deep sea spoon worms echiura from the sea of okhotsk and the adjacent slope of the kuril kamchatka trench abstract during the sokhobio sea of okhotsk biodiversity studies expedition from july to august 2015 eleven sites across the kuril basin of the sea of okhotsk and the landward abyssal slope of the kuril kamchatka trench kkt off the bussol strait were surveyed and benthic communities were investigated samples comprised 260 echiurans from seven species of seven genera belonging to the family bonelliidae were collected at eight of the eleven sites of the sokhobio expedition the family bonelliidae is most common in abyssal and hadal environments in the world ocean with high abundances in all investigated regions the description of deep water echiurans from the sea of okhotsk is the first one based on complete collected specimens with living colouration the descriptions provide new information on the morphology and taxonomic details of the species which were previously noted from the northwestern pacific and described from damaged or incomplete specimens two species are identified as representatives of the two genera bengalus and bonelliopsis which never have been noted before in the northwestern pacific and the genus bengalus is reported for the first time in the pacific the knowledge of the geographic ranges of these genera are expanded and discussed

genesis of autochthonous and allochthonous apulian karst bauxites southern italy climate constraints abstract the apulian carbonate platform acp in southern italy has experienced several episodes of subaerial exposure which were in some cases associated with the formation of karst bauxite deposits the acp contains both autochthonous canyon like bauxite and allochthonous salento type bauxite with the latter having been derived from a weathered and eroded pristine bauxite deposit the remnants of this pristine bauxite are preserved as transported pebbles embedded in a clayey matrix the autochthonous bauxite and the pebbles of the allochthonous bauxite have the same texture of sub spheroidal components ooids dispersed in a fine grained matrix the fractal dimension of ooids from both deposits is very similar and corresponds to the growth of aggregates under a diffusion controlled process the ooids of the autochthonous bauxite have a different composition to those in the pebbles of the allochthonous bauxite because they formed under different climatic conditions during the turonian autochthonous bauxite ooids formed in alternating wet tropical conditions promoting al hematite formation and drier conditions favouring boehmite stability in the allochthonous pebbles ooids formed mainly in a dry climate promoting the formation of large boehmite cores the ooids matrix ratio and the geometrical features of the ooids reflect these climate differences the differences in composition and age post turonian of the salento type bauxite bedrock suggest that the pristine bauxite that produced the salento type pebbles was different in composition to and younger in age than the canyon like bauxite the latter probably formed during a middle campanian emersion event evidenced by large karstic cavities which is correlated with the subaerial exposure of karst recorded on the adriatic island of brac

giant bauxite deposits of south china multistage formation linked to late paleozoic ice age lpia eustatic fluctuations abstract the lower carboniferous jiujialu formation bauxite deposits at zunyi northern guizhou are distinguished by their great thickness to 110 m and cyclic alternation of bauxite ore and bauxitic claystone layers these features are typical of the kazakhstan subtype of karst bauxite deposits although the genesis of this type of deposit is poorly understood here we undertook a petrological mineralogical and geochemical study of the zunyi deposit in drillcore zk5600 to gain insights into its formation history the zunyi profile contains seven bauxite cycles as recorded by petrological mineralogical and geochemical features indicating a multistage formation history each cycle is composed of a lower bauxitic claystone layer and an upper bauxite ore layer the bauxite ore is characterized by high al2o3 high al mineral diaspore and low sio2 content positive ce anomalies high cia values 90 and strong depletion of major elements indicate that the bauxite ore formed through intense chemical weathering and leaching in a well drained soil environment the bauxitic claystone is characterized by relatively lower al2o3 and higher sio2 and clay mineral mostly illite content this lithology exhibits both negative and positive ce anomalies moderate cia values 70 80 and enrichment of some elements e g fe k indicating formation through moderate chemical weathering in a poorly drained soil environment secular variations in chemical weathering intensity and soil drainage conditions were linked to regional hydrologic changes during the early carboniferous the zunyi area was located in a karstified coastal upland setting and its hydrologic system was affected by glacio eustatic fluctuations high groundwater table elevations during eustatic highstands led to formation of bauxitic claystone layers whereas low groundwater table elevations during eustatic lowstands led to formation of bauxite ore layers

prediction of modern bauxite occurrence implications for climate reconstruction abstract the formation of bauxite and laterite strongly depends on prevailing climate we use modern climate and bauxite distribution data to investigate quantitatively the role of climate in bauxite formation and to develop a method for testing general circulation models gcms we find that a very satisfactory prediction for potential bauxite formation can be achieved using two different sets of criteria the first requires the mean annual temperature to be greater than 22 c with annual mean precipitation greater than 1200 mm and 6 or fewer months when the rainfall is less than 60 mm the alternative model requires precipitation greater than evaporation for at least 6 months per year and monthly mean temperatures greater than 23 c for at least 8 months these proxy models are also used with simulations of the present day using a general circulation model the results show that the climate models are robust suggesting that bauxitization can be used to evaluate quantitatively such climate models for ancient times we also show that based on climate model predictions the regions favourable for bauxitization have remained stable through the holocene but with the exception of the malay peninsula bauxite formation would have ceased at the last glacial maximum

