late miocene stepwise aridification in the asian interior and the interplay between tectonics and climate abstract the mid latitudinal central asian continent is characterized by large sand deserts and gobi stony desert in this context it is of interest to study the timing and forcing mechanisms of aridification in the region here we present multiple geochemical climatic proxies from late cenozoic strata in the tarim basin of northwestern china a region sensitive to climatic change the results yield long term climatic records covering a time interval of 13 3 to 2 5 ma we find that a general trend towards a dry climate was superimposed by two stepwise aridification events the first lesser aridity phase occurred at 7 5 3 ma and the second extreme aridity episode was initiated at 5 3 ma based on the correlation between climatic change and regional tectonic events we propose a mechanism to explain the climatic variations the general long term drying trend since the mid miocene was a response to global climatic cooling while the stepwise aridification since the latest miocene was controlled mainly by regional tectonic uplift

the topography and morphology of low shields and associated landforms of plains volcanism in the tharsis region of mars abstract the morphology and topography of volcanic landforms provide critical information to the investigation of their tectonic setting and the physical characteristics e g rheology of their eruption products their investigation is also an important prerequisite for studies of comparative planetology e g the comparison between surface features of the earth and other planetary bodies numerous small and low shield volcanoes on mars and associated vents and lava flows have previously been compared to terrestrial plains style volcanism which is defined as being an intermediate style between flood basalts and the hawai ian shields this study investigates the topography and morphology of martian landforms associated with plains volcanism using mola moc themis hrsc and hirise data low shields and other landforms of plains volcanism on mars display similarities with terrestrial basaltic volcanic fields and we do not observe any features that do not have morphologic analogues on earth the most typical landforms of martian plains style volcanism are low shields defined as volcanic shields with diameters of typically less than 50 km heights of a few hundred meters only and extremely shallow flank slopes of less than 0 5 other surface features related to plains style volcanism on mars are craters fissure vents cinder and spatter cones lava flows that are commonly associated with lava channels and tubes lava inflation features and volcanic rift zones our results reconfirm the viking orbiter based conclusion that plains volcanism in the eastern snake river plains is perhaps the best terrestrial morphological analogue for these martian surface features icelandic shields distinct structures in hawai i and other basaltic landforms also show similarities to martian plains volcanism sinuous rilles previously not described in association with plains volcanism on mars are interpreted as evidence for high eruption rates the extremely shallow flank slopes of the low shields suggest the eruption of shield building lavas with low viscosity which might be the result of high eruption temperatures high effusion rates a low si and a high mg content along with a possible high fe content or a combination of these factors the spatial distribution of low shield clusters in tharsis does not show any obvious association with large scale tectonic features plains volcanism might represent a relatively recent type of volcanism on mars which is not related to mantle plumes but to a zone of partial melting in an anomalously warm mantle underneath a thickened crust schumacher and breuer geophys res lett 34 l14202 doi 10 1029 2007gl030083 2007

messinian evaporite deposition during sea level rise in the gulf of lions western mediterranean the messinian salinity crisis resulted from desiccation of the mediterranean sea after its isolation from the atlantic ocean at the end of the miocene stratal geometry tied to borehole data in the gulf of lions show that the pre crisis continental shelf has been eroded during a major sea level fall and that sediments from this erosion have been deposited in the basin this detrital package is onlapped by high amplitude seismic reflectors overlain by the messinian salt and the upper evaporites towards the shelf the transition between regressive deposits and overlying onlapping sediments is characterised by a wave ravinement surface suggesting that a significant part of the onlapping reflectors and overlying messinian evaporites were deposited during a relatively slow landward migration of the shoreline the clear boundary between the smooth wave ravinement surface and the subaerial messinian erosional surface observed on the gulf of lions shelf and onshore in the rhone valley is interpreted to have resulted from a rapid acceleration of the mediterranean sea level rise at the end of the messinian salinity crisis numerical simulation of this cycle of sea level change during the messinian salinity crisis and of precipitation of thick evaporites during the slow sea level rise shows that this scenario can be modelled assuming a value of evaporation minus precipitation of 1 75 m3 m2 yr in the deep mediterranean basins

very recent and wide spread basaltic volcanism on mars new spacecraft data provide increasing evidence for a dynamic environment on presenta day mars exogenic processes such as impact cratering mass wasting processes and active dune migration have all been observed to modify the surface no traces of current endogenic activity have been found yet but some studies point to very localized volcanism in the last few millions of years however no systematic study of young volcanic surfaces had been performed so far we present absolute model age determinations of plains volcanism on mars as derived from impact crater sizefrequency distributions extended areas in tharsis the largest volcanoa tectonic region on mars have been resurfaced by lava flows in the last few tens of millions of years we also present results on the rheologic properties of these lava flows inferred from morphometric measurements yield strengths are in the range of 100a 300 pa and viscosities reach values of 10 2 to 10 3 pa s indicating basaltic compositions the results imply that mars retained until recently and probably still retains enough internal heat to produce widea spread plaina style volcanism producing lowa viscosity lava flows throughout large parts of tharsis

high heat flux on ancient mars evidence from rift flank uplift at coracis fossae 1 we have identified flexural uplift at the flanks of the coracis fossae rift valley modeling the topography the elastic thickness is constrained to 10 3 12 5 km the corresponding mechanical thickness and thermal gradient are 15 19 km and 27 33 k km 1 respectively the time of rifting is dated by evaluating the crater size frequency distribution of key surface units related to the rifting thus the heat flux between 3 5 and 3 9 ga is calculated to be 54 66 mw m 2 furthermore the stresses supported by the rift bounding faults are estimated to be below 5 mpa we speculate that this weakness may be connected to the presence of water below the surface

thermal convection in a volumetrically heated infinite prandtl number fluid with strongly temperature dependent viscosity implications for planetary thermal evolution parameterized models of the thermal evolution of planets are usually based on the assumption that the lithosphere convecting mantle boundary can be defined by an isotherm at a temperature below which viscosity is infinite on geologic timescales recent experimental results argue against this assumption we have investigated both the definition of the lithosphere convecting mantle boundary and the power law relation describing convecting heat transfer based on numerical experiments of thermal convection in a volumetrically heated fluid with temperature dependent viscosity other recent studies have treated only the heating from below but volumetric heating is likely to be the dominant mode of heating in planetary mantles either as a consequence of radioactive heating or as a proxy for secular cooling convection can occur either in the whole box or be located under a stagnant lid in the lid regime convection is driven by a temperature contrast depending on the rheology of the fluid and the interior temperature this result in agreement with experimental studies indicates that boundary between the stagnant lid and the convecting layer similar to the lithosphere convecting mantle boundary cannot be defined as a fixed isotherm during thermal evolution of planets the viscosity contrast in the convecting mantle remains constant not the temperature at the bottom of the lithosphere we present an example showing that the evolution of planets is strongly dependent on the criterion chosen to define the lithosphere convecting mantle boundary for reasonable values of the activation energy for thermally activated creep the temperature defining the lithosphere convecting mantle boundary the mantle temperature and the thickness of the lithosphere could be larger than expected from previous models which treat the base of the lithosphere as a fixed isotherm

the messinian problem in the pannonian basin eastern hungary insights from stratigraphic simulations abstract earlier studies revealed a prominent unconformity in the messinian stratigraphic record of the lacustrine pannonian basin but it was unclear what factors were responsible for the formation of this unconformity and thus its origin remained controversial the problem was further complicated by the fact that stratal patterns in the messinian varied significantly along the paleo margins of the lake our study introduces quantitative stratigraphic simulations to analyze the role of subsidence sediment supply and lake level changes in the formation of the unconformity and the various architectural patterns that evolved in response to the messinian events the results suggest that a relative lake level fall occurred in the messinian accompanied and followed by tectonic inversion in several parts of the basin since the rate of tectonic subsidence and or uplift varied in space and time the size of the relative lake level fall varied significantly across the basin while various stratal architectural patterns formed in the same time interval the age of the unconformity was estimated based on seismic correlations with paleomagnetic chronozones to be between 5 6 ma which was refined by stratigraphic simulations galeacysta etrusca cysts were found in the unconformity which confirmed its late messinian age the surface is called the intra messinian unconformity imu in this paper seismic interpretations and simulations of stratal architecture led to the formulation of a basin fill model and identification of four stratigraphic architectural patterns related to messinian events including a major lake level fall and coeval and subsequent uplift events in certain parts of the basin

mechanical modeling of thrust faults in the thaumasia region mars and implications for the noachian heat flux abstract insight into the state of the early martian lithosphere is gained by modeling the topography above surface breaking thrust faults in the southern thaumasia region crater counts of key surface units associated with the faulting indicate a scarp emplacement in the late noachian early hesperian periods between 4 0 and 3 7 gyr the seismogenic layer thickness at the time of faulting is constrained to 27 35 km and 21 28 km for the two scarps investigated implying paleo geothermal gradients of 12 18 and 15 23 k km 1 corresponding to heat flows of 24 36 and 30 46 mw m 2 the heat flow values obtained in this study are considerably lower than those derived from rift flank uplift at the close by coracis fossae for a similar time period indicating that surface heat flow is a strong function of regional setting if viewed as representative for magmatically active and inactive regions the thermal gradients at rifts and scarps span the range of admissible global mean values this implies d t d z 17 32 k km 1 with the true value probably being closer to the lower bound

