elasticity and pressure induced structural changes in vitreous mgsio3 enstatite to lower mantle pressures abstract knowledge of the pressure density relations and elastic properties of silicate melts at high pressure and temperature conditions is fundamental for a better understanding of the dynamics and properties of the earth s interior here we report the sound velocities and elastic properties of vitreous mgsio 3 enstatite a simple analog for melts in the earth s mantle determined up to 33 4 1 2 gpa in a diamond anvil cell by brillouin scattering spectroscopy the adiabatic bulk and shear moduli of mgsio 3 glass at ambient conditions are k s0 78 4 6 gpa and 0 41 1 3 gpa corresponding to compressional and shear wave velocities of v p 6 969 30 km s and v s 3 868 20 km s on compression both longitudinal v p and transverse v s modes exhibit anomalous change in slope at 8 gpa and between 15 0 1 and 17 9 2 gpa that are associated with polyamorphic phase transitions in the glass the acoustic data were used to determine the density and compressibility of mgsio 3 glass at high pressure in both compression and decompression experiments in contrast to velocities and elastic moduli the density increases smoothly without singularities upon compression over the investigated pressure range densities of recovered glasses at room pressure are 1 5 to 2 4 higher than uncompressed glasses indicating pressure induced irreversible densification the anomalous changes in velocities and compressibility with pressure are consistent with structural modifications that have been identified as the main densification mechanisms of the glass by in situ spectroscopic studies and molecular dynamic calculations the results suggest that the residual densification of recovered glasses is associated with irreversible structural changes in the intermediate range order i e ring statistics rather than with changes in the coordination number of si upon pressurization if the changes in compressibility of mgsio 3 glasses identified in the present brillouin study also occurs in the analog melts they may have important implications for the present day dynamics of the mantle and early evolution of the earth during a magma ocean phase

late pleistocene extension and strike slip in the dead sea basin a newly discovered active small scale pull apart mor structure located in the western part of the dead sea basin shows recent basin parallel extension and strike slip faulting and offers a rare view of pull apart internal structure the mor structure is bounded by n s trending strike slip faults and cross cut by low angle e w trending normal faults the geometry of this pull apart suggests that displacement between the two stepped n s strike slip faults of the mor structure is transferred by the extension associated with the normal faults the continuing deformation in this structure is evident by the observation of at least three deformation episodes between 50 ka and present the calculated sinistral slip rate is 3 5 mm yr over the last 30 000 years this slip rate indicates that the mor structure overlies the currently most active strike slip fault within the western border of the dead sea pull apart the mor structure is an example of a small pull apart basin developed within a larger pull apart this type of hierarchy in pull apart structures is an indication for their ongoing evolution

geometric changes of plate boundaries along part of the northern dead sea transform geochronologic and paleomagnetic evidence the korazim block an elevated pressure ridge along with the faults bounding the sea of galilee and hula pull apart basins are internal structures of the dead sea transform plate boundary k ar dates and paleomagnetic data from basalt flows and sedimentary strata are utilized to determine the stratigraphy and the deformation of the region the integration of the two methods together with structural data yield high resolution age determination of the stratigraphic sequence and provides insight into the timing and style of deformation the korazim block is covered in its southern and central areas by pliocene basalt flows the cover basalt 5 1 3 6 ma and ruman basalt 2 9 2 2 ma formations and in its northern area by basalts yarda basalt 0 9 0 8 ma and sediments 3 0 2 3 and 1 6 0 9 ma of plio pleistocene age the magnetic polarity of a total of 29 lava flows and intercalated sedimentary strata is mixed the mean magnetic declination of the 29 sites shows an anomalous direction which yields 11 4 4 0 counterclockwise rotation with respect to the expected field the mean inclination of 46 0 4 1 does not significantly deviate from the expected field the anomalous declination is interpreted as the consequence of faulting and block rotation accommodating internal deformation this deformation did not begin before late pliocene to early pleistocene probably not before 0 9 ma and may still be active simultaneous right lateral slip of 50 175 m with a small reverse component of 30 90 m along nw trending faults and 11 counterclockwise rotation created internal deformation of the korazim pressure ridge this deformation is the consequence of left lateral slip along the almagor strand of the dead sea transform subparallel to the plate slip vector thus a compression component was formed which presumably led to the internal deformation of the korazim block the recent deformation of the korazim block in relation to the age of adjacent structures and to the age of the dead sea transform permits temporal resolution of geometric changes which must typify transform boundaries such as the dead sea transform internal structures within transforms may change along with the transform internal geometry and become inactive while new structural features may develop

the elat aqaba dead sea jordan subgraben system abstract the elat dead sea jordan rift zone is divided into distinct subgrabens these subgrabens are separated from one another by pivotal uplifted areas the subgrabens are usually asymmetric with the sense of asymmetry changing from west to east and vice versa along the length of the rift zone most faults are meridional n s trending or submeridional nne ssw trending transverse faulting is extremely rare thus opposing the key stone theory and also the fashionable rhomb chain model our levantine chain of subgrabens are but an infra pleistocene initial stage in the afro arabian rift system

new discoveries at the middle pleistocene acheulian site of gesher benot ya aqov israel abstract the gesher benot ya aqov archaeological site in the northern dead sea rift of israel contains acheulian artifacts and middle pleistocene fossils initial results of a new interdisciplinary study have shown that fluviolacustrine sediments of the benot ya aqov formation which contains several archaeological occupations were deposited in an embayment of the hula basin they were subsequently deformed by tectonic activity associated with the dead sea rift biostratigraphy magnetostratigraphy and k ar dating serve to constrain the age of the benot ya aqov formation to between 240 000 and 730 000 yr b p archaeological excavation of three areas and two trenches at the new study area have produced abundant basalt flint and limestone artifacts mammalian and avian fossils and considerable plant material the lithic materials provide an excellent opportunity to study large assemblages of in situ acheulian artifacts a rare phenomenon in the middle pleistocene levantine record in addition the organic materials will facilitate paleoenvironmental reconstructions from an ecological floral perspective

