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This paper presents an integrated petrographic–geochemical–geomechanical study of the growth mechanisms of carbonate and chert concretions observed at outcrop and core from the Upper Cretaceous to Eocene organic-rich carbonate mudrocks, central Jordan. It provides evidence for displacive and replacive concretion growth from the analysis of primary lithological characteristics, compaction strain and deformation structures associated with concretion growth. Concretions were analysed to determine the primary lithological controls on their development and the measurement of strain in the host rock to develop a method for constraining the growth mode and their paragenesis. Concretions exhibit either a replacive or displacive growth mode largely dependent on the original host lithology. Displacive concretions exhibit irregular shapes and semi-fibrous internal structures in contrast to regular shapes and microcrystalline textures observed for replacive concretions. Cement fraction is high in both carbonate concretion types, indicating early formation in high-porosity sediments at shallow burial depths. The strain field around displacive concretions is vertically asymmetrical. Conversely, it is symmetrical with uniform differential compaction for the replacive concretions. Evidence for displacive growth comes from triangular areas of chert at the lateral margins of some carbonate concretions, interpreted as areas of reduced strain. Another indicator is the forced asymmetrical folding of heterolithic host rocks around displacive concretions, with displacive carbonate units separated by trace laminae of the original (chert) beds. Enveloping chert beds exhibit early-formed radial silica fractures with increased aperture size in the areas of maximum curvature. Carbon isotopic signatures of carbonate concretions show a strong correlation between concretion centres and host rock, suggesting a relatively shallow depth (first few tens of metres) of initial growth. Carbonate concretions are interpreted to have formed at shallow depths in the presence of alkaline pore waters rich in dissolved organic carbon in the presence of Mg2+ ions, available organic matter and redox-sensitive metals such as U and Mo. A paragenetic history for the different concretion types is presented.

An integrative multi proxy approach based on lithology, microfacies, bulk rock composition, total organic carbon (TOC), and δ13Ccarb was used to estimate southeastern Tethys sea level fluctuations during the deposition of the Maastrichtian-Danian oil shales in Jordan. Clay mineral assemblages were used as proxies to determine climatic variation induced sediment supply during the Cretaceous/Paleogene boundary (K/Pg) interval. The results from two cores (OS-02, Jafr Basin, southeast Jordan; OS-28 Azraq-Hamza Basin, central-east Jordan) reveal four major intervals of distinctive bulk rock composition reflecting sea level changes. Interval I (earliest Maastrichtian) with a low sea level and the formation of dolomites and a high detrital quartz input predates the oil shales. Intervals II and III in core OS-02 and interval II in core OS-28 represent the highest relative sea level following the Early Maastrichtian sea level rise on the Arabian Platform. Intervals III (core OS-02) and II (core OS-28) coincide with the highest organic matter deposition. Interval IV (core OS-02) and intervals III and IV (core OS-28) relate to the sea level regression-transgression cycle in the latest Maastrichtian through Danian and are marked by a large drop in the TOC content. Increased terrestrial influx during sea level lows is evident from two peaks/intervals of major negative δ13Ccarb values in core OS-28. Based on clay mineralogy it can be differentiated between warm/humid, warm/cool seasonally alternating, and cool/arid climates. When bulk rock composition is used as a sea level proxy, clay mineral assemblages from both cores reveal the dominance of warm and humid climate or, alternatively, warm/cool seasonal alternations during high sea levels (II and III core OS-02; II and IV core OS-28), while periods of arid and cool climate correspond to lower sea levels. The sea level changes and climatic variations deduced from the Jordanian oil shale successions are in agreement with the long term variations from the Egyptian Western Desert sections (southeastern Tethys), and the Tunisian El-Kef section (southweastern Tethys). Moreover, the sea level changes identified relate to the regional changes on the Arabian platform during the Maastrichtian-Danian.

We present the first multiple sulfur isotope study (32S, 33S, 34S, 36S) of bulk kerogen sulfur (KS) and disulfides (‘chromium-reducible sulfur’, CRS) from the oil shale of the Umm Rijam Chert-Limestone and Muwaqqar Chalk Marl Formation, Jordan (Late Cretaceous to Early Eocene, appr. 50–70 Ma). Analysis of the sulfur isotopic composition of KS (δ34SKS) shows values ranging from 0.3 to 17.9‰, which are 34S-enriched compared to the δ34SCRS ranging from −23.5 to −3.7‰. Values for CRS and KS are significantly 34S-depleted compared to seawater sulfate sulfur which suggests a major input of early-diagenetic, microbially-generated sulfide. A minor contribution of assimilated seawater sulfate to KS is assumed. The 34S-enrichment of KS compared to CRS can be partly explained by (1) sulfide oxidation to intermediate sulfur species prior to its incorporation into organic material, by (2) fractionations during organic sulfur generation, as well as by (3) a post-depositional timing of formation. Additionally, we hypothesize, based on parallel depth trends of maturity parameters (e.g., vitrinite reflectance) and δ34SCRS and δ34SKS values, that the sulfur isotopic compositions were influenced by thermal maturation (catagenesis). We suggest that the CRS pool comprises a contribution of sulfide released during the thermal decomposition of KS. Overall, our study highlights the importance of organic sulfur in sulfur isotopic studies and the potential of multiple sulfur isotope analyses in maturated sedimentary successions.