messinian crisis what happened around the northeastern aegean abstract the effects of the severing of the atlantic mediterranean connection during the 400 000 year messinian event are also observed around the northern aegean during this time a sea of brackish water character developed between paratethys in the north and the mediterranean in the south this sea is named here egemar this basin was principally fed by surrounding rivers and by paratethyan waters that entered egemar via a connection through the sea of marmara which was then a bay of the paratethys the sedimentary sequence deposited in egemar is principally composed of limestones containing brackish water fauna paratethyan however there are some intercalations containing mediterranean species five intercalations of mediterranean character are found within the sedimentary sequence of egemar indicating the re establishment of an atlantic mediterranean connection from time to time and thus replenishment of marine waters the turolian is represented by continental clastics which interdigitate with the brackish water cycles implying a number of regressions egemar eventually became part of the eastern mediterranean due to a major transgression during the early pliocene

late miocene to early pliocene climate variability off nw africa odp site 659 abstract a high resolution 18 o record obtained on benthic foraminifera cibicides wuellerstorfi combined with clay mineralogy major element concentrations and sr nd isotopes have been investigated for the odp site 659 located off north africa in order to reconstruct african monsoon intensity between 6 2 and 4 9 myr mineralogical and geochemical results indicate that sedimentation on the cape verde plateau results from a mixture of sediments deriving from the neighbouring saharan arid region and the wet african equatorial zone sahelian band characterised by a low and a high state of weathering respectively past variations in terrigenous inputs from these areas allow us to track past extension and displacement of the west african monsoon itcz system maximal summer insolation induced a northward migration of the inter tropical convergence zone itcz wetter conditions in the sahel and a diminishing of wind erosion over the south sahara and sahel in addition there was an increase in river input to the cape verde plateau of sediments derived from southern sedimentary sources which are characterised by high kaolinite contents and cia values and low k al and ti al ratios on the other hand minimal summer insolation induced a southward movement of the itcz drier climate in the sahel and stronger easterly winds resulting in an increase in dust transport from the sahara to the cape verde plateau dust particles are characterised by high illite and smectite content and by a low chemical state of weathering low cia values and high k al and ti al ratios finally our results provide new clues regarding the re flooding of the mediterranean sea at the end of the msc 5 33 myr this event was associated with enhanced aridity in the sahara implying a reorganisation of the atmospheric circulation and a southward migration of the itcz

a seismic model of the lunar mantle and constraints on temperature and mineralogy abstract we determine seismic profiles of the moon s interior using travel times obtained from a re analysis of the apollo data due to the limited number of quakes and stations travel times errors were determined and used in the inversions our model has a mean crustal thickness of about 30 km in the region of the apollo network with a 10 km zone of brecciation below the crust mean values of seismic velocities in the upper mantle are rather well constrained and are in the range 7 6 7 8 and 4 35 4 45 km s 1 for p and s waves respectively velocity variations in the middle mantle are less well defined in the zone of deep moonquakes below 740 km depth velocities increase slightly to 8 15 0 23 and 4 5 0 10 km s 1 for p and s waves respectively we analyse the seismic profile in term of mineralogy and temperature constraints our preferred models are a pyroxenite model for the upper mantle and a magnesian rich model for the lower mantle with increasing mg with depth we find temperatures of about 1100 k elastic lithosphere limit and 1500 k thermal lithosphere limit for radii of about 1400 and 1000 km respectively and show that the lunar mantle is probably depleted in th and u by at least 70 compared to an earth reference value of 25 7 ppb u for a crustal thickness of 40 km with a mean 1010 ppb th concentration we then find bulk th and u abundances comparable to and possibly lower than currently accepted terrestrial values

climate modelling sensitivity experiments for the messinian salinity crisis abstract the repeated isolation of the atlantic ocean during the messinian led to at least the partial desiccation of the mediterranean sea and to the deposition of massive evaporites messinian salinity crisis overall proxy data do not indicate dramatic climatic changes in the mediterranean region for the time of the messinian salinity crisis but a constant climate seems to be unrealistic at first sight to analyse the climate response to environmental changes in the mediterranean region during the messinian salinity crisis we perform climate modelling sensitivity experiments as a reference base we use a tortonian simulation tort and simulate three messinian sensitivity scenarios 1 the mediterranean sea surface 1500 m lower than the normal sea level msc lowsea 2 the mediterranean basin completely desiccated the resulting land surface 1500 m lower and covered by grassland vegetation msc lowgrass and 3 the mediterranean sea simply replaced by grassland vegetation msc grass all sensitivity experiments represent extreme scenarios for analysis of general patterns of messinian climate change in msc lowsea mean annual temperatures in the mediterranean basin increase by 2 c and surrounding regions get cooler by up to 3 c as compared to tort the lowering of the mediterranean sea level increases the annual precipitation in the south western part of europe and in north western africa up to 1000 mm a in msc lowgrass as compared to tort the mediterranean basin strongly heats up by 7 c while temperatures in the surrounding areas do not change more than 2 c the precipitation in the mediterranean basin significantly decreases up to 600 mm a precipitation in the areas surrounding the mediterranean basin does not change substantially in msc lowgrass but rainfall in w africa increases up to 600 mm a in msc grass as compared to tort temperatures in the mediterranean region increase by 4 c this is twice as high as the temperature increase which resulted from lowering the mediterranean sea surface in msc lowsea annual rainfall over the mediterranean basin in msc grass is 400 mm a lower than the rainfall in tort proxy based climate reconstructions for the time of the messinian salinity crisis indicate no dramatic climatic changes around the mediterranean in contrast to this for eastern n africa and eastern europe climate changes are indicated the msc lowsea and msc lowgrass sensitivity experiments show that the strong environmental changes in the mediterranean realm during the msc did not necessarily cause strong climatic changes at the margins of the mediterranean basin therefore the present modelling studies are in agreement with climate proxy data from the mediterranean region additionally our results principally agree with the climate changes inferred from the fossil record of central and eastern europe for eastern n africa our modelling studies contradict proxy data based on our results weak climatic changes indicated by the fossil record at the mediterranean coastlines are realistic

an important current reversal influx in the rifian corridor morocco at the tortonian messinian boundary the end of tethys ocean atlantic psychrospheric and temperate mesopelagic faunas found in the lower messinian marls in morocco indicate that a strong eastward flowing bottom current was present in the rifian corridor before the salinity crisis this influx began just before diatomite deposition in the paleo mediterranean continued during a decrease in species diversity in coral reef formation and diminished with the initial stages of brine concentration in the deep water phase of the crisis the influx is most readily studied in a condensed section of marl in the bou regreg valley near rabat the beginning of this siphon event coincides with the tortonian messinian boundary 6 4 ma subchron 6n1 it is identified by 1 a change in the planktonic foraminifera from dominance of warm tropical epipelagic globorotalia menardii with globigerinoides to the temperate mesopelagic gl miotumida plexus with conomiozea 2 the sudden appearance of an upper psychrospheric ostracode fauna with agrenocythere pliocenica and oblitacythereis ruggierii 3 a change in nannoflora and 4 beginning of the 6 3 ma global carbon shift the initial strong influx stage of the siphon lasted at least 0 7 m y decreasing after the middle of chron 5 ca 5 7 to be lost ca 5 3 ma conditions for the siphon formed when the continental climate created a deficit in the water budget of the paleo mediterranean sea the reversal took place when tectonic movement in the foredeeps of the betic rif orogene changed the thresholds of the twin straits the rifian corridor and the iberian portal inflow increased rapidly in the southern corridor to draw in waters from beneath the rising atlantic pycnocline while paleo mediterranean overflow water pmow continued out of the northern iberian portal the invasion of nappes or olistoliths first into the portal and then into the corridor led to the end of the outflow of the pmow terminating the need for the siphon and then to the isolation of the paleo mediterranean

correlation of late miocene to early pliocene sequences between the mediterranean and north atlantic ocean drilling program odp site 982 in the north atlantic contains a complete latest miocene to early pliocene section that was tuned to the astronomical timescale by correlating the record of gamma ray attenuation gra bulk density to summer insolation at 65 n and the benthic 18o signal to orbital obliquity for the interval from 4 6 to 7 5 ma the astronomical tuning of the site 982 record permits a direct bed to bed correlation to the cyclostratigraphy of messinian sections in the mediterranean krijgsman et al 1999a 2001 the benthic 18o signal at site 982 records a latest miocene glacial period that lasted from 6 26 to 5 50 ma and consisted of 18 glacial to interglacial oscillations that were controlled by the 41 kyr cycle of obliquity although the intensification of glaciation at 6 26 ma may have contributed to the restriction of the mediterranean it preceded the depositional onset of the lower evaporite unit at 5 96 ma by some 300 kyr the transition from stage tg12 to tg11 at 5 5 ma marks the end of the latest miocene glacial period and precedes the miocene pliocene boundary by 170 kyr although benthic 18o values are relatively low and 18o of bulk carbonate reaches a minimum at the miocene pliocene boundary at 5 33 ma there is no single event that would indicate deglaciation and sea level rise as the cause of the reflooding of the mediterranean we conclude that glacioeustatic changes alone were not responsible for either the start or end of evaporite deposition during the messinian suggesting that tectonic or local climate changes in the mediterranean region were the dominant cause s

