petrology and textural classification of the jericho kimberlite northern slave province nunavut canada the paper presents data on petrology bulk rock and mineral compositions and textural classification of the middle jurassic jericho kimberlite slave craton canada the kimberlite was emplaced as three steep sided pipes in granite that was overlain by limestones and minor soft sediments the pipes are infilled with hypabyssal and pyroclastic kimberlites and connected to a satellite pipe by a dyke the jericho kimberlite is classified as a group ia lacking groundmass tetraferriphlogopite and containing monticellite pseudomorphs the kimberlite formed during several consecutive emplacement events of compositionally different batches of kimberlite magma core logging and thin section observations identified at least two phases of hypabyssal kimberlites and three phases of pyroclastic kimberlites hypabyssal kimberlites intruded as a main dyke hk1 and as late small volume aphanitic and vesicular dykes massive pyroclastic kimberlite mpk1 predominantly filled the northern and southern lobes of the pipe

low temperature exsolution in refractory siderophile element rich opaque assemblages from the leoville carbonaceous chondrite abstract a model for the formation of opaque assemblages in refractory inclusions in c3v chondrites was proposed by blum et al 1 2 in which the assemblages formed not by direct condensation but by crystallization from siderophile element rich droplets within molten silicate inclusions followed by low temperature exsolution and oxidation and or sulfidation although the data presented do not address the high temperature histories of these objects we describle herein two opaque assemblages in a leoville refractory inclusion which provide the strongest textural and chemical evidence yet found in natural samples for the relatively low temperature equilibration called for in this model the assemblages have fine fe in ni fe with sharp contacts between phases the larger 35 35 m of the two assemblages oa1 has sets of regularly spaced parallel lamellae demonstrating crystallographic control in the other oa2 ir and pt partitioning between lamellae and host is consistent with equilibration at 873 k as are the fe ni and ru contents of coexisting eru fe and ni fe and the narrow widths of the lamellae in both assemblages the bulk compositions of the two assemblages bracket a previously inferred phase boundary in the fe ni ru system at 873 k in these assemblages the observed phases and their compositions are as predicted by the inferred phase relations at this temperature suggesting that the position of the inferred phase boundary is correct this is the same equilibration temperature estimated by blum et al 2 for another opaque assemblage from leoville also on the basis of alloy compositions and inferred phase equilibria in the fe ni ru system the similarity of results for different leoville samples is consistent with the suggestion 2 that final equilibration of the assemblages was post accretionary

criteria for interpreting kimberlite as coherent insights from the muskox and jericho kimberlites nunavut canada the jurassic muskox and jericho kimberlites northern slave province nunavut canada contain a variety of facies exhibiting different geometries contact relationships internal organisation country rock abundance and olivine shapes although many have similar matrix groundmass mineralogies and textures five facies are examined that either have characteristics consistent with coherent rocks in general i e intrusive and extrusive non fragmental rocks or are mineralogically and texturally similar to kimberlite described as coherent or apparent coherent three facies are interpreted as coherent on the basis of 1 geological setting 2 apparent porphyritic texture 3 sharp contacts with fragmental kimberlite 4 relative abundance of elongate and unbroken olivine crystals and 5 paucity of country rock xenoliths while the remaining two facies are interpreted as fragmental on the basis of 1 the gradational contacts with demonstrably fragmental kimberlite 2 relative abundance and range of sizes of country rock lithic clasts and 3 numerous broken olivine crystals comparisons are made with coherent and apparent coherent kimberlite from the literature our three coherent facies are similar to literature reported coherent kimberlite dykes hosted in country rock ckd in terms of internal organisation low abundance of country rock xenoliths and apparent porphyritic texture conversely our two fragmental facies share attributes with previously described pipe filling coherent and apparent coherent kimberlite ckpf in terms of geometry internal organisation and abundance of country rock xenoliths we conclude that ckd and most ckpf although similar in matrix groundmass mineralogy and texture can be distinguished on the basis of internal organisation country rock lithic clast abundance texture e g apparent porphyritic texture and possibly olivine crystal shapes and suggest that fragmental kimberlite is more common than reported