This study is based on Maastrichtian and Danian oil shales of a cored well located in the Jafr Basin in central Jordan. Studied sedimentary rocks consist of alternations of monotonous bituminous marls, phosphatized marls, occasional dolomite, black chert, and limestone concretions. The main characteristics of these deposits are the high values of the total organic carbon (TOC) which fluctuate between 2.8 and 32.1 wt%. Benthic foraminifera were studied quantitatively in order to reconstruct environmental changes across the Maastrichtian and early Danian. Three clusters of benthic foraminifera, showing different assemblage compositions on the species level, were distinguished. Each of these assemblages is characterized by changes of diversity indices and abundances, indicating fluctuations of the bottom water oxygenation and organic matter fluxes. Water-depth preferences based on three associations and marker species of benthic foraminifera indicate an estimated paleodepth from middle to outer neritic (∼50–200 m) during the Maastrichtian and Danian. During the Maastrichtian, Anomalinoides praeacutus is the dominant benthic foraminifera species characterized by high abundances. A short decline of A. praeacutus, observed in calcareous nannofossil biozone UC18/19 (lower Maastrichtian), is compensated by an increase of Anomalinoides umboniferus. Abundance fluctuations of benthic foraminifera included in the Buliminacea (Sitella fabilis, Elhasaella alanwoodi, Neobulimina canadensis, Reussella aegyptiaca) are recorded from the assemblages. The taxonomic composition of the assemblages and the varying TOC values indicate low oxygen bottom-water conditions under high organic flux across the Maastrichtian. A moderate change is documented for the Danian, where A. praeacutus continues to dominate the assemblages, but Siphogenerinoides eleganta and Uvigerinella spp. are less common. These benthic associations along with a decrease of the TOC content suggest a gentle increase of the bottom water oxygenation with moderate organic fluxes.

Summary This study explores the use of novel data analysis techniques such as supervised machine learning algorithms to unlock the full potential of large geochemical datasets

Summary This work demonstrates novel insights into Neoproterozoic-Cambrian petroleum systems and highlights the application of aromatic molecular proxies, which can record information that may be overlooked if only utilizing conventional hopane and sterane biomarkers.

Organic matter (OM) rich marls were deposited in several intrashelf basins in Jordan (e.g. Yarmouk Basin, Lajjun Basin, Azraq-Hamza Basin, Jafr Basin, Eshidiyya Basin) on the southeastern Tethyan margin during the Maastrichtian to middle Eocene . Factors like surface water productivity fueled by upwelling and sea level changes affected their deposition. Potential effects of climatic changes have not been determined yet. We present the first stable carbon and oxygen isotope records of Maastrichtian-Danian oil shales from the Azraq-Hamza and Jafr Basins in south- and central-east Jordan. The δ 13Ccarb curves were time-calibrated based on calcareous nannofossil biostratigraphy . Eight notable excursions were identified in the Jordanian Maastrichtian sections. These were correlated with the documented Maastrichtian δ 13Ccarb events in the (sub) tropical sections of Italy and the western Pacific: the Campanian-Maastrichtian boundary Events 4 and 5 (CMBE-4, CMBE-5), the Middle Maastrichtian Events 1 to 3 (MME-1 to MME-3) and the Cretaceous-Paleogene boundary Events 1 to 3 (KPgE-1 to KPgE-3). Signs of the Latest Danian Event (LDE) were recognized as well. Total organic carbon (TOC) data exhibit a complex relationship with the δ 13Ccarb proxy record. The δ13Ccarb signals are repeatedly dampened due to the OM oxidation and subsequent 12 C release. The effect of short term climate changes is observed, but is not always straight forward. Long term climate changes had indirect effects on bottom water oxygenation and OM preservation via sea level changes. The δ 18Ocarb data from both sections reveal minor temperature changes in the Maastrichtian. Slight warming is observed in the MME interval. A potential increase of the paleotemperature is reported from the Azraq-Hamza section occurring in the latest Maastrichtian to earliest Danian.