evaporite accumulation during the messinian salinity crisis the suez rift case 1 the mediterranean basin may have not always been connected to the atlantic ocean during the messinian salinity crisis 5 96 5 33 myr the mediterranean sea reduced progressively its connection with the global ocean by a complex combination of tectonic and glacio eustatic processes during this period deep erosion occurred on the margin and on the continent furthermore a large quantity of evaporites was deposited in the basins 1500 m the way by which the evaporites accumulated in the various sub basins has not been precisely determined here we demonstrate by quantitative analysis that a combination of several mediterranean sea level drawdown events associated with limited atlantic sea inflow and continuous river discharge can explain the quantity of evaporites in the mediterranean basins and the observation of an intermediate lowstand at 500 m using a paleogeographical reconstruction and a numerical model we show that the evaporites of the gulf of suez gos are a consequence of the threshold which disconnected the gos red sea from the eastern mediterranean at the end of the miocene

convection in a variable viscosity fluid newtonian versus power law rheology abstract a number of finite element calculations of convection in a variable viscosity fluid have been carried out to investigate the effects of non newtonian flow when rheology is also subject to a strong temperature and pressure influence a variety of cases has been studied in the range of effective rayleigh numbers between 104 and 106 including different modes of heating and a range of values for activation energy and activation volume power law creep with a stress exponent of 3 turns out to lead to considerably different flow pattern and heat transfer properties than newtonian rheology in general the effect is to reduce viscosity contrasts imposed by p t dependence which can lead in some circumstances to the mobilisation of otherwise stagnant regions within the cell the properties of non newtonian flow can be closely imitated by a newtonian fluid with a reduced value of the activation enthalpy bh with b 0 3 0 5 it appears possible that non newtonian rheology plays a key role in determining the convective style in a planetary mantle

ancient volcanism and its implication for thermal evolution of mars abstract volcanism plays an important role in the formation and thermal evolution of the crusts of all terrestrial planets martian volcanoes have been extensively studied and it has been suggested that the volcanism on mars that created the visible volcanic features was initiated in the noachian 3 8 ga and continued to the late amazonian 4 0 ga volcanoes are preserved in the heavily cratered southern highlands most of these are central volcanoes with diameters ranging from 50 to 100 km and heights of 2 3 km most of them are spatially adjacent to and temporally continuous with the tharsis and circum hellas volcanic provinces suggesting that these two volcanic provinces have experienced more extensive and longer duration volcanism than previously thought these edifices are heavily cut by radial channels suggesting that an early phase of aqueous erosion occurred and ended prior to the emplacement of the encircling hesperian lava fields

coupled core mantle thermal evolution of early mars 1 several arguments point out that at the end of planetary accretion the core of mars was likely to be much hotter than its mantle resulting in the formation of a completely or partially molten thermal boundary layer at the base of the mantle here we address the following questions how did the superheated core cool and what role did it play in the early mantle dynamics of mars we divide the coupled core mantle evolution of early mars into two stages during the first stage vigorous convection within the molten boundary layer removes the heat from the core so that the boundary layer expands up as the boundary layer gets thicker the temperature of the layer decreases eventually the temperature of the molten boundary layer drops down to the temperature for the rheological transition melt fraction 40 within 100 years this stage is described by a parameterized convection approach the second stage is modeled in spherical shell geometry using the fully three dimensional finite element code citcoms a single plume superplume forms by the instability of the thermal boundary layer the superplume stage lasts much longer on the scale of millions to hundreds of millions of years depending on the mantle viscosity during both stages of evolution the heat flux can easily satisfy the requirements for the dynamo

magnetostratigraphic biostratigraphic and stable isotope stratigraphy of an upper miocene drill core from the sale briqueterie northwestern morocco a high resolution chronology for the messinian stage we report a high resolution stable isotope carbonate magnetostratigraphic and biostratigraphic record from a 175 m drill core from the sale briqueterie which is part of the bou regreg section in northwestern morocco the sale drill core spans the interval from paleomagnetic chron c4n partim to c3r earliest gilbert which represents the time leading up to and including the isolation and desiccation of the mediterranean i e the messinian salinity crisis during chrons c3an and c3ar 6 935 to 5 894 ma the isotope and carbonate signals display quasi periodic variations with estimated periods of 40 and 100 kyr respectively we interpret the 40 kyr 18o variations as reflecting changes in global ice volume caused by obliquity induced changes 41 kyr in solar insolation in polar regions the 100 kyr carbonate variations probably represent long term modulation of the amplitude of the precessional cycle 21 kyr which is not resolved by our sampling frequency the cyclic nature of the oxygen isotope signal permits us to extend the isotope nomenclature of shackleton et al 1994a from stage tg24 in chron c3r earliest gilbert to stage c3ar 18o 18 at the base of chron c3ar 6 935 ma a major change in paleoceanographic conditions is recorded across the tortonian messinian boundary which we correlate to chron c3bn at 7 04 ma benthic foraminiferal 18o values increased by an average of 0 4 in two steps at 7 17 ma and 6 8 ma and 13c values decreased by 0 7 0 8 between 7 1 and 6 8 ma representing the late miocene carbon shift the first step in 18o values coincides with an inferred reversal in deep water circulation through the rifian corridor and the second correlates with the base of the tripoli formation and onset of crisis conditions in the mediterranean we suggest that the increase in 18o values represents at least in part an increase in global ice volume that lowered sea level and contributed to the establishment of a negative water budget in the mediterranean average 18o values remained high throughout most of chrons c3ar and c3an reaching maximum 18o values during isotope stages tg20 and 22 in chron c3r earliest gilbert the glacio eustatic falls associated with these events may have resulted in the complete isolation of the mediterranean from the world ocean shackleton et al 1994a following stage tg12 in the sale record there exists a trend toward progressively lower 18o values that may represent a series of marine transgressions that eventually reflooded the mediterranean and ended the salinity crisis

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

constraints on the maximum crustal density from gravity topography modeling applications to the southern highlands of mars abstract gravimetric methods commonly used to constrain crustal parameters such as the mean crustal thickness and density are ambiguous with a noted trade off between these parameters however combining two different methods the geoid topography ratio and bouguer inversion in regions that are homogeneous with respect to lateral density variations and compensation state can help to constrain a maximum density of the crust for the martian noachian southern highlands a combination of these methods gives us a maximum crustal density of 3020 70 kg m 3 assuming a single layer crustal structure we also test various two layer crustal structures to check how they influence the results we find a possibility to fit the observed data with a crust having a dense uniformly thick lower crust but in these models the upper crustal density was also limited to 3000 kg m 3 the obtained results together with the findings on crustal densities and composition of other regions on mars are consistent with various scenarios of crustal evolution a temporal increase in the crustal density or a large scale density variation that has been already manifested in the early evolution during the formation of the crustal dichotomy

vegetation sea level and climate changes during the messinian salinity crisis the messinian salinity crisis late miocene is one of the most fascinating paleoceanographic events in the recent geological history of the mediterranean sea defining a time when it partly or nearly completely dried out however the relative roles of tectonic processes and sea level changes as triggers for restriction and isolation of the mediterranean sea from the open ocean are still under debate in this study we present a detailed pollen dinoflagellate cyst dinocyst and magnetic susceptibility analysis of a sequence of late neogene between ca 7 3 and 5 2 ma marine sediments from the montemayor 1 core lower guadalquivir basin southwestern spain which provides a continuous record of paleoenvironmental variations in the atlantic side of the betic corridors during the late miocene our results show that significant paired vegetation and sea level changes occurred during the messinian likely triggered by orbital scale climate change important cooling events and corresponding glacio eustatic sea level drops are observed in this study at ca 5 95 and 5 75 ma coinciding with the timing and duration of oxygen isotopic events tg32 and tg22 20 recorded in marine sediments worldwide it is generally accepted that the onset of the messinian salinity crisis began at ca 5 96 0 02 ma therefore this study suggests that the restriction of the mediterranean could have been triggered at least in part by a strong glacio eustatic sea level drop linked to a climate cooling event occurring at the time of initiation of the messinian salinity crisis

the use of cyclic stratigraphic pattern of peridinioid and gonyaulacoid dinoflagellate cysts in differentiating potential thick monotonous carbonate reservoirs a possible ecostratigraphic tool under test abstract the current work used the conventional peridinioid gonyaulacoid ratio p g to devise a new concept of dinoflagellate cyst zonation called the dinoflagellate ecological zone dez which is based here on the peridinioid ecological zone pez and gonyaulacoid ecological zone gez the pez and gez were used successfully to further divide the thick monotonous carbonate succession mid cenomanian to campanian in q 72 1x well in the eastern desert of egypt into smaller ecozones pez and gez are practical and easy to use in subdividing large conventional biozones of the carbonate reservoirs into distinguishable smaller ecozones when a finer resolution is necessary on a reservoir scale for production demands this tool is suggested to be used in the hydrocarbon exploration industry with minimum knowledge of the taxonomy of the dinoflagellate cysts the proposed pez and gez are related to local ecological conditions within the basin hydrocarbon field i e can be traced out laterally in an intra basinal scale this tool can be applied to any carbonate reservoirs in any petroliferous basin worldwide moreover the p g ratio the relative abundances of the dinoflagellate cyst assemblages and other palynological parameters were used successfully to reveal the palaeodepositional settings of the identified pez and gez alternating transgressive and regressive phases were identified although a dissimilar species composition is observed in each of these ecozones environments were interchanging between the regressive marginal marine to proximal inner neritic and the transgressive distal inner to middle shelf settings three peridiniacean dinoflagellate cyst peaks were recorded the middle cenomanian subtilisphaera peak the middle coniacian isabelidinium chatangiella and manumiella peak and the middle santonian isabelidinium peak