reconstruction of a multi vent kimberlite eruption from deposit and host rock characteristics jericho kimberlite nunavut canada abstract the jericho kimberlite 173 1 1 3 ma is a small 130 70 m multi vent system that preserves products from deep 1 km portions of kimberlite vents pit mapping drill core examination petrographic study image analysis of olivine crystals grain size distributions and shape studies and compositional and mineralogical studies are used to reconstruct processes from near surface magma ascent to kimberlite emplacement and alteration the jericho kimberlite formed by multiple eruptions through an archean granodiorite batholith that was overlain by mid devonian limestones 1 km in thickness kimberlite magma ascended through granodiorite basement by dyke propagation but ascended through limestone at least in part by locally brecciating the host rocks after the first explosive breakthrough to surface vent deepening and widening occurred by the erosive forces of the waxing phase of the eruption by gravitationally induced failures as portions of the vent margins slid into the vent and in the deeper portions of the vent 1 km by scaling as thin slabs burst from the walls into the vent at currently exposed levels coherent kimberlite ck dykes

parental carbonatitic melt of the koala kimberlite canada constraints from melt inclusions in olivine and cr spinel and groundmass carbonate abstract this study of the hypabyssal kimberlite with particularly fresh olivine from the palaeogene koala pipe ekati cluster slave craton canada is focused on reconstruction of the kimberlite parental melt the koala kimberlite sample is a typical ultramafic rock archetypal or group i kimberlite containing large abundance of forsteritic olivine set in a carbonate rich matrix the euhedral olivine ii shows significant zoning in terms of forsterite content and trace elements only the rims of olivine ii are considered to be magmatic they are uniform in terms of fo 91 5 0 2 mol and host primary crystal apatite cr spinel and melt inclusions the magmatic spinel phenocrysts are strongly zoned from titanian magnesian chromite to pleonaste with the cores having the same composition as spinel inclusions in olivine the primary and pseudo secondary melt inclusions in both magmatic cr spinel and olivine comprise a complex assemblage of daughter phases dominated by carbonate minerals dolomite eitelite na 2 mg co 3 2 shortite na 2 ca 2 co 3 3 nyerereite na 2 ca co 3 2 zemkorite na k 2 ca co 3 2 and fairchildite k 2 ca co 3 2 in addition to the dominant carbonates the melt inclusions contain phosphates chlorides and sulphates bradleyite na 3 mg po 4 co 3 halite sylvite aphthitalite na 0 25 k 0 75 2 so 4 but the silicate component is represented by tetraferriphlogopite only the melt inclusions in olivine studied in heating experiments show immiscibility of two carbonate liquids on heating and cooling and homogenise at low temperature 2 o sro and bao in wt 0 37 0 65 1 17 2 40 2 37 4 18 respectively such compositions are compared to secondary calcite replacing nyerereite and shortite in the natrocarbonatite lavas of the modern oldoinyo lengai volcano the results on mineralogy composition and homogenisation temperature of melt inclusions and the groundmass of the koala kimberlite imply that the parental kimberlite liquid was a si poor ca mg carbonate enriched in alkali elements lithophile trace elements phosphorus chlorine and sulphur

domestic origin of opaque assemblages in refractory inclusions in meteorites experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium and aluminium rich inclusions cais by exsolution oxidation and sulphidization of homogeneous alloys rather than by aggregation of materials in the solar nebula before the formation of cais these opaque assemblages are thus not the oldest known solid materials as was once thought and they do not constrain processes in the early solar nebula before cai formation instead the assemblages record the changing oxygen fugacity experienced by cais during slow cooling in nebular and or planetary environments

