the geological isotopic botanical invertebrate and lower vertebrate surroundings of ardipithecus ramidus sediments containing ardipithecus ramidus were deposited 4 4 million years ago on an alluvial floodplain in ethiopia s western afar rift the lower aramis member hominid bearing unit now exposed across a 9 kilometer structural arc is sandwiched between two volcanic tuffs that have nearly identical 40ar 39ar ages geological data presented here along with floral invertebrate and vertebrate paleontological and taphonomic evidence associated with the hominids suggest that they occupied a wooded biotope over the western three fourths of the paleotransect phytoliths and oxygen and carbon stable isotopes of pedogenic carbonates provide evidence of humid cool woodlands with a grassy substrate

controlled implosive downhole seismic source a controlled implosive downhole seismic source having a substantially hollow closed vessel body adapted to be lowered in a borehole and means for selectively causing at least a portion of the vessel body to implode under pressure thereby producing seismic waves

probing the melt zone of kilauea iki lava lake kilauea volcano hawaii new drilling techniques were recently used to drill and core the melt zone of kilauea iki lava lake to a depth of 93 m a partial melt zone was found to exist at depths between 58 m and 89 m consisting of 40 volume percent melt downhole seismic shots detonated in and below the melt zone resulted in the first in situ measurements of seismic velocity directly through well characterized partial melt zone periodic seismic sources were used to effectively penetrate the highly fractured hydrothermal zone of the lava lake crust low velocity p wave layers or 2 0 km s were found at the surface at 40 m depth and at 90 m depth thermal convective experiments in the melt zone resulted in the first controlled in situ measurements of the interaction of water with a basaltic melt zone transient energy rates of 900 kw 980 kw m sup 2 and steady rates of 85 kw 93 kw m sup 2 were observed the full water recovery 100 high downhole steam temperatures 670 c and high energy transfer rates 93 to 980 kw m sup 2 observed in these thermal experiments are consistent with a closed cavity model where the injected water steam directly contacted basaltic melt ormore near melt in addition to understanding lava lakes these seismic and thermal experiments have applications for the location of magma bodies in the crust and for the efficient extraction of energy from these bodies less

paleosol carbonates from the omo group isotopic records of local and regional environmental change in east africa abstract pliocene and pleistocene sedimentary rocks from the omo turkana basin in east africa are well known for fossil and archeological evidence of human evolution and provide a unique opportunity to study four million years of environmental change in a rift basin this study uses carbon and oxygen isotope ratios of pedogenic carbonates to examine environmental variability across 5000 km 2 within the omo turkana basin an expanded isotopic dataset including the first isotopic data on pedogenic carbonates from the shungura formation and new data from the nachukui and koobi fora formations is compared to published isotopic records from both the omo turkana basin and the lower awash basin ethiopia regionally the carbon isotope record indicates a steady increase of c 4 vegetation in floodplain environments for the past 4 million years the oxygen isotopic record indicates that the isotopic composition of rainfall was depleted in 18 o relative to today s waters and that both basins likely received more rainfall in the pliocene than today a shift to higher 18 o values in paleosol carbonate after 2 ma in the omo turkana basin but not in the lower awash basin suggests that the ecology and hydrology in these two rift basins were influenced by different climatic regimes in addition to regional trends pedogenic carbonates sampled from different parts of the basin show that the distribution of c 4 vegetation and soil water 18 o values varied with proximity to the axial river system and specifically that c 3 vegetation was more dominant in soils of the shungura formation compared with coeval sediments downstream in the nachukui and koobi fora formations this large isotopic dataset from pedogenic carbonates provides the opportunity to examine how terrestrial systems responded to global climate change during the last 4 million years from both local and regional perspectives the isotopic data indicate that local basin and climate dynamics strongly influenced the impact of large scale environmental change in east african rift basins

east african lake evidence for pliocene millennial scale climate variability late cenozoic climate history in africa was punctuated by episodes of variability characterized by the appearance and disappearance of large freshwater lakes within the east african rift valley in the baringo bogoria basin a well dated sequence of diatomites and fluviolacustrine sediments documents the precessionally forced cycling of an extensive lake system between 2 70 ma and 2 55 ma one diatomite unit was studied using the oxygen isotope composition of diatom silica combined with x ray fluorescence spectrometry and taxonomic assemblage changes to explore the nature of climate variability during this interval data reveal a rapid onset and gradual decline of deepwater lake conditions which exhibit millennial scale cyclicity of 1400 1700 yr similar to late quaternary dansgaard oeschger events these cycles are thought to reflect enhanced precipitation coincident with increased monsoonal strength suggesting the existence of a teleconnection between the high latitudes and east africa during this period such climatic variability could have affected faunal and floral evolution at the time

isotopic analysis of tooth enamel carbonate from modern north american feral horses implications for paleoenvironmental reconstructions the accuracy of paleoenvironmental reconstructions based on isotope analyses of equid teeth is currently uncertain because the exact relationship between the isotope composition of modern feral equids and their environment has not been thoroughly studied we analyzed the carbon and oxygen isotope values 13c and 18o of tooth enamel carbonate and the 13c values of fecal samples from modern feral horses we compared those values with the 13c values of local vegetation and the 18o values of local waters herds were studied in two contrasting localities eastern oregon where grasslands consisted of 100 c3 species and new mexico where 95 of the grasses were c4 species carbon isotope analyses of fecal material and tooth enamel suggest that horses consumed primarily grass but some new mexico horses also consumed significant amounts of shrubs and or forbs microhistological analyses of fecal samples show that oregon horses consumed 95 grass and oregon enamel 13c values are consistent with a diet containing 100 c3 plants microhistological analyses of fecal samples from new mexico indicate a diet averaging 75 grass while enamel 13c values suggest that diets averaged 85 c4 plants range 72 97 thus reconstructions of the c3 c4 ratio of grasses in ancient grasslands that are based on the 13c values of fossil equid teeth may underestimate the abundance of c4 grasses the mean 18o values of tooth enamel paralleled the trends observed in the mean 18o values of precipitation however the mean 18o values of enamel carbonate from oregon and new mexico differed by only 3 3 which is less than the difference in the mean 18o values of precipitation 6 5 in addition the range of 18o values within new mexico enamel samples 6 5 was greater than the difference between mean enamel 18o values at each site calculated values for the 18o of water ingested by horses are 2 3 more positive than mean 18o values for corresponding precipitation suggesting that horses consumed waters that were enriched in 18o due to evaporation while our results confirm that local climatic and hydrological conditions can influence the 18o values of equid enamel they also show that the 18o values of equid teeth are not always a direct proxy for the isotope ratios of precipitation

heat transfer in magma in situ heat transfer rates in a basaltic magma were measured under typical magma chamber conditions and a numerical model of the experiment was used to estimate magma viscosity the results are of value for assessing methods of thermal energy extraction from magma bodies in the upper crust as well as for modeling the evolutionary track of these systems

a new magma chamber model based on structural studies in the oman ophiolite abstract structural mapping in the mafic ultramafic transition zone and in the overlying crustal section of the oman ophiolite has revealed the importance of magmatic flow in the formation of layering in the gabbros and the mechanical coupling between this flow and the asthenospheric flow of the underlying peridotites the crustal section near the spreading axis and in particular the magma chamber are fed by two independent melts a dominant gabbroic melt episodically injected from depth and a subordinate wehrlitic crystal mixture produced by compaction of the transition zone layering in the gabbros can be partly produced by tectonic transposition of the gabbroic and wehrlitic mixtures during magmatic flow whatever its origin the layering orientation in the newly created crust does not necessarily reflect its original attitude the final orientation of the layering is determined by the attitude of the magmatic flow plane at the time it was frozen a new magma chamber model is proposed which solves some of the physical difficulties of previous models and accounts for the seismic imaging of magma chambers beneath oceanic ridges

duality of magmatism in the plutonic sequence of the sumail nappe oman abstract detailed field mapping of the crustal sequence in several areas of the sumail ophiolite nappe mainly in the fizh the salahi and the haylayn blocks and comparisons with other well studied areas have shown that the crustal sequence was constructed by two distinct although nearly contemporaneous magmatic series the first a gabbroic series was emplaced during the accretion stage at an oceanic spreading centre which formed the layered gabbro unit the high level isotropic gabbro unit and their by products the sheeted dyke complex and the lower extrusives fine grained homogeneous planar laminated gabbros commonly occur at the top of the layered gabbro sequence in some specific areas wadi haymiliyah and wadi rajmi these are strongly differentiated fe ti rich gabbronorites and norites which coincide with large scale discontinuities within the plutonic sequence interpreted as axial discontinuities of the spreading magma chambers the second series an ultramafic wehrlitic series is locally rooted in the upper mantle i e the impregnated dunitic transition zone this has intruded the whole crustal sequence up to the pillow lavas countless discordant and concordant wehrlitic bodies intruded the plutonic sequence making up 20 40 of it in volume we describe the various settings and forms of these intrusions which were largely underestimated in previous studies we also describe their mineralogy and textures and show with chemical and mineralogical arguments that these bodies evolved as relatively closed systems independently from each other we infer from the study of the contacts that the gabbros were still hot and consolidated just at the moment of the wehrlitic intrusion at the base of the crust however indications of immiscibility between gabbros and wehrlites are common suggesting that both magmatic series were quite contemporaneous the wehrlites are commonly isotropic and may exhibit an internal layering of the dunite wehrlite clinopyroxenite type sometimes appearing at the upper or lower margins of the intrusions in this case the ultramafic layered cumulates show lobate intrusive contacts with the adjacent layered gabbros these plagioclase free ultramafic layered cumulates therefore are not interbedded within the gabbro cumulates but actually belong to the wehrlitic intrusive series picritic dykes radiating from the uppermost intrusions can be traced up to the upper extrusives which are for the main part cogenetic with the wehrlites the time of this second magmatic event coincides with the cessation of the accretion process and with the beginning of the intraoceanic detachment of the ophiolite at the spreading centre we believe that the compressive regime that initiated the detachment acted as an efficient filter press and helped the extraction and ascent of the wehrlitic magmas towards the uppermost levels of the crust