mineralogical characteristics of the karstic bauxite deposits in the xiuwen ore belt central guizhou province southwest china abstract the karstic bauxite deposits in the xiuwen ore belt of central guizhou province are hosted by the lower carboniferous jiujialu formation and show parallel unconformity with the overlying and underlying strata the ore bearing rock series that exhibits a typical coal bauxite iron structure is divided into three segments from the bottom upward namely an iron layer a bauxite layer and a coal layer based on the textural features and iron abundances the bauxite ores occurring in the middle segments are divided into three types of ores clastic compact and high iron the bauxite ores primarily comprise diaspore boehmite kaolinite illite and hematite with minor zircon pyrite rutile and feldspar the existence of rutile within diaspore lumps which were inherited from laterization suggests that diaspore was transformed from gibbsite and that karstic bauxite was transformed from laterite bauxite the results of x ray diffraction xrd scanning electron microscopy sem and electron probe x ray microanalyses epma suggest that diaspore and boehmite differ with regard to appearance and element abundance diaspore 2 10 m displays short prismatic or platy shapes and contains low sio2 abundances ranges from 0 2 to 0 51 wt whereas boehmite 0 2 5 m exhibits granular or irregular shapes and contains high contents of sio2 that vary between 2 71 and 10 4 wt the fe cu pb zn ba sulfide and sulfate mineral assemblages associated with cryptocrystalline kaolinites are discovered in the xiaoshanba deposit from the xiuwen ore belt mineralogical and geochemical studies reveal that the genesis of these assemblages is controlled by the decomposition processes of organic matter and the activities of microorganisms within the ore bearing rock series geochemical data suggest that elements rich in high organic cryptocrystalline kaolinite are produced from the adsorption effect of organic matter whereas the low concentration of these elements in pure kaolinite can be attributed to the scavenging effect during kaolinite crystallization in addition coexisting organic matter cryptocrystalline kaolinite and sulfide and sulfate minerals see sample xsb 14 indicate that the forming environment of the bauxite was hot humid tropical or subtropical climates

microfacies and carbon isotope records of mississippian carbonates from the isolated bama platform of youjiang basin south china possible responses to climate driven upwelling changes in mississippian global paleogeography derived from the reconfiguration of the continents have been suggested to result in a change in oceanic circulation carbon cycling as well as in global cooling here integrated 13ccarb chemostratigraphy and foraminiferal biostratigraphy across the mississippian late tournaisian visean early serpukhovian mfz6 mfz16 foraminiferal biozones of the gongchuan section located in the isolated bama platform in the youjiang basin south china are presented the 13ccarb trend shows an abrupt decline during late visean asbian early brigantian mfz13 14 this decline is also observed in subequatorial western euramerica whereas coeval sections in subequatorial eastern euramerica show consistently elevated 13c values across the entire visean the 13c decline in western euramerica and the south china block eastern paleo tethys coincides with a global regression with a suggested glacioeustatic origin the onset of high frequency climate and sea level oscillations and the closure of the rheic seaway between euramerica and gondwana we propose a model explaining the divergence of 13c records resulting from the closure of the rheic seaway and development of upwelling zones in the western margin of euramerica and the eastern paleo tethys realm quantitative microfacies analysis across the mississippian succession in the gongchuan section shows facies independent disappearance of corals and increased proportion of cortoids and filter feeding organisms at the onset of the asbian 13c decline which may support an increase in nutrient level that can be expected as a result of upwelling

intensified oceanic circulation during early carboniferous cooling events evidence from carbon and nitrogen isotopes abstract the early carboniferous was a climatic transition interval from a mid paleozoic greenhouse world into the late paleozoic ice age it was marked by a long term cooling trend that was punctuated by short glaciations in the tournaisian and visean early to mid early carboniferous here we generated organic carbon and nitrogen isotope profiles for two widely separated lower carboniferous sections arrow canyon range nevada and namur dinant basin belgium in order to assess the global nature and timing of changes in the carbon nitrogen cycles linked to oceanic productivity and redox conditions during this climatic transition interval the carbon and nitrogen isotope profiles of both study sections record major perturbations during the mid tournaisian and visean a mid tournaisian event tice is marked by increases in 13ccarb 13corg and 15nbulk at arrow canyon from 0 6 to 7 0 25 2 to 23 7 and 0 6 to 8 9 respectively and namur dinant from 0 3 to 4 7 27 9 to 22 2 and 5 7 to 5 2 respectively an early visean event vice named herein is marked by increases in 13ccarb 13corg and 15nbulk at arrow canyon from 0 6 to 3 1 28 4 to 23 6 and 1 4 to 9 4 respectively and namur dinant from 2 1 to 4 3 26 7 to 25 0 and 1 4 to 3 3 respectively the positive excursions in all three isotopic records during these events are consistent with increased fractional burial of organic carbon and enhanced denitrification implying intensification of marine productivity and expansion of hypoxia in the global ocean given that each event coincided with lowering of sea surface temperatures and increased glaciation as documented from published conodont 18o and sea level records we hypothesize that global cooling led to intensified oceanic circulation and upwelling on continental margins triggering increased marine productivity and attendant redox changes within the affected upwelling zones our results provide new insights into changes in early carboniferous oceanic conditions in response to the initial stages of cooling leading into the late paleozoic ice age

ree and other trace elements in a granitic weathering profile from serre southern italy abstract ree v cr ni rb sr y zr and nb behaviour in a granitic weathering profile in southern italy is studied in the saprolites of the considered profile depletion of v cr ni rb sr zr and nb is observed this is quite remarkable for sr and cr whereas ree and y are enriched in the more altered portion of the profile and especially in its m fraction such enrichment is associated with the lree hree fractionation and the positive ce anomaly the former results from an increased solubility of hree in a non acid environment as well as from the removal of the hree rich phases from the residual component the latter is related to the redox chemistry of ce which as ceo 2 is less soluble than the other ree no analogy is observed between the behaviour of ce and fe mn and cr saprolites also exhibit a negative eu anomaly which is mostly inherited from the parental material finally the influence of accessory minerals in the ree distribution of weathering products and in sediments calls for a careful evaluation of preferential settling phenomena of heavy minerals during transportation and deposition processes this is especially true in the parent material sediment relationships