© 2018 Cushman Foundation. All rights reserved. This study presents benthic foraminiferal data from two sedimentary successions across the Paleocene-Eocene Thermal Maximum (PETM) from Jordan. Calcareous nannofossil biozones NP9a, NP9b, and NP10 of latest Paleocene and earliest Eocene age were encountered in proximal (core OS-01) and distal (core OS-28) sites. Lithologically, the investigated sequence consists of marls, shales, and limestones attributed to the Muwaqqar Chalk-Marl Formation and the Urn Rijam Chert Limestone Formation. The δ 13 C org curve records the typical carbon isotope excursion (CIE) and shows four distinctive intervals (pre-CIE, CIE-"core", CIE "recovery", post-CIE) over the entire PETM interval in both cores. In the pre-CIE interval, the more proximal site (OS-01) shows high abundances of Neoeponides duwi co-occurring with an outer neritic Midway-type fauna. The fauna indicates mesoto eutrophic conditions in a middle to outerneritic setting. The more distal site (OS-28) is characterized by outer-neritic to upper-bathyal taxa (e.g., Cibicides pseudoacutus, Gavelinella beccariiformis, Nuttallides truempyî) suggesting well-ventilated, oligo-to mesotrophic seafloor conditions. The earliest Eocene corresponds to the CIE-"core" interval and is marked by a negative δ 13 C org signal, high TOC, low CaCO 3 contents, and near absence of benthic foraminifera. Oxygen deficiency in bottom waters with increased organic flux is the most likely scenario to explain the elevated organic content at the seafloor. The subsequent CIE-"recovery" interval of early Eocene age is marked by a restoration of oxygenated seafloor conditions. The proximal site is characterized by a relatively elevated TOC content and high abundance of Lenticulina spp., Valvulineria scrobiculata and common Anomalinoides zitteli, suggesting moderate oxygen conditions and mesotrophic bottom waters. The distal site is characterized by low TOC content and the presence of Lenticulina spp., Valvulineria scrobiculata, Anomalinoides zitteli and Oridorsalis plummerae, indicating a normalization of the organic flux and moderate oxygen concentrations near the seafloor. The post-CIE interval is marked by low TOC content in both cores. Benthic foraminifera include abundant Anomalinoides zitteli and common Lenticulina spp., Valvulineria scrobiculata, Oridorsalis plummerae, Cibicidoides rigidus, Cibici-doides pharaonis, and Anomalinoides praeacutus in the proximal setting. Mesotrophic conditions and a better ventilation of bottom waters are suggested for this interval. Lenticulina spp., Valvulineria scrobiculata, and Oridorsalis plummerae are also associated with the post-CIE interval in the distal site, suggesting similar mesotrophic conditions with renewed oxygenation in bottom waters. ispartof: JOURNAL OF FORAMINIFERAL RESEARCH vol:48 issue:2 pages:100-120 status: published

Core OS-28 located in central Jordan offers an expanded record of calcareous nannofossils and benthic foraminifera for the early Eocene of the southern Tethys. The oil shale succession of the studied interval covers calcareous nannofossil biozones NP10, NP11, NP12 and NP13. Microfossils document the biotic response of calcareous nannofossils and benthic foraminifera to short and long term warming trends of the early Eocene following the Paleocene-Eocene Thermal Maximum (PETM). On a global scale, two early Eocene short term shifts to higher atmospheric CO 2 concentration are recorded by negative δ 13 C excursions. These are known as Eocene Thermal Maximum 2 and 3 (ETM2, ETM3). Stable isotope records (δ 13 C org , δ 13 C carb , δ 18 O carb ) from the study area do not show these negative excursions, which elsewhere can be correlated with the two hyperthermal events known from early Eocene successions. The absence of negative δ 13 C signals otherwise typical for ETM2 and ETM3 is explained by a diagenetic alteration of the isotope signal after deposition. High abundances of the nannofossil taxon Sphenolithus spp. in biozone NP10 indicate less fertile conditions for this interval than for the overlying biozone NP11. Throughout biozones NP11 to NP13 Coccolithus pelagicus and Toweius spp. are the dominant taxa of the assemblages, suggesting a mesotrophic environment. Surface waters experienced a temperature change from warm to moderate-warm. The benthic foraminifera in calcareous nannofossils biozone NP10 and in the lower part of NP11 reflect oligo-mesotrophic and moderate to well oxygenated bottom water conditions. Throughout the upper part of biozones NP11, NP12 and NP13, the benthic foraminifera are characterized by an increasing abundance of Anomalinoides zitteli , Lenticulina spp. and Valvulineria scrobiculata . This coincides with enriched total organic matter content (TOC), indicating a shift to mesotrophic conditions and a moderate oxygen supply of the bottom waters. Based on the micropaleontological observations made in core OS-28 the early Eocene is first characterized by an increase and subsequently by a decrease of nutrients and oxygen. The composition of both, benthic and planktic communities was rather controlled by variations of regional environmental parameters than by global ones. These include strong runoff, climatic variability and the architecture of the basin.

