campanian bolivinoides and microfacies from the la luna formation western venezuela abstract tres esquinas the upper member of the la luna formation a 1 3 m thick condensed sequence composed of glauconitic phosphorite signals the commencement of the late cretaceous regression in western venezuela this is the last of a series of thin phosphatic beds the others non glauconitic occurring in the upper la luna formation in the state of merida the presence of bolivinoides culverensis restricts these phosphatic beds to the late santonian early campanian with the tres esquinas member assigned to the globotruncanita elevata globotruncana ventricosa zones bolivinoides sp cf b sirticus is also commonly found in these beds although no bolivinoides have been detected in the tres esquinas member in the state of tachira to the west the non glauconitic phosphate bed informally named capa ii as well as the 15 m thick ftanita de tachira member which underlies the tres esquinas member and separates it from capa ii contain bolivinoides culverensis as well as bolivinoides cf b sirticus this occurrence combined with the assignation of the base of the overlying colon formation to the globotrucana aegyptiaca zone suggests a late campanian age for the member in this area and implies that the member is diachronous on the basis of lithology mineralogy foraminiferal content and degree of bioturbation six microfacies and one sub microfacies are identified the microfacies of the phosphatic limestones containing bolivinoides spp are notably different in the two states

plate tectonic paleoceanographic hypothesis for cretaceous source rocks and cherts of northern south america new paleocontinental reconstructions show a northern migration of the south american plate with respect to the paleoequator from the jurassic to the late cretaceous this movement caused the northern margin of south america to migrate from a position south to a position north of the paleoequator ekman transport generated net surface water movement towards the south during times when northern south america was south of the paleoequator this situation favored downwelling and prevented jurassic and earliest cretaceous marine source rocks from being deposited when northern south america was north of the paleoequator ekman transport forced net water movement to the north favoring upwelling paleoproductivity and the deposition of one of the best marine source rocks known the la luna villeta and equivalents this plate tectonic paleoceanographic hypothesis explains the origin of hydrocarbons in northern south america the stratigraphic record reflects this increase in paleoproductivity through time this can be observed in facies non calcareous shales to calcareous shales to siliceous shales and finally to bedded cherts and in changing planktic communities which were initially dominated by healthy calcareous foraminifer assemblages followed by stressed foraminifer populations and finally by radiolarians total organic carbon and source rock quality were affected by this longmore term increase in paleoproductivity but also and more markedly by a punctuated sequence stratigraphic record dominated by low frequency changes in relative sea level the magnitude of transgressive episodes caused by rise in sea level determined the extent of source rock intervals and indirectly the content of organic carbon less

a hypothesis for the origin of perylene based on its low abundance in sediments of green bay wisconsin abstract perylene a polycyclic aromatic hydrocarbon pah that is common in sediments is believed to originate principally from anaerobic diagenesis of organic matter but its precursor material remains enigmatic we have investigated the formation of perylene in a dated sediment core from green bay wi comparisons of sedimentary profiles of perylene anthropogenic pahs land plant derived hydrocarbons and aquatic contributions of organic matter rule out a specific industrial terrigenous or aquatic precursor for perylene instead perylene seems to be formed from any kind of organic matter as a consequence of a specific type of microbial activity in sub bottom sediments despite an abundance of organic matter the amount of perylene is low in green bay and in other organic carbon rich lake sediments the abundant availability of organic matter that stimulates microbial activity in green bay sediments would seem to favor perylene formation in such sediments we therefore hypothesize that the microorganisms responsible for perylene formation do not compete successfully with those that flourish in sediments rich in organic matter perylene formation consequently does not become significant until deeper in sediments after the more reactive types of organic matter have been consumed

paleoenvironmental changes during the late albian oceanic anoxic event 1d an example from the capacho formation southwestern venezuela abstract the late albian early cenomanian oceanic anoxic event 1d oae 1d 103 to 99 5 ma represents a global interval of enhanced organic carbon burial due to widespread oxygen deficiency in the water column and or increased primary productivity the biostratigraphy and geochemistry of organic rich sediments in the la grita member capacho formation in southwestern venezuela were studied to document the paleoenvironmental conditions that governed the deposition of this succession during oae 1d carbon isotope 13ccarb and 13ccorg chemostratigraphy and biostratigraphic constraints show that the la grita member spans the late aptian period rotalipora appenninica zone and that oae 1d is well recorded in this succession a prominent increase in total organic carbon toc values up to 10 is clearly recorded through the onset of oae 1d coinciding with a prominent change in overall redox sensitive proxies suggesting that the la grita member sediments accumulated under anoxic and possibly euxinic bottom water conditions in a partially restricted basin the detrital proxies suggest that the greenhouse climate prevailing during oae 1d induced significant acceleration of the hydrologic cycle and an increase in continental chemical weathering rates overall the carbon and oxygen isotope records toc contents as well as the detrital proxies show cyclic variation during the late albian stage these variations support the hypothesis that orbital forcing likely also modulated the equatorial monsoonal activity during the oae 1d

complete archive of late turonian to early campanian sedimentary deposition in newly drilled cores from the tarfaya basin sw morocco an expanded succession of organic rich marlstones and limestones deposited in the tarfaya basin provides an outstanding opportunity to closely retrace climate evolution and sea level changes during the cretaceous greenhouse period we present high resolution x ray fluorescence xrf scanning and bulk carbon and oxygen isotope records from two newly drilled sediment cores in the tarfaya atlantic coastal basin which recovered a continuous upper turonian to campanian succession of 290 m thickness the xrf core scanning records reveal three long term oscillations in the abundance of terrigenous elements increase of al ti k si and fe normalized against ca which correspond to progressive transgressive phases followed by rapid regressions during the coniacian and early santonian sea level highstands during this interval corresponding to the coniacian santonian oceanic anoxic event 3 oae 3 are characterized by overall oxygen depleted to anoxic conditions at the seafloor indicated by the high organic carbon content the presence of laminations and low log mn s high log v ca and high log br ca the upper santonian interval marks the transition from anoxic to oxic bottom water conditions prevalent through the early campanian the composite bulk carbonate 13 c curve exhibits strong similarities to the global stacked 13 c reference curve characterized by negative excursions in the early coniacian navigation and east cliff events and late santonian bracketed by the haven brow and buckle events and by positive excursions in the latest turonian hitchwood event middle coniacian wight fall event and at the santonian campanian boundary during the early campanian enhanced accumulation of fine grained carbonate and clay rich hemipelagic sediments increasing bulk carbonate 18 o and low log br ca and log v ca values indicate climate cooling associated with a substantial improvement in bottom water ventilation two long term 13 c cycles of 2 m y duration probably related to variations in earth s orbital eccentricity are associated with the long term cooling trend initiating the campanian maastrichtian climate transition toward a cool greenhouse state