the volcanic history of central elysium planitia implications for martian magmatism abstract central elysium planitia cep is located south of elysium mons back to the era of the viking orbiters clues accumulated in favor of recent volcanism in relation with ground water release and the formation of long sub parallel fissures four aqueous flood channel systems emanate from linear fissures recent eruptions of low viscosity lavas originate from these fissures and from low shield volcanoes the objective of this paper is to constrain the volcanic history of this region and to determine the chronological relationships with fluvial erosional processes new observations e g new shield volcanoes and one new fluvial event are summarized on a context map thirty five surfaces have been dated from the count of about 15 000 impact craters ages have been cross checked with relative stratigraphy when possible a probabilistic approach has been introduced to compare similar ages and define periods of volcanic activity our results confirm that some volcanic features are extremely recent 2 my active periods are found at 2 5 3 my 4 3 my 13 5 16 2 my 19 my 21 32 my 58 my 71 my 85 95 my 134 my 173 my and 234 my not excluding the possibility that some of the gaps would be filled with additional crater counts the volcanic activity thus extended for at least the last 250 my the lava volumes have been estimated from the topographic modeling of the floor of depressions filled up by volcanic products including the volumes of several large crater cavities buried under lavas 20 of the total volume our new estimation of the total lava volume is 1 5 0 2 10 5 km 3 this value corresponds to an average thickness of one hundred meters of lavas for the young volcanic plain as a consequence the total eruption rate at cep defined as the total volume of lava divided by the time of emplacement 1 4 10 2 1 8 10 2 m 3 s is lower than values typically estimated for terrestrial hot spots or large igneous provinces suggesting longer inactive periods the concept of mantle plumes responsible for terrestrial flood volcanism may not be applicable to the case of cep and the mechanism proposed in schumacher and dreuer 2007 offers a plausible alternative to explain our observations

elysium planitia lava flows crater count chronology and geological implications mars global surveyor mgs and viking images allow analysis of chronological and geological relations among lava flows in southern elysium planitia based on crater populations mgs and viking images clearly show morphological features of lava flows with some extremely sparsely cratered young flow units atop somewhat older surfaces there is no evidence of substantial dust mantling on the young flows and hence we infer that the crater populations date not sediment accumulation but the lava flows themselves the youngest flows have some of the lowest crater densities that we have seen on mars some 1 of lunar mare values at crater diameters below about 180 to 500 m we infer that thin scattered volcanic flows some tens of meters thick have been emplaced atop stratigraphic units within the last 100 myr and possibly within the last 10 myr volcanism is thus a continuing process in the recent geologic history of mars and this must constrain geophysical models of the planet

breaching of mustang island in response to the 8 2 ka sea level event and impact on corpus christi bay gulf of mexico implications for future coastal change the results from an investigation of the coupled mustang island corpus christi bay complex gulf of mexico shows that the island was eliminated as an effective salinity barrier between 8 86 and 8

messinian climate change and erosional destruction of the central european alps comment and reply reply in his comment molenaar argues that foreland sedimentation is determined by accommodation space not sediment yield and therefore our methodology of measuring sediment volume does not actually measure erosional fluxes from the alps using sediment volumes to estimate erosion is always a risky

new insights on the sorbas basin se spain the onshore reference of the messinian salinity crisis the sorbas basin is the land reference of the messinian salinity crisis msc that affected the mediterranean sea in the latest miocene its stratigraphy has been re visited using calcareous nannofossils and planktonic foraminifers which provide a reliable biostratigraphic frame and lead to particularly specify the relationships between the sorbas and zorreras members with yesares evaporites the evaporites overlie a shallowing upward sequence ending with the deposition of the reef unit and terminal carbonate complex tcc on the periphery of the basin the reefal carbonates of the tcc are overlain by clastic deposits that are foreset beds of post msc gilbert type fan deltas developed on the northern edge of the basin these sedimentary structures are separated from reefal carbonates and the reef unit by the messinian erosional surface mes the various facies of the sorbas member have been correlated with the bottomset beds of the gilbert type fan deltas despite some differences in palaeobathymetry in the southeastern periphery of the basin the mes separates the sorbas member from the yesares gypsums in the central part of the basin a hiatus characterizes the contact between these members the zorreras member postdates the msc and entirely belongs to zanclean its white lago mare layers are lagoonal deposits the fauna of which is confirmed to result from mediterranean paratethys high sea level exchange after the post msc marine reflooding of the mediterranean basin this study allows to re assert the two step scenario of the msc clauzon et al 1996 with the following events at 5 971 5 600 ma minor sea level fall resulting in the desiccation of this peripheral basin with secondary fluctuations at 5 600 5 460 ma significant subaerial erosion or lack of sedimentation caused by the almost complete desiccation of the mediterranean sea instantaneous marine reflooding accepted at 5 460 ma followed by continuing sea level rise

variations of elastic plate thickness at continental thrust belts after examining 15 reliable estimates of the elastic thickness of the lithosphere where it underthrusts mountain belts in europe asia and the americas we conclude that the strength of continental lithosphere as a function of depth must be very different from that of oceanic lithosphere depending on the state of stress continental lithosphere may be either very much stronger or very much weaker than would be predicted for oceanic lithosphere of the same thermal age we explain this observation as the result of two competing effects a thicker thermal plate beneath the continents which allows a deeper elastic ductile transition for plates more than 100 million years old and a low activation energy for ductile creep in the continental crust which leads to massive failure of the upper elastic lithosphere at high bending stresses the 100 km values for elastic plate thickness of billion year old lithosphere require a thermal plate thickness of at least 250 km the magnitude of apparent thinning of the elastic plate at high stress is consistent with that calculated from a simple yield envelope which includes a ductile zone in the lower crust the low yield strength of continental materials leads to correlations between effective elastic plate thickness and all of the following dip of the underthrust plate radius of curvature of the thrust front in map view and total length of the mountain belt using insight derived from laboratory experiments on the buckling of spherical shells and drawing analogies with the geophysical characteristics of oceanic subduction zones we arrive at the following sequence of causes and effects the primary variable is the dip of the downgoing plate presumably prescribed by its own excess mass and pressure exerted by dynamic flow in the mantle where this dip is steep the rigidity of the plate is weakened due to inelastic yielding the weakened plate can then buckle at small wavelengths into short arcuate mountain belts thus we believe that the mantle ultimately controls the pattern of surface tectonics but that the nonelastic rheology of the lithosphere is the mechanism by which that control is imposed

tectonic control for evaporite formation in wuyang sag southern north china basin abstract there is a wide distribution of thick evaporites in the he21 and he1 members of the wuyang sag southern north china basin based on drilling data previous researchers have analyzed the formation mechanism of evaporites in wuyang sag and considered that their origination stems from the insufficient provenance and dry climate of the area however other researchers have suggested that the qinling dabie mountains on the southern part of wuyang sag acted as a stable source material throughout the deposition period of the sag these contrasting hypotheses indicate that further investigation is needed to clearly identify the evaporite genesis mechanism in wuyang sag using both seismic and geologic data this paper analyzes the impact of the uplift structure of the wuyan sag area on evaporite formation this analysis is based on restoration of the southern boundary of the sag in the deposition period with respect to the largest strike slip fault taking the erosion of the lower tertiary strata at the southern boundary of the sag greatest tectonic activity as the starting point of this study and the movement of the nw strike slip fault at the eastern part of the sag the following conclusions were drawn 1 the end stage of deposition of the he22 member of the hetaoyuan formation was an important period in the base level transition for the wuyang sag during the depositional period from the he3 member to the he22 member the sag gradually expanded as the base level was rising in the depositional period from the he21 member to the he1 member the sag gradually shrank and the base level was lowered due to the influence of structural uplift in the meantime inside the sag the left lateral strike slip fault at the basement became active again and caused the eastern area of the strike slip fault to be uplifted in the depositional period from the he21 member to deposition of the liaozhuang formation 2 the structure uplift during the depositional period from the he3 member to the he22 member blocked part of the provenance to infill the wuyang sag therefore this activity resulted the sag becoming closed or semi closed leading to the deposition of evaporites

evidence for recent volcanism on mars from crater counts impact craters help characterize the age of a planetary surface because they accumulate with time they also provide useful constraints on the importance of surface erosion as such processes will preferentially remove the smaller craters earlier studies of martian crater populations revealed that erosion and dust deposition are important processes on mars they disagreed however on the age of the youngest volcanism these earlier studies were limited by image resolution to craters larger than a few hundred metres in diameter here we report an analysis using new images obtained by the mars global surveyor spacecraft of crater populations that extend the size distribution down to about 16 m our results indicate a wide range of surface ages with one region lava flows within the arsia mons caldera that we estimate to be no older than 40 100 million years we suggest that volcanism is a continuing process on mars

