eocene cooling linked to early flow across the tasmanian gateway the warmest global temperatures of the past 85 million years occurred during a prolonged greenhouse episode known as the early eocene climatic optimum 52 50 ma the early eocene climatic optimum terminated with a long term cooling trend that culminated in continental scale glaciation of antarctica from 34 ma onward whereas early studies attributed the eocene transition from greenhouse to icehouse climates to the tectonic opening of southern ocean gateways more recent investigations invoked a dominant role of declining atmospheric greenhouse gas concentrations e g co2 however the scarcity of field data has prevented empirical evaluation of these hypotheses we present marine microfossil and organic geochemical records spanning the early to middle eocene transition from the wilkes land margin east antarctica dinoflagellate biogeography and sea surface temperature paleothermometry reveal that the earliest throughflow of a westbound antarctic counter current began 49 50 ma through a southern opening of the tasmanian gateway this early opening occurs in conjunction with the simultaneous onset of regional surface water and continental cooling 2 4 c evidenced by biomarker and pollen based paleothermometry we interpret that the westbound flowing current flow across the tasmanian gateway resulted in cooling of antarctic surface waters and coasts which was conveyed to global intermediate waters through invigorated deep convection in southern high latitudes although atmospheric co2 forcing alone would provide a more uniform middle eocene cooling the opening of the tasmanian gateway better explains southern ocean surface water and global deep ocean cooling in the apparent absence of sub equatorial cooling

racemization of amino acids in fossil bones and teeth from the olduvai gorge region tanzania east africa abstract investigation of amino acid racemization in fossil bones and teeth from the olduvai gorge region tanzania indicates that aspartic acid racemization can be used to date samples which are less than 80 000 100 000 years old in this area in older samples significant secondary aspartic acid is apparently present and thus these samples have lower than expectedd l aspartic acid ratios isoleucine in older samples however is apparently syngenetic with the samples so the epimerization of isoleucine to alloisoleucine can be used with certain limitations to date fossil bones and teeth from the older stratigraphic sections in the olduvai region

fluid inclusions and h o s pb isotope systematics of the baishan porphyry mo deposit in eastern tianshan china abstract the baishan porphyry mo deposit formed in the middle triassic in eastern tianshan xinjiang northwestern china mo mineralization is associated with the baishan monzogranite and granite porphyry stocks mainly presenting as various types of hydrothermal veinlets in alerted wall rocks with potassic phyllic propylitic and fluorite alteration the ore forming process can be divided into four stages stage i k feldspar quartz pyrite veinlets stage ii quartz molybdenite pyrite veinlets stage iii quartz polymetallic sulfide veinlets and stage iv barren quartz calcite veins four types of fluid inclusions fis can be distinguished in the baishan deposit namely liquid rich two phase l type vapor rich two phase v type solid bearing multi phase s type and mono phase vapor m type inclusions but only the stage i quartz contains all types of fis the stages ii and iii quartz have three types of fis with exception of m type in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 271 468 c 239 349 c 201 331 c and 134 201 c with salinities of 2 2 11 6 wt nacl equiv 1 1 10 2 wt nacl equiv 0 5 8 9 wt nacl equiv and 0 2 5 7 wt nacl equiv respectively the ore forming fluids of the baishan deposit are characterized by high temperature moderate salinity and relatively reduced condition belonging to a h 2 o nacl ch 4 co 2 system hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials came predominantly from a deep seated magma source from the lower continental crust the mo mineralization in the baishan deposit is estimated to have occurred at a depth of no less than 4 7 km and the decrease in temperature and remarkable transition of the redox condition from alkalinity to acidity of ore forming fluids were critical for the formation of the baishan mo deposit

geochronology and geochemistry of late paleozoic magmatic rocks in the lamasu dabate area northwestern tianshan west china evidence for a tectonic transition from arc to post collisional setting abstract voluminous late paleozoic igneous rocks and associated cu au mo deposits occur in the northwestern tianshan district xinjiang west china however the tectonic setting and petrogenesis of these rocks remain controversial this paper reports zircon u pb and hf cuu isotopic data major and trace elements and sr nd pb isotopic data for the intrusive rocks and minor dacites in the lamasu dabate area of northwestern tianshan adjacent to the cu au mo deposits la icpms u pb zircon analyses suggest that the lamasu porphyries were formed at 366 3 ma and contain 907 738 ma inherited zircons the dabate dacites were formed at 316 4 ma and granite porphyries were formed at 289 3 ma with 319 ma inherited zircons the lamasu porphyries consist of plagioclase granite and granodiorite and are geochemically similar to adakites e g having high al2o3 14 54 19 75 wt and sr 308 641 ppm and low y 7 84 16 9 ppm contents with fractionated rare earth element ree patterns and slightly positive sr anomalies however they have variable initial ratios of 87sr 86sr 0 7072 0 7076 and 206pb 204pb 18 139 18 450 and variable end t 5 6 to 0 8 and positive ehf t 1 4 to 10 6 values they also have variable mg 100 mg2 mg2 fe2 41 73 and low th 3 13 8 09 and th ce 0 14 0 28 values we suggest that the lamasu adakitic magmas were generated through partial melting of southward subducted junggar oceanic crust with subsequent melt mantle interaction and assimilation of basement rocks the dabate dacites show typical arc like geochemical characteristics e g enrichment of large ion lithophile elements lile and strong negative anomalies of ta nb p and ti with variable end t 0 1 to 3 3 they were probably generated by melting of juvenile basaltic lower crust as a result of magma underplating the dabate granite porphyries are geochemically similar to a2 type granites e g high sio2 75 6 77 6 wt and alkalis na2o k2o 8 27 8 70 wt low cao 0 28 0 34 wt and mg 2 10 and obvious negative eu ba and sr anomalies they have variable values of end t 1 7 to 0 and 206pb 204pbi 18 567 18 721 and zircon ehf t 0 5 to 11 1 the dabate a type granite porphyries contain late carboniferous residual zircon cores suggesting that their source rock possibly contained carboniferous arc igneous rocks taking into account all available data from late paleozoic magmatic rocks and cu mo au mineralization in the northern tianshan district we suggest that the dabate lamasu area was a continental arc during the late devonian carboniferous but had entered a post collisional stage by the early permian 290 ma

palaeoenvironmental assessment of westphalian fluvio lacustrine deposits of lorraine france using a combination of organic geochemistry and sedimentology abstract the quality and the quantity of organic carbon preserved in modern and ancient terrestrial sediments is the result of a complex interactions of sedimentological factors such as in situ productivity allochtonous supply of organic matter oxidation processes biodegradation and sediment accumulation rates the study aims at utilizing multidisciplinary information in order to characterize the palaeoenvironment in westphalian fluvio lacustrine deposits of the lorraine coal basin ne france in this basin the lack of outcrops is the major difficulty to compensate for this problem sedimentology and molecular geochemistry are combined in order to significantly improve the palaeoenvironmental assessment of the area geochemical analyses and sedimentology have been carried out on several core samples of the saulcy drill hole to evaluate local palaeoenvironmental variability the lithofacies associations in the upper carboniferous of the lorraine basin suggest an alluvial plain environment without marine incursions sedimentological interpretations of the core as well as comparison with sedimentological models suggests the recognition of different depositional environments from braided and or meandering rivers to swamp and lakes the organic geochemistry is focussed on the recognition of aliphatic hydrocarbons and especially on molecular biomarkers which provide valuable information about the original organic matter and the transformations that took place during sedimentation and diagenesis in the lorraine basin the botanical variability is high and clearly related to the position of the vegetation communities in the fluvial system the biomarkers e g diterpanes steranes show variations which can be related to the diversity of this ecosystem in this study a reinterpretation of the environmental zonation in the sterane ternary diagram adapted to a fluvio lacustrine sedimentology is proposed the correlation between sedimentological and geochemical interpretation permits characterization of various depositional environments a palaeoenvironment model relating sediment deposition conditions and organic matter characteristics is proposed

methane origin and oxygen fugacity evolution of the baogutu reduced porphyry cu deposit in the west junggar terrain china most porphyry copper deposits worldwide contain magnetite hematite and anhydrite in equilibrium with hypogene copper iron sulfides chalcopyrite bornite and have fluid inclusions with co2 ch4 that are indicative of high fo2 in contrast the baogutu porphyry cu deposit in the west junggar terrain xinjiang china lacks hematite and anhydrite contains abundant pyrrhotite and ilmenite in equilibrium with copper iron sulfides chalcopyrite and has fluid inclusions with ch4 co2 that are indicative of low fo2 the mineralized intrusive phases at baogutu include the main stage diorite stock and minor late stage diorite porphyry dikes the main stage stock underwent fractional crystallization and country rock assimilation contamination and consists of dominant diorite and minor gabbro and tonalite porphyry the country rocks contain organic carbons 0 21 0 79 wt the 13cvpdb values of the whole rocks 23 1 to 25 8 in the wall rocks suggest a sedimentary organic carbon source the 13cvpdb values of ch4 28 2 to 36 0 and co2 6 8 to 20 0 in fluid inclusions require an organic source of external carbon and equilibration of their 13cco2 ch4 values 8 2 25 0 at elevated temperatures 294 830 c suggesting a significant contribution of thermogenic ch4 mineral composition data on the main stage intrusions such as clinopyroxene hornblende biotite magnetite ilmenite sphene apatite and pyrrhotite suggest that the primary magma at baogutu was oxidized and became reduced after emplacement by contamination with country rocks mineral compositions and fluid inclusion gas compositions suggest that the redox state of the system evolved from logfo2 fmq 1 in the magma stage to logfo2 fmq in the hydrothermal stage though oxidized magma was emplaced initially assimilation contamination of carbonaceous country rocks decreased its fo2 such that exsolved fluids contained abundant ch4 and deposited a reduced assemblage of minerals

vascular plant biomarker distributions and stable carbon isotopic signatures from the middle and upper jurassic callovian kimmeridgian strata of staffin bay isle of skye northwest scotland the molecular and stable carbon isotopic composition of higher plant biomarkers was investigated in middle to upper jurassic strata of the isle of skye northwest scotland aromatic hydrocarbons diagnostic of vascular plants were detected in each of nineteen sedimentary rock samples from the early callovian to early kimmeridgian interval a succession rich in fossil fauna including ammonites that define its constituent chronozones the higher plant parameter hpp and higher plant fingerprint hpf calculated from the relative abundance of retene cadalene and 6 isopropyl 1 isohexyl 2 methylnaphthalene ip ihmn exhibit several large fluctuations throughout the skye succession studied these molecular profiles contrast with both 1 the more uniform profiles previously observed in jurassic successions putatively of the same age from other palaeogeographical settings including the carnarvon basin western australia and 2 the steady rise in global sea level during this interval this suggests that the hpf profiles of jurassic marine successions may not be reliable indicators of global climate change our results indicate that other factors such as local tectonism resulting in changes to the relief and landscape of the hinterland likely influenced the palaeoflora and the mode of transport of its detritus into adjacent marine depocentres however the skye succession showed similar 13c profiles of total organic carbon toc comprising mainly fossil wood the vascular plant biomarker retene and a predominant phytoplanktonic biomarker phytane the apparent isotopic relationship between terrigenous and marine derived biomarkers supports a strong coupling of the atmosphere and ocean the maximum isotopic excursion occurs in the cardioceras cordatum ammonite biozone of the early to middle oxfordian which may be indicative of changes in atmospheric and oceanic levels of co2

epithermal deposits in north xinjiang nw china the north xinjiang region nw china is an important part of the central asia orogenic belt situated at the junction of siberia tarim and kazakhstan plates it is an area characterized by multiple stages of phanerozoic continental growth during which several porphyry and epithermal systems were formed the relationship of these mineral systems to the geodynamic evolution of the region has not yet been well understood in this paper we list the main geological characteristics of 21 significant epithermal precious and base metal deposits in north xinjiang and classify them into high sulfidation and low sulfidation styles with the latter being predominant we have selected seven epithermal deposits representing different styles formed under different tectonic regimes and discuss their geology and geochemistry in some detail the deposit scale geology and geochemistry of epithermal systems in north xinjiang are essentially similar to those in other parts of the world all epithermal deposits in north xinjiang are hosted in volcanic rocks with ages ranging from devonian to triassic with the early carboniferous volcanic sequences being the most important followed by the permian and triassic the devonian early carboniferous host rocks belong to the calc alkaline series that developed in pre collisional arc back arc basin systems whereas the permian triassic host volcanic rocks of shoshonite series formed in post subduction regimes available isotopic ages of these epithermal systems cluster in two periods early carboniferous 320 ma and late carboniferous triassic 320 220 ma reflecting two metallogenic episodes that occurred during subduction related accretion and post subduction collision regimes respectively accordingly three groups of epithermal deposits in north xinjiang can be recognized as 1 pre collisional deposits without or with negligible collisional related modification 2 deposits formed in collision regime and 3 ore systems strongly overprinted by fluid flow in post subduction collision regime

sesquiterpanes diterpanes and other higher terpanes in oils from the taranaki basin of new zealand abstract the bi tri and tetracyclic terpenoids in crude oils from the taranaki basin of new zealand have been studied the distribution of c14 c15 and c16 bicyclanes was essentially invariant amongst the various fields a suggestion is made that the proportion of rearranged to total drimanes may be related to maturity and the ratio of homodrimane to drimane may be related to depositional environment mass spectra are reported for a number of unidentified sesquiterpanes including possibly norbisabolane and bisabolane the distribution of bi tri and tetracyclic diterpanes was very similar to that of crude oils from the gippsland basin of south east australia the occurrence of rimuane was confirmed 8 h labdane was identified and 4 h 18 norisopimarane was tentatively identified isopimarane dominated the diterpane distribution of oils from the maui field in the south west of the basin and its abundance gradually diminished in a north westerly direction until it became a minor component of oil from the new plymouth field this trend coincided with an increase in the complexity of the triterpane distribution and with the oleanane content of the oils these northwards trends also followed the evolution of coal deposits in the region the diterpanes in these oils had the same structure as those which occur in extant trees of the araucariaceae and podocarpaceae which flourish in new zealand today and did so even more extensively in the past coal measures formed from forests of such trees are probably the source of the diterpanes a situation analogous to that in the gippsland basin of south eastern australia tricyclanes of the cheilanthane series were not detected in any of the taranaki oils lending support to the view that these tricyclanes occur most abundantly in oils derived from marine sources c24 tetracyclanes secotriterpanes occurred abundantly in all the oils as they do in terrigenous oils from other parts of the world

