a submarine hydrothermal manganese deposit from the south west pacific island arc hydrothermal deposits of a wide variety of types are being found with increasing frequency on or near actively spreading mid ocean ridges1 4 however they also have a potential to occur in other submarine volcanic settings including island arcs5 to follow up indications of mineralization associated with submarine hydrothermal activity in the south west pacific island arc6 a joint new zealand oceanographic institute imperial college research cruise was mounted in may 1981 aboard the rv tangaroa during this cruise over 130 sampling stations were occupied at one of which were dredged manganese deposits with strong hydrothermal affinities this is the first report of such deposits from an island arc setting

comparative soil development of quaternary paleosols of the central united states abstract buried soils in the central united states aid in deciphering stratigraphy and chronology by being stratigraphic markers such soils may provide a record of many quaternary events particularly that of climatic change interglacial soils like the sangamon soil may have formed for over 100 000 years during which the climate shifted from cold to warm to cold again interstadial soils formed under cooler conditions and for less time in this paper we review our knowledge of quaternary paleosols in the central united states with emphasis on indiana and through comparison with the type localities in indiana the sangamon soil is the most widespread buried soil of interglacial rank exposures of the sangamon soil reveal a range of characteristics that are related to soil forming factors jenny h 1941 factors of soil formation mcgraw hill new york 281 pp jenny h 1980 the soil resource origin and behavior ecological studies 37 springer new york the most important of these factors include parent materials soil drainage and the duration of soil development how long a buried soil formed may be determined by whether it is an interglacial or an interstadial soil thus the sangamon soil can serve as a standard to which other soils both interglacial and interstadial can be compared the most widespread interstadial soil in the central united states is the middle wisconsinan farmdale sidney soil exposures of this soil are less common than for the interglacial sangamon soil although enough data are available to provide an additional basis for evaluation of other soils based upon a semi quantitative ranking of soil development by an assemblage of characteristics we have numerically defined soil development for well developed moderately developed and weakly developed categories the most strongly developed buried soils in the central united states are the early pleistocene soils and the yarmouth soil both the yarmouth soil and the sangamon soil may be more strongly developed in indiana than in their respective type areas in iowa and illinois both the yarmouth soil and the sangamon soil are more strongly developed than the surface soil the primary reason seems to be the greater time intervals over which the yarmouth and sangamon soils developed as expected interstadial soils are much more weakly developed than interglacial soils soil development is also a function of soil drainage in general better drained profiles of the sangamon soil are the best developed soils

the thermal history of the bowen basin queensland australia vitrinite reflectance and clay mineralogy of late permian coal measures abstract the thermal history of the bowen basin queensland australia has been investigated using vitrinite reflectance data and clay mineralogy vitrinite reflectance data combined with a study of clay mineral reactions indicates that the maximum temperatures which induced organic maturation of the bowen basin coals and extensive clay mineralisation are not related to deep burial metamorphism during the latest middle triassic earliest late triassic as previously believed the results of the present study indicate that the development of a zone of high heat flow in the latest late triassic had a major control on the thermal history of the bowen basin high palaeogeothermal gradients estimated in the northern bowen basin are interpreted to result from convective heat transfer during a hydrothermal event variable heat distributions due to localised fracture enhanced permeable zones acting as hot reservoirs in the deeper part of the basin may have been responsible for some significant local thermal anomalies in the lower coal measures the estimated palaeogeothermal gradients in the southern bowen basin also indicate high heat flow in the lower sections of the stratigraphy sections in the southern bowen basin however are believed to reflect a rock dominated semi closed system with low water rock ratio where rocks are impervious to circulating fluids and thus heat transfer may have occurred by conduction the correlation between vitrinite reflectance and clay mineralogy shows a delay in illitisation reaction relative to organic maturity for many illite smectite i s mixed layer clays in the northern bowen basin this phenomenon can be explained as a result of insufficient time for the completion of mineral reactions and a variable potassium supply in relatively impermeable rocks the relationship between i s expandability and vitrinite reflectance for the bowen basin data compared to basins with known tectonic regimes suggests a thermal history in a rift setting for the bowen basin the effect of thin igneous intrusions on clay mineral reactions is very limited intensive illitisation due to heating of intrusions can only be observed in narrow zones immediately adjacent to intrusive bodies this further demonstrates that mineral reactions are too slow to record the effect of extremely short heating duration in contrast to organic maturity indicators these differences between mineral and organic parameters aid in the identification of local contact metamorphic effects

micromorphological characteristics of a marine ferromanganese crust abstract marine ferromanganese oxide crust fragments sampled from a massive equatorial pacific ocean crust deposit exhibit distinct micromorphological features and a microchemical distribution which have not been previous reported black shiny upper layers of the crust display a prismoidal microstructure and a unique crystallite habit expressed by a mosaic like design of hexagonal and pentagonal columns this columnar arrangement which has been previously reported on a scale of a few millimeters in other marine fe mn deposits extends vertically for several centimeters and is observed throughout the entire horizontal plane of growth of the crust and is the largest scale of morphological regularity observed in marine fe mn deposits to date the polygonal columnar structures which constitute the crust are mainly composed of mn fe and ti oxides aluminium and si rich intercolumnar space lamellae surrounds individual columns and sharply defines each polyhedron additionally the chemical composition of the crust fragments exhibits an unusual uniformity over several centimeters which to our knowledge has not been previously observed in marine fe mn minerals