a record of long and short term environmental and climatic change during oae3 la luna formation late cretaceous santonian early campanian venezuela abstract the la luna formation was deposited under anoxic dysoxic conditions in a tropical epicontinental sea on the northwest south america margin sedimentological micropaleontological and geochemical evidence provides insights into factors that influenced the sedimentation and controlled the accumulation of organic rich deposits at decimeter and meter scales during the youngest of the cretaceous oceanic anoxic events oae the la luna formation consists of an alternation of black marlstones interbedded with black limestones and black marly limestones the benthic foraminifera assemblages indicate sedimentation in the upper neritic to upper bathyal environment these rocks contain large amounts of organic matter it is interpreted that a combination of warm global and rainy climate and the presence of bathymetric barriers caused poor circulation and low rates of water column ventilation during a high sea level in the early santonian leading to the preservation of carbon rich deposits in this region during the late santonian a cooling trend in global climate increased wind strength and upwelling this change probably reduced runoff causing a weakening of the pycnocline and destabilized the stratification in the water column providing a progressive increase in oxygen in the water column and on the sea floor and a decrease in total organic carbon preservation in a shallower basin these changes and the establishment of full mid and deep water exchange in response to the deepening and widening of the equatorial atlantic gateway could have been important mechanisms for ending the epeiric sea anoxia changes through time in the vanadium nickel fraction planktonic and benthic foraminifera assemblages productivity proxy elements and lithological characteristics support this model superimposed on the general trend variations in calcium carbonate and total organic carbon percentages at the scale of tens of centimeters reveal high frequency cyclic variations which apparently correspond to the main frequencies of orbital forcing this cyclicity is interpreted as a primary depositional signal and is the result of orbital controlled fluctuations in terrigenous dilution and variations in oxygen concentration at the base of the water column variations in the intensity of upwelling can be observed but they did not control the cyclicity

late cretaceous dysoxia in a southern high latitude siliciclastic succession the otway basin southeastern australia the warm greenhouse world of the late cretaceous created oceans that were poorly stratified latitudinally and vertically periodically these oceans experienced globally significant events where oxygen minimum zones enveloped the continental margins evidence of the effect of one of these ocean anoxic events oaes is preserved in the southern high latitude strata of the offshore otway basin in southeast australia during the late cretaceous thick successions up to 6 km of mudstonedominated deltaic to upper bathyal sediments the otway delta were deposited in an elongate inlet ca 500 km wide between antarctica and australia located at least 708 s the initial turonian strata of this succession the waarre formation were deposited in upper delta plain to delta front conditions the overlying late turonian flaxman formation and basal belfast mudstone formation preserve evidence of transgressive lower delta plain to prodelta conditions at inner to middle shelf depths these units were subject to periodic dysoxia during deposition caused by intermittent freshwater input and deepening seas resulting in periods of thermohaline stratification and reduced bottom waters rapid subsidence from 89 3 ma to 85 7 ma created significant accommodation space leading to the seaward progradation of normal marine prodelta to upper bathyal mudstone dominated facies at middle shelf to upper slope depths after a period when the oxygen minimum zone contracted near the base of the coniacian upward increasing dysoxia in the belfast mudstone formation heralds the onset of coniacian to santonian dysoxic conditions this event in the otway basin correlates to oae 3 the last ocean anoxic event of the warm cretaceous before the onset of cooler conditions in the uppermost cretaceous the evidence suggests that rather than confined to low latitude tropical areas the effects of oae 3 reached southern high latitude regions during the warm late cretaceous the cessation of growth faulting after 85 7 ma reduced accommodation space and delta front to prodelta facies prograded rapidly seaward hyposaline conditions and higher sedimentation rates due to delta front progradation and shallowing during this time

new oxygen isotope evidence for long term cretaceous climatic change in the southern hemisphere a new composite 18 o record generated from calcareous fine fraction and bulk sediments from the exmouth plateau details long term cretaceous climatic change at mid latitudes in the southern hemisphere assessment of new and previously published 18 o data indicates that a mid cretaceous global climatic optimum was achieved sometime between the time of the cenomanian turonian boundary and the middle turonian when surface ocean paleotemperatures were the highest of the past 115 m y periods of cooling and warming that reversed the general patterns were superimposed on long term aptian turonian warming and turonian maastrichtian cooling trends respectively extrapolation of southern hemisphere paleotemperature trends to maastrichtian paleotemperature data from a low latitude pacific guyot implies that maximum mid cretaceous low latitude paleotemperatures could have been in excess of 33 c

geochemical signatures of bedded cherts of the upper la luna formation in tachira state western venezuela assessing material provenance and paleodepositional setting abstract here we undertook an inorganic geochemical study of cenomanian campanian bedded cherts the tachira ftanita member of the la luna formation in the western region of the tachira state venezuela the aim of this study was to determine the paleo oceanographic and paleo environmental conditions that governed the deposition of chert beds and put forward a sedimentation model for the tachira ftanita member in the study area seventy two chert samples were collected and trace rare earth elements la ce pr nd sm eu gd tb dy ho er tm yb lu rb cs th u y co and sc and major trace elements sio2 tio2 al2o3 fe2o3 mgo cao na2o k2o p2o5 mn ba sr cr ni and v were determined by icp ms and icp oes respectively on the basis of the stratigraphic abundance and distribution of relatively immobile elements as well as the distribution of rare earth elements we established that the detrital sediments associated with the sequences studied have matching characteristics with distinct continental materials with an intermediate composition thus pointing to the guayana massif as the main source of sediments in addition we also determined the influence of hydrothermal input on the chemical composition of some cherts from la molina mine on the basis of geochemistry we found a biological influence regarding the uptake of dissolved silica for forming chert beds the application of parameters for relatively immobile elements allowed us to establish a still proximal continental margin hemipelagic for most samples from the zorca river and a continental margin for almost all the cherts from the delicias villa paez section and the remaining samples from la molina mine finally we propose that the rhythmicity that accompanies the sequence of bedded cherts is related to changes in the intensity of upwelling patterns of water and or to variability in the supply of silica dissolved in the tachira sub basin

a 200 year sedimentary record of progressive eutrophication in lake greifen switzerland implications for the origin of organic carbon rich sediments over the past 200 years lake greifen a small lake in northeastern switzerland has undergone dramatic changes in primary productivity and eutrophication due to increased nutrient supply from agricultural activity and industrialization a 40 year historical record of the water column chemistry indicates that productivity and eutrophication reached a maximum in 1974 after which stricter regulations on the input of nutrients resulted in a progressive decrease collected cores show the sedimentary expression of this anthropogenically induced eutrophication by a well developed annual sedimentation and by enhanced values of total organic carbon organic carbon accumulation rates and hydrogen indices hi of the kerogens analyses of the carbon isotopic composition of sedimentary carbonates and organic matter reveal that the fractionation between these two phases varies with the hi of kerogens this observation is explicable in terms of changing productivity and preservation of the organic matter and the co2 aq budget of the water body we propose that if high primary productivity were primarily responsible for the preservation and accumulation of organic matter then a negative correlation will occur between 13ccalcite organic matter 13ccal om and hi values in an environment with relatively low to moderate productivity but with bottom water anoxia a positive correlation will exist between 13ccal om and hi values this study of lake greifen has implications for understanding paleoenvironmental controls on ancient organic carbon rich sediments