the genesis of mid ocean ridge basalt the tholeiitic volcanics erupted at mid ocean ridges mid ocean ridge basalts or morb constitute the dominant volcanic lithology on earth analyses of tachylites from atlantic pacific and indian ocean spreading centres range widely in 100 mg mg fe2 ratios m and m varies from 70 to 30 glasses with m 55 65 are the most common variants and only a small percentage of glass analyses has m approaching 70 the latter defines the m value of basaltic melts in equilibrium with residual upper mantle source peridotites with m 88 the frequency histogram of the m values of average compositions of morb glasses at 88 ocean floor localities is similar in analysis distribution to the frequency histograms depicting variation in the m values of glasses from the various spreading centres m values and nickel contents of morb and the nature and compositions of the near liquidus phases crystallized experimentally from morb melts at elevated pressures have been applied to identify primary unfractionated melts erupted in a mid ocean ridge environment however ni abundances and high pressure phase relationships are not necessarily unique or definitive parameters of primary melts the latter are generally linked genetically with mg rich lherzolitic source rocks of pyrolite type m 90 the spectrum of m values displayed by morb glasses with a definite bias towards relatively fe rich compositions average m of approximately 600 morb glasses is 58 6 suggests that the melts may have evolved either via ferromagnesian fractionation of relatively mg rich parental melts m 70 80 or by partial melting of a heterogeneous upper mantle with variable m values or as a result of magma mixing of already fractionated melts and primitive magma batches for a number of reasons fractonation models based on the extraction of olivine or one or more of olivine plagioclase and clinopyroxene either from picritic melts m 75 or primitive basaltic melts with m 70 are questionable as prime controls of morb chemistry these include 1 the extreme rarity of quenched picritic or mg basaltic melts in ocean ridge environments 2 the lack of adequate evidence of the appropriate of necessity voluminous complementary cumulates dunites allivalites troctolites anorthosites demanded by olivine plagioclase or olivine plagioclase fractionation models and 3 the aberrent frequencies of glass m values whereby the assumed derivatives m 55 65 are much more abundant and presumably much more voluminous than the alleged parents or transitional derivatives 65 m 75 the nature of the trends of na2o cao and al2o3 in galapagos spreading centre tachylites of extended composition m 65 30 indicates the gabbroic fractionation is also unlikely to exert important controls on morb chemistry as their m values increase mid ocean ridge basalts increase in al ca ni co cr and decrease in ti mn na k and p except for al and ca these trends are similar to those displayed by upper mantle peridotites increasing in m i e becoming more refractory following one or more partial melting episodes it is suggested that at least a majority of mid ocean ridge basalts is intrinsically primary and generated by variable degrees of partial melting of heterogeneous lherzolitic upper mantle 80 m 90 with variable abundances of elements such as ti al ca and na and also depleted in large ion lithophile lil elements negative europium anomalies in the rare earth patterns of some oceanridge basalts ferrobasalts with low m are ascribed mainly to the persistence of residual plagioclase in relatively fe rich plagioclase lherzolite source rocks following low degrees of partial melting the partial melting events leading to the generation of mid ocean ridge basalts took place over a relatively modes pressure range approximately 8 15 kb which encompassed the transition of plagioclase lherzolite to spinel lherzolite this proposal appears consistent with the nature and occurrence of megacrysts xenocrysts of tschermakitic cr diopside ca43mg52fe5 olivine mg 89 91 plagioclase an92 85 and spinel fe2al60cr38 in some morb the megacryst compositions suggest that these phases represent disaggregated plagioclase peridotite or spinel lherzolite acquired by melts during their passage through the oceanic upper mantle

new k ar ages of basalts from the harrat ash shaam volcanic field in jordan implications for the span and duration of the upper mantle upwelling beneath the western arabian plate the volcanism in the western arabian plate extends from the red sea through the harrat ash shaam system to western syria as far north as the bitlis suture in the taurides the harrat ash shaam volcanic system in jordan consists of northwest trending dikes and a volcanic field that together encompass a width of 220 km in terms of width direction and age of the main volcanic phases the system is similar to the red sea dike belt about 130 new k ar age determinations show that the ages of the harrat ash shaam system dikes and flows range from oligocene to quaternary however there is a distinct gap in the ages between 22 and 13 ma this gap coincides with an apparent decrease in volcanism in the red sea region from around 20 to 12 ma we interpret this 9 m y gap as a quiescent period interrupting the volcanic activity in the region and suggest that from 22 to 13 ma tectonic activity in the arabian plate was mainly restricted to the red sea region a renewal of volcanism along the western margins of the arabian plate at 13 ma was very likely associated with the sinistral movement along the north trending dead sea transform this renewal of volcanism and tectonic activity may reflect the emergence of upper mantle upwelling beneath the western arabian plate at that time

statistical analysis of mineral diversity and distribution earth s mineralogy is unique abstract earth s mineralogical diversity arises from both deterministic processes and frozen accidents we apply statistical methods and comprehensive mineralogical databases to investigate chance versus necessity in mineral diversity distribution relationships hundreds of mineral species including most common rock forming minerals distinguish an earth like planet from other terrestrial bodies however most of earth s 5000 mineral species are rare known from only a few localities we demonstrate that in spite of deterministic physical chemical and biological factors that control most of our planet s mineral diversity earth s mineralogy is unique in the cosmos

evolution of the stress field near the arava basin located along the dead sea fault system as revealed by joint sets abstract to reveal the development of the stress field near the arava basin located along the dead sea fault system we characterized joint sets that were exposed mainly in the santonian and eocene chalk rock outcropping in the study area in total 2600 strike orientations of single layer joints slj and multilayer joints mlj mirrored four main stress fields 1 hnw j1 326 2 hnnw j2 343 3 hnne j3 033 and 4 hn j4 360 the results showed that the relatively lower values of the fracture spacing ratio fsr and their standard deviations in j1 implied that j1 was formed during the burial stage of the eocene chalk formations the inconsistency between the statistical parameters of the log normal distributions of joint spacing and fsr raised doubt about the applicability of the saturation joint density model in our studied area the joint sets characteristics suggest that the regional hnw operated during the eocene during the miocene the regional stress field changed clockwise to hnnw probably in association with the early stage of transform motion along the dead sea fault in the pliocene pleistocene the hnne and hn local stress fields both operated and were accompanied by a tensional stress field that can be identified in the intensive normal faulting evolved along the western arava basin margins

implications of the wadi al hammeh sequences for the terminal drying of lake lisan jordan abstract the ancestral valley of the wadi al hammeh in northwestern jordan is backfilled by a 60 m thick body of sediment a comprehensive series of radiocarbon dates and in situ archaeological sites ranging in age from middle palaeolithic to epi palaeolithic show that the sedimentary sequence is a lateral continental equivalent to the lisan formation the geometry and sedimentological character of the sequence indicate that backfilling of the wadi was in response to a gradual rise in lake levels until about 11 100 yr b p the clearly defined lithofacies variations and the uniformity of sedimentary sequences implies no significant drop in lake levels occurred between 31 000 and 11 100 yr b p the present topography arises from incision of the wadi sequences in response to lowered base levels of sedimentation following the drying of the lake at about 11 000 yr b p the presence at the mouth of the wadi of low energy calcareous silts with melanopsis shell layers dated between 15 000 and 19 000 yr b p at levels some 30 40 m above the highest levels reached by lake lisan 180 m is attributed to post lisan tectonism

