classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

paleoclimatic significance of the stratigraphic occurrence of photosynthetic biomarker pigments in the nordic seas sedimentary chlorins and porphyrins are diagenetic products of chlorophyll molecules and are considered to be chemical fossils or biomarkers of phototrophic organisms the stratigraphic occurrence of such components was investigated in four cores from the nordic seas that span the last deglacial period the presence of chlorins in all the samples deposited during the younger dryas and at the end of the last glacial period indicated that photosynthetic activity occurred during these cold episodes and hence that ice free conditions existed at least seasonally in the nordic seas vanadyl porphyrins were found in sediments deposited during termination ia in only two of the cores close to the barents shelf we argue that they derive from erosion and advection of organic rich deposits as ice rafted debris during melting of the barents ice sheet thus we suggest that the sedimentary occurrence of vanadyl porphyrins in nordic sea cores can be used as a marker of ice rafted debris from the barents ice sheet the absence of such components during termination ib indicates that the complete destruction of the barents ice sheet took place during the first stage of the deglaciation

seasonal variability of the long chain alkenone flux and the effect on the u37k index in the norwegian sea a seasonally varying sedimentation pattern was observed for the alkenone flux measured with sediment traps in the northern north atlantic in the norwegian sea traps were set at 500 1000 and 3000 m the alkenone flux varied between 0 1 and 7 1 g m 2 d 1 and followed the seasonal pattern of the bulk parameters maximum fluxes occurred from mid october until mid november and were also high in may a surprising result was that considerably higher particle fluxes were observed at 3000 m for the alkenone flux the highest additional input of 250 was observed during the period when sediment resuspension was greatest in summer at the barents sea continental margin traps at 1840 and 1950 m the alkenone fluxes follow the sedimentation pattern of the bulk parameters with a less visible signal of distinct seasonality observed in the 1950 m trap the sedimentation of total alkenones varied between 0 8 and 144 g m 2 d 1 at 1840 m and between 0 5 and 31 0 g m 2 d 1 at 1950 m resuspension and lateral advection contributed significantly to measured fluxes in the two near bottom traps alkenone concentrations were determined in faecal pellets of appendicularia ostracods and euphausids from selected samples at the barents sea site the alkenone flux in pellets 4 to 24 of total was 5 to 6 times higher at 1950 m depth than at 1840 m and the major part 77 78 of the total flux of c37 3 reaching the near bottom trap at 1950 m was associated with faecal pellets of the meso zooplankton spatial and temporal variations of the u37k signals were observed indicating that the imprint in the alkenone signal depends on the origin and transport pathway of the organic material strong deviations occur in areas where nepheloid layers contribute particles of long residence times to the primary flux

depth ranges of alkenone production in the central pacific ocean we report analytical results of long chain c 37 c 39 alkenones in the surface sediments taken along a latitudinal transect at 175 e from 48 n to 15 s unsaturation degree of c 37 alkenones u k 37 indicated that alkenone temperature is the highest about 28 3 c in the tropical pacific and decreases toward 48 n about 10 1 c although the latitudinal trend of the alkenone temperature is generally similar to that of the observed sea surface temperature of the surface mixed layer the former exhibits markedly lower values than the latter does in the midlatitude 35 19 n on the basis of the comparisons between water column temperatures and alkenone temperatures in the surface sediments we estimated that in the midlatitudes alkenones are produced in the thermocline waters whereas in the high 48 40 n and low 10 n 2 s latitudes they are produced in the surface mixed layer this result is supported by the depth distribution of emiliania huxleyi and gephyrocapsa oceanica along a 155 w transect in the central pacific the latitudinal distribution of the alkenone production layers estimated from u k 37 is found to be consistent with that of the nitrate suggesting that the depth of alkenone production is mainly controlled by the nutrient supply from deeper waters alkenones in the sediments exhibited relatively large abundances in 43 27 n with a maximum at 30 n which may be explained by high productivity of haptophyte algae in kuroshio extension

a reexamination of northeast atlantic sea surface temperature and salinity over the last 16 kyr we present a 15 kyr sea surface temperature sst record for a high sedimentation rate core knr51 29ggc from the feni drift off of ireland based on an organic geochemical technique for paleotemperature estimation u37k we compare the u37k temperature record to planktonic foraminiferal 18o and foraminiferal assemblage sst estimates from the same sample horizons u37k gives sst estimates of 13 c for the early deglacial and 18 c for the holocene and recent whereas assemblages give estimates of 9 c and 13 c respectively as in nearby core v23 81 we find ash zone 1 the younger dryas increase in neogloboquadrina pachyderma sinistral abundance and maximum abundance of this species during glaciation n pachyderma dextral oxygen isotopic analyses have a late glacial to interglacial range of 1 5 a reduction of about 1 in 18o occurred at about 12 ka whereas u37k and the foraminiferal fauna indicate a 2 c warming this implies a 0 9 salinity effect on 18o which we attribute to meltwater freshening all three parameters indicate cooling during the younger dryas u37k sst estimates show that the major shift from deglacial to interglacial temperatures occurred after the younger dryas in termination 1b in contrast to the assemblage data which show this jump in sst at the end of the glaciation during termination ia differences between the two sst estimators which may result from their different floral versus faunal sources are more pronounced between transitions ia and ib this may reflect different habitats under the unusual sea surface conditions of the deglaciation

long chain alkenones and alkyl alkenoates as palaeotemperature indicators their production flux and early sedimentary diagenesis in the eastern north atlantic the production and fate of long chain alkenones and alkenoates was examined with regard to their use as palaeotemperature indicators alkenoate abundances were higher than previously reported for other regions and more strongly correlated with temperature than was alkenone unsaturation u37k suggesting biogeographical variability in alkenone and alkenoate production in surface waters we define the aa36 ratio to parameterize alkenoate abundance and present an empirical temperature calibration derived from our euphotic zone samples for use in the north atlantic t 17 35 25 12 u37k 26 73 aa36 93 90 u37k aa36 significant diagenetic losses of alkenones and alkenoates were found within the water column and near surface sediments in spite of diagenetic losses the temperature signal recorded by these compounds in the sediments remains largely unaltered and corresponds to the euphotic zone water temperature during the springtime period of maximum coccolithophorid production and flux rather than the average annual sea surface temperature