paleoclimatic control of biogeographic and sedimentary events in tethyan and peri tethyan areas during the oxfordian late jurassic abstract the paleobiogeographical distribution of oxfordian ammonites and coral reefs in northern and central europe the mediterranean area north and east africa and the middle east and central asia is compared with the distribution in time and space of the most important lithofacies interest in the oxfordian is focused on changes in facies and in biogeographical patterns that can be interpreted as the results of climatic events paleotemperature trends inferred from oxygen isotopes and paleoclimatic simulations are tested against fossil and facies data a late callovian early oxfordian crisis in carbonate production is indicated by the widespread absence of lower oxfordian reefal formations there is a gap hiatus in deposition on epicontinental platforms with middle oxfordian deposits resting paraconformably on upper callovian while shales accumulated in adjacent intracratonic basins simultaneously in mediterranean tethys radiolarites accumulated in deep troughs while rosso ammonitico facies formed on pelagic swells however deposition on swells was also discontinuous with numerous gaps hiatuses and sequences that are much reduced in thickness middle callovian deposits are generally overlain by middle oxfordian limestones the dearth of carbonates is consistent with a cooling event lasting about 1 my by the middle oxfordian a warming leading to greenhouse type conditions is suggested on the basis of both biogeographical mostly coral reef distribution and geochemical data carbonates spread onto an extensive european platform while radiolarites reached a maximum development in the mediterranean tethys two distinct latitudinal belts with seemingly different accumulation regimes are therefore inferred similar latitudinal belts were also present in the late oxfordian when carbonates were widespread the distribution of reefal facies in the late oxfordian early kimmeridgian fits relatively well with gcms simulations that imply low rainfall in the tethyan mediterranean area and slightly higher precipitation in central and northern europe local salinity variations reflecting more arid or humid conditions may bias the paleotemperature signal inferred from 18o values biogeographical and facies distributions combined with 18o values unravel the ambiguity and support a late callovian early oxfordian cooling followed by warming in the later oxfordian

climatic fluctuations and seasonality during the late jurassic oxfordian early kimmeridgian inferred from δ18o of paris basin oyster shells abstract oxygen isotope data from biostratigraphically well dated oyster shells from the late jurassic of the eastern paris basin are used to reconstruct the thermal evolution of western tethyan surface waters during the early oxfordian early kimmeridgian interval seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy isotope analyses were performed on non luminescent parts of shells n 264 intra shell 18 o variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell the sinusoidal distribution of the 18 o values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra shell variability reflects seasonal variations of temperature and or salinity average amplitudes of about 5 c in shallow water environments and of about 2 3 c in deeper offshore environments are calculated these amplitudes reflect minimum seasonal temperature variation our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite 18 o data and are in better agreement with paleontological data more specifically a warming trend of about 3 c is reconstructed for oceanic surface waters during the early to middle oxfordian transition with maximum temperatures reaching 24 c in the transversarium zone late middle oxfordian from the transversarium zone to the bimmamatum zone a cooling of about 7 c is indicated whereas from the bimmamatum zone temperatures increased again by about 7 c to reach 24 c in average during the cymodoce zone early kimmeridgian

late cretaceous paleogene palaeoclimate reconstruction of the gippsland basin se australia abstract the cretaceous paleogene palaeovegetation and palaeoclimate in the gippsland basin was reconstructed using vascular plant derived biomarkers and are consistent with other proxy evidence for palaeoclimate e g spore pollen assemblages and plankton foraminifera oxygen isotopes variation in the higher plant derived aliphatic and aromatic sesquiterpenoids diterpenoids and triterpenoids resulted from vegetation succession and is different in the t lilliei f longus l balmei m diversus p asperopolus and n asperus palynological biozones analyses of the oleanane index the higher plant parameter the higher plant index the higher plant fingerprint and various aliphatic and aromatic angiosperm gymnosperm indices indicate the late cretaceous paleogene ca 80 40 ma palaeoclimate in the gippsland basin was initially warm campanian t lilliei biozone and then changed in this way cool maastrichtian upper f longus biozone warm paleocene l balmei biozone hot early eocene m diversus and p asperopolus biozones warm and then cool middle eocene n asperus biozone this changing climate trend is mostly consistent with global climate changes in comparison to the analogous taranaki basin western new zealand the gippsland basin is inferred to have had a less gymnosperm dominated rainforest and a warmer climate in the late cretaceous during the paleogene the palaeoclimate was similar in the two basins as deduced from the angiosperm gymnosperm indices of the sedimentary rocks

geodynamic settings and tectonic model of skarn gold deposits in china an overview seventy skarn type gold deposits including 1 super large 19 large and 24 medium sized are known from different geotectonic units of china they contain a total resource of approximately 1000 t of gold 625 t in south china and account for 20 of china s gold reserves these skarn deposits are sited in collisional orogenic belts fault controlled magmatic belts and reactivated cratonic margins all of the chinese skarn gold provinces were affected by phanerozoic collisional orogenesis the timing of the metallogenic events and the spatial temporal distribution of the chinese skarn gold deposits indicates that they were formed during ore forming processes linked to the transition from shortening to extension in the geodynamic evolution of a collision orogen and not to subduction systems as is commonly advocated for porphyry copper systems around the pacific rim

aliphatic and aromatic triterpenoid hydrocarbons in a tertiary angiospermous lignite abstract the hydrocarbon biomarker assemlage of a liptinite rich early tertiary angiospermous lignite has been characterized the biomarker fistribution for the lignite confirms the low maturity and previous paleobotanic interpretations the aliphatic hydrocarbon fraction consists predominantly of n alkanes showing a strong odd carbon predominance and numerous de a triterpenoids and triterpenoids derived from higher plants bacterially derived triterpenoids were represented primarily by homohopanes and hopenes the aromatic hydrocarbon fraction contains a series of mono di and triaromatic de a triterpenoids and mono tri and tetraaromatic triterpenoids derived from higher plants the concentration and abundance of monoaromatic triterpenoids containing one to three additonal degress of unsaturation have not seen previously observed in a single deposit as such a diagenetic scheme for angiosperm derived triterpenoids is presented which confirms and extends previous hypothesis

geology geochronology and geochemistry of the dabate cu mo deposit northern chinese tien shan implications for spatial separation of copper and molybdenum mineralization abstract the dabate deposit is a porphyry cu mo deposit located in the sailimu block northern chinese tien shan the deposit shows a clear separation of cu and mo mineralization with cu mineralization occurring along the edge of the rhyolitic porphyry and mo mineralization in the inner part of the rhyolitic porphyry sm nd isotopic analyses of six fluorite samples from the cu sulfides fluorite veins yield an isochron age of 298 1 5 0 ma and re os isotopic analyses of four molybdenite samples from the molybdenite quartz veins yield an isochron age of 299 6 3 2 ma these geochronological data and accompanying geologic evidence indicate that the cu and mo mineralization belongs to the same hydrothermal system and are closely related to the rhyolitic porphyry which has a youngest zircon 206pb 238u age of 297 3 8 0 ma rare earth element ree and fluid inclusion studies were carried out for fluorite in the cu ores the fluorite related to cu mineralization have high ree 63 4 216 9 ppm and show generally similar ree patterns with the rhyolitic porphyry suggesting that the fluid of cu mineralization is closely related to the rhyolitic porphyry the slight lree depletion and ce depletion of fluorite relative to the rhyolitic porphyry may be due to preferential partitioning of hree into the fluid in neutral to weak alkaline conditions and to mixing with meteoric water which is characterized by ce depletion three types of fluid inclusions were recognized in the fluorite from the cu sulfides fluorite veins liquid vapor lv type co2 bearing c type and solid mineral bearing s type the lv type inclusions have homogenization vapor to liquid temperatures from 175 to 328 c and salinities of 0 4 14 9 wt nacl eqv mode at 0 8 wt nacl eqv and is of h2o nacl composition the c type inclusions have homogenization vapor to liquid temperatures from 206 to 279 c and salinities of 1 6 8 5 wt nacl eqv and is of h2o co2 nacl ch4 composition the s type inclusions have partial homogenization vapor to liquid temperatures of 173 233 c and salinities of 1 2 7 9 wt nacl eqv and is of h2o nacl composition the solid particle in s type inclusions did not change during heating up to 550 c indicating that the solid is not daughter mineral and the s type inclusions are actually the same as the lv type inclusions the lv type inclusions have microthermometric attributes similar to those typically found in the late stages of porphyry deposits whereas the c type inclusions have similar compositions as the inclusions in the mo ores as documented in previous studies at dabate the presence of both lv type and c type inclusions suggests that the cu mineralization may be related to mixing between meteoric water and magmatic fluids as is also indicated by the ree of fluorite comparing with data from mo ores reported in previous studies it is suggested that the mo stage fluids were more reduced and acidic and mo mineralization may be mainly related to fluid pressure decrease and immiscibility whereas the cu stage fluids were more oxidized neutral to weakly alkaline and cu mineralization may be mainly controlled by mixing and cooling the vapor phase produced by fluid immiscibility in the deep area may have carried cu as ag hf co2 and migrated to the outer part of the porphyry precipitated cu sulfides arsenopyrite and fluorite by mixing with meteoric water from the country rocks whereas the liquid phase produced by fluid immiscibility at depth may have carried mo nacl and migrated to the middle west part of the rhyolitic porphyry become immiscible and precipitated molybdenite

polycyclic aromatic hydrocarbons of pyrolytic origin in ancient sediments evidence for jurassic vegetation fires abstract polycyclic aromatic hydrocarbon pah distributions in an upper jurassic succession from offshore korea bay basin were consistent with a pyrolytic source being dominated by non alkylated species levels of these pahs were significantly higher in samples containing abundant fusinite macerals which are believed by some to be the product combustion the data were consistent with a pah origin from periodic conflagration throughout the upper jurassic of vegetation adjacent to a tectonically formed lake distribution of pahs exhibited some differences from those of combustion origin in recent and some ancient sediments and were characterized by the dominance of the highly peri condensed compounds benzo e pyrene benzo g h i perylene and coronene this characteristics reflects either preferential formation or preferential preservation under the prevailing sedimentary conditons of the highly peri condensed structures

sesqui and diterpenoid biomarkers preserved in taxodium rich oligocene oxbow lake clays weisselster basin germany several diterpenoids of the abietane pimarane and phyllocladane type and three cadalanetype sesquiterpenoids have been identified in the organic solvent extracts of lower oligocene clay sediments haselbach strata saxony germany the sediment contains needles and cone scales of a fossil taxodium species which represents the only conifer in the samples a clear correlation between the observed conifer biomarkers and taxodium is evident apart from diterpenoids detected previously in other sediments a new diaromatic totarane diterpenoid is reported in isolated fossil and recent taxodium needles and cone scales as well as in the haselbach clays a phenolic diterpenoid of the abietane type ferruginol has been identified the results indicate that the taxodium rich clay samples contain several diterpenoids which so far have been used as biomarkers for other conifer families and thus the chemotaxonomical use of diterpenoid biomarkers for the differentiation of fossil conifer families has to be revised

chemostratigraphic evidence of higher plant evolution in the taranaki basin new zealand correlation between palynological and biomarker records of higher plant development during the cretaceous and paleogene in taranaki basin new zealand is good gymnosperms particularly podocarps were the chief members of coastal plain swamp flora during the late cretaceous and contributed significant quantities of diterpanes often dominated by isopimarane to organic rich sediments angiosperms increased in relative abundance through the paleocene and became the dominant higher plants in the eocene their contributions to coaly sediments are characterized by various triterpanes particularly 18 h oleanane and its c24 a ring degraded counterpart this change in dominance of higher plant groups can be followed by the use of an angiosperm gymnosperm index agi based on the relative concentrations of selected triterpanes and diterpanes in mz 191 and mz 123 mass chromatograms plant biomarker distributions do not provide as precise age indications as do pollen assemblages but they may be more representative of the vegetation growing in a particular area of a peat swamp

petroleum potential and kinetic models for hydrocarbon generation from the upper cretaceous to paleogene latrobe group coals and shales in the gippsland basin australia abstract pyrolysis experiments open and closed systems and kinetic modelling of primary cracking of kerogen have been carried out to investigate hydrocarbon generation characteristics and source rock facies variability within the upper cretaceous to paleogene latrobe group in the gippsland basin on the basis of rock eval data the interbedded coals coaly shales and carbonaceous shales contain different types of kerogen type iii type ii iii type ii with variable potential for both gas and liquid hydrocarbon generation open system pyrolysis gas chromatography data indicate that the organically lean marginal marine shales of the santonian early campanian tricolporites apoxyexinus and nothofagidites senectus biozones produce gas and condensate however coal and coaly to carbonaceous shales sampled from the paleocene lygistepollenites balmei maastrichtian forcipites longus late campanian tricolporites lilliei and turonian phyllocladidites mawsonii palynological biozones are heterogeneous with the capacity to generate both low and high wax paraffinic naphthenic aromatic p n a oils and paraffinic oils with a high wax content the main phase of petroleum formation from these later biozones assuming a constant geological heating rate of 3 3 c ma is predicted to occur between 150 179 c indicating different orders of kinetic stability as a result of different types of organic matter and their state of preservation the thermally immature shales have variable bulk kinetic characteristics but the measured compositional kinetics and phase behaviour show that they have the potential to generate black oils at early stages of kerogen cracking and either light oils or wet gases at higher levels of thermal stress these findings suggest that upon thermal maturation the interbedded shales of the latrobe group may have contributed significant volumes of hydrocarbons to the oil and gas accumulations in the gippsland basin in addition this study not only supports the premise that over reliance on rock eval toc data alone can be misleading for assessment of petroleum generation but also represents a strategy for kerogen type and generative potential determination for fluvio deltaic coals and subordinate lithologies

occurrence and palaeoenvironmental significance of aromatic hydrocarbon biomarkers in oligocene sediments from the mallik 5l 38 gas hydrate production research well canada abstract the aromatic hydrocarbon biomarker distributions of thirty oligocene sediment samples with different lithology lignite clay and sand from the japex jnoc gsc et al mallik 5l 38 gas hydrate production research well canada were analyzed using gas chromatography mass spectrometry gc ms the compositions vary with lithology indicating a change in palaeoenvironmental conditions at the time of deposition aromatic diterpenoids of the abietane type are more abundant in the lignite samples than in the clay samples and represent a gymnosperm e g conifer dominated palaeovegetation in contrast in the clay samples aromatic triterpenoids are generally preserved as major constituents indicating angiosperm dominated vegetation the sand samples contain only minor amounts of aromatic terpenoids but show a preference for diterpenoid gymnosperm markers to recognise gymnosperm versus angiosperm dominated palaeoenvironments a new ratio termed the angiosperm gymnosperm aromatic ratio agar has been developed thus the terpenoid distribution in the deltaic sediments provides information on the compositional changes in the plant community at the mallik site lignites and the hinterland clays over time concomitantly the changing dominance in the plant communities allows an insight into varying climatic conditions during the late oligocene in the area additionally the aromatic biomarker composition has been used to assess the level of thermal maturity of the organic matter in the mallik samples and indicates a prevailing immature character