on the nature and significance of rarity in mineralogy more than half of the 5000 approved mineral species are known from five or fewer localities and thus are rare mineralogical rarity arises from different circumstances but all rare mineral species conform to one or more of four criteria 1 p t x range minerals that form only under highly restricted conditions in pressure temperature composition space 2 planetary constraints minerals that incorporate essential elements that are rare or that form at extreme conditions that seldom occur in earth s near surface environment 3 ephemeral phases minerals that rapidly break down under ambient conditions and 4 collection biases phases that are difficult to recognize because they lack crystal faces or are microscopic or minerals that arise in lithological contexts that are difficult to access minerals that conform to criterion 1 2 or 3 are inherently rare whereas those matching criterion 4 may be much more common than represented by reported occurrences rare minerals though playing minimal roles in earth s bulk properties and dynamics are nevertheless of significance for varied reasons uncommon minerals are key to understanding the diversity and disparity of earth s mineralogical environments for example in the prediction of as yet undescribed minerals novel minerals often point to extreme compositional regimes that can arise in earth s shallow crust and they are thus critical to understanding earth as a complex evolving system many rare minerals have unique crystal structures or reveal the crystal chemical plasticity of well known structures as dramatically illustrated by the minerals of boron uncommon minerals may have played essential roles in life s origins conversely many rare minerals arise only as a consequence whether direct or indirect of biological processes the distribution of rare minerals may thus be a robust biosignature while these phases individually and collectively exemplify the co evolution of the geosphere and biosphere finally mineralogical rarities as with novelty in other natural domains are inherently fascinating

the dead sea rift from continental rift to incipient ocean abstract the dead sea rift is a 600 km long approximately 20 km wide geomorphological depression showing a topographic relief of 1 000 to 3 000 m from the axial depression to the mountainous margins in many places the rift is the northern extension of the red sea young oceanic spreading centre and it is built of a series of internal basins the rift is the product of vertical displacements that downfaulted its floor and uplifted its margins but some sinistral strike slip offset affected the rift as well the tectonic evolution of the rift started probably in the pliocene subsequent to the termination of the intensive tectonic activity in the suez rift the transition of the tectonic activity from suez rift to the dead sea rift is due to a probable clockwise jump of the northern extension of the red sea spreading centre the dead sea rift with its internal basins and faulted precipitous escarpments presents an exceptional example for the earliest stages of the evolution of continental break up and of nascent passive continental margins tectonic interpretations of the voluminous geological and geophysical data from the rift and its margins are complicated because the information is equivocal part of the data suggests that the rift is an extensional structure whereas another part indicates that the rift is a product of regional sinistral strike slip faulting however it is suggested that the equivocal data are not necessarily conflicting because the evolution of the rift is probably associated with oblique resultant displacement of combined normal and strike slip faulting the quantitative ratio between the extensional and the lateral offset processes in the dead sea rift is controversial there is ground to presume that large downfaulting of the rift floor and intensive erosion of its uplifted margins removed and obscured critical data that could have provided reliable correlation between the eastern and western flanks nevertheless reconstruction of mesozoic depositional fades zones across the rift apparently indicates that the lateral displacements are approximately 10 km and seismic reflection profiles suggest vertical offsets reaching 7 km the series of secondary internal basins in the rift that seem equivalent to the linear system of axial basins in the northern red sea support the concept that the dead sea is under a tectonic regime that is comparable to the one that affected the red sea in the miocene these findings and the 25 to 50 reduction of crustal thicknesses underneath the rift indicate an incipient oblique oceanic spreading centre

comparison of enigmatic diamonds from the tolbachik arc volcano kamchatka and tibetan ophiolites assessing the role of contamination by synthetic materials abstract the enigmatic appearance of cuboctahedral diamonds in ophiolitic and arc volcanic rocks with morphology and infrared characteristics similar to synthetic diamonds that were grown from metal solvent requires a critical reappraisal we have studied 15 diamond crystals and fragments from tolbachik volcano lava flows using fourier transform infrared spectrometry ftir transmission electron microscopy tem synchrotron x ray fluorescence srxrf and laser ablation inductively coupled plasma mass spectrometry la icp ms ftir spectra of tolbachik diamonds correspond to typical type ib patterns of synthetic diamonds in tem films prepared using focused ion beam technique we find mn ni and mn si inclusions in tolbachik diamonds srxrf spectra indicate the presence of fe ni and fe ni mn inclusions with cr ti cu and zn impurities la icp ms data show variable but significantly elevated concentrations of mn fe ni and cu reaching up to 70 ppm these transition metal concentration levels are comparable with those determined by la icp ms for similar diamonds from tibetan ophiolites mn ni fe solvent was widely used to produce industrial synthetic diamonds in the former ussr and russia with very similar proportions of these metals hence it appears highly probable that the cuboctahedral diamonds recovered from kamchatka arc volcanic rocks represent contamination and are likely derived from drilling tools or other hard instruments kinetic data on diamond dissolution in basaltic magma or in fluid phase demonstrate that diamond does not form under the pressures and temperature conditions prevalent within the magmatic system beneath the modern day klyuchevskoy group of arc volcanoes we also considered reference data for inclusions in ophiolitic diamonds and compared them with the composition of solvent used in industrial diamond synthesis in china the similar inclusion chemistry close to ni70mn25co5 for ophiolitic and synthetic chinese diamonds scrutinized here suggests that most diamonds recovered from tibetan and other ophiolites are not natural but instead have a synthetic origin in order to mitigate further dubious reports of diamonds from unconventional tectonic settings and source rocks we propose a set of discrimination criteria to better distinguish natural cuboctahedral diamonds from those produced synthetically in industrial environments and found as contaminants in mantle and crust derived rocks