variations in the fine scale composition of a central pacific ferromanganese crust paleoceanographic implications a 47 to 60 mm thick fe mn crust from horizon guyot water depth 1800 1780 m central pacific was used to evaluate the potential of crusts as recorders of neogene paleoceanographic and paleoclimatic conditions the chemical composition was determined by microprobe for 16 elements from a polished thin section three analyses were made per millimeter and averaged to give the composition of each millimeter the age of the crust was determined by measuring the strontium isotope composition of the crust and comparing it with the tertiary seawater curve the crust represents 18 5 m y of growth of fe and mn oxyhydroxides the crust is composed of alternating botryoidal and laminated layers the botryoidal layers formed during the same time intervals that widespread neogene deep sea hiatuses were forming in bottom sediments the botryoidal layers represent growth during times of intensified deepwater flow whereas the laminated intervals represent more quiescent conditions the correspondence between the botryoidal layers and the neogene hiatuses is so strong that we were able to choose a variable growth rate model over a constant growth rate model for the crust chemical changes in the crust take two forms the first is represented by broad changes in the composition defined chiefly by fourth order polynomial fits to the chemical profiles of each element with depth in the crust the second is high frequency changes in composition the broader changes occurred primarily at about 15 11 5 7 4 6 4 5 2 and 4 6 ma which may correlate with major changes in paleoceanographic circulation and development of ice caps at the poles the periods of the high frequency changes may reflect climatic changes that resulted from orbital forcing these high frequency changes may correspond to the high order eccentricity periods of 3 47 2 04 and 1 31 m y

uptake of elements from seawater by ferromanganese crusts solid phase associations and seawater speciation marine fe mn oxyhydroxide crusts form by precipitation of dissolved components from seawater three hydrogenetic crust samples one phosphatized and two hydrothermal mn oxide samples were subjected to a sequential leaching procedure in order to determine the host phases of 40 elements those host phase associations are discussed with respect to element speciation in seawater the partitioning of elements between the two major phases mn oxide and fe oxyhydroxide can in a first order approximation be explained by a simple sorption model related to the inorganic speciation of the elements in seawater as has been proposed in earlier models free and weakly complexed cations such as alkali and alkaline earth metals mn co ni zn tl i and partly y are sorbed preferentially on the negatively charged surface of the mno2 in hydrogenetic crusts the driving force is a strong coulombic interaction all neutral or negatively charged chloro cd hg tl carbonate cu y pb and u and hydroxide be sc ti fe zr nb in sn sb te hf ta bi th and tl iii complexes and oxyanions v cr as se mo and w bind to the slightly positively charged surface of the amorphous feooh phase while coulombic interaction can explain the sorption of the negatively charged species the binding of neutral species is based on specific chemical interaction organic complexation of elements in deep ocean water seems to be at most of minor importance surface oxidation can explain some strong metal associations e g of co and tl with the mno2 and te with the feooh sorption reactions initially driven by coulombic forces are often followed by the formation of specific bonds between the adsorbate and the atoms of the oxide surface differences in the associations of some metals between the non phosphatized and phosphatized hydrogenetic crusts and between the hydrogenetic and the hydrothermal samples reflect the different physico chemical environments of formation and speciations in oxic seawater vs less oxic fluids especially for the redox sensitive metals such as mo and v these environmental related differences indicate that the methodology of chemical speciation used here in combination with spectroscopic methods may allow for the detection of changes in paleoceanographic conditions recorded during the several tens of millions of years of crust growth

stratigraphic control of hot fluids on anthracitization lackawanna synclinorium pennsylvania abstract the lackawanna synclinorium of pennsylvania contains abundant coal that was altered to anthracite rank during the late paleozoic alleghanian orogeny why did the coal in the synclinorium undergo anthracitization two alternatives have been suggested 1 the region was buried deeply during and or after the alleghanian orogeny and thus became hot in response to earth s geothermal gradient and 2 hot fluids migrating from the orogen toward the foreland carried heat into the coal and caused anthracitization if the second hypothesis is correct the region should contain evidence that hot fluids passed through the coal field observations illite crystallinity studies and fluid inclusion analyses indicate that the coal bearing pottsville and llewellyn formations and an underlying detachment fault called the pottchunk fault at or slightly below the base of the pottsville formation acted as a regional aquifer for the migration of hot fluids during the alleghanian orogeny the presence of quartz veins and the hydrothermal minerals tosudite and pyrophyllite in strata above the pottchunk fault and the apparent absence of an illite crystallinity burial gradient in the underlying strata suggest that fluids migrated through large pores in coarse grained sandstones through abundant fractures that developed in response to alleghanian deformation and along the pottchunk fault the quartz veins tosudite and pyrophyllite mineralization do not occur below the pottchunk fault except at one locality suggesting that fluid flow was greater above the fault perhaps because fracturing accompanying deformation increased permeability of the fault s hanging wall fluid inclusions in the pottsville and llewellyn formations indicate fluids achieved a minimum temperature of 270 c at a depth of 3 1 8 5 km heat flow calculations constrained by fluid inclusion data show the heat carried by the migrating fluids through the coal bearing strata was sufficient to elevate the rock temperature to anthracite grade conditions 250 c assuming that the fluid event lasted about 1 year thus deep burial 6 9 km of the coal bearing strata in the lackawanna synclinorium was not required for anthracitization anthracitization was likely the result of stratigraphically controlled hot fluid migration through the coal bearing strata at shallow depths 5 km