evidence for extraneous origin of a magnesiowustite metal fremdling from the vigarano cv3 chondrite a calcium aluminum rich inclusion cai from the vigarano cv3 chondrite 477b contains three types of fremdlinge and pt rich phases 1 feni blebs 2 sub micron pt rich fe bearing nuggets and 3 pt rich fe bearing veins many of the feni fremdlinge contain grains of mgfe oxide periclase wustite series ion microprobe measurements of an unusually large 5 m per70 wu30 grain reveal isotopically light mg 4 3 amu in contrast to heavy mg 4 7 amu in adjacent spinel and melilite the oxygen isotopic composition of the periclase wustite is 17osmow 9 1 18osmow 12 5 distinct from isotopically normal oxygen in the surrounding melilite and the large 16o enrichments 16oexcess 52 in adjacent spinel the petrographic mineral chemical and isotopic properties of the magnesiowustite grain argue against in situ formation in the cai and indicate an extraneous origin from a reservoir depleted in silicon this reservoir probably had normal oxygen in contrast to the 16o rich reservoir from which the cai formed and isotopically light magnesium

velocity probability density functions for oceanic floats probability density functions pdfs of daily velocities from subsurface floats deployed in the north atlantic and equatorial atlantic oceans are examined in general the pdfs are approximately gaussian for small velocities but with significant exponential tails for large velocities correspondingly the kurtoses of the distributions are greater than three similar pdfs are found in both western and eastern regions above and below 1000 m depth with more significant non gaussianity in the north atlantic than at the equator analogously lagrangian statistics in decaying two dimensional turbulence also display non gaussian velocity pdfs with approximately exponential tails in the limit of large reynolds number

ultrafresh salty kimberlite of the udachnaya east pipe yakutia russia a petrological oddity or fortuitous discovery an ultrabasic ultramafic composition of kimberlite magmas is difficult to reconcile with existing models of the kimberlite mantle source and melting conditions inferred magma temperatures and rheological properties and the style of magma ascent and emplacement the inconsistencies in current thinking indicate serious flaws in understanding kimberlite magma compositions much of the uncertainty over true kimberlite compositions may stem from almost ubiquitous hydration and leaching of kimberlite rocks this study presents petrographic and geochemical data for kimberlite samples largely unaffected by postmagmatic modification from the devonian udachnaya east pipe in siberia these samples are unusually enriched in chlorine and sodium yet they are essentially anhydrous these features are consistent with the phase composition of the groundmass which is dominated by minerals such as na ca carbonates na k chlorides and sulphates which appear to be in our samples co magmatic with common silicates and oxides but are unknown in other kimberlites or rarely found within magmatic assemblages we suggest that a kimberlite parent melt of essentially non silicate composition with high concentrations of alkalis co2 and cl may be a viable alternative to the currently favoured water rich high mg model primary melt entrainment of mantle silicates into such a melt en route to the surface followed by gravitational accumulation of mantle olivine and liquidus oxides perovskite cr spinel at the bottom of vertically extensive magma bodies after emplacement would explain the observed properties of kimberlite magma rock notably enrichment in olivine and trace elements in the hypabyssal kimberlite facies a carbonate melt composition would retain attributes of the standard model such as trace element enrichment via low degrees of partial melting it would explain low temperatures of crystallisation and the exceptional rheological properties that enable kimberlite primary melts to segregate from the lithospheric source and buoyantly ascend at high speed while mixing and reacting with country rocks

the origin of salts in unaltered kimberlites comment on was crustal contamination involved in the formation of the serpentine free udachnaya east kimberlite new insights into parental melts liquidus assemblage and effects of alteration by abersteiner et al 2018 journal of petrology 59 1467 1492