identification of arid phases during the last 50 cal ka bp from the fuentillejo maar lacustrine record campo de calatrava volcanic field spain geochemical element analysis molecular analysis of organic compounds physical palynological mineralogical and sedimentary facies analysis were performed to characterise the sedimentary record in fuentillejo maar lake in the central spanish volcanic field of campo de calatrava in order to reconstruct the palaeoenvironmental and palaeoclimatic processes which controlled vegetation patterns and deposition of different sedimentary facies the upper 20 m of core fuent 1 show variations in clastic input water chemistry vegetation and organic fraction sources in the lake throughout the late pleistocene and holocene the temporal framework provided by 14c accelerator mass spectrometry dating allows assigning the sequence to the last 50 cal ka bp arid phases identified in the fuent 1 sequence are correlated to heinrich events he and to stadials of the dansgaard oeschger d o cycles siliciclastic facies with high magnetic susceptibility values high juniperus pollen content a low paq index aquatic macrophysics proxy index a decrease in the relative percentage of the n c27 and an increase in the n c31 alkanes are indicative of arid and colder climatic events related to he 2 he 1 and the younger dryas yd similar short cold and arid phases during the holocene were identified at 9 2 8 6 7 5 7 and 5 5 5 cal ka bp in dolomite mud facies the pollen data show an increase in the herbs component mainly chenopodiaceae artemisia and ephedra steppe taxa a low paq index a decrease in the relative percentage of the n c27 alkane and an increase in the n c31 alkane are also observed this facies was probably the result of lower lake levels and more saline alkaline conditions which can be interpreted as linked to arid warm periods these warm and arid phases were more frequent during marine isotope stage mis 3 and the interstadials of mis 2 he 4 he 2 he 1 and the yd in core fuent 1 were immediately followed by increases of warm steppe pollen assemblages that document rapid warming similar to the d o cycles but do not imply increasing humidity in the area fuentillejo hydrology is controlled by changes in the atmospheric and oceanic systems that operated on the north atlantic region at millennial scale during the last 50 cal ka bp copyright 2009 john wiley sons ltd

paleoenvironmental evolution of the eastern mediterranean during the messinian constraints from integrated microfossil data of the pissouri basin cyprus abstract integrated data of calcareous nannofossils as well as planktonic and benthic foraminifera from the pissouri motorway section on cyprus allow the reconstruction of surface and bottom water paleoenvironments of the eastern mediterranean during the interval preceding the messinian salinity crisis msc contrary to deeper water locations where benthic foraminifera faunas are suppressed or absent just after the tortonian messinian boundary sediments deposited at intermediate water depths do contain benthic assemblages from the earliest messinian onwards a development towards increasingly unfavourable paleoenvironments is reflected in the planktonic and benthic microfossil records of the pissouri section and proceeds with rather discrete time steps that can be correlated to sequences throughout the mediterranean shortly after the tortonian messinian boundary a transition is recorded in the sedimentology and the open marine deeper water taxa disappear from the benthic foraminifera assemblages subsequently the diversity of all fauna groups diminishes the changes recorded at species level in both surface water and sea floor dwelling taxa suggest decreasing circulation of the bottom waters associated with changes in the surface waters most likely due to increasing stratification from 6 73 ma onwards our data indicate a prominent change to more restricted conditions and increasing salinity at the sea floor together with intermittently rising surface water salinity the dominance of oligotypic and monospecific assemblages and the frequent shifts in assemblage compositions of all microfossil groups indicate severely stressed environments after 6 4 ma probably related to increased salinity the major changes in paleoenvironmental conditions including oxygen deprivation due to stagnation and hypersalinity can be explained by hydrographical changes in the mediterranean basin which are probably caused by tectonic movements in the rif corridor acting in concert with astronomical cyclicity evaluation of the paleodepth proxies indicates that the depth of the pissouri basin remained rather constant at 300 500 m with a minimum of 200 m until deposition of the barre jaune the transitional interval towards the evaporites and that early shallowing to neritic depths as was proposed before is highly unlikely

timing and progression of climatic tectonic and glacioeustatic influences on the messinian salinity crisis abstract new palynological analysis of the continuous upper neogene sequence from the rifian corridor at sale morocco permits the deconvolution of climatic tectonic and eustatic control on the messinian salinity crisis via two indices 1 a distance from shore index based on dinoflagellate cyst versus pollen distribution and 2 a land climate index based on detailed pollen analysis this new pollen analysis indicates that the messinian salinity crisis 6 8 ma to 5 3 ma was not associated with major climate change detailed analyses of dinoflagellate cyst ecology at sale correlated to the sale 18o record show that initial shoaling of the rifian corridor after 7 3 ma primarily resulted from tectonic uplift however from 6 5 ma to 5 4 ma the rifian corridor was sufficiently shallow to have experienced significant restriction of atlantic inflow during at least four small amplitude glacioeustatic lowstands at 5 4 ma abrupt increase in the ratio of continental versus marine derived palynomorphs indicates that restriction intensified as tectonic uplift significantly outpaced gradual glacioeustatic rise despite eustatic rise at 5 32 ma the sale palynological data show that the rifian corridor experienced a second major drop in relative sea level tectonic uplift or increased sedimentation therefore termination of the messinian salinity crisis was probably associated with a breach elsewhere along the gibraltar arc

chronology causes and progression of the messinian salinity crisis the messinian salinity crisis is widely regarded as one of the most dramatic episodes of oceanic change of the past 20 or so million years 1 3 earliest explanations were that extremely thick evaporites were deposited in a deep and desiccated mediterranean basin that had been repeatedly isolated from the atlantic ocean1 2 but elucidation of the causes of the isolation whether driven largely by glacio eustatic or tectonic processes have been hampered by the absence of an accurate time frame here we present an astronomically calibrated chronology for the mediterranean messinian age based on an integrated high resolution stratigraphy and tuning of sedimentary cycle patterns to variations in the earth s orbital parameters we show that the onset of the messinian salinity crisis is synchronous over the entire mediterranean basin dated at 5 96 0 02 million years ago isolation from the atlantic ocean was established between 5 59 and 5 33 million years ago causing a large fall in mediterranean water level followed by erosion 5 59 5 50 million years ago and deposition 5 50 5 33 million years ago of non marine sediments in a large lago mare lake sea basin cyclic evaporite deposition is almost entirely related to circum mediterranean climate changes driven by changes in the earth s precession and not to obliquity induced glacio eustatic sea level changes we argue in favour of a dominantly tectonic origin for the messinian salinity crisis although its exact timing may well have been controlled by the 400 kyr component of the earth s eccentricity cycle

precise 40ar 39ar dating of volcanic tuffs within the upper messinian sequences in the melilla carbonate complex ne morocco implications for the messinian salinity crisis the melilla carbonate complex ne morocco is the only area of the paleo mediterranean sea where volcanic activity was present throughout most of the messinian 40ar 39ar dating of volcanic tuffs interbedded within the upper messinian sedimentary deposits known as the terminal carbonate complex tcc yields accurate ages of paleoenvironmental and sea level changes related to the messinian salinity crisis the new chronologic data 1 provide an average of 5 95 5 99 ma for the base of the tcc thus being synchronous with the onset of the messinian salinity crisis 2 demonstrate for the first time that the basal unconformity of the tcc does not represent a hiatus of long duration 3 define a precise time line at 5 87 0 02 ma 2 corresponding to sedimentary rocks exhibiting a lateral transition between continental and marine deposits typical of the tcc and 4 yield evidence that emersion of the melilla platform during deposition of the tcc is partly related to tectono magmatic activity an erosional surface capping the tcc deposits in the melilla basin is related to the major messinian mediterranean drawdown the duration of the hiatus associated with this surface is estimated to be at most 450 kyr but is probably shorter

pliocene paleoclimatic reconstruction using dinoflagellate cysts comparison of methods the application of quantitative and semiquantitative methods to assemblage data from dinoflagellate cysts shows potential for interpreting past environments both in terms of paleotemperature estimates and in recognizing water masses and circulation patterns estimates of winter sea surface temperature wsst were produced by using the impagidinium index ii method and by applying a winter temperature transfer function tfw estimates of summer sea surface temperature ssst were produced by using a summer temperature transfer function tfs two methods based on a temperature distribution chart act and actpo and a method based on the ratio of gonyaulacoid protoperidinioid specimens g p wsst estimates from the ii and tfw methods are in close agreement except where impagidinium species are sparse ssst estimates from tfs are more variable the value of the g p ratio for the pliocene data in this paper is limited by the apparent sparsity of protoperidinioids which results in monotonous ssst estimates of 14 26 c the act methods show two biases for the pliocene data set taxonomic substitution may force matches yielding incorrect temperature estimates and the method is highly sensitive to the end points of species distributions dinocyst assemblage data were applied to reconstruct pliocene sea surface temperatures between 3 5 2 5 ma from dsdp hole 552a and odp holes 646b and 642b which are presently located beneath cold and cool temperate waters north of 56 n our initial results suggest that at 3 0 ma wssts were a few degrees c warmer than the present and that there was a somewhat reduced north south temperature gradient for all three sites it is likely that sssts were also warmer but by an unknown perhaps large amount past oceanic circulation in the north atlantic was probably different from the present