strontium isotopic compositions and paleoceanographic implication of fossil manganese nodules in dsdp odp cores leg 1 126 abstract strontium isotopic compositions of acetic acid hoac leachate fractions of eight manganese oxide deposits from the modern seafloor and of twenty one buried manganese nodules from cretaceous to recent sediments in dsdp odp cores were measured 87sr 86sr ratios of hoac leachates in all modern seafloor manganese oxides of various origins are identical with present seawater the 87sr 86sr ratios of the hoac leachates of buried nodules from dsdp odp cores are significantly lower than those of nodules from the modern seafloor and are mostly identical with coeval seawater values estimated from the age of associated sediments it is suggested that the buried nodules in dsdp odp cores are not artifacts transported from the present seafloor during the drilling process but are in situ fossil deposits from the past deep sea floor during cretaceous to quaternary periods the formation of deep sea fossil nodules prior to the formation of antarctic bottom water aabw indicates that the circulation of oxygenated deep seawaters have activately deposited manganese oxides since the eocene epoch or earlier

age determinations and growth rates of pacific ferromanganese deposits using strontium isotopes abstract 87 sr 86 sr ratios trace element and ree compositions and textural characteristics were determined for three hydrogenetic fe mn crusts one hydrothermal deposit and two mixed hydrothermalhydrogenetic crusts from the pacific the sr isotope data are compared to the sr seawater curve for the cenozoic to determine the ages and growth rates of the crusts the 87 sr 86 sr in the crusts does not increase monotonically with depth as expected if the sr were solely derived from seawater and perfectly preserved since deposition this indicates post depositional exchange of sr or heterogeneous sources for the sr originally contained in the crusts textures of hydrogenetic crusts generally correlate with sr isotopic variations the highest porosity intervals commonly exhibit the highest 87 sr 86 sr ratios indicating exchange with younger seawater intervals with the lowest porosity commonly have lower 87 sr 86 sr and may preserve the original sr isotopic ratios minimum ages of crust growth inception were calculated from dense low porosity intervals growth of the hydrogenetic crusts began at or after 23 ma although their substrates are cretaceous estimated average growth rates of the three hydrogenetic crusts vary between 0 9 and 2 7 mm ma consistent with published rates determined by other techniques within the marshall islands crust growth rates for individual layers varied greatly between 1 0 and 5 4 mm ma for one crust very low 87 sr 86 sr ratios occurred in detrital rich intervals hydrothermal fe mn oxide from the active lau basin back arc spreading axis valu fa ridge has an 87 sr 86 sr ratio with a predominantly seawater signature 87 sr 86 sr 0 709196 indicating a maximum age of 0 9 ma one crust from an off axis seamount west of gorda ridge may have begun precipitating hydrogenetically at 0 5 ma 0 709211 and had increasing hydrothermal or volcanic input in the top half of the crust indicated by a significantly lower 87 sr 86 sr ratio 0 709052

interelement relationships in ferromanganese crusts from the central pacific ocean their implications for crust genesis the fine scale chemical variations in ferromanganese fe mn crusts from the central pacific ocean were investigated using a variety of techniques in order to elucidate their genesis thirty seven major minor and trace elements were determined by icp oes and icp ms in sub samples collected at approximately 2 mm intervals throughout the crust sequences an inverse relationship is observed between the logarithm of the elemental distribution coefficients log cmncsw and the mean residence time tr of elements in seawater these associations provide evidence supporting the strong link between seawater and fe mn crust chemistry results of factor analysis reveal that elements in crusts can generally be partitioned into four major groups with selected elements displaying associations with several groups these statistical associations are interpreted to represent hydrogenetic mn ni co cu ce zn biogenic ba zn cu pt fe detrital al si fe and carbonate fluorapatite ca p ree groups a comparison between elemental associations in fine scale data from individual crust sequences and bulk compositional data from samples collected in separate locations reveals very similar elemental associations the similar elemental associations in bulk samples and in fine scale subsamples from individual crusts are consistent with the notions that hydrogenetic crusts exhibit no significant post depositional remobilization of elements and that elemental distributions within crusts reflect the chemistry of oceanic water during the period in which they accreted chemical paleotracks are proposed based on factor scores derived from chemical variations as a function of depth in individual crusts our results show that there is internal consistency between the chemical evolution previously proposed seamount paleotracks and nanofossil biostratigraphy dating results

diffusion and supply rates of 10be and 230th radioisotopes in two manganese encrustations from the south china sea ages of two mn encrustations estimated by their 230th and 10be distributions are compared with k ar ages and micropaleontological datings of their nuclei to discuss possible diffusion and supply effects of the radioisotope distribution and their influence on the reliability of age determinations based on comparable results obtained by the different methods the effective diffusion coefficient of 10be can be calculated as d 1 0 10 8cm2 y this coefficient is 3 8 times smaller than the best estimates available at present in both nodules we observe lower 10be concentrations in the uppermost 2 3 mm 1 3 m y which suggests that 10be uptake has been reduced since the middle pleistocene the 2 7 fold increase of the growth rate starting 3 2 m y ago coincides with the initiation of the northern hemisphere glaciation