can economic porphyry copper mineralization be generated by a typical calc alkaline melt numerical simulation of chlorine and copper partitioning between a crystallizing melt and exsolving aqueous fluids indicates that typical calc alkaline magmas contain sufficient copper chlorine and water to produce economic porphyry copper mineralization neither an elevated copper content in the magma nor an additional large volume of magma are required to provide metals or volatiles the most important variables that determine the volume of melt necessary to produce sufficient copper are the degree of compatible behavior displayed by copper the ratio of initial water in the melt to the water saturation level and the initial chlorine water ratio of the melt the absolute values for initial water in the melt and water content at saturation are relatively unimportant in determining the required melt volume the bulk salinity of the exsolved fluid may vary from 2 0 wt nacl to saturation levels 84 wt nacl at 700 c indicating that boiling is not necessary to produce high salinity brines at appropriate p t xnacl conditions the magmatic aqueous fluid separates into a saline liquid which transports most of the copper and a low salinity vapor the salinities of the two immiscible phases are governed by the p t conditions while the bulk fluid salinity determines the mass fractions of liquid and vapor formed pressure quenching causes rapid crystallization of the aplitic groundmass in porphyritic rocks associated with copper mineralization and significantly reduces the amount of chlorine and copper partitioning to the aqueous fluid this results in abrupt and possibly large reductions in fluid salinity and causes copper to become concentrated in the melt as copper is transported from the melt by the earliest exsolving fluids in deep 2 0 kbar systems and by late exsolving fluids in shallow 0 5 kbar systems the relative timing of pressure quenching aplite formation and fluid transport of copper from the melt can vary significantly in systems produced under different confining pressures model results incorporating petrologic constraints determined for yerington nevada are in good agreement with observed mineralization

origin of mesozoic and tertiary granite in the western united states and implications for pre mesozoic crustal structure 2 nd and sr isotopic studies of unmineralized and cu and mo mineralized granite in the precambrian craton in the cordilleran region of the western united states mesozoic and tertiary peraluminous granitic rocks display regional variations in initial 143nd 144nd end end 10 to 12 in southern arizona 17 to 19 in the northern great basin ngb and 30 in the northern rocky mountains initial 87sr 86sr values are between 0 710 and 0 721 and show no regional pattern metaluminous granitic rocks have a wider range of end values extending from values similar to those of the peraluminous granites to much higher values the 87sr 86sr values are mostly fairly low between 0 705 and 0 710 except in the ngb where values as high as 0 7157 are observed no systematic differences between the end or 87sr 86sr values of cu or mo mineralized and unmineralized granite were discerned except for cu mineralized granite in eastern nevada and mo mineralized granite in colorado which have end values higher 0 and lower 10 0 respectively than unmineralized granite in the same region comparison to end values of exposed precambrian rock suggests that the peraluminous granite and the mo granite in colorado were derived exclusively from felsic precambrian basement rocks and that the regional variations in the end values reflect the regional variation in the average crustal age the nd data confirm that the precambrian basement underlying the ngb and eastern california is isotopically distinct from precambrian crust in the remainder of the western united states the similarity between the end values of peraluminous granite and precambrian crust also suggests that the high 147sm 144nd 0 13 and the low total light rare earth element lree abundances characteristic of peraluminous granite in southern arizona were imposed during the chemical evolution of the magmas metaluminous granite are interpreted to have formed via mixing of mantle derived magma and large proportions of low 87sr 86sr granulite facies lower crust except in the eastern ngb where the mantle magmas mixed with a lower crustal source with a significantly higher 87sr 86sr ratio ree abundance patterns for metaluminous granite in the ngb are characterized by extreme lree enrichment which supports the proposed origin for these rocks by mantle crust mixing or by remelting of the lower crust alone no systematic difference exists between the sources of cu or mo mineralized and unmineralized metaluminous granite but the data suggest that the cu sources are in the mantle and the mo sources are in preexisting crust overall the nd data indicate that continental interior granite in the western united states was primarily derived from preexisting crust and although changes in the thermal structure of the continental mantle may have triggered magma formation the resulting granites do not represent significant juvenile additions to the continental crust

organic geochemistry in a sequence stratigraphic framework the siliciclastic shelf environment of cretaceous series se france for a better understanding of siliciclastic shelf environments correlation between sequence stratigraphy and organic geochemistry is used our study is focused on the cretaceous deposits of marcoule gard france particularly on a close packed siltites layer 200 400 m thick which is well characterized as a marine flooding facies of a single trangressive regressive cycle during the uppermost albian and the lower cenomanian the stratigraphic data indicate a change in the depositional environment from offshore to shoreface organic geochemistry is used in order to characterize origin and variability of the organic matter in relation to the stratigraphic data the study is carried out on core samples from 2 drill holes mar 203 and mar 501 analyses of the aliphatic and aromatic hydrocarbons were performed using gc ms and focused on biomarker distributions the biomarkers indicate a contribution of mixed terrestrial and marine organic matter the changes in molecular signatures are related to variations in the source of organic matter marine versus terrestrial preservation conditions largely influenced by clay and early diagenesis environmental oxidation reduction and acidic conditions as well as bioturbation various environmental zones characterized by different molecular signatures can be distinguished resin derived biomarkers can be assigned to higher plant material input and may reflect the evolution and diversity of gymnospermae versus angiospermae during the transgressive regressive cycle the relative sea level variations are clearly correlated with the nature and the preservation of the organic matter for example the pr ph and pr n c 17 ratios as well as the regular steranes distributions underline the maximum flooding surface evidenced by other studies we observe a good correlation between the organic data and sequence stratigraphy changes in geochemical signatures reflect the 3rd order depositional cycles

configurational isomerization in sedimentary bicyclic alkanes the soluble organic matter and pyrolysate from a sample suit of triassic sediments have been analyzed by gc ms techniques for c 8 epimers of drimane and homodrimane the relative abundance of epimers is maturity dependent compounds with the 8 h configuration being dominant in more mature samples these changes have been attributed to isomerization reactions which result in apparent equilibration of epimers before the onset of significant hydrocarbon generation

evolution of calc alkaline to alkaline magmatism through carboniferous convergence to permian transcurrent tectonics western chinese tianshan continuous magmatic activity occurred in the western chinese tianshan central asia from the carboniferous to the permian i e before and after the late carboniferous amalgamation of junggar and the yili blocks zircon u pb la icpms and ar ar data reveal a coincidence in time between regional wrench faulting and granitoid emplacement permian post collisional granitoids crop out within or at the margins of large scale dextral strike slip shear zones some of them show synkinematic fabrics the whole rock geochemical features of the early middle permian granitoids indicate an evolution from high k calc alkaline towards alkaline series in other places of the north tianshan alkaline magmatism occurred together with deep marine sedimentation within elongated troughs controlled by wrench faults therefore in contrast with previous interpretations that forwarded continental rift or mantle plume hypotheses the coexistence of diverse magmatic sources during the same tectonic episode suggests that post collisional lithosphere scale transcurrent shearing tightly controlled the magmatic activity during the transition from convergent margin to intraplate anorogenic processes

geochronology and fluid inclusion studies of the lailisigaoer and lamasu porphyry skarn cu mo deposits in northwestern tianshan china abstract the lailisigaoer porphyry mo cu and lamasu porphyry skarn cu deposits are located in the northwestern tianshan orogenic belt which is in the northwestern china according to re os analysis of molybdenite the time of mineralization of the lailisigaoer deposit is 377 ma and shrimp zircon u pb analysis dates the ore hosted intrusion of the lamasu deposit to 378 ma five types of fluid inclusions fis have been identified in both deposits h 2 o rich inclusions co 2 bearing inclusions halite bearing inclusions methane rich inclusions and pure co 2 inclusions in the lailisigaoer deposit the early stage fluid of the quartz phenocryst belongs to a nacl h 2 o system with total homogenization temperatures t h ranging from 300 to 395 c with a mean salinity of 9 0 wt nacl in the ore forming stage the fluid develops into a h 2 o nacl co 2 system due to boiling and decarbonation the t h values and salinities cluster between 220 and 370 c and between 0 and 33 0 wt nacl respectively the hydrothermal characteristics of the late quartz calcite stage are similar to those of the meteoric fluid in the lamasu deposit the early stage fluid of the quartz phenocryst belongs to a nacl h 2 o system with t h values ranging from 245 to 459 c and a mean salinity of 6 0 wt nacl in the ore forming stage due to the contact metamorphism between the hydrothermal fluid and wall rock the fluid evolves to a nacl h 2 o ch 4 system the t h values and salinities cluster between 220 and 360 c and between 0 and 17 3 wt nacl respectively the fluid of the late quartz sulfide stage coincides with the meteoric fluid in the mineralizing fluid of the lailisigaoer deposit the captured temperatures and pressures are between 210 and 350 c and between 170 and 600 bars respectively which are consistent with fluctuation between hydrostatic and lithostatic pressure corresponding to the estimated paleodepths of 1 7 2 2 km boiling is the dominant mineralizing mechanism in the lailisigaoer deposit whereas the contact metamorphism between the magmatic hydrothermal fluid and country rocks is the dominant mechanism in the lamasu deposit both deposits are formed in the continental arc setting related to the southward subduction of the north tianshan oceanic slab beneath the yili central tianshan block

geochemical comparison of three oil families from the gippsland basin se australia abstract the biomarker and aromatic compounds including polycyclic aromatic hydrocarbons pahs in three oil families composed of 29 crude oils from the gippsland basin se australia were studied using gas chromatography mass spectrometry environment related parameters such as the pr ph ratio and the gammacerane index indicate that all the oils originated from a lacustrine fluvial deltaic environment with fresh water thermal maturity related parameters including aliphatic and aromatic maturity indicators e g c29 sterane isomerisation parameters alkylnaphthalene indices and methylphenanthrene index show that all the oils from the ga1 oil family have a similar thermal maturity in the peak late oil window however oils from the ga2 and gb families vary in thermal maturity and are interpreted to be mixtures of less mature and more mature crude oils source related biomarkers e g isopimarane labdane and phyllocladane and pahs e g retene and oleanane ursane lupane derived aromatic triterpenoids suggest that the ga1 oils were mainly derived from source rocks rich in conifer derived organic matter the organic matter source of the ga2 and gb oil families included both angiosperms and gymnosperms with a relatively stronger angiosperm contribution to the organic matter in the source rock s of the gb oils based on the pah analysis moreover higher plant derived triterpenoids can be effectively used to correlate oil families across the study area supplementing the n alkane carbon isotope and biomarker data of the three oil families reported previously

polycyclic aromatic hydrocarbons in ancient sediments and their relationships to palaeoclimate combustion derived and land plant derived polycyclic aromatic hydrocarbons pahs have been investigated for an upper triassic to middle jurassic sedimentary sequence from the northern carnarvon basin western australia the former included fluoranthene pyrene benzofluoranthenes benzo e pyrene and benzo a pyrene and the latter included retene cadalene and simonellite combustion derived pahs are most abundant in the upper triassic and late lower jurassic sediments the abundances of land plant derived markers all maximise in the upper part of the lower jurassic section but vary independently of one another through time the changes in the relative abundances of these markers have been related to the variation of regional climatic conditions especially the changes in humidity and seasonality during the late triassic to middle jurassic times

evolution of hydrothermal fluid characteristics at the santa rita new mexico porphyry copper deposit mineralogic and fluid inclusion investigations conducted in the laboratory combined with in situ observations of temporal relationships among geologic features demonstrate that systematic changes in hydrothermal fluid characteristics occurred with time during evolution of mineralization and alteration of the granodiorite stock at the santa rita porphyry copper deposit the earliest fluids to circulate are recorded in potassically altered orthoclase and biotite stable veins as vapor rich h 2 o co 2 inclusions and hypersaline 30 70 equiv wt nacl or kcl inclusions which homogenize over a wide temperature range from 240 degrees to greater than 800 degrees c the high salinity fluid inclusions are complex chloride brines with significant concentrations of sodium potassium copper iron and sulfur but sulfide minerals are not associated with the early potassic assemblage produced by this fluid oxygen isotope ratios of quartz in the orthoclase and biotite stable veins are identical to phenocryst quartz in the intrusion 8 2ppm later solutions circulated through newly formed fractures and older reopened veins and are recorded in low salinity less than 15 equiv wt nacl fluid inclusions which homogenize primarily in the temperature range of 220 degrees to 360 degrees c these hydrothermal fluids formed two distinct alteration assemblages as they reacted with potassically altered rock chlorite is the dominant silicate gangue mineral of the earlier chalcopyrite bearing orthoclase and clay stable assemblages and sericite characterizes the later phyllic alteration assemblage with quartz and pyrite oxygen isotope ratios of quartz of the later assemblages 8 6 10 4ppm are heavier than quartz of the earlier potassic assemblages it is concluded that the earliest hydrothermal fluids to circulate within the stock localizing the orebody at santa rita could have been derived by phase separations of fluids exsolved from crystallizing magma into condensed hypersaline liquids and h 2 o co 2 vapors as these fluids moved through fractures potassic alteration of rock occurred without concomitant deposition of sulfides later solutions of dominantly meteoric origin progressively formed hypogene copper mineralization associated with chlorite stable alteration and then phyllic alteration

the origin of ch4 rich fluids in reduced porphyry skarn cu mo au systems abstract although most of the methane on earth is of biogenic origin significant abiogenic methane has been identified in a variety of geological environments moreover the presence of methane has been reported recently in fluid inclusions from a number of reduced porphyry deposits the genesis of this methane however remains poorly understood here we present results of a study of magma exsolved ch4 rich aqueous fluid inclusions in the seleteguole reduced porphyry skarn cu mo au deposit nw china four types of fluid inclusions namely intermediate density two phase aqueous inclusions low density vapor inclusions brine inclusions and aqueous liquid inclusions have been distinguished on the basis of the phases present at room temperature the intermediate density inclusions were trapped as a single phase and contain 3 8 10 4 mol kg ch4 corresponding to an oxygen fugacity between fmq 1 and fmq 0 5 this attests to the remarkably reduced nature of the fluid the 13c value of the ch4 hosted fluid inclusions ranges from 29 4 to 19 1 pdb which distinguishes this methane from biogenic methane indeed the high homogenization temperature of the ch4 rich inclusions 400 c implies that the ch4 was exsolved directly from the magma given the environment in which the magma was likely generated i e at or immediately above a subducting plate we propose that the methane was produced by reactions involving organic matter bearing carbonate rocks in the subduction zone although cu mo and au in most porphyry systems are interpreted to have been transported under oxidizing conditions our results indicate that reduced aqueous liquids and vapors are also capable of transporting appreciable concentrations of these metals