geochemistry of tholeiites from lanai hawaii lanai is the third smallest of the fifteen principal subaerial shield volcanoes of the hawaiian hotspot this volcano apparently became extinct during the shield building stage of volcanism as shown by the absence of both alkalic cap and post erosional lavas major and trace element analyses of 22 new samples collected primarily from 3 stratigraphic sections show that lanai tholeiites span a large range in composition some lanai lavas are unique geochemically among hawaiian tholeiites in having the lowest abundances of incompatible trace elements of any hawaiian lavas and well developed positive eu anomalies the geochemical characteristics of these low abundance lanai tholeiites are not the result of alteration differences in mantle source modal mineralogy the presence of residual accessory mantle phases or fractional crystallization of such phases assimilation of depleted morb wall rock or accumulation resorption of phenocrysts or xenocrysts incompatible trace element ratios e g nb la nb th la th la hf ce pb in lanai tholeiites span considerable ranges and form coherent trends with each other and with absolute abundances of these elements large variations in la sm la yb and absolute ree abundances at constant mgo suggest that lanai tholeiites formed by variable amounts of partial melting however large ranges in incompatible element ratios cannot be explained solely by variations in partial melting of a geochemically homogeneous source but must reflect geochemical heterogeneities in the lanai source partial melting modeling indicates that the mixed lanai source is probably lree enriched i e la yb cn 1 one component in the lanai source exemplified by the low abundance tholeiites has markedly lower ree hfse th hfse alkali hfse and ce pb ratios than other lanai or hawaiian tholeiites and may indicate the presence of recycled residual subduction zone materials in the hawaiian plume source the positive eu anomalies that characterize the low abundance lanai tholeiites are not the result of plagioclase accumulation or assimilation but are a feature of this source component progressive temporal geochemical variations in lanai tholeiites from 2 stratigraphic sections indicate that the source composition of these lavas probably evolved over time this change could have resulted from a progressive decrease in the extent of partial melting of the lanai source the compositional variability of lanai tholeiites suggests that geochemical heterogeneities in their source are larger than the scale of partial melting lanai tholeiites could not have formed by smaller degrees of partial melting of plume material than did the larger volume hawaiian shields therefore volume differences between hawaiian shields must be controlled primarily by differences in the volume of supplied plume material rather than by differences in the degree of partial melting the premature cessation of eruptive activity at lanai may be attributed to relatively large degrees of partial melting of a small plume

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

structural control on drainage network and catchment area geomorphology in the dead sea area an evaluation using remote sensing and geographic information systems in the wadi zerka ma in catchment area jordan the geology of jordan is characterized by fault systems with three major trends 1 nw se the oldest 2 wnw ese and 3 nnw sse the youngest the drainage network of the wadi zerka ma in catchment area located in the middle of the dead sea rift parallels these structural orientations a regional transtensive fault with embedded normal faults bounds the lower and middle part of the catchment area the topographic profile of the zerka ma in river exhibits two major knickpoints where it crosses two major embedded normal faults the second major knickpoint developed as a result of the dramatic lowering of the lisan lake water level a lake that pre dates the dead sea the decreased water level triggered river incision into the clastic sandstone units of wadi zerka ma in we performed a morphotectonic analysis study to investigate how the rock structures control the drainage network and the catchment area geomorphology according to the transverse topographic symmetry factor t the catchment area is highly asymmetric the major basin asymmetry trend is se oriented parallel to the oldest set of fault systems the catchment area displays a convex hypsometric curve indicating a very recent stage in the geomorphologic cycle our study indicates that the lisan lake catchment area shrinkage and structures growth controlled and shaped the wadi zerka ma in catchment area geomorphology the combined use of a geographic information system gis and remote sensing was shown to be very efficient in unraveling the evolution of the drainage network and catchment area geomorphology

exhumation of lower mantle inclusions in diamond atem investigation of retrograde phase transitions reactions and exsolution a multiphase inclusion kk 83 in a diamond from the kankan deposits in guinea resulting from complex reactions between primary lower mantle phases was examined in detail using analytical transmission electron microscopy the inclusion consists of a large 300 m diopside crystal with a small symplectitic intergrowth in one corner comprising olivine and tetragonal almandine pyrope phase tapp the olivine part of the symplectite contains small exsolutions of mg al chromite and rare ca carbonate a second inclusion of ferropericlase observed in the same diamond indicates a primary origin within the lower mantle the clinopyroxene formed through a series of reactions at the expense of touching inclusions of casi and mgsi perovskite during convective ascent of the diamond through the transition zone the proposed reaction sequence is mgsipvk casipvk mgsiilm casipvk ringwoodite stishovite casipvk clinopyroxene relict ringwoodite the high al content of the bulk symplectite indicates ringwoodite as precursor phase coexisting with clinopyroxene a slight deficiency of sio2 during the diopside forming reaction leads to a small amount of relict ringwoodite 0 1 vol of the total inclusion is occupied by ringwoodite coexisting with diopside the ringwoodite captures the observed high amount of al subsequent breakdown of ringwoodite to wadsleyite tapp produces the observed symplectitic intergrowth during the phase transformation of wadsleyite to olivine exsolution of mg al chromite occurs further decreasing the original solubility of al cr and ti in accordance with experimental data on the element partitioning between wadsleyite and olivine based on these observations tapp can form as a retrograde phase within the transition zone of the earth s mantle and is not restricted to the upper part of the lower mantle high fe3 contents may favour its formation

undepleted mantle composition beneath hawaii compositions of undepleted mauna loa mantle have been calculated assuming derivative residuum relations between a tholeiitic picrite from the 1852 eruption of mauna loa and mantle residua whose compositions are delineated by experimental data and the compositions of the most refractory picrite phases namely mg rich olivine and cr rich spinel the preferred calculated composition based on 40 picrite 60 residuum composed of olivine orthopyroxene and cr spinel has a lower 100 mg mg fe ratio 84 1 than the ratios of pyrolite like undepleted mantle compositions 88 90 and compared with many such compositions it also has significantly higher abundances of tio2 al2o3 cao na2o k2o and p2o5 the higher abundances of incompatibles have implications for the volumes and character of potential derivative melts a calculated mode which assumes that a titaniferous pargasitic amphibole is a component of the undepleted lherzolite indicates that amphibole could be a significant primary phase at temperatures slightly above the lherzolite solidus amphibole would be eliminated on incongruent melting and its breakdown products mainly clinopyroxene plus minor olivine would become part of a re equilibrated anhydrous peridotitic mineral assemblage the lower 100 mg mg fe ratio of the calculated composition would permit the generation of primary basaltic melts with relatively low 100 mg mg fe2 ratios at lower 40 degrees of melting such lower ratios are usually attributed to olivine fractionation of more mg rich primary melts from pyrolite like mantle sources

earth s missing minerals recent studies of mineral diversity and distribution lead to the prediction of 1563 mineral species on earth today that have yet to be described approximately one fourth of the 6394 estimated total mineralogical diversity the distribution of these missing minerals is not uniform with respect to their essential chemical elements of 15 geochemically diverse elements al b c cr cu mg na ni p s si ta te u and v we predict that approximately 25 of the minerals of al b c cr p si and ta remain to be described a percentage similar to that predicted for all minerals almost 35 of the minerals of na are predicted to be undiscovered a situation resulting from more than 50 of na minerals being white poorly crystallized and or water soluble and thus easily overlooked in contrast we predict that fewer than 20 of the minerals of cu mg ni s te u and v remain to be discovered in addition to the economic value of most of these elements their minerals tend to be brightly colored and or well crystallized and thus likely to draw attention and interest these disparities in percentages of undiscovered minerals reflect not only natural processes but also sociological factors in the search discovery and description of mineral species