stratal patterns sediment composition and sequence stratigraphy at the margin of the vercors carbonate platform lower cretaceous se france abstract conventional sequence stratigraphic concepts relate the large scale stratal architecture of sediment bodies to changes in relative sea level this paper evaluates the relationship between stratal geometry and sea level stand based on a study of large semicontinuous outcrops of cretaceous carbonate platform strata in the vercors southeastern france multiple lines of evidence for sea level change are combined including stratal geometry detailed quantitative microfacies analyses and diagenetic patterns at platform top hardground surfaces the studied outcrops of the cirque d archiane show two main prograding platform tongues both over 100 m thick the stratal geometries at the boundary between these platform tongues including an apparent pinchout of a wedge of slope sediments suggest the presence of a major lowstand unconformity however this stratal boundary does not coincide with the horizon containing the most extensive meteoric alteration furthermore detailed platform to basin correlation shows that the wedge of slope sediments is not basin restricted but makes a thin drape over the platform top the sedimentologic and diagenetic evidence suggest incipient drowning of the platform at the boundary between the two main platform tongues preceded by a minor exposure event only internally the main platform tongues consist of smaller 10 30 m thick units that prograde towards the basin and aggrade on the platform top and which are interpreted as stacked highstand wedges these wedges are usually topped by hardground surfaces with minor evidence for subaerial exposure the platform top horizon with the most extensive subaerial diagenesis and erosion correlates with a distinct but relatively thin unit of lithoclastic debris on the slope a pronounced scour in the clinoforms of the vercors does not correlate with a major exposure surface on the platform top this study shows that stratal geometries alone are a rather ambiguous guide to sea level history without the accompanying sedimentologic and diagenetic evidence for sea level change most of the stratal architecture of the vercors platform can be explained by either changes in accommodation or changes in carbonate production

basin to platform chemostratigraphy and diagenesis of the early cretaceous vercors carbonate platform se france abstract cathodoluminescence petrography has been combined with bulk rock and micro sampled 87 sr 86 sr 18 o and 13 c analyses to reconstruct the diagenetic history of lower cretaceous barremian limestones exposed at the southern margin of the vercors carbonate platform in southeastern france stratigraphic and geographic trends in these analyses coupled with mass balance water rock interaction modeling have been used to constrain the chemical composition source and relative timing of the groundwaters responsible for diagenetic alteration this study was completed on the montagnette outcrop which is composed of two stacked 70 m thick units of prograding platform margin limestones that interfinger with marly basinal sediments the montagnette exposure is exceptional in that it is a single complete outcrop of basin to platform limestones that are preserved in their original lateral depositional continuity cathodoluminescence petrography indicates that the limestones have experienced a complex sequence of carbonate dissolution precipitation and fracturing events over one hundred bulk rock and micro sampled 87 sr 86 sr 18 o and 13 c analyses were completed to characterize each major event of deposition and diagenesis bulk rock analyses from the montagnette basin to platform transect exhibited no significant variations in 87 sr 86 sr 0 707523 to 0 707555 these values are consistent with estimated barremian seawater 87 sr 86 sr ratios in contrast micro sampled shell material in the platform margin and platform top deposits exhibit large variations in 87 sr 86 sr 0 706910 to 0 707450 the least radiogenic sr lowest 87 sr 86 sr occurs in shell material located toward the platform while the more seawater like ratios occur in sections without shells that are located toward the basin this pattern implies that selective diagenetic alteration of the shell material took place after basinal brines flowed up into the platform and spread out laterally the sr in the diagenetic waters was probably derived from water rock interaction with jurassic basinal sediments in the vocontian trough this conclusion is based on 1 the extremely low 87 sr 86 sr composition of shell material in the platform limestone 2 modeled co variation trends in 87 sr 86 sr 13 c and 18 o and 3 the absence of another nearby source of less radiogenic sr in the vercors region

calcareous nannofossil biostratigraphic dating of a ferromanganese crust from schumann seamount abstract calcareous nannofossil biostratigraphy was employed to determine the age and growth rates of the different layers within ferromanganese crusts from schumann seamount 200 miles north of the island of kauai hawaii this work is part of a study to reconstruct the paleoceanographic history of crusts using various geochemical indicators the methods are based on the identification of coccolith imprints not actual coccolith remains age constraints on the time span of a particular horizon are defined either 1 by the presence of a species which was extant for only a limited geological time interval or 2 by the presence of two organisms whose time ranges overlapped age resolution is optimized by short time ranges or narrow overlaps in the crust studied there was considerable inter horizon variability in the preservation of coccolith imprints in imprint abundance and in species diversity some of the crust layers examined were narrowly constrained temporally 1 4 myr while others were less so 10 myr our results indicate that the minimum age for the interval at 27 mm depth is at least eocene this is the maximum age many believe any crust can be the position of this interval however is only about one half of the way through the crust while the data support previous estimates of average crust growth rates 0 5 mm myr the actual apparent growth rate appears to have varied by an order of magnitude 0 1 to 2 mm myr

effects of phosphatization on the geochemical and mineralogical composition of marine ferromanganese crusts most hydrogenetic ferromanganese crusts in the central pacific consist of two growth generations a phosphatized older growth generation that is impregnated with carbonate fluorapatite cfa and a younger non phosphatized growth generation geochemical and mineralogical investigations of non phosphatized and phosphatized crust layers revealed significant differences that are not simply dilution effects by cfa certain elements are depleted in old crusts compared to young crusts in the order si fe al ti co mn pb others like ni zn cu y and rees rare earth elements are mostly enriched suboxic conditions in the phosphate rich water of the oxygen minimum zone that infiltrated the crusts caused a partial redissolution of crust phases resulting in mobilization of associated elements a partial recrystallization of more stable phases and a secondary input of nutrient type elements the frequent occurrence of todorokite in phosphatized crust layers indicates that mn mobilized from the vernadite crust phase was partially recrystallized as todorokite which is more stable under suboxic conditions incorporating ni cu and zn into the crystal lattice but rejecting co other metals like pb y and rees probably form stable phosphate phases in phosphatized crusts our investigations emphasize that under the influence of phosphatization diagenetic remobilization and reorganization in fe mn crusts took place in contrast to non phosphatized crusts the older phosphatized crust generation no longer represents a complete primary crust precipitate therefore young non phosphatized and old phosphatized crust generations should be considered as two different sample types with respect to geochemical composition mineralogy and evolution we also suggest that most methods for age determination like the 87sr86sr isotopic dating method or co chronometry cannot be used for phosphatized crusts without caution

