anomalies which may be due to thermal remanence in impact melt rocks and or shock remanence in the central uplift the radial extent of the anomalies may argue for the former possibility but the latter or a combination of the two are also possible central anomaly fields are absent for the oldest pre nectarian basins increase to a peak in early nectarian basins and decrease to a low level for imbrian basins if basin associated anomalies provide a good indication of ambient magnetic fields when the basins formed this suggests the existence of a magnetic era possibly due to a lunar core dynamo similar to that implied by paleointensity results from returned lunar samples however the central basin anomalies suggest that the fields peaked in early nectarian times and were low in imbrian times while samples provide evidence for high fields in nectarian and early imbrian times

ages and stratigraphy of lunar mare basalts in mare frigoris and other nearside maria based on crater size frequency distribution measurements 1 we report on ages derived from impact crater counts for exposed mare basalt units in the northern part of the lunar nearside hemisphere mare frigoris the eastern and northeastern part of the nearside hemisphere lacus temporis joliot hubble goddard mare marginis and mare smythii the central part of the nearside hemisphere palus putredinis mare vaporum and sinus medii and the southwestern part of the nearside hemisphere grimaldi cruger rocca a lacus aestatis and schickard in mare frigoris we dated 37 basalt units showing ages from 2 61 to 3 77 gyr with most units being formed in the late imbrian period between 3 4 and 3 8 gyr ago in mare vaporum we dated six spectrally homogeneous units that show model ages of 3 10 to 3 61 gyr our model ages of basalts in mare marginis range from 3 38 to 3 88 gyr and are mostly older than basalts in mare smythii 3 14 3 48 gyr the model ages of four units in sinus medii indicate that the basalts in this region formed 3 63 to 3 79 gyr ago we find an excellent agreement of our crater size frequency model ages of the palus putredinis area which contains the apollo 15 landing site with the radiometric ages of apollo 15 samples according to our crater counts basalts in palus putredinis are 3 34 gyr old and this compares favorably with the radiometric ages of 3 30 3 35 gyr of the olivine normative and quartz normative basalts of the apollo 15 landing site lacus aestatis is a small irregular shaped mare patch in the southwestern nearside and shows an imbrian age of 3 50 gyr basalts in lacus temporis in the northeastern nearside formed between 3 62 and 3 74 gyr ago and are therefore older than the basalts in lacus aestatis we found that basalts in craters of the southwestern nearside schickard grimaldi cruger and rocca a are also mostly younger than basalts in craters of the northeastern nearside hubble joliot and goddard while basalt ages vary between 3 16 and 3 75 gyr in the southwest basalts in the northeast are 3 60 3 79 gyr old these results confirm and extend the general distribution of ages of mare basalt volcanism and further underline the predominance of older mare basalt ages in the eastern and southern nearside and in patches of mare peripheral to the larger maria in contrast to the younger basalt ages on the western nearside oceanus procellarum

quantitative measurement method for impact basin characteristics based on localized spherical harmonics abstract characteristics of impact basins are important fundamental knowledge for assessing basin forming impacts and their influence on surficial and interior structural evolutions for lunar and planetary bodies to estimate impact basin characteristics based on spherical harmonic expressions of topographic figures we propose a quantitative method that we apply it to actual lunar topographic data the estimated basin locations center are almost coincident with those determined by visual inspection however the numbers of ring structures differ from previously reported ones the relation between the ring height and the ring diameter coincides well with those reported previously some older basins show discrepancies in the height diameter relation which probably reflect the degree of degradation by subsequent small impacts we recognize a power law relation between the diameters of a ring and a neighboring ring structure that relation suggests that the formation volume and modification of the melt cavity control the formation and size of peak ring and multi ring structures these relations which are thought to reflect the mechanism of the collapse stage of basin formation impact provide helpful constraints for elucidating the long standing problem of how multi ring impact basins are formed

mare volcanism in the lunar farside moscoviense region implication for lateral variation in magma production of the moon 1 accurate estimates of the duration and volume of extrusive volcanism of the moon are essential for understanding the lunar thermal evolution here using new high resolution images obtained by the selene terrain camera we determined the thicknesses and ages of basalts in mare moscoviense one of the most prominent mare deposits on the farside mare volcanism in mare moscoviense was active for at least 1 5 ga following the formation of the moscoviense basin mare basalts are estimated to be at least 600 m thick corresponding to a total volume of 9 500 16 000 km 3 the long duration and large volume of extrusive volcanism are plausibly attributed to the thinner crust of the moscoviense basin relative to those of other farside basins from a comparison with mare volume within a same sized nearside basin we concluded that a magma production in the farside mantle was 3 10 times less than that of the nearside

cenozoic exhumation of the internal zagros first constraints from low temperature thermochronology and implications for the build up of the iranian plateau the iranian plateau is a flat 1 5 2 km high plateau thought to result from the collision between the arabian and eurasian plates since 30 5 ma and may represent a young analogue to the so far better studied tibetan plateau in order to constrain the exhumation history of the internal zagros and of the iranian plateau we herein present apatite u th he ahe and apatite aft and zircon fission track zft data on plutonic rocks from the sanandaj sirjan zone ssz urumieh dokhtar magmatic arc udma central iran and kopet dagh thermochronologic data show that the ssz was exhumed early in the collision process essentially before 25 20 ma with a likely acceleration of cooling during the late eocene from 0 04 to 0 3 mm year results suggest that cooling of the internal zagros migrated from the ssz to the udma during a more mature stage of the continental collision after 17 ma i e coeval with the outward propagation of deformation and topography fronts in the external zagros constant exhumation rates in the udma 0 3 mm year suggest that no significant variation of erosion rates occurred since the onset of continental collision in central iran the overlap of zft aft and ahe ages from gneissic samples points to rapid cooling during the late eocene 42 c myr which is consistent with previous reports on the formation of eocene metamorphic core complexes

benchmark data of a changing sea palaeogeography palaeobiogeography and events in the central paratethys during the miocene abstract the reconstruction and interpretation of terrestrial ecosystems and vegetational patterns in the central european miocene have to take into account the influence of a vast landlocked water body namely the paratethys sea as a northern appendage of the early mediterranean sea it spanned a north south gradient of at least 4 latitude and has been suggested to represent some kind of palaeothermometer which reflected slight expansions or restrictions of climatic belts due to its vulnerable marine connections it was also highly susceptible to major global sea level fluctuations which are reflected in phases of endemism hence a fairly continuous record of marine nearshore assemblages throughout the miocene reflects an extraordinary interplay of sea level fluctuations changes in climate immigrations and blooms in autochthonous elements whilst biostratigraphic implications of these patterns were recognised early in palaeontology a biogeographic model is still lacking the intermingling of palaeogeographic terms with those restricted to biogeography is still commonly used a situation which can be overcome by integrating data from different biota into a new palaeobiogeographic scheme herein a data set of 1809 species level taxa gastropoda and foraminifera serves as the base for interpretations gastropods in particular turned out to be of greatest value for the differentiation of palaeobiogeographic units due to sensitive reactions to all environmental parameters and occupying a wide range of ecological niches based on the excellent gastropod record the proto danubian province early danubian p danubian p balatonian p and a proto caspian subprovince are defined the biogeographic reorganisations are associated with five major biotic events within the gastropod faunas these big five comprise four extinctions the late ottnangian extinction event loee the mid badenian extinction event mbee the badenian sarmatian extinction event bsee the sarmatian pannonian extinction event spee and one exceptional immigration origination event termed the early badenian build up event ebbe foraminifera are less valuable for palaeobiogeographic purposes in the area and time slice studied endemisms are generally lower and turn over rates less dramatic they are however very useful for stratigraphic correlations with the mediterranean and atlantic areas this fairly well calibrated marine biostratigraphy of the central paratethys serves as stratigraphic backbone and control for continental stratigraphy