astronomical forcing of northwest african climate and glacial history during the late messinian 6 5 5 5 ma abstract high resolution physical chemical and biological based climate proxies from the ain el beida aeb section in atlantic morocco reveal the imprint of the three main orbital parameters precession 19 23 kyr obliquity 41 kyr and eccentricity 95 125 and 400 kyr between 6 5 and 5 5 million years before present ma the precession related variations are most prominently reflected in the color reflectance and chemical composition of the sediment showing that precession minimum configurations lead to more humid climate conditions in northwest africa probably related to the atlantic system while more arid climate conditions prevailed during precession maxima in addition precession bound changes in planktonic foraminifera and calcareous nannofossil assemblages indicate that sea surface temperature sst increased during the humid phases while productivity conditions increased during the dry periods the clear imprint of the short and long term eccentricity cycles is explained by a non linear climatic response to the precession forcing with overall more humid climate conditions during eccentricity maxima the obliquity controlled variations in sst and aridity conditions concur with glacial interglacial variability that is conspicuously recorded in both planktonic and benthic 18 o records of aeb the observed warm and wet climates during interglacial periods most likely reflect the direct ice driven thermal response to the reduced ice sheets and more active atlantic depressions similar as during the pliocene and pleistocene obliquity controlled variations in the planktonic and benthic carbon isotope 13 c records of aeb are inversely related to the oxygen isotope records with more depleted values during glacial stages although with a small lag the close correspondence between the 13 c records of aeb and other open ocean sites i e sites 982 and 926 may therefore point to large scale glacial controlled variations in the deep sea carbon reservoir superimposed on the orbital variations the imprint of the onset of the messinian salinity crisis can be traced by a marked 1 0 negative excursion in planktonic 13 c at 6 0 ma followed by a prominent peak in ti al at 5 97 ma

lago mare episodes around the messinian zanclean boundary in the deep southwestern mediterranean abstract we present a high resolution analysis of planktonic foraminifers calcareous nannofossils ostracods dinoflagellate cysts and pollen grains in four sequences from dsdp odp holes in the southwestern mediterranean alboran and balearic basins 976b 977a 978a and 134b encompassing the previously defined messinian zanclean boundary the study focuses on 1 the marine reflooding which closed the messinian salinity crisis prior to the zanclean gssp 2 the nature of the lago mare in the deep basins indicated by paratethyan dinoflagellate cysts which appears to comprise several paratethyan influxes without climatic control and 3 the depositional context of the youngest messinian evaporites which accumulated in a marine environment relatively close to the palaeoshoreline isolation of the aegean basin during the paroxysmic second step of the crisis is considered to have stored paratethyan waters which may then have poured into the mediterranean central basins after deposition of the evaporitic sequence

a numerical study of the climate response to lowered mediterranean sea level during the messinian salinity crisis abstract roughly six million years ago tectonic movements isolated the mediterranean sea ms from the atlantic ocean an event known as the messinian salinity crisis msc subsequent evaporative drawdown of the ms resulted in a subaerial depression with a depth between 1500 and 2500 m in this study five simulations are run using the national center for atmospheric research ncar community atmosphere model version 3 cam3 configured with the slab ocean model three simulations have been performed to test the climate impacts to desiccation and to changing the ms base level in this study the ms base level is reduced 750 m in the half land simulation hl and 1500 m in the lowered sea ls and lowered land ll simulations the hl and ll simulations differ from the ls in that the surface is converted to land representing the complete desiccation of the ms the substantial ms depression generates planetary scale atmospheric waves responsible for significant climate effects throughout the northern hemisphere a notable deepening of the aleutian low and a significant equatorward shift in the atlantic jet stream are evident in djf vertical ascent at the northern margin of the ms results in a 1 5 2 5 mm day 1 precipitation anomaly in the ls run over the alps consistent with proxy data annual mean area averaged ms evaporation is slightly higher than control conditions except when salinity is a substantial barrier to evaporation our results suggest that a partially filled basin cannot exist in equilibrium and the ms must either be partly connected to the atlantic ocean or completely desiccated base level lowering which alters the water budget must be taken into account when considering the freshwater budget during the msc

low degree mantle convection with strongly temperature and depth dependent viscosity in a three dimensional spherical shell 1 a series of numerical simulations of thermal convection of boussinesq fluid with infinite prandtl number with rayleigh number 10 7 and with the strongly temperature and depth dependent viscosity in a three dimensional spherical shell is carried out to study the mantle convection of single plate terrestrial planets like venus or mars without an earth like plate tectonics the strongly temperature dependent viscosity the viscosity contrast across the shell is 10 5 makes the convection under stagnant lid short wavelength structures numerous cylindrical upwelling plumes are developed because of the secondary downwelling plumes arising from the bottom of lid this convection pattern is inconsistent with that inferred from the geodesic observation of the venus or mars additional effect of the stratified viscosity at the upper lower mantle the viscosity contrast is varied from 30 to 300 are investigated it is found that the combination of the strongly temperature and depth dependent viscosity causes long wavelength structures of convection in which the spherical harmonic degree l is dominant at 1 4 the geoid anomaly calculated by the simulated convections shows a long wavelength structure which is compared with observations the degree one l 1 convection like the martian mantle is realized in the wide range of viscosity contrast from 30 to 100 when the viscosity is continuously increased with depth at the lower mantle

mediterranean sea level variations during the messinian salinity crisis 1 the mediterranean basin has not always been connected to the atlantic ocean during the messinian salinity crisis msc the mediterranean sea became progressively isolated by a complex combination of tectonic and glacio eustatic processes when isolated the mediterranean water level depends on the hydrological flux and is expected to vary significantly the amplitude and number of large water level fluctuations in the isolated mediterranean is still controversial despite numerous geological investigations the observation of 3 5 surfaces of erosion in the nile delta eastern basin provides new elements for understanding the dynamics of the msc our model demonstrates that numerous water level falls of short duration may explain the preservation of a discontinuous river profile at 500 m and 1500 m in the western basin as well as the existence of deep surfaces of erosion in the eastern basin

how much did climate force the messinian salinity crisis quantified climatic conditions from pollen records in the mediterranean region the latest miocene 5 96 to 5 33 ma is characterised by an outstanding event the desiccation of the mediterranean sea messinian salinity crisis it has been suggested that this was caused by a tectonic event with no climatic change playing a role in desiccation quantifying the climate of the region during this period will help support or refute this hypothesis an effective method for reconstructing the climate from neogene pollen data is the climatic amplitude method based on the modern climatic requirements of plants to interpret fossil data it has been conceived especially for periods devoid of modern vegetation analogue twenty messinian to lower zanclean pollen sequences are now available in the peri mediterranean region most of them do not cover the whole messinian interval particularly those along the mediterranean shorelines where sedimentation was interrupted during the sea s desiccation in contrast sedimentation was almost continuous in such areas as the atlantic side of morocco along the adriatic coast including the po valley and to a lesser extent the black sea the mediterranean sites nonetheless provide a reliable if not a discontinuous record of vegetation variability in time and space a first examination of the pollen diagrams reveals a high regional variability controlled by local conditions and throughout the interval a southward increase in herb pollen frequency in contrast to the tree pollen frequency this indicates that open and probably dry environments existed in the southern mediterranean region prior to during and after the salinity crisis trees developed in areas close to mountains such as in the po valley in cerdanya and in the black sea region most variations observed in the pollen diagrams are constrained by fluctuations of pinus pollen amounts indicating eustatic variations climatic quantification from pollen data does not show obvious climatic changes due to the desiccation of the mediterranean sea especially in the dry and warm southwestern mediterranean area sicily southern spain and north africa at maccarone along the adriatic sea a decrease in temperatures of the coldest month and less importantly a decrease in mean annual temperatures corresponding to a drastic vegetation change are reconstructed these temperature variations are assumed to be controlled by regional environmental changes massive arrival of waters in this basin rather than to reflect cooling because some authors link the second phase of evaporite deposition to a period of global warming some migrations of plants probably occurred as a response to mediterranean desiccation but the climatic contrast which has probably existed at that time between the central mediterranean and the peripheral areas might be amplified climatic reconstruction from pollen data in the western mediterranean area shows that climate is not the direct cause of the mediterranean desiccation as the mediterranean region had experienced continuously high evaporation long before the crisis therefore the main factor leading to this event seems to be the successive closures of the betic and rifian corridors isolating the mediterranean sea from the atlantic ocean

subsurface seepage of seawater across a barrier a source of water and salt to peripheral salt basins many of the great phanerozoic salt basins share a common paleogeography in which a deep lake or sea is separated from the ocean by a narrow barrier examples include the aptian evaporites of the south atlantic rift basins and the messinian salt deposits of the mediterranean sea and the north caspian depression marine transgressions over the barrier have been proposed as the origin for saline conditions in these basins we test an alternate hypothesis that subsurface seepage of seawater through the barrier was a significant source of water influencing both water level and water composition our model permits flux of water and salt into and out of the basin via 1 seepage through the barrier 2 evaporation from the water surface 3 rainfall and or rivers and 4 incorporation into basin sediments our investigation focuses on three settings a modern analog in the gregory rift of northern kenya the messinian mediterranean basin and the early cretaceous aptian salt basins of the south atlantic we test our model through a numerical simulation applying reasonable values for the dimensions of the barrier differences in water level and hydraulic conductivities to calculate flow rates through the barrier modeling results indicate that flux of seawater through a barrier to a peripheral basin ranges from the dominant component of lake water to insignificant depending on the climate size of the peripheral basin and hydraulic conductivity of the barrier the flux of salt is significant over the full range of modeled hydraulic conductivities producing brines in the peripheral lake and or sea within 0 5 m y in most cases this demonstrates that seepage through the barrier can account for lithologic and organic geochemical evidence for saline water conditions and that marine transgressions across the barrier are not necessary to explain the apparent high salinities