enigmatic super reduced phases in corundum from natural rocks possible contamination from artificial abrasive materials or metallurgical slags abstract recently a number of reports claimed enigmatic appearance of high pressure and super reduced minerals in ophiolitic chromitite and peridotite diamond moissanite various metal alloys and native metals carbides and nitrides were found in mineral separates from bulk rock probes of chromitite and peridotite from tibet polar ural and other localities similar findings of super reduced phases were reported for pyroclastic rocks and alluvial deposits of mt carmel in israel we performed the study of microinclusions in corundum grains from abrasive materials produced industrially in an electric arc furnace and found that they are very similar to microinclusions in corundum grains from natural samples the key similar phases are ti3 4al2 zr ti4 4o11 carmeltazite ti2o3 tistarite tin1 x tic1 x fe si and fe si ti alloys hibonite grossite anorthite and residual feldspatic glass although some differences between abrasive corundum and corundum from tibet and mt carmel are obvious the morphology of melt pockets and amount of mineralogical similarities is more than critical to suggest that they can be of the same origin the additional possible source of corundum grains with super reduced inclusions is various al bearing slags after aluminothermic reactions during steelmaking moreover taking into account the spectacular similarity of diamonds from ophiolite with synthetic diamonds we claim for a thorough reconsideration of ultrahigh pressure and super reduced phases in natural rocks and argue that we need to find criteria for discrimination between natural and artificial samples one of the strongest criteria would be textural and structural features that clearly demonstrate the indigenous character of the host minerals

evidence for local shifting of the main fault and changes in the structural setting kinarot basin dead sea transform two new high resolution seismic reflection profiles from the kinarot valley dead sea rift analyzed with older conventional oil exploration profiles throw light on the quaternary evolution of the african arabian transform type plate boundary in the area the present en echelon main faults of the dead sea transform are observed in the seismic data as wide zones of deformation rather than as distinct fault planes a similar zone of deformation is observed in the center of the kinarot basin and may be associated with an extinct trace of the main fault the zemah structure previously mapped and drilled is shown by the new data to be an inactive anticline compression within the basin is suggested as being the result of motion along the now inactive main fault observed in the center of the basin compression and shortening started some 2 m y ago and ended late in the quaternary as a result of changes in the geometry of the transform at present the kinarot basin is subsiding

discovery of bridgmanite the most abundant mineral in earth in a shocked meteorite meteorites exposed to high pressures and temperatures during impact induced shock often contain minerals whose occurrence and stability normally confine them to the deeper portions of earth s mantle one exception has been mgsio 3 in the perovskite structure which is the most abundant solid phase in earth here we report the discovery of this important phase as a mineral in the tenham l6 chondrite and approved by the international mineralogical association specimen ima 2014 017 mgsio 3 perovskite is now called bridgmanite the associated phase assemblage constrains peak shock conditions to 24 gigapascals and 2300 kelvin the discovery concludes a half century of efforts to find identify and characterize a natural specimen of this important mineral

estimation of the degree of partial melting by na2o k2o and al2o3sio2 of basic magmas abstract equations for estimating the degree of partial melting f of basic magmas in terms of na2o k2o and al 2 o 3 sio 2 and based on previously published batch equilibrium melting and experimental and petrochemical data are proposed as follows for f 0 10 0 50 f a 1 0 957 na 2 o k 2 o s na 2 o k 2 o m 0 0149 for f f b 1 0 694 na 2 o k 2 o s na 2 o k 2 o m 0 0516 for f 0 15 0 35 f c 0 9348 al 2 o 3 sio 2 s al 2 o sio 2 m 0 1532 0 108 al 2 o 3 sio 2 s al 2 o sio 2 m 0 597 for f f d 1 2437 al 2 o 3 sio 2 s al 2 o sio 2 m 0 2470 3 308 al 2 o 3 sio 2 s al 2 o sio 2 m 0 237 the subscripts s and m denote source and supposedly primary magma or melt respectively a correct estimate or choice of source composition and composition of primary magma for the calculation is important if both compositions can be reasonably assigned or estimated then the degree of partial melting can be calculated from one of these equations with errors generally

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

the dead sea rift lateral displacement and downfaulting phases abstract a sinistral strike slip of 105 km along the dead sea rift is confirmed by the continuity in the restored trend of eocene sedimentary belts yet the similar characteristics on either side of the rift between the upper miocene conglomerates mudstones and lithographic limestones particularly the kefar gil adi fm and the pliocene marls oolitic limestones and basalts e g bira fm gesher fm cover basalt raise doubts as to whether a major lateral slip occurred after the end of the upper miocene or even during that epoch the master fault along which motion took place runs through the middle of the jordan valley on the western side of the hula valley through the metulla saddle and the ayoun valley and merges with the yammunneh fault major phases mainly of downfaulting occurred 1 during the middle and at the beginning of the upper miocene hordos fm and post hordos 2 subsequent to deposition during the upper miocene and pliocene and 3 towards the end of the lower pleistocene post ubediye and mishmar hayarden fms when tilting and folding within the rift marked the last significant stage of its formation

structural position of the pleistocene gesher benot ya aqov site in the dead sea rift zone abstract newly discovered outcrops of the middle pleistocene benot ya aqov formation are strongly disturbed due to recent tectonic activity along the dead sea rift the lacustrine fluviatile sediments of this formation comprise the littoral facies of a paleo lake that occupied the adjacent hula basin acheulian artifacts found embedded in the formation have typical african characteristics the geographical position of the site the northern extension of the east african red sea rift system is important for understanding hominid diffusion from africa to eurasia