oroclinal bending in the alborz mountains northern iran new constraints on the age of south caspian subduction and extrusion tectonics abstract in this study we report an extensive paleomagnetic study 76 sites carried out in the alborz mts northern iran with the aim of reconstructing the rotation history and the origin of curvature of this orogenic chain the analyzed deposits are the sedimentary successions of the upper red formation miocene lower red formation oligocene and eocene clastic units paleomagnetic results indicate that the alborz mts can be considered a secondary arc that originated as a linear mountain belt that progressively acquired its present day curvature through opposite vertical axis rotations along its strike the curvature of the arc was entirely acquired after the middle late miocene which is the age of the youngest investigated sediments upper red formation overall our paleomagnetic data indicate that the alborz mts can be considered an orocline our results define for the first time the rotational history of the entire alborz curved mountain belt and enable us to reconstruct the paleogeographic and tectonic evolution of northern iran in the framework of arabia eurasia continental deformation the kinematics inferred by the pattern of paleomagnetic rotations is at odds with the present day kinematics of northern iran characterized by the westward extrusion of the south caspian block and by a left lateral shear between central iran and the central and western sectors of the alborz mts by integrating paleomagnetic data with stratigraphic thermochronological structural and gps information we propose that the initiation of south caspian subduction and the activation of westward extrusion of south caspian block occurred diachronously and that the initiation of the present day kinematics of northern iran was quite recent lower pleistocene

global cenozoic paleobathymetry with a focus on the northern hemisphere oceanic gateways abstract the evolution of the northern hemisphere oceanic gateways has facilitated ocean circulation changes and may have influenced climatic variations in the cenozoic time 66 ma 0 ma however the timing of these oceanic gateway events is poorly constrained and is often neglected in global paleobathymetric reconstructions we have therefore re evaluated the evolution of the northern hemisphere oceanic gateways i e the fram strait greenland scotland ridge the central american seaway and the tethys seaway and embedded their tectonic histories in a new global paleobathymetry and topography model for the cenozoic time our new paleobathymetry model incorporates northeast atlantic paleobathymetric variations due to iceland mantle plume activity updated regional plate kinematics and models for the oceanic lithospheric age sediment thickness and reconstructed oceanic plateaus and microcontinents we also provide a global paleotopography model based on new and previously published regional models in particular the new model documents important bathymetric changes in the northeast atlantic and in the tethys seaway at eocene oligocene transition 34 ma the time of the first glaciations of antarctica believed to be triggered by the opening of the southern ocean gateways i e the drake passage and the tasman gateway and subsequent antarctic circumpolar current initiation our new model can be used to test whether the northern hemisphere gateways could have also played an important role modulating ocean circulation and climate at that time in addition we provide a set of realistic global bathymetric and topographic reconstructions for the cenozoic time at one million year interval for further use in paleo ocean circulation and climate models

cenozoic exhumation history of the alborz mountains iran new constraints from low temperature chronometry the alborz mountains in the north of the turkish iranian plateau mainly developed in the cenozoic as a consequence of the closure of neo tethys and continental collision between arabia and eurasia cenozoic growth of the fold and thrust belt exploited an older palaezoic mesozoic crustal fabric but the extent to which this governed the overall form of the mountain belt is unclear to determine when and how the alborz mountain belt has grown apatite fission track aft and u th he ahe thermochronometry were performed on 46 bedrock samples collected along 8 transects across the range aft central ages range from 157 24 ma to 10 1 ma with most ages falling between 40 ma and 10 ma ahe ages range from 17 2 ma to 6 1 ma the data revealed enhanced exhumation ca 35 5 ma minor exhumation between ca 30 20 ma and an increase in exhumation thereafter this pattern matches the tripartite mid cenozoic stratigraphy of central iran where upper oligocene lower miocene carbonates are sandwiched between terrestrial clastic formations the most intriguing thermochronometric signal found is a major acceleration of exhumation that initiated in the late miocene to early pliocene recorded by the ahe data there does not appear to be a direct tectonic cause for pliocene intensified erosion as convergence rates between arabia and eurasia have remained relatively constant enhanced exhumation at this time may reflect a climatically induced intensification of erosion during caspian isolation and base level fall or a regional tectonic re organization of the arabia eurasia collision or both

chronology of trap formation and migration of hydrocarbons in zagros sector of southwest iran sixty three orogenically controlled oil and gas fields have been discovered in the zagros sector of southwest iran since the turn of the present century most of the fields are giant multi reservoir accumulations producing from fractured carbonate pay zones ranging in age from permo triassic to oligo miocene the most prolific oil producing zones are the asmari formation oligo miocene and the bangestan group upper cretaceous the available geochemical evidence indicates that the major source of the oil is the underlying lower cretaceous albian kazhdumi formation it is argued that in the main oil producing area the kazhdumi source rock was not buried to the depth required for hydrocarbon generation until the eocene and that no significant oil expulsion took place until the miocene entry of oil into the reservoirs is geologically a recent event it postdates the late miocene holocene zagros orogeny that resulted in the formation of the present structural traps it is suggested that the development of growth structures during the late cretaceous and paleogene could have contributed to some hydrocarbon localization prior to the formation of the late tertiary traps

neogene block rotation in central iran evidence from paleomagnetic data paleomagnetic results from oligocene miocene sedimentary units in central iran are used to reconstruct the history of neogene tectonic deformation of this region paleomagnetic data show that in central iran crustal blocks bounded by sets of strike slip faults are rotated to accommodate nne ssw shortening related to arabia eurasia convergence counterclockwise rotations of 20 35 have been measured in the tabas and anarak areas south of the great kavir fault characterized by the presence of n s to nnw sse right lateral strike slip faults conversely in the great kavir and torud areas where ene wsw left lateral strike slip faults have been recognized paleomagnetic results are less conclusive because the small amount of measured clockwise rotation shows a statistically uncertainty which also includes the possibility of no rotation some of these faults have been active during the quaternary up to present day suggesting the possibility that block rotation is still occurring in central iran