detection of natural weathering of upper mcalester coal and woodford shale oklahoma u s a abstract natural weathering refers to the natural oxidation of organic and inorganic matter in rocks at the surface and in the shallow subsurface the objective of this study is to apply routine geochemical analyses including organic petrography to coal and shale samples extending from the weathered to unaltered zones to illustrate the effects of weathering on organic matter in coal and shale some significant observations from the upper mcalester coal and the woodford shale are 1 a sulfate index si using sulfur form analysis data that reveals the transformation of pyrite to sulfate minerals is a very sensitive weathering indicator it increased in weathered samples 2 rock eval pyrolysis data such as hydrogen index hi and oxygen index oi are very sensitive to weathering oi hi increased in weathered samples 3 vitrinite reflectance decreased in weathered samples and 4 petrographic signs of weathering include microfractures pitted surface dark reaction rims and high relief sulfate index and petrographic signs of weathering should be used on surface and shallow subsurface rock samples as an indication of the extent of weathering the validity of other analyses can then be evaluated accordingly

development of web based organic petrology photomicrograph atlases and internet resources for professionals and students abstract with advances in web applications organic petrography and other related disciplines are in need of updated online resources and educational tools to aid professionals and students in the identification and interpretation of macerals the u s geological survey usgs organic petrology laboratory along with usgs eastern energy resources science center information technology staff have developed five web atlases containing images of organic matter in geologic materials 1 an american society for testing and materials astm atlas 2 an organic petrology taxonomy for international classification optic of coal macerals atlas 3 an interactive gulf coast photomicrograph web atlas i map 4 an organic material in shales atlas shale and 5 an interactive blue white ultraviolet uv light atlas light each web atlas contains images of macerals with associated sample and petrographic data collected by the usgs these webpages will provide means to preserve and circulate petrographic data collected by the usgs for coal and shale samples from all over the world

organic petrology and geochemistry of eocene suzak bituminous marl north central afghanistan depositional environment and source rock potential abstract organic geochemistry and petrology of eocene suzak bituminous marl outcrop samples from madr village in north central afghanistan were characterized via an integrated analytical approach to evaluate depositional environment and source rock potential multiple proxies suggest the organic rich toc 6 wt bituminous marls are immature for oil generation e g vitrinite ro 1 indicating organic input from marine algae and or bacterial biomass and sterane hopane ratios are low 0 12 0 14 monoaromatic steroids are dominated by c28 clearly indicating a marine setting high gammacerane index values 0 9 are consistent with anoxia stratification and may indicate intermittent saline hypersaline conditions stable c isotope ratios also suggest a marine depositional scenario for the suzak samples consistent with the presence of marine foraminifera including abundant planktic globigerinida and rare benthic discocyclina and nummulites biomarker 2 methylhopane for photosynthetic cyanobacteria implies shallow photic zone deposition of madr marls and 3 methylhopane indicates presence of methanotrophic archaea in the microbial consortium the data presented herein are consistent with deposition of suzak bituminous marls in shallow stratified waters of a restricted marine basin associated with the southeastern incipient or proto paratethys geochemical proxies from suzak rock extracts s content high polar content c isotopes normal r c27 29 steranes and c29 c30 and c26 c25 hopane ratios are similar to extant data from paleogene oils produced to the north in the afghan tajik basin this observation may indicate laterally equivalent strata are effective source rocks as suggested by previous workers however further work is needed to strengthen oil source correlations

tropical sea surface temperatures during the last glacial period a view based on alkenones in indian ocean sediments abstract the quantification of tropical temperatures during the last glacial cycle 0 150 kyr bp is a controversial issue since different proxies seem to provide conflicting informations to obtain a complementary point of view we use the alkenone method to estimate sea surface temperatures and focus our work on deep sea sediments recovered from the tropical indian ocean we present alkenone data obtained in two cores which cover in detail the last deglaciation and in about twenty cores distributed between 20 s and 20 n that were chosen to evaluate the temperature contrast of the last glacial interglacial transition our results indicate that indian ocean tropical temperatures remained an average within 1 5 2 5 c of their present values during the last glaciation at 10 n the last deglaciation is characterized by two warming steps which is similar to the classical deglacial chronology observed in the north atlantic area at 20 s the deglacial warming occurred at ca 15 cal kyr bp lagging significantly 5 4 kyr behind the antarctic warming but in phase with northern hemisphere time series

an organic geochemical assessment of oceanographic conditions at manop site c over the past 26 000 years eleven sediment samples taken downcore and representing the past 26 kyr of deposition at manop site c 0 57 2 n 138 57 3 w were analyzed for lipid biomarker composition biomarkers of both terrestrial and marine sources of organic carbon were identified in general concentration profiles for these biomarkers and for total organic carbon toc displayed three common stratigraphic features in the time series 1 a maximum within the surface sediment mixed layer 4 ka 2 a broad minimum extending throughout the interglacial deposit and 3 a deep pronounced maximum within the glacial deposit using the biomarker records a simple binary mixing model is described that assesses the proportion of terrestrial to marine toc in these sediments best estimates from this model suggest that 20 of the toc is land derived introduced by long range eolian transport and the remainder is derived from marine productivity the direct correlation between the records for terrestrial and marine toc with depth in this core fits an interpretation that primary productivity at site c has been controlled by wind driven upwelling at least over the last glacial interglacial cycle the biomarker records place the greatest wind strength and highest primary productivity within the time frame of 18 to 22 kyr b p diagenetic effects limit our ability to ascertain directly from the biomarker records the absolute magnitude that different types of primary productivity have changed at this ocean location over the past 26 kyr