stable isotope analyses of tooth enamel carbonate of large herbivores from the tugen hills deposits palaeoenvironmental context of the earliest kenyan hominids abstract understanding shifts in past climatic and environmental conditions are crucial for throwing light on human evolution available reconstructions of the palaeoecology of faunal and floral assemblages indicate that the earliest kenyan hominids including orrorin tugenensis are associated with forest landscapes in this study we present stable isotope data of tooth enamel carbonate of large herbivores associated with these hominids in order further to evaluate their environmental context fossil teeth were sampled in the lukeino formation 6 1 5 7 ma late miocene and the mabaget formation 5 3 4 5 ma early pliocene at the foot of the tugen hills great rift valley despite chemical changes in fossil enamel preservation of the palaeoenvironmental signals is supported by the difference in 18 o between hippos and terrestrial fauna moreover the giraffid specimen from the mabaget formation exhibits one of the highest 18 o values as expected for a drought tolerant animal the 13 c of large herbivores indicates that the earliest kenyan hominids inhabited a mixed c 3 c 4 environment as did ardipithecus ethiopia and sahelanthropus chad two early putative hominids the tugen hills might have been a wooded grassland with patches of woodland there is no record of closed canopy forest at the time of deposition we emphasize differences in food habits among herbivore groups deinotheres nearly all elephantids and the giraffid individual had a c 3 diet which reflected browsing behaviour the intake of c 4 plants prevailed for equids and gomphotheres and was consistent with grazing habits most hippos and suids were mixed c 3 c 4 feeders and consequently were generalist herbivores bovids and rhinos had a diet ranging from c 3 to c 4 plants variations in 13 c and 18 o among faunal assemblages suggest changes in local climate and vegetation moister conditions likely occurred in the early pliocene and the latest miocene ca 5 7 ma than before the c 3 plant biomass would have increased in the latest miocene there were probably denser stands of trees within the depositional environment during the early pliocene than in the late miocene which is consistent with palaeontological studies

gorongosa by the sea first miocene fossil sites from the urema rift central mozambique and their coastal paleoenvironmental and paleoecological contexts abstract the east african rift system ears has played a central role in our understanding of human origins and vertebrate evolution in the late cenozoic of africa however the distribution of fossil sites along the rift is highly biased towards its northern extent and the types of paleoenvironments are primarily restricted to fluvial and lacustrine settings here we report the discovery of the first fossil sites from the urema rift at gorongosa national park central mozambique at the southern end of the ears and reconstruct environmental contexts of the fossils in situ and surface fossils from the lower member of the mazamba formation estimated to be of miocene age comprise mammals reptiles fishes invertebrates palms and dicot trees fossil and geological evidence indicates a coastal plain paleoenvironmental mosaic of riverine forest woodland and estuarine habitats that represent the first coastal biomes identified in the neogene ears context receiving continental sediment from source terranes west of today s urema graben estuarine sequences accumulated prior to rifting as compound incised valley fills on a low gradient coastal plain following transgression modern environmental analogues are extremely productive habitats for marine and terrestrial fauna including primates thus our discoveries raise the possibility that the miocene coastal landscapes of gorongosa were ecologically favorable habitats for primates providing relatively stable maritime climate and ecosystem conditions year round freshwater availability and food both from terrestrial and marine sources the emerging fossil record from gorongosa is beginning to fill an important gap in the paleobiogeography of africa as no fossil sites of neogene age have previously been reported from the southernmost part of the ears furthermore this unique window into past continental margin ecosystems of central mozambique may allow us to test key paleobiogeographic hypotheses during critical periods of primate evolution

importance of the indian ocean for simulating rainfall anomalies over eastern and southern africa the relative contributions of the indian ocean and pacific ocean sea surface temperatures ssts to the rainfall variability over eastern central and southern africa during the austral spring summer are examined the variability of african rainfall is statistically related to both oceans but the variability in the two oceans is also related to separate the effects of the indian and pacific oceans a suite of numerical model simulations is presented goga the atmosphere is forced by observed ssts globally ioga the atmosphere is forced by observed ssts only in the indian ocean basin and poga the atmosphere is forced by observed ssts only in the tropical pacific basin while the sst variability of the tropical pacific exerts some influence over the african region it is the atmospheric response to the indian ocean variability that is essential for simulating the correct rainfall response over eastern central and southern africa analyses of the dynamical response s seen in the numerical experiments and in the observations indicate that the pacific and indian oceans have a competing influence over the indian ocean african region this competition is related to the influence of the two oceans on the walker circulation and the consequences of that variability on low level fluxes of moisture over central and southern africa finally given the high correlation found between sst variability in the indian and pacific oceans with the pacific leading by 3 months we speculate on an approach to long lead dynamical climate prediction over central east and southern africa

stable isotope variation in tooth enamel from neogene hippopotamids monitor of meso and global climate and rift dynamics on the albertine rift uganda the neogene was a period of long term global cooling and increasing climatic variability variations in african asian monsoon intensity over the last 7 ma have been deduced from patterns of eolian dust export into the indian ocean and mediterranean sea as well as from lake level records in the east african rift system ears however lake systems not only depend on rainfall patterns but also on the size and physiography of river catchment areas this study is based on stable isotope proxy data 18o 16o 13c 12c from tooth enamel of hippopotamids mammalia and aims in unravelling long term climate and watershed dynamics that control the evolution of palaeolake systems in the western branch of the ears lake albert uganda during the late neogene 7 5 ma to recent having no dietary preferences with respect to wooded c3 versus grassland c4 vegetation these territorial water dependant mammals are particularly useful for palaeoclimate analyses as inhabitants of lakes and rivers hippopotamid tooth enamel isotope data document mesoclimates of topographic depressions such as the rift valleys and therefore changes in relative valley depth instead of exclusively global climate changes consequently we ascribe a synchronous maximum in 18o 16o and 13c 12c composition of hippopotamid enamel centred around 1 5 2 5 ma to maximum aridity and or maximum hydrological isolation of the rift floor from rift external river catchment areas in response to the combined effects of rift shoulder uplift and subsidence of the rift valley floor structural rearrangements by 2 5 ma within the northern segment of the albertine rift are well constrained by reversals in river flow cannibalisation of catchments biogeographic turnover and uplift of the rwenzori horst however a growing rain shadow is not obvious in 18o 16o signatures of the hippopotamid teeth of the albertine rift according to our interpretation this is the result of the overriding effect of evaporation on 18o 16o responding to aridification of the basin floor by a valley air circulation system through relative deepening of the valley on the other hand a synchronous arid pulse is not so clearly recorded in palaeosol data and mammalian fauna of the eastern branch of the ears this discrepancy indicates that rift mesoclimates may represent an underestimated aspect in previous palaeoclimate reconstructions from rift valley data and represent a clear limitation to attempts at global climate reconstructions the results of this study also suggest that using 18o 16o data as a proxy to rain shadow evolution must take into account relative basin subsidence to properly document mountain range uplift

use of carbon isotopes in paleosols as an indicator of the p co2 of the paleoatmosphere measurements of carbon isotopic composition of coexisting paleosol organic matter and carbonate results in improved estimates of the paleo p co2 content of the paleoatmosphere measurements from tertiary paleosols indicate that the levels of co2 in the early eocene middle and late miocene and pliocene were less than 1000 ppmv early cretaceous levels of p co2 were significantly higher of the order of 1500 to 3000 ppmv

segmentation at a fossil spreading axis the plutonic sequence of the wadi haymiliyah area haylayn block sumail nappe oman abstract wadi haymiliyah in the central part of the haylayn block offers a splendid continuous section across the crustal sequence of the sumail ophiolite the plutonic sequence of this area presents several specific features of great interest for the understanding of the structure and evolution of this ophiolite the petrological moho and the whole plutonic sequence display a subvertical attitude parallel to the mean dyke complex orientation high temperature folding occurred in the mantle sequence and in the lower crust whereas the upper crust remained unfolded and behaved as a rigid slab during this deformation resulting in a tectonic decoupling between lower and upper crust in the gabbro cumulate sequence a remarkable large scale curvature of the magmatic structures layering and lamination planes whose axis is totally discordant with the regional folds axes is interpreted as a primary magmatic feature indicating the southern ending of a magma chamber the lower crust about 2 km thick consists of a primary layered gabbroic sequence consisting of rhythmic mineral graded layers from several metres to several hundred metres thick syndepositional structures such as oblique stratification microslumps eroding mini channels and small normal faults are widespread the mineralogical composition modal variations and cryptic evolution of the whole layered sequence are described both at the megascale and on the simple cyclic scale the data support a model of crystallization of the layered sequence by open system fractionation at the floor and sides of a periodically replenished steady state magma chamber a unique feature of this cumulate sequence is the ubiquitous presence of orthopyroxene throughout the whole cumulate pile this is very unusual in the sumail crust with the exception of the wadi rajmi section in the fizh block two huge plagioclase free dunite wehrlite laccoliths about 300 m thick and numerous ultramafic sills and mushroom like bodies intrude the base of the layered sequence these ultramafic intrusions exhibit in places an internal layering and dunitic differentiation products they have sharp sinuous and lobate contacts with the gabbros which were still hot and probably not entirely consolidated at the moment of the intrusion the mineral compositions of these intrusions are much more primitive than those of the adjacent gabbros higher in the plutonic section the layered gabbros are overlain by 1 km of fine grained non layered planar laminated gabbronorites characterized by the abundance of pleochroic cumulus hypersthene the disappearance of olivine and the development of fe ti oxides and amphibole as post cumulus phases numerous occurrences of concordant coarse grained layered gabbros occur in this unit which is characterized also by a dense net of highly residual dioritic to tonalitic veins resulting in a huge magmatic breccia in the uppermost few hundred metres where the gabbronorites are brecciated by the acidic rocks hydrothermal veins are also extremely abundant in this unit which coincides with the core of the large scale curvature this unit comprising unusually fractionated rocks is interpreted as resulting from the evolution of the haymiliyah magma chamber towards a closed system fractionation due to the cutting off of source supply our interpretation of both structural and petrological data may be summarized by the following major points 1 1 the haymailiyah magma chamber was located at the southern tip of a spreading cell and was cut off from the magma supply at the end of its evolution either vertically when accretion slowed down or horizontally when it became isolated from the central part of the spreading segment we suggest that orthopyroxene bearing cumulates should be looked for all along the sumail nappe and used as markers of segmentation 2 2 early high temperature compressional deformation took place in both the mantle and crust before the intraoceanic detachment of the ophiolite the development of this compression regime activated filter pressing processes and in particular helped with the extraction of wehrlitic magmas from the upper mantle and their ascent to the uppermost levels of the crust