lateral heterogeneity of lunar volcanic activity according to volumes of mare basalts in the farside basins estimates for volumes of mare basalts are essential to understand the thermal conditions of the lunar mantle and its lateral heterogeneity in this study we estimated the thicknesses and volumes of mare basalts within five farside basins apollo ingenii poincare freundlich sharonov and mendel rydberg using pre mare craters buried by mare basalts and post mare craters that penetrated non penetrated mare basalts employing topographic and multiband image data obtained by selene kaguya furthermore using the grail crustal thickness model and the mare volumes estimated by this and previous studies we investigated the relationship between the volumes of the mare basalts and the crustal thicknesses the results suggest that the minimum crustal thicknesses within the basins were a dominant factor determining whether magma erupted at the surface and that the critical crustal thicknesses for magma eruption were 10 km on the farside and 20 km on the nearside the total areas of the regions in which magmas could erupt at the surface are 10 times larger on the nearside than on the farside a comparison between the mare volumes within the mare basins on the nearside and the farside shows that magma production in the farside mantle might have been 20 times smaller than that in the nearside mantle implying a stronger dichotomy than previously estimated these results suggest that the mare hemispherical asymmetry should be attributed to both the difference in the crustal thickness distribution and the difference in the quantity of magma production between the nearside and farside mantles

late paleogene terrestrial fauna and paleoenvironments in eastern anatolia new insights from the kagizman tuzluca basin abstract in eastern turkey relatively little work has been undertaken to characterize the sedimentologic and stratigraphical context of the kagizman tuzluca basin until now extending across the turkey armenian border this basin documents the syn and post collisional evolution of eastern anatolia resulting from the closure of the neotethyan seaways and the final collision of the afro arabian and eurasian plates from detailed sedimentological and paleontological studies we propose an interpretation of the lithology and depositional environment of the late paleogene alhan formation located on the western bank of the aras river this sequence of terrestrial clastics rests directly and unconformably onto the ophiolitic melange and it documents several depositional sequences deposited in alluvial plain and lacustrine environments at this stage the age of the alhan formation can only be calibrated by fossil evidence several stratigraphic levels yielding fossil data along the section have been identified but these poor assemblages of fauna and flora hamper extensive comparisons with roughly contemporaneous localities of central and southern asia carnivorous and ruminant mammal remains are reported for the first time from the supposed late oligocene gungormez formation the identified fossil mammal taxa reveal biogeographic affinities between central anatolia and southern asia thus suggesting dispersal between these areas during the oligocene or earlier further studies of the fossil assemblages from the kagizman tuzluca basin and other basins of eastern anatolia and lesser caucasus regions are needed to better constrain the paleobiogeographic models

the shutdown of an anoxic giant magnetostratigraphic dating of the end of the maikop sea abstract paratethys the lost sea of central eurasia was an anoxic giant during oligocene early miocene maikop series times with a size matching the modern day mediterranean sea and a history of anoxic conditions that lasted for over 20 myrs the eastern part of this realm black sea caspian sea domain holds key records for understanding the build up maintenance and collapse of anoxia in marginal seas here we show that the collapse of anoxic maikop conditions was caused by middle miocene paleogeographic changes in the paratethys gateway configuration when a mid langhian badenian tarkhanian transgression flooded and oxygenated the eastern paratethys we present an integrated magneto biostratigraphic framework for the early middle miocene tarkhanian chokrakian karaganian regional stages of the eastern paratethys and date the lithological transition from anoxic black shales of the maikop series to fossiliferous marine marls and limestones of the regional tarkhanian stage for this purpose we selected two long and time equivalent sedimentary successions exposed along the belaya and the pshekha rivers in the maikop type area in ciscaucasia southern russia we show that a significant but short marine incursion took place during the tarkhanian ending the long lasting maikop anoxia of the basin our magnetostratigraphic results reveal coherent polarity patterns which allow a straightforward correlation with the time interval 15 12 ma of the geomagnetic polarity time scale the tarkhanian flooding occurred during a relatively short normal polarity interval that correlates with c5bn resulting in an age of 14 85 ma the regional tarkhanian chokrakian stage boundary is located within c5adn at an age of 14 75 ma and the chokrakian karaganian boundary is tentatively correlated with c5acn and an age of 13 9 13 8 ma our new tarkhanian flooding age reveals a paleogeographic scenario that is different from many previous reconstructions instead of envisaging marine connections to the indian ocean we show that major changes in connectivity between the eastern and central paratethys seas have caused the influx of marine waters during the tarkhanian an increase in marine connectivity with the mediterranean during a short episode of rapid sea level rise triggered mixing and ended the widespread anoxia in the eastern paratethys the mixing episode was short lived 100 kyr as the sea level rise slowed down and connectivity degraded because of tectonic uplift in the gateway area

lunar multiring basins and the cratering process abstract numerous studies of the lunar gravity field have concluded that the lunar moho is substantially uplifted beneath the young multiring basins this uplift is presumably due to the excavation of large quantities of crustal material during the cratering process and subsequent rebound of the impact basin floor using a new dual layered crustal thickness model of the moon the excavation cavities of some nearside multiring basins grimaldi and larger and younger than tranquillitatis were reconstructed by restoring the uplifted moho to its preimpact location the farside south pole aitken spa basin was also considered due to its importance in deciphering lunar evolution restoring the moho to its preimpact position beneath these basins resulted in a roughly parabolic depression from which the depth and diameter of the excavation cavity could be determined using these reconstructed excavation cavities the basin forming process was investigated excavation cavity diameters were generally found to be on the small side of most previous estimates for orientale the modeled excavation cavity lies within the inner rook ring additionally with the exception of the three largest basins serenitatis imbrium and south pole aitken the depth diameter ratios of the excavation cavities were found to be 0 115 0 005 a value consistent with theoretical and experimental results for impact craters orders of magnitude smaller in size the three largest basins however appear to have significantly shallower depths of excavation compared to this trend it is possible that this may reflect a different physical process of crater formation e g nonproportional scaling special impact conditions or postimpact modification processes the crustal thickness model also shows that each basin is surrounded by an annulus of thickened crust we interpret this thickened crust as representing thick basin ejecta deposits and we show that the radial variation in the thickness of these deposits is consistent with scaling laws obtained from small scale experimental studies if multiring basins ever possessed a terraced main crater rim this terraced zone may be presently unrecognizable at the surface due to the emplacement of ejecta deposits that exceed a few kilometers in thickness exterior to the excavation cavity rim we also show that the interiors of many basins were superisostatic before mare volcanism commenced those basins that were closest to approaching a premare isostatic state lie close to or within an anomalous geochemical province rich in heat producing elements