sulphur and oxygen sequestration of n c37 and n c38 unsaturated ketones in an immature kerogen and the release of their carbon skeletons during early stages of thermal maturation sedimentary rock from the gessoso solfifera formation messinian in the vena del gesso basin northern italy containing immature ro 0 25 s rich organic matter was artificially matured by hydrous pyrolysis at temperatures from 160 to 330 c for 72 h to study the diagenetic fate of n c37 and n c38 di and tri unsaturated methyl and ethyl ketones alkenones biosynthesised by several prymnesiophyte algae during early diagenesis the alkenones are incorporated into the kerogen by both sulphur and oxygen cross linking as indicated by chemical degradation experiments with the kerogen of the unheated sample heating at temperatures between 160 and 260 c which still represents early stages of thermal maturation produces large amounts up to 1 mg g toc of s bound o bound and both s and o bound n c37 and n c38 skeletons saturated n c37 and n c38 methyl ethyl and mid chain ketones c37 and c38 mid chain 2 5 di n alkylthiophenes c37 and c38 1 2 di n alkylbenzenes and c37 and c38 n alkanes with increasing thermal maturation three forms of the n c37 and n c38 skeletons are relatively stable saturated hydrocarbons 1 2 di n alkylbenzenes and saturated ketones whereas the s and o bound skeletons are relatively labile these results suggest that in natural situations saturated ketones with an n c37 and n c38 skeleton can be expected as well as the corresponding hydrocarbons

a multiproxy peat record of holocene mangrove palaeoecology from twin cays belize the extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core tcc2 taken from twin cays belize record palaeoecological changes since 8000 cal yr bp the proxies included pollen and the stable isotope c n and o compositions of mangrove leaf fragments rhizophora mangle red mangrove has been dominant at this site on twin cays for over 8000 years variations in 13 c and 15n suggest past changes in stand structure between dwarf transition and tall r mangle through the holocene marked changes in the 18o up to 4 of mangrove leaf fragments throughout tcc2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves reflecting the degree of inundation of the site with seawater resulting from changes in the rate of holocene sea level rise notably a decline in peat accumulation rate at 7200 cal yr bp correlate

biogeochemistry of lipids in surface sediments of the peru upwelling area at 15 s abstract organic carbon lycopane a monoene of 2 6 10 trimethyl 7 3 methyl butyl dodecane c37 alkenones and 20 5 and 22 6 polyunsaturated fatty acid concentrations in two box cores from the peru continental margin area at 15 s in 90 and 268 m water depth have depth profiles that are synchronous and appear to indicate an historical record of fluctuating higher productivity lower productivity enso periods the u37k ratio calculated using c37 2 and c37 3 alkenones in the 268 m water depth core in the center of the upwelling zone varies with depth in the core in a manner consistent with the u37k functioning as an historical recorder of euphotic zone temperature concentrations and cpi for n alkanes c25 c31 are reported for both cores a c27 anthrasteroid has been identified and quantified in the 268 m water depth core

the organic geochemistry of peru margin surface sediments i a comparison of the c37 alkenone and historical el nino records abstract the alkenone u k 37 paleothermometer has potential as a sedimentary marker for el nino southern oscillation enso events in the peru upwelling regime we assessed this potential by comparing the historical enso record with detailed u k 37 profiles for 210 pb dated cores from the peru margin oxygen minimum zone omz sediments with the greatest potential for holding a sedimentary u k 37 record of el nino events are sediments from the center of the omz sectioned at intervals the yearly sedimentation rate the u k 37 signals of individual el nino events were substantially attenuated in the sediments we examined and periods of frequent enso activity e g 1870 1891 were more readily identified than isolated enso events in periods of less frequent enso activity detailed depth profiles of the c 37 alkenones in a core from 253 m o 2 k 37 values for the five 2 mm sections from 0 1 cm suggests that the u k 37 may be unaffected by the alkenone loss correlation between the c 37 alkenone concentration profiles in two cores from 15 s collected nine years apart are consistent with the use of these compounds for molecular stratigraphy

modifications of the c37 alkenone and alkenoate composition in the water column and sediment possible implications for sea surface temperature estimates in paleoceanography 1 the literature pertaining to c37 alkenone and c37 and c38 alkenoate production and diagenesis has been reviewed and evaluated for issues that might jeopardize their usefulness in paleotemperature estimation we also examined the use of the c37 alkenones as paleoproductivity indicators the stability of their 13c isotopic compositions and their incorporation into the nonsolvent extractable organic matter fraction biological transformation of organic matter by bacteria and zooplankton does not appear to cause significant changes to the ratio of c37 2 and c37 3 alkenones but there are major alterations in the relative composition of alkenoates studies of water column processes and postdepositional sedimentary changes indicate overall stability in the c37 2 c37 2 c37 3 ratio leading to effective preservation of the paleotemperature signal this is not the case for alkenoates and there also appear to be some doubts about the dependence between sea surface temperature and the sedimentary abundance of the c37 4 alkenone c37 alkenones may provide useful qualitative estimates of marine paleoproductivity although these compounds are apparently only derived from haptophycea changes in their quantitative composition might reflect changes in nutrient availability that on sedimentary timescales should also be generally significant of other algal species one caveat is that in highly productive upwelling systems productivity may be expressed mostly in diatom growth and thus not measurable by the c37 alkenones no changes in 13c c37 alkenone composition are observed upon zooplankton ingestion although this is expected from a theoretical perspective further studies are encouraged in order to fully assess the stability of the isotopic signal during c37 alkenone diagenesis finally alkenones bound in the nonextractable fraction of sedimentary organics have not been adequately studied and further work is required to clarify any possible correspondence with a temperature signal

late quaternary insolation forcing on total organic carbon and c37 alkenone variations in the arabian sea we here present records of total organic carbon toc and c37 alkenones used as indicators for past primary productivity from the western was and eastern arabian sea eas new data from an open ocean site of the was upwelling area are compared with similar records from ocean drilling program odp site 723 from the continental margin off oman and md 900963 from the eas these records together with other proxies used to reconstruct upwelling intensity indicate periods of high productivity in tune with precessional forcing on the basis of their phase relationship to boreal summer insolation they can be divided into three groups in the was differences between monsoonal proxies 1 and productivity 2 document a combined signal of moderate sw monsoon winds and of strengthened and prolonged ne monsoon winds whereas in the eas phasing indicates maximum productivity 3 at times of stronger ne monsoon winds associated with precession related maxima in ice volume