the formation of plagioclase chains during convective transfer in basaltic magma the basaltic rock in the lower part of the thick holyoke lava flow in connecticut and massachusetts has been shown to have a remarkable texture with crystals of feldspar linked together in a continuous three dimensional network of chains1 heating experiments have revealed that this network persists to temperatures where the rock is 75 liquid2 and therefore the network was interpreted to have formed at an early stage of crystallization and to have played an important role in the compaction of crystal mush in the lower part of the flow3 4 despite the texture s importance to our understanding of how such basalt flows form the origin of the texture has remained uncertain1 2 3 here we show that although the network is present in the lower third of the flow it was actually formed in the upper solidification front and was transported down in plumes of dense crystal mush convection of this type has been postulated for intrusive magma chambers but corroborative field evidence has been equivocal especially in lava lakes and flows preservation of the roof generated texture in the lower part of a thick flood basalt flow therefore constitutes important evidence for the role of convection in the solidification and differentiation of a simple magma sheet

three dimensional p velocity structure of the crust below newberry volcano oregon utilizing teleseismic p residuals we have detected a column of high p velocity material extending from within 10 km of the surface below the summit of newberry volcano oregon to midcrustal depths near 25 km we interpret this column to be the expression of a swarm of predominantly subsolidus gabbroic sills and dikes which were intruded as the volcano was built the high p velocities observed below the volcano severely limit the size of magma chambers which could presently exist in the crust below newberry volcano those possible include a few percent of partial melt distributed through large volumes of a mafic intrusion zone in the midcrust a few smaller higher melt fraction zones in the midcrust with dimensions less than 6 km and whose aggregate volume is only a few percent of enclosing volumes of 200 km sup 3 small magma bodies with dimensions of a few kilometers located within the upper 10 km of the crust or a mafic crystal rich magma of arbitrary dimensions located in the upper few km the low p velocities detected in the upper 4 km beneath the center of the summit caldera may be partially caused by a magma chamber in the second ofmore these catagories less

isotopic evidence for plio pleistocene environmental change at gona ethiopia abstract a 4 5 ma record of fluvial and lacustrine deposits is well exposed at gona in the afar depression of ethiopia we use isotopic values of pedogenic carbonate and fossil teeth to reconstruct plio pleistocene environmental change at gona an increase in 13c values of pedogenic carbonates since 4 5 ma points to a shift from woodlands to grassy woodlands in the early pliocene 10 4 to 3 9 vpdb to more open but still mixed environments in the late pleistocene 3 0 to 1 4 vpdb this pattern is also seen in isotopic records elsewhere in east africa however at 1 5 ma the higher proportion of c4 grasses at gona is largely a result of a local facies shift to more water limited environments the wide range of 13c values of pedogenic carbonate within single stratigraphic levels indicates a mosaic of vegetation for all time intervals at gona that depends on depositional environment elements of this mosaic are reflected in 13c values of both modern plants and soil organic matter and plio pleistocene soil carbonate indicating higher amounts of c4 grasses with greater distance from a river channel in both the modern and ancient awash river systems 18o values of pedogenic carbonates increase up section from 11 9 in the early pliocene to 6 4 vpdb in the late pleistocene the wide range of 18o values in paleovertisol carbonates from all stratigraphic levels probably reflects short term climate changes and periods of strong evaporation throughout the record based on the comparison between 18o values of plio pleistocene pedogenic carbonates and modern waters we estimate that there has been a 6 5 increase in mean annual 18o values of meteoric water since 4 5 ma 18o values of pedogenic carbonate from other east african records indicate a similar shift increasing aridity and fluctuations in the timing and source of rainfall are likely responsible for the changes in 18o values of east african pedogenic carbonates through the plio pleistocene

construction of the oceanic lithosphere by magmatic intrusions petrological evidence from plutonic rocks formed along the fast spreading east pacific rise we report textural and compositional characteristics of plutonic rocks found in four sites exposed 5000 m below sea level along the southern east pacific rise system studied outcrops of plutonic rocks are located along escarpments in two transform faults garrett and terevaka and in two deep regions exposed by the action of propagating rifts pito deep and hess deep the transform faults have a large variety of heterogeneous plutonic rocks with mineral compositional trends extending from relatively primitive values in the olivine bearing gabbros to very fractionated values in the ferrogabbros an abundance of ferrogabbros in these transform faults suggests small and ephemeral magma chambers in which liquid and crystal mush evolved by crystal fractionation in small pockets and intrusive sills conversely pito deep and hess deep have mainly homogeneous cumulates without the fractionated end members instead mineral compositions range to highly primitive values the ubiquity of homogeneous olivine bearing gabbros at pito deep and hess deep suggests a more robust magma chamber with frequent injection and mixing involving larger volumes of crystal liquid mush which buffers compositions we infer that the lithosphere created near ridge transform intersections of fast spreading centers is controlled by a colder mantle regime and will be lithologically and compositionally different from lithosphere created near hotter segment centers and away from such discontinuities our observations show that magmatic intrusion is a fundamental process in the construction of the lower oceanic crust

heat transfer measurements of the 1983 kilauea lava flow convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of kilauea volcano in hawaii eight field measurements of induced natural convection were made giving heat flux values that ranged from 1 78 to 8 09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees celsius respectively these field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace melted samples of molten lava and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy

growth rates of pedogenic carbonate coatings on coarse clasts abstract growth rates of pedogenic carbonate coatings on clasts can be used as a simple quantitative index of soil and sediment age as well as a chronological framework for palaeoecological reconstructions they are also probably connected with general intensity of formation of bk horizons in soils previously data on coating growth rates were restricted ecologically and geographically to desert regions of north america this paper presents growth rates of holocene pedogenic carbonate coatings on clasts within an extended range of environments calculated on the basis of archaeological and radiocarbon dating the rates in this study are higher than in earlier reports carbonate coatings can thicken with rates up to 1 mm 1000 years or higher in semi arid and semi humid climates at least five factors are likely to control growth rates 1 climate 2 lithology of carbonate parent material 3 depth under the soil surface 4 clast size 5 bulk density and composition of cutans favorable factors for comparatively rapid coating thickening seems to be climatic conditions ranging from semi arid to semi humid high carbonate content of parent material and large size of clasts there is also an optimal depth of carbonate coating growth in a soil profile little information on bulk density and composition of cutans is available but they appear to play an important role as one of the factors governing growth rates of pedogenic carbonate coatings on clasts

dendrogeomorphic assessment and sediment transfer of natural vs mining induced debris flow activity in călimani mountains eastern carpathians romania abstract during the second half of the twentieth century in the central part of the c limani mountains the mining activities for sulfur rich ore extraction and processing produced significant landscape changes sediment transfers across the affected catchments started during the mining period and are still ongoing today more than two decades after the cessation of the mining activities in 1997 subsequently neither rehabilitation works nor erosion control measures were undertaken to stabilize the spoil heap deposits and natural reforestation also material consolidation was impeded by the highly unstable talus slopes moreover little is known about the frequency of the hydrogeomorphic processes responsible for sediment transfers and their consequences dendrogeomorphic investigations grain size analyses and topographic surveys were carried out to document the history of hydrogeomorphic activity the volume of material stored behind the retention dams and the rate of sediment accumulation tree ring analysis allowed us to reconstruct ten debris flow events in the natural environment as well as in mining disturbed environment for the period 1931 2017 and 1970 2017 respectively triggering of debris flows appears related to spring and summer precipitation originating from short duration convective systems or long lasting rainfalls in these remote mining areas the reconstructed frequency of debris flows return intervals of 8 1 and 4 7 years might be explained by the rainwater accumulation on the spoil heap platform and the availability of sediments which flow down the talus and then follow the stream channels to reach one of the sediment retention reservoirs 7 4 8 4 cm y 1

discerning crystal growth from diffusion profiles in zoned olivine by in situ mg fe isotopic analyses mineral zoning is used in diffusion based geospeedometry to determine magmatic timescales progress in this field has been hampered by the challenge to discern mineral zoning produced by diffusion from concentration gradients inherited from crystal growth a zoned olivine phenocryst from kilauea iki lava lake hawaii was selected for this study to evaluate the potential of mg and fe isotopes for distinguishing these two processes microdrilling of the phenocryst 300 m drill holes followed by mc icpms analysis of the powders revealed negatively coupled mg and fe isotopic fractionations 26mg from 0 1 to 0 2 and 56fe from 1 2 to 0 2 from core to rim which can only be explained by mg fe exchange between melt and olivine the data can be explained with ratios of diffusivities of mg and fe isotopes in olivine scaling as d2 d1 m1 m2 with mg 0 16 and fe 0 27 la mc icpms and mc sims fe isotopic measurements are developed and are demonstrated to yield accurate 56fe measurements within precisions of 0 2 1 sd at spatial resolutions of 50 m 56fe and 26mg stay constant with fo in the rim late stage overgrowth whereas in the core original phenocryst 56fe steeply trends toward lighter compositions and 26mg trends toward heavier compositions with higher fo a plot of 56fe vs fo immediately distinguishes growth controlled from diffusion controlled zoning in these two regions the results are consistent with the idea that large isotopic fractionation accompanies chemical diffusion in crystals whereas fractional crystallization induces little or no isotopic fractionation the cooling timescale inferred from the chemical isotope zoning profiles is consistent with the documented cooling history of the lava lake in the absence of geologic context in situ stable isotopic measurements may now be used to interpret the nature of mineral zoning stable isotope measurements by la mc icpms and mc sims can be used as standard petrologic tools to identify samples for diffusion based geospeedometry