climatic and hydrologic controls on upper paleozoic bauxite deposits in south china abstract the late paleozoic era was an interval of major tectonic and climatic changes including formation of the supercontinent pangea and the 60 myr long late paleozoic ice age lpia although bauxite formation declined globally from the carboniferous to the permian in conjunction with global cooling it was an interval of widespread bauxite formation in china in south china 1 the jiujialu formation bauxite deposits in central and northern guizhou zunyi area are of early middle visean age 2 the dazhuyaun formation bauxite deposits in northern guizhou wuchuan zheng an daozheng area to southern chongqing nanchuan area and southeastern guizhou fuquan kaili area are of late pennsylvanian early permian age and 3 the heshan formation bauxite deposits in western guangxi to yunnan are of middle late permian age in north china the benxi formation bauxite deposits are of late mississippian middle pennsylvanian age the contrasting trends in bauxite metallogenesis between china and the rest of the world imply different climatic patterns in the eastern tethys high annual humidity with seasonal dryness and pangea aridification this hypothesis is further supported by differences in the chemical index of alteration or cia 80 in the eastern tethys vs 50 in western pangea and in paleotemperatures mean annual temperature or mat 20 c in the eastern tethys vs 4 c in western pangea determined from permo carboniferous siliciclastic deposits permo carboniferous bauxite deposits in south china formed in coastal plain and coastal karstic depression environments in which the position of the groundwater table was related to sea level changes during the late paleozoic high frequency eustatic fluctuations caused by waxing and waning of gondwana icesheets controlled sedimentation in these coastal depositional systems leading to cyclic accumulation of coal and bauxite deposits and cycles of vadose and phreatic type bauxite formation the results of the present study show that during interglacial stages lateritization resulted from high pco2 high sea level and groundwater table elevations low precipitation and limited vegetation cover whereas during glacial stages bauxitization of these ferralitic weathering products was promoted by low pco2 low sea level and groundwater table elevations high precipitation and more extensive vegetation cover thus a unique combination of geographic climatic and eustatic factors accounted for widespread formation of bauxite in south china during the lpia

woce section p1w in the sea of okhotsk 1 oceanographic data description we describe the results of a world ocean circulation experiment woce survey line p1w from the open pacific ocean through the bussol strait and across the sea of okhotsk observations are presented of distributions of temperature and salinity dissolved oxygen and nutrients and some derived quantities discussion centers on the distribution of the sea of okhotsk component of the north pacific intermediate water mass and its properties the sea of okhotsk has been suggested as the only location where deep convection may occur within the north pacific or its marginal seas our analysis suggests that the surface 26 85 has recently been ventilated and arguments might be made to suggest that ventilation has occurred to 27 05 this is discussed here but detailed evidence is covered in a companion paper analyzing cfc observations the okhotsk component of the north pacific intermediate water extends to substantially greater depths and densities and so some other process is needed to create the denser water mass

mobilization and redistribution of rees and thorium in a syenitic lateritic profile a mass balance study abstract ree th geochemistry and mineralogy have been studied in a lateritic profile derived from a syenite at akongo in sw cameroon ree and th mass balance calculations for the host rock minerals show that at least 70 of the lree s and 50 of the hrees are contained in allanite apatite titanite and epidote and at least 50 of the th is controlled by the same accessory minerals which represent about 2 wt of the unaltered syenite these accessory phases are destroyed during the first stages of weathering causing most of the rees and th to be rapidly released into the soil comparison of the variation in the zr ti and th content as a function of the apparent density of the different zones of the saprolite shows that th is the least mobile element the presence of secondary thorianite tho2 the etched surface on zircon grains and the presence of ti in secondary cerianite support this geochemical interpretation the concentration of thorium was therefore chosen as invariant relative to the concentration of the other elements especially the rees in mass balance calculations most of the rees are leached in the iron rich upper horizons loose nodular horizon iron crust and top of mottled clay horizon where the groundwater table moves saprolite and bottom of the mottled clay horizon the rees are fractionated and redistributed there is a juxtaposition of leached and accumulation zones with precipitation of lree aluminous hydrated phosphates this study supports the existence of two different cycles for the redistribution of elements in the soil 1 1 as dissolved ions in the saprolite horizon and 2 2 as individual particles in the upper part of the profile

global events of the late paleozoic early devonian to middle permian a review abstract the late paleozoic early devonian to middle permian was an interval of profound changes in earth surface systems reflected in dynamic interplay among the biosphere hydrosphere atmosphere and geosphere major events transpired including the colonization of landmasses by vascular plants the assembly of the supercontinent pangea two first order mass extinctions the frasnian famennian and devonian carboniferous boundary events and the most severe icehouse climate mode of the phanerozoic the late paleozoic ice age lpia the goals of the present review are 1 to summarize major global developments in climate oceanography and paleobiology during the late paleozoic 2 to examine the roles of land plant evolution global tectonics and large igneous province magmatism in driving these developments and 3 to serve as an introduction to the 23 contributions to this special issue of palaeogeography palaeoclimatology palaeoecology indicating how they advance our knowledge of various scientific issues related to these developments

discovery of the ree minerals and its geological significance in the quyang bauxite deposit west guangxi china most of the karstic bauxite deposits in china are enriched in ree and the ree has commonly been considered to be adsorbed on the surface of clay or diaspore minerals as ion state however occurrence of ree minerals in the bauxite deposits has not been reported by far in the quyang bauxite deposit from guangxi province we find ree minerals the minerals are parisite and churchite parisite is widely distributed in the ooids and matrix inducing positive ce anomaly of the ores whereas churchite is rare and occurred in the core of ooid the compositions of the ree minerals show the eu anomaly can change gently during the weathering and the eu anomaly analyses suggest that the ree in the ores are mostly derived from the underlying carbonates the parisite is formed in an alkaline condition while churchite in an acidic situation the co existence of the two minerals in the ores suggests the permian environment for bauxite formation is complex with great change of ph value moreover parisite is inferred to be formed earlier than the churchite