a review of the geochemistry of methane in natural gas hydrate the largest accumulations on earth of natural gas are in the form of gas hydrate found mainly offshore in outer continental margin sediment and to a lesser extent in polar regions commonly associated with permafrost measurements of hydrocarbon gas compositions and of carbon isotopic compositions of methane from natural gas hydrate samples collected in subaquatic settings from around the world suggest that methane guest molecules in the water clathrate structures are mainly derived by the microbial reduction of co2 from sedimentary organic matter typically these hydrocarbon gases are composed of 99 methane with carbon isotopic compositions 13cpdb ranging from 57 to 73 in only two regions the gulf of mexico and the caspian sea has mainly thermogenic methane been found in gas hydrate there hydrocarbon gases have methane contents ranging from 21 to 97 with 13c values ranging from 29 to 57 at a few locations where the gas hydrate contains a mixture of microbial and thermal methane microbial methane is always dominant continental gas hydrate identified in alaska and russia also has hydrocarbon gases composed of 99 methane with carbon isotopic compositions ranging from 41 to 49 these gas hydrate deposits also contain a mixture of microbial and thermal methane with thermal methane likely to be dominant published by elsevier science ltd

seismic reflection across a continental transform an example from a convergent segment of the dead sea rift three seismic reflection lines in the dead sea rift in northern israel cross the transform plate boundary between arabia and the sinai block of the african plate the arabian plate edge consists of the meshoshim tilted block which we suggest to be partly a result of prerift activity in the sinai block the elevated rosh pinna saddle is faulted over the meshoshim block with a vertical separation of 2 5 3 km much of this separation is due to young reverse faulting which is related to the oblique plate boundary in this area the main fault zone transfers the motion from the western margin of the kinneret zemah graben to the eastern margin of the hula graben immediately north of lake kinneret the main fault is a 1 to 2 km wide zone of extensive deformation and a discrete main fault trace is hard to define further to the north the deformation is less extensive and is concentrated in a narrow fault zone deformation across the plate boundary is asymmetrical and while the meshoshim block is quite coherent the rosh pinna saddle is a highly faulted and deformed positive flower structure

stress tensor and focal mechanisms along the dead sea fault and related structural elements based on seismological data the dead sea fault is among the largest active strike slip fault of the world this study is focused on the southern part of this fault from the sea of galilee to the gulf of aqaba as monitored mainly by the jordanian and israeli seismic networks the data of arrival times and polarities allowed relocation of earthquakes with a better azimuthal coverage and computation of focal mechanisms this last step has been realized by inverting the polarities to determine a unique stress tensor for the region and the compatible focal mechanisms inversion with different subsets of the data set based on tectonic regionalization has also been performed to evaluate the impact of each cluster of earthquakes on the global solution the population of focal mechanisms is clearly dominated by strike slip events with the notable exception of a cluster of earthquakes south of the dead sea which displays several normal focal mechanisms this last cluster forces 1 to be vertical and 2 to be horizontal a large number of fault planes however are close to the vertical inhibiting the action of the vertical component of the stress tensor and acting like under strike slip stress regime we observed a good agreement between the location of the earthquakes and the active faults based on geological data in addition there is a good agreement between the fault plane solutions and the orientation of the active faults

probabilistic seismic hazard assessment for the arabian peninsula a seismic hazard evaluation in terms of 5 damped peak ground acceleration and spectral acceleration was carried out for the arabian peninsula using a probabilistic approach for this purpose a revised earthquake catalogue extending from 19 ad to 2015 ad was utilized including all available earthquakes with magnitude greater than 4 0 the seismic hazard assessment was conducted in the framework of the logic tree approach to take into account epistemic uncertainties associated with input parameters seismic source model recurrence parameters maximum magnitude and ground motion prediction equations gmpes a novel seismic source model consisting of 57 seismic zones is proposed as an alternative included in the modeled logic tree the recurrence parameters were computed mainly using the doubly bounded exponential distribution horizontal ground motion in terms of geometric mean acceleration was computed for different spectral periods utilizing gmpes borrowed from tectonic environments comparable to those surrounding the arabian peninsula the 5 damped seismic hazard values at bedrock conditions were calculated for return periods of 475 975 and 2475 years additionally uniform hazard spectra for important population centers in the arabian peninsula are provided the highest seismic hazard values were observed along the zagros the east anatolian fault and the gulf of aqaba dead sea fault the provided maps could be used to design the unified gulf building code

anatomy of landslides along the dead sea transform fault system in nw jordan abstract in the mountainous region north of amman jordan cenomanian calcareous rocks are being monitored constantly for their mass wasting processes which occasionally cause severe damage to the amman irbid highway satellite remote sensing data landsat tm aster and srtm and ground measurements are applied to investigate the anatomy of landslides along the dead sea transform fault system dstfs a prominent strike slip fault the joints and faults pertinent to the dstfs match the architectural elements identified in landslides of different size this similarity attests to a close genetic relation between the tectonic setting of one of the most prominent fault zones on the earth and modern geomorphologic processes six indicators stand out in particular 1 the fractures developing in n s and splay faults represent the n s lateral movement of the dstfs they governed the position of the landslides 2 cracks and faults aligned in ne sw to nnw ssw were caused by compressional strength they were subsequently reactivated during extensional processes and used in some cases as slip planes during mass wasting 3 minor landslides with ne sw straight scarps were derived from compressional features which were turned into slip planes during the incipient stages of mass wasting they occur mainly along the slopes in small wadis or where a wide wadi narrows upstream 4 major landslides with curved instead of straight scarps and rotational slides are representative of a more advanced level of mass wasting these areas have to be marked in the maps and during land management projects as high risk area mainly and may be encountered in large wadis with steep slopes or longitudinal slopes undercut by road construction works 5 the spatial relation between minor faults and slope angle is crucial as to the vulnerability of the areas in terms of mass wasting 6 springs lined up along faults cause serious problems to engineering geology in that they step up the behavior of marly interbeds to accelerate sliding during mass wasting the most vulnerable areas prone to slope instabilities are those with compressional tectonics followed by extensional movements with fault bound springs and smectite bearing marly layers interbedded with pure massive limestones the semi arid to arid climate with periodic rainfalls combined with subsurface water circulation along the joints and faults can trigger mass wasting

faults landslides and seismic hazards along the jordan river gorge northern israel abstract faults and adjacent seismotectonically controlled landslides forming a specific morphotectonic junction were mapped along the jordan river gorge between the hula and sea of galilee depressions and the almagor area the morphotectonic junction and its structural features reflect the existence of a major fault along the bottom of the jordan river gorge where a probable transform fault was previously inferred by regional platetectonic studies this morphotectonic junction is interpreted to be the epicentre area of strong earthquakes within the northern jordan rift valley the last of these probably occurred in 1837 zefat earthquake with a local ground acceleration of the order of 0 5 0 7 g