magmatic processes under mid ocean ridges a detailed mineralogic study of lavas from east pacific rise 9 30 n 10 30 n and 11 20 n 1 detailed petrologic study has been made for lavas from the northern east pacific rise epr 9 30 n 11 20 n and 10 30 n 9 30 n and 11 20 n have robust magma supply and a shallow melt lens while 10 30 n has nonrobust magma supply and no shallow melt lens lavas from all three localities are sparsely phyric and glassy containing plagioclase olivine pyroxene typically the lavas contain several to many up to seven distinct chemical groups of plagioclase that are not always distinct texturally the lavas may also contain up to three chemically distinct groups of olivine and two groups of pyroxene the lavas contain both individual crystals and groups comprising reticulate and dendritic clots that we interpret to represent bits of crystal networks forming in mushy zones of an axial magma chamber 21 of the 23 samples studied in detail have diverse crystal compositions and require mixing which most likely occurs when mostly liquid magma passes through mushy zones we find no significant systematic differences between robust and nonrobust segments in terms of their crystal content proportion of texturally distinct xenocrysts crystal size aspect ratio roundness modal abundance magma residence time number of diverse mineral chemical groups and characteristics of mixing like the total range of composition of disequilibrium minerals present and the magnitude of the chemical gaps between disequilibrium and equilibrium compositions this unexpected and remarkable similarity suggests that the presence or absence of a seismically imaged shallow melt lens has essentially no effect on the mineralogy of erupted lavas we conclude that the fundamentally important magmatic process under mid ocean ridges from slow to fast is the formation of crystal networks and their subsequent compaction the seismically detected shallow melt lenses likely contain highly evolved magma formed by expelled interstitial melt during crystal network compaction and play very little role in crustal accretion our conclusion implies that the thick 3 km low velocity zone near the base of the crust produces the thin 30 m shallow melt lenses not the other way around

downhole periodic seismic sources downhole periodic seismic sources have been proposed as a means for studying fluid zones in hydrothermal magma systems encountered in deep scientific holes drilled as part of the continental scientific drilling program scientific measurements in these holes will require the use of downhole nondestructive high resolution seismic tools downhole periodic seismic sources tested in a shallow geothermal zone showed that a pneumatic oscillator could effectively generate downhole low frequency 10 100 hz seismic waves and that these waves could effectively penetrate a highly fractured formation an improved version of these downhole sources capable of swept frequency operation is currently under development this type of downhole seismic source has applications in crustal studies and in the evaluation of petroleum groundwater and geothermal reservoirs

stable isotope dietary reconstructions of herbivore enamel reveal heterogeneous savanna ecosystems in the plio pleistocene malawi rift abstract the plio pleistocene expansion of eastern africa savanna ecosystems was a major driver for morphological and behavioral innovations in hominin evolution most evidence for hominin ecosystem reconstructions originates from the eastern rift in today s somali masai endemic zone we provide stable carbon 13 c and oxygen 18 o isotope data from 22 bovid equid suid hippopotamid and elephant teeth from the southern part of the east african rift and supplement these by 18 o values of present day meteoric water this region karonga basin malawi hosts remains of homo rudolfensis and paranthropus boisei it is situated between hominin bearing sites in eastern and southern africa and therefore fills an important geographical gap for hominin evolution tooth enamel 13 c and 18 o data of 14 large bodied mammalian herbivore species from units 2 and 3 ca 4 3 to 0 6 ma in the chiwondo beds provide information about foraging strategies and vegetation patterns our stable isotope data reflect c 3 dominated ecosystems that permitted access to open c 4 environments for migratory mammals many analyzed taxa show evidence for mixed diets with high abundances of c 3 biomass consumption only selected bovids were specialized grazers 18 o of present day meteoric water reflects rainfall amount and seasonality elevation and lake evaporation 18 o values of karonga basin herbivore enamel are generally low and cover values similar to present day drinking water indicating both evaporated and freshwater sources comparison of 13 c values from the karonga basin with other eastern african herbivore communities reveals significant differences in dietary patterns with much more generalized mixed c 3 c 4 and pure c 3 feeding behaviors in the malawi rift similarly enamel 18 o values are lower than in most plio pleistocene eastern african herbivores suggesting more humid conditions collectively our data support models in which early hominin foraging activity included access to c 3 dominated biomes complicating traditional interpretations linking early human evolutionary innovations to a shift towards savanna habitats

paleoseasonality inferred from equid teeth and intra tooth isotopic variability abstract this research presents a study of intra tooth isotopic variability measured in hypsodont equid teeth as a means of determining paleoseasonality the purpose of this investigation is to determine whether sivapithecus a miocene hominoid from the siwaliks of pakistan lived in habitats characterized by a seasonal rainfall regime and if so what kind of forest is associated with this regime forest type such as evergreen semi evergreen moist deciduous and dry deciduous is largely determined by length of the dry period reconstruction of the rainfall regime therefore allows inferences of forest type in the fossil record seasonal rainfall regimes can be determined from oxygen stable isotopes for oxygen isotopes track amount of rainfall in tropical regions sampling oxygen isotopes along the length of an equid tooth which takes over a year to develop therefore provides a record of seasonal isotopic changes in body water which in turn reflect drinking water and ultimately precipitation carbonate oxygen results from siwalik equid teeth spanning 10 0 6 3 ma indicate a rainfall regime similar to that experienced by southern china monsoon forests today with a monsoonal rainy season and a five to six month dry season furthermore results suggest a seasonal birthing pattern for siwalik equids and therefore predictable seasonal regime these results indicate that sivapithecus lived under a seasonal regime with dry periods longer than the maximum of 4 months that most great apes experience today therefore sivapithecus may have experienced longer periods of low fruit availability than do modern apes either sivapithecus differed in habitat requirements or the forest differed in terms of the spatio temporal variability of fruit compared to modern analogues over geologic time annual rainfall appears to have decreased in the siwaliks beginning around the time sivapithecus became extinct but annual seasonality of rainfall does not change

oxygen isotope variations in phosphate of biogenic apatites iv mammal teeth and bones groups of rats grown from birth to death in identical conditions but with different 18o of drinking water w were studied for variations of 18o of their body water bw and bone phosphate p there is a high linear correlation r 0 99 between bw and between p and w the regression lines have similar slope coefficients 0 53 and 0 49 values of p of different teeth and bones are the same within the precision of the method 0 5 the isotopic fractionation coefficient between phosphate and body water is 1 0178 and close to the estimated value of 1 0173 derived from the phosphate paleotemperature equation deviations from constant fractionation between bone phosphate and environmental drinking water depend primarily on rates of drinking and metabolism environment conditions have relatively little effect on oxygen isotope fractionation between water sources and bone phosphate

magma flow and interaction with waste packages in a geologic repository at yucca mountain nevada abstract the likelihood that a nuclear waste repository at yucca mountain could be intersected by igneous activity is very low but its potential consequences are nevertheless important to performance assessments an ongoing critical area of concern is the nature and magnitude of the thermal interaction of magma with tunnel walls high level nuclear waste packages and waste forms previous assessments consider a variety of dynamic scenarios but large uncertainties remain in understanding the rheological nature of the magma likely to be involved and its behavior within a repository drift here we specifically address the issue of magma rheology during degassing cooling and solidification as basaltic magma approaches earth s surface and enters a drift magma containing significant amounts 2 wt of dissolved water wet magma as is anticipated for this region at or near its liquidus temperature and saturated with water at 200 mpa is at a temperature near or below the 1 atm solidus temperature isentropic ascent from this near liquidus temperature promotes extensive solidification and or glassification exsolving water with approach to the surface promotes rapid vesiculation leading to fragmentation and tephra production with continued ascent the still water saturated magma traverses the solidification phase field and undergoes a combination of rapid crystallization and quenching becoming a glassy highly viscous 108 pa s mass of greatly reduced mobility this immobility is reflected in the high effective viscosity regulating flows from nearby cinder cones associated with wet basalt this also matches well with the experimentally determined rheology of dry basalt glass this rheology greatly restricts the mobility of basalt within repository drifts amounting to

nondestructive downhole seismic vibrator source and processes of utilizing the vibrator to obtain information about geologic formations a nondestructive downhole seismic source 10 capable of generating sv waves sh waves and p waves alone or in combination to determine information about a surrounding geologic formation the invention also includes processes of performing crosswell tomography and reverse vertical seismic profiling the invention also includes a means 60 and process to carry out in hole seismic logging operations

oxygen isotope analyses of co existing carbonate and phosphate in biogenic apatite a way to monitor diagenetic alteration of bone phosphate abstract the oxygen isotopic composition of phosphate 18 op and structural carbonate 18 oc of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries these two variables are highly correlate r 2 0 98 and the calculated best fit of linear regression is very similar to the equation calculated from the phosphate and carbonate palaeotemperature equations 1 2 according to previous measurements 3 6 on fossils of different ages from different areas it seems quite improbable to find isotopically altered skeletal remains showing a good correlation between 18 op and 18 oc as is the case with modern samples it therefore seems possible at least in some cases to use these measurements for monitoring fossil bone and tooth diagenetic alteration when a set of points lie on the equilibrium line or close to it the 18 o values could be considered close to the original values in contrast when the points lie to the left or to the right of this line this probably means that the values are diagenetically modified due to interaction with meteoric water or 18 o enriched water respectively

convective heat extraction from molten magma the convective heat of molten magma in the upper 10 km of the continental crust represents a significant geothermal energy resource shallow basaltic magmas 10 km near the liquidus 1250 c are predicted to offer heat extraction rates in the range of 15 50 kw m2 20 80 mw well more accessible andesitic and wet rhyolitic magmas are predicted to offer heat extraction rates in the range of 5 25 kw m2 8 40 mw well convective heat transfer correlations are used which include corrections for high prandtl number fluids and cylindrical boundary layers the calculations based on these correlations agree well with laboratory tests using molten basalt at superliquidus temperatures 1450 1650 c at liquidus and subliquidus temperatures an additional correction is developed for the thick solidified crust that forms on the heat exchanger non newtonian rheology is considered and shown to have a possible effect on the initiation of convection in the liquidus and subliquidus temperature range in addition to heat extraction estimates the analysis presented here is also relevant to convective heat loss to walls of magma bodies