geology s pb o and h isotopic compositions and re os chronology of kendenggaoer cu mo deposit in xinjiang located in bolohuoluo palaeozoic arc belt the kendenggaoer cu mo deposit has aroused much attention among geologists the ore bodies in the tabular laminated and lenticular forms occur in the outer contact zone between late carboniferous granodiorite and upper carboniferous carbonate rocks metallic minerals in the ore include mainly chalcopyrite and molybdenite while gangue minerals are mainly diopside and andradite sulfide minerals existing as euhedral or xenomorphic crystals with stockwork and dissemination structures are distributed in the skarn rocks endogenic ore forming process has obviously experienced two stages of mineralization i e skarn and quartz sulfide 34sv cdt values of molybdenite and chalcopyrite in the ore vary from 0 55 to 1 90 concentrated around zero the ratios of 206pb 204pb 207pb 204pb and 208pb 204pb are from 17 963 to 18 256 15 549 to 15 605 and 36 802 to 38 271 respectively suggesting that metallogenic materials are derived from both upper mantle and lower crust 18oh2o v smow and dh2o v smow values of quartz as well as the water in the inclusions from the cu mo ores of the quartz sulfide stage are from 2 82 to 3 65 and from 96 to 82 respectively implying that ore forming fluids were mainly magmatic water with the mixture of small quantities of precipitate water re content of molybdenite in cu mo ores is in the range of 11 13 59 72 g g isochron dating of re os is 313 9 2 5 ma indicating that the metallogenic age is late carboniferous therefore the ore forming process was related to the southward subduction of the yilianhabierga oceanic basin in the middle of early carboniferous

genesis of the yandong porphyry cu deposit in eastern tianshan nw china evidence from geology fluid inclusions and isotope systematics abstract the yandong porphyry cu deposit 372 mt at 0 58 cu is located in the center of the eastern tianshan xinjiang nw china multiple stage hydrothermal activities have resulted in potassic chlorite sericite phyllic and propylitic alteration in this deposit the yandong deposit formed in four stages i e an early quartz magnetite pyrite stage i a quartz pyrite chalcopyrite stage ii a quartz chalcopyrite pyrite molybdenite stage iii and a late quartz carbonate stage iv three evolutionary episodes were observed by a detailed fluid inclusion study 1 early ore stage i fluids were trapped under two phase conditions as evidenced by the coexistence of vapor rich v type inclusions homogenization temperatures 410 494 c average salinity 2 2 wt nacl equiv liquid rich l type inclusions homogenization temperatures 311 430 c average salinity 9 5 wt nacl equiv and hypersaline h type inclusions trapped at 300 bars or a depth of approximately 1 km assuming lithostatic pressure conditions 2 main ore stage ii and iii fluid inclusions in quartz were also trapped under two phase conditions boiling as identified by the coexistence of v and l type fluid inclusions l type inclusions homogenized between 161 and 390 c average 270 c with salinities of 1 6 9 9 wt nacl equiv average 4 9 wt nacl equiv and a depth of 1 km 100 bars hydrostatic pressure conditions 3 late ore stage iv fluids are represented by inclusions in barren quartz carbonate veinlets characterized by homogenization temperatures ranging from 123 to 261 c average 179 c and salinities between 0 7 and 4 7 wt nacl equiv average 2 0 wt nacl equiv the initial hydrothermal fluids are characterized by high temperature high salinity and high oxygen fugacity belonging to a h 2 o nacl system hydrogen and oxygen isotope data indicate that the hydrothermal fluids have a dominantly magmatic signature and mixed with abundant meteoric waters in the quartz carbonate stage sulfur stable isotope suggests that the ore forming metals came primarily from the tonalite magma that sourced from the subducted oceanic slab involving some mantle peridotites during ascent the cu mineralization of the yandong porphyry deposit occurred at a shallow crustal level approximately 1 km and the fluid boiling or phase separation decrease of temperature as well as fluid rock interaction were likely important factors responsible for metal accumulation and deposition in the magmatic hydrothermal system

cretaceous sea surface temperature evolution constraints from tex86 and planktonic foraminiferal oxygen isotopes it is well established that greenhouse conditions prevailed during the cretaceous period 145 66 ma determining the exact nature of the greenhouse gas forcing climatic warming and climate sensitivity remains however an active topic of research quantitative and qualitative geochemical and palaeontological proxies provide valuable observational constraints on cretaceous climate in particular reconstructions of cretaceous sea surface temperatures ssts have been revolutionised firstly by the recognition that clay rich sequences can host exceptionally preserved planktonic foraminifera allowing for reliable oxygen isotope analyses and secondly by the development of the organic palaeothermometer tex86 based on the distribution of marine archaeal membrane lipids here we provide a new compilation and synthesis of available planktonic foraminiferal 18o 18opl and tex86 sst proxy data for almost the entire cretaceous period the compilation uses ssts recalculated from published raw data allowing examination of the sensitivity of each proxy to the calculation method e g choice of calibration and places all data on a common timescale overall the compilation shows many similarities with trends present in individual records of cretaceous climate change for example both sst proxies and benthic foraminiferal 18o records indicate maximum warmth in the cenomanian turonian interval our reconstruction of the evolution of latitudinal temperature gradients low 48 palaeolatitudes reveals temporal changes in the valanginian aptian the low to higher mid latitudinal temperature gradient was weak decreasing from 10 17 c in the valanginian to 3 5 c in the aptian based on tex86 ssts in the cenomanian santonian reconstructed latitudinal temperature contrasts are also small relative to modern 14 c based on low latitude tex86 and 18opl ssts minus higher latitude 18opl ssts compared with 20 c for the modern in the mid campanian to end maastrichtian latitudinal temperature gradients strengthened 19 21 c based on low latitude tex86 and 18opl ssts minus higher latitude 18opl ssts with cooling occurring at low middle and higher palaeolatitude sites implying global surface ocean cooling and or changes in ocean heat transport in the late cretaceous these reconstructed long term trends are resilient regardless of the choice of proxy tex86 or 18opl or calibration this new cretaceous sst synthesis provides an up to date target for modelling studies investigating the mechanics of extreme climates

origin of the subduction related carboniferous intrusions associated with the yandong porphyry cu deposit in eastern tianshan nw china constraints from geology geochronology geochemistry and sr nd pb hf o isotopes the yandong porphyry cu deposit is located at the south margin of the dananhu tousuquan arc belt in eastern tianshan northwest china the cu ores comprise mainly disseminations and vein zones in the potassic and phyllic alteration zones and are predominantly hosted in diorite porphyry tonalite and quartz porphyry which intruded into carboniferous qi eshan group volcanic rocks the u pb ages indicate that four intrusions were emplaced between 338 6 2 9 and 326 1 2 6 ma five molybdenite samples yield re os model ages of 333 8 329 5 ma with a weighted average age of 331 8 2 1 ma fourteen pyrite samples have 206pb 204pb of 17 776 18 959 207pb 204pb of 15 410 15 534 and 208pb 204pb of 37 323 38 127 similar to the age corrected data of the yandong tonalite the tonalite shows adakite like characteristics e g high sr y ratios and low y contents and has positive end t and ehf t values and low zircon o isotopes 3 7 4 6 suggesting that the melt was derived from partial melting of a subducted oceanic slab followed by mantle peridotite interaction the diorite porphyry exhibits high mg and low sr y values slightly negative eu anomalies and positive ehf t values indicating a lithospheric mantle source the quartz porphyry with stronger negative eu anomalies less evolved ehf t values and low 18o values 4 7 5 5 was probably derived from mantle melts that experienced mixing with lower crustal materials melts or assimilation the new data suggest that the yandong intrusions formed in an arc setting as the tonalite is genetically linked to the cu mineralization subduction related slab melts must have played a key role in the formation of the yandong deposit

middle cambrian to permian subduction related accretionary orogenesis of northern xinjiang nw china implications for the tectonic evolution of central asia abstract middle cambrian to permian subduction related records are widely distributed in northern xinjiang which can be grouped into the chinese altay east junggar eastern tien shan west junggar yili and tarim domains by integrating paleogeographic and geological data we suppose that the chinese altay east junggar eastern tien shan domain was more closely located to siberia while the west junggar and yili domains occupied an intermediate position near the kazakhstan block in the early paleozoic paleoasian ocean distribution of andean type magmatic arcs island arcs accretionary wedges ophiolitic slices and or microcontinents shows an archipelago paleogeography forming a huge accretionary active margin sequences the tarim domain was on the opposite side of the early paleozoic paleoasian ocean remaining passive margin these tectonic units drifted northwards and approached the southern active margin of the siberian craton in the late paleozoic leading to termination of the paleoasian ocean and formation of a complicated orogenic collage between siberian craton and the tarim block between the end permian and triassic these multiple accretion processes significantly contributed to the lateral growth of central asia

petrology and geochemistry of silurian triassic sedimentary rocks in the tongling region of eastern china their roles in the genesis of large stratabound skarn ore deposits abstract this paper describes the petrology and geochemistry of the silurian triassic sedimentary rocks in the tongling area in eastern china aiming to establish a genetic link between different stratabound skarn deposits and sedimentary lithologies the results from this study show that some devonian triassic transitional lithological units with compositions varying between siliceous rock and carbonate especially thinly layered impure carbonate control the distribution of some large stratabound skarn ore deposits in the tongling region interlayer detachment faults in the transitional lithology rocks are particularly important controlling the final locations of the deposits the transitional lithological zones may have also served as source rocks likely providing some ore forming metals to the deposits gypsum evaporites in rocks from carboniferous sources may have supplied some sulphur to the hydrothermal systems five of such transitional lithological units enriched in organic matter are spatially and closely associated with some large stratabound skarn ore deposits in the tongling region suggesting that organic matter may have served as an absorbent or reducing agent during ore formation

reversed magnetic polarity at an early lower palaeolithic site in central italy isernia la pineta central italy is an extensive open air archaeological site of early lower palaeolithic aspect radiometric and palaeomagnetic dating place it in the matuyama reversed epoch hence before 0 73 myr its early date stratified context abundant stone tool industry of choppers and flakes and rich faunal remains make it one of the most important localities for the question of the earliest human colonization of europe the archaeological horizons fig 1 were discovered during recent road building operations at 4 m below surface near the city of isernia upper volturno basin province of molise see fig 2 excavations in 1979 and 1980 carried out in two areas sectors i and ii fig 2 revealed dense scatters of limestone choppers flint flakes and disarticulated bones of large mammals similar occurrences have been found elsewhere in the valley previous accounts1 2 are revised herein

polar aromatic biomarkers in the miocene maritza east lignite bulgaria aromatic and polar compounds of lignite lithotype bitumens maritza east were analyzed diterpenoid phenols and ketophenols i e mainly ferruginol sugiol hinokione and products of their diagenetic transformations were identified as the dominant biomarkers a variety of sesquiterpenoids was present as well these compounds provided evidence for the assumption that members of the cupressaceae s 1 are the coal precursors polar triterpenoids i e lupeol lupenone adiantone and hopanones were present in subordinate quantities in the humoclarain sample these biomarkers support an input of deciduous angiosperm vegetation to the peat swamp source matter three diagenetic transformation schemes for the diterpenoid phenols ketophenols are proposed 1 ferruginol and or sugiol alteration through dehydrogenation demethylation and ring b cleavage 2 hinokione aromatization to simonellite and 3 7 ketototarol change through 7 ketototar 5 enol to 20 nor 3 oxo totara 5 10 6 dienol the identified diterpenoids demonstrated the presence of gymnospermae in the coal forming community furthermore the phenolic diterpenoids indicated a specific input of organic matter from conifers of the cupressaceae taxodiaceae or podocarpaceae as the most abundant trees in the coal forming swamp

geochronology and petrogenesis of miocene granitic intrusions related to the zhibula cu skarn deposit in the gangdese belt southern tibet abstract the zhibula cu skarn deposit 19 5 mt ore 1 64 near the qulong porphyry cu mo deposit is located in the gangdese porphyry copper belt in southern tibet the deposit is a typical metasomatic skarn that is related to the interaction of magmatic hydrothermal fluids and calcareous host rocks stratiform skarn orebodies are mainly distributed in the contact between tuff and marble in the lower part of the jurassic yeba formation endoskarn zonations for an outward trend are observed in the granodiorite which grade from a fresh granodiorite to a weakly chlorite altered granodiorite a green diopside bearing granodiorite and a dark red brown garnet bearing granodiorite the zhibula granodiorite and monzogranite have similar secondary ion mass spectrometry sims zircon u pb ages of 16 9 0 3 ma and 17 0 0 2 ma respectively they exhibit different fractional crystallization from granodiorite sio 2 64 8 69 3 wt to monzogranite sio 2 72 3 76 8 wt both the granodiorite and monzogranite are characterized by high al 2 o 3 12 6 16 7 wt and k 2 o 1 5 5 5 wt contents high sr y 35 151 and la yb 19 48 ratios and variable mgo 0 16 3 91 and mg 31 61 values they display features of enrichment in large ion lithophile elements liles e g rb ba sr and k depletion in high field strength elements hfses e g nb ta ti and p and moderate negative eu anomalies eu 0 58 0 98 they show restricted in situ zircon hf isotopic compositions 6 7 to 8 8 only one sample is 4 5 and consistent 18 o values 6 0 to 6 6 the geochemical data indicated that the miocene zhibula granitic intrusions formed by the magma that were characterized by high sr y ratios and were derived from the partial melting of the thickened juvenile lower crust which may have been metasomatized by the slab melts during subduction of the neo tethyan oceanic crust and were induced by the convective removal of the thickened lithosphere in addition the zhibula cu skarn deposit and the qulong cu mo deposit form a significant porphyry skarn ore system

identification and analysis of dihydro ar curcumene enantiomers and related compounds in petroleum isodihydro ar curcumene 1 1 5 dimethylhexyl 3 methylbenzene has been identified in petroleum using gc ms techniques by comparing its retention time and mass spectrum with the same parameters from a reference compound it co occurs in crude oil with dihydro ar curcumene and is suggested to originate from this compound via a sedimentary rearrangement process enantiomers of both compounds have also been shown to occur in crude oils using chiral gc ms techniques the elution order of the enantiomers has been established using reference compounds of known configuration