sr and nd isotopic variations in ferromanganese crusts from the central pacific implications for age and source provenance abstract isotopic analyses of two hydrogenetic ferromanganese fe mn crusts from volcanic edifices in the central pacific ocean reveal systematic variations in 87 sr 86 sr and 143 nd 144 nd with both ratios decreasing as a function of depth into the fe mn crusts leaching experiments suggest that sr in the crusts is contained in at least two discrete sites a loosely bound sr dominated by modern marine sr is removed by leaching with a 10 percent acetic acid solution the 87 sr 86 sr ratio of the residue is significantly less than the 87 sr 86 sr ratio of the unleached material the sr isotope ratios of leached samples are compared with the temporal variation in seawater to provide ages for layers within the fe mn crusts these data suggest that the oldest crust layers began to accrete in the early to middle miocene correlated to the 87 sr 86 sr variations 143 nd 144 nd ratios suggest that the nd isotope composition of central pacific ocean seawater also changed systematically over this time interval or that the fe mn crusts simply incorporated nd from various parts of an isotopieally heterogeneous ocean as the crusts were carried along with the oceanic plate in contrast to the layered ferromanganese crust the phosphatized volcaniclastic substrates have sr and nd isotope compositions that are consistent with their volcanic origin

distribution of thorium 232 in manganese nodules and crusts paleoceanographic implications detailed depth profiles of 232th in deep sea ferromanganese nodules and encrustations often show a subsurface maximum followed by a drastic inward decrease to a certain depth before levelling out length scales of this feature vary among the profiles but are proportional to growth rates of the specimens suggesting that the profiles record changes in oceanic 232th flux with time consideration of the nodule chronology the history of eolian accumulation recorded in sediment cores and the marine geochemical behavior and budget of 232th leads us to propose that 232th in nodules crusts is of eolian origin the drastic inward decrease of 232th is a reflection of increase in the wind borne dust flux induced by the northern hemisphere glaciation beginning 2 3 ma the subsurface 232th peak may indicate the decline of eolian flux since 0 1 0 3 ma

paleoceanographic implications of rare earth element variability within a femn crust from the central pacific ocean abstract results of detailed geochemical analyses of thick fe mn oxide crust accumulations from the central pacific ocean lead to the suggestion that variations in their chemical composition and microstructure reflect the influence of prevailing environmental conditions at the time of formation of the deposit these findings imply that well preserved fe mn crusts represent a geologic record that may extend back to the onset of fe mn oxide precipitation on the subsrtate material current crust growth rate estimates of 1 3 mm m y imply that 6 10 cm thick fe mn oxide accumulations represent a growth record of 20 to a maximum of 100 m y detailed chemical and mineralogical analyses were performed on successive hand picked layers of a 95 mm thick fe mn crust recovered from schumann seamount in the hawaiian archipelago the analyses reveal significant variations in the elemental distribution and abundance of major constituents and rees as a function of depth within the crust the trivalent rees generally exhibit sympathetic concentration changes in pure fe mn oxides but the fractionation observed between the light and heavy rees differs in layers enriched in phosphatic matter the compositional variability and the extent of ree fractionation can be explained in large part by mineralogical control but can also be inferred to reflect differing depositional conditions in the seawater from which the deposits formed variations in the ce anomaly and ree fractionation patterns within the individual layers of the crust are related to their major element composition and mineralogy and to the anomalies observed by other workers these are used to attempt to reconstruct the growth history of the crust

10 be dating of a manganese crust from central north pacific and implications for ocean palaeocirculation one of the most promising applications of the new 10be detection technique using accelerator mass spectrometry is the determination of growth rates of mn nodules and crusts1 5 because the half life of cosmogenic 10be 1 5 myr is of the same order as the time needed for a few millimetres of nodule material to grow 10be is a useful tool for unravelling such evolution during the late tertiary when most nodules are assumed to have started their growth6 mass spectrometric measurement of a 10be profile across the manganese crust va 13 2 from the central pacific using a tandem van de gr a ff accelerator yields growth rates of 2 7 and 4 8 mm myr 1 for the layers of the crust accumulated between recent and 6 myr bp and between 6 and 11 myr respectively using these measurements as well as 230th dating we have been able to distinguish boundaries between zones in the crust with different structures and chemical compositions and to assign ages to them these ages are 0 12 2 9 3 4 5 7 6 7 7 9 10 12 and 13 16 myr bp all of these boundaries apparently coincide with the times reported for quaternary and late tertiary palaeoclimatic events suggesting that the crust growth has been strongly influenced by palaeoclimate

spatial variation of u th series radionuclides and trace metals in deep sea manganese encrustations abstract a series of measurements to assess the spatial variability on a scale of a few centimeters of u th series nuclides and trace metals in surface layers of deep sea ferromanganese encrustations are reported here two samples one from an atlantic seamount and another from manop site s in the pacific are reported the inventories of230thexc cm 2 and231paexc cm 2 as well as the ratios of the inventories are seen to vary by large amounts in samples only a few centimeters apart these observations infer that the fluxes of these radionuclides to small areas on the ferromanganese crust may also vary with time no strong correlation between the radioisotope inventories and concentrations of various elements has been observed