the impact of topography on isotopes in precipitation across the central anatolian plateau turkey paleoelevation reconstructions of mountain belts and orogenic plateaus based on stable isotope climate and precipitation records benefit greatly from present day calibrations that relate the fractionation of hydrogen d and oxygen 18o isotopes in precipitation to orographic rainfall here we establish a first order template of d and 18o of modern meteoric waters across the central anatolian plateau cap and its bordering pontic and taurus mountains we identify key regions in the plateau interior and along the plateau margins that have the potential to reliably record topography related paleotemperature and paleoprecipitation changes as recovered from stable isotope paleosol fossil teeth or lipid proxy data based on d and 18o data of more than 480 surface water samples from small catchments and springs we characterize moisture sources affecting the net isotopic budget of precipitation over the cap and analyze how orographic rainout and plateau aridity shape modern patterns of d and 18o in precipitation the taurus mountains bordering the cap to the south act as a major orographic barrier for transport of predominantly winter moisture and exhibit isotopic lapse rates of approximately 20 km for d and 2 9 km for 18o across an elevation range of nearly 3000 m the pontic mountains at the northern margin of the cap force perennial moisture to ascend and condensate revealing lapse rates of 19 km for d and 2 6 km for 18o the difference in the predominant moisture source for the southern and northern margins of the cap north african versus atlantic air masses is manifested in systematic north south differences in near sea level meteoric water compositions of dn s 20 permil and 18on s 3 permil in a swath across the central part of the plateau stable isotope data from the semi arid plateau interior with rainfall as low as 300 to 500 mm yr and mean summer temperatures attaining 23 c provide clear evidence for an evaporative regime that drastically affects surface water and runoff compositions and results in a local meteoric water line for the plateau interior that follows d 4 0 18o 29 3 strongly evaporitic conditions contrast rainfall patterns along the plateau margins including their immediate leeward flanks where d and 18o elevation relationships are reliable predictors of modern topography

the magma body at kilauea iki lava lake potential insights into mid ocean ridge magma chambers although geological and geophysical measurements at active ridges have provided indirect samples and remote images and ophiolites have provided fossil evidence the lack of direct sampling of in situ physical and chemical properties severly hinders our understanding of subsurface magmatic systems at mid ocean ridges in contrast with the ridge setting substantial information has been gained from direct sampling of kilauea iki lava lake we reanalyze time series physical and petrological data from both in situ sampling and remote seismic and electromagnetic imaging of this lava lake in order to gain insights into the evolution of an enclosed basaltic magma body with many characteristics similar to a mid ocean ridge magma chamber although the analogy is imperfect our analysis of observations from kilauea iki suggests that at a mid ocean ridge 1 a fine structure exists at the top of the magma body in the form of horizontal segregation veins i e sills 2 sustained convection within the magma chamber is highly unlikely 3 a dry out zone above the magma body and below the deepest penetration of hydrothermal circulation may exist 4 with high magma supply e g the east pacific rise where quasi steady state melt zones are present the magma chamber must be completely replenished very frequently at least every 300 600 years and 5 the onset of rigid behavior of the basaltic partial melt does not happen at a unique critical crystal fraction these results also show that significant differences may occur in interpretation of the rheology of a magmatic system depending upon the type of petrologic seismic or drilling data analyzed

convective transport in crustal magma bodies abstract convective transport in enclosures is reviewed as it relates to magma bodies convective effects are discussed that are peculiar to the rheological character of magma the large prandtl number of magma delays onset of turbulence and causes velocity disturbances to extend far beyond the thermal boundary layer and well into the fluid core a boundary layer analysis is used to show that convective transport in enclosed magma bodies produces an upward heat flux which can lead to migration of magma by upmelting multicellular convection is discussed and shown to produce upflow at the walls in cases where extensive cooling occurs at the top of the magma chamber multicellular convection can lead to bimodal magma systems and can also produce vertical zonation and layering examples of oscillatory convective circulation are given and this phenomena is discussed as a possible mechanism for eruptive cycles and for vertical zonation in magma chambers non newtonian rheology is also examined as it applies to convection in magma

an isotopic study of paleosol carbonates from olduvai gorge the isotopic composition of paleosol carbonates from olduvai gorge can be used to give estimates of the paleoclimatic history of east africa during the plio pleistocene oxygen isotopes are indicative of major changes in the isotopic composition of meteoric water while carbon isotopes are indicative of major changes in the fraction of biomass using the hatch slack c4 photosynthetic pathway three major periods of climatic change in this terrestrial setting occurred at about 1 67 1 3 and 0 6 myr these involved major changes in flora as well as major changes in the isotopic composition of meteoric water overall the climate has become warmer and more arid over the past 2 2 myr

isotopic records of climate seasonality in equid teeth abstract we investigate how oxygen isotopes in equid teeth can be used as a record of seasonality first we use in situ laser ablation and conventional microsampling techniques to understand time averaging of environmental signals in intra tooth isotope profiles in modern feral horse teeth n 5 from mongolia where there is a large seasonal gradient in the oxygen isotopic composition of precipitation we demonstrate that laser ablation can be used to sample inner middle and outer enamel layers in large mammalian herbivore teeth the inner enamel layer records less attenuated isotopic signals than other layers as predicted by the mineralization patterns but intra tooth signal amplitude is similar for laser and conventional sampling methods second we use modern zebra teeth n 21 collected in eastern africa to evaluate how intra tooth oxygen isotope variation relates to rainfall patterns in the tropics we show that the intra tooth isotopic range increases with intra annual precipitation isotopic range which in turn relates to aridity in the equatorial bimodal rainfall region but is influenced by other hydroclimate processes in the region as a whole finally we address isotopic seasonality during the early pleistocene in eastern africa using oxygen isotopes in fossil equid teeth from southwestern kenya n 11 and northern tanzania n 5 we find variable isotopic seasonality in the past similar to present day eastern africa consistent with the notion that hominins and other mammals were able to accommodate environmental variability on intra annual scales in addition to well documented orbital cycles

determinants of blood water δ18o variation in a population of experimental sheep implications for paleoclimate reconstruction abstract mammalian body blood and hard tissue oxygen isotope compositions 18o values reflect environmental water and food sources climate and physiological processes for this reason fossil and archaeological hard tissues which originally formed in equilibrium with body chemistry are a valuable record of past climate landscape paleoecology and animal physiology and behavior however the environmental and physiological determinants of blood oxygen isotope composition have not been determined experimentally from large herbivores this class of fauna is abundant in cenozoic terrestrial fossil assemblages and the isotopic composition of large herbivore teeth has been central to a number of climate and ecological reconstructions furthermore existing models predict blood water or nearly equivalently body water 18o values based on environmental water sources these have been evaluated on gross timescales but have not been employed to track seasonal variation here we report how water food and physiology determine blood water 18o values in experimental sheep ovis aries subjected to controlled water switches we find that blood water 18o values rapidly reach steady state with environmental drinking water and reflect transient events including weaning seasons and snowstorms behavioral and physiological variation within a single genetically homogenous population of herbivores results in significant inter animal variation in blood water 18o values at single collection times 1 s d 0 1 1 4 range 3 5 and reveals a range of water flux rates t1 2 2 2 2 9 days within the population we find that extant models can predict average observed sheep blood 18o values with striking fidelity but predict a pattern of seasonal variation exactly opposite of that observed in our population for which water input variation was controlled and the effect of physiology was more directly observed we introduce to these models an evaporative loss term that is a function of environmental temperatures the inclusion of this function produces model predictions that mimic the observed seasonal fluctuations and match observations to within 1 0 these results increase the applicability of available physiological models for paleoseasonality reconstructions from stable isotope measurements in fossil or archaeological enamel the composition of which is determined in equilibrium with blood values however significant blood 18o variation in this experimentally controlled population should promote caution when interpreting isotopic variation in the archaeological and paleontological record

cumulate gabbros from the southwest indian ridge 54 s 7 16 e implications for magmatic processes at a slow spreading ridge a diverse volcanic and plutonic rock suite was recovered from the center of the 80 km long ridge segment of the southwest indian ridge 54 s 7 16 e between the islas orcadas and shaka fracture zones the cumulus nature of the gabbroic rocks in the suite is indicated by phase modal and cryptic layering igneous lamination and low incompatible element abundances we present a mass balance model for calculating the proportions and compositions of cumulus phases and crystallized intercumulus liquid from bulk rock major element compositions the model is based on the ability to define a compositional array of basaltic liquids and on the assumption that cumulus minerals are initially in equilibrium with trapped liquid calculated proportions of trapped liquid range from 3 15 values that are characteristic of adcumulates to mesocumulates models of postcumulus crystallization indicate significant enrichments of incompatible elements and buffering of compatible elements in residual trapped liquids thus explaining the high tio2 contents observed in magnesian clinopyroxenes cumulus phase assemblages and compositions suggest solidification in shallow level magma chambers but disequilibrium plagioclase compositions suggest some crystallization at greater depth furthermore basalt compositions projected onto the olivine clinopyroxenequartz pseudoternary suggest magma generation over a range of pressures from less than 10 to greater than 20 kb as well as polybaric fractional crystallization we suggest that the southwest indian ridge is characterized by low magma supply with small batches of melt that either ascend directly to the surface having undergone limited polybaric crystallization or are trapped in shallow crustal magma chambers where they evolve and solidify to form cumulate gabbros the adcumulus nature of the gabbros investigated here suggests slow cooling rates typical of large intrusions implying relatively large but ephemeral magma chambers below segments of the southwest indian ridge