basalt thickness in mare humorum the crater excavation method basalt thicknesses in mare basins have been determined using assumptions about the premare topography of partly buried craters and by comparison to the orientale basin differences in those assumptions have led to a factor of 4 difference in mare thickness estimates further knowledge of thickness is restricted to areas in which buried craters are present using mixing models applied to multispectral images acquired by the clementine spacecraft we have shown that craters in the mare sometimes excavate highland material from below the mare cover using such craters and assumptions about their depth of excavation we obtain independent estimates of basalt thickness our results are in agreement with the lowest of previous thickness estimates we derive a volume of 40 000 km 3 for basalts in mare humorum considerably less than the 110 000 km 3 from previous estimates we also confirm a diameter of 425 km for thc humorum multiring basin based on the clementine gridded global topography assuming an original morphology like orientale

the neotethyan sanandaj sirjan zone of iran as an archetype for passive margin arc transitions the sanandaj sirjan zone of iran is a northwest trending orogenic belt immediately north of the zagros suture which represents the former position of the neotethys ocean the zone contains the most extensive best preserved record of key events in the formation and evolution of the neotethys from its birth in late paleozoic time through its demise during the mid tertiary collision of arabia with eurasia the record includes rifting of continental fragments off of the northern margin of gondwanaland formation of facing passive continental margins initiation of subduction along the northern margin and progressive development of a continental magmatic arc the latter two of these events are critical phases of the wilson cycle that elsewhere in the world are poorly preserved in the geologic record because of superimposed events our new synthesis reaffirms the similarity between this zone and various terranes to the north in central iran late paleozoic rifting preserved as a type granites and accelerated subsidence was followed by a phase of pronounced subsidence and shallow marine sedimentation in permian through triassic time marking the formation and evolution of passive margins on both sides of the suture subduction and arc magmatism began in latest triassic early jurassic time culminating at 170 ma the extinction of arc magmatism in this zone and its shift northeastward to form the subparallel urumieh dokhtar arc occurred diachronously along strike in late cretaceous or paleogene time post cretaceous uplift transformed the zone from a primarily marine borderland into a marine archipelago that persisted until mid tertiary time

middle to late miocene middle eastern climate from stable oxygen and carbon isotope data southern alborz mountains n iran abstract the alborz mountains of northern iran intercept and divert the northern hemisphere westerlies carrying moisture from the mediterranean and black sea and form an orographic barrier to moisture sourced to the north in the caspian sea this implies that terrestrial deposits along the southern alborz mountains leeward side of northerly winds and windward side of westerlies with the respect to tibet and other mountainous terrain in the himalayan karakoram realm potentially track changes in past moisture and erosional regimes and mirror rainfall patterns here we present results of a stable isotope analysis and clay mineral study of the miocene ca 17 5 7 6 ma upper red formation in the foreland of the southern alborz mountains the changes recorded by stable oxygen and carbon isotope data from pedogenic and lacustrine palustrine carbonate in the southern alborz mountains suggest 1 an increase in aridity possibly related to the evolution of the alborz orographic rain shadow which became more efficient between 17 5 and 13 2 ma 2 a steady increase in precipitation between 13 2 and 10 3 ma with a significant increase in rainout along the southern slope of the alborz mountains between 11 and 10 3 ma possibly related to perturbations in atmospheric circulation pattern in the northern hemisphere as suggested by coeval wetter phases in southern europe and 3 a decrease in aridity from ca 9 6 to 7 6 ma possibly reflecting an increase in the seasonality of precipitation based on environmental and climatic changes observed across southern asia and india starting from ca 10 ma we speculate that the topographic evolution of the himalayan tibetan system might have affected the late miocene climate in middle east

siliciclastic and volcaniclastic influences on equatorial carbonates insights from the neogene of indonesia in active tectonic areas of humid equatorial regions nearshore shallow water environments are commonly sites of near continuous siliciclastic influx and or punctuated volcaniclastic input despite significant clastic influence neogene carbonates developed in se asia adjacent to major deltas or volcanic arcs and are comparable with modern mixed carbonate clastic deposits in the region research into delta front patch reefs from borneo and fore arc carbonate platform development from java is described and used to evaluate the effects of siliciclastic and volcaniclastic influx on regional carbonate sedimentation local changes in carbonate producing biota and sequence development regional carbonate development in areas of high siliciclastic or volcaniclastic input was influenced by the presence of antecedent highs changes in the amounts or rates of clastic input delta lobe switching or variations in volcanic activity energy regimes and relative sea level change a variety of carbonate producing organisms including larger benthic foraminifera some corals coralline algae echinoderms and molluscs could tolerate near continuous siliciclastic or volcaniclastic influx approximately equal to their own production rates these organisms adopted various strategies for coping with clastic input including a degree of mobility morphologies adapted to unstable substrate inhabitation or shedding sediment and shapes adapted to low light levels local carbonate production was also affected by energy regime clastic grain sizes and associated nutrient input clastic input influenced the inhabitable depth range for photoautotrophs the zonation of light dependent assemblages and the morphology and sequence development of mixed carbonate clastic successions this study provides data on the dynamic interactions between carbonate and non carbonate clastic sediments and when combined with information from comparable modern environments allows a better understanding of the effects of siliciclastic and volcaniclastic influx on carbonate production

the role of the zagros orogeny in slowing down arabia eurasia convergence since 5 ma 1 large topographic belts along convergent margins have been recognized with the ability to slowdown the kinematics of subduction over geologically short time periods i e few myr because their associated gravitational spreading provides significant resistive force within the framework of plate tectonics the record of past and present day plate kinematics provides important constraints on the dynamics of the lithosphere because plate motion changes must reflect temporal changes in the balance of driving and resisting forces here we focus on the convergence between the arabian and eurasian plates across the zagros mountain belt relative motion across this plate boundary is reconstructed since 13 ma from published paleomagnetic and geodetic data and features a slowdown of 30 from 5 ma to the present day we employ global dynamic models of the mantle lithosphere system to test whether the most recent uplift across the arabia eurasia collision zone including the zagros orogeny may induce the observed slowdown since 5 ma specifically we use constraints from the geologic record to infer past topography and quantify its influence on the convergence rate between arabia and eurasia we test the sensitivity of our models to assumptions made in estimating the paleoelevation by perturbing the orogeny parameterization within reasonable ranges finally we speculate on the potential effects of tethys slab break off changes of the deformation style within the collision zone and the afar plume on the dynamics of convergence our results indicate that orogenic uplift across the arabia eurasia collision zone played a key role in slowing down convergence since 5 ma