the origin of high hydrogen content in kimberlitic olivine evidence from hydroxyl zonation in olivine from kimberlites and mantle xenoliths abstract olivine macrocrysts in kimberlites are the most h rich natural olivines known their xenocrystic provenance makes unclear whether h enrichment occurred in the mantle prior to entrainment in kimberlite magma or during ascent we present a fourier transform infrared ftir spectroscopy based study of h zonation in kimberlite derived olivine macrocrysts and or olivine in xenoliths from the kimberlites jericho nunavut canada beartooth northwest territories canada and pipe 200 and matsoku lesotho the objective of the study was to determine whether changes in the concentration or speciation of h defects in proximity to the host kimberlite could yield insights into the origin of h enrichment within the group 1 region of the ftir spectrum 3420 3700 cm 1 we find that olivines within xenoliths and macrocrysts show weak zonation or significant h depletions in rims peaks in the group 2 region 3260 3420 cm 1 in beartooth olivines show marked decrease in the crystal margins in comparison to group 1 peaks we find no preserved evidence for kimberlite related h enrichment in our dataset we ascribe h depletion to diffusive h loss to infiltrating kimberlitic media diffusion models using coefficients previously applied to dehydrogenation of olivine and assuming a dry environment produce extremely short ascent durations incompatible with the results of other geospeedometers this mismatch suggests that the poorly developed zonation in jericho and beartooth olivines indicates water enrichment and or faster ascent of these melts in comparison to pipe 200 and matsoku resulting in greater retention of mantle derived h a further significant factor in the mismatch is the differing speciation of h in most natural mantle derived olivines in comparison to those used in diffusion experiments we argue that the presence of presumably mantle derived group 2 h in olivine macrocrysts indicates rapid ascent of magma exsolving water rich fluid permitting preservation of these faster diffusing defects only in particularly rapidly ascending kimberlite magmas this interpretation explains empirical correlations between the presence of group 2 bands water derived diamond resorption features and volcaniclastic kimberlite facies

petrology of hypabyssal kimberlites relevance to primary magma compositions abstract hypabyssal kimberlites are similar in their mineralogy and geochemistry across the world and thus form a distinct magma type that is produced repeatedly in time and space this small volume magma is derived from the asthenosphere 200 650 km and as it nears the surface consists of olivine macrocrysts i e xenocrysts 25 vol olivine phenocrysts 25 vol entrained in a ba ti mg rich al poor carbonate silicate liquid containing high but unknown amounts of dissolved co2 ch4 and h2o hypabyssal kimberlites are shown to be hybrid rocks formed by mixing with and assimilation of mantle derived lherzolite and harzburgite orthopyroxene is not stable in these magmas and its resorption leads the precipitation of primary liquidus olivine the magma crystallizes rapidly at crustal levels to uniform holocrystalline rocks that do not contain glass in addition to spinel perovskite monticellite apatite and phlogopite kinoshitalite primary carbonates are typically present as low pressure liquidus phases serpentines primary polygonal serpentine and chrysotile and carbonate commonly crystallize together from volatile rich co2 h2o deuteric residua as a polycrystalline mesostasis or discrete segregations the latter are not in filled vesicles kimberlite magmas have a very long crystallization interval ranging from 1200 to 300 c and there is a continuum from the magmatic crystallization of silicate and oxide minerals to carbo hydrothermal residua forming the calcite serpentine mesostasis it is concluded that there are no hypabyssal kimberlites which are representatives of the initial primary magma all kimberlites are hybrid and contaminated magmas which have undergone crystallization in the mantle prior to crystallization of the groundmass mesostasis assemblages

polymineralic inclusions in kimberlite hosted megacrysts implications for kimberlite melt evolution abstract megacrysts are large cm to 20 cm in size mantle derived crystals which are commonly entrained by kimberlite magmas comprising of olivine orthopyroxene clinopyroxene phlogopite garnet ilmenite and zircon as common phases numerous studies have shown megacrysts to contain polymineralic inclusions which have been interpreted to represent entrapped kimberlite melt to constrain the origin of these inclusions in megacrysts and their relationship to kimberlite magmatism we present a detailed petrographic and geochemical study of clinopyroxene and olivine megacrysts and their hosted inclusions from the diavik jericho leslie slave craton canada and udachnaya east siberian craton russia kimberlites the studied megacrysts are between 1 and 3 cm in size and representative of both the cr rich and cr poor suites megacrysts contain two types of inclusions i large ii swarms trails of micro melt inclusions mmi textural and geochemical evidence suggests that polymineralic inclusions in megacrysts crystallised from kimberlite melt which infiltrated along fracture vein networks the polymineralic inclusion assemblages resulted from disequilibria reactions between the host megacryst and infiltrating kimberlite melt which was likely enhanced by rapidly changing conditions during magmatic ascent the connectivity of polymineralic inclusions to the kimberlite groundmass via network veins fractures suggests that they are susceptible to infiltrating post emplacement fluids therefore the vast majority of polymineralic inclusions are unlikely to represent pristine entrapped kimberlite melt in contrast mmis are isolated within megacrysts i e not connected to fractures veins and therefore shielded from post magmatic fluids and probably represent entrapped remnants of the variably differentiated kimberlite melt which was more enriched in alkalis cl s co2 than serpentinised polymineralic inclusions and the host rocks exposed at earth s surface as kimberlites