basin modeling of late cretaceous mio pliocene petroleum system of the deep water eastern colombian basin and south caribbean deformed belt abstract previous interpretation of 2d and 3d seismic reflection data have shown widespread direct hydrocarbon indicators from deep water successions of the eastern colombian basin ecb and adjacent south caribbean deformed belt scdb that suggest the presence of an extensive but poorly defined petroleum system we integrate rock eval analysis seismic interpretation and 1d 2d thermal and basin modeling to better understand the origin of gas chimneys and bright spots identified in the ecb our dataset consists of 36 rock eval samples of coniacian to santonian source rocks from the dsdp well sites 153 151 and 146 located in the beata ridge tied to a 270 km long composite 2d seismic line covering the ecb rock eval analyses reveal intervals of immature source rocks containing 1 kerogen types ii and iii 2 an average toc of 3 17 with a maximum toc of 11 4 3 an average hi of 241 and 4 an average oi of 124 seismic interpretation reveals 1 wedging of post coniacian organic rich successions from the beata ridge 35 73 m towards the ecb 500 1700 m 2 late cretaceous to eocene slow sedimentation rate of 38 m my followed by faster oligocene to recent sedimentation rate of 149 m my from the magdalena river and 3 late oligocene to recent thrusting and propagation of the scdb thermal and basin modeling show 1 mature source rocks in the scdb and ecb 2 miocene to pliocene reservoir and seal rocks related to deltaic and turbiditic sandstone and mass transport deposits of the magdalena fan 3 trap formation since the late oligocene related to thrust front structures compaction folds and stratigraphic traps 4 hydrocarbon expulsion since pliocene times 5 vertical and lateral migration in the scdb and vertical up dip migration in the ecb and 6 hydrocarbon accumulation and preservation may be affected by remobilization due to biodegradation and trap breaching

correction of the sea state impact in the l band brightness temperature by means of delay doppler maps of global navigation satellite signals reflected over the sea surface this paper presents an efficient procedure based on 2 d convolutions to obtain delay doppler maps ddms of global navigation satellite signals reflected gnss r over the sea surface and collected by a spaceborne receiver two ddm derived observables area and volume are proposed to link the sea state induced brightness temperature to the measured normalized ddm finally the requirements to use global positioning system reflectometry to accurately correct for the sea state impact on the l band brightness temperature quantization levels decimation truncation and noise impact are analyzed in view of its implementation in the passive advanced unit instrument of the spanish earth observation satellite seosat ingenio project

late cretaceous to early quaternary organic sedimentation in the eastern equatorial atlantic abstract reconstructing the long term evolution of organic sedimentation in the eastern equatorial atlantic odp leg 159 provides information about the history of the climate ocean system sediment accumulation and deposition of hydrocarbon prone rocks the recovery of a continuous 1200 m long sequence at odp site 959 covering sediments from albian to the present day about 120 ma makes this position a key location to study these aspects in a tropical oceanic setting new high resolution carbon and pyrolysis records identify three main periods of enhanced organic carbon accumulation in the eastern tropical atlantic i e the late cretaceous the eocene oligocene and the pliocene pleistocene formation of upper cretaceous black shales off west africa was closely related to the tectono sedimentary evolution of the semi isolated deep ivorian basin north of the cote d ivoire ghana transform margin their deposition was confined to certain intervals of the last two cretaceous anoxic events the early turonian oae2 and the coniacian santonian oae3 organic geochemical characteristics of laminated coniacian santonian shales reveal peak organic carbon concentrations of up to 17 and kerogen type i ii organic matter which qualify them as excellent hydrocarbon source rocks similar to those reported from other marginal and deep sea basins a middle to late eocene high productivity period occurred off equatorial west africa porcellanites deposited during that interval show enhanced total organic carbon toc accumulation and a good hydrocarbon potential associated with oil prone kerogen deposition of these toc rich beds was likely related to a reversal in the deep water circulation in the adjacent sierra leone basin accordingly outflow of old deep waters of southern ocean origin from the sierra leone basin into the northern gulf of guinea favored upwelling of nutrient enriched waters and simultaneously enhanced the preservation potential of sedimentary organic matter along the west african continental margin a pronounced cyclicity in the carbon record of oligocene lower miocene diatomite chalk interbeds indicates orbital forcing of paleoceanographic conditions in the eastern equatorial atlantic since the oligocene miocene transition a similar control may date back to the early oligocene but has to be confirmed by further studies latest miocene early pliocene organic carbon deposition was closely linked to the evolution of the african trade winds continental upwelling in the eastern equatorial atlantic ocean chemistry and eustatic sea level fluctuations reduction in carbonate carbon preservation associated with enhanced carbon dissolution is recorded in the uppermost miocene 5 82 5 2 ma section and suggests that the latest miocene carbon record of site 959 documents the influence of corrosive deep waters which formed in response to the messinian salinity crisis furthermore sea level related displacement of higher productive areas towards the west african shelf edge is indicated at 5 65 5 6 5 55 5 2 4 8 ma in view of humid conditions in tropical africa and a strong west african monsoonal system around the miocene pliocene transition the onset of pronounced toc cycles at about 5 6 ma marks the first establishment of upwelling cycles in the northern gulf of guinea an amplification in organic carbon deposition at 3 3 ma and 2 45 ma links organic sedimentation in the tropical eastern equatorial atlantic to the main steps of northern hemisphere glaciation and testifies to the late pliocene transition from humid to arid conditions in central and western african climate aridification of central africa around 2 8 ma is not clearly recorded at site 959 however decreased and highly fluctuating carbonate carbon concentrations are observed from 2 85 ma on that may relate to enhanced terrigenous eolian dilution from africa

retrieval of significant wave height and mean sea surface level using the gnss r interference pattern technique results from a three month field campaign since 1993 when the european space agency esa proposed the use of global navigation satellite systems reflected signals for sea mesoscale altimetry a wide range of applications have appeared this paper focuses on the retrieval of significant wave height swh and the mean sea surface level mssl from a ground based experiment using the interference pattern technique ipt two different observables on the ipt are analyzed the oscillation frequency and the angle where coherency is lost the point where coherency in the reflection process is lost can be related to the rayleigh criterion for smooth surfaces and helps to determine the swh spectral analysis on the interference pattern helps to determine the mssl a three month field campaign was performed on the pont del petroli pier badalona spain to see how the reflected gnss signals were affected by coastal sea state and check previous assumptions results from this field experiment are shown confirming that the swh can be retrieved with accuracy of 6 cm and the mssl with 4 cm estimations of both parameters are obtained every 30 min approximately

middle late cretaceous climate of the southern high latitudes stable isotopic evidence for minimal equator to pole thermal gradients a detailed 18 o and 13 c stratigraphy has been generated from analysis of well preserved albian early maastrichtian foraminifera from deep sea drilling project dsdp sites 511 and 327 falkland plateau 58 s 62 s paleolatitude in the southern south atlantic and cenomanian and coniacian santonian foraminifera from dsdp site 258 naturaliste plateau 58 s paleolatitude in the southern indian ocean these results when combined with previously published maastrichtian stable isotope data from ocean drilling program odp site 690 weddell sea 65 s paleolatitude provide new insight into the climatic and oceanographic history of the southern high latitudes during middle late cretaceous time the planktonic foraminifer 18 o curves reveal a gradual warming of surface waters from the albian through the cenomanian followed by extremely warm surface waters from the turonian through the early campanian long term cooling of surface waters began in the late early campanian and continued through the end of the maastrichtian the benthic foraminifer 18 o record generally parallels changes in the oxygen isotopic curves defined by shallow dwelling planktonic foraminifera the vertical oxygen and carbon isotopic gradients were relatively low during the albian cenomanian high from the turonian early campanian and then low during the late campanian and maastrichtian foraminiferal oxygen isotopic data from published sources and this study are averaged for each site corrected for latitudinal changes in salinity based on modern day surface water values and plotted versus paleolatitude for the late albian coniacian santonian and late maastrichtian differences between lowand high latitude surface water paleotemperatures are estimated at 14 c during the late albian and late maastrichtian but the coniacian santonian reconstruction reveals only a 0 4 c latitudinal temperature gradient uncertainty regarding cretaceous salinity gradients and possible diagenetic alteration of 18 o values introduce error into our estimates of paleolatitudinal thermal gradients however apparent low equator to pole temperature differences could indicate much higher poleward heat transport than at present