building the zagros collisional orogen timing strain distribution and the dynamics of arabia eurasia plate convergence he zagros mountains are the result of the arabia eurasia collision initiated at 35 ma as the rifted arabian lithosphere was underthrusted beneath the iranian plate due to its negative buoyancy the onset of crustal thickening started at 25 ma as recorded by the hinterland exhumation and foreland clastic deposition deformation throughout the arabia eurasia collision zone and the uplift of the iranian plateau occurred after 15 12 ma as a result of shortening thickening of the thin iranian crust we emphasize that only 42 of the post 35 ma convergence is partitioned by shortening within central iran tomographic constraints show ongoing slab steepening or breakoff in the nw zagros whereas underthrusting of the arabian plate is observed beneath central zagros the current subduction dynamics can be explained by the original lateral difference in the buoyancy of the distal margin that promoted slab sinking in nw zagros and underthrusting in central zagros critical wedge approach applied to the zagros favors the hypothesis of strong brittle crust detached above a viscous lower crust in contrast the weak sedimentary cover deforms by buckling of a thick multilayered cover thrust faulting associated with folding occurs in the competent layers and is responsible for most of the earthquakes there is evidence that the role of the slab pull force in driving the arabian plate motion was reduced after 12 ma large scale mantle flow induced by mantle upwelling at the afar plume appears to be the main driver of the arabia plate motion we stress that the main kinematic change in the zagros region occurred at 15 12 ma as the zagros uplifted before the arabian slab detached the zagros appears key to investigate coupling between continental rheology plate driving forces and mountain building in which the role of rift inheritance appears to be central

oligocene and early miocene coral faunas from iran palaeoecology and palaeobiogeography oligocene and early miocene coral assemblages from three sections of central iran are investigated with respect to their palaeoecological and palaeobiogeographic implications these corals are compared with faunas from the mediterranean tethys and the indopacific associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation the studied sections are situated in the foreland basins of the iranian plate which is structured into a fore arc and a back arc basin separated by a volcanic arc the coral assemblages from abadeh indicate a shallowing upward trend infrequently distributed solitary corals at the base of the section indicate a turbid environment above a distinct horizon characterised by a leptoseris stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface small patch reefs with a porites faviidae assemblage are a common feature of late oligocene to early miocene coral occurrences and indicate water depths of less than 20 m the diversity of the coral faunas shows marked differences oligocene corals from the esfahan sirjan fore arc basin comprise more than 45 species of 32 genera and occur in a wide range of environments early miocene corals from the qom back arc basin are less frequent show a lower diversity 13 genera with 15 species and occur in single horizons or small patch reefs

small scale lunar farside volcanism abstract we identified and mapped 28 mare basalt occurrences between the australe and south pole aitken basins on the southern lunar farside and determined their absolute model ages amas by performing crater size frequency distribution csfd measurements our study area can be subdivided into seven major mare basalt occurrences in and around bolyai roche v rosseland pauli and roche craters south of both rosseland and coblentz craters as well as mare patches between eotvos and roche craters the amas of the mare basalts in and around bolyai crater range from 2 1 ga to 3 5 ga two units varying drastically within short distances the mare patches south of coblentz crater contain nine units that have amas ranging from 2 1 ga to 3 8 ga the mare basalts in roche v crater show an ama of 2 2 ga we mapped seven volcanic units in rosseland crater and derived amas for five of these units the mare basalts in rosseland crater show the youngest amas found in our study area ranging from 1 5 ga to 2 9 ga the mare basalt occurrence south of rosseland crater shows significantly older ages with an ama of 3 3 ga the mare basalts in pauli and roche craters show amas from 1 7 ga to 3 1 ga the mare patches between eotvos and roche craters show a similar range of amas from 1 9 ga to 3 1 ga the amas of the mare basalts in our study show that the lunar farside was volcanically active for nearly as long as the lunar nearside 1 2 ga ago or at least longer than previously thought 2 5 ga ago and predicted by models of the ascent and eruption of lunar basalts in addition we calculated thicknesses and volumes of the investigated mare basalts with thicknesses between 21 m and 172 m and volumes from 0 1 km3 to 379 km3 the mare basalts in our study area show a wide range of dimensions similar to other mare basalts of the lunar near and farsides

comparisons of the kinematics and deep structures of the zagros and himalaya and of the iranian and tibetan plateaus and geodynamic implications 1 we compare the geologic histories the deep structures and the present day kinematics of deformation of the himalaya and the adjacent tibetan plateau with those of the zagros and iranian plateau to test geodynamic processes of continental collision shortly after india and arabia collided with eurasia horizontal shortening manifested itself by folding and thrust faulting of sedimentary rock detached from india s and arabia s underlying crystalline basement subsequently slip on thrust faults stacked slices of india s basement to build the himalaya on india s northern margin such faulting has not yet developed in the zagros where collision is more recent and arabia penetrates into eurasia more slowly than india does so that postcollision convergence with eurasia is less the greater elevation thicker crust and more marked heterogeneity of the upper mantle beneath the tibetan than beneath the iranian plateau also reflect a more advanced stage of development moreover while thrust or reverse faulting and crustal shortening continue on the margins of both plateaus normal faulting suggesting horizontal extension and crustal thinning occurs within tibet but not in iran hence the balance of forces that built the high tibetan plateau must have changed apparently some time since 15 ma removal of tibetan mantle lithosphere could have altered that balance if mantle lithosphere beneath the iranian plateau has been removed however the change in force balance has been too small to initiate normal faulting low seismic wave speeds in the uppermost mantle just beneath the moho of both plateaus suggest to us that lithosphere beneath both is thin consistent with late cenozoic removal of it but alternative explanations might account for these low speeds despite its apparently thin and hence presumably weak mantle lithosphere much of central iran undergoes little deformation it illustrates how a crustal block can behave rigidly not necessarily because it is strong but because deviatoric stresses can be small whereas differences between the two regions clearly depend on the amount that arabia and india have penetrated into eurasia which scales with both the dates of collision and rates of convergence we see no differences in the operative processes that depend on the present day rates of convergence

tectonic control on sedimentary facies pattern and sediment accumulation rates in the miocene foreland basin of the southern alborz mountains northern iran 1 the southern alborz mountains of northern iran are an integral part of the arabia eurasia collision zone a magnetostratigraphic and rock magnetic investigation of the eyvanekey stratigraphic section in the southern alborz mountains reveals the spatiotemporal character of sedimentary facies migration in the alborz foreland basin the section constitutes three coarsening upward units units 1 2 and 3 comprising the upper red and hezardarreh formations our data reveal that the upper red formation was deposited between 17 5 and 7 5 ma while the depositional age of the top of the hezardarreh formation can be extrapolated to 6 2 ma slow sediment accumulation rates correlate with sedimentary facies comprising prograding coarsening upward units this is likely the result of intraforeland uplift units 1 and 2 and basin inversion probably associated with a growth syncline located in the proximal foreland unit 3 in contrast fine grained strata at the bottom of each cycle are associated with faster sediment accumulation rates testifying to enhanced flexural basin subsidence in the course of thrust loading progradation of coarse grained facies also occurred during relatively fast sediment accumulation top of unit 2 suggesting that the influx of coarse grained sediment outpaced the storage capacity of the proximal foreland thus despite an overall southward propagation of deformation into the southern alborz foreland the locus of active deformation must have migrated back and forth on a time scale of circa 0 7 to 2 ma