incorporation of be isotopes and other trace metals into marine ferromanganese deposits abstract two to threefold inward increase of 10be 9be cu and ni have been found in surface layers of marine ferromanganese deposits we interpret this phenomenon as reflecting the manner in which the be isotopes and probably other trace metals e g cu and ni are incorporated on reaching the sea floor exchangeable be is released from its carrier phase to the pore water of the ferromanganese deposits diffuses inward and gets fixed into the deposits the fixation process may be related to the mineralogical reorganizations suggested by previous studies we have modeled this concept and applied it to a mn crust on which detailed analyses of cu ni and natural decay series nuclides as well as be isotopes are made post depositional fixation of th isotopes may also occur the redistributions of be and th isotopes are confined to regions very close to the surface of the deposits for all practical purposes they will not affect growth rate determinations conventionally done using these isotopes the linearly extrapolated 10 be 9 be ratio to the surface from deep layers of a mn deposit does not necessarily represent that ratio in sea water

constancy of oceanic deposition of 10 be as recorded in manganese crusts recent developments in the use of nuclear accelerators as high energy mass spectrometers1 2 has renewed interest in the study of cosmogenic 10be half life 1 5 myr as a geophysical time tracer the accelerator techniques enable us to measure 10be with a sensitivity of 107 atoms or less the potential age dating span with 10be is extended back to at least 15 myr bp providing that the 10be production and deposition rates remain constant or nearly constant over that time period a knowledge of the long term constancy in the 10be deposition rate is thus very important we report here the first detailed measurements of 10be and 9be in two ferromanganese oxide crusts from the sea floor of the equatorial atlantic sample no k 9 21 and the north pacific schw 1d each representing 10 myr of accumulation history we have found in these crusts that the deposition of 10be and 10be 9be during the past 7 9 myr has been constant averaged over time intervals of 1 myr the variation is within 6 before that time both crusts show similar significant deviations the 7 9 myr demarcation may be related to the reported late miocene global abyssal circulation change in the ocean3

hawaiian submarine manganese iron oxide crusts a dating tool black manganese iron oxide crusts form on most exposed rock on the ocean floor such crusts are well developed on the steep lava slopes of the hawaiian ridge and have been sampled during dredging and submersible dives the crusts also occur on fragments detached from bedrock by mass wasting on submerged coral reefs and on poorly lithified sedimentary rocks the thickness of the crusts was measured on samples collected since 1965 on the hawaiian ridge from 140 dive or dredge localities fifty nine 42 of the sites were collected in 2001 by remotely operated vehicles rovs the thinner crusts on many samples apparently result from post depositional breakage landsliding and intermittent burial of outcrops by sediment the maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site the measurements show an irregular progressive thickening of the crusts toward the northwest i e progressive thickening toward the older volcanic features with increasing distance from the hawaiian hotspot comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust growth rate of about 2 5 mm m y the thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes but also provides specific age estimates of volcanic and landslide deposits the data indicate that some of the landslide blocks within the south kona landslide are the oldest exposed rock on mauna loa kilauea or loihi volcanoes crusts on the floors of submarine canyons off kohala and east molokai volcanoes indicate that these canyons are no longer serving as channelways for down slope sediment laden currents mahukona volcano was approximately synchronous with hilo ridge both being younger than hana ridge the nuuanu landslide is considerably older than the wailau landslide the waianae landslide southwest of oahu has yielded samples with the greatest manganese iron oxide crusts 9 5 mm thick and therefore apparently represents the oldest submarine material yet found in the study area the submarine volcanic field 100 km southwest of oahu is apparently younger than the waianae landslide

an integrated cathodoluminescence video capture microsampling system a new system is described that permits real time microdrilling of sedimentary grains and crystals within cathodoluminescence zonations low light cathodoluminescence photomicrograph images are captured with a thermoelectrically cooled color video camera and saved on a computer these cathodoluminescence images are then transparently superimposed on a standard color video image of the sample being microdrilled on a 20 m scale using a video mixer this integrated system can be applied to a wide variety of sedimentary rocks and minerals

modeling subsurface flow in sedimentary basins groundwater flows that arise in sedimentary basins from the effects of topographic relief buoyant convection sediment compaction erosional unloading and combinations of these driving forces can be described using quantitative modeling techniques models can be constructed to consider the effects of heat and solute transport petroleum migration and the chemical interaction of water and rocks the accuracy of model predictions however is limited by the difficulty of predicting hydrologic properties of sediments on regional dimensions estimating past conditions such as topographic relief and knowledge of how physical and chemical processes interact over gelogic time scales progress in basin modeling will accelerate as hydrologic research efforts are better integrated with those of other specialities such as sedimentology rock mechanics and geochemistry

the association between tectonic deformation inorganic composition and coal rank in the bituminous coals from the south wales coalfield united kingdom analysis of vertical distribution of coal rank in three collieries and one opencast mine in the se of the south wales coalfield has revealed deviations from hilt s law in both proximate analyses and in vitrinite reflectance the variations in rank parameters studied are closely correlated with variations in the intensity of tectonic deformation measured using a numerical deformation index ndi three seams in the sequence were also analysed for major and trace element geochemistry and rock eval pyrolysis variations in these parameters are related to thrust inclusion of floor and or roof mudrocks into the seams a detailed conceptual model of a major thrust and associated in seam thrust detachments and lag faults is developed to explain the vertical rank profile by post coalification faulting it is concluded that although the model can explain the vertical pattern of rank the complexity of the required faults render the model improbable the alternative mechanisms for enhancement of the rank parameters associated with tectonic deformation including shear stress control frictional heating and localised fluid flow are discussed and are thought more likely to be responsible for the deviations from hilt s law in the vertical rank profile rank suppression shown by three seams two of which are overlain by marine bands is thought to be related to biochemical activity in the peat environment resulting from the influx of saline waters