relationship between inferred redox potential of the depositional environment and geochemistry of the upper pennsylvanian missourian stark shale member of the dennis limestone wabaunsee county kansas u s a analyses of 21 samples collected from a core of the 52 8 cm thick stark shale member of the dennis limestone in wabaunsee county kansas demonstrate four cycles with two orders of magnitude variations in contents of cd mo p v and zn and order of magnitude variations in contents of organic carbon cr ni se and u the observed variability in amounts and or ratios of many metals and amounts and compositions of the organic matter appear related to the cause and degree of water column stratification and the resulting absence presence of dissolved o2 or h2s high cd mo u v zn and s contents a high degree of pyritization dop 0 75 0 88 and high high v v ni 0 84 0 89 indicate the presence of h2s in a strongly stratified water column intermediate contents of metals and s intermediate dop 0 67 0 75 and intermediate v v ni 054 0 82 indicate a less strongly stratified anoxic water column whereas low metal contents and low v v ni 0 46 0 60 indicate a weakly stratified dysoxic water column high p contents at the top of the organic matter rich intervals within the stark shale member indicate that phosphate precipitation was enhanced near the boundary between anoxic and dysoxic water compositions relatively abundant terrestrial organic matter in intervals deposited from the more strongly stratified h2s bearing water column indicates a combined halocline thermocline with the fresher near surface water the transport mode for the terrestrial organic matter the predominance of algal organic matter in intervals deposited from a less strongly stratified water column indicates the absence of the halocline and the presence of the more generally established thermocline relatively low amounts of degraded hydrogen poor organic matter characterize intervals deposited in a weakly stratified dysoxic water column the inferred variability in chemistry of the depositional environments may be related to climate variations and or minor changes in sea level during the general phase of deeper water deposition responsible for this widespread shale member

millennial to centennial scale record of african climate variability and organic carbon accumulation in the coniacian santonian eastern tropical atlantic ocean drilling program site 959 off ivory coast and ghana millennial to centennial scale geochemical records of coniacian to santonian deposits from the deep ivorian basin are used to develop a model for the accumulation of black shales in equatorial regions during the final of the cretaceous oceanic anoxic events oae proxy records from ocean drilling program site 959 document a strong precessional signal in the occurrence of black shales the abundance of quartz and clay mineralogy during oae 3 we hypothesize that this signal reflects changes in atmospheric circulation patterns which in turn caused latitudinal shifts of continental climate belts across western africa furthermore we propose that the periodic deposition of black shales occurred in response to adjustments of oceanic circulation in the deep ivorian basin resulting from climate controlled fluctuations in continental runoff a new high resolution cyclostratigraphic framework allowed us to estimate a rapid change within 1000 yr from dysoxic background to anoxic or euxinic black shale environmental conditions followed by black shale deposition for 10 k y and a gradual return to the initial dysoxic conditions our findings imply a highly dynamic late cretaceous atmosphere ocean system

scavenged excess aluminum and its relationship to bulk titanium in biogenic sediment from the central equatorial pacific ocean we present results from chemical analyses of al and ti in surface sediment sampled along two cross equator latitudinal transects at 135w and 140w in the central equatorial pacific ocean although traditionally both al and ti are considered to reside exclusively within terrigenous phases in marine sediment these sediments present extremely high al ti ratios that are several times that of average shale and other potential crustal sources a sharp maximum in al ti is observed slightly south of the equator where sedimentary bulk accumulation rate bar is also highest reflecting elevated productivity in the overlying water caused by surface water divergence bulk al ti decreases sharply away 2 latitude to near crustal values at 4 north and south the latitudinal profiles of al ti are entirely unrelated to the concentration of the biogenic components as well as to the absolute accumulation of al and ti these results indicate the presence of a significant scavenged component of al sourced directly from seawater during particle settling the data from the two transects analytically and oceanographically confirms our earlier work that was based on the single 135w transect calculations of alexcess indicate that the highest al ti ratios correspond to 50 of the total al being unsupported by the small amount of terrigenous phases present these results are consistent with previous and ongoing studies of biogenic sediment suspended particulate matter and sediment trap material quantitative use of al as an index of terrigenous material may therefore lead to an overestimation by a factor of two of the true terrigenous load in marine sediment sedimentary rock and settling particles because bulk al ti appears to respond to sedimentary bar which in biogenic regimes is linked to surface water productivity downcore records of al ti in biogenic sediment may track productivity changes through time such al ti proxy records may be applicable in sediment of all ages unlike radionuclide tracers which are limited by radioactive decay to use over the past hundreds of kyr

chemical evidence of differential particle dispersal in the southern washington coastal environment aliphatic hydrocarbons cupric oxide oxidation products of lignin and polycyclic aromatic hydrocarbons pah were analyzed by capillary gas chromatography in sediments from the southern washington continental shelf and slope the concentration of diploptene relative to plantwax n alkanes increased systematically in surface sediments with distance offshore along east west transects of the study area and remained constant in surface sediments along the midshelf silt deposit analogous trends were also observed for the concentration of cinnamyl phenols relative to vanillyl phenols and total methylphenanthrenes relative to phenanthrene these changes in sedimentary composition are evidence that diploptene from some terrestrial source lignin characteristic of non woody vascular plant tissue and a fossil organic material contained within weathered rock debris disperse across the washington continental shelf and slope in geographic patterns distinct from that for other river derived chemically related materials the compositional variations are explained by the particulate associations of the land derived chemicals and differential hydraulic dispersion of their respective carrier particles after discharge at the mouth of the columbia river

from phytoplankton to oil shale reservoirs a 19 million year record of the late cretaceous tethyan upwelling regime in the levant basin abstract the complexity of sedimentary organic matter formation its source to burial and influence on bottom water communities are addressed in this study of the 19 million years long upper cretaceous tethyan upwelling regime in the levant a multi proxy approach is amalgamated into a model through which the paleoceanographic complexity of an intense and long lasting upwelling system is better understood a shift in primary producer assemblages and reorganization of the bottom water bacterial consortium followed the campanian maastrichtian boundary enforcing conspicuous sedimentological and faunal changes the siliceous and phosphatic bearing sediments of the campanian gave way to maastrichtian uniform and regionally distributed organic rich carbonates accompanied by an increase in sedimentation rates from 1 to 6 cm kyr this has facilitated both the increase in organic matter production and its excellent preservation and through diagenetic pathways affected its elemental composition these paleoceanographic modifications have also affected foraminiferal assemblages from massive blooms of triserial buliminid benthic foraminifera during the campanian which have sequestered diatom chloroplasts to diverse trochospiral forms during the maastrichtian using nitrate instead of oxygen for their respiratory pathways we propose that shifts in the type of primary producers promote a change in the amount and type of preserved organic matter in bottom water communities on the lithological composition of the rock mass and ultimately on the hydrocarbon generation potential of the studied source rock the continued rise of southern tethyan sea level and global highstands during the upper maastrichtian culminating into arabian plate wide maximum flooding surfaces cause the migration of upwelling activity away from the study area terminating the high productivity sequence in the levant