middle bathonian floras and phytocoenoses of france abstract in the causses basin se france a continental lignitic deposit yields a diverse middle bathonian megaflora until now almost unstudied the floristic data include megafloras palynology and data from woods and leafy shoots the palaeoecology of this flora is quite unique representing backswamps fens and freshwater ponds in a carbonate domain there is little evidence of vegetation from brackish environments elsewhere in france contemporaneous floras are known with different ecologies these include a flora of low undulating tracts on shell sand in normandy and a mangal assemblage in franche comte new palaeobotanical and palynological data are given for both floras the floristic composition of the three floras is compared and discussed together with additional coeval data this set of floras is of interest as they grew mainly on calcareous soils whereas most middle jurassic floristic associations described previously were mainly from siliciclastic environments because of their contemporaneous nature asserted with an accuracy rarely reached for continental biota these floras can be used to estimate the climatic gradient of the middle bathonian

amino acid racemization dating of quaternary deposits of central and southern italy abstract results are discussed of amino acid racemization dating of numerous samples of bones teeth tooth enamel and fossil shells racemization dating proved to be a very useful tool to date non marine and marine deposits which are a few hundred thousand years old as well as to correlate and chronologically classify even more ancient marine deposits aspartic acid racemization was used to date samples aged less than 80 000 100 000 yr for more ancient samples isoleucine epimerization instead was resorted to in this work dates were established for some important fragments of human bones and of large mammalian fauna weighing a few grams which would have been impossible to date with the 14 c technique requiring a large amount of bone material the extent of isoleucine epimerization was measured in glycymeris genera to estimate the age of numerous marine deposits of the tyrrhenian coast of centra southern italy and of sardinia in the tarquinia area latium three marine terraces were identified which were estimated to be approx 120 000 200 000 and 350 000 yr old in sardinia five marine horizons were identified the youngest deposit neotyrrhenian proved to be present at punta tramontana and santa reparata while at riola and stagno di sassu the most ancient marine deposits of sardinia were found in the rome area the monte mario formation was estimated to be coeval with monte delle piche formation finally from the terraced coastal deposits of capo milaazzo sicily panarea eolian archipelago archi calabria and gallipoli apulia a tyrrhenian age range of 100 000 120 000 yr was obtained

retrograde fluid evolution at the rampura agucha pb zn ag deposit rajasthan india fluid inclusions in mineralized graphite sillimanite mica schist from the rampura agucha pb zn ag deposit rajasthan northwest india have been investigated by microthermometry and raman microspectrometry three different main types of fluid inclusions in quartz can be distinguished 1 gaseous co2 partially mixed with ch4 n2 2 low salinity aqueous inclusions 0 8 eq wt nacl and 3 high salinity aqueous inclusions nacl mgcl2 cacl2 low density co2 rich and low salinity h2o inclusions are contemporaneous and occur together with ch4 n2 inclusions in close association with sulfide mineral inclusions this indicates immiscibility between the gaseous and aqueous phase and participation of these fluids during the deposition or remobilization of the ore which occurred over a wide p 1220 to 200 bar and t 450 to 250 c raman spectra of graphite indicate upper greenschist facies metamorphic conditions although host rocks have been metamorphosed at upper amphibolite facies metamorphic conditions this indicates that graphite re equilibrated with the co2 rich phase during retrograde metamorphism

a geochemical appraisal of oil generation in the taranaki basin new zealand from a basin wide evaluation of organic geochemical data it has been possible to characterize and differentiate various source rock units and to establish the genetic relationships of oils most of the oils are primarily terrestrially sourced and it is possible to recognize varying contributions from source rocks within the paleogene kapuni group and late cretaceous pakawau group this distinction is attributable to the rise to dominance of angiosperms over gymnosperms in coastal plain swamp communities by the eocene apart from the maui family i e maui field maui 4 and moki 1 oils the inferred relative contributions from the main source rock types generally correlate with the relative proportions of suitably thick and mature units near reservoirs given that mos cretaceous sourced oil appears to have escaped prior to trap development maui family oils do appear to be primarily sourced by rakopi formation late cretaceous coals in the northern part of the taranaki peninsula where heat flows are highest mangahewa kaimiro formation eocene coals are the chief sources of oils farther south in the kapuni and kupe south fields farewell formation paleocene coals appear to be the main oil source rocks biomarkers suggest that the onset of oil expulsion from coals occurs at a maturity level corresponding to a vitrinite reflectance of ca 0 8 ro and may be aided by the evolution of large volumes of carbon dioxide the terrestrial influence on paleogene source rocks diminishes to the north northwest of the basin and increasing marin contributions to oils are observed a late paleocene marine black shale is the source of oil in the kora volcanic structure it is possible that shales interbedded with coals reflecting periodic marine incursions of coastal flood plains also contribute to oil generation throughout much of the basin

identification of some bicyclic alkanes in petroleum abstract bicyclic alkanes containing the drimane skeleton have been identified in crude oils and sediments by synthesis of model compounds two other bicyclic alkanes whose skeletons do not conform to the isoprene rule have also been identified from mass spectral data a correlation between the relative concentration of c 29 steranes and diasteranes and drimane and two c 15 bicyclanes in an extensive sample suite suggests a similar mechanism is involved in the formation of diasteranes and the two c 15 bicyclanes in the subsurface the widespread occurrence of drimanes and drimane related compounds in crude oils and sediments indicates that these compounds are derived from a ubiquitous source the presence of methyldrimanes in a sample rich in methylhopanes suggests that drimanes and hopanes may be derived from similar precursors

significant changes in land vegetation and oceanic redox across the cretaceous paleogene boundary abstract the impact of an extraterrestrial body 65 5 ma caused the so called cretaceous paleogene k pg event that resulted in a mass extinction and rapid changes in the surface environment on earth here we report changes in land vegetation and oceanic redox across the k pg boundary at caravaca southeastern spain using biomarkers the results reveal that the basal 3 mm thick layer of the k pg boundary clay is marked by a rapid increase in the concentration of terrestrial long chain n alkanes and dibenzofuran indicating the destruction of land vegetation and an increase in the supply of terrestrial organic matter into the marine environment during the deposition of the k pg boundary clay this layer also records a rapid increase in the concentration of dibenzothiophenes which indicates a change in redox conditions from oxic to anoxic euxinic conditions in the intermediate water over the seafloor the low oxygen conditions could have been caused by an increase in the influx of terrestrial organic matter into the ocean a rapid increase in the concentration of retene and retene cadalene occurred during the deposition of the upper part of the boundary clay 10 kyr after the mass extinction indicating the recovery of conifers which greatly decreased at the k pg boundary

mo deposits in northwest china geology geochemistry geochronology and tectonic setting abstract northwest china covering northern xinjiang northern gansu and westernmost inner mongolia mainly includes junggar basin and its surrounding mountains such as chinese altay junggar chinese tianshan and beishan it lies at the junction of siberia tarim and kazakhstan plates and is a key sector of the central asian orogenic belt caob characterized by multistage phanerozoic continental growth herein at least nine mo only or mo dominated fourteen cu mo two w mo and one be mo deposits have been discovered these 27 deposits occur in altay west jungar west tianshan east tianshan and beishan areas and have been formed during accretionary or collisional orogenies the majority of the deposits are porphyry type followed by the skarn and quartz vein types the orebodies occur mainly as veins lens pods in the positions from inner intrusions through contact zones to the hostrocks distal to causative intrusions the host rocks are variable in lithologies including granites porphyries volcanic breccias and tuffs and sedimentary rocks outward from orebodies to hostrocks the wallrock alteration is zoning from potassic k feldspar quartz mica through phyllic quartz sericite chlorite epidote to propylitic or argillic alterations with skarn specifically occurring in skarn type systems hydrothermal mineralization generally includes four stages from early to late represented by 1 potassic feldspar quartz veins or veinlets 2 quartz molybdenite stockworks 3 quartz polymetallic sulfide stockworks and 4 quartz carbonate fluorite veins or veinlets the ore forming fluids were initially magmatic in origin and shew high temperature and high salinity containing daughter mineral and or co2 bearing fluid inclusions and eventually evolved to low temperature low pressure low salinity and co2 poor meteoric water the porphyry mo deposits can be further subdivided into two subtypes i e dabie and endako types the endako type mo deposits e g suyunhe and hongyuan together with all the cu mo systems were formed in the palaeozoic subduction related magmatic arcs the dabie type porphyry mo deposits represented by giant donggebi and baishan together with the mo only mo dominated and w mo or be mo deposits were formed in syn to post collisional tectonic setting with isotope ages ranging 260 213 2 ma with the kumutage skarn type mo system being an exception aged 319 ma the dabie type porphyry mo deposits are characterized by the co2 bearing fluid inclusions that cannot be observed in the endako type porphyry mo systems the re contents in molybdenites from porphyry and porphyry skarn cu mo systems are mainly 100 ppm suggesting a source significantly contributed by the mantle whereas the re contents in molybdenites from the mo only or w mo deposits are mainly

two contrasting late paleozoic magmatic episodes in the northwestern chinese tianshan belt nw china implication for tectonic transition from plate convergence to intra plate adjustment during accretionary orogenesis abstract late carboniferous to early permian is a critical period for the final amalgamation of the central asian orogenic belt caob however as most of the accreted terranes of the caob are unclear in tectonic nature and origin the timing and processes of their mutual amalgamation have been poorly constrained to understand assembly of the west junggar terrane with the yili block a suite of the late paleozoic magmatic rocks including ignimbrite rhyolite and granite in northwestern chinese tianshan belt were studied for their petrogenesis and tectonic implications our new results of secondary ion mass spectrometry sims zircon u pb dating reveal two separate magmatic episodes ca 300 ma volcanism ignimbrite and rhyolite and ca 288 ma plutonsim biotite granite geochemically for the ca 300 ma volcanism the ignimbrites have low sio2 65 8 71 5 wt and mg 6 13 values and exhibit arc affinity with significantly enriched in large ion lithophile elements lile and depleted in high field strength elements hfse such as nb ta and ti the whole rock end t and zircon ehf t values range from 6 9 to 7 0 and 9 9 to 14 1 respectively indicating a juvenile basaltic lower crustal origin rhyolites have slightly high sio2 72 7 74 0 wt and k2o 3 86 4 53 wt contents high zircon 18o 11 67 13 23 values and low whole rock end t 2 9 to 3 8 and zircon ehf t 2 8 to 10 0 values which may suggest sediment involvements during magma generation in contrast for the ca 288 ma plutonism the biotite granites have obviously higher sio2 74 7 75 5 wt contents and whole rock end t 7 7 to 8 8 zircon ehf t 9 8 to 12 7 and lower zircon 18o 5 99 6 84 values than those of the ca 300 ma volcanic rocks which are consistent with signatures of juvenile magma source according to our estimates of zircon saturation temperatures together with their contrasting genesis we attribute the formation of ca 300 ma high temperature 815 938 c volcanism to oceanic slab break off during assembly of the west junggar terrane with the yili block and relate the generation of ca 288 ma low temperature 723 735 c plutonism to subsequent strike slipping of north tianshan fault that facilitated introduction of water fluxes triggering hydrous partial melting of juvenile lower crust the sequential magmatic episodes in the northwestern chinese tianshan belt may provide a crucial clue to a tectonic transition from plate convergence to intra plate adjustment during the formation of the kazakhstan orocline in the late paleozoic

the adakite connection of the tuwu yandong copper porphyry belt eastern tianshan nw china trace element and sr nd pb isotope geochemistry the tuwu yandong porphyry copper belt lies in the eastern tianshan mountains eastern section of the central asian orogenic belt the copper mineralization is mainly hosted in plagiogranite porphyries intruded into early carboniferous volcanic rocks of the paleozoic dananhu island arc between the tarim and siberian plates the plagiogranite porphyries have contents of 65 73 wt sio2 14 17 wt al2o3 0 9 2 2 wt mgo 3 16 ppm y 0 4 1 40 ppm yb 347 920 ppm sr and positive eu anomalies the rocks also exhibit positive nd t values 5 0 to 9 4 and low initial 87sr 86sr values 0 70316 0 70378 such features are similar to those of adakites derived from partial melting of a subduction related oceanic slab the mineralization age is early carboniferous 350 320 ma which is close to that of the porphyries the close relationship between the cu mineralization and the porphyry is also indicated by their similar sr nd pb isotopic compositions we suggest that the copper porphyry magma system in the dananhu island arc was formed by direct melting of an obliquely subducting early carboniferous oceanic slab

fossil wood in middle upper jurassic marine sedimentary cycles of france relations with climate sea level dynamics and carbonate platform environments abstract vegetation climate and sea level oscillations interact in complex ways intuition suggests that climatic variations are recorded in geological deposits by both fossil phytoclasts and sediments therefore investigation of palaeobotanical remains within a precise sedimentological framework may help to decipher this much debated interaction a database of 129 jurassic bathonian oxfordian fossil wood samples from france is used here as a case study the palaeoenvironment freshwater swamp carbonate lagoon shoreface argillaceous offshore and the second order relative sea level phases were determined for each datum there is no correlation between the wood genera distribution and second order relative sea level cycles however 66 of the fossil wood samples were found within transgressive parts of cycles or at maximum flooding surfaces versus 34 in their regressive counterparts by contrast there is a close correlation between wood distribution and palaeoenvironment for agathoxylon and brachyoxylon the two most common genera although both genera occur in the four main depositional systems agathoxylon is the more common in offshore facies whereas brachyoxylon predominates in protected lagoon environments a model of wood deposition preservation is proposed it is shown that 1 the distribution of wood is not controlled by climate but by environmental processes related to relative sea level changes 2 the abundance of wood in transgressive deposits may be related to ravinement of previously emerged areas and or to the high preservational potential associated with increased accommodation space 3 carbonate platforms were probably inhabited by low diversity brachyoxylon xylofloras whereas offshore environments received a more diversified probably multi source flora from emergent land areas periods of bathonian callovian and oxfordian subaerial exposure of carbonate platforms may not have been conducive to the establishment of a diverse stable climax xyloflora