formation of ferromanganese crusts on northwest intertropical pacific seamounts electron photomicrography and microprobe chemistry abstract seven ferromanganese crusts from the northwest intertropical pacific seamounts were analyzed for photomicroscopic growth structures microprobe chemistry and ages based on co chronometer growth rate the crusts on the marshall islands seamounts are thick and are divided into phosphatized lower older and nonphosphatized upper younger growth generations the older crust consists of compact laminations and columns impregnated with carbonate fluoapatite cfa whereas the younger crust is characterized by porous botryoids and columns of mno2 and fe oxyhydroxide the crusts on the federated states of micronesia fsm and palau islands seamounts are thin and are often incorporated with inorganic opal a in the uppermost part comprising the younger generation some crusts show scours and fractures although the growth of crusts has been often interrupted by mass failure of slope sediments the crusts on the marshall islands seamounts are estimated to have grown at rate of about 3 mm ma since the middle eocene and to have been phosphatized in the late oligocene during the host seamounts were located beneath the equatorial zone of high productivity prolonged infiltration of the oxygen minimum zone omz water into shallower water older crusts redistributed crust composition by precipitating cfa enriching subsequent amounts of mn and ni and removing some co the younger crust has formed at slower rate about 2 mm ma under the stronger influence of bottom water circulation in the north of the equatorial zone concentrating abundant co in the uppermost part of some crusts siliceous skeletons transform with burial to inorganic opal a and si rich fe oxyhydroxide suggesting that biosilica diagenesis can enhance crust growth

cenozoic accumulation history of a pacific ferromanganese crust to investigate the growth rates and absolute time stratigraphy of marine hydrogenetic ferromanganese encrustations we performed 10be profiling and co chronometry of crustal layers as well as 87sr86sr and 18o analysis of phosphatised limestone francolite within a 9 5 cm thick ferromanganese crust from schumann seamount in the hawaiian archipelago together with microfossil stratigraphy our results indicate that some seamount crusts greatly exceed the commonly accepted miocene maximum age in this case probably approaching the cretaceous age of the seamount in addition to the unconformity at the crust substrate boundary at least eight major disconformities are indicated in the schumann seamount crust which probably represent depositional hiatuses or episodes of crust erosion three of the six upper disconformities can be placed at the plio pleistocene middle miocene and paleocene eocene based on 10be microfossil and co chronometer evidence 87sr86sr and 18o values of purified francolite from an inclusion rich layer between the depths of 44 and 49 mm suggest apparent ages that approach those of eocene late paleocene microfossils reported in overlying layers whereas francolite vein infillings in the lower part of the crust and in the basaltic substrate yield values that if interpreted as ages of phosphatization suggest a minimum oligocene age paleotracking suggests the phosphogenesis observed here and on other central pacific seamounts could not have resulted from upwelling enhanced productivity associated with equatorial divergence if the oligocene and middle miocene isotopic ages reported here and elsewhere are correct however a maximum late paleocene age for the phosphogenesis consistent with the stratigraphy would place these seamounts within 10 n of the equator paleotracking also suggests northeast tradewind transport of aluminosilicates in the cenozoic in agreement with other evidence for the antiquity of this ferromanganese crust

rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments abstract analyses have been made of ree contents of a well characterized suite of deep sea 4000 m principally todorokite bearing ferromanganese nodules and associated sediments from the pacific ocean ree in nodules and their sediments are closely related nodules with the largest positive ce anomalies are found on sediments with the smallest negative ce anomalies in contrast nodules with the highest contents of other rare earths 3 ree are found on sediments with the lowest 3 ree contents and vice versa 143 nd 144 nd ratios in the nodules 0 51244 point to an original seawater source but an identical ratio for sediments in combination with the ree patterns suggests that diagenetic reactions may transfer elements into the nodules analysis of biogenic phases shows that the direct contribution of plankton and carbonate and siliceous skeletal materials to ree contents of nodules and sediments is negligible inter element relationships and leaching tests suggest that ree contents are controlled by a p rich phase with a ree pattern similar to that for biogenous apatite and an fe rich phase with a pattern the mirror image of that for sea water it is proposed that 3 ree concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate processes which favour the enrichment of transition metals in equatorial pacific nodules favour the depletion of 3 ree in nodules and enrichment of 3 ree in associated sediments in contrast ce appears to be added both to nodules and sediments directly from seawater and is not involved in diagenetic reactions

hydrothermal alteration in anthracite from eastern pennsylvania implications for mechanisms of anthracite formation orthogonal joint sets cleat in anthracite rank coal beds from eastern pennsylvania contain two mineralogically and chemically different authigenic clay mineral assemblages in localities from all four anthracite fields the systematic cleat contains significant quantities 20 to 95 wt of authigenic rectorite sudoite or tosudite which are clay minerals primarily associated with hydrothermal veins and ore deposits the strike of systematic cleat in this region roughly parallels the inferred direction of lateral compressive stress during the alleghany orogeny the opposing nonsystematic cleat contains mostly authigenic nh 4 illite a clay that also occurs in the coal matrix all of these authigenic clay minerals formed during anthracitization t 200 c by replacement of kaolinite and quartz both of which formed during an earlier stage of coalification and are present in the joints and matrix of nearly all coal samples these distinct mineralogical structural relations are observed throughout the anthracite region and suggest that 1 mineralogical variations in the coal joints are related primarily to permeability variations that were controlled by the orientation of alleghanian stress fields 2 hydrothermal fluids passed through the systematic cleat during anthracitization and 3 hydrothermal alteration influenced diagenesis in this region hydrothermal alteration may be related to basin wide fluid migrations that were driven by alleghanian age uplift basinal fluid flow concentrated along permeable joints and detachment zones could have efficiently transported heat from depth and thereby increased the rate of coalification and decreased the postulated minimum depths at which anthracitization occurred perhaps 5km vs 6 10 km