cretaceous black shales of venezuelan andes preliminary results on stratigraphy and paleoenvironmental interpretations abstract this paper deals mainly with the late cretaceous la luna formation on the venezuelan andean platform the studied area the so called transversale de barquisimeto is located at the contact zone between the andes of merida and allochthonous slabs thrusted from the caribbean domain and is crosscut by a major active transform fault the bocono fault which is part of the contact zone between the caribbean and south american plates the la luna formation is made of dark organic rich laminated limestones and shales and though always appearing with black shale facies is different in the areas located in the north or in the south of the bocono fault we provide here some new information about the biostratigraphic frame of the la luna formation and of the overlying colon formation in the studied area the depositional environment of the la luna formation was certainly rather shallow near storm wave base and stratified during deposition of la luna formation dysaerobic to anoxic conditions prevailed which may be linked with a regional anoxic event perhaps related to seasonal upwelling along the northern coast of south america during late cretaceous time

global and local controls influencing the deposition of the la luna formation cenomanian campanian western venezuela bulk and molecular geochemical micropalaeontological and carbon isotopic data are used to address the different local and global factors influencing the environment of sedimentation of the la luna formation cenomanian campanian approximate palaeolatitude 15 n in a single section in western venezuela based on the constructed chronostratigraphic framework oxygen depleted bottom water conditions and black shale deposition started in western venezuela well before the widespread occurrence of organic rich sediments in higher palaeolatitude regions such as the tethys and the north atlantic near or at the cenomanian turonian boundary in the la luna formation palaeoenvironmental conditions that allowed the preservation of organic matter mainly of marine origin prevailed until santonian times in a distal platform facies with very low siliciclastic input changes in lithology appear to reflect the local response to eustatic sea level variations and the presence of a migrating upwelling belt affecting the bioproductivity of silica and carbonate a marked 13corg isotopic excursion is recognised in the middle part of the section and is apparently unrelated to local palaeoenvironmental changes in bioproductivity and oxygen depletion biological marker data show no variations in association with the isotopic excursion being mainly controlled by local fluctuations in organic matter input and preservation

the cenomanian turonian oceanic anoxic event ii palaeoceanographic controls on organic matter production and preservation correlation of the 13c spike with the well dated occurrences of strata rich in organic carbon detailed in schlanger et al this volume indicates that a global episode of intense organic carbon orgc burial took place during the latest cenomanian earliest turonian oceanic anoxic event oae a plenus through i labiatus macrofossil zones and upper r cushmani trz through w archecretacea prz foraminiferal zones over a period of no more than 1 million years m y the shape of the 13c curve indicates that rates of orgc burial gradually increased in the early part of the late cenomanian increased more rapidly in the later cenomanian and levelled off at peak values in latest cenomanian early turonian time during the maximum rate of orgc burial the 13c values decreased nearly to pre late cenomanian levels in the early to middle turonian the decrease in 13c reflects decreasing rates of orgc burial following the cenomanian turonian oceanic anoxic event as well as the probable oxidation and return of significant amounts of orgc to the oceans following regression and re oxygenation of much of the deeper water masses in contact with the seafloor

palaeoecology palaeogeography and depositional environments of upper cretaceous rocks of western venezuela abstract the end of the early cretaceous in northern south america was marked by regional palaeoceanographic change in western venezuela this change was highlighted near the end of the albian by drowning of the maraca formation shallow water carbonate platform regional marine transgression continued during the cenomanian and turonian in western venezuela with drowning of the more southerly guayacan member capacho and escandalosa formations carbonate platform deposition of organic carbon rich intervals of the la luna and navay formations occurred unconformably on maraca formation and guayacan member shallow water carbonates and continued through the early santonian during this interval the maracaibo and barinas apure basins were characterized by low oxygen or anoxic bottom water conditions away from the basin margins deposition of organic carbon lean upper la luna and navay formation strata show that bottom water oxygen content increased from the late santonian through the end of the cretaceous the siliceous and phosphatic late santonian to early maastrichtian tres esquinas member and the glauconitic late campanian to early maastrichtian socuy member both of the la luna formation represent the final phase of la luna deposition in the maracaibo basin tectonic uplift in eastern colombia during the campanian and maastrichtian caused progradation of the colon mito juan and burguita formation deltas and eventual infilling of the maracaibo and barinas apure basins

analysis of marine environmental conditions based onmolybdenum uranium covariation applications to mesozoic paleoceanography article i nfo article history accepted 13 september 2011 available online 17 september 2011 patterns of uranium molybdenum covariation in marine sediments have the potential to provide insights re garding depositional conditions and processes in paleoceanographic systems specifically such patterns can be used to assess bottom water redox conditions the operation of metal oxyhydroxide particulate shuttles in the water column and the degree of water mass restriction the utility of this paleoenvironmental proxy is due to the differential geochemical behavior of u and mo 1 uptake of authigenic u by marine sediments begins at the fe ii fe iii redox boundary i e suboxic conditions whereas authigenic mo enrichment re quires the presence of h2s i e euxinic conditions and 2 transfer of aqueous mo to the sediment may be enhanced through particulate shuttles whereas aqueous u is unaffected by this process in the present study we examine u mo covariation in organic rich sediments deposited mostly in the western tethyan region during oceanic anoxic events oaes of early jurassic to late cretaceous age our analysis generally confirms existing interpretations of redox conditions in these formations but provides significant new insights regard ing water mass restriction and the operation of particulate shuttles in depositional systems these insights will help to address contentious issues pertaining to the character and origin of mesozoic oaes such as the degree to which regional paleoceanographic factors controlled the development of the oaes

orbitally induced limestone marlstone rhythms in the albian cenomanian cismon section venetian region northern italy sedimentology calcareous and siliceous plankton distribution elemental and isotope geochemistry abstract a multidisciplinary study of the upper albian cenomanian portion of the cismon section venetian region northern italy was undertaken in order to characterize the cyclic alternations of carbonate rich and carbonate poor layers and to investigate their possible origin and cyclic patterns limestone semicouplets are characterized by abundant radiolarians and micarbs micron sized calcitic fragments common planktonic foraminifera strong bioturbation good oxygenation as expressed by the mn and v v ni parameters high si al ratio low k al in the absence of pyrite and organic matter the marlstone semicouplets are on the contrary frequently laminated rich in pyrite and organic matter with common fish remains in the absence of radiolarians the mn and v v ni parameters indicate that the marlstone deposition occurred in dysoxic to anoxic conditions which allowed the preservation of organic matter the low si al ratio and high k al ratio the latter related to abundant feldspars indicate that marlstones received a substantial contribution from a terrigenous source the abundance of biogenic silica suggests that during limestone deposition surface waters were rather fertile due to an efficient recycling of nutrients from deeper waters the enhanced fertility was coupled with an efficient current system at the welloxygenated sea floor which prevented the organic matter from accumulating during marlstone deposition surface waters were less fertile than in the limestone semicouplets but still within the mesotrophic spectrum as indicated by the presence of fertility index species among calcareous nannofossils whereas the bottom waters were oxygen depleted to accommodate fertility at the surface with stagnation at the bottom the scenario implies an enhanced stratification caused by an increase in freshwater runoff monitored by 18o depleted values in the meantime the water discharge supplied the nutrients to the surface waters necessary for the calcareous nannofossils to proliferate the cyclic organization of limestone marlstone couplets as revealed by power spectral analysis seems to represent climatic cycles the alternating conditions are 1 efficient mixing highly fertile surface and near surface waters and a well oxygenated seafloor to 2 enhanced water runoff or decreased evaporation or both and oxygen depleted bottom waters we suggest that this deterministic sedimentary cyclicity could be explained by periodic orbital climatic cycles in tune with the milankovitch cycles within this scenario the latest cenomanian bonarelli level is an exceptional event marked by a large positive 13c spike it is characterized by high to very high fertility conditions in surface waters caused by increased upwelling that engendered high nutrient levels in near surface waters the enhanced production of organic matter was in excess for the oxygen available at the bottom floor thus allowing the organic matter to accumulate in the sediments