sedimentologic and stratigraphic constraints on emplacement of the star kimberlite east central saskatchewan abstract diamond bearing kimberlites in the fort a la corne region east central saskatchewan consist primarily of extra crater pyroclastic deposits which are interstratified with lower cretaceous albian and cenomanian marine marginal marine and continental sediments approximately 70 individual kimberlite occurrences have been documented the star kimberlite occurring at the southeastern end of the main fort a la corne trend has been identified as being of economic interest and is characterized by an excellent drill core database integration of multi disciplinary data sets has helped to refine and resolve models for emplacement of the star kimberlite detailed core logging has provided the foundation for sedimentological and volcanological studies and for construction of a regionally consistent stratigraphic and architectural framework for the kimberlite complex micropaleontologic and biostratigraphic analysis of selected sedimentary rocks and u pb perovskite geochronology on kimberlite samples have been integrated to define periods of kimberlite emplacement radiometric age determination and micropaleontologic evidence support the hypothesis that multiple kimberlite eruptive phases occurred at star the oldest kimberlite in the star body erupted during deposition of the predominantly continental strata of the lower mannville group cantuar formation kimberlites within the cantuar formation include terrestrial airfall deposits as well as fluvially transported kimberlitic sandstone and conglomerate successive eruptive events occurred contemporaneous with deposition of the marginal marine upper mannville group pense formation kimberlites within the pense formation consist primarily of terrestrial airfall deposits fine to medium grained cross stratified kimberlitic olivine dominated sandstone in this interval reflects reworking of airfall deposits during a regional marine transgression the location of the source feeder vents of the cantuar and pense kimberlite deposits has not been identified the youngest and volumetrically most significant eruptive events associated with the star kimberlite occur within the predominantly marine lower colorado group joli fou and viking formations kimberlite beds which occur at several horizons within these units consist of subaerial and marine fall deposits the latter commonly exhibiting evidence of wave reworking black shale encased resedimented kimberlite beds likely deposited as subaqueous debris flows and turbidites are particularly common in the lower colorado group during its multi eruptive history the star kimberlite body is interpreted to have evolved from a feeder vent and overlying positive relief tephra ring into a tephra cone initial early joli fou volcanism resulted in formation of a feeder vent 200 m diameter and tephra ring subsequent eruptions dominated by subaerial deposits partly infilled the crater and constructed a tephra cone a late joli fou eruption formed a small 70 m diameter feeder pipe slightly offset to the nw of the early joli fou feeder vent deposits from this event further infilled the crater and were deposited on top of early joli fou kimberlite proximal to the vent and sediments of the joli fou formation distal to the vent the shape of the tephra cone was modified during multiple marine transgression and regression cycles coeval with deposition of the lower colorado group resulting in wave reworked kimberlite sand along the fringes of the cone and kimberlitic event deposits tempestites turbidites debris flows in more distal settings