fluid fluid interactions in magmatic hydrothermal ore formation hydrothermal ore deposits have provided some of the first geological evidence for the interaction of multiple fluids in the earth s interior including fluid mixing as well as fluid phase separation physical evidence comes from veins and breccias documenting the impact of fluids in breaking rocks and creating fracture permeability for ore formation as a result of the fluid expansion that is commonly associated with phase separation between melts and multiple fluids chemical evidence of fluid fluid interaction includes the precipitation of minerals in veins as a result of fluid boiling or mixing between chemically contrasting fluids fluid inclusions record interactions of multiple fluids especially in magmatic hydrothermal ore deposits and associated igneous rocks fig 1 in recent years fluid inclusions have contributed to a more quantitative understanding of the role of fluid fluid interactions since new microanalytical techniques allow determination of element concentrations in all types of fluids from low density vapor through aqueous and hypersaline liquids to hydrous salt melts roedder 1984 samson et al 2003 figure 1 geological evidence for fluid phase separation in ore forming magmatic hydrothermal systems a bonanza grade gold 1 wt that was precipitated together with fine grained pyrite in a fluidized breccia resulting from instantaneous boiling and expansion of magmatic fluids ascending from an underlying andesite porphyry intrusion the breccia consists of adularia sericite altered clasts of sedimentary wall rock s and nodules of originally colloidal pyrite with bright specks of gold p g both cemented by roscoelite r vanadium rich muscovite and late calcite c zone vii ore body porgera papua new guinea ronacher et al 2004 b bladed manganocalcite the characteristic habit of calcite precipitated from aqueous epithermal fluids as a result of the ph change following loss of co2 to a separating vapor phase madan bulgaria kostova et al 2004 c growth band in a euhedral quartz

geochemical and geochronological studies of granitoid rocks from the western tianshan orogen implications for continental growth in the southwestern central asian orogenic belt abstract the western tianshan orogen in northwestern china is part of the southwestern margin of the central asian orogenic belt caob which represents the largest tectonic assembly of accretionary complexes and the most significant area of phanerozoic continental growth in the world granitoid rocks have a widespread occurrence and occupy about 30 of the whole exposure of the orogen ages obtained for the granitoids vary from 896 ma to 247 ma while initial 87 sr 86 sr ratios vary from 0 70329 to 0 72070 and e nd values from 14 1 to 7 3 the occurrence of neoproterozoic granitic gneisses implies the presence of precambrian basement in this area during oceanic subduction continental growth occurred as a result of several combined processes i e by addition of oceanic crustal melts adakites the intrusion of basaltic magmas derived by partial melting of the metasomatized depleted mantle wedge and the upwelling of granitic magma derived from a mixed source of basaltic magmas and old continental basement however during the post collisional period vertical accretion of underplated juvenile mantle material may have been accomplished during slab breakoff delamination this study suggests a two stage model of continental growth of syn subduction lateral accretion of arc complexes and post collisional vertical accretion of underplated mantle material which may also be relevant for the western segment of the caob in the phanerozoic the reworking and involvement of old crust are more obvious in the western tianshan orogen compared to other parts of the caob comprising the western junggar eastern junggar alataw and altay terranes

cyclic terpenoids of contemporary resinous plant detritus and of fossil woods ambers and coals abstract cyclic terpenoids present in the solvent extractable material of fossil woods ambers and brown coals have been analyzed the sample series chosen consisted of wood remains preserved in holocene to jurassic sediments and a set of of ambers from the philippines copalite israel canada and dominican republic the brown coals selected were from the fortuna garsdorf mine and miocene formations on fiji the fossil wood extracts contained dominant diterpenoid or sesquiterpenoid skeletons and aromatized species were present at high concentrations with a major amount of two ring aromatic compounds tricyclic diterpenoids were the predominant compounds in the ambers aromatized derivatives were the major components consisting of one or two aromatic ring species with the abietane and occasionally pimarane skeletons the saturated structures were comprised primarily of the abietane and pimarane skeletons having from three to five carbon c1 c2 etc substituents kaurane and phyllocladane isomers were present in only minor amounts bicyclic sesquiterpenoids as saturated and partial or fully aromatized forms were also common in these samples but only traces of sesterterpenoids and triterpenoid derivatives were found the brown coal extracts were composed of major amounts of one and two ring aromatized terpenoids with a greater proportion of triterpenoid derivatives than in the case of the woods and ambers this was especially noticeable for the german coal where the triterpenoids were predominant open c ring aromatized structures were also present in this coal steroid compounds were not detectable but some hopanes were found as minor components in the german brown coal an overview of the skeletal structure classes identified in each sample as well as the general mass spectrometric characteristics of the unknown compounds are included in the present paper it can be concluded from these structural distributions that aromatization is the main process for the transformation of terrestrial cyclic terpenoids during diagenesis constituting a general pathway for all terpenoids

aliphatic and aromatic terpenoid biomarkers in cretaceous and paleogene angiosperm fossils from japan abstract the distributions of aliphatic and aromatic terpenoids in cretaceous and paleogene angiosperm fossils from japan were investigated aliphatic a ring degraded oleanane ursane and lupane were found in all samples in addition aliphatic gymnosperm derived diterpenoids were detected in significant quantities aromatic oleanane type triterpenoids were the major components with ursane and lupane type triterpenoids being minor compounds in all angiosperm fossils in a cretaceous gymnosperm fossil major components included aliphatic labdane isopimarane and abietane type diterpenoids aromatic abietane type diterpenoids and chrysene and picene type polyaromatic hydrocarbons pahs trace amounts of oleanane ursane and lupane type triterpenoids were also identified it is likely that the aromatic triterpenoids were introduced to the gymnosperm fossil from the angiosperm derived material in the sediments we defined an angiosperm gymnosperm index al agi as an alternative to the aliphatic triterpenoid diterpenoid ratio proposed in the literature the al agi index may underestimate the angiosperm contribution because the aliphatic angiosperm derived triterpenoids are more readily converted to aromatic counterparts than the diterpenoids during diagenesis an aromatic angiosperm gymnosperm index ar agi can be calculated using aromatic diterpenoids and triterpenoids we suggest that ar agi is best calculated using only the oleanane ursane and lupane type aromatic triterpenoids and that the chrysene and picene type pahs be excluded

higher plant biomarkers reflect palaeovegetation changes during jurassic times abstract the relative abundances of three higher plant derived biomarkers retene cadalene and ip ihmn have been measured in marine sedimentary rocks from the northwest margin of australia it is thought that each biomarker represents input from a different plant type the distributions of these three compounds form a fingerprint representing higher plant input hpf variations in hpf in oxfordian sediments were nearly identical in all three locations with retene becoming very abundant relative to the other two compounds with decreasing age of the sediment this finding strongly suggests that the composition of terrestrial input during deposition largely determines hpf and that the possible effects of diagenesis and catagenesis on the distribution of the three biomarkers are relatively unimportant the marked increase in the abundance of retene relative to that of cadalene during the oxfordian is interpreted to reflect an increase in the contribution of plants that produced precursors for retene i e conifers brought about by a significant change in climate this was exemplified by measuring the distributions of retene and cadalene expressed in the higher plant parameter hpp for a suite of sediments from the carnarvon basin western australia covering the complete jurassic period the hpp profile displays three major cycles each covering a period of at least 10 million years this profile not only compared well with published palaeoclimate data but also showed a remarkable similarity with second order cycles in the global sea level curve thus strongly supporting the proposal that variations in hpf and hpp are indications of changes in palaeoclimate the relation with global sea level further suggests that global factors e g the atmospheric carbon dioxide concentration may play a major role in determining the observed variations in the distributions of these higher plant derived biomarkers

stump horizon in the bilina mine most basin czech republic gc ms optical and electron microscopy in identification of wood biological origin article i nfo numerous coalified tree stumps remained preserved in situ in the so called stump horizon the palaeontologic horizon no 31 which represents clayey overburden of themain coal seam in the bilina open cast mine in the most basin czech republic the petrological and chemical composition palaeobotanical origin and preservation of 24 selected tree stumps were studied by optical and scanning electron microscopy and gas chromatography mass spectrometry gc ms composition of the fossil wood is dominated by ulminite particularly texto ulminite b textinite forms up to 38 vol in the decomposed tree stumps corpohuminite dominates in bark and root tissues partly gelified and deformed woody tissuescontain both corpohuminite and resinite fillings randomreflectance of ulminite ranges from 0 33 to 0 39 and carbon content from 49 wt to 78 wt samples represent pure woody material with small admixtures of clay minerals siderite and very rare pyrite observations by scanning electron microscopy revealed various levels of deformed secondary xylem with more or less swollen cell walls conspicuous tracheids uniseriate rays of a different height and round or cylinder like resin or corpohuminite bodies according to our results and other published data the wood might belong to glyptostroboxylon and taxodioxylon genera that are supposed to belong to glyptostrobus and quasisequoia plants respectively representatives of the coniferous family cupressaceae the biomarker composition in the extracts of the fossil wood includes sesquiterpenoids cedrane drimane eudesmane diterpenoids abietane fichtelite 16 h phyllocladane and their degraded compounds the terpenoids are derived from precursors produced by the source plants and microorganisms the terpenoid signatures support a relationship to the cupressaceae family with input of microbial species these characteristics were identical for all studied samples significant variations have been observed in sesquiterpenoid cedrane and diterpenoid 16 h phyllocladane contents

an extended episode of early mesoproterozoic metamorphic fluid flow in the reynolds range central australia the products of metamorphic fluid flow are preserved in zones within the marbles and metamorphosed semipelites of the upper calcsilicate unit in the granulite portion of the late palaeoproterozoic reynolds range group northern arunta block central australia the zones of retrogression characterized by minerals such as wollastonite grossular and clinohumite local resetting of oxygen isotopic compositions and local major element metasomatism were channelways for water rich fluids derived from granulite facies metapelites u th pb isotopic ages measured by the shrimp ion microprobe on zircon and monazite from a granulite facies semipelite an early semiconcordant aluminous quartz rich fluid flow segregation and a late discordant quartz rich segregation record some of the extended thermal history of the area zircon cores from the semipelite show its likely protolith to be an igneous rock 1812 11 ma old itself derived from a source containing zircon as old as 2 2 ga low th u overgrowths on the zircon grew during granulite facies metamorphism at 1594 6 ma monazite cooled to its blocking temperature at 1576 8 ma zircon cores from the semiconcordant segregation are dominantly 2 3 ga old indicating that the source of the fluids was not the particular metamorphosed semipelite studied two generations of low th u overgrowths on the zircon give indistinguishable ages for the older and younger of 1589 8 and 1582 8 ma respectively the monazite age is the same 1576 12 ma zircon from the late discordant segregation gave 1568 4 ma fluid flow occurred for at least 18 3 ma and ended 26 3 ma after the peak of metamorphism suggesting a very slow cooling rate of 3 c ma 1 the last regional high grade metamorphism in the reynolds range occurred at 1 6 ga not 1 78 ga as previously thought the high grade event at 1 78 ga is a separate event that affected only the basement to the reynolds range group

vascular plant biomarkers as proxies for palaeoflora and palaeoclimatic changes at the dogger malm transition of the paris basin france abstract vascular plant biomarkers are used here as a chemostratigraphic tool for tracing both palaeoflora and palaeoclimatic changes during the callovian and oxfordian in the paris basin the retene cadalene ratio shows low values in claystones from the middle callovian to the end of the lower oxfordian then increases drastically from the end of the lower oxfordian cordatum zone synchronously with the progressive development of the oxfordian carbonate platform the relative proportion of retene a conifer biomarker is strongly correlated with the abundance of some of its diagenetic precursors and with saturated diterpanes some of these are very common and abundant in the pinaceae family while specific markers for non pinaceae conifers are not detected thus the increase in the retene cadalene ratio around the cordatum zone reflects the rising proportion of pinaceae on the london brabant massif which was the nearest land from the locations studied as pinaceae show many morphological adaptations to dry climate compared to the other plants reported in the jurassic taphofloras of the paris basin their increasing proportion indicates an increasing aridity this climatic change is also supported by published geochemical palaeobiogeographical palynological palaeobotanical and mineralogical data a comparable increase in the relative proportion of retene was also described for the oxfordian of western australia which could be an argument for a worldwide increase in aridity at the end of the lower oxfordian

fluid inclusion and vitrinite reflectance geothermometry compared to heat flow models of maximum paleotemperature next to dikes western onshore gippsland basin australia abstract nine basalt dikes ranging from 6 cm to 40 m thick intruding the upper jurassic lower cretaceous strzelecki group western onshore gippsland basin were used to study maximum temperatures t max reached next to dikes t max was estimated from fluid inclusion and vitrinite reflectance geothermometry and compared to temperatures calculated using heat flow models of contact metamorphism thermal history reconstruction suggests that at the time of dike intrusion the host rock was at a temperature of 100 135 c fracture bound fluid inclusions in the host rocks next to thin dikes t max systematically increases towards the dike margin to at least 500 c the estimated t max next to the thickest dike thickness d 40 m suggests an extended zone of elevated r v r to at least a distance from the dike contact x of 60 m or at x d 1 5 using a normalized distance ratio used for comparing measurements between dikes regardless of their thickness in contrast the pattern seen next to the thin dikes is a relatively narrow zone of elevated r v r heat flow modeling along with whole rock elemental and isotopic data suggests that the extended zone of elevated r v r is caused by a convection cell with local recharge of the hydrothermal fluids the narrow zone of elevated r v r found next to thin dikes is attributed to the rise of the less dense heated fluids at the dike contact causing a flow of cooler groundwater towards the dike and thereby limiting its heating effects the lack of extended heating effects suggests that next to thin dikes an incipient convection system may form in which the heated fluid starts to travel upward along the dike but cooling occurs before a complete convection cell can form close to the dike contact at x d r v r often decreases even though fluid inclusion evidence indicates that t max is still increasing further fluid inclusion evidence indicates that the evolution of water vapor or supercritical fluids in the rock pores corresponds to the zone where r v r begins to decrease the generation of the water vapor or supercritical fluids near the dike contact seems to change vitrinite evolution reactions these metamorphic conditions closer to the dike than x d 0 3 make vitrinite reflectance unreliable as a geothermometer the form of the r v r profile as it indicates t max can be interpreted using temperature profiles estimated from various heat flow models to infer whether the dike cooled by conduction incipient convection or a convection cell a contact aureole that consists of decreasing r v r or t max extending out to x d 2 and that has a t contact t magma t host 2 appears to be a signature of simple conductive cooling incipient convection is indicated by a r v r profile that decreases to background levels at x d r v r profile and consistently high r v r that may not decrease to background levels until beyond distances of x d 1 5