importance of hydrogeological conditions during formation of the karstic bauxite deposits central guizhou province southwest china a case study at lindai deposit abstract karstic bauxite deposits are widespread in central guizhou province sw china and high grade ores are frequently sandwiched with overlying coal and underlying iron rich layers and form a special coal bauxite iron structure the lindai deposit which is one of the most representative karstic bauxite deposits in central guizhou province was selected as a case study based on textural features and iron abundances bauxite ores in the lindai deposit are divided into three types of ores i e clastic compact and high iron the bauxite ores primarily comprise diaspore boehmite kaolinite illite and hematite with minor quartz smectite pyrite zircon rutile anatase and feldspar the al 2 o 3 53 76 8 wt is the main chemical contents of the bauxite ore samples in the lindai district followed by sio 2 fe 2 o 3 tio 2 cao mgo s and p etc our geological data on the lindai deposit indicated that the ore bearing rock series and its underlying stratum have similar rare earth elements distribution pattern and similar y ho zr hf and eu eu values additionally all ore bearing rock samples are rich in mgo range from 0 16 wt to 0 68 wt and the plots of the dolomites and laterites lie almost on or close to the weathering line fit by the al bearing rocks in zr vs hf and nb vs ta diagrams suggesting that the underlying middle cambrian shilengshui formation dolomite is the parent rock of bauxite resources in the lindai district simulated weathering experiments on the modern laterite from the shilengshui formation dolomite in the lindai bauxite deposit show that hydrogeological conditions are important for karstic bauxite formation si is most likely to migrate its migration rate is several magnitudes higher than those of al and fe under natural conditions the reducing inorganic acid condition is the most conducive to al enrichment and si removal fe does not migrate easily in groundwater al enrichment and fe removal can occur only in acidic and reducing conditions with the presence of organic matter the geological and experimental studies show that coal bauxite iron structure in lindai deposit is formed under certain hydrogeological conditions i e since lateritic bauxite or al rich laterite deposited upon the semi closed karst depressions si can be continuously removed out under neutral acidic groundwater conditions the coal carbonaceous rock overlying the bauxitic materials were easily oxidized to produce acidic h 2 s h 2 so 4 etc and reductant groundwater with organic materials that percolated downward resulting in enrichment of al in underlying bauxite it also reduced fe 3 to its easily migrating form fe 2 moving downward to near the basal carbonate culminated in precipitating of ferruginous fes 2 feco 3 etc strata of the coal bauxite iron structure thus the bauxitic materials experienced al enrichment and si and fe removal under above certain hydrogeological conditions forming the high quality bauxite

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

cerium anomalies in lateritic profiles the ree geochemistry and mineralogy have been studied in four lateritic profiles one derived from a syenite akongo sw cameroon the others being developed on a gneissic basement and located along a soil toposequence goyoum e cameroon there is a fractionation between lree and hree in the lateritic samples during weathering the weathered residual products being enriched in lree from la to eu and depleted in hree from gd to lu sampled waters are enriched in hree in relation to the syenite host rock a positive ce anomaly has been found systematically at the top of the saprolite beneath a zone of iron oxide accumulation in the laterite up to 2000 ppm ce may be present in the akongo profile cerianite ceo2 is present as very fine coatings in non ferruginous clayey domains primary ree bearing accessory minerals are weathered at the bottom of the profile specifically allanite and apatite are transformed into florencite and rhabdophane but these phases have no ce anomaly all the data are interpreted as the result of the following processes 1 1 ree leaching in a reducing environment 2 2 oxidation of ce3 to ce4 in an oxidizing environment 3 3 deposition of cerium as cerianite whereas the other ree remain in solution

the chemical character of fluids forming diagenetic illite in the southern appalachian basin diagenetic illite mixed layer illite smectite i s from ordovician and devonian potassium bentonite k bentonite and shales was studied in the proximal southern appalachian basin alabama through virginia to understand in more detail the timing of illite formation as well as attempt to describe the chemistry of the fluids that formed illite during the alleghanian orogeny through combined k rb and oxygen isotope analyses the clay fraction of the k bentonites is composed predominantly of illite smectite i s and chlorite most i s exhibited kalkberg order iisi with 85 illite layers the k ar dates of i s from ordovician k bentonites and devonian k bentonites mostly range from 260 310 ma and indicate i s formed during the alleghanian orogeny internally concordant dates and similar percentages of illite layers of i s are measured from several samples collected within a thick 1 m ordovician k bentonite at fort payne alabama the oxygen isotopic values 1 8 o of i s range from 18 23 smow at lowest levels of thermal maturity and burial as seen by conodont alteration index values cai of 1 5 2 0 the range in 1 8 o values of water in equilibrium with i s is 2 5 3 5 at higher thermal maturity cai 2 5 4 5 the 1 8 o of water in equilibrium with i s is from 4 5 to 12 the 1 8 o analyses are mostly consistent with i s having formed in the presence of orogenic i e saline waters the mean k rb of the appalachian illites from this study is 325 n 20 this mean k rb is also consistent with the formation of diagenetic i s in the presence of a saline fluids having higher k activities than meteoric waters the combined data indicate these diagenetic illites in k bentonites formed from saline orogenic waters during the alleghanian orogeny along the valley and ridge province in the southern appalachian basin although the data rule out formation of diagenetic illite in the presence of meteoric water or long term reaction with connate formation waters the combined data cannot distinguish the source and the mechanism tectonic push or flush from tectonic highlands for the movement of saline fluids in the appalachian basin

wavelet analysis of well logging data from oil source rock egret member offshore eastern canada wavelet analysis is a sensitive method for automatically detecting and distinguishing abrupt discontinuities i e faults unconformities cyclicity and gradual changes in sedimentation rate by transforming depth related sedimentary signals i e gamma rays into wavelengths at distinct depth intervals we used wavelet analysis for evaluation of the spatio temporal distribution of oil source rocks and for estimating accumulation rates in a sedimentary basin having high resolution the method was applied to 16 gamma ray logs from the jurassic egret member an oil source rock succession 55 m to 227 m in thickness offshore eastern canada dominant gamma ray cycles having wavelengths varying from 2 8 m western margin of the basin to 24 m eastern part of the basin have been detected by wavelet analysis the coincidence of the ratio of predominant gamma ray cycles with the ratio of milankovitch spectra about 400 100 40 20 k y suggests that climatic cycles are an important factor controlling sedimentary cyclicity in the egret member dominant wavelengths likely represent 100 k y eccentricity giving accumulation times of 1 9 m y for stratigraphically complete sections having 19 successive 2 8 m gamma ray cycles and giving accumulation times of 600 k y for incomplete successions having only 6 cycles up to four discontinuities occur in gamma ray log cyclicity and separate the egret member into subunits we interpret the discontinuities as unconformities or faults and as related to sediments having low petroleum potential the stratigraphic completeness of the egret member is correlated to total mass of organic carbon and decreasing thickness of non source rock intervals having correlation coefficients of r 0 8 and r 0 76 respectively