an evaluation of strontium isotopic dating of ferromanganese oxides in a marine hydrogenous ferromanganese crust abstract in order to assess the utility of dating marine hydrogenous ferromanganese crusts with strontium isotopes we conducted a series of leaching experiments on samples selected from several stratigraphic layers of a well preserved 9 5 cm thick crust from the pacific ocean initially using a method similar to that of previous studies acetic acid leached residues of twelve subsamples were leached with hcl and the leachates analyzed for their isotopic composition the results did not make stratigraphic sense so we carried out two sequences of more detailed leaches on subsamples from four layers representing the chemical and textural spectrum observed in the crust in one sequence mineral specific leaches were selected for optimal extraction of strontium associated with the respective manganese and iron oxide phases the main compositional endmembers within ferromanganese crusts strontium isotopic ratios for these leaches were compared with those from the other sequence involving acetic acid plus hcl leaches on the same material residues remaining at the end of each leaching sequence were also analyzed it is evident from the results that hcl extracts strontium associated with both phosphatic material and aluminosilicate detritus present within the ferromanganese layers 87 sr 86 sr ratios obtained on the manganese oxides indicate that the strontium within the oxides exchanges with seawater strontium throughout the history of the deposit regardless of the porosity of the layer assuming that this crust is representative of other marine hydrogenous crusts strontium isotopes appear to be of little value for the direct dating of ferromanganese oxide deposits

magnetostratigraphy of hydrogenetic manganese crusts from northwestern pacific seamounts abstract fine scale dating is crucial to understanding the growth and environments of formation of marine manganese deposits the paleomagnetic method of dating of manganese nodules and crusts has been attempted but with no success so far we measured remanent magnetization rm on up to 75 mm thick hydrogenetic crusts at intervals of 2 5 mm after mineralogical and chemical examination careful separation and alternative field demagnetization stable sharp rm and well correlated polarity change patterns between four samples made it possible to identify the pliocene quaternary magnetic chrons in them these data show that the three crusts have grown continuously at rates of 14 17 mm m y since the early pliocene this is three or four times faster than those for central pacific seamount hydrogenetic crusts estimates of growth rate based on determination of co flux are within this range magnetostratigraphy therefore appears to be a powerful method for dating hydrogenetic manganese crusts when supported by conventional dating methods these results encourage finer scale investigations which promise more detailed paleoceanographic reconstruction

evidence for stratigraphically controlled paleogeotherms in the illinois basin based on vitrinite reflectance analysis implications for interpreting coal rank anomalies coal rank reflects the temperature of coalification with higher rank coal forming at higher temperatures if the temperature of coalification depended only on the earth s geothermal gradient then the maximum rank of coal in a sedimentary basin should be directly proportional to the thickness of strata above the coal this association does not occur in the illinois basin a continental interior basin in the midwestern united states where the overall coal rank observed is higher than can be explained by past burial depth alone recognition of this anomaly has led many authors to suggest that hot groundwater flowing from south to north during a paleozoic basin scale groundwater migration event increased coal rank we analyzed vitrinite reflectance formula 1 a measure of rank as a function of depth in wells across the basin to determine how paleogeotherms representing variation in temperature with depth change with location our results show that the basin can be divided into three zones 1 in the southern zone the paleogeotherm varies irregularly with depth in strata above the sub absaroka unconformity the contact separating pennsylvanian and mississippian strata 2 in the central zone the paleogeotherm displays a distinct inflection at the unconformity for the rate of increase in formula 2 with depth is greater above the unconformity than below the unconformity and 3 the observed inflection in the paleogeotherm dies out northward until in the northern zone the paleogeotherm has the same slope both above and below the unconformity we propose that the inflection in the paleogeotherm of the central zone indicates that the hot groundwater responsible for causing an increase in coal rank flowed through a high permeability zone just below the sub absaroka unconformity this flow which advected heat into pennsylvanian strata above cooled as it moved northward so it did not influence the paleogeotherm in the northern zone preliminary studies of vein paragenesis stable isotope composition and fluid inclusions as well as computer modeling of flow related heat advection support this proposal 1 embed mml math 1 gif 2 embed mml math 2 gif

distribution of rees and yttrium among major geochemical phases of marine fe mn oxides comparative study between hydrogenous and hydrothermal deposits abstract mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the andaman sea have been investigated with special reference to the solid phase partitioning behavior of rare earth elements rees bulk elemental compositions indicate that the oxides from a volcanic cratered seamount csm are hydrothermal while those from another seamount sm2 are hydrogenous in origin the distributions of rees and yttrium in four geochemical phases viz easily exchangeable mn oxide fe oxyhydroxide and residual of csm oxides were distinctly different from that of sm2 oxides in csm oxides the rees and yttrium are mainly associated with fe oxyhydroxide phase while in sm2 oxides both mn oxide and fe oxyhydroxide phases contain the major fraction of these elements the exchangeable and residual phases of both hydrothermal and hydrogenous oxides have extremely low ree content the shale normalized negative ce anomalies and relative enrichment of heavy ree characteristic of hydrothermal oxides are retained in fe oxyhydroxide phase in hydrogenous oxides the positive ce anomalies occurred in both fe and mn oxide phases while negative y anomalies were found only in fe oxyhydroxide phase the phase distribution of rees and yttrium in hydrothermal oxides is described in terms of co precipitation and adsorption of their halide complexes and available free ions in hydrothermal solutions instead adsorption of major carbonate species from seawater primarily regulates the partitioning of rees among the co existing phases of hydrogenous oxides