verifying single station seismic approaches using earth based data preparation for data return from the insight mission to mars abstract the planned insight mission will deliver a single seismic station containing 3 component broadband and short period sensors to the surface of mars in 2016 while much of the progress in understanding the earth and moon s interior has relied on the use of seismic networks for accurate location of sources single station approaches can be applied to data returned from mars in order to locate events and determine interior structure in preparation for the data return from insight we use a terrestrial dataset recorded at the global seismic network station bfo located at the black forest observatory in germany to verify an approach for event location and structure determination based on recordings of multiple orbit surface waves which will be more favorable to record on mars than earth due to smaller planetary radius and potentially lower background noise with this approach applied to events near the threshold of observability on earth we are able to determine epicentral distance within approximately 1 corresponding to 60 km on mars and origin time within 30 s with back azimuth determined from rayleigh wave polarization absolute locations are determined generally within an aperture of 10 allowing for localization within large tectonic regions on mars with these locations we are able to recover earth mantle structure within 5 the insight mission requirements for martian mantle structure using 1d travel time inversions of p and s travel times for datasets of only 7 events the location algorithm also allows for the measurement of great circle averaged group velocity dispersion which we measure between 40 and 200 s to scale the expected reliable frequency range of the insight data from earth to mars data using the terrestrial data we are able to resolve structure down to 200 km but synthetic tests demonstrate we should be able to resolve martian structure to 400 km with the same frequency content given the smaller planetary size

tectonic control on the late stage exhumation of the aar massif switzerland constraints from apatite fission track and u th he data 1 we examine the hypothesis that pliocene exhumation of the external massifs in the central alps is controlled by climatic change new thermochronological data from the western gastern aar massif are used to investigate the timing extent and reasons for neogene exhumation our data reveal that exhumation was constant with 0 5 km ma over the last 10 ma in the north in the southern part exhumation was of the same order until 3 5 ma but then increased gradually toward the south to values of up to 1 2 km ma resulting in overall northward tilting of the western aar massif we explain this accelerated exhumation in the south after 3 5 ma mainly by tectonic denudation in the footwall of the rhone simplon fault and discuss changes in deep crustal configuration which may have triggered south directed normal faulting we propose that the rhone river was structurally trapped by the rhone simplon normal fault zone which additionally enhanced erosion in the southern section of the aar massif climatic forcing may have an impact in the very late stage of exhumation due to alpine glaciation in the late pliocene

selective transport of palynomorphs in marine turbiditic deposits an example from the ascension monterey canyon system offshore central california abstract the pollen assemblage of a deep sea core 15g collected at lower bathyal depths 3491 m on a levee of monterey canyon off central california was investigated to gain insights into the delivery processes of terrigenous material to submarine fans and the effect this transport has on the palynological record thirty two samples were obtained down the length of the core 19 from hemipelagic and mixed mud deposits considered to be the background record and 13 others from displaced flow deposits the pollen record obtained from the background samples documents variations in the terrestrial flora as it adapted to changing climatic conditions over the last 19 000 cal yrs bp a q mode cluster analysis defined three pollen zones a glacial pollen zone ca 20 000 17 000 cal yr bp an overlying transitional pollen zone ca 17 000 11 500 cal yr bp and an interglacial pollen zone ca 11 500 cal yr bp to present another q mode cluster analysis of both the background mud and flow deposits also defined these three pollen zones but four of the 13 turbiditic deposits were assigned to pollen zones older than expected by their stratigraphic position this was due to these samples containing statistically significant fewer palynomorphs than the background muds as well as being enriched 10 35 in some cases in hydraulically efficient pinus pollen a selective bias in the pollen assemblage such as demonstrated here may result in incorrect interpretations e g climatic shifts or environmental perturbations based on the floral record indicating turbiditic deposits should be avoided in marine palynological studies particularly in the case of fine grained flow deposits that may not be visually distinct granulometry and grain size frequency distribution curves may not be enough to identify these biased deposits determining the relative abundance and source of displaced shallow water benthic foraminifera entrained in these sediments serves as an excellent additional tool to do so

palynomorph evidence for tropical climate stability in the gulf of papua papua new guinea over the latest marine transgression and highstand 14 500 years bp to today abstract three sediment cores mv 41 mv 46 and md 50 from the gulf of papua gop papua new guinea were analyzed to assess changes in climatic oceanographic and sedimentological conditions over the last 14 5 kyr palynomorphs which were isolated from sediment core samples were collected at approximately 0 5 m intervals using a strong acid and oxidant md 50 non oxidant mv 41 mv 46 procedure radiocarbon 14c stable isotope geochronology magnetic susceptibility stable isotope analysis md 50 only oxygen 18 18o and carbon 13 13c and clay mineral maturity analysis were also completed for each core palynological data indicate that climatic conditions at sea level have remained warm wet and stable for the past 14 5 kyr with sea surface temperatures in the gop above 14 c potential decreases in vegetative cover marked the younger dryas interval 12 5 11 5 kyr bp as indicated by reduced pollen and spore recovery the end of the latest marine transgression and the subsequent return to eustatic sea level highstand is clearly delineated by increases in marine palynomorph recovery and decreases in mangrove pollen at approximately 5 kyr bp an increase in seasonality and potential el nino southern oscillation variability is observed in md 50 s oxygen isotope results at 5 kyr bp this is not supported by the palynomorph record likely because of the sampling interval and dilution by tropical pollen flora which indicates stable climatic conditions throughout the last 14 5 kyr sediment transport pathways in the gop remained fairly constant throughout the time interval which is supported by the lack of major changes in palynomorph assemblage composition

mechanism of the giant seimareh landslide iran and the longevity of its landslide dams seimareh landslide sl is globally recognized as one of the largest rock mass movements in the world it is located along the border of ilam and lorestan provinces in southwest iran in the heart of the zagros mountain range there are controversial findings about the mechanism of the landslide formation this field work study reviewed the possible mechanisms of failure and analyzed post failure geomorphic features drainage pattern disturbance in the depositional region and consequent dammed lake formation are among the most significant characteristics of these features seimareh jaidar and balmak are three large landslide dammed lakes the present study analyzed the processes responsible for the formation and erosion of the jaidar and seimareh landslide dams using the available annual sedimentation and field measurements of the sediment deposited in these lakes the results showed that the sl dam has been formed about 935 years after the landslide event detailed field investigations indicated a specific hydro morphological condition in the landslide area the results implied that the main causes of the failure were probably the particular hydro morphological characteristic of the landslide source area together with the enormous eroding energy resulted from merging of two high flow rivers which eroded the base of the southern flank of kabir kuh mountain however the unusual size of the landslide suggests that an external factor e g a huge earthquake might have triggered the failure

late neogene erosion of the alps a climate driver as with many mountain belts globally the alps have seen a large increase in sediment yield in the late neogene the hypothesis that this increase results from climate change impacts on erosion rate over the past 5 ma is testable given the extensive work completed in the alps sediment budgets thermochronology based cooling rates and estimates of modern rock uplift and erosion in the western alps are reviewed to search for correlation in space and time that might fingerprint climatic events major increases in sediment yield are apparent starting in the late messinian 5 5 mya and accelerating toward the present day this suggests the occurrence of a series of climatic changes that increased erosion rates even as tectonic processes appear to have slowed or stopped at present tight correlations in time are difficult to establish and there remain open questions about the role of tectonics in the coupled system

climatic or tectonic control on organic matter deposition in the south china sea a lesson learned from a comprehensive neogene palynological study of iodp site u1433 abstract palynomorphs and other organic particles are basic key components of palynofacies yet quantitative analyses of all types are rarely used together to investigate organic matter assemblage changes and evaluate the driving forces behind the observed changes in this paper eight organic walled microfossil and particle morphologies sporopollen pediastrum concentricystes fungi dinoflagellate cysts structured amorphous organic matters stomatal apparatus and scolecodonts are tabulated and their concentrations and fluxes are evaluated over the past 17 million years ma in sediments recovered from the south china sea at international ocean discovery program iodp site u1433 overall these morphologies show roughly similar increasing trends but with different levels of fluctuations the uniform increase in all morphologies at 8 ma named the 8 ma event is the most notable feature of the past 17 ma to explain the trend and because these various organic matters reflect various environmental conditions we argue that the uniformity of the signal implies that tectonically driven basin and drainage evolution played the key role rather than paleoclimate asian summer monsoon the 8 ma event was likely triggered by the onset of the mekong river in its present location although the role of monsoon evolution cannot be excluded completely

tissint martian meteorite a fresh look at the interior surface and atmosphere of mars tissint morocco is the fifth martian meteorite collected after it was witnessed falling to earth our integrated mineralogical petrological and geochemical study shows that it is a depleted picritic shergottite similar to eeta79001a highly magnesian olivine and abundant glass containing martian atmosphere are present in tissint refractory trace element sulfur and fluorine data for the matrix and glass veins in the meteorite indicate the presence of a martian surface component thus the influence of in situ martian weathering can be unambiguously distinguished from terrestrial contamination in this meteorite martian weathering features in tissint are compatible with the results of spacecraft observations of mars tissint has a cosmic ray exposure age of 0 7 0 3 million years consistent with those of many other shergottites notably eeta79001 suggesting that they were ejected from mars during the same event