potassium sources and illitization in texas gulf coast shale diagenesis abstract the aim of this paper is to identify the controls on the rates of illitization in texas gulf coast shales under diagenetic conditions two different mineral transformations are considered the transformation of smectite to nearly illite and the precipitation of discrete illite i e the formation of pure illite analyses of potassium feldspar and kaolinite abundance in addition to k2o al2o3 and tio2 contents in shales from three wells are used to supplement published data in order to identify the mineral reactions responsible for the smectite to illite transformation in shales involving illite smectite i s mineral series these data indicate that the first stage of the smectite to illite reaction in shales r 0 structures ca 0 50 illite content is controlled by the presence of feldspar and hence also by the dissolution kinetics of feldspar the empirically derived activation energy for the first i s transformation in shales is similar to that for k feldspar dissolution kaolinite is not involved in this transformation in the shales investigated the second stage of the reaction sequence r 1 structures ca 50 100 illite content occurs after potassium feldspar has largely or completely disappeared from the shale system this indicates that the feldspar no longer controls the second stage of the smectite to illite transformation and suggests another external source of potassium for the reaction in the shales this assumption is supported by the relative increase of potassium content of the shales at least in two of the three studied wells kaolinite does not seem to be involved either in this second stage of the i s reaction sequence the formation of discrete illite crystallites in shales is independent of the i s transformation reactions and takes place only after a very significant period of time has elapsed the slow rate of this reaction reflects the low activity of potassium in solutions that are in equilibrium with shale in comparison with sandstones where a rapid precipitation of pure illite can in some cases be observed it is suggested that the different reactions in the smectite to illite transformation necessitate different sources of potassium either from within or outside an argillaceous whole rock system these different sources of potassium give rise to different rates for the i s conversion reaction and the formation of illite

deep water bryozoa from the kuril basin sea of okhotsk abstract benthic samples collected at six stations in the kuril basin sea of okhotsk at depths of 3301 to 3366 m and at two northwestern pacific stations in bussol strait and on the western slope of the kuril kamchatka trench at depths 2267 and 3374 m yielded three cyclostome two ctenostome and two cheilostome bryozoan species among these oncousoecia viskovae sp nov is the deepest record for a species in this genus triticella maiorovae sp nov a symbiont on a sipunculid worm is the second species of the genus discovered in the northwestern pacific our study yielded the deepest records for bicrisia abyssicola and buchneria teres and the first records for triticella minini and b teres from the sea of okhotsk the proportion of cheilostomes in the samples was much lower than expected from previous studies although the sample size and total diversity were also low dead colonies of four cheilostome species einhornia arctica porella alba cryptosula zavjalovensis and cheilopora praelucida were found encrusting pebbles at two abyssal sites we interpret these as allochthonic elements due to ice transport of pebbles from shallow waters to the kuril basin stenobathic and eurybathic species common to both the kuril basin and northwestern pacific indicate connectivity between deep water faunas in these adjacent regions

mass change calculations in altered rock series a technique is presented whereby precursors of altered rocks in a fractionated rock series can be identified and changes in chemical components mass and volume accurately calculated the procedure utilizes elements with high degrees of immobility in hydrothermal and associated interactive water rock systems igneous rock series and sedimentary and metamorphic rocks with primary continuity of chemical composition are amenable to this treatment in the procedure for igneous rocks best fit fractionation lines are established for an immobile igneous compatible incompatible element pair the latter element functioning as the fractionation monitor alteration paths are linear and pass through the origin intersections of the fractionation and alteration lines yield the immobile element concentrations in the precursors to the altered rocks mobile components are determined from fractionation lines and monitor values total mass changes are proportional to the displacement of altered samples from the fractionation line masses of other elements in an altered sample reconstructed values are recalculated to the concentration of the monitor element in the precursor chemical changes are the differences between the calculated precursor compositions and the reconstructed altered rock compositions errors are mainly a function of the positioning of the fractionation lines

the ciw index a new chemical index of weathering abstract a new chemical index of weathering that can be applied to modern soils and precambrian paleosis is proposed ciw al2o3 the value of this index increases as the degree of weathering increases and the difference between ciw index values of the silicate parent rock and soil or sediment reflects the amount of weathering experienced by the weathered material

geochemistry of the apulian karst bauxites southern italy chemical fractionation and parental affinities article i nfo this study focuses on a late cretaceous karst bauxite deposit in the murge area of the apulia district southern italy the first analysis of the vertical distributions of a wide range of elements including rees and selected trace elements throughout the deposit was shown in order to identify the processes determining element frac tionation during the evolution of the bauxite the studied karst bauxite deposit exhibits an ooidal texture is mineralogically homogeneous and contains higher abundances of boehmite than of hematite kaolinite and anatase the major element composition of the bauxite is dominated by elevated concentrations of sio2 t io2 a l2o3 a nd fe2o3 and analyses of element mo bility within the bauxite indicate that all elements except for nb and ni and to a lesser extent cr are depleted relative to the immobile element ti r mode factor analysis revealed a number of key findings i some low solubility elements e g zr th ti v ga were concentrated in detrital zircon and monazite zr th in anatase ti v and possibly in boehmite and hematite ga during the later stages of bauxitisation ii fe and cr were concentrated during wet conditions whereas al and co accumulated during dry conditions iii distributions of the light rees lrees and the heavy rees hrees are controlled by the same processes suggesting that little lree hree fractionation occurred during bauxite formation and iv the behaviour of cerium is different from that of the other rees and highly variable cerium anomalies are observed across the deposit with three characteristic ce ce maxima with values ofn2 parisite was the only authigenic cerium mineral detected during this study thus we propose a three step model to explain the distribution of ce cerianite is dissolved by cerium reduction is transported by downward moving meteoric water per descensum and finally parisite is precipi tated this cycle was repeated several times in the apulian karst bauxite in response to eh decreases under alka line conditions promoted by fluctuations in the groundwater level finally we used the value of the eu anomaly todiscuss theparental affinity or protolith of thebauxite the value of the eu anomaly min eu eu 0 76 max eu eu 0 89 indicates that the bauxite was not derived from carbonates but rather that the majority of the bauxite was influenced by intermediate to mafic magmatic sources eu eu vs sm nd diagram suggests that the parental material for the bauxite was derived from a combination of a distant magmatic source and clastic material derived from a continental margin northern africa to the south