scattering of gps signals from the ocean with wind remote sensing application a theoretical model that describes the power of a scattered global positioning system gps signal as a function of geometrical and environmental parameters has been developed this model is based on a bistatic radar equation derived using the geometric optics limit of the kirchhoff approximation the waveform i e the time delayed power obtained in the delay mapping technique depends on a wave slope probability density function which in turn depends on wind waveforms obtained for aircraft altitudes and velocities indicate that altitudes within the interval 5 15 km are the best for inferring wind speed in some regimes an analytical solution for the bistatic radar equation is possible this solution allows converting trailing edges of waveforms into a set of straight lines which could be convenient for wind retrieval a transition to satellite altitudes together with satellite velocities makes the peak power reduction and the doppler spreading effect a significant problem for wind retrieval based on the delay mapping technique at the same time different time delays and different doppler shifts of the scattered gps signal could form relatively small spatial cells on sea surface suggesting mapping of the wave slope probability distribution in a synthetic aperture radar sar fashion this may allow more accurate measurements of wind velocity and wind direction

trace metals and organic geochemistry of the machiques member aptian albian and la luna formation cenomanian campanian venezuela abstract two proposed source rock sequences in the lower aptian albian and the upper cenomanian campanian cretaceous sediments of the perija range maracaibo basin were geochemically analyzed in order to find environmentally controlled characteristic fingerprints trace metals and sulfur concentrations were found to be closely related with the physicochemical conditions during deposition of the rocks based on trace metal analyses and sulfur relationships with toc the aptian albian sequence machiques member shows alternate oxic and anoxic episodes close to the bottom water surface where mixed marine and terrestrial organic matter were deposited the cenomanian campanian sequence la luna formation persistently shows anoxic euxinic conditions that allowed the preservation of marine organic matter ratios of trace metals v mo and zn characterize both cretaceous sedimentary columns however some limitations are visualized in using trace metals as correlation tools in further geochemical studies biomarker ratios are related to the organic matter type and lithology some specific ratios and individual compounds allow a clear differentiation between these two sequences and offer in the context of 13 c an excellent tool for further oil source rock correlation studies

carbon and oxygen isotope stratigraphy of the english chalk and italian scaglia and its palaeoclimatic significance a detailed carbon and oxygen isotope stratigraphy has been generated from upper cretaceous coastal chalk sections in southern england east kent culver cliff isle of wight eastbourne and seaford head sussex norfolk coast and the british geological survey bgs trunch borehole norfolk data are also presented from a section through the scaglia facies exposed near gubbio italian apennines wherever possible the sampling interval has been one metre or less both the chalk and scaglia carbon isotopic curves show minor positive excursions in the mid cenomanian mid and high turonian basal coniacian and highest santonian lowest campanian there is a negative excursion high in the campanian in chalk sections that span that interval the well documented cenomanian turonian boundary spike is also well displayed as is a broad positive excursion centred on the upper coniacian a number of these positive excursions correlate with records of organic carbon rich deposition in the atlantic ocean and elsewhere the remarkable similarity in the carbon isotope curves from england and italy enables cross referencing of macrofossil and microfossil zones and pinpoints considerable discrepancy in the relative positions of the turonian coniacian and santonian stages the oxygen isotope values of the various chalk sections although showing different absolute values that are presumably diagenesis dependent show nonetheless a consistent trend the east kent section which is very poorly lithified indicates a warming up to the cenomanian turonian boundary interval then cooling thereafter regional organic carbon burial documented for this period is credited with causing drawdown of co 2 and initiating climatic deterioration inverse greenhouse effect data from other parts of the world are consistent with the hypothesis that the cenomanian turonian temperature optimum was a global phenomenon and that this interval represents a major turning point in the climatic history of the earth

trace elements as palaeoenvironmental markers in strongly mature hydrocarbon source rocks the cretaceous la luna formation of venezuela abstract the late cretaceous la luna formation is the main hydrocarbon source rock formation in venezuela in the lake maracaibo area the formation shows a steep maturation gradient affecting sedimentary organic matter om and clay minerals related to local burial history and thrusting events the influence of the gradient is examined through geochemical organic and inorganic and mineralogical investigations carried out on samples from five cored boreholes in the maracaibo basin the analytical procedure comprises rock eval pyrolysis vitrinite reflectance measurement palynofacies observation major and trace element content determination performed on bulk rock samples or after a sequential leach protocol dop calculation and the examination and analysis of clay mineral assemblages the maturation gradient seems to have had no effect upon the distribution of the trace elements referred to as proxy indicators for palaeodepositional conditions of om rich sediments ba p v mo ni co cu cd cr and mn consequently trace elements appear to be reliable palaeoenvironmental markers they indicate that during the la luna fm deposition the water column must have had variable conditions with high primary production near the surface and the correlative development of euxinic conditions at the bottom this provides further arguments for an upwelling system affecting the northern platform of south america during late cretaceous time the relative scarcity of reactive iron in the depositional environment must have taken an active part in a process involving sulphur and acting on the environmental conditions as well as on om vulcanisation this process favours aliphatic om storage and may be relevant for many other om rich facies or hydrocarbon source rocks

late cretaceous upwelling and anoxic sedimentation in northwestern south america abstract black shales and bituminous limestones were widely deposited in northwestern south america during the maximum transgression of late cretaceous seas these cenomanian to santonian campanian anoxic sediments are distributed in two main subprovinces thick chert and phosphorite accumulated in the trough subprovince landward of a possibly partially emergent cordillera central colombia only minor intercalations of chert were deposited in the platform subprovince lying northward in the maracaibo basin northwestern venezuela faunal evidence depauperate benthic fauna planktic foraminiferal assemblages high dominance clupeoid fish assemblages and sedimentological evidence suggest anoxic condition prevailed throughout the region probably the result of dynamic upwelling in the trough subprovince but the reflection of a global anoxic event within the platform subprovince