siwalik mammals of the jammu sub himalaya india an appraisal of their diversity and habitats abstract the red bed sequence of the lower siwaliks around ramnagar and the nagrota formation of the upper siwaliks in the uttarbeni parmandal section are the two highly fossiliferous intervals of the siwaliks of jammu sub himalaya india the lower siwalik mammalian fauna of ramnagar is best represented in its upper 350 m interval small and medium sized forms mostly belonging to browsing species dominate the mammalian assemblage the ramnagar fauna represents the chinji mammalian fauna middle miocene of the potwar plateau pakistan the assemblage indicates a woodland type ecosystem having substantial forest component and subordinately developed grassy subareas the mammalian fauna of the nagrota formation in the uttarbeni parmandal section in contrast exhibits relatively low species diversity but considerable increase in the mean body size and progressive hypsodonty of the cheek teeth in the herbivores this becomes more pronounced above the 2 5 ma old volcanic tuff layers occurring at the middle of the formation broadly a savanna type ecosystem is indicated by the mammalian communities of nagrota formation which appears to have been dominated by grassland communities above the tuff zone the above tuff faunal zone of the nagrota formation can be correlated with the pinjor faunal zone plio pleistocene of the siwalik hills punjab

evidence for a warm last glacial maximum in the nordic seas or an example of shortcomings in uk 37 and uk 37 to estimate low sea surface temperature the occurrence of ice free conditions in the nordic seas during the last glacial maximum has been demonstrated using microfossil and biomarker approaches an accurate picture of the prevailing oceanographic conditions may be more difficult to ascertain thus uncertainties for most proxies increase at the cold extreme of temperature calibrations and glacial sediments contain small amounts of microfossils and biomarkers here we discuss sea surface temperature estimates derived from alkenone indices for the last glacial maximum in the nordic seas that provide a surprising scenario where surface temperatures were warmer than at present we conclude that the uk37 and uk37 estimates may not be interpreted in terms of sea surface temperature as several factors may have conspired to bias the molecular signal however using an alternative index based on the abundance of the c37 4 alkenone we estimate a maximum temperature of 6 c

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

bottom and suspended particle sizes implications for modern sediment transport in quinault submarine canyon abstract electronic particle size analysis of suspended particulate matter and seabed sediments collected over a two year field study of quinault canyon indicates that fine silts 5 9 m modal diameter dominate canyon sedimentation these sediments are markedly finer than the coarse silts 20 40 m modal diameter characteristic of shelf sediments at the canyon head most of the suspensate delivered to the canyon is derived from the intermediate nepheloid layer inl over the slope which in turn originates from the bottom nepheloid layer bnl on the shelf current meter data and particle sizes suggest that sediment accumulating in the upper head of the canyon m is derived directly from the mid shelf silt deposit sediment accumulating in lower portions of the canyon head and in the lower canyon 1000 m depth is apparently resuspended from the outer shelf south of the canyon transport is dominantly across canyon rather than offshore in a north northwesterly direction storms strongly influence sediment transport dramatically increasing suspensate modal sizes in the uppermost portions of the canyon head m depth and over the shelf break storms produce less significant changes in particle size distributions on the open slope m and no apparent changes in the deeper portions of the canyon 1000 m rapid settling of 30 m particles restricts sand and coarse silt accumulation primarily to the southern portion of the upper canyon head

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

exotic conglomerates of the neogene siwalik succession and their implications for the tectonic and topographic evolution of the western himalaya

organic petrology of subbituminous carbonaceous shale samples from chalāw kabul province afghanistan considerations for paleoenvironment and energy resource potential abstract neogene subbituminous carbonaceous shale deposits from chal w afghanistan were investigated through organic petrology techniques and standard coal analyses to determine paleoenvironment and potential for resource utilization the chal w deposit approximately 30 km southeast of kabul currently is exploited for brick making and domestic heating and cooking three multiple bench channel samples of the mined bed at chal w were collected and evaluated the presence of significant huminite ranging from 0 2 to 59 0 vol mineral inclusive basis is suggestive of a terrestrial lignin rich precursor plant material measured reflectance values of 0 38 0 55 indicate subbituminous rank this rank suggests burial depths of approximately 1500 m and maximum temperatures of approximately 50 c structured liptinite macerals generally are absent except for some fluorescing morphologies interpreted to be poorly preserved root cork suberinite sponge spicule bioliths including gemmoscleres and megascleres are common these petrographic observations in addition to high mineral matter content 33 to 95 vol medium to high sulfur content 2 1 11 5 wt dry basis db and the presence of common gastropod shell fragments and an aragonite needle chalk bed are consistent with but not directly indicative of a marginal marine or estuarine mangrove depositional environment however additional data are necessary to confirm this hypothesis and deposition in a freshwater environment cannot be ruled out at this time commercial scale development and utilization of the chal w deposit as a thermal fuel resource may be possible using a fluidized bed combustion system which could accept the low quality mine product currently produced samples examined herein contain high ash yield 45 90 wt db high total moisture content 17 39 wt low calorific value 980 6860 btu lb m mmf and have poor agglomerating properties fsi 0 consistent with fuels utilized in fluidized bed combustors however delineation of the extent of the deposit through field investigation will be necessary to make a quantified resource estimate for mine planning