microgranular enclaves in island arc andesites a possible link between known epithermal au and potential porphyry cu au deposits in the tulasu ore cluster western tianshan xinjiang china abstract the successful exploration for porphyry copper deposit in western tianshan xinjiang faces great challenge tulasu basin is an important epithermal gold ore cluster in western tianshan which was formed in a southwest pacific type island arc setting during the late paleozoic by the southward subduction of the north tianshan ocean beneath the yili plate porphyry cu au deposits are possibly to be found at depth or adjacent to these epithermal gold deposits some sulfide mineralized microgranular enclaves of monzonite porphyry and microdiorite were found in andesites of the tawuerbieke gold district tulasu basin the enclaves are randomly distributed with generally round or subangular shape and commonly clearly defined within their host andesite and have a chilled surrounding margin of andesite the monzonite porphyry enclaves mpe exhibit porphyritic texture with the phenocrysts of plagioclase and k feldspar the microdiorite enclaves mde are mainly composed of plagioclase and hornblende with an aplitic texture and massive structure the host andesites show porphyritic texture with the phenocrysts major of plagioclase minor of hornblende and clinopyroxene the groundmass consists of short column plagioclase and minor clinopyroxene with a hyalopilitic texture zircon grains from a mpe sample yield a weighted 206pb 238u age of 356 2 4 3 ma n 13 mswd 1 11 which is effectively coincident with the 360 5 3 4 ma n 20 mswd 0 61 of an andesite sample within analytical error indicating that they were coeval in addition the mpe mde and the andesite samples share similar normalized incompatible element and rare earth element patterns that are characterized by a pronounced enrichment of large ion lithophile elements and a deficit of high field strength elements moreover the samples show similar nd isotope compositions to the contemporary andesites and basaltic andesites detailed petrology geochronology and geochemistry studies suggest that these enclaves were captured from an underlying body during the eruption of island arc magma thus unmapped cognate porphyry intrusions associated with cu au mineralization may exist under the andesite strata this evidence in combination with the low and high sulfidation epithermal gold deposits acidic hydrothermal alterations and copper mineralization evidence suggests that a porphyry epithermal cu au metallogenic system might occur in the tulasu basin of western tianshan and that the tawuerbieke district should be an important target for porphyry cu au exploration

triterpanes and ring a degraded triterpanes as biomarkers characteristic of tertiary oils derived from predominantly higher plant sources abstract a number of oils previously proposed to be derived from terrigenous source materials have been obtained from the taranaki basin new zealand niger delta beaufort mackenzie region taiwan and indonesia and their c24 tetracyclic and c30 pentacyclic terpenoid distributions examined by gc ms and gc ms ms the c24 tetracyclic terpanes are thought to be derived from their corresponding c30 hopane oleanane ursane and lupane counterparts as previously reported a mixture of at least nine c30 pentacyclic terpanes are found to be present with remarkably uniform distributions in oils from these widely separated provinces whilst definitive structures have not been proposed for these compounds information has been obtained as to whether these pentacyclic terpanes are all six membered rings or contain one or two five membered rings the presence of this mixture of tetracyclic and pentacyclic terpanes provides a good indicator for oils derived from terrigenous source materials and in the case of these basins of tertiary age

chemostratigraphy of the posidonia black shale sw germany ii assessment of extent and persistence of photic zone anoxia using aryl isoprenoid distributions aquatic depositional environments where anoxic conditions extend from bottom waters into the photic zone occurred frequently during the geologic past periods of photic zone anoxia pza can be recognized by the presence of specific lipids produced exclusively by the green sulphur bacteria chlorobiaceae that are preserved in the sedimentary record chlorobiaceae perform anoxygenic photosynthesis that requires light penetration into h2s saturated waters sediment samples integrate paleoenvironmental conditions over time intervals ranging from at best a few decades to more commonly several millennia photic zone anoxia recognized in paleoenvironmental analyses is thus defined as episodic with no further interpretation on the duration and persistence of the anoxic events we provide here a high resolution multiproxy chemostratigraphy study for the toarcian posidonia black shale from the dotternhausen section in sw germany in order to assess duration and seasonal fluctuation of photic zone anoxia based on the relative abundance of derivatives of chlorobiaceae lipids we assess the variability in the degree and persistence of photic zone anoxia using an aryl isoprenoid ratio air obtained by calculating the proportion of the short chain c13 17 versus the intermediate chain c18 22 aryl isoprenoids higher relative abundance of the short chain analogues is interpreted as indicating more intensive aerobic degradation of aryl isoprenoids air varies between values of 0 5 indicative of persistent pza phases and 3 0 for short termed episodic pza events absolute concentration of aryl isoprenoids is negatively correlated with the air which is in agreement with a progressive diagenetic breakdown of aryl isoprenoids the air decreases are validated using independent palecological and geochemical redox indicators for the posidonia shale in sw germany d 2004 elsevier b v all rights reserved

biomarker signatures of upper cretaceous latrobe group hydrocarbon source rocks gippsland basin australia distribution and palaeoenvironment significance of aliphatic hydrocarbons abstract upper cretaceous maastrichtian and campanian hydrocarbon source rocks from the latrobe group gippsland basin australia have been analysed using gas chromatography mass spectrometry gc ms in order to understand their geochemical characteristics and to reconstruct palaeovegetation and palaeoclimate changes n alkanes ranging from c10 to c37 dominate the aliphatic hydrocarbons in the rock extracts both the carbon preference index and the odd to even predominance values of n alkanes are higher than 1 0 suggesting an input from terrigenous higher plants low wax indices mostly 3 0 a low gammacerane index

early cretaceous adakitic granites in the northern dabie complex central china implications for partial melting and delamination of thickened lower crust abstract to date few adakitic rocks have been reported in direct association with contemporary intra continental extensional structures which has cast doubt on genetic models involving partial melting of the lower crust this study presents early cretaceous 143 129 ma new sensitive high resolution ion microprobe shrimp zircon u pb ages adakitic granites which are directly associated with a contemporary metamorphic core complex i e the northern dabie complex in the dabie area these granites exhibit relatively high sr contents negligible to positive eu and sr anomalies high la yb and sr y ratios but very low yb and y contents similar to subducted oceanic crust derived adakites they are also characterized however by very low mgo or mg and ni values and nd sr isotope compositions end t 14 6 to 19 4 and 87sr 86sr i 0 7067 0 7087 similar to triassic continent derived eclogites subducted in the dabie sulu orogen additionally late granitic dikes in the adakitic intrusions exhibit low sr contents clearly negative eu and sr anomalies low la yb and sr y ratios but relatively high yb and y contents similar to 118 105 ma granites in the northern dabie complex based on composition and geochronology data of neoproterozoic amphibolites and orthogneisses triassic high to ultra high pressure metamorphic rocks and early cretaceous mafic ultramafic intrusive rocks and the constraints provided by experimental melt data for tonalites metabasaltic rocks and eclogites we suggest that the adakitic granites were most probably generated by partial melting of thickened amphibole or rutile bearing eclogitic lower crust as a consequence of triassic middle jurassic subduction and thrusting the late dikes probably originated from plagioclase bearing intermediate granulites moreover we suggest that late mesozoic delamination or foundering of thickened eclogitic lower crust is also a more plausible mechanism for the petrogenesis of early cretaceous mafic ultramafic intrusive rocks in the dabie area and probably involved partial melting of a mixed source comprising eclogitic lower crust that had delaminated or foundered into upper lithospheric or asthenospheric mantle peridotite asthenospheric upwelling in response to post collisional delamination of lithospheric mantle was likely to have provided the heat source for the cretaceous magmatism

alteration and mineralization at the zhibula cu skarn deposit gangdese belt tibet abstract the zhibula cu skarn deposit contains 0 32 mt cu metal with an average grade of 1 64 and is located in the gangdese porphyry copper belt in southern tibet the deposit is a typical metasomatic skarn that is related to the interaction of magmatic hydrothermal fluids and calcareous host rock stratiform skarn orebodies occur at the contact between tuff and marble in the lower jurassic yeba formation alteration zones generally grade from a fresh tuff to a garnet bearing tuff a garnet pyroxene skarn and finally to a wollastonite marble minor endoskarn alteration zonations are also observed in the causative intrusion which grade from a fresh granodiorite to a weakly chlorite altered granodiorite a green diopside bearing granodiorite and to a dark red brown garnet bearing granodiorite prograde minerals which were identified by electron probe microanalysis include andradite grossularite of various colors e g red green and yellow and green diopside retrograde metamorphic minerals overprint the prograde skarn and are mainly composed of epidote quartz and chlorite the ore minerals consist of chalcopyrite and bornite followed by magnetite molybdenite pyrite pyrrhotite galena and sphalerite three types of fluid inclusions are recognized in the zhibula deposit including liquid rich two phase inclusions type l vapor rich two phase inclusions type v and daughter mineral bearing three phase inclusions type s as the skarn formation evolved from prograde stage i to early retrograde stage ii and later retrograde stage iii the ore forming fluids correspondingly evolved from high temperature 405 667 c high salinity up to 44 0 wt nacl equiv and high pressure 500 600 bar to low moderate temperature 194 420 c moderate high salinity 10 1 18 3 and 30 0 44 2 wt nacl equiv and low moderate pressure 250 350 bar isotopic data of 34 s 0 1 to 6 8 estimated 34 s fluids 0 7 d h2o 91 to 159 and 18 o h2o 1 5 to 9 2 suggest that the ore forming fluid and material came from magmatic hydrothermal fluids that were associated with miocene zhibula intrusions fluid immiscibility likely occurred at the stage i and stage ii during the formation of the skarn and mineralization fluid boiling occurred during the stage iii which is the most important cu deposition mechanism for the zhibula deposit

ore genesis and hydrothermal evolution of the kendenggao er copper molybdenum deposit western tianshan evidence from isotopes s pb h o and fluid inclusions abstract the boluokenu range is one of the most important metallogenic belts in northwest china and it contains numerous fe cu mo au etc deposits the kendenggao er cu mo deposit is located in the eastern segment of the boluokenu metallogenic belt within the western tianshan orogeny skarn and cu mo orebodies occur as lamellae or lenses along the contacts between different units of the upper carboniferous dongtujinhe formation and the aimujin granitic intrusions based on field investigations and petrographic observations three main metallogenic stages of skarn formation and ore deposition have been distinguished 1 the pre ore stage is characterized by the formation of garnet wollastonite and diopside and high temperature hypersaline hydrothermal fluids with oxygen isotopic compositions that are similar to those of magmatic fluids these fluids were most likely generated by the separation of brine from the silicate melt due to the immiscibility of primary magmatic fluids that occurred at a depth of approximately 1 km with inferred lithostatic pressure conditions of 300 bars 2 the main ore stage coincides with the replacement of garnet and diopside by vesuvianite epidote sulfides and quartz the hydrothermal fluids of this stage are represented by v type vapor rich fluid inclusions that coexist with l type liquid rich inclusions the oxygen isotope 18oh2o values of the main ore stages are in a narrow range of 7 5 9 9 which indicates that the mineralization related fluid is also of magmatic origin based on the fluid inclusion and stable isotopic data it can be concluded that the ore forming fluid evolved by the boiling of the magmatic fluids that likely occurred at a depth of 1 km and hydrostatic pressure of 100 bars and that this was the predominant mechanism for the large scale precipitation in the kendenggao er cu mo deposit 3 the post ore stage is characterized by the development of calcite quartz and chlorite the fluids during this stage are represented by the l type inclusions which mainly show low salinity and low homogenization temperatures these fluids yield the lowest 18oh2o values 2 8 to 3 7 the above data indicate that the post ore stage fluids originated from the mixing of residual main ore stage fluids with various proportions of external water low salinity low temperature no boiling occurred at this stage at the low temperatures the 34s values of the sulfides range from 4 3 to 1 9 and the 206pb 204pb 207pb 204pb and 208pb 204pb values of the sulfides range from 18 220 to 18 554 15 608 to 15 812 and 38 080 to 39 055 respectively the s and pb isotopic compositions indicate that the ore materials were mainly derived from magmas taken together these geologic geochemical and isotopic data confirm that kendenggao er is a typical skarn deposit

organic geochemistry of the lower miocene oberdorf lignite styrian basin austria its relation to petrography palynology and the palaeoenvironment abstract in the oberdorf trough at the northwestern margin of the styrian basin austria an up to 36 m thick lower miocene ottnangian lignite seam occurs within the fluvial koflach voitsberg formation previous results indicate that the lignite originated in a topogenous mire within a wet forest swamp palaeoenvironment differences in soluble organic matter som yield of borehole samples from the lignite seam are related to free lipids present in plant waxes or resins and the presence of thermally labile polymers indicated by the contents of liptinite macerals i e resinite suberinite and liptodetrinite the n alkane distribution patterns are dominated by high molecular weight lipids with marked odd over even predominance originating from plant waxes a contribution of algae to the even numbered short chain lipids observed in considerable amounts in the footwall sediments is proposed terpenoid biomarkers characteristic for conifers and angiosperms were detected consistent with palynomorphic spectra which are dominated by forest swamp pollen taxodiaceae cupressaceae and pollen from plants living in a mixed mesophytic forest excellent relationships between higher plant biomarker composition and palynologic data indicate that the organic geochemical results reflect the varying inputs of coniferales vs angiosperms the data further imply that cuparene may be used for taxonomical differentiation of coniferales families organic geochemical data provide evidence that the content of land plant derived biomarkers is controlled by the input of resin rich conifers concentrations of hopanoids dominated by hop 17 21 ene generally increase towards the top of the lignite a section characterised by high extents of aromatisation of triterpenoid biomarkers the results suggest that the aromatisation of angiosperm derived biomarkers may be governed by the activity of anaerobic rather than by aerobic bacteria however changes in the depositional environment and palynologic facies during peat formation probably influenced the origin and fate of angiosperm derived triterpenoids the results indicate how biomarker composition may contribute to the evaluation of environmental changes cross correlations of organic geochemical parameters with palynological data and petrography based facies indicators will provide further insights in the peat forming vegetation and biogeochemical activities in the mire

biomarkers of holocene buried conifer logs from bella coola and north vancouver british columbia canada abstract the biomarker compositions of a holocene seep oil liquefied resin originating from a buried log of douglas fir pseudotsuga menziesii from bella coola bc canada and a holocene pine wood pinus sp sample from north vancouver bc canada were analyzed using gas chromatography mass spectrometry gc ms the total extract of the bella coola sample contains the sesquiterpenoid derivative calamenene and diterpenoids of the labdane abietane pimarane and phyllocladane classes a novel series of successively degraded labdane derivatives labdan 15 oic acid norlabdanoic acids drimenoic acid was detected in the polar fraction and a diagenetic pathway is proposed aromatic abietanes are the major components in the neutral fraction the neutral fraction of the pine wood contains two sesquiterpenoids calamenene cadalene diterpenoids of the abietane pimarane isopimarane and kaurane classes and a series of steroids 18 norabieta 8 11 13 triene dehydroabietin is the major component among the predominantly aromatic abietanes based on the compositions of the terpenoids it is concluded that the diagenesis of the pine and douglas fir logs probably occurred under anaerobic conditions leading to reductive reactions such as decarboxylation of resin acids with concurrent oxidation reactions to form the aromatic derivatives