palaeoceanographic and palaeoclimatic inferences from late cretaceous planktonic foraminiferal assemblages from the exmouth plateau odp sites 762 and 763 eastern indian ocean the evolution of planktonic foraminifera during the late cretaceous is marked in the santonian by the disappearance of complex morphotypes the marginotruncanids and the contemporary increasing importance and diversification of another group of complex taxa the globotruncanids upper turonian to lower campanian planktonic foraminiferal assemblages from holes 762c and 763b ocean drilling program leg 122 exmouth plateau 47 s palaeolatitude were studied in detail to evaluate the compositional variations at the genus and species level based on the assumption that in the cretaceous oceans as in the modern any faunal change was associated with changes in the characteristics and the degree of stability of the oceanic surface waters three major groups were recognised based on gross morphology and following the assumption that cretaceous planktonic foraminifera although extinct had life history strategies comparable to those of modern planktonics 1 r selected opportunists 2 k selected specialists 3 r k intermediate morphotypes which include all genera that display a range of trophic strategies in between opportunist and specialist taxa although planktonic foraminiferal assemblages are characterised by a progressive appearance of complex taxa this trend is discontinuous variation in number of species and specimens within genera has allowed recognition of five discrete intervals each of them reflecting different oceanic conditions based on fluctuations in diversity and abundance of the major morphotypes planktonic forms show cyclical fluctuations in diversity and abundance of cold r strategists and warm taxa k strategists perhaps representing alternating phases of unstable conditions suggesting a weakly stratified upper water column in a mesotrophic environment and well stratified surface and near surface waters indicating a more oligotrophic environment interval 1 middle turonian to early coniacian in age is dominated by the r k intermediate morphotypes which alternate with r strategists these cyclical alternations are used to identify three additional sub intervals interval 2 aged middle to late coniacian is characterised by the increasing number of species and relative abundance of k strategists after this maximum diversification the k strategists show a progressive decrease reaching a minimum value in interval 3 early to late santonian which corresponds to the extinction of the genus marginotruncana in the interval 4 latest santonian in age the k strategists represented mainly by the genera globotruncana increase again in diversity and abundance the last interval 5 early campanian is dominated by juvenile globotruncanids and r strategists which fluctuate in opposite phase the positive peak interval 2 related to the maximum diversification of warm taxa k strategists in the coniacian seems to correspond to a warmer episode it is followed by a marked decrease in the relative abundance of warm taxa k strategists crisis with a minimum in the late santonian interval 3 reflecting a decrease in temperature detailed analysis of faunal variations allows the santonian faunal turnover to be ascribed to a cooling event strong enough to cause the extinction of the marginotruncanids

savers a simulator of gnss reflections from bare and vegetated soils the mean power of the reflected global navigation satellite system gnss signals acquired by a gnss reflectometry gnss r receiver can be modeled through the integral bistatic radar equation by weighting the contributions of all scatterers on the surface by the system impulse response the geophysical properties of the scattering surface affect the magnitude of the reflected navigation signals through the bistatic scattering coefficient which in case the observed surface is land is a function of the soil dielectric properties surface roughness and vegetation cover in this paper the gnss r signal simulator developed in the framework of the land monitoring with navigation signal leimon project supported by european space agency is presented the simulator is able to predict the power reflected by land taking as input the system and observation parameters as well as the land surface parameters the latter are used to simulate both the coherent and the incoherent scattering taking advantage of widely used theoretical models of bistatic scattering from bare soils and vegetated surfaces first the geometrical formulation is discussed and then the problem of polarization mismatch due to real antennas at circular polarization is faced following the polarization synthesis approach finally a comparison with some experimental data collected during the leimon campaign is presented the simulations display the same trend of the experimental data thus showing that the simulator can be used as an efficient tool for the interpretation of gnss r measurements

lipids of aquatic organisms as potential contributors to lacustrine sediments ii abstract the relationship between the lipid composition of organisms in the water column of an eutrophic lake and the lipid composition of underlying sediments previously examined for n alkanols and steroids is now reported for hydrocarbons ketones and carboxylic acids the n c7 alkane and alkenoic acids from two primary sources are rapidly metabolized in the water column and surficial sediment bacterial biomarkers including hopenes and i ai branched fatty acids were detected in the photosynthetic bacterial layer occurring just above the sediment water interface within the sediment the apparent conversion of free n alkanes alkan 2 ones and hydroxy acids to the corresponding bound form is noted microbiological oxidation of n alkanes to alkan 2 ones is supported by the detection of the intermediate alkan 2 ols with a distribution similar to that of the ketones the geochemistry of sediment deposited c 1900 prior to biological study of the site was interpreted from stable biomarkers and the diagenetic changes recognised in the study of contemporary deposition a qualitative difference in algal input to the older sediment is inferred from the low 7 sterol content and presence of 2 6 10 trimethyl 7 3 methylbutyl dodecane however there was still significant dinoflagellate input as indicated by the presence of 4 methylsterols a difference in higher plant input to the older sediment indicated from the n alkane alkene and triterpenoid ketone distributions is consistent with the recent development of tree cover

perylene occurrence alkylation and possible sources in deep ocean sediments abstract 81 deep ocean sediment samples obtained from the dsdp ipod program legs 63 66 and six gravity cores from dsdp ipod leg 64 guaymas basin gulf of california site survey cruise sio were analyzed for perylene s perylene was found to be most abundant in anoxic diatomaceous sediments containing moderate amounts of silts and or clays elevated perylene yields normalized to organic carbon contents coincided with enhanced preservation of autochthonous tetraterpenoid and tetrapyrrole pigments indicating a requirement of anoxia in the formation of perylene strongly euxinic conditions correlate with decreased perylene yields but not its total absence as found for strongly aerobic deposition and or redeposition perylene alkylation occurs in response to increasing in situ temperatures alt sub bottom depth this alkylation was found to begin with the generation of methyl c 1 perylene and to eventually yield a perylene alkyl perylene homologous series in decreasing abundance through the equivalent of c 3 trimethyl methyl ethyl propyl perylene the realm of most intense perylene alkylation for quaternary or pliocene miocene sediments corresponds with present in situ temperatures of 40 50 c or 30 35 c respectively thus the degree of perylene alkylation may represent an organic indicator for the thermal history of immature sediments geological phenomena such as reworking and igneous intrusions were found to complicate downhole perylene alkylation patterns a substituted c4h7o2 perylene was isolated from several anoxically deposited diatomaceous oozes and may represent one of the many possible perylene precursors the possible source compounds and biota for sedimentary perylene are discussed in light of the present study and review of past reports

scobi veg a generalized bistatic scattering model of reflectometry from vegetation for signals of opportunity applications scobi veg stands for signals of opportunity coherent bistatic scattering model for vegetated terrains it simulates polarimetric reflectometry of vegetation canopy over a flat ground using a monte carlo scheme the model is aimed at assessing the value of navigation and communication satellite signals of opportunity in a range of frequencies from p to s bands for remote sensing of a number of geophysical land parameters such as soil moisture and biomass a fully polarimetric expression for bistatic scattering from a vegetation canopy is first formulated for a general case and is then specialized to the practical case of ground based low altitude platforms with passive receivers overlooking vegetation using the signals transmitted from large distances using analytical wave theory in conjunction with distorted born approximation the transmit and receive antenna effects i e polarization crosstalk mismatch orientation and altitude are explicitly accounted for the forward model developed here enables the understanding of the effect of different geophysical parameters and system configurations on the coherent and incoherent components of the reflected signatures it can thus help developing robust inverse algorithm for extraction of soil moisture and biomass the model is applied to p band signals of geostationary communication satellites to describe polarimetric reflections from tree canopies as observed from down looking platforms at various altitudes the relative contributions of diffuse and specular scattering on total reflected power and reflectivity are quantified for various observing scenarios

formation of holocene sedimentary laminae in the black sea and the role of the benthic flocculent layer holocene black sea sediments recovered in 1988 and 1993 from box cores and gravity cores were analyzed geochemically microscopically and with backscattered electron imagery bsei in order to determine the temporal geochemical and sedimentological relationships between the benthic flocculent layer often referred to as the fluff layer and the formation of underlying laminated unit i sediments existence of a permanent benthic fluff layer in the black sea basin is suggested acting as a geochemical transition layer within which all sedimentary particles are hydraulically sorted and particles subject to dissolution or organic remineralization are altered prior to accumulation we propose that particle residence time within the benthic fluff layer is a key factor in determining sedimentary microfabric and geochemical composition of laminated unit i sediments we present a schematic model depicting the above relationships and use it to propose a paleoflux scenario for laminae formation in the unit ii sapropel