deep sea echinoderms of the sea of okhotsk abstract new samples of abyssal echinoderms taken in the sea of okhotsk by the sokhobio expedition have been examined and analyzed taking into account this new data 34 echinoderm species are distributed deeper than 2000 m in the sea of okhotsk among them 10 species are found in the sea of okhotsk for the first time and 6 species are found in the abyssal zone of the sea of okhotsk for the first time the species richness of the abyssal echinoderm fauna in the north west pacific areas north of 30 n and west of 180 e negatively correlates with the level of their geomorphological isolation the higher the level of isolation of the area the lower the species richness of its abyssal fauna the number of echinoderm species in the abyssal zone is found to be 9 in the most isolated sea of japan 34 species in the semi enclosed sea of okhotsk and 47 species in the least isolated bering sea more than 58 species occur in the open north west pacific abyssal area the new data on echinoderms indicates both submergence of the sublittoral bathyal species and dispersal of the abyssal species through the deep straits into the kuril basin of the sea of okhotsk among the abyssal echinoderms of the sea of okhotsk pseudoabyssal and true abyssal species account for 24 and 35 respectively the influence of the antarctic and west pacific deep sea centers of fauna redistribution is discussed

ce anomalies in the textural components of upper cretaceous karst bauxites from the apulian carbonate platform southern italy the chemical and mineralogical composition of upper cretaceous apulian karst bauxites southern italy and their textural components i e ooids and matrix has been studied the bulk samples are composed of boehmite hematite anatase and kaolinite the samples collected along a vertical profile show a downward enrichment for the elements rb sr ba ni and cr a similar distribution is observed in deposits bauxitized in situ at the expense of matrix like material collected in the karst zone the ooids consist mainly of hematite with minor boehmite and anatase whereas in the matrix boehmite prevails on hematite kaolinite and anatase in the void fillings in the matrix there is a ca fluorocarbonate having a ce ce of 5 8 the ooids with the exception of ce are enriched in ree and show a higher la yb ch ratio relative to the matrix the matrix exhibits a large positive ce anomaly whereas the ooids have negative ce anomaly the ce fractionation between the textural components can be explained assuming 1 ce oxidation and cerianite precipitation in the uppermost part of the deposits 2 scavenging of ree from ce depleted percolating solutions by the iron oxide inducing both ree enrichment and ce negative anomalies in ooids 3 remobilization of cerium as fluoride complex as a consequence of more acidic conditions in the uppermost part of the deposit and precipitation of ce3 as fluorocarbonate mineral toward the carbonate bedrock barrier at alkaline ph alternatively the cerium remobilization possibly as a carbonate fluoride complex could be due to an eh decrease favoured by a rise of the groundwater level

bivalve mollusks of the kuril kamchatka trench northwest pacific ocean species composition distribution and taxonomic remarks abstract the kuril kamchatka trench with a maximum depth of 9600 m is one of the deepest trenches of the world ocean and has the second after the izu bonin trench largest area of hadal habitat investigation of the materials collected by the kurambio ii german russian expedition rv sonne 2016 8 stations and two russian expeditions rv vityaz 1953 1966 18 stations from the hadal zone of the kuril kamchatka trench 6000 9583 m depth revealed a rich fauna of bivalves including 33 species identified species and morphospecies belonging to 15 families of which 18 species 54 0 were determined to the species level and 14 species 42 4 were first recorded for the kuril kamchatka trench of the 33 species found in the kuril kamchatka trench 15 species 45 5 were recorded outside the trench at depths of less than 6000 m vesicomya sergeevi filatova 1971 and parayoldiella ultraabyssalis filatova 1971 formed the most abundant populations in the trench 72 9 of all specimens of bivalves collected by the kurambio ii expedition and were predominant in samples from the trench bottom in the hadal zone of the kuril kamchatka trench 3 depth ranges 6000 6999 7000 8999 9000 9583 m were distinguished that differ in the species composition of bivalves the bivalve fauna of the upper hadal zone of the kuril kamchatka trench depths 6000 6999 m is characterized by the highest species richness 23 species and is represented mainly 65 2 by bathyal hadal and abyssal hadal species this depth range is considered as a zone of transition between the abyssal and hadal zones the fauna of this transitional zone is most closely connected with the fauna of the abyssal plain adjacent to the trench at depths of more than 7000 m the proportion of hadal endemics significantly increases more than 66 at the maximum depth of the trench over 9500 m only 5 species were recorded of the 18 identified species only 6 species 33 3 were found exclusively in the hadal zone of the trench photographs taxonomic remarks and distribution are provided for all identified species that were found in the hadal zone of the kuril kamchatka trench taxonomic decisions herein bathyspinula vityazi filatova 1964 is a distinct species and not a synonym of bathyspinula calcarella dall 1908 ledella spinuliformis f r bernard 1989 is synonymized with ledellina formabile filatova and schileyko 1984 following krylova 1993 myonera demistrata allen and morgan 1981 is considered as a synonym of bathyneaera hadalis knudsen 1970