orbital signatures in a late miocene dinoflagellate record from crete greece abstract a high resolution palynological study of the cyclically bedded faneromeni section upper tortonian lower messinian on crete greece is presented this study aims to recognize orbitally driven variations in the palynological record and to validate the age model based on the astronomical calibration of the sedimentary cycles four palynology based environmental proxies were utilised using interpretations of fossil dinoflagellate associations based on modern ecological characteristics cross spectral analysis between the proxy records and astronomical target curve the 65 n summer insolation yielded in most cases significant spectral power and coherence in the precession and or obliquity frequency bands precession controlled variations in the proxy records are related to lithology and indicate that maxima in continental input and minima in sea surface salinity coincide with sapropel formation the influence of obliquity is most clearly reflected in the index of continental versus marine palynomorphs s d the absence of a distinct time lag relative to obliquity indicates that the 41 kyr component in continental input is controlled by oscillations in regional mediterranean climate rather than by glacial cyclicity phase relations in the different astronomical frequency bands of the spectrum as compared with the mediterranean pliocene essentially confirm the validity of the miocene astronomical time scale finally a major non cyclic change in the palynological assemblage at 6 68 ma indicates enhanced salinity and decreased river discharge this shift coincides with a significant drop in sedimentation rate informally termed the early messinian sediment starvation event

three dimensional simulations of the southern polar giant impact hypothesis for the origin of the martian dichotomy we demonstrate via numerical simulations that the impact of a lunar sized body with mars is capable of creating a hemispherical magma ocean that upon cooling and solidification resulted in the formation of the southern highlands and thus the martian dichotomy the giant impact may have contributed a significant amount of iron to the martian core and generated a deep thermal anomaly that led to the onset and development of the volcanism in the southern highlands our model predicts several mantle plumes converging to the south pole from the equatorial regions as well as new plumes forming in the equatorial region and also an absence of significant large scale volcanism in the northern lowlands the core heat flux evolution obtained from our numerical models is consistent with the decline of the magnetic field we argue that such a scenario is more consistent with a range of observations than a northern giant impact excavating the borealis basin for the formation of the martian dichotomy

knobby terrain on ancient volcanoes as an indication of dominant early explosive volcanism on mars determining if the mechanically weak materials of the upper crust are products of early explosive volcanism or generated by modification of extensive effusive lava flows is important for understanding the geologic and thermal history of mars we examined 75 recently identified preserved ancient volcanoes whose eruption styles are representative of early volcanism we describe a unique knobby terrain that is associated with 17 of these volcanoes this newly identified terrain is characterized by a combination of high resolution images and thermophysical and thermal infrared hyperspectral data the morphology characteristics of these knobby terrains are similar to terrestrial eroded ignimbrites and the thermophysical properties indicate that they are composed of unconsolidated fine grained materials the spectral analysis indicates that they experienced some aqueous alteration we explain the knobby terrain associated with these ancient volcanoes as the products of an early explosive volcanic phase in martian history followed by subsequent modification of these deposits

palynological evidence for early to mid holocene sea level fluctuations over the present day ningshao coastal plain in eastern china abstract sea level fluctuation in a coastal plain setting was crucial for neolithic human occupations of the ningshao coastal plain in eastern china in this study we carry out analyses using detailed palynological records of dinoflagellate cysts dinocysts freshwater algae and foraminiferal organic linings from two sediment cores hmd1501 and hmd1502 at the tianluoshan archaeological site zhejiang province eastern china brief sea level fluctuations and environmental changes on the ningshao coastal plain during the early to mid holocene were recovered by using radiocarbon chronology the results show the tianluoshan site underwent marine transgression processes and experienced warm and humid climatic conditions during the ca 10 708 5850 cal yr bp after that there was a relatively cold and dry climate marine regression processes occurred at the tianluoshan site during the ca 5850 5655 cal yr bp indicated by an abrupt increase in the cold water species of dinoflagellates especially o centrocarpum freshwater algae concentration and the ratio of pollen to dinoflagellates p d with an abrupt decrease appeared in foraminifer linings concentration marine regression processes provided an opportunity for hemudu ancestors to enter the tianluoshan site which helped create a brilliant hemudu tianluoshan culture on the ningshao coastal plain

geomorphology and kinematics of the conturrana rockslide debris flow nw sicily the conturrana rockslide debris flow involved a mass of almost 22 106 m3 of well indurated breccia with a plastic basal layer the original rock mass slid initially along a listric slip surface which required the rupture of the mass itself by internal shearing and caused the formation of a horst and graben morphology and attained a high speed then part of the mass fell from a morphological step and moved about 800 m forward in this landslide the morphological and morphometrical examination which is also based on a reconstruction of the pre landslide topography indicates that mobility was rather low when related to volume and to the control exerted by local morphology the event might have been induced by an earthquake in the 4th century

clay mineral assemblages siliciclastic input and paleoproductivity at odp site 1085 off southwest africa a late miocene early pliocene history of orange river discharges and benguela current activity and their relation to global sea level change abstract a late miocene to early pliocene sequence drilled on the continental slope of southwest africa off the orange river mouth odp site 1085 has been investigated clay mineral assemblages coarse siliciclastics and benthic foraminifer accumulation rates bfar unravel a step by step evolution of marine and continental environments closely related to sea level variations ocean circulation and global climate 1 smectite is a typical tracer of the orange river load whereas illite is mostly transported by the benguela current like chlorite and winds and kaolinite is derived from low latitudes by the poleward undercurrent and the north atlantic deep water nadw 2 increased erosion and influence of the orange river after 9 6 ma is linked to a sea level drop at a time of antarctic ice growth this has been followed by an increased seasonality of precipitation and high productivity but low oxygen content and associated dissolution of carbonates 3 increased productivity and dissolution of carbonates and coeval increase of continental aridity after 8 9 ma express a further development of the benguela current and upwelling 4 better preservation of carbonates and increased contribution of terrigenous material from northern sources at 6 9 ma are related to increased circulation of nadw after an early stage of northern hemisphere glaciation 5 increased erosion and contribution from the orange river and westward shift of the area of higher productivity from 5 9 5 8 ma to 5 3 5 2 ma are related to a significant fall of sea level and encompass the time of the entire mediterranean salinity crisis 6 short term variations of the smectite illite ratio s i and bfar suggest a major control of productivity by wind and current activities and related upwelling but may express brief variations of sea level in specific intervals before 8 9 ma and during the late messinian especially

the presence and stability of ground ice in the southern hemisphere of mars abstract we calculate new estimates of ground ice stability and the depth distribution of the ice table the depth boundary between ice free soil above and ice cemented soil below and compare these theoretical estimates of the distribution of ground ice with the observed distribution of leakage neutrons measured by the neutron spectrometer instrument of the mars odyssey spacecraft s gamma ray spectrometer instrument suite our calculated ground ice distribution contains improvements over previous work in that we include the effects of the high thermal conductivity of ice cemented soil at and below the ice table we include the surface elevation dependence of the near surface atmospheric humidity and we utilize new high resolution maps of thermal inertia albedo and elevation from mars global surveyor observations results indicate that ground ice should be about 5 times shallower than in previous predictions while results are dependent on the atmospheric humidity depths are generally between a few millimeters and a few meters with typical values of a few centimeters results are also geographically similar to previous predictions with differences due to the higher resolution of thermal inertia and the inclusion of elevation effects on humidity comparison with the measured epithermal neutron count rates in the southern hemisphere indicate that the geographic distribution of the count rate is best correlated with ground ice in equilibrium with 10 to 20 pr m precipitable micrometers column abundance of atmospheric water assuming a uniform distribution with co2 however given the uncertainties 5 to 30 pr m also may be viable this water abundance represents a longer term average over 100 to 1000 yr there is a high degree of correlation between the depth of the ice table and the epithermal count rate that agrees remarkably well with predicted count rates as a function of ice table depth these results indicate that ground ice in the upper meter of the martian soil is in diffusive equilibrium with the atmosphere since ground ice in this depth zone is expected to undergo saturation desiccation cycles with orbital variations this ice should be younger than about 500 kyr and was emplaced under similar cold and dry climate conditions of today remaining differences between the predicted depths of the ice table and those inferred from the neutron data are likely to be due to subpixel heterogeneity in the martian surface including the presence of rocks slopes and patches of soil with varying thermophysical properties

the upper miocene of the southern north sea basin northern belgium a palaeoenvironmental and stratigraphical reconstruction using dinoflagellate cysts organic walled palynomorph assemblages from the kasterlee formation in northern belgium provide new insights into the late miocene depositional history and palaeoenvironments of the southernmost north sea basin ranges of key dinoflagellate cysts constrain the unit between 7 5 and 5 32 ma that is a latest tortonian to messinian age the palynomorph assemblage is characterized amongst others by geonettia clineae an opportunistic species that thrives in mesotrophic coastal embayments with a low sediment influx this environmental setting is corroborated by the notable presence of gramocysta verricula a species with preference for shallow marine environments the occurrence of species of the fresh water green alga pediastrum indicates manifest river discharge in a near shore environment or embayment the coastal depositional environment mirrored by the palynomorphs of the kasterlee formation succeeds the distinct transgressive and fully marine environments of the underlying diest formation in the campine area the results from the palynological study combined with lithological and geophysical data show that both upper miocene formations are two distinct depositional cycles separated by an erosional or regressive phase the upper boundary of the kasterlee formation is correlated with the me2 sequence boundary at 5 73 ma the kasterlee formation is herein formally moved from the lower pliocene series to the upper miocene series the coastal environment probably characterized by a shoaling phase recorded at the border of the southern north sea basin matches the global record of regressive phases in messinian sedimentary sequences which are linked to cooling and increasing global ice volume

ancient plutonic processes on mars inferred from the detection of possible anorthositic terrains the formation of the silicate mineral anorthosite is thought to require magmatic processes that are not expected on mars because of its predominately mafic terrains localized spectral detections by the mars reconnaissance orbiter are consistent with anorthosite suggestive of ancient intrusive igneous processes similar to those active on earth