We integrate previously published data from geochemistry, clay mineralogy, and benthic foraminifera with new findings from calcareous nannofossils and the sulfur content to reconstruct the variations of bottom and surface water conditions resulting from climate changes in the Jafr Sub-basin (Jordan). The fluctuation of the organic matter content recorded from Maastrichtian and Danian oil shales of a cored section, is seen as a response to nutrient fluxes, inducing changes in primary productivity. Bacterial workover and enrichment played a secondary role. The benthic foraminifera and calcareous nannofossils reflect oxygen depleted bottom waters and ecologically stressful surface waters. The preservation of organic matter and organic matter bound sulfur, which dominates almost throughout the entire Maastrichtian, is linked to warm-humid climatic conditions. A slight increase of the oxygen content of bottom and surface waters, which has been recorded for the latest Maastrichtian and Danian, is associated with warm-arid conditions. The biota response to these changes is documented by the extinction of most calcareous nannofossil species across the Cretaceous-Paleogene boundary, while benthic foraminifera were less affected. The short- and long-term climatic variations during the Maastrichtian-Danian interval suggest the following scenario. Riverine influx in combination with an upwelling system provided the nutrient input fueling the primary productivity of the southeastern Tethyan surface waters during the late phase of extended shelf flooding.

Petroleum source rocks are strongly enriched in organic carbon (OC), and their trace metal (TM) contents often reach low-grade ore levels. The mechanisms leading to these coenrichments are important for understanding how extreme environmental conditions support the formation of natural resources. We therefore studied organic-rich Eocene marls and limestones (oil shale) from the central Jordan Amzaq-Hazra subbasin, part of a Cretaceous–Paleogene shelf system along the southern Neo-Tethys margin. Geochemical analyses on two cores show highly dynamic depositional conditions, consistent with sedimentological and micropaleontological observations. Maximum and average contents, respectively, in OC (~26 and ~10 wt%), sulfur (~7 and ~2.4 wt%), phosphorus (~10 and ~2 wt%), molybdenum (>400 and ~130 ppm), chromium (>500 and ~350 ppm), vanadium (>1600 and ~550 ppm) and zinc (>3800 and ~900 ppm) are exceptional, in particular without any indication of hydrothermal or epigenetic processes. We propose a combination of two processes: physical reworking of OC- and metal-rich 30 material from locally exposed Cretaceous–Paleogene sediments (as supported by reworked nannofossils), and high marine productivity fueled by chemical remobilization of nutrients and metals on land that sustained anoxic-sulfidic conditions. Burial of high-quality organic matter (hydrogen index 600–700 mgHC/gOC) was related to strongly reducing conditions, punctuated by only short-lived oxygenation events, and to excess H2S, promoting organic matter sulfurization. These processes likely caused the OC and TM coenrichments in a high-energy shallow-marine setting that contradicts common models for black shale formation, but may explain similar geochemical patterns in other black shales.

The Paleocene-Eocene Thermal Maximum (PETM) is known as an approximately 200 kyr long lasting interval of extreme global warming accompanied by major alterations in the ocean-atmosphere system. These include a negative carbon isotope excursion, intense carbonate dissolution and biotic changes of marine floras and faunas. The current study reports the response of calcareous nannofossils across the Paleocene-Eocene boundary in a paleoshelf setting in Jordan (core OS-28), clearly marked by a negative δ 13 C org excursion and the occurrence of characteristic “excursion taxa” (e.g., Discoaster araneus , Rhomboaster spp., Coccolithus bownii ). While this section suffers from intense dissolution at the onset of the event and the peak of the isotopic excursion, it retains well-preserved, diverse nannofossil assemblages from the pre-PETM, PETM recovery and post-PETM intervals. These assemblages are dominated by two taxa of inferred mesotrophic affinities ( Coccolithus pelagicus , Toweius spp.) and show only low abundances of oligotrophic taxa ( Discoaster spp., Fasciculithus spp., Sphenolithus spp.). Overall, there appear to be only relatively low-level changes in the general assemblage composition across the PETM. During the post-PETM, however, there was a gradual decrease in relative abundance of C. pelagicus and Toweius spp. This decline co-coccured with a relative increase of Coccolithus bownii and Coccolithus foraminis , and in its later phase was accompanied by an increase in the relative abundance of Sphenolithus spp. These changes, indicate a possible shift towards less fertile conditions following the hyperthermal event. The relatively muted signal of biotic change associated with the PETM interval at this site was partly a consequence of poor preservation within the key sequence of the studied core. On the other hand, the low signal may also be indicative for local environment processes, such as variations in riverine sourced nutrients, salinity, turbidity. Operating on a regional scale, these local factors overrode the direct and indirect temperature signals that are the dominant control on nannofossil communities across the PETM in open ocean sites. Finally, the assemblages from the Jordan section highlight further the overall spatial heterogeneity in reported responses of shelf area communities to the PETM interval. These heterogeneities have been observed in shelf assemblages from Tanzania, New Jersey and the Tethyan margins, which again points to the strong influence of regional controls like river input in more marginal settings.