sedimentation distribution and diagenesis of organic matter in a recent carbonate environment abu dhabi u a e abstract in the modern hypersaline carbonate lagoon and sabkha sedimentary environments of abu dhabi united arab emirates three types of organic matter originate respectively from microbial mat avicennia mangrove and halodule lagoonal seagrass the study of recent sedimentary processes and cross sections through the sabkha sediments lead to the definition of organo sedimentary facies based on geochemical and sedimentological criteria this permits the construction of an organo sedimentary sequence which expresses the holocene sedimentary record involving a transgressive and a regressive sequence the various organic facies occur in both sequences heterogeneity within the individual organic facies reflects several factors including sedimentation dynamics mineral matrix oxidation and reduction and selective organic and mineral diagenesis these parameters are discussed in terms of depositional environment and location within the organo sedimentary sequence changes in distribution quantity and preservation potential of the buried organic matter are discussed in terms of sea level changes and sedimentary accretion rates

atlantic core top calibration of the u37k index as a sea surface palaeotemperature indicator abstract a field calibration of the uk index with sea surface temperature is discussed through analysis of an extensive suite of surface sediments n 109 from the northeastern atlantic 2 s 75 n values of u 37 k are compared with sea surface temperatures for overlying waters measured at different depths and seasons to obtain a correlation suitable for palaeotemperature reconstructions the best fit is obtained using surface 0 m temperatures corresponding to caloric winter and autumn months however the annual average spring and summer surface temperature equations also have high correlation coefficients and are also appropriate for climatic studies the results further validate the general applicability of the u 37 k as a climatic proxy because the calibration equations are valid over a wide range of surface water temperatures 0 28 c for different algal populations and are representative of the average contribution of alkenones to sediments as found in sediment cores

evidence for differential degradation of alkenones under contrasting bottom water oxygen conditions implication for paleotemperature reconstruction abstract the successful reconstruction of sea surface temperatures using alkenone paleothermometry u37k has relied on the premise that there is no significant differential degradation of alkenones with different states of unsaturation during diagenetic processes to test this assumption we conducted a comparative study of contemporary sediments in oxic and anoxic bottom waters from the santa monica basin offshore california long chain alkenones were quantified and sea surface temperature were calculated using the calibrated u37k t relationship of prahl et al 1988 our results show that temperature record from the oxic sediments is higher by as much as 4 c compared to those from time equivalent anoxic sediments as a result of differential degradation of long chain unsaturated alkenones and bioturbation mixing in the oxic sediments the differential degradation of c37 3 vs c37 2 alone could account for up to 2 5 c difference between these two records this finding has significant implication in the interpretation of paleo sea surface temperature data using alkenone paleothermometry

depth and seasonality of alkenone production along the california margin inferred from a core top transect alkenone unsaturation indices uk 37 of marine sediment could prove particularly useful on organic rich continental margins where carbonate dissolution hampers the use of other paleoclimatic proxies mccaffrey et al 1990 kennedy and brassell 1992 forty core top samples of recent sediment from a latitudinal transect 23 40 n along the california margin yield uk 37 values that correlate linearly with modern mean annual sea surface temperatures ssts in the range of 12 23 c reproducibility of the unsaturation value in closely spaced cores is near analytical error uk 37 data define a relationship to temperature nearly identical to the prahl et al 1988 laboratory cultures of emiliania huxleyi the close agreement is particularly significant in light of the nannofossil composition of the sediments where the abundance of the coccolith taxon gephyrocapsa oceanica known to synthesize alkenones equals or exceeds that of e huxleyi comparison with seasonal temperature variations at different depths indicates that little if any alkenone production occurs at depths 30 m along the continental margin water depths 2 km sediments in more pelagic locations exhibit small but consistent biases toward winter and or subsurface production similar to previously reported sediment trap and core top data from the oregon margin prahl et al 1993 doose et al 1997

late cretaceous early tertiary convergence between the indian and arabian plates recorded in ophiolites and related sediments abstract remnants of ocean floor forming the eastern ophiolite belt in oman and the western ophiolite belt in pakistan have a common plate tectonic history culminating in emplacement at the cretaceous tertiary boundary fragments of ocean floor in these two belts have ages between 150 and 65 ma and recorded tectonic events in the early indian ocean at 150 ma 130 120 ma 110 100 ma and 70 65 ma new radiometric and chronostratigraphic ages and paleomagnetic and sedimentary information are used to relocate these ophiolites in the frame of the evolving indian ocean which was characterised by the stepwise breakup of gondwana at 158 ma east and west gondwana 130 ma southern atlantic breakup of east gondwana 95 84 ma madagascar and india seychelles 65 ma india and seychelles and finally at 40 ma rifting between africa and arabia the 150 ma old oceanic rocks of masirah island in oman originally formed the extension of the basins now preserved along the eastern edge of the afro arabian plate masirah drifted together with india seychelles when a new ridge formed at approximately 130 ma separating microplates e g kabul block from the northern edge of greater india parts of this new ocean were later emplaced to form the western ophiolite belt in pakistan consumption of oceanic crust and emplacement of ophiolites during the closure of the neotethys occurred not only north of india seychelles but also along two or three subduction zones between the afro arabian plate and india seychelles documented by the formation of metamorphic soles beneath ophiolites relics of ocean floor formed approximately 65 70 ma ago now form the upper units in the western ophiolite belt of pakistan where they overlie an accretionary prism of pillow lavas of dominantly aptian albian age and sedimentary rocks the breakup of india and the seychelles at 65 ma was associated with the eruption of flood basalts deccan and seychelles and enhanced counter clockwise movement of india this breakup possibly caused the late jurassic early cretaceous fragments of ocean floor e g masirah to be thrust onto the eastern edge of oman the ophiolites which were emplaced onto the western edge of india drifted as part of this plate farther north where collision with eurasia and the accreted microplates occurred in the eocene 55 ma

climate induced variations in productivity and planktonic ecosystem structure from the younger dryas to holocene in the cariaco basin venezuela a high resolution molecular organic geochemical study of sediments in the anoxic cariaco basin indicates significant changes in primary productivity and planktonic community structure associated with the transition from the younger dryas to the holocene variations in climate conditions over the past 12 14c kyr have induced large scale changes in upwelling intensity which directly affected levels of primary productivity as reflected in accumulation rates of bulk productivity proxies concentrations and accumulation rates of sterol and alkenone biomarkers have been used to identify how productivity changes affected the structure of the planktonic ecosystem a shift in the dominant primary producer from diatoms younger dryas to coccolithophores holocene is identified if productivity and ecosystem variations like those identified in the tropical upwelling zone of the cariaco basin region occur throughout the tropical oceans they have the potential to affect global climate through perturbations in the biogeochemical cycle of carbon