distinct kimberlite pipe classes with contrasting eruption processes abstract field and scott smith field m scott smith b h 1999 contrasting geology and near surface emplacement of kimberlite pipes in southern africa and canada proc 7th int kimb conf eds gurney et al 1 214 237 propose that kimberlite pipes can be grouped into three types or classes classical or class 1 pipes are the only class with characteristic low temperature diatreme facies kimberlite in addition to hypabyssal and crater facies kimberlite class 2 and 3 pipes are characterized only by hypabyssal and crater facies kimberlite in an increasing number of class 1 pipes a new kimberlite facies transitional facies kimberlite is being found in most cases this facies forms a zone several metres wide at the interface between the hypabyssal and diatreme facies the transitional facies exhibits textural and mineralogical features which are continuously gradational between the hypabyssal and the diatreme types the textural gradations are from a coherent magmatic texture to one where the rock becomes increasingly magmaclastic and this is accompanied by concomitant mineralogical gradations involving the decline and eventual elimination of primary calcite at the expense of microlitic diopside both transitional and diatreme facies kimberlites are considered to have formed in situ from intruding hypabyssal kimberlite magma as a consequence of exsolution of initially co 2 rich volatiles from the volatile rich kimberlite magma the transitional facies is initiated by volatile exsolution at depths of about 3 km below the original surface with subsequent cracking through to the surface and resultant rapid decompression the further catastrophic exsolution of volatiles and their expansion leads to the formation of the diatreme facies thus diatreme facies kimberlite and class 1 pipes are emplaced by essentially magmatic processes rather than by phreatomagmatism distinctly different petrographic features characterize crater facies kimberlite in each of the three pipe classes in crater facies kimberlites of class 1 pipes small pelletal magmaclasts and abundant microlitic diopside are characteristic these features appear to reflect the derivation of the crater facies material from the underlying diatreme zone most class 2 pipes have shallow craters and the crater facies rocks are predominantly pyroclastic kimberlites with diagnostic amoeboid lapilli which are sometimes welded and have vesicles as well as glass possible kimberlite lava also occurs at two class 2 pipes in n angola the possible presence of lava as well as the features of the pyroclastic kimberlite is indicative of hot kimberlite magma being able to rise to levels close to the surface to form class 2 pipes most class 3 kimberlites have very steep craters and crater facies rocks are predominantly resedimented volcaniclastic kimberlites in some cases characterized by the presence of abundant angular magmaclasts which are petrographically very similar to typical hypabyssal facies kimberlite found in class 1 pipes the differences in crater facies kimberlite of the three classes of pipe reflect different formation and depositional processes as well as differences in kimberlite composition specifically volatile composition kimberlite forming pipe classes 1 and 3 is thought to be relatively water rich and is emplaced by processes involving magmatic exsolution of volatiles the kimberlite magma forming class 2 pipes is co 2 rich can rise to shallow levels and can initiate phreatomagmatic emplacement processes

opaque assemblages in cr2 graves nunataks gra 06100 as indicators of shock driven hydrothermal alteration in the cr chondrite parent body we have studied the petrologic characteristics of sulfide metal lodes polymineralic fe ni nodules and opaque assemblages in the cr2 chondrite graves nunataks gra 06100 one of the most altered cr chondrites unlike low petrologic type cr chondrites alteration of metal appears to have played a central role in the formation of secondary minerals in gra 06100 differences in the mineralogy and chemical compositions of materials in gra 06100 suggest that it experienced higher temperatures than other cr2 chondrites mineralogic features indicative of high temperature include 1 exsolution of ni poor and ni rich metal from nebular kamacite 2 formation of sulfides oxides and phosphates 3 changes in the co ni ratios and 4 carbidization of fe ni metal the conspicuous absence of pentlandite may indicate that peak temperatures exceeded 600 c opaques appear to have been affected by the action of aqueous fluids that resulted in the formation of abundant oxides fe rich carbonates including endmember ankerite and the sulfide silicate phosphate scorzalite we suggest that these materials formed via impact driven metamorphism mineralogic features indicative of impact metamorphism include 1 the presence of sulfide metal lodes 2 the abundance of polymineralic opaque assemblages with mosaic like textures and 3 the presence of suessite initial shock metamorphism probably resulted in replacement of nebular fe ni metal in chondrules and in matrix by ni rich co rich fe metal al ti cr rich alloys and fe sulfides while subsequent hydrothermal alteration produced accessory oxides phosphates and fe carbonates an extensive network of sulfide metal veins permitted effective exchange of siderophile elements from pre existing metal nodules with adjacent chondrules and matrix resulting in unusually high fe contents in these objects