circum mediterranean oligo miocene biogeographic evolution the gastropods point of view based on studies in iran qom basin esfahan sirjan basin zagros mountains in turkey mut and sivas basins in the mesohellenic basin and in northeastern egypt a new palaeobiogeographic concept for the oligocene and miocene in the circum mediterranean area with special emphasis on the distribution patterns of gastropod faunas is presented a very strict biogeographic terminology is proposed to avoid the common fusion of geographic faunistic and geodynamic terms in the palaeontologists jargon our main interest focuses on the affinities and the faunistic interactions between the early mediterranean and the early indo pacific regions during the oligo miocene especially the role of the early indo pacific faunas as the mythic centre of origination of early neogene european mollusc faunas as often vaguely indicated in the literature is critically evaluated this leads to the establishment of a mediterranean iranian province and a western indian eastern african province as palaeobiogeographic subunits of the western tethys region during the oligocene due to major geodynamic and related biogeographic changes in the early miocene the western tethys region no longer existed and was replaced by the proto mediterranean atlantic region for the area of the paratethys the palaeobiogeographic unit danubian province which includes the protocaspian subprovince is proposed furthermore the underrated transatlantic communication of the oligo miocene nearshore mollusc faunas is demonstrated altogether this paper is a contribution to the discussion on the biogeographic concepts classification and nomenclature in palaeontology as initiated by westermann palaeogeogr palaeoclimatol palaeobiogeogr 158 2000 1 13 163 2000 49 68 2002 elsevier science b v all rights reserved

comment on revision of the age of the qom formation in the central iran basin iran by zhu et al journal of asian earth sciences 2007 vol 29 715 721

oligocene miocene basin evolution in se anatolia turkey constraints on the closure of the eastern tethys gateway the oligocene miocene was a time characterized by major climate changes as well as changing plate configurations the middle miocene climate transition 17 to 11 ma may even have been triggered by a plate tectonic event the closure of the eastern tethys gateway the marine connection between the mediterranean and indian ocean to address this idea we focus on the evolution of oligocene and miocene foreland basins in the southernmost part of turkey the most likely candidates to have formed this gateway in addition we take the geodynamic evol ution of the arabian eurasian collision into account the musand elazog u basins located to the north of the bitlis zagros suture zone were most likely connected during the oligocene the deepening of both basins is biostratigraphically dated by us to occur during the rupelian early oligocene deep marine conditions between 350 and 750 m prevailed until the chattian late oligocene when the basins shoaled rapidly to subtidal intertidal environment in tropical to subtropical conditions as indicated by the macro fossil assemblages we conclude that the emergence of this basin during the chattian severely restricted the marine connection between an eastern indian ocean and western mediterranean marine domain if a connection persisted it was likely located south of the bitlis zagros suture zone the kahramanmarasbasin located on the northern arabian promontory south of the bitlis zagros suture zone was a foreland basin during the middle and late miocene possibly linked to the hatay basin to the west and the lice basin to the east our data indicates that this fore land basin experienced shallow marine conditions during the langhian followed by a rapid dee pening during langhian serravallian and prevailing deep marine conditions between 350 and 750 m until the early tortonian we have dated the youngest sediments underneath a subduc tion related thrust at c 11 ma and suggest that this corresponds to the end of underthrusting in the kahramanmarasregion i e the end of subduction of arabia this age coincides in time with the onset of eastern anatolian volcanism uplift of the east anatolian accretionary complex and the onset of the north and east anatolian fault zones accommodating westward escape tec tonics of anatolia after c 11 ma the foreland basin south of the bitlis formed not or no longer a deep marine connection along the northern margin of arabia between the mediterranean sea and the indian ocean we finally conclude that a causal link between gateway closure and global climate change to a cooler mode recorded in the mi3b event d 18 o increase dated at 13 82 ma cannot be supported

volcanism on farside of the moon new evidence from antoniadi in south pole aitken basin abstract the lunar surface is characterized by asymmetric distribution of its volcanic deposits the nearside contains about 90 of the mare basalts while there are a few on the farside with some are in the south pole aitken spa basin which is the largest and oldest impact basin on the moon although the mare volcanism on the nearside of the moon has been very well characterized our understanding of the farside is relatively poor our geological mapping using lunar reconnaissance orbiter lro and chandrayaan 1 moon mineralogy mapper m3 data of 143 km antoniadi impact basin provides new insights into volcanic processes in the southern spa antoniadi has excavated the spa floor as deep as 9 km distribution of secondary craters around antoniadi shows that the basin was formed by oblique impact with the direction of 50 counter clockwise from 178 e longitude our geological mapping has found for the first time several volcanic cones 0 2 2 5 km diameter in association with the mare basalt flows as per morphological classification these are c e n and p type volcanic cones with abundant volcanic fragments in their summit areas the base and summit diameters of these cones are similar to those of marius hills on the nearside of the moon the cumulative size frequency distributions of the summit fragments provide a range of power index values between 3 and 9 suggesting the involvement of dynamic fragmentation of the volcanic materials during the eruptive processes the grabens in the basin floor show evidence for fissure eruption of the mare basalts the graben near the central peak exposes about 140 m thick basalt sequence containing a minimum of five individual lava layers the crater size frequency distributions of the mare deposits suggest an age of 1 6 ga for the flows in the central part of the basin while 2 6 ga for those on the outer floor near the basin wall indicating the episodic volcanism in the basin the young volcanism of 1 6 ga is reported for the first time from spa the m3 data reveal that the basin materials contain abundant low ca pyroxene while the mare basalts with high ca pyroxene we calculated the liquidus density of mare basalts based on feo and tio2 content which suggest a range of density from 2 7 to 2 8 g cm3 which would be lower than a gross lunar crust this would imply the emplacement of basaltic lavas through dikes by simple magma buoyancy or over pressurization of magma chambers if they present at the crust mantle boundary when the magma density is greater than the host crust the 1 6 ga old volcanism in antoniadi suggests that the mantle beneath the spa has been conducive for young magmatism possibly due to presence of kreep like material in the mantle