© 2017 Elsevier Ltd The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding petroleum systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. In general, clumped isotope measurements indicate plausible formation temperatures for abiotic, thermogenic, and microbial methane in many geological environments, which is encouraging for the further development of this measurement as a geothermometer, and as a tracer for the source of natural gas reservoirs and emissions. We also highlight, however, instances where clumped isotope derived temperatures are higher than expected, and discuss possible factors that could distort equilibrium formation temperature signals. In microbial methane from freshwater ecosystems, in particular, clumped isotope values appear to be controlled by kinetic effects, and may ultimately be useful to study methanogen metabolism.

Large distance correlation of sedimentary organic rich facies units in Jordan has been established by means of calcareous nannofossil biostratigraphy. Based on a biostratigraphic framework, a better understanding of the deposition and distribution of Maastrichtian to Eocene oil shales is obtained. A total of 812 samples representing 29 wells located across Jordan were studied for calcareous nannofossil biostratigraphy. The results reveal major regional changes in paleogeography leading to a change in oil shales distribution in time. The tectonic settings have been determined for four different oil shale sequences of Maastrichtian, Paleocene, Early Eocene and Middle Eocene age. Large variations in thickness over short distances indicate syndepositional subsidence control in several fault bound sedimentary sub-basins. During the Early Maastrichtian transgression, a thick oil shale dominated succession was accumulated in the south of Jordan. This transgression continued into the Paleocene as represented by a thick sequence of oil shales in nannofossil Zone NP 3. In the Late Paleocene, the gradual progradation of the oil shale facies from south to north coincided with an uplift of the Sirhan Sub-basin in east Jordan. Accordingly, the oil shale distribution varies locally and shows a scattered geographic distribution in the Late Paleocene. An up to 60 m thick succession of Early Eocene oil shales was found in central Jordan. Localized restricted conditions, which prevailed during the Ypresian–Lutetian transition (nannofossil Zone NP 14), were caused by the subsidence of the Azraq-Hamza and Sirhan sub-basins. These movements resulted in thick oil shale accumulation in the southeastern and central parts of Jordan. A gradual relative sea level fall during the Bartonian resulted in a prograding and thinning of the oil shale facies from west to east in central Jordan.

Oil-shale beds formed under anoxic conditions that were controlled by various local, regional and global factors. The Jordanian oil shales, which were deposited during the Late Cretaceous to Eocene, are considered as an example for the interplay of these factors. Two cores of organic-rich marls were investigated and analyzed with respect to their lithology, ichnofabrics and carbonate microfacies. The first core (OS-01, 183.3 m; South Jordan) is of Late Cretaceous age, the second one (OS-23, 256.3 m; Central Jordan) is of Eocene age. Our studies revealed that the Upper Cretaceous oil shales were deposited in a shallow-water carbonate shelf. Oyster bioherms acted as physical barriers that reduced the water circulation with the open shelf, thereby causing anoxic conditions. The Eocene oil shales also accumulated on a shallow-water carbonate shelf. In this case, however, synsedimentary tectonics caused subsiding grabens and half grabens, which in turn gave way to anoxic conditions. Both deposition and richness of the Jordanian oil shales were affected by regional sea-level fluctuations and global climatic changes.

John Michael Hayes, Professor of chemistry and geology for 26 years at Indiana University (Bloomington) until 1996, then director of the National Ocean Sciences Accelerator Mass Spectrometry facility at Woods Hole Oceanographic Institution and adjunct professor at Harvard University until 2007, died peacefully at his home in Berkeley, California, on February 3rd, 2017.

As sedimentation progresses in the formation and evolution of a depositional geologic basin, the rock strata are subject to various stresses. With increasing lithostatic pressure, compressional forces act to compact the porous rock matrix, leading to overpressure buildup, changes in the fluid pore pressure and fluid flow. In the context of petroleum systems modeling, the present study concerns the geometry changes that a compacting basin experiences subject to deposition. The purpose is to track the positions of the rock facies interfaces as compaction occurs. To handle the challenge of potentially large geometry deformations, a new modeling concept is proposed that couples the pore pressure equation with a level set method to determine the movement of lithostratigraphic interfaces. The level set method propagates an interface according to a prescribed speed. The coupling term for the pore pressure and level-set equations consists of this speed function, which was derived from the compaction law. A first evaluation of the model concept is presented based on an implementation for one spatial dimension accounting for vertical effective stress. Thus, the propagation speed is determined by the sedimentation rate and the change in porosity. Both, the case of a linear compaction law and that of Athy’s exponential compaction law were studied for multiple rock facies, consisting of varying lithologies defined by initial porosities, permeabilities and grain densities. Isothermal conditions with a constant fluid density and viscosity were assumed. The accuracy of the implemented numerical solution for the case of a single stratigraphic unit with a linear compaction law was compared to the available analytical solution (Wangen 2010). The multi-facies setup and the nonlinear case were tested for plausibility. Reference: Wangen, A. (2010), Physical Principles of Sedimentary Basin Analysis, Cambridge University Press, 527 p.