land geophysical parameters retrieval using the interference pattern gnss r technique in the past years the scientific community has placed a special interest in remotely sensing soil moisture and vegetation parameters radiometry and radar techniques have been widely used for years global navigation satellite systems opportunity signals reflected gnss r over the earth s surface are younger but they have already shown their potential to perform these observations this paper presents a gnss r technique based on global positioning system gps measurements that allows the retrieval of several geophysical parameters from land surfaces this technique measures the power of the interference signal between the direct gps signal and the reflected one after scattering over the land so it is called interference pattern technique ipt this paper presents the results obtained after applying the ipt for topography soil moisture and vegetation height retrievals over vegetation covered soils

thermal evolution of cretaceous tethyan marine waters inferred from oxygen isotope composition of fish tooth enamels 1 the evolution of subtropical 30 35 n upper ocean temperatures through the cretaceous is inferred from the oxygen isotope compositions of 64 fish teeth enamel coming from the western tethyan platform mean 18o values of 22 at the berriasian valanginian boundary decrease with oscillations to 18 5 around the cenomanian turonian boundary and progressively increase to 21 5 by the end of the cretaceous the similarity of this oxygen isotope curve for bioapatites from platform environments with those for foraminifera and bulk carbonates that were deposited in deeper waters and at other paleolatitudes indicates that they record global climatic signals major cooling events at the million year scale can be distinguished 1 at the berriasian valanginian boundary and 2 during the earliest late valanginian a third cooling event is detected during the earliest aptian these events already proposed as icehouse interludes during the lower cretaceous are also recorded at subtropical latitudes a progressive warming is identified from the aptian to the cenomanian turonian interval that corresponds to a thermal optimum and then upper ocean temperatures decreased to the maastrichtian minimum isotopic temperatures range from 15 c to 28 c assuming a 18oseawater of 1 for an ice free world taking more realistic 18oseawater values of 0 for tropical waters during glacial periods within the berriasian valanginian interval and earliest aptian or with above average salinities possibly the maastrichtian temperatures are increased by 4 5 c temperature differences between climatic extremes of the valanginian and cenomanian turonian are estimated to have been 10 c latitudinal thermal gradients for the albian cenomanian turonian and maastrichtian were 0 2 0 3 c latitude and thus weaker than modern oceanic values at about 0 4 c latitude

evidence for thermohaline circulation reversals controlled by sea level change in the latest cretaceous fluctuations in oxygen 18 o and carbon 13 c isotope values of benthic foraminiferal calcite from the tropical pacific and southern oceans indicate rapid reversals in the dominant mode and direction of the thermohaline circulation during a 1 m y interval 71 70 ma in the maastrichtian at the onset of this change benthic foraminiferal 18 o values increased and were highest in low latitude pacific ocean waters whereas benthic and planktic foraminiferal 13 c values decreased and benthic values were lowest in the southern ocean subsequently benthic foraminiferal 18 o values in the indo pacific decreased and benthic and planktic 13 c values increased globally these isotopic patterns suggest that cool intermediate depth waters derived from high latitude regions penetrated temporarily to the tropics the low benthic 13 c values at the southern ocean sites however suggest that these cool waters may have been derived from high northern rather than high southern latitudes correlation with eustatic sea level curves suggests that sea level change was the most likely mechanism to change the circulation and or source s of intermediate depth waters we thus propose that oceanic circulation during the latest cretaceous was vigorous and that competing sources of intermediate and deep water formation linked to changes in climate and sea level may have alternated in importance

organic geochemical characterization of santonian to early campanian organic matter rich marls sondage no 1 cores as related to oae3 from the tarfaya basin morocco abstract in addition to previously analyzed sediments of cenomanian to santonian age in the tarfaya sondage no 2 well this study presents the results of a stratigraphically younger interval of santonian to early campanian age in the adjacent well tarfaya sondage no 1 this interval is part of the oceanic anoxic event 3 oae3 which occurred mainly in the atlantic realm due to known high quality source rocks related to oaes i e cenomanian turonian the investigated sample section was tested for the quality quantity and kind of organic matter om describing also the depositional environment the study was carried out by means of i elemental analysis c org caco 3 ts ii rock eval pyrolysis iii vitrinite reflectance measurements iv gas chromatography flame ionization detection gc fid and v gc mass spectrometry gc ms total content of organic carbon c org values for the hydrogen index hi mainly in the range 500 700 mg g c org and s 2 values 10 40 mg g rock support the assumption of a high petroleum generation potential in these upper cretaceous sediments ts c org ratios as well as pristane phytane ratios indicate variable oxygen contents during sediment deposition representing a typical depositional setting for the late cretaceous and are in good agreement with previously analyzed data in the tarfaya basin phyto and zoo plankton were identified as marine sourced all of the investigated early campanian and santonian samples are immature with some tendencies to early maturation these results are based on vitrinite reflectance 0 3 0 4 vr r t max values 409 425 c production indices pi s 1 s 1 s 2 n alkane ratios i e carbon preference index as the deposition of these sediments is time related to oae3 the depositional environment was characterized by oxygen deficiency or even anoxic bottom water conditions this situation was favored during the cretaceous greenhouse climate by limited oxygen solubility in the then warmer ocean water furthermore local factors related to nutrient supply and primary bioproductivity led to the exceptionally thick upper cretaceous organic matter rich sedimentary sequence of the tarfaya basin

paleoceanographic reconstruction of the late cretaceous oil shale of the negev israel integration of geochemical and stable isotope records of the organic matter the levantine high productivity system was an extensive coastal upwelling that operated in the late cretaceous along the se tethyan margin this study focuses on the top phosphate member of the mishash formation and the oil shale member osm of the ghareb formation latest campanian early maastrichtian which represent the last phase of this high productivity system in the negev israel bulk organic matter toc 13corg 15norg c n and pristane phytane pr ph ratios were studied for reconstruction of seafloor and water column depositional environments our records indicate a gradual decrease with time in surface water productivity in the osm and a marked weakening at the overlying marl member high c n ratio along with relatively low 15norg 4 to 6 and 13corg 29 to 28 probably reflect significant diagenetic preferential loss of nitrogen rich organic compounds enriched with 15n and 13c isotopes e g proteins this along with the low pr ph values 0 11 0 7 indicate oxygen depleted bottom water anoxia dysoxia during the deposition of the top phosphate member and the osm the moderate gradual upward increase in 15norg and in pr ph values and the decrease of toc and c n values from the top phosphate member through the osm indicate transition from anoxic phosphate lower osm to dysoxic middle upper osm conditions this environmental trend is consistent with co occurring foraminiferal assemblages in the studied succession and implies that the benthic species in the negev sequence were adapted to persistent minimum oxygen conditions by performing complete denitrification as recently found in many modern benthic foraminifera

sea surface state measured using gps reflected signals we discuss an airborne experiment aimed to establish the potential of the paris concept passive reflectometry and interferometry system to retrieve small features in the sea surface topography the date and location were chosen to coincide with a topex poseidon t p overflight the signals of the global positioning system gps reflected off the sea surface are tracked and compared to the directly received ones to compute the relative delays the features detected in the peak tracking are likely caused by topographic and sea roughness variations while very promising these results open the challenge to use additional information to appropriately separate both contributions