first insights into macrofaunal composition from the sokhobio expedition sea of okhotsk bussol strait and northern slope of the kuril kamchatka trench abstract macrofauna 46 343 invertebrates from 41 taxa were collected by means of a camera epibenthic sledge c ebs during the expedition sokhobio sea of okhotsk biodiversity studies on board of the rv akademik m a lavrentyev in 2015 in total 11 sites and 22 stations were sampled at bathyal and abyssal depths ranging from 1696 m to 4798 m in the kuril basin of the sea of okhotsk 16 stations the bussol strait two stations and western slope of the kuril kamchatka trench kkt four stations polychaetes occurred most frequently in the samples with 17 546 individuals followed by peracarida with 14 099 individuals 5625 isopods 3887 amphipods 3225 tanaids 1269 cumaceans and 90 mysids copepoda 4679 ind and bivalvia 3999 ind numbers of individuals ranged between 140 at station 3 10 6383 at station 7 3 the numbers of taxa per station were smallest at station 3 10 4 taxa and highest at station 2 7 31 taxa peracarida were the most common malacostracan crustaceans recorded with isopoda comprising 40 of all peracarids within this fraction followed by amphipoda with 27 tanaidacea with 23 cumacea with 9 and mysida with 1 at station 3 10 not a single peracarid was sampled isopoda dominated most of the stations especially in the abyssal sites of the kuril basin amphipoda occurred in higher numbers in the bussol strait at site 8 as well as at pacific station 9 7 in the sokhobio area studied macrofauna was distributed very patchily in terms of diversity and composition the abyssal macrofauna of the kuril basin shows an intermediate state between the adjacent studied abyssal areas the semi isolated sea of japan and the open abyssal plain of the kuril kamchatka trench kkt area

processes controlling the distribution of ti and al in weathering profiles siliciclastic sediments and sedimentary rocks abstract the ratio of ti to al varies greatly in primary igneous source rocks these elements are considered to be relatively immobile in most weathering regimes so that tio2 al2o3 ratios have been used to investigate the provenance of sediments and sedimentary rocks in modern weathering profiles that have undergone moderate weathering ti al ratios remain fairly constant so that siliciclastic sediments derived from them should have ti al ratios like that of the source materials under extreme weathering conditions however the upper most weathered parts of profiles commonly show a marked increase in ti al ratio that is thought to be due to preferential translocation of al rich phases under steady state weathering conditions one particular level of the profile may act as the main source of detrital material and may thus control the ti al ratio of sediments produced from it in a glacio fluvial setting minimum weathering moderate sorting there is considerable variation in ti content but al is nearly constant this is due to concentration of ti bearing mafic minerals such as biotite in the fine fraction in modern sediments derived from moderately weathered and sorted material the ti al distribution reflects mixing of al and ti enriched fine grained materials with sands that are depleted in these elements when a plot of tio2 vs al2o3 is constructed for a suite of such sands and muds the resultant trend differs significantly from that shown by a similar suite of unweathered glacio fluvial sediments comparison of these results with data from sedimentary rock suites suggests that trends shown by plots of tio2 vs al2o3 may provide insight into weathering and depositional history in addition to their use as provenance indicators

orebody vertical structure and implications for ore forming processes in the xinxu bauxite deposit western guangxi china abstract the xinxu bauxite orebodies which are contained in quaternary depressions overlying strata of permian to devonian age were formed through the break up oxidation and re sedimentation of a pre existing permian bauxite horizon with progressive karsitification the underlying strata of the quaternary orebodies were eroded out downwards in sequence gradually transiting from permian to devonian thus an older underlying stratum generally infers a higher degree of weathering a total of 47 exploration wells sampled each meter were chosen from several orebodies to evaluate the vertical distribution of four major components al 2 o 3 fe 2 o 3 sio 2 and loss on ignition in the ores the vertical evenness is quantified via a box gliding multifractal model the small width of the multifractal spectrum suggests that the vertical ore quality is even overall indicating an intertwining break up and mixing up processes during evolution of the quaternary orebody although the four components show complex spatial distributions topographic elevation displays a positive relationship with the mean fe 2 o 3 content and a negative correlation with the vertical unevenness of al 2 o 3 and fe 2 o 3 in the wells this is taken to reflect the more uniform oxidizing environment in the higher depressions which facilitates a homogeneous and greater increase of fe 2 o 3 content throughout the orebody in contrast the redox conditions in lower depressions are less oxidizing and varied in space inducing great variation in degree of fe 2 o 3 increase in the ores this study also demonstrates that in the xinxu deposit the ore forming redox environment has more impact on the ore quality than the degree of weathering as the contents show irregular vertical changes in the lower depressions it follows that it is the ancient redox environment rather than the modern conditions which affect the orebody vertical structure this clarifies the fact that the vertical structure of the orebody is jointly constrained by the physical melange accumulation of ores and the differences between the ancient redox environments in the higher and lower locations these factors should be the primary factors affecting the vertical structure of karst bauxite deposits

late cretaceous coal overlying karstic bauxite deposits in the parnassus ghiona unit central greece coal characteristics and depositional environment abstract the pera lakkos coal located on top of bauxite deposits in the ghiona mining district central greece is the only known mesozoic late cretaceous coal in the country it was derived from herbaceous plants and algae growing in mildly brackish mires that formed behind a barrier system during a regression of the sea on a karstified limestone partly filled in with bauxitic detritus petrological mineralogical and geochemical data point to the predominance of reducing conditions and intense organic matter degradation in the palaeomires o c vs h c and oi vs hi plots based on elemental analysis and rock eval data characterize kerogen types i ii this reflects the relatively high liptinite content of the coal besides kerogen composition o c vs h c plot for the pera lakkos coals is in accordance with a catagenesis stage of maturation in contrast with vitrinite reflectance and t max from rock eval pyrolysis which indicate the onset of oil window maturation stage suppression of vitrinite reflectance should be considered and the high liptinite content corroborates this hypothesis despite some favourable aspects for petroleum generation presented by the pera lakkos coal its maximum thickness up to 50 cm points to a restricted potential for petroleum generation coal oxidation took place either during the late stage of peat formation due to wave action accompanying the subsequent marine transgression or epigenetically after the emergence of the whole sequence due to percolation of drainage waters both options are also supported by the ree shale normalized profiles which demonstrate an upwards depletion in the coal layer oxidation also affected pyrite included in the coal this led to the formation of acidic sulfate rich solutions which percolated downwards resulting in bleaching of the upper part of the underlying bauxite