Sediment petrographic studies combined with carbon and oxygen stable-isotope analyses are considered to be powerful tools in deciphering the depositional and diagenetic history of carbonate rocks. These studies have been found valuable for understanding the environmental controls and global changes of climate and oceanography. Two cores of Eocene bituminous marls (OS-22 and OS-23) from central Jordan with thicknesses of 222.4 m and 256.3 m, respectively, were logged. A total of 103 thin sections were analyzed for sediment petrographic investigations. Another 295 bulk rock samples from Core OS-23 were selected for stable-isotope analysis (δ13C, δ18O). The two cores show similar lithologic variations that correspond to third-order sea-level changes. The sediment petrographic study reveals the presence of six major microfacies that range from mudstones to grainstones. The distribution of these six types of microfacies in the two cores indicates an overall shallow-marine environment in an interior carbonate-platform setting. Within this environment, conditions fluctuated between open and restricted marine. The stratigraphic variability of the carbon-isotope data of Core OS-23 reflects a highly dynamic depositional system that exhibits a variable rate of organic matter accumulation in the sediments, which can be directly linked to the interaction between primary organic-matter burial and oxidative weathering of reworked organic matter. Within the overall diagenetically controlled δ18Ocarb profile an excursion is observed for a specifically enriched organic matter interval. This excursion is believed to coincide with the Middle Eocene Climatic Optimum (MECO), suggesting that next to seawater, porewaters were influenced by this event and making it the first record of this event in the region.

Reworked microfossils, common in Paleogene sediments in Jordan, are here used to reconstruct the depositional environment. The reworked taxa, which include both calcareous nannofossils and foraminifera of Cretaceous and Paleocene age, were found in Eocene oil shales. The potential provenance of the reworked material and the underlying processes of the reworking are discussed. We differentiate between a subaerial erosion of exposed hinterland strata and a submarine abrasion of sediments. A total of 73 smear slides have been prepared to identify calcareous nannofossils, another fifteen samples were analyzed for foraminifera. The allochthonous calcareous nannofossil and foraminifera taxa can be linked to a lithified source, which was eroded and transported with both calcitic lithic fragments and organic matter. Multiple factors controlling the transport of the reworked taxa during the time of deposition have been investigated for the Jordanian oil shales. Climate changes are thought to be the cause for changes in the abundance patterns and in the composition of the reworked taxa. The input of common autochthonous components during arid phases and more allochthonous sediment particles during humid periods filled the Eocene sink. A fall in relative sea level, perhaps in combination with increased storm activity, caused a transport of reworked material to deeper parts of the Azraq Hamza Sub-basin. The relative sea level changes in turn were related to syndepositional movements, redefining the shape of the Azraq Hamza Sub-basin and its internal fault-block architecture.

The study of trace fossils is widely used in facies interpretation. It provides a crucial tool for reconstructing depositional paleoenvironments when used in combination with other sedimentological and paleontological proxies. Here we present the first detailed study of Eocene trace fossils from Jordan. Two sections of Early to Middle Eocene age, with a total thickness of 478.7 m, from central Jordan were cored and investigated. The results of individually occurring (isolated) or co-occurring (combined) ichnofabrics and bioturbation levels, in combination with results from biostratigraphic and geochemical studies, were used for stratigraphic and paleoenvironmental reconstructions. The bioturbation index (BI) was used to classify the burrowing density versus the preservation of the original sedimentary structures. The two cores show highly variable grades of bioturbation with BI ranging from 0 to 6. Four ichnogenera were identified: Thalassinoides, Chondrites, Teichichnus and Zoophycos. Both the ichnofabrics and the variations of the BI suggest a shallow, highly dynamic depositional system with rapid changes of water depth and degree of bottom-water oxygenation.

The Upper Jurassic Draupne Formation in the North Viking Graben, North Sea, has been studied to identify lateral and vertical variations in source rock characteristics and their effect on the timing of petroleum generation. Fourteen source rock samples from the western flank of the graben and five from the eastern flank were analysed using Rock-Eval analysis, microscopy, open system pyrolysis gas chromatography and kinetic experiments.Two major organic facies with different petroleum generation characteristics were identified: a stratigraphically higher, thermally less stable facies, corresponding to a type II kerogen with HI (Hydrogen index) values of >350 mg HC/g TOC; and a stratigraphically lower, more stable type II/III facies with HI values Tmax 144 [deg]C) for the less stable facies and 153 [deg]C (geological Tmax 170 [deg]C) for the more stable. This corresponds to ~400 m difference in burial depth or delayed onset of petroleum generation by ~14 My. Based on a larger dataset from industry, the more stable facies may represent at least 40% of the Draupne Formation in our study areas. Our results imply that petroleum generation from the formation extends to greater depths than generally recognized and that the more stable Draupne organic facies also needs to be included in basin modelling studies to cover the full history of petroleum formation.