middle permian environmental changes and shale oil potential evidenced by high resolution organic petrology geochemistry and mineral composition of the sediments in the santanghu basin northwest china abstract shales in the middle permian lucaogou formation have been considered as one of the most important unconventional reservoirs in nw china due to their excellent shale oil and tight oil potential based on the data of previous organic geochemical studies the overall evolution of the ecosystem in the lake water conditions and organic matter sources have been outlined here we present the results of the mineralogical and organic petrological examinations and the rock eval pyrolysis on samples of a fine grained mixed carbonate clastic sedimentary succession from the santanghu basin providing new detailed insights into paleoenvironmental evolution and lake level changes in addition shale oil potential was further evaluated on this oil prone shale analytical results from a total of 196 shale samples from the second member of the lucaogou formation collected from one newly drilled core indicate algal microbial sources of organic matter classified by rock eval pyrolysis as type i kerogen samples characterized by lower hydrogen index hi values type ii kerogen contain increased contributions of terrigenous organic matter evidenced by enhanced inertinite and vitrinite contents vertical variations in mineralogical and bulk geochemical composition reflect an evolution from a saline anoxic to a deep freshwater lake two environmental changes subdivided the sequence into three units the boundary between the lower unit i and the middle unit ii is characterized by the drastic decrease of smectite and k feldspar contents and a sharp increase in total organic carbon toc content the upper unit iii is distinguished by high toc s ratios based on variations in petrography and carbon isotopes of hopanes the middle unit ii can be further subdivided into two parts reflecting changes in water level of the lake all the periods of high water level are characterized by higher lamalginite contents 40 vol and higher hi values than those obtained from sediments deposited during periods of shallower water levels deposition in a shallow lake is evidenced by increased dolomite and decreased lamaginite contents lake level fluctuations indicated by mineralogical and geochemical parameters are associated with changes in organic matter sources leading to the great variability in mineral content organic petrography and hydrocarbon generation potential high toc and brittle minerals contents micro nanopores system and large thickness of the shale show that the lucaogou formation holds a significant shale oil potential in areas where oil window maturity is reached

the relationship between sedimentary organic carbon isotopic composition and organic biomarker compound concentration abstract a study of organic biomarker compounds which could serve as tracers of terrigenous and marine sedimentary organic matter sources was performed on samples from a 208 7 m hydraulic piston core hole dsdp hole 619 from the hemipelagic pigmy basin in the northern gulf of mexico organic carbon normalized concentrations of total long chain c37 c39 alkenones and some individual c27 c29 desmethyl sterols were determined to be useful proportional indicators tracers of preserved marine and terrigenous organic carbon respectively the alkenones whose only known source is marine phytoplankton of the class prymnesiophyceae generally occurred in higher concentrations in interglacial isotope stages 1 and 5a b than in the intervening glacial stages sterols c27 c29 apparently of a dominantly terrigenous origin occurred in lower concentrations during interglacial stages than in glacial stages tracers of both terrigenous and marine organic matter appear to be affected by the differential diagenetic alteration of the biomarker corg ratios as indicated by a simple first order kinetic model the lack of any desmethylor 4a methylsterol which is linearly related to the proportion of marine sedimentary organic matter as scaled by 13corg indicates that either 1 1 sedimentary diagenesis has obscured the biomarker corg vs 13corg record 2 2 phytoplanktonic assemblage changes caused variations in the biomarker corg ratio of the primary input preferential preservation of terrigenous sterols may result in a biased sedimentary record of sterol input which could be misinterpreted as indicating solely terrigenous sterol sources a simple model which characterizes the effects of sedimentary diagenesis on the relationship between corg normalized biomarker ratios and 13corg demonstrates the potential problems of long term differential diagenetic skewing on those tracer records

erroneous coal maturity assessment caused by low temperature oxidation previous work carried out on different outcrop coals from the french massif central revealed abnormally high tmax values which initially were attributed to high temperature oxidising fluids this increase in tmax which was exclusively observed for medium to low volatile bituminous coals rr 1 5 was accompanied by a very clear exponential like decrease of the hydrogen index hi together with an increase in the oxygen index oi with the aim of checking the possibility that this rise in tmax could simply be caused by weathering a few mature coal samples rr 1 4 were experimentally oxidised at rather low temperatures 110 125 and 150 c and for durations of up to 6 5 month then the oxidation residues were subjected to rock eval 6 pyrolysis and to vitrinite reflectance measurements these experiments effectively reproduce the geochemical changes displayed by the naturally altered coals thus supporting the hypothesis that the previously studied natural alteration process could have been ultimately caused by weathering the observed artificial oxidation path could be divided into two stages i a strong decrease in hi and an increase in oi and ii a constant hi value and a slow rise in oi the increase in tmax seems related to the transition between the first and the second stages this behaviour of hi and oi during artificial oxidation suggests that these two rock eval derived indices can be practically used to detect a moderate and even a low oxidation degree finally if one ignores the constancy of the vitrinite reflectance values all along the oxidation path the decrease of hi and the concomitant increase of tmax mimic a thermal evolution pathway

palaeoclimatic signals recognized by chemometric treatment of molecular stratigraphic data abstract the high resolution stratigraphy of various marker compounds has been studied using gc hplc and gc ms in a 13 m gravity core recovered from the kane gap region eastern equatorial atlantic which provides a record of the glacial interglacial episodes over the last million years downhole variations in many presumed source specific components are observed e g in n alkanes from terrigenous land plants and dinosterol from dinoflagellates which may be due to perturbations or cyclicities resulting from climatic change fluctuations in the unsaturation of alkenones attributable to variations in water temperatures show correlations with the glacial interglacial cycles recorded in the 18 o values for planktonic foraminifera thereby providing a potential organic geochemical measure of past climates these molecular abundance data can be linked to the palaeotemperature record following computer treatments using principal component and spectral analyses molecular stratigraphy shows promise as a new chemostratigraphical tool where other means of stratigraphy fail for example through calcium carbonate dissolution