the magnitude of late paleozoic glacioeustatic fluctuations a synthesis a comprehensive literature review shows that the magnitude of eustatic fluctuations varied throughout the carboniferous and permian and that at least eight distinct phases can be recognized facies juxtapositions in carbonate successions and erosional relief in clastic successions indicate that glacioeustatic fluctuations of 20 25 m and occasionally as much as 60 m took place throughout the early mississippian tournaisian a widely recognized glacial period middle mississippian mid chadian through holkerian shallow marine carbonate and clastic successions indicate that eustatic fluctuations were 10 25 m a decrease that matches well with the paucity of coeval glacial deposits late visean asbian through mid brigantian glacioeustatic fluctuations of 10 50 m record the initial phases of ice accumulation in advance of the widespread mid carboniferous glacial event the latest mississippian earliest pennsylvanian mid brigantian through langsettian was a time of widespread glaciation and strata of this age commonly exhibit evidence of glacioeustatic fluctuations of as much as 40 100 m although middle pennsylvanian duckmantian through asturian glacial deposits are present in eastern australia paleovalley depths suggest that coeval glacioeustatic fluctuations were less than 40 m glacioeustatic fluctuations of as much as 100 120 m have been widely reported from late pennsylvanian earliest permian stephanian through mid sakmarian successions in north america an increase that corresponds to the growth of large ice sheets across much of gondwana and the accumulation of ice in the northern hemisphere incision and facies juxtaposition in early middle permian mid sakmarian through kungurian successions in eastern australia indicate that glacioeustatic fluctuations of 30 70 m occurred during the waning stages of major glaciation erosional relief in paleoequatorial carbonates and the presence of coeval glacial deposits in australia suggests that eustatic fluctuations of 10 60 m occurred during the final stages of glaciation in the middle to late permian roadian through capitanian but the modest size of most of these fluctuations makes it difficult to isolate the glacioeustatic signature this review demonstrates that far field cyclic successions record changing glacial conditions in gondwana that the magnitude of glacioeustatic fluctuations was directly related to the volume of glacial ice that carboniferous permian glacioeustasy was more variable than previously recognized and that generalizations from short temporal intervals are probably not representative of the late paleozoic ice age as a whole although any attempt to quantify the magnitude of ancient eustatic changes is based on caveats and assumptions this review incorporates the results of over 100 published papers on the topic in an attempt to minimize the errors inherent in any one study

lateritization and bauxitization events laterites and bauxites are produced in tropical soils by weathering which enriches iron of laterites and alu mina of bauxites as well as trace elements such as nickel gold phosphorus and niobium to ore grade la terites and bauxites can be redeposited into sedimentary sequences and remain as ores if not transported far and diluted with other materials the age of redeposited laterites and bauxites and of bauxitic and lateritic pa leosols can be established from the geologic age of overlying rocks an approach especially effective in pale osols within sequences of isotopically datable volcanic rocks lateritic profiles can also be dated by paleomag netic inclination in special cases in which land masses such as in australia and india drifted long distances northward during cenozoic time in addition cryptomelane and other k mn oxides can be dated by k ar and 40ar 39ar techniques to obtain multiple ages from different crystals in a single relict paleosol compilation of new and more accurate laterite and bauxite ages reveals unusually widespread and intense laterite and bauxite formation during events of less than 100 k y duration at 2 12 16 35 48 55 65 and 100 ma such events can also be inferred at times older than 100 ma from paleolatitudinal distribution of laterites and bauxites but these are poorly sampled laterite and bauxite peaks were coeval with times of global high warmth and pre cipitation elevated atmospheric carbon dioxide oceanic anoxia exceptional fossil preservation and mass ex tinction these co2 greenhouse events and attendant titration of carbonic acid with soils are interpreted as transient fluctuations in the atmosphere produced by meteorite impact flood basalt volcanism and methane outbursts concentration of bauxite and laterite resources in particular stratigraphic horizons formed during greenhouse crises suggests the usefulness of an event stratigraphic approach to exploration and exploitation of these and related ores

trace elements and their relation to the mineral phases in the lateritic bauxites from southeast guinea bissau abstract fourteen trace elements sr ba la ca mg cu zn v ni co mn ga cr zr were determined in 120 auger and core drill samples from one bauxite plateau situated in the se part of guinea bissau following the quantitative determination of minerals identified in the samples all geochemical and mineralogical data were statistically treated the use of several statistical tools enabled us to identify two distinct populations of samples which were found to be related to the shale and dolerite parent rocks respectively the dispersion patterns of the elements mn zr la zn cu cr and ni yield strong contrasts between these two populations bauxites developed on devonian shales were found to contain more cr and ni than bauxites derived from cretaceous dolerites which were richer in cr and ni it is postulated that the difference in duration of the bauxitization processes which affected the two parent bedrocks and or the different resistance to weathering of the primary mineral host phases in the two rock types are responsible for this inversion r mode factor analysis revealed the conspicuous affinity of the mn zn ni cu co mg group and v to goethite gibbsite boehmite and anatase were found to be associated with resistate trace elements like zr and to a lesser extent cr gibbsite also reveals a certain affinity to more mobile strongly depleted elements like sr and ba the study proved the existence of numerous statistically significant correlations between the trace elements like the groups zr ti zn cu ni co mn and sr ba la