fault geometry and spatial clustering of microearthquakes along the dead sea jordan rift fault zone abstract earthquakes 1 0 m l 5 3 in the region around the dead sea jordan rift fault zone recorded by the israel scismograph station network issn from 1982 until the beginning of 1989 have been analyzed and interpreted the scismicity pattern clearly reveals activity along three fault zones the dead sea jordan rift fault zone the carmel faraa fault zone and the central sinai negev shear zone microearthquake occurrence tends to cluster in or near tensional features rhomb shaped grabens such as the hula sea of gallilee and dead sea depressions further eight representative focal mechanisms of individual earthquakes or earthquake clusters have been derived the seismicity and focal mechanism solutions near the branching of the carmel faraa and the dead sea jordan rift fault zones suggest a complicated tectonic breakup in this region microearthquakes in the arava may indicate a more complex pattern of active faults than was previously assumed

origin of archean ferropicrites geochemical constraints from the boston creek flow abitibi greenstone belt ontario canada abstract new major element trace element and nd isotope data for non cumulate samples from the fe enriched boston creek flow bcf have permitted the development of a petrogenetic model for the origin of this geochemically unusual flow the data reveal high contents of nb ta lree ti ni co and ir as well as in fe and low contents of al al 2 o 3 tio 2 6 hree y v sc pd and pt compared to komatiitic rocks and typical tholeiitic rocks of similar magnesian content primitive mantlenormalized incompatible trace element profiles for the bcf peak in the ta nb la region la sm n 2 0 la yb n 5 4 th ta n 0 7 and bottom in the al sc region la sc n 11 0 la al n 9 7 and reveal slight depletions in zr and hf relative to mree sm zr n 1 3 and ti nd t 2720 ma values for the flow are 2 5 indicating derivation of the parental melt from a long term depleted mantle source these geochemical characteristics are somewhat similar to those of modern oceanic within plate basalts these unusual geochemical characteristics and comparisons to proterozoic ferropicrite flows at pechenga russia indicate that the bcf is ferropicritic rather than komatiitic in affinity alteration assimilation and magma mixing and crystal fractionation processes cannot explain the bcf therefore the distinctive geochemistry of the bcf is concluded to have been a feature of its mantle source and is attributed to mantle processes models involving melting of core material in the mantle source may explain the enrichment of fe and high ni in the bcf but they are contradicted by the relatively low pt and pd models involving olivine equilibration in the mantle are consistent with the high ni and co similar composition of assumed bcf parental melt equilibrium olivine at 25 kbar and that of modern fe rich lherzolite olivine fo85 and comparison of the mgo and feo content of the melt with those of experimentally derived melts that are saturated in olivine at high pressure models involving garnet equilibration in the mantle could explain the low al hree y v and sc but are contradicted by the very low al2o3 content of the assumed parental melt compared with those of experimentally derived melts of similar feo and mgo content that are saturated in garnet at high pressure alternatively the unusual geochemistry of the bcf can be explained by a two source component mixing model somewhat like those commonly accepted for oceanic within plate basalts petrogenesis the first source component is peridotite depleted by extraction of melt s prior to generation of the bcf parental melt which explains the relatively high compatible element contents and low al hree sc pd and pt contents the second source component is highly enriched small degree melt fractions formed at mantle depths sufficient to stabilize garnet majorite which explains the relative enrichments in fe ti and the highly incompatible elements mixing of the two source components must have occurred immediately prior to melting to maintain the depleted nd isotope composition and may have been facilitated by metasomatic amphibole stabilization at relatively shallow 100 km depths in the mantle

a petrologic model for the constitution of the upper mantle and crust of the koolau shield oahu hawaii and hawaiian magmatism abstract a petrological model for the uppermost upper mantle and crust under the koolau shield to a depth of about 60 km has been derived on the basis of petrology of the upper mantle and crustal xenoliths in nephelinites of the honolulu volcanic series three main xenolith suites exist in the koolau shield dunites spinel lherzolites and garnet bearing pyroxenites on the basis of mineralogy it is inferred that the dunites represent cumulates in shallow crustal tholeiitic magma chambers the spinel lherzolites form a thick 40 km layer in the upper mantle and the garnet pyroxenite suite occurs as veins and stringers in the spinel lherzolites at about 60 km depth the eruption sequence in a hawaiian volcano i e tholeiite transitional basalt alkali basalt is generated by partial melting of a volatile bearing garnet lherzolite part of a lithospheric plate as it rides over a hot spot if the tholeiite transitional and alkali basalts of hawaiian volcanoes are generated at the same depth then the observed sequence of lavas requires replenishment of the source area with volatiles and gradual decrease of the degree of partial melting with time post erosional olivine nephelinites are produced from isotopically distinct deeper source area which may be the asthenosphere

a mechanism for the formation of methane hydrate and seafloor bottom simulating reflectors by vertical fluid expulsion bottom simulating reflectors bsr are observed commonly at a depth of several hundred meters below the seafloor in continental margin sedimentary sections that have undergone recent tectonic consolidation or rapid accumulation they are believed to correspond to the deepest level at which methane hydrate clathrate is stable we present a model in which bsr hydrate layers are formed through the removal of methane from upward moving pore fluids as they pass into the hydrate stability field in this model most of the methane is generated below the level of hydrate stability but not at depths sufficient for significant thermogenic production the methane is primarily biogenic in origin the model requires either a mechanism to remove dissolved methane from the pore fluids or disseminated free gas carried upward with the pore fluid the model accounts for the evidence that the hydrate is concentrated in a layer at the base of the stability field for the source of the large amount of methane contained in the hydrate and for bsrs being common only in special environments strong upward fluid expulsion into the hydrate stability field does not occur in normal sediment depositional regimes so bsrs are uncommon upward fluid expulsion does occur as a result of tectonic thickening and loading in subduction zone accretionary wedges and in areas where rapid deposition results in initial undercconsolidation in these areas hydrate bsrs are common the most poorly quantified aspect of the model is the efficiency with which methane is removed and hydrate is formed as pore fluids pass into the hydrate stability field the critical boundary in the phase diagram between the fluid plus hydrate and fluid only fields is not well constrained however the amount of methane required to form the hydrate and limited data on methane concentrations in pore fluids from deep sea boreholes suggest very efficient removal of methane from rising fluid that may contain less than the amount required for free gas production in most fluid expulsion regimes the quantity of fluid moved upward to the seafloor is great enough to continually remove the excess chloride and the residue of isotope fractionation resulting from hydrate formation thus as observed in borehole data there are no large chloride or isotope anomalies remaining in the local pore fluids the differences in the concentration of methane and probably of co2 in the pore fluid above and below the base of the stability field may have a significant influence on early sediment diagenetic reactions

young faults in the hula pull apart basin central dead sea transform abstract the geometry and nature of structural features inside the hula pull apart basin at the central dead sea transform are presented here two systems of n s left lateral strike slip faults are located on the east and west sides of the hula basin both fault systems are composed of several segments arranged in a right stepping en echelon pattern the northern end of each segment is bent northeastward and usually merges with the next segment elevated regions and small hills appear on the northern side of each bend the strike slip faults are oblique with both vertical and horizontal components the vertical component may be normal or reverse although the hula valley is subjected to general extension the studied structures indicate local compression inside the basin normal faults striking e w comprise the northern border of the hula basin age determination of displaced travertines and basalts along the faults indicates sub recent tectonic activity and suggests migration of normal faulting towards the inner part of the basin the youngest fault displaces travertine dated at 25 300 years