the middle eocene seeb formation of oman an investigation of acyclicity stratigraphic completeness and accumulation rates in shallow marine carbonate settings abstract the middle eocene seeb formation represents deposition on one of the earliest modern style carbonate platforms i e influenced by seagrasses and mangroves and presents an opportunity to explore controls on the preservation of cenozoic carbonate lithofacies in the study area the seeb fm is dominated by an anomalously thick approximately 250 m and uniform package of shallow marine platform interior sediments these nodular indistinctly bedded shallow subtidal sediments display no evidence for relative sea level change such as subaerial exposure features and lack the shallowing upwards cyclothems that have characterized carbonate sediments deposited in platform interior settings throughout much of the rock record particularly during greenhouse periods we conclude that this is a consequence of thorough bio retexturing of the sediment by burrowing organisms and the roots of marine vegetation which destroyed primary fabrics facies diversity evidence for cyclicity and missing time horizons such as cycle bounding exposure surfaces it seems possible that the remarkable thickness of apparently acyclic seeb fm sediment that built up may reflect increased bio disturbance of the shallow marine environment following the late cretaceous expansion of seagrasses and mangroves a similar lack of peritidal cyclothems may be common to many cenozoic shallow marine carbonate deposits missing time horizons in limestones reflecting erosion or nondeposition have been identified by some authors to explain discrepancies between low calculated accumulation rates of ancient sediments and higher rates measured in comparable modern environments however our studies of the seeb fm suggest that the significance of such missing time horizons in ancient sediments may have been overstated and that apparent differences between modern and ancient accumulation rates are a consequence of the extrapolation of unrepresentative localized high rates of modern sediment production to large platform scale areas our study reinforces the idea that modern sediment production and accumulation rates may be much lower than previously thought because they are typically measured in highly productive areas such as seagrass beds and do not take into account the highly variable nature of carbonate production storage erosion and destruction across platforms therefore far less missing time needs to be inferred for ancient sediments to account for any imbalance between modern and ancient sediment accumulation rates

an oceanic box model of the miocene mediterranean sea with emphasis on the effects of closure of the eastern gateway 1 the early miocene mediterranean sea had two gateways toward the open ocean the indian ocean in the east and the atlantic ocean in the west closure of the eastern connection during the middle miocene had important effects on the water properties and circulation of the mediterranean sea to gain insight into the circulation of the mediterranean sea during the miocene and the effects of closure we apply a box model the model has three boxes representing the atlantic ocean the mediterranean sea and the indian ocean the boxes exchange water heat and salt through surface and deep flow the deep flow is driven by the density contrast between the boxes we analyze the variation of 1 temperature salinity and residence time and 2 magnitude and configuration of the gateway flows in response to changes in the gateways and in atmospheric forcing freshwater and heat fluxes the analysis is presented in three parts preclosure closure and postclosure model results are compared with observations reported in literature the model analysis indicates that 1 prior to closure of the eastern gateway deep flow was most likely west to east in both gateways provided the density of the indian ocean was relatively low 2 the preclosure system was not very sensitive to freshwater and heat flux 3 the response of the mediterranean water properties and flow to gradual closure is nonlinear 4 closure probably resulted in cooling and a rise of salinity and residence time of the mediterranean sea if evaporation exceeded freshwater input and 5 multiple equilibrium states are possible i e different surface and deep flow for the same value of freshwater flux in the case of two gateways in addition we tentatively propose a best fit scenario for the history of closure linking the available data and our model results

hydrogeochemistry stable isotope composition and geothermometry of co2 bearing hydrothermal springs from western iran evidence for their origin evolution and spatio temporal variations abstract this study aims to hydrochemically characterise three co2 bearing springs representing distinct hydrofacies in nw gorveh western iran and interpret them in the light of their geological setting the results of laboratory measurements of elemental concentrations stable oxygen carbon and hydrogen isotopes dissolved and particulate organic and inorganic carbon dic doc poc pic and alkalinity are combined with in situ measurements of ph and temperature parameters such as alkalinity dic ca2 and pco2 concentration display strong positively correlated values with systematic decrease from the spring vent in down flow direction for the three spring systems the inverse correlation of ph and 13cdic is caused by co2 degassing the 18o and d values show no significant variation related to minor or no evaporation due to normal ambient temperatures the low concentration of poc pic and doc compared to that of dic and the lack of correlation between them reflect predominant inorganic carbon in these fluids spring i is oversaturated in calcite with additional dissolution of co2 and despite high concentrations of na and cl undersaturated in halite indicating a fluid of geothermal origin and or reflecting steady state dissolution this is related to water rock interaction processes with carbonate and evaporitic rocks that affected the isotopic signature of 18o which is shifted to the right of the global meteoric water line spring i also represents a partially equilibrated and mature deep chloride type water spring ii and iii are less saline and represent a different fluid circulation and or shorter residence time the two latter springs are characterized by peripheral shallow dilute chloride bicarbonate type waters decreasing key parameters especially in spring iii during the winter suggest that superficial mixing with rain and meteoric water results in high temporal variations cation and stable carbon isotope geothermometry applied to the studied springs reveals an average reservoir temperature of 210 110 and 90 c for spring i and ii and iii respectively the geochemical and isotopic data allowed to depict a conceptual model where the hydrothermal reservoir for spring i is residing in carbonate and evaporitic rocks most likely the qom formation situated at a depth of 3 4 km whereas those of spring ii and iii are likely sourced from a shallower depth 1 2 km in correspondence with carbonate and porous and permeable volcanic rocks integration of hydrofacies with conceptual hydrological and geological models forms the base towards a proper understanding of water circulation patterns increasingly important for sustainable water management and geothermal applications

accommodation of transpressional strain in the arabia eurasia collision zone new constraints from u th he thermochronology in the alborz mountains north iran the alborz range of n iran provides key information on the spatiotemporal evolution and characteristics of the arabia eurasia continental collision zone the southwestern alborz range constitutes a transpressional duplex which accommodates oblique shortening between central iran and the south caspian basin the duplex comprises nw striking frontal ramps that are kinematically linked to inherited e w striking right stepping lateral to obliquely oriented ramps new zircon and apatite u th he data provide a high resolution framework to unravel the evolution of collisional tectonics in this region our data record two pulses of fast cooling associated with sw directed thrusting across the frontal ramps at 18 14 and 9 5 7 5 ma resulting in the tectonic repetition of a fossil zircon partial retention zone and a cooling pattern with a half u shaped geometry uniform cooling ages of 7 6 ma along the southernmost e w striking oblique ramp and across its associated nw striking frontal ramps suggests that the ramp was reactivated as a master throughgoing n dipping thrust we interpret this major change in fault kinematics and deformation style to be related to a change in the shortening direction from ne to n nne the reduction in the obliquity of thrusting may indicate the termination of strike slip faulting and possibly thrusting across the iranian plateau which could have been triggered by an increase in elevation furthermore we suggest that 7 6 m y old s directed thrusting predated inception of the westward motion of the south caspian basin