mesozoic ophiolites sutures and arge scale tectonic movements in afghanistan abstract the tectonic history of afghanistan appears to be the result of successive accretion of fragments of gondwana to the active margin of laurasia since the end of the paleozoic the margin in afghanistan lies along the present herat and panjshir faults south of hindu kush swings around the central pamirs and can presumably be traced along the present western altyn tagh and kunlun faults in tibet north of this boundary paleozoic rocks have been deformed in the upper paleozoic whereas south of it there is no trace of the hercynian orogeny the first collision of gondwanian fragments with laurasia probably occurred in the early mesozoic along the hindu kush and kunlun to the south ophiolites along the panjao and pangong nu chiang sutures respectively in central afghanistan and central tibet testify for another suturing event in the upper jurassic or lower cretaceous the indus tsangpo suture between india and tibet corresponds in eastern afghanistan to two ophiolite subbelts near kabul and khost both ophiolite complexes have been emplaced between maestrichtian and lower eocene by choking of two northward dipping subduction zones after complete contact between the indian and asian continents was achieved presumably in the end of eocene the penetration of india into asia caused large scale intra continental shortening a large part of the shortening was accommodated by strike slip faulting along mesozoic and more ancient sutures central afghanistan in particular was extruded to the west along the herat suture by the protrusion of the pamir wedge it subsequently collided with the lut block

diagenetic trends in the siliceous facies of the monterey shale in the santa maria region california x ray diffraction and oxygen isotopic analyses of outcrop and subsurface samples of siliceous rocks were used to reconstruct thermal and diagenetic histories of the miocene monterey shale near santa maria california within many stratigraphic sections soft porous diatomaceous rocks change gradationally to underlying hard and brittle chert porcellanite and siliceous shale the accompanying silica mineral zones are in descending stratigraphic order 1 biogenic silica opal a 2 cristobalitic silica opal ct and 3 microcrystalline quartz boundaries between silica mineral zones and stratigraphic horizons are often discordant within the opal ct zone the d 101 spacing of opal ct decreases in a smooth non linear fashion from about 4 10 a to 4 04 a in the santa maria valley and bradley oil field areas the thicknesses of the opal ct zones are greater and the present thermal gradients less than in the adjacent orcutt oil field thin opal ct zones at shallow maximum burial depths apparently correlate with higher thermal gradients using present thermal gradients and reconstructed maximum burial depths from well data in the santa maria region the ranges in temperatures for the top and base of the opal ct zone are 38 54 c and 55 110 c respectively the temperature difference between these two boundaries ranges from 17 to 60 c in comparison temperature ranges for these two boundaries computed from oxygen isotopic compositions of opal ct and quartz extrapolated experimental quartz water fractionations and assuming o18 0 o for the isotopic composition of the equilibrating fluid are 18 56 c and 31 80 c for the top and base of the opal ct zone respectively the temperature difference between these boundaries is 11 36 c using this method thermal gradients and sedimentation rates strongly influence rates of silica transformations reconstructed thermal and diagenetic histories of siliceous rocks of the monterey shale at four well sites in the santa maria region demonstrate that most silica conversions probably occurred during the last 3 4 myr in response to accelerated rates of sedimentation and therefore burial heating during the pliocene

alkenones and alkenes in surface waters and sediments of the southern ocean implications for paleotemperature estimation in polar regions abstract the concentration of c37 c39 long chain alkenones and alkenes were determined in surface water and surface sediment samples from the subpolar waters of the southern ocean distributions of these compounds were similar in both sample sets indicating little differential degradation between or within compound classes the relative amounts of the tri to tetra unsaturated c37 alkenones increased with increasing temperature for temperatures below 6 c similar to the di and tri unsaturated c37 alkenones the c37 di tri and tetra unsaturated methyl alkenones are used in paleotemperature calculations via the u37k and the u37k ratios in these datasets the relative abundances of the c37 2 and the c37 3 alkenones as a proportion of the total c37 alkenones were opposite and strongly related to temperature the latter with more scatter but the abundance of the c37 4 alkenone showed no relationship with temperature the original definition of u37k includes the abundance of 37 4 in both the numerator and denominator and thus it is perhaps not surprising that there is considerable scatter in the values obtained for u37k at low temperatures of the two we suggest that u37k is the better parameter for use in paleotemperature estimations even in cold locations u37k values in the sediments fall on virtually the same regression line obtained for the water column samples of sikes and volkman 1993 indicating that their calibration is suitable for use in southern ocean sediments the comparison of water column data with sedimentary temperature estimates suggests that the alkenone distributions are dominated by contributions from the summer when the biomass of emiliania huxleyi and presumably flux to the sediment is expected to be high

combined coccolith foraminiferal and biomarker reconstruction of paleoceanographic conditions over the past 120 kyr in the northern north atlantic 59 n 23 w we present data for north atlantic core biogeochemical ocean flux study bofs 16k 59 n 23 w water depth 2370 m including coccolith flora 18o planktonic foraminiferal sea surface temperatures ssts by fa20 and simmax methods and alkenone based u37k and u37k ssts a good correlation exists between the abundances of cold water coccolith species and foraminifera and a broad correlation exists between coccolith and alkenone abundances except in the holocene reworked cretaceous coccoliths at the last glacial maximum are coincident with warm deviations of the u37k signal assessment of various calibrations of u37k and u37k with paleotemperature shows the inappropriateness of a global correlation we have produced a north atlantic u37k calibration on the basis of north atlantic data alone u37k 0 026t 0 186 which produces sst data for summer season at 0 m water depth comparable to the warm season foraminiferal ssts except during the intervals 26 36 58 65 and 100 120 ka when the alkenones indicate somewhat cooler surface waters