the characteristics of blasting vibration frequency bands in jointed rock mass slope high slope and rock mass joint development are the factors for predicting and controlling blasting vibrations under open pit mining blasting vibration adversely affects the stability of jointed rock slopes thus studying the characteristics of blasting vibration frequency bands in jointed rock masses slope is an important task to ensure the safety of blasting operations in the present study vibratory ground motions were measured during blasting excavation in open pit mining and the blasting vibration frequency band characteristics of jointed rock masses and high slope were studied through the wavelet transform and response spectrum method the results demonstrated that the amplification effects of the peak particle velocity ppv and energy between different frequency bands exhibited distinguishing characteristics it was found that with the increase in elevation the ppv and energy amplification effects were the most obvious in the 0 16 hz band while they were attenuated in the 32 64 hz band furthermore the distribution of dominant frequency bands of vibration signals observed to be low and narrow and the average frequency had been reduced in the development of joints in rock masses the ppv and energy in each frequency band were attenuated and the distribution of the dominant frequency bands of vibration signals was high and wide also the average frequency had been increased and the multi modal characteristics of the responses to blasting vibrations were more obvious the rock mass structures had displayed different amplification effects on the frequency components of the blasting seismic waves finally as the effects of jointed rock masses on the blasting load responses could not be simply considered as reducing vibrations they must be analyzed using vibration theory and actual situations

an isotopic study of a fluvial lacustrine sequence the plio pleistocene koobi fora sequence east africa stable isotopic analyses of plio pleistocene and modern sediments in the fluvial lacustrine system occupying the turkana basin east africa provide constraints on the paleoenvironmental and diagenetic histories of the pliocene through the recent sediments in the basin the 13c values for carbonates in lacustrine sediments range from 15 to 22 relative to pdb depending on the varying proportions of co2 from the atmospheric reservoir and from various metabolic sources the 18o values of carbonates in lacustrine sediments indicate that the isotopic composition of paleolake water varied by over 10 from the pliocene to the present the 13c values for pedogenic carbonates record paleoccologic variations and suggest that c4 plants did not become well established in the preserved depositional parts of the basin until about 1 8 myr ago the 18o values pedogenic carbonates suggest a range of over 10 for the isotopic composition of soil water during this interval they also suggest a period of major climatic instability from about 3 4 to 3 1 myr and at about 1 8 myr together the 13c and 18o values of pedogenic carbonates indicate that the present conditions are as arid and hot as any that had prevailed during deposition of these plio pleistocene sediments

northeast african vegetation change over 12 m y intense debate surrounds the evolution of grasses using the c 4 hatch slack photosynthesis pathway and the emergence of african grasslands often assumed to be one and the same here we bring new insights with the combination of plant leaf wax carbon isotopic composition 13 c wax and pollen data from marine sediments of the gulf of aden northeast africa which show that c 4 biomass increases were not necessarily associated with regional grassland expansion we find broadly opposing trends toward more enriched 13 c wax values and decreased grass pollen proportions between 12 and 1 4 ma this apparently contradictory evidence can be reconciled if a greater proportion of the late miocene northeast african landscape were covered by c 3 grasses than previously thought such that c 4 grasses and shrubs replaced a c 3 ecosystem including trees and productive grasslands in addition 13 c wax and pollen both indicate that true rainforests were unlikely to have been extensive in northeast africa at any time in the last 12 m y although seasonally dry forests were a significant component of the regional landscape since the late miocene here we extend regionally integrative marine archives of terrestrial vegetation back to 12 ma and we evaluate them in the context of an updated compilation of pedogenic carbonate 13 c values from east african rift strata we identify two distinct phases of increasing c 4 biomass between 11 and 9 ma with a reversal by 4 3 ma and then a re expansion between 4 3 and 1 4 ma surprisingly neither was associated with grassland expansion

effect of aridity and rainfall seasonality on vegetation in the southern tropics of east africa during the pleistocene holocene transition fossil pollen analyses from northern lake malawi southeast africa provide a high resolution record of vegetation change during the pleistocene holocene transition 18 9 ka recent studies of local vegetation from lowland sites have reported contrasting rainfall signals during the younger dryas yd the lake malawi record tracks regional vegetation changes and allows comparison with other tropical african records identifying vegetation opening and local forest maintenance during the yd our record shows a gradual decline of afromontane vegetation at 18 ka around 14 5 ka tropical seasonal forest and zambezian miombo woodland became established at 13 ka drier more open formations gradually became prevalent although tropical seasonal forest taxa were still present in the watershed during the yd this drought intolerant forest type was likely restricted to areas of favorable edaphic conditions along permanent waterways the establishment of drought tolerant vegetation followed the reinforcement of southeasterly tradewinds resulting in a more pronounced dry winter season after 11 8 ka the onset of the driest most open vegetation type was coincident with a lake low stand at the beginning of the holocene this study demonstrates the importance of global climate forcing and local geomorphological conditions in controlling vegetation distribution

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

mapping surface deformation in open pit iron mines of carajas province amazon region using an integrated sar analysis abstract the carajas mineral province encompasses the world s largest iron reserves with excavation carried out through open pit benching mining operations in the area have significant areas of rock mass movements and surface displacements that potentially lead to slope instabilities with risks to personnel equipment and production instabilities can be expected due to deep excavations in rock masses of low geomechanical quality blasting practices and heavy precipitation in this paper ground instabilities are monitored through an integrated sar analysis based on a data stack of 33 terrasar x images this approach was designed to monitor distinct displacement regimes ranging from small to high deformation rates and to map surface changes based on variations of radar reflectivity results were compared with field information total station prisms ground based radar geological and geomechanical maps and the approach showed to be effective for monitoring ground deformation in the region due to its capabilities synoptic view high accuracy dense grid sampling the complementary use of space based sar with field monitoring systems proved to be strategic for operational mining planning and risk assessment in this challenging environment

seismological evidence for three dimensional melt migration beneath the east pacific rise the extent to which crustal processes along mid ocean ridges are controlled by either the pattern of mantle upwelling or the mode of magma injection into the crust is not known models of mantle upwelling vary from two dimensional passive flow1 to three dimensional diapiric flow2 3 4 similarly beneath a ridge segment bounded by tectonic offsets crustal magma chambers may be replenished continuously along the ridge5 6 7 or at a central injection zone2 3 4 from which magma migrates towards the segment s ends here we present tomographic images that reveal the seismic structure and anisotropy of the uppermost mantle beneath the east pacific rise the anisotropy is consistent with two dimensional mantle flow diverging from the rise whereas the anomalous isotropic structure requires a three dimensional but continuous distribution of melt near the crust mantle interface our results indicate that crustal magma chambers are replenished at closely spaced intervals along axis and that crustal systems inherit characteristics of scale from melt transport processes originating in the mantle

human topographic signatures and derived geomorphic processes across landscapes abstract the earth s surface morphology in an abiotic context is a consequence of major forcings such as tectonic uplift erosion sediment transport and climate recently however it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape even if at a different scale and magnitude from that of geology although the modern literature is flourishing on the impacts of vegetation on geomorphic processes the study of anthropogenic pressures on geomorphology is still in its early stages topography emerges as a result of natural driving forces but some human activities such as mining agricultural practices and the construction of road networks directly or indirectly move large quantities of soil which leave clear topographic signatures embedded on the earth s morphology these signatures can cause drastic changes to the geomorphological organization of the landscape with direct consequences on earth surface processes this review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape we explore different contexts that are significantly characterized by anthropogenic topographic signatures landscapes affected by mining activities road networks and agricultural practices we underline the main characteristics of those landscapes and the implications of human impacts on earth surface processes the final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology herein we focus on the role of high resolution topographic and remote sensing technologies the reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems this study may allow an improved understanding and targeted mitigation of the processes driving geomorphic changes during anthropogenic development and help guide future research directions for development based watershed studies human society is deeply affecting the environment with consequences on the landscape therefore establishing improved management measures that consider the earth s rapidly changing systems is fundamental

measurements of attenuation from vertical seismic profiles values of attenuation have been extracted from five detailed velocity surveys significant amounts of attenuation are observed in all five wells measured values of attenuation vary by a factor of 10 ranging from less than 0 1 to 0 9 db wavelength correlation of attenuation with lithology is good considering the resolution limits of the surveys one of the surveys was performed in west texas and the other four were carried out in the gulf coast area the total number of recording depths in each survey varied from 31 to 208 with downhole recordings taken every 10 or 20 ft over key stratigraphic zones in all five surveys a monitor geophone was placed near the well to check for source consistency our procedure for measuring attenuation involved constructing the spectral ratio between each downhole pulse and one particular reference pulse a value of cumulative attenuation ca was then extracted from each spectral ratio and plotted as a function of geophone depth this method allowed us to use many m

thermal effects of gabbro accretion from a deeper second melt lens at the fast spreading east pacific rise motivated by recent observations a ridge model has been developed which includes both a shallow melt lens and a second deeper melt lens above the moho to assess the thermal effect of the gabbro accretion from the lower melt lens at the fast spreading east pacific rise modeling results argue for a limited role of the lower melt lens in constructing the layer 3 gabbros if significant 10 amount of the layer 3 gabbros is emplaced near the moho then the liberated latent heat during crystallization would generate a large molten section of the lower crust due to the inability of cold seawater to penetrate into this hot ductile region a large molten section of the lower crust is not consistent with recent seismic tomographic results of the east pacific rise thus it is likely that the amount of the gabbro being emplaced from the lower melt lens at the epr is significantly less than that suggested by oman ophiolite studies such a lower melt lens is short lived or a large portion of the sill intrusions observed at oman was emplaced at a few kilometers off axis 3 4 km