computer based mollusc stratigraphy a case study from the eggenburgian lower miocene type region ne austria abstract the eggenburg group comprises the type deposits of the lower miocene central paratethys regional stage eggenburgian in ne austria these marine to estuarine deposits transgress in northwestern direction either on palaeozoic rocks of the bohemian massif or on oligocene to lower miocene fluviomarine sediments they are known from three palaeo geographic units situated on the southeastern margin of the bohemian massif these are 1 the southern marginal zone 2 the northwestern n s striking horn basin and 3 the northeastern crystalline plateau termed the eggenburg bay the present study investigates distribution patterns of the exceptionally diverse mollusc fauna composed of 321 taxa species and subspecies within and between those units hierarchical cluster analysis is employed using ward s method and squared euclidean distance calculation a comprehensive database with 1900 sets based on field museum and literature investigations allows compilation of 50 taxonomic lists samples for 30 different localities and six lithostratigraphic units four marine and two brackish formations the resulting grouping pattern implies the existence of four groups three corresponding with palaeo geography and one including low diversity taxon poor samples the analysis of the diversity distribution supports the interpretation that the lower diversity of samples from marine formations stems from secondary distortions such as diagenesis or insufficient sampling hence the samples characterised by a species richness value lower than half of the maximum species richness value of the corresponding formation were excluded from analysis the resulting grouping pattern verified the secondary distortion premise the pattern remained the same except that the low diversity cluster became restricted to samples of brackish origin among the marine samples palaeoecological differences between two fully marine formations from the eggenburg bay were of minor importance as they could not be clearly separated in contrast the individual palaeogeographic regions were shown to be taxonomically coherent but inconsistent with one other as palaeobiogeographic processes were implausible in such a small geographic area the explanation of these differences is based on the time factor including speciation extinction and faunal migration processes the relative stratigraphic position of the horn basin between the marginal zone and the eggenburg bay is implied by hierarchically ordered similarities in order to also indicate their chronological ordinance the index fossil distribution was analysed the chronological pattern is unequivocally provided by the abundant presence of the lower eggenburgian pectinid chlamys gigas schlotheim which is restricted to the marginal zone and the horn basin and by the abundant upper eggenburgian to lower ottnangian pectinids flexopecten palmatus lamarck and chlamys holgeri geinitz which are restricted to the eggenburg bay this refinement of the regional stratigraphic pattern shed light on the eggenburgian marine flooding progression early in the transgression the southern marginal zone was first marine flooded at the same time the horn basin developed an estuarine environment the next phase installed the fully marine environment in the horn basin at the same time the eggenburg bay still a mainland represented a southward pointing cape it first became flooded at the beginning of the upper eggenburgian

application of photogrammetry to the field observation of failed slopes this report analyses the accuracy and applicability of aerial photogrammetry to the study of erosion the study presented in this report uses aerial photogrammetry to study the distribution characteristics of materials from failed slopes in steep mountainous areas where there is frequently slope failure the topography of the area consists of cataclastic and hydrothermally altered soft granite and fresh granite aerial photogrammetry was used to study slopes with active production of materials through erosion locations where eroded materials accumulate and how the eroded materials are washed away by rainfall the use of aerial photogrammetry was effective in gaining an understanding of the movement of eroded earth and sand furthermore the quantitative results obtained through aerial photogrammetry were compared with quantitative results obtained from measurements using observation piles giving very close results since they match the results of existing literature aerial photogrammetry is also thought to be reasonably accurate the results of this research shows that the accuracy of aerial photogrammetry is sufficient for field observations of slopes with fairly active erosion

young mare volcanism in the orientale region contemporary with the procellarum kreep terrane pkt volcanism peak period 2 billion years ago 1 the crater retention ages of the mare deposits within the orientale multi ring impact basin are investigated using 10 m resolution images obtained by the selene kaguya spacecraft in order to constrain the volcanic history of the moon around the nearside farside boundary precise crater counting analyses reveal that mare deposits in the orientale region are much younger than previously estimated 2 9 ga mare basalt in the eastern part of mare orientale and 1 8 2 2 ga mare deposits in lacus veris and lacus autumni maria along the northeastern rings of the basin the latter age estimates indicate that the orientale region experienced volcanic activities 2 billion years after the basin formation impact the dominance of a uniform surface age across the mare deposits in the peripheral regions strongly suggests that these volcanic eruptions are contemporary with the elevated volcanic activity episode proposed for the procellarum kreep terrane on the lunar nearside at 2 ga and that this activity peak is much more widespread than previously estimated the longevity of mare volcanism in the orientale region further suggests high initial temperatures and or high content of heat producing elements in the underlying mantle of this region

timing and characteristics of the latest mare eruption on the moon unraveling the timing and duration of mare volcanism on the moon is essential for understanding its thermal evolution the end of mare volcanism is poorly constrained because mare basalts are incompletely sampled in this study employing selene kaguya high resolution images we performed new crater size frequency measurements for 49 young mare units 3 0 ga in the procellarum kreep terrane pkt in which the latest magma eruption of the moon occurred mare volcanism in this region continued until 1 5 ga suggesting that volcanic activity in this region ceased 1 0 ga after the magma eruption had globally ceased 2 5 3 0 ga volcanic activity may have peaked 1 8 2 2 ga ago the youngest basalts occur around the aristarchus plateau and the kepler crater which are located in the central region of the pkt it is likely that heating in the crust due to the concentration of heat producing elements in the pkt delayed cooling of a partial melting zone in the underlying mantle in contrast with previous basalt dating in this region our results indicate a higher correlation between ages and spectral types of mare basalts the young mare units in the pkt tend to have spectral types corresponding to high titanium contents while low titanium basalts occur mainly in the early stage the titanium variation in mare basalts may reflect vertical heterogeneity in tio2 content in the upper mantle beneath the pkt

foraminiferal biofacies and depositional environments of the burdigalian mixed carbonate and siliciclastic dam formation al lidam area eastern province of saudi arabia abstract four outcrops along a west to east transect in the al lidam escarpment of saudi arabia were investigated to understand the vertical and lateral distribution of foraminiferal assemblages for paleoenvironmental reconstruction the samples were processed using the standard acetic acid method which extracts foraminifera from lithified carbonate rocks without destroying the fossil content the foraminiferal assemblages from the dam formation are dominated by calcareous porcelaneous miliolina quinqueloculina peneroplis triloculina cornuspira sigmoilinita coscinospira spirolina pyrgo borelis followed by hyaline genera elphidium sp ammonia cibicides discorbinella and a minor percentage of agglutinated forms e g textularina the high percentage of calcareous porcelaneous taxa and the absence of planktonic foraminifera indicate that the dam formation was deposited in a restricted carbonate platform environment very shallow hypersaline shallow marine gently sloping ramp inner ramp to mid ramp which ranges from supratidal to subtidal with local reef patches towards the basin the formation was deposited in an arid subtropical climatic environment with water temperatures ranging from 20 to 35 c based on the observed assemblage composition the present day arabian gulf can be considered as a modern analogue for the dam formation during miocene times

impacts do not initiate volcanic eruptions eruptions close to the crater many papers on meteorite impact suggest that large impacts can induce volcanic eruptions through decompression melting of the underlying rocks we perform numerical simulations of the impact of an asteroid with a diameter of 20 km striking at 15 km s 1 into a target with a near surface temperature gradient of 13 k km 1 cold case or 30 k km 1 hot case the impact creates a 250 300 km diameter crater with 10 000 km3 of impact melt however the crater collapses almost flat and the pressure field returns almost to the initial lithostat even an impact this large cannot raise mantle material above the peridotite solidus by decompression statistical considerations also suggest that impacts cannot be the common initiator of large igneous provinces any time in post heavy bombardment earth history