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

structural geometry and evolution of the dead sea jordan rift system as deduced from new subsurface data abstract analysis of deep drilling data and seismic reflection surveys obtained in recent years permit establishment of a tectonic model of the dead sea jordan rift system that is in part conformable with some of the many often controversial theories on this subject but which also introduces new information negating some concepts that are widely accepted in the literature the dead sea jordan rift system is not a tensional graben between two parallel sets of faults but instead can be best defined as a sinistral transform connecting an incipient oceanic ridge the red sea with an upthrusted collision zone the taurus range the shear is caused by the opening of the red sea and the motion of the arabian sub plate away from the african plate the shearing occurs along a largely south north trending slightly arcuate une consisting of a series of en echelon left stepping left lateral strike slip master faults of varying lengths these faults characteristically die out to the north by bending outward northeast and the movement is taken up by the strike slip faults to the left i e to the west where overlap of the two faults occurs very narrow and very deep grabens have evolved in places the width being equal to the depth the narrowness of these grabens is dictated by the closeness of the overlapping segments of the successive strike slip faults this feature points to the probability that the en echelon strike slip faults have a common root zone at great depth these grabens are not typical leaky pull aparts in that they have no gravimetric magnetic or heat flow anomalies nor are they closed on all four sides by large faults their northern ends are characterized by gradually rising graben floors without major diagonal cross faults the dead sea jordan rift system sensu stricto extends over a distance of 420 km from the northern shore of the gulf of elat to the northern margin of the hula valley southward it is connected with the red sea along the gulf of elat transition zone which has elements of strike slip as well as tensional opening a northern transition zone exists between the hula valley and the taurus arc where diminishing strike slip movement is compensated by several underthrust belts the time of the beginning of the movement along the rift can be established as pre middle miocene because mid miocene sediments overlie an upper cretaceous graben floor rifting has continued intermittently to the present volcanism in the northern fifth of the rift is genetically associated with the seismically active tensional golan hauran jebel drouz wadi sirhan tectonic trend which has a north west southeast orientation and not with the north south trending dead sea jordan rift

a comparison of the eastern and western sides of the sea of galilee and its implication on the tectonics of the northern jordan rift valley abstract the sea of galilee divides two neogene basins which are characterized by largely continental clastic sequences and basalt flows stratigraphic differences between the two basins are discerned a comparison of the stratigraphy of both sides of the sea of galilee does not support the postulated 107 km left lateral movement although some small strike slip faults might exist most faults are of a gravity dip slip type a postulated ridge trending nne buried under the sea of galilee might have had a stratigraphic influence on sediment distribution between the eastern and western sides

hutcheonite ca3ti2 sial2 o12 a new garnet mineral from the allende meteorite an alteration phase in a ca al rich inclusion hutcheonite ima 2013 029 ca 3ti 2 sial 2 o 12 is a new garnet mineral that occurs with monticellite grossular and wadalite in secondary alteration areas along some cracks between primary melilite spinel and ti al diopside in a type b1 fractionation and unidentified nuclear effects fun ca al rich inclusion cai egg 3 from the allende cv vigarano type carbonaceous chondrite the mean chemical composition of type hutcheonite by electron probe microanalysis is wt cao 34 6 tio 2 25 3 sio 2 20 9 al 2o 3 15 7 mgo 2 1 feo 0 7 v 2o 3 0 5 total 99 8 giving rise to an empirical formula of ca 2 99 ti 4 1 53 mg 0 25 al 0 17 fe 2 0 05 v 3 0 03 si 1 68 al 1 32 o 12 the end member formula is ca 3ti 2 sial 2 o 12 hutcheonite has the ia3d garnet structure with a 11 843 a v 1661 06 a 3 and z 8 as revealed by electron backscatter diffraction the calculated density using the measured composition is 3 86 g cm 3 hutcheonite is a new secondary phase in allende apparently formed by iron alkali halogen metasomatic alteration of the primary cai phases like melilite perovskite and ti al diopside on the cv chondrite parent asteroid formation of the secondary ti rich minerals like hutcheonite during the metasomatic alteration of the allende cais suggests some mobility of ti during the alteration the mineral name is in honor of ian d hutcheon a cosmochemist at lawrence livermore national laboratory california u s a

leaching of lisan marl and its consequences on the engineering behavior of dikes studied by finite elements modeling leaching of lisan marl dead sea jordan increased the soil compressibility and cohesion intercept back analysis using the plaxis finite element code was successfully implemented the finite element modeling of dike construction showed a significant increase of total settlement and negligible effect on the strength as calculated by the c reduction method the height of dikes to be constructed on lisan marl as foundation material should be optimized to account for the effect of soluble salts leaching for this to take place an accurate calculation of settlement is crucial

the petrology of some picrites from mauna loa and kilauea volcanoes hawaii the mineralogy and chemistry of picrites from mauna loa and kilauea have been investigated to evaluate for hawaiian tholeiitic picrites the contrasting genetic models which have been proposed for these mg rich volcanics namely products of direct crystallization of high mg melts 20 25 mgo or the result of accumulation of olivine phenocrysts into less mg rich melts genetic interpretations rely heavily on mg fe partitioning relations between olivines and their picrite hosts although the 100 mg mg fe2 ratios m of picrites are wide ranging m 73 6 82 9 for fe2o3 feo 0 15 with mgo as high as 27 8 the average 100 mg mg fe ratios mg of the cores of olivine phenocrysts megacrysts show only restricted compositional variation mg 87 2 89 0 successive olivine generations are progressively more fe rich olivine liquid mg fe partitioning data and the mn and ni abundances in olivine phenocrysts collectively indicate that they were precipitated by mg rich basaltic melts with 12 14 mgo spinel compositions range from liquidus magnesiochromites occurring mainly as inclusions in olivine phenocrysts to groundmass titanomagnetites which crystallized at nearsolidus temperatures the cr2o3 contents and m values of liquidus magnesiochromites suggest that their parent melts were neither mg rich picritic mgo 20 nor relatively mg poor basaltic types