site characterisation of a basin scale co2 geological storage system gippsland basin southeast australia geological storage of co2 in the offshore gippsland basin australia is being investigated by the cooperative research centre for greenhouse gas technologies co2crc as a possible method for storing the very large volumes of co2 emissions from the nearby latrobe valley area a storage capacity of about 50 million tonnes of co2 per annum for a 40 year injection period is required which will necessitate several individual storage sites to be used both sequentially and simultaneously but timed such that existing hydrocarbon assets will not be compromised detailed characterisation focussed on the kingfish field area as the first site to be potentially used in the anticipation that this oil field will be depleted within the period 2015 2025 the potential injection targets are the interbedded sandstones of the paleocene eocene upper latrobe group regionally sealed by the lakes entrance formation the research identified several features to the offshore gippsland basin that make it particularly favourable for co2 storage these include a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping and dissolution non reactive reservoir units that have high injectivity a thin suitably reactive lower permeability marginal reservoir just below the regional seal providing mineral trapping several depleted oil fields that provide storage capacity coupled with a transient production induced flow regime that enhances containment and long migration pathways beneath a competent regional seal this study has shown that the gippsland basin has sufficient capacity to store very large volumes of co2 it may provide a solution to the problem of substantially reducing greenhouse gas emissions from future coal developments in the latrobe valley

occurrence of polycadinene in fossil and recent resins abstract dammars produced by dipterocarpaceae growing in southeast asia are partly composed of a macromolecule with a polycadinene structure this polymer is the precursor of many specific compounds encountered in crude oils and sediment extracts from south asia until recently there was no evidence for a more widespread geographical occurrence of this resinous polymer using different pyrolysis methods it is shown that the polymers present in a resinite from utah usa and in resins contained in resin canals of eocene fossil fruits from germany and england are also polycadinenes the fossil fruits were undoubtedly produced by ancient representatives of mastixioid cornaceae a group of plants which was widespread in the tertiary of europe and north america and which is not related to dipterocarpaceae these findings extend the known occurrence and origin of the sesquiterpenoid type resin polymer it is to be expected that catagenetic products of these resin polymers should be present in oils coals and sediment extracts from areas outside southeast asia

palynology petrography and geochemistry of the sewickley coal bed monongahela group late pennsylvanian northern appalachian basin usa abstract forty two bench samples of the sewickley coal bed were collected from seven localities in the northern appalachian basin and analyzed palynologically petrographically and geochemically the sewickley coal bed occurs in the middle of the pittsburgh formation monongahela group and is of late pennsylvanian age palynologically it is dominated by spores of tree ferns tree fern spore taxa in the sewickley include punctatisporites minutus punctatosporites minutus laevigatosporites minimus spinosporites exiguus apiculatasporites saetiger and thymospora spp in fact punctatisporites minutus was so abundant that it had to be removed from the standard counts and recorded separately average 73 2 even when punctatisporites minutus is removed from the counts tree fern spores still dominate a majority of the assemblages averaging 64 4 among the tree fern spores identified in the sewickley coal thymospora exhibits temporal and spatial abundance variation thymospora usually increases in abundance from the base to the top of the bed thymospora is also more abundant in columns that are thick 100 cm and low in ash yield calamospora spp laevigatosporites minor and l vulgaris are the next most abundant plant group represented in the sewickley coal averaging 20 contributions from all other plant groups are minor in comparison petrographically the sewickley coal contains high percentages of vitrinite average 82 3 mineral matter free mmf with structured forms being more common than unstructured forms in contrast liptinite and inertinite macerals both occur in low percentages average 7 7 and 10 0 respectively geochemically the sewickley coal has a moderate ash yield average 12 4 and high total sulfur content average 3 4 four localities contained a high ash or carbonaceous shale bench these benches which may be coeval are strongly dominated by tree fern spores unlike the lower ash benches they contain low percentages of vitrinite which mainly occurs as unstructured vitrinite and higher liptinite and inertinite contents the accumulated data suggest that the sewickley paleomire was probably a rheotrophic planar mire that had a consistent water cover this is supported by the high vitrinite contents moderate ash yields and high total sulfur contents the high ash and carbonaceous shale benches probably represent either periods of dryness and substrate exposure or flooding of the mire surface the duration of which is unknown

biomarker signatures of upper cretaceous latrobe group petroleum source rocks gippsland basin australia distribution and geological significance of aromatic hydrocarbons abstract aromatic hydrocarbons extracted from upper cretaceous maastrichtian and campanian latrobe group coaly shales and shales from the gippsland basin were investigated by gas chromatography mass spectrometry a variety of 2 ring to 6 ring aromatic hydrocarbons were identified including both higher plant derived and combustion derived polycyclic aromatic hydrocarbons pahs these aromatic compounds indicate that the upper cretaceous coaly shales and shales were deposited in a fluvial deltaic environment with significant higher plant input and are at a relatively low thermal maturity stage higher plant parameters and angiosperm gymnosperm indices based on aromatic components suggest that higher land plants including both angiosperms and gymnosperms were an important part of the palaeovegetation in the upper cretaceous the aromatic angiosperm gymnosperm index that includes chrysene and picene type pahs is not as reliable for evaluation of relative angiosperm and gymnosperm contributions as the aliphatic indices due to input of combustion derived pahs and the complexity of burning conditions altering the relative contributions however combustion derived pahs and aromatic angiosperm gymnosperm indices supplement the information from aliphatic hydrocarbons and provide further evidence to support the hypothesis that palaeoclimate cooled from the campanian to the maastrichtian

age geochemistry and tectonic implications of a late paleozoic stitching pluton in the north tian shan suture zone western china the central asian orogenic belt is the largest tectonic assembly of continental and oceanic terranes on earth due to closure of the paleo asian ocean in the phanerozoic among major suture zones in the north xinjiang region of western china the north tian shan suture zone because of collision between the yili terrane in the south and the junggar terrane in the north contains the youngest ophiolitic rocks and may represent the terminal stage of development of the central asian orogenic belt in western china but the timing of the suture zone remains poorly constrained a sensitive high resolution ion microprobe shrimp zircon u pb age of 316 3 ma i e the beginning of the late carboniferous from the undeformed sikeshu pluton which crosscuts the suture zone places a crucial upperage bound for the time of collision between the yili and junggar terranes this event occurred later than or nearly concurrent with other accretion collision events in the north xinjiang region implying that fi nal terrane amalgamation was completed in the late carboniferous the sikeshu pluton shares geochemical characteristics of the widespread late carboniferous to permian postcollisional a type and i type granitoids with depleted mantle like sr nd isotopic signatures in the north xinjiang region they all occurred during a protracted ca 320 270 ma episode of postcollisional magmatism that may have been induced by basaltic under plating due to either slab breakoff or delamination of thickened mantle lithosphere beneath the central asian orogenic belt the same postcollisional magmatism also generated cu ni sulfi de bearing mafi c ultramafi c magmatic complexes adakites and porphyry type coppermolybdenum bearing magmatic rocks in the north xinjiang region

from a mountain belt collapse to a sedimentary basin development 2 d thermal model based on inversion of stratigraphic data in the paris basin abstract the thermal mineralogical and mechanical behaviour of the lithosphere determines the genesis and evolution of sedimentary basins subsidence amplitude geometry of sediment bodies sedimentary processes using the large stratigraphic database available for the paris basin we constrain the lithosphere thermal evolution thickness and rigidity as well as the mechanism that gave birth to this wide intracontinental basin the thermal subsidence calculated with a two dimensional thermal model is adjusted to the estimated tectonic subsidence by optimization of three parameters extension profile crustal thickness profile and average mantle heat flow the best fits for the paris basin lithosphere are obtained for a mantle heat flow of 23 mw m 2 and for an elastic thickness lower than 20 km preferred value te 5 km two mechanisms for the origin of the basin subsidence have been tested a pure extensional collapse of the variscan belt and a delamination of the mantle lithosphere at the end of carboniferous it appears that in both cases inverted extension factors are large in the range 1 2 1 85 in the first case and in the range 1 0 1 85 in the second case both cases involve the presence of a thick variscan crustal wedge and a mountain belt elevation of 1500 3500 m located in the paris basin centre the maximum extensional rates are obtained in the centre part of the basin in addition lithospheric delamination at around 300 ma allows for both crustal and mantle melting in agreement with the widespread existence of permian bimodal magmatism in france at the end of extension the basin centre kept a high elevation of about 1000 m before subsiding around 40 my later below sea level

paleozoic tectonic evolution of the tianshan orogen northwestern china abstract the chinese tianshan orogenic belt which extends west east for about 1500 km is one of the most important paleozoic orogenic belts in central asia it includes parts of the tarim yili central tianshan and junggar plates which are microcontinental blocks with precambrian basements and meso cenozoic depositional covers the tarim plate is separated from the yili central tianshan plate by the southern central tianshan suture early carboniferous ophiolitic melanges and blueschists are widespread in this suture and are believed to be produced by the collision between a passive continental margin on the north side of the tarim plate and an active continental margin on the south side of the yili central tianshan plate the collision occurred at the end of early carboniferous the yili central tianshan and the junggar plates are separated by the northern central tianshan suture also considered as an early carboniferous collisional zone along which the middle ordovician ophiolitic melanges blueschists and late devonian early carboniferous ophiolites are exposed in early paleozoic times the subduction of the paleo junggar ocean took place in an active margin on the north side of the yili central tianshan plate along the northern central tianshan suture at the end of early carboniferous the north side of the yili central tianshan plate collided with the north tianshan arc along this suture the paleo oceanic crust in the tianshan and adjacent region was entirely consumed at the end of early carboniferous meanwhile the tarim yili central tianshan and junggar plates were accreted to eurasia epicontinental sediments were then deposited throughout the tianshan region during the middle late carboniferous times in the early permian tianshan began to uplift with accompanying volcanic eruption and granitic intrusion the uplift was accelerated in the late permian and continental molasse was extensively deposited

contrasted distributions of triterpene derivatives in the sediments of lake caco reflect paleoenvironmental changes during the last 20 000 yrs in ne brazil lipid fractions extracted from sediment layers deposited in a small brazilian lake during the last 20 000 yrs were investigated by gas chromatography mass spectrometry considerable differences in the distribution and the amount of triterpene derivatives in the aliphatic as well as in the aromatic fractions were observed all along the series although no precise identification of these compounds was undertaken our interpretation of mass spectral data allowed us to discriminate between des a triterpenes mono and triaromatic derivatives of pentacyclic triterpenes and a series of compounds tentatively identified as diaromatic derivatives of tetracyclic triterpenes the largest compound diversity was found in the lowest levels of the series dated back to the end of the last glacial maximum when good preservation of terrestrial plant debris was ensured by rapid burial in a semi arid climate then except for a period corresponding to the younger dryas only des a lupane was detected in significant amounts the high predominance of des a lupane is interpreted to result from the development of a belt of eleocharis sp spike rush that filtered most of organic inputs from the catchment and was the site of des a lupane production and exportation towards the lake centre during the younger dryas a strong influx of des a lupane is attributed to the destruction of the spike rush belt consecutive to the lowering of the lake level under drier conditions the temporary destruction of this barrier allowed other triterpene derivatives to reach the lake the distinct dynamics of des a and aromatic triterpene derivatives under variable medium conditions led us to hypothesis that these two families of compounds derive from distinct pools that contributed differently to the sediment depending on environmental and climatic conditions des a lupane was most probably produced in sub aquatic conditions within the belt of spike rush conversely aromatic derivatives of triterpenes could have resulted from the degradation of their biological precursors within reducing micro environments in the catchment

paleozoic accretion and cenozoic redeformation of the chinese tien shan range central asia the tien shan range in central asia contains two late paleozoic sutures the older southern suture marks the collision of a passive margin at the north of the tarim block and an active continental margin subduction under the latter was to the north the younger northern suture separates a northern carboniferous island arc from an active continental margin developed over a south dipping subduction zone the subduction direction under the island arc is unknown mesozoic elastics were deposited over the doubly sutured orogen rate and energy of sedimentation waned until deposition of oligocene conglomerates above a regional unconformity interpreted as marking the onset of deformation induced by the india asia collision molasse deposition accelerated in pliocene and quaternary time and deposition continues today as active thrusts generate relief paleozoic structures control the gross divergence of cenozoic thrusts across the orogen

influence of floral assemblage facies and diagenesis on petrography and organic geochemistry of the eocene bourgas coal and the miocene maritza east lignite bulgaria abstract numerous differences in the petrography and organic geochemistry of two tertiary low rank coal deposits of bulgaria formed within comparable depositional environments are outlined different floral assemblages are indicated as the main sources of organic matter for the eocene bourgas sub bituminous coals a warm climate plant community dominated by angiosperms is reflected in the biomarker composition whereas a coniferous flora was the main source of the resinous organic matter of the miocene maritza east lignite the results are in agreement with palaeobotanical data these differences in the peat forming vegetation of the paleogene compared to the neogene of bulgaria are attributed to decreasing temperature during the tertiary the abundance of resinous compounds relative to lipids from plant waxes long chain n alkanes as well as the preservation of plant tissue are mainly controlled by gymnosperm angiosperm ratios pristane phytane and diasterenes sterenes ratios reflect variations in redox conditions and the ph of the depositional environments caused by eustatic sea level changes freshwater inflow or varying ground water table changing eh and ph values are associated with differences in microbial activity controlling the extent of gelification of plant tissue bacteria most probably contributed to the aromatisation of triterpenoids in the mire enhanced thermal maturation of organic matter during diagenesis is reflected in higher contents of n alkanes and the presence of alkyl naphthalenes in the bourgas coals alkyl naphthalenes are thought to have been formed from pentacyclic triterpenoids rather than from resinous compounds

application of new diterpane biomarkers to source biodegradation and mixing effects on central llanos basin oils colombia llanos basin oils have been commonly attributed to the prolific upper cretaceous age source formations outcropping in the eastern cordillera recently however variable oleanane indices have been reported for llanos oils suggesting a contribution from tertiary source sequences largely on the basis of the presence of high relative abundance of oleanane a tertiary age diagnostic biomarker a homologous series of 25 norhopanes in many central llanos basin oils indicates that heavy biodegradation is particularly common to the initial oil charging reservoirs from upper cretaceous marine sources one homologue 20s 25 norhomohopane c30 25 norhopane co elutes with oleanane and may thus contribute to the peak attributed to oleanane also confusing the source identification is the possibility that some cretaceous facies also contain oleanane three plant diterpanes which may be isomers of fichtelite and are common to the central llanos oils have been observed in an eocene source rock sample but not in cretaceous rocks or oils providing additional strong evidence for a tertiary contribution to some llanos basin oils in mixed oils with low to moderate oleanane contents and with a strong co eluting c30 25 norhopane the fichtelite isomers are the more reliable indicators of tertiary source input