east african climate change and orbital forcing during the last 175 kyr bp abstract variations in the temporal and spatial distribution of solar radiation caused by orbital changes provide a partial explanation for the observed long term fluctuations in african lake levels the understanding of such relationships is essential for designing climate prediction models for the tropics our assessment of the nature and timing of east african climate change is based on lake level fluctuations of lake naivasha in the central kenya rift 0 55 s 36 20 e inferred from sediment characteristics diatoms authigenic mineral assemblages and 17 single crystal 40ar 39ar age determinations assuming that these fluctuations reflect climate changes the lake naivasha record demonstrates that periods of increased humidity in east africa mainly followed maximum equatorial solar radiation in march or september interestingly the most dramatic change in the naivasha basin occurred as early as 146 kyr bp and the highest lake level was recorded at about 139 133 kyr bp this is consistent with other well dated low latitude climate records but does not correspond to peaks in northern hemisphere summer insolation as the trigger for the ice age cycles the naivasha record therefore provides evidence for low latitude forcing of the ice age climate cycles

mapping ground movements in open pit mining areas using differential sar interferometry the coherent pixel technique is an advanced differential sar interferometry technique that has been used for mapping and monitoring ground movements in la union mining area murcia se spain this technique was originally used to monitor mining subsidence in la union town but unknown ground instabilities were detected in an abandoned open pit mining area nearby measured displacements have been analyzed with respect to geometrical and geological factors that play a role in ground movements then a blind test consisting on geomorphological mapping of detected deformed areas was performed in order to identify the existence of unknown active processes slope instabilities and flat accumulation areas finally a detailed analysis of these results has permitted to illustrate the advantages and disadvantages of using this technique for mapping ground movements in mining areas

elevated pco2 leading to late triassic extinction persistent photic zone euxinia and rising sea levels the late triassic mass extinction event is the most severe global warming related crisis to have affected important extant marine groups such as scleractinian corals and offers potential insights into climate change scenarios here we present evidence from chlorobi derived biomarkers of episodic and persistent photic zone euxinia from biomarkers and stable carbon isotopes we present evidence of rapid mixing of atmospheric and oceanic carbon reservoirs global versus regional trends are resolved in kerogen organic matter type carbonate 13c and bulk and pyrite 34s this suite of data demonstrates for the first time a comprehensive organic and stable isotope geochemical reconstruction of events leading up to the late triassic extinction event and its aftermath the cascade of events prior to during and after the extinction is remarkably similar to those reported for the late permian extinction the largest extinction event of the phanerozoic we predict that similar conditions will have occurred during all past episodes of rapid global warming and biotic crisis that are associated with similar rises in p co2

using the gnss method assisted with uav photogrammetry to monitor and determine deformations of a dump site of three open pit marble mines in eliktekke region amasya province turkey the determination and monitoring of deformations that may occur in the benches of dump sites of open pit mines are important for both security and continuity of mine production the global navigation satellite system gnss is the most preferred method for deformation monitoring at dump sites while the amount of deformation 3d displacements can be determined at the points monitored by the gnss method interpretations on the cause and or areal size of the deformation may remain limited the main factors or triggering causes of slope failures at dump sites are base topography geometric dimensions width height and slope of the formed benches stiffness ratio of the dumped material and load increases caused by new dumps in the lower benches in this study uav photogrammetry and gnss were used together and the deformations at the adjacent dump site of three different open pit marble mines located in eliktekke region of amasya province in turkey were monitored the gnss method determined the points where displacements occurred and the uav photogrammetry searched for the causes of mobility at the point and its areal and volumetric sizes the uav photogrammetric results revealed that the topographic slope and overall slope inclination triggered the movement of the zones field measurements and evaluations made for this dump site showed that the current geometry should be kept where the overall slope inclination reaches 14 and not to be increased further the results support that the gnss method assisted with uav photogrammetry is a rapid and economical method to determine both the borders and volumetric sizes deformations as their causing parameters through the proposed methodology it will be possible to effectively determine the main factors causing slope failures in similar areas and to take the necessary measures on time

shear wave logging using guided waves the shear wave velocity of the formation is determined by logging the fastest component of the guided wave generated by the generating means this method is advantageous for logging the shear wave velocities of soft formations if the generating means of a multipole acoustic logging device radiates at frequencies including a critical frequency the fastest component of the guided wave generated by the generating means will have substantially the same velocity as a shear wave traveling in the earth formation by logging the velocity of this fastest component the shear wave velocity of the earth formation is determined

the amplitude and phase response of a seismic vibrator the amplitude and phase response of a simple model is compared with the performance of a real vibrator working in the field the field results show a characteristic phase response which confirms that the real drive force applied to the baseplate and its load impedance is faithfully represented by the acceleration of the reaction mass it follows that all the parameters necessary to calculate the load impedance and the true power dissipated in the earth can be measured at the output of the vibrator it also follows that the current method of baseplate phase compensation should be reconsidered

tooth enamel biomineralization in extant horses implications for isotopic microsampling abstract isotopic analyses of tooth enamel from fossil equids are increasingly being used to reconstruct paleoclimatic and paleoenvironmental conditions however the accuracy of these reconstructions is currently limited partly because the precise timing and spatial patterns of enamel mineralization in equids have not been documented we used radiographic analyses of mandibles collected from modern juvenile and adult domestic horses equus caballus to document the timing of enamel mineralization in equid cheek teeth premolars and molars optical and radiographic analyses of thin sections of mature and developing teeth were used to document the spatial pattern of enamel mineralization in each tooth we found that the enamel layers in equine cheek teeth took longer to mineralize than had been previously assumed largely because the enamel continued to mineralize for approximately 6 to 12 months after each tooth had begun to erupt total enamel mineralization times for individual teeth ranged from 1 5 to 2 8 years examination of thin sections revealed that retzius striae extend outward from the enamel dentin junction at an angle of 5 to 10 and run near parallel to the nonocclusal surface of the tooth daily cross striations average 5 m in width suggesting that during the initial phase of enamel mineralization matrix formation new material is added at a rate of 5 m day radiographic analyses demonstrate that the secondary mineralization front enamel maturation front is orientated approximately parallel to the retzius striae but complete maturation i e full mineralization lags behind matrix formation by several weeks to months

intra tooth stable isotope profiles in warthog canines and third molars implications for paleoenvironmental reconstructions abstract intra tooth stable isotope variations have been used to interpret seasonality and aridity in paleoenvironmental reconstructions of paleontological and archeological sites however most intra tooth datasets only permit qualitative interpretations of seasonality because the measured signal is attenuated due to the duration of enamel mineralization process and sampling geometry the common warthog phacochoerus africanus is an ideal organism to investigate stable isotope variation in enamel their canines grow continuously through the life of the individual and are therefore excellent candidates for mathematical modeling of seasonal signals and of signal attenuation further their isotope profiles a series of isotope measurements can be compared to isotope profiles of third molars m3 to provide insights into environmental reconstructions we first obtained paired intra tooth enamel samples from ever growing canines and hypsodont m3s of two extant common warthog specimens from laikipia kenya second from a different set of specimens we collected data on enamel growth patterns and geometry using histological thin sections and transmitted light microscopy and enamel mineralization parameters using micro ct scans in each tooth type third we reconstructed the timeline of unattenuated seasonal 18o signal from canine enamel using growth rate estimates and the inverse model of passey et al 2005 our results demonstrate that canines which capture 1 5 years of time exhibit near constant growth rates and simple enamel maturation geometry whereas m3s which also represent 1 5 years of time exhibit linearly decreasing growth rates and more complex maturation patterns we compare the timelines of unattenuated seasonal 18o signal and measured m3 profiles and find an average signal reduction of 50 in the m3s providing interpretations of the duration of seasonal cycles that are consistent 75 of the time we conclude that warthog canines are well suited for the inverse model approach and we established the model parameters for the forward and inverse methods timeline reconstructions based on m3 histology are promising for investigating the pattern of rainfall seasonality in the past finally we found an unexpected carbon isotopic spacing of 2 between canine and m3 enamel which suggests caution in interpreting 13c results from suid canine or molar enamel alone

seismic and aseismic slip evolution and deformation associated with the 2009 2010 northern malawi earthquake swarm east african rift summary interferometric synthetic aperture radar insar measurements field observations and elastic modelling of the 2009 2010 karonga northern malawi earthquake swarm reveal widespread coseismic and localized post seismic deformation in a period of about 1 5 months starting on november 5 29 m 4 earthquakes struck the region culminating in an mw 6 peak event on december 19 the next few months were characterized by significant localized deformation with a very low seismic moment release we find a very good agreement between insar and field observations of surface ruptures our best fitted coseismic models indicate dip slip displacements on a fault dipping 40 to the southwest with maximum slip of about 120 cm at 3 5 km depth fault activity continued until 2010 august as shallow aseismic afterslip mostly above the maximum coseismic slip patches although the swarm occurred within a coastal plain covered by porous quaternary sediments and a high water table the effect of poroelastic relaxation on the post seismic deformation was found to be negligibly small in contrast with other recent earthquake swarms along the east african rift the karonga swarm shows no evidence for dike intrusion

climatic patterns in equatorial and southern africa from 30 000 to 10 000 years ago reconstructed from terrestrial and near shore proxy data abstract as part of a wider study of last glacial and deglacial climates in the southern hemisphere continents we here review terrestrial and near shore marine records from equatorial and southern africa between 30 000 and 10 000 years ago 30 10 ka this time interval covers the lead up to the last glacial maximum lgm 21 2 ka the lgm proper and the ensuing deglacial records selected for review needed to meet three requirements continuity or near continuity over the period a well established chronology and at least one but preferably several unambiguous proxy ies we aim to show how regional climates of the sub continent have responded to orbital forcing as opposed to other global glacial interglacial boundary conditions and how they are related to high latitude climates sea and land surface conditions positions of the intertropical convergence zone itcz and of the westerly belt evidence of past climates derived from many independent proxies is given from west to southwest africa moisture from the atlantic ocean then from equatorial east africa to the southern subtropical summer rainfall domain moisture mainly from the indian ocean the lgm was cooler than today and generally drier in the tropics north of 8 9 s glacial to holocene increase in monsoonal precipitation primarily related to orbitally induced summer insolation in the northern hemisphere occurred by steps of increasing amplitude 17 16 14 5 11 5 ka major wet dry spells coincide with abrupt warm cold events in high northern latitudes and related itcz migrations in the southern tropics the main post glacial increase in tropical rainfall generally appears more gradual and in phase with antarctic warming data suggest a restricted northward migration of the itcz and concentration of tropical rainfall well south of the equator during the lgm and the younger dryas drier glacial conditions prevailed in southeastern africa while parts of southwestern africa point to enhanced humidity during the lgm suggesting that the winter westerly belt was either stronger than today or displaced further north possibly as a result of more extensive antarctic sea ice inferred african climatic fluctuations show the competing influences of tropical and high latitude climates of both hemispheres and suggest changes in both meridional and zonal circulation modes this review also reveals major geographical and methodological gaps and a number of unresolved issues providing pointers for future research