the geology of kimberlite pipes of the ekati property northwest territories canada abstract this paper reviews key characteristics of kimberlites on the ekati property nwt canada to date 150 kimberlites have been discovered on the property five of which are mined for diamonds the kimberlites intrude archean basement of the central slave craton numerous proterozoic diabase dykes intrude the area the precambrian rocks are overlain by quaternary glacial sediments no phanerozoic rocks are present however mudstone xenoliths and disaggregated sediment within the kimberlites indicate that late cretaceous and tertiary cover likely

salts in southern yakutian kimberlites and the problem of primary alkali kimberlite melts abstract alkali carbonates sodalite gypsum anhydrite halite and sylvite are present in the groundmass and matrix of many kimberlites in the southern part of the yakutian kimberlite province the kimberlites were emplaced through 2 km thick evaporite bearing carbonate sediments saturated with brines in the global context southern yakutian kimberlites are unprecedented in the amount of the crustal carbonate and evaporite material included in the pipes as evidenced by the bulk major element chemistry and isotopic compositions of sr c o cl and s we present geological and hydrogeological data on country rocks and kimberlites of the udachnaya mir and international naya pipes the secondary crustal origin of na k cl and s rich minerals is supported by the following 1 a regional correlation between the geology and hydrogeology of the local country rocks and the kimberlite mineralogy in particular the difference between southern and northern yakutian kimberlites 2 a restriction of halite or gypsum mineralization in the mir and international naya pipes to depths where pipes intersect country rock strata with similar mineralogy 3 the localization of the highest abundances of na k cl s bearing minerals in the udachnaya east kimberlite at a depth interval that correlates across three magmatic phases of kimberlites and coincides with the roof of the halite bearing country rock and an aquifer carrying anomalously na rich brines 4 the presence of evaporite xenoliths and veins of halite gypsum and carbonate cutting through the kimberlite and xenoliths 5 a secondary origin of halite and alkali carbonates as observed in their textural relationships to serpentine and other groundmass minerals 6 the geochemical and isotopic evidence for crustal contamination addition of crustal salts to kimberlite melt began prior to the volcanic fragmentation as a result of preferential melting and assimilation of evaporite xenoliths and may have continued in situ after the pipe emplacement via reactions with external saline fluids the hybrid alkali s and cl rich compositions of residual melts and fluids were trapped in secondary inclusions in olivine the crustal origin of salts in the udachnaya east kimberlite demonstrated here is incompatible with a model of alkali rich primary kimberlite melt it is significantly more ca na b and s rich than the deep seated mantle k and ba rich fluid inclusions in fibrous diamonds our analysis suggests that the udachnaya east kimberlite is not exceptional and uniquely fresh but rather typical of the other crust contaminated southern yakutian kimberlites

a synoptic and statistical description of the gulf stream and subtropical gyre using sofar floats abstract trajectories of 17 sofar floats ballasted to nominal depth of 700 and 2000 m and tracked for 15 months have been analyzed to produce synoptic and statistical descriptions of the gulf stream and subtropical gyre sofar floats launched in and near the gulf stream along with positions of the surface gulf stream and satellite tracked buoys demonstrate strong baroclinic shear nevertheless the horizontal patterns of the gulf stream meanders and gulf stream rings are the same at the surface and at 700 and 2000 m depth above the thermocline particle speeds greater than the propagation speed of the meanders cause parcels of water to move with the flow pattern at greater depths the velocities are at most equal to the propagation speed and the deep trajectories are free to pass through the gulf stream or ring strong temporal variability is found near the tail of the grand banks instances of flow both southward into a narrow gulf stream recirculation and northward into the north atlantic current can