Introduction Unconventional resources have emerged as an important part of the world's energy supply. Engineering technological advances such as drilling horizontal clusters and completion solutions like hydraulic fracturing have contributed to the exponential growth of unconventional opportunities and their exploitation. Still a lot of headroom is left for a deep and improved understanding of the subsurface geologic controls on hydrocarbons' fluid movement and trapping characteristics. These characteristics are becoming paramount to de-risk the presence and extent of producible hydrocarbons in current and upcoming resource play opportunities. Unconventional Basin Simulator technology More specifically, it is the actual migration path and the compositional changes and alteration processes along it, which require an increase in focus. The latter seems to show a bigger impact than the initial question of whether a particular trap or reservoir was charged.

Abstract We integrate subsidence, thermal, and potential fields modelling in a single, unified workflow which reduces the propagation of uncertainty when building geological models of data-poor frontier areas such as deepwater continental passive margins. Subsidence analysis is combined with a model for the relationship between mantle melting and lithosphere stretching and resulting isostatic equilibrium to estimate crust thickness and type and the temperature and density of the crust and underlying mantle in the past and at present. The results can be compared to observations, including potential fields such as gravity in addition to well data if this is available. The integration of potential fields and thermal modelling is particularly important in frontier areas where well data is sparse to absent and conventional calibration data (T, VR) is not available to basin modellers. Our methods have been applied to a number of circum-Atlantic margins, allowing us to build basin scale play concepts and hydrocarbon maturation and charge models with greater confidence and guide exploration decision making. Introduction Basin subsidence on passive continental margins is a function of sediment-loading and of thermal subsidence (driven by crust and mantle density changes due to thinning and subsequent cooling). The stratigraphy of passive margins acts as a recorder of continental breakup processes. Integrated workflows and tools which model the breakup process can help reduce exploration risk associated with basin scale petroleum systems evolution and help identify appropriate global analogues. Integrated basin analysis workflow A wide-ranging collaboration between teams involved in research, software development and deployment, and exploration in both frontier and mature areas has enabled us to develop new basin analysis and modelling tools which integrate with, and leverage the strengths of, both proprietary software and the work of external research partners. The exploration context Integrated basin analysis is a vital component of basin to prospect screening of exploration acreage and reconnaissance hydrocarbon charge modelling on data-poor deepwater passive margins. It can contribute significantly to the identification and reduction of geological and stratigraphic risks prior to drilling and provides the framework for analysis of relevant well data, in both discoveries and dry holes, adjacent to the areas being screened. Building and constraining models for basin evolution We combine regional geological observations such as constraints from plate tectonic models, backstripping of the basin fill, analysis of physically plausible tectonic subsidence mechanisms, stratigraphic forward modelling and petroleum systems (i.e. hydrocarbon charge) analysis. Tighter integration of a number of workflows yields internally consistent, repeatable and reliable results which can be tested with a wide range of data. Well and outcrop data can be used to calibrate basin models, but in areas where limited (or no) data is available we can also validate models with gravity and magnetic data.

In this paper we investigate the presence of chaos in the system that underlies the Phanerozoic 87 Sr / 86 Sr isotope record of seawater carbonates by means of nonlinear time series analysis. The Fourier power spectrum estimation from the original time series together with the geological conjecture that the system is controlled only by a few (2 to 4) degrees of freedom point to an underlying chaotic system. The zero-order, correlation dimension and the largest Lyapunov exponent methods are employed to prove or to reject this assumption. Inherent problems of the data sets (non-equidistant and too sparse for a reliable application of these techniques) and the inability of the currently available methods to cope with them do not yet allow for a clear-cut decision.

Tree ring-width chronologies from the west coast of North America were obtained from on-line data archives, maintained by the National Oceanic and Atmospheric Administration (NOAA). Data covered the period 1650–1983, for trees sampled at 43 sites between Dawson Creek, British Columbia (55°N) and Yosemite Park, CA (37°N). These time series were analyzed using Fourier transformation methods. Spyglass Transform software allowed the resulting power spectra to be stacked and compared, based on characteristics such as topography and continentality, latitude and species ecological niche. Results suggested that several regular or quasi-regular cycles are occurring over various time periods. There are some similarities, though not an exact match, with El Nino periodicities noted by earlier authors. These patterns appear to be widespread, affecting trees at various elevations and distances from the coast, and from different species. A separate analysis of the oldest trees revealed sub-century cycles. In particular, the longer fluctuations at 50–65 years are consistent with recent findings on north Pacific climate by other authors. A Euclidean cluster analysis of individual years identified unusual year groupings between 1924–1946, a period associated with positive temperature anomalies and generally higher precipitation. These findings appear to be consistent with other basin-scale climate cycles, like the Southern Oscillation, and the recently-proposed Pacific Interdecadal Oscillation (PDO).