landslide detection integrated system ladis based on in situ and satellite sar interferometry measurements abstract an integrated system to analyze slope instabilities over vast areas through the intercomparison of measurements obtained by in situ and persistent scatterer ps interferometry processing of satellite synthetic aperture radar sar data is here introduced and tentatively named landslide detection integrated system ladis the persistent scatterer pair psp sar interferometry technique has been used to process high resolution sar images acquired in the 2008 2011 time span by the cosmo skymed satellite constellation available in a 40 km 40 km study area in the palermo province sicily region italy derived displacement rate estimates from cosmo skymedps measurements have been analyzed in approximately 10 of the study area for landslide research within this area according to the official landslide inventory map extremely slow to very slow landslides are dominant being favored by the presence of heterogeneous clay formations characterized by poor mechanical properties to prove cosmo skymedps displacement rates an engineering geological approach was adopted tailored to allow a continuous and rapid updating of landslide inventory maps to this aim a detailed geological field work has been performed to guarantee an independent assessment field surveys have been carried out without sharing information derived from ps data almost half 49 of the active unstable areas identified through cosmo skymedps measurements were confirmed by the field work in an additional 26 of cases the greater sensitivity of the satellite has allowed to identify movements even if very slow that did not show superficial evidence a confirmation of the great potentialities of the latest generation of satellite systems also comes from the comparison with the current official landslide inventory map updated in 2006 among the 58 of the total ps measurements that have been used to contour the landslides in remote 84 3 falls outside the polygons of the failures detected in the existing maps which implies a significant percentage of data to be associated to new landslides or extension of pre existing landslides advantages and drawbacks of exploiting cosmo skymed x band sar data to study landslides over wide areas through the proposed approach are finally discussed

advanced dinsar analysis on mining areas la union case study murcia se spain the town of la union se spain is located within a metal mining area that has been exploited since the roman period this historic exploitation has left behind a high concentration of abandoned underground mining galleries currently an industrial area is subsiding due to the collapse of one of these galleries in may 1998 in this paper an advanced differential interferometry sar dinsar method called the coherent pixels technique cpt has been used to study the subsidence phenomena for two time intervals from january 1998 to december 2000 and from march 2003 to december 2004 dinsar derived deformation maps have enabled the detection and monitoring of different deformation processes that affect several locations within the study area by comparing these results with the underground mining galleries map a clear relationship between their presence and the subsidence has been proved deformation values retrieved with dinsar between april 2003 and december 2004 have been compared with the topographical leveling network measurements performed in this same period providing an absolute average difference of 0 7 cm with a standard deviation of 0 5 cm results obtained in the city of la union have shown that the advanced dinsar technique is able to provide very useful spatial and temporal deformation data for the measurement of small scale subsidence throughout short time periods this technique has enabled the temporal evolution of the phenomena in the city of la union to be studied and understanding of subsidence to be expanded beyond the limits of a deployed topographical control network in a more cost effective way than classical methods

origin of pegmatitic segregation veins within flood basalts subhorizontal veins and lenses of coarse grained rock composed of plagioclase augite and fe ti oxides in a glassy and vesicular mesostasis occur within several thick subaerial basalt flows in the columbia river basalt province of washington and in the eastern north american mesozoic basalt province the veins and lenses referred to as pegmatitic segregation veins are typically 1 10 cm thick and are enriched in fe ti k p cu zr ba and ree by a factor of about 1 1 to 3 over the host basalt al ca sr mg ni and cr are lower and si and na are typically unchanged we interpret the pegmatitic segregation veins as the product of residual melt carried in vapor bubbles from the lower crystallization front of partially crystallized flows to the crystal mush within the upper crystallization front movement through the elevated temperatures of flow interiors fused any crystal nuclei in the segregation melt diminished nucleation density during crystallization may partially account for coarse grain sizes in addition diffusion of ions to large rapidly growing skeletal crystals was probably enhanced by the viscosity reduction effect of water enrichment the water content of accumulated segregation melt may have increased whenever the escape of volatiles from partiallymore crystallized flows was temporarily sealed off under a rigid barrier of solidified basalt rupture of the barrier by downward propagation of columnar joints would allow the resumption of effervescence and any remaining partially crystallized segregation melt phase would be degassed and quenched into a glassy and vesicular mesostasis 59 refs 8 figs 2 tabs less

piezoelectric seismic vibration device and method a vibrator and method for transmitting seismic signals into the earth to obtain data on various subsurface characteristics the vibrator is driven with piezoelectric transducers which can operate below 500 hz and can produce better signal resolution at higher frequencies than is possible with hydraulic vibrators the piezoelectric vibrators can be used in various embodiments at the earth s surface within a borehole or while permanently buried in the earth

spatiotemporal monitoring of surface motions using dinsar techniques integrated with geological information a case study of an iron mine in the amazon region using terrasar x and radarsat 2 data instabilities are extremely common in the iron open pit mines located in the carajas mineral province the world s largest iron reserves located in the brazilian amazon due to deep excavations in rock products of low geomechanical quality heavy precipitation and blasting practices mining operations in the area present surface displacements that potentially lead to slope instabilities with several risks personnel equipment mining infrastructure etc this paper presents the results related to the n5e mine based on dinsar time series dts and persistent scatterer interferometry psi using a temporal series of 33 stripmap terrasar x sm tsx images and geological information provided from a 3d photointerpretation of an sm tsx and ultra fine radarsat 2 uf rst stereo pair calibrated with field data measurement point dts psi results were compared with in situ geodetic survey information total station prism measurements and showed good agreement indicating that most of the mine can be considered stable during the period of the tsx coverage the highest accumulated displacements were spatially related to a thematic unit mapped as a landfill for other sectors of the mine lower deformation rates were related to photointerpreted lineaments related to the carajas fault system suggesting that geological structures can play a key role in controlling some surface displacements the investigation demonstrated that the strategy based on the use of dts and psi techniques integrated with geological data provided a synoptic view of the deformation process that affected the mine the approach was relevant for ground displacements monitoring of the study area with dinsar results compared with in situ geodetic measurements showing good statistical correlation

monitoring of remedial works performance on landslide affected areas through ground and satellite based techniques abstract differential interferometric synthetic aperture radar dinsar techniques have repeatedly proved to be an effective tool for built environments monitoring in areas affected by geological hazards this paper describes how the coherent pixel technique cpt approach has been successfully applied to assess the response of an unstable slope to the different phases of remedial works following a landslide event the cpt technique was performed on 59 cosmo skymed images obtained between may 2011 and august 2016 and centred on the quercianella settlement a small hamlet of livorno municipality tuscany italy where the reactivation of a dormant shallow slide had occurred in march 2011 and hereafter a geotechnical intervention designed with the aim of mitigating the risks has been conducted from august 2013 lasting thirteen months the time series of cpt results show a deformation pattern with sudden accelerations up to 21 mm in few months corresponding to the beginning of the interventions during which the area has been excavated to install a drainage well followed by mild decelerations resulting from the stabilization of the area after the conclusion of the works in particular the integration of ground based subsurface monitoring inclinometers and piezometers and dinsar superficial data has provided consistent results for landslide characterization and helped defining the state of activity and the areal distribution of the sliding surface moreover the performance of remedial works in the landslide affected area has been observed showing stabilization in the upper part of the hamlet and the ongoing movement in the lower part the combined monitoring system also led the geotechnical company in charge of remedial works to design further stabilization works in order to preserve buildings and roads in the moving area therefore the integration of remote sensing techniques and in situ instruments represents a timely and cost efficient solution for intervention works monitoring opening new perspectives on designing engineering solutions for the stabilization of unstable slopes

downhole electromagnetic seismic source a downhole seismic source 20 capable of generating seismic forces in excess of 1000 newtons the source produces seismic waves for seismic applications particularly cross borehole measurements and vertical seismic profiling coupled with motion sensing devices the present invention also performs as a seismic logging tool the source is comprised of an outer housing 32 a means 60 for clamping the source securely to the wellbore and a linear electromagnetic actuator 30 which utilizes permanent magnetic material having remanent magnetic field exceeding about 9 t such as rare permanent magnetics the source has a diameter of about 12 5 cm to fit within a typical wellbore and the actuator has a length of about 1 meter

african climate change and faunal evolution during the pliocene pleistocene abstract environmental theories of african faunal evolution state that important evolutionary changes during the pliocene pleistocene interval the last ca 5 3 million years were mediated by changes in african climate or shifts in climate variability marine sediment sequences demonstrate that subtropical african climate periodically oscillated between markedly wetter and drier conditions paced by earth orbital variations with evidence for step like 0 2 ma increases in african climate variability and aridity near 2 8 ma 1 7 ma and 1 0 ma coincident with the onset and intensification of high latitude glacial cycles analysis of the best dated and most complete african mammal fossil databases indicates african faunal assemblage and perhaps speciation changes during the pliocene pleistocene suggesting more varied and open habitats at 2 9 2 4 ma and after 1 8 ma these intervals correspond to key junctures in early hominid evolution including the emergence of our genus homo pliocene pleistocene shifts in african climate vegetation and faunal assemblages thus appear to be roughly contemporary although detailed comparisons are hampered by sampling gaps dating uncertainties and preservational biases in the fossil record further study of possible relations between african faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries emerging molecular biomarker methods for reconstructing african paleovegetation changes tephra correlations between terrestrial and marine sequences as well as continuing collaborations between the paleoclimatic and paleoanthropological communities