metamorphic vanadian chromian silicate mineralization in carbon rich amphibole schists from the male karpaty mountains western carpathians slovakia mineralization involving vanadian chromian silicates has been studied in lower paleozoic carbon rich amphibole schists with pyrite and pyrrhotite near pezinok southwest slovakia a detailed electron microprobe study has revealed the presence of v cr rich garnet clinozoisite and muscovite associated with amphiboles magnesiohornblende tremolite actinolite and edenite diopside and albite the garnet contains 5 19 wt v 2 o 3 5 11 wt cr 2 o 3 and 2 13 wt al 2 o 3 16 64 mol goldmanite 19 36 mol uvarovite and 9 59 mol grossular end members the garnet is unzoned or shows v rich cores and al rich rims or irregular coarse oscillatory zoning with v cr and al locally involving ca and mn as well the v cr rich clinozoisite to mukhinite and chromian clinozoisite contains 2 9 5 wt v 2 o 3 and 1 5 11 wt cr 2 o 3 the muscovite contains 2 5 8 wt v 2 o 3 and 0 7 wt cr 2 o 3 the mineralization originated from primarily v cr and c rich mafic pyroclastic rocks affected by volcano exhalative processes these rocks were weakly metamorphosed during early hercynian regional metamorphism ml followed by late hercynian contact metamorphism m2 with crystallization of v cr rich silicates diopside amphiboles phlogopite titanite albite quartz carbonate pyrite and pyrrhotite the youngest alpine retrograde metamorphic event m3 is connected with production of v cr poor muscovite clinochlore clinozoisite pumpellyite mg prehnite quartz and carbonates under prehnite pumpellite facies conditions

how unique is the udachnaya east kimberlite comparison with kimberlites from the slave craton canada and sw greenland the origin of alkali carbonates and chlorides in the groundmass of unaltered udachnaya east kimberlites in siberia is still controversial contrary to existing dogma that the udachnaya east kimberlite was either contaminated by the crustal sediments or platform brines magmatic origin of the groundmass assemblage has been proposed on the basis of melt immiscibility textures melt inclusion studies and strontium and neon isotope compositions we further tested the idea of alkali and chlorine enrichment of the kimberlite parental melt by studying olivine hosted melt inclusions and secondary serpentine in kimberlites from the slave craton canada gahcho kue jericho aaron and leslie pipes and southern west greenland majuagaa dyke host olivine phenocrysts closely resemble groundmass olivine from the udachnaya east kimberlite in morphology compositions high fo low ca complex zoning with cores of varying shapes and compositions and rims of constant fo melt inclusions in olivine consist of several translucent and opaque daughter phases and vapour bubble s the daughter crystals studied in unexposed inclusions by laser raman spectroscopy and in carefully exposed inclusions by wds eds are represented by na k chlorides calcite dolomite magnesite ca na ca na k and ca mg ba carbonates bradleyite na3mg co3 po4 k bearing nahpoite na2 hpo4 apatite phlogopite and tetraferriphlogopite unidentified sulphates fe sulphides djerfisherite pyrochlore na ca 2nb2o6 oh f monticellite cr spinel and fe ti oxides high abundances of na k e g na k ca 0 15 0 85 and incompatible trace elements in the melt inclusions are confirmed by la icpms analysis of individual inclusions heating experiments show that melting of daughter minerals starts and completes at low temperatures 100oc and 600oc respectively further reinforcing the similarity with the udachnaya east kimberlite serpentine minerals replacing olivine in some of the studied kimberlites demonstrate elevated abundances of chlorine up to 3 4 wt especially in the early generation despite heterogeneous distribution of chlorine such abundances are significantly higher than in the serpentine in abyssal and ophiolitic peridotites 0 5 wt the groundmass of most kimberlites including those studied here and altered kimberlites from the udachnaya pipe contain no alkali carbonates and chlorides and have low na2o 0 2 wt we believe that alteration disturbs original melt compositions with the alkaline elements and chlorine being mostly affected however the compositions of melt inclusions and serpentine are indicative of the chemical signature of a parental kimberlite melt it appears that enrichment in alkalies and chlorine as seen in unaltered udachnaya east kimberlites is shared by other kimberlites and thus can be assigned to deep mantle origin