petrographic geochemical and mycological aspects of miocene coals from the novaky and handlova mining districts slovakia abstract fungi have once again become a topic of interest to coal scientists in their roles as agents of maceral formation recent works have demonstrated that fungi occur in association with woody remains resins and cuticles in coalified materials of a variety of ages in addition to coal balls and compression impression fossils where they are already well known these forms however have only been viewed as cross sections along a polished plane assigning the fungi to family much less determining which fungi they represent is very difficult in this orientation fungal identifications are necessary to the continuance of this research into the origin of coal macerals because of the need to know if macrinite begins to form prior to incorporation into the peat which could be demonstrated by its association with symbiotic and parasitic rather than saprophytic fungi this study examines the fungal remains recovered from eight coal samples from miocene age coals in the novaky and handlova mining districts of slovakia with the aim of making this distinction these samples were collected in slovakia as part of the us geological survey s world coal quality inventory program and provided to the authors the samples were processed using the o keefe technique for subbituminous coals and mounted for observation in transmitted light forms were identified using published works and consultation with a modern mycologist forms recovered through palynologic processing were compared to and correlated with forms seen in cross section under reflected light

influence of rock composition on kinetics of silica phase changes in the monterey formation santa barbara area california the diatomaceous deposits of the monterey formation along the santa barbara coast were subjected to temperatures and burial depths that increased westward after deposition as a result the silica phase in originally similar laterally equivalent strata generally changed westward from biogenous opal a to diagenetic opal ct to diagenetic quartz in individual beds at the same stratigraphic level however silica phases changed at various temperatures producing a transformation or kinetic sequence related to variations in the ratio of silica to detrital minerals compared to silica in rocks with minor detrital minerals in rocks with progressively more abundant detrital minerals 1 opal ct formed progressively later 2 the initial d spacing of opal ct was progressively smaller and 3 quartz formed progressively earlier comparison of associated calcareous dolomitic and carbonate free rocks with equal silica detrital ratios shows that carbonates did not significantly affect rates of silica diagenesis in the vast majority of rocks in carbonate bearing rocks with silica detrital ratios 8 however some 2 to 10 quartz formed early in diagenesis probably prior to opal ct formation in addition atypical quartz cherts formed locally in carbonate bearing strata by pore filling and replacement early in diagenesis possibly before widespread opal ct formation

petrography and geochemistry of selected lignite beds in the gibbons creek mine manning formation jackson group paleocene of east central texas this study examined the petrographic and geochemical characteristics of two lignite beds 3500 and 4500 beds manning formation jackson group eocene that are mined at the gibbons creek mine in east central texas the purpose of the study was to identify the relations among sample ash yield coal petrography and trace element concentrations in lignite and adjoining rock layers of the gibbons creek mine particular interest was given to the distribution of 12 environmentally sensitive trace elements as be cd cr co hg mn ni pb sb se and u that have been identified as potentially hazardous air pollutants haps in the united states clean air act amendments of 1990 eleven lignite floor and rock parting samples were collected from incremental channel samples of the 3500 and 4500 beds that were exposed in a highwall of pit a3 at the gibbons creek mine short proximate and ultimate and forms of sulfur analyses were performed on all lignite samples and lignite and rock samples were analyzed for 60 major minor and trace elements representative splits of all lignite samples were ground and cast into pellets and polished for petrographic analyses in blue light fluorescence and reflected white light to determine liptinite inertinite and huminite maceral group percentages the following observations summarize our results and conclusions about the geochemistry petrography and sedimentology of the 3500 and 4500 beds of the gibbons creek lignite deposit 1 weighted average dry db ash yield for the two beds is 29 7 average total sulfur content is 2 6 and average calorific value is 7832 btu 18 22 mj kg ash yields are greatest in the lower bench 59 33 db of the 3500 bed and in the upper bench of the 4500 bed 74 61 db 2 for lignite samples on a whole coal basis the distributions of two of the haps pb and sb are positively related to ash yield probably indicating an inorganic affinity for these elements by using cluster analysis we found that be and cd were poorly associated with ash yield indicating a possible organic affinity and that ni se hg u and pb cluster with most of the rare earth elements 3 the dominance of the crypto eugelinite maceral subgroup over the crypto humotelinite subgroup suggests that all gibbons creek lignites were subjected to peat forming conditions either biogenic or chemical conducive to the degradation of wood cellular material into matrix gels or that original plant material was not very woody and was prone to formation of matrix gels the latter idea is supported by pollen studies of gibbons creek lignite beds results indicate that the peat was derived in part from marsh plants low in wood tissue 4 the occurrence of siliceous sponge spicules in the lower benches of the 3500 bed suggests the original peat in this part of the bed was deposited in standing fresh water 5 the petrographic data indicate that the upper sample interval of the 3500 bed contains more inertinite 3 than the other samples studied increases in inertinite content in the upper part of the 3500 bed may have been associated with alteration of the peat by acids derived from the volcanic ash or could have been caused by fire oxidation and drying or biologic alteration of the peat in the paleo mire

interhemispheric appraisal of the value of alkenone indices as temperature and salinity proxies in high latitude locations alkenone sediment data from the nordic seas and north atlantic are compared to those from sikes et al 1997 for the southern ocean to evaluate further uk37 and uk37 as proxies to estimate cold temperatures 10 c and the effect of salinity and temperature in the relative abundance of 37 4 to the total abundance of c37 alkenones 37 4 uk37 and uk37 are found to be equally viable as proxies but there are significant regional differences in their cold temperature dependence the measurement of 37 4 in cores from the north atlantic region can be used to identify situations when uk37 is not a reliable paleothermometer variations in salinity are probably responsible for changes in the sedimentary record of 37 4 and a preliminary calibration has been obtained for 37 4 f salinity this new relationship should be further confirmed through field or laboratory experiments but it paves the way to derive a molecular proxy to reconstruct paleosalinity in surface waters