Stratigraphic collection of 263 belemnite rostra (guards) from Jurassic to Lower Cretaceous sediments in the Moscow area of Russia, northern Germany, England, New Zealand, and Morocco were analyzed to determine temporal variations in their delta 18 O and delta 13 C as a proxy for isotopic composition of surface seawater. Internal structures of the rostra were studied using cathodoluminescence and SEM techniques, their trace element (Fe, Mn, Mg, and Sr), and the stable carbon and oxygen isotope compositions. The average stratigraphic resolution is about 1 Ma. These samples represent a broad range of paleolatitudes and paleoceanographic settings, ranging from 42 degrees N to 82 degrees S, covering boreal to subtropical, brackish to open marine shelf paleoenvironments. The rostra originally contained domains enriched in organic matter that were later replaced by luminescent diagenetic calcite, thereby generating an impression of "seasonal growth rings." Diagenetic calcite accounts for up to 6.8 percent of the rostrum. The trace element content of the rostra range from 227 to 3935 ppm for Mg, 379 to 1514 ppm for Sr, and up to 305 and 3662 ppm for Mn and Fe, respectively. However, selective drilling of only primary calcitic domains resulted in 90 percent of all analyzed samples to fall within the range of trace element values typical for modern low Mg-calcite shells. The chemical and textural data suggest that the primary calcite of the rostra is well preserved, as is its isotopic signature. The delta 13 C and delta 18 O measurements define oscillating temporal bands, of about 3 to 4 per mil width, around more or less modern marine values of +2 and -1 per mil, respectively. Oxygen isotopes in the well preserved rostra most likely reflect temperature variations within a approximately 14+ or -8 degrees C range. The observed 3 to 4 per mil spread of values between contemporaneous specimens, which is comparable to the scatter of data reported for modern low-Mg calcitic brachiopod shells, probably reflects the diversity of local ecosystems, although some of the spread may be due to real short term temporal variations within single biozones. The delta 13 C values of the rostra define a band similar to that of the oxygen isotopes, and the temporal oscillations of both isotope curves are commonly in phase. The above dataset, complemented by the results of Jones, Jenkyns, and Hesselbo (1994) and Jones and others (1994), yields a composite delta 18 O and delta 13 C variations in belemnite guards for the entire Jurassic-Early Cretaceous interval. For delta 18 O, the oscillating band indicates that the most negative values occur at times of independently postulated global and/or regional anoxic events, such as those in the Toarcian and Kimmeridgian as well as the Aptian. These OAEs appear to be characterized by up to 10 degrees C higher seawater temperatures than the intervening background times. The delta 13 C record shows 13 C depletion for the Kimmeridgian event but enrichment for the other two, suggesting that the delta 13 C temporal oscillations and OAEs are not simply a reflection of surficial productivity due to operation of the biological pump, but rather of changing oceanic circulation patterns due to variations in latitudinal surface temperature gradients.

A new generation 87Sr/86Sr isotope curve for the Phanerozoic seawater, based on a compilation of 3635 stratigraphically well defined and well preserved skeletal components, results in a substantially narrower band, with some discrepancies, if compared to the `curve' of Burke et al. (1982) , which is based mostly on whole-rock samples. The results obtained from low-Mg calcite shells (foraminifers, belemnites, brachiopods and oysters) are mostly superior to those from phosphatic skeletal components, such as conodonts, even if the latter are exceptionally well preserved (CAI ≤1.5). At this stage, the Phanerozoic data set based on fossils is patchy for the Cambrian, Upper Ordovician–Lower Devonian and Upper Carboniferous–Triassic intervals. The major practical constraint that precludes delineation of an unequivocal Sr isotope curve for the Phanerozoic seawater is the uncertainty in the assignment of absolute ages to the samples. As a result the curve is in reality a band. This is a reflection of the limitations of biostratigraphy and geochronology that are inherited by any derivative correlation and dating technique, including isotope stratigraphy. It is therefore unlikely that, in the near future, the Sr isotope stratigraphy will surpass the resolution capability of biostratigraphy as a global correlation tool. On the other hand, if complemented by lithostratigraphy, it is potentially a valuable tool for correlation of sequences on intrabasinal and regional scales. Taking into account the above limitations, careful consideration must be given to assignment of higher order isotope peaks to specific `events' within a biozone and to the use of such events as a global correlation tool.

A compilation of over 2000 measurements of 18O and 13C on Phanerozoic low-Mg calcite shells, such as brachiopods, belemnites and oysters, delineates secular 18O/16O and 13C/12C variations that are similar to those previously described for whole rocks. The trend for the δ18O suggests about ∼5±2‰ enrichment from the Cambrian to today. In contrast, the δ13C rise during the Paleozoic is followed by its decline in the Mesozoic and Cenozoic. Optical (textural) and chemical criteria suggest that the interior “secondary” layer of the brachiopod shells, the material that carries these signals, is well preserved in many samples and the extracted secular isotopic trends are therefore a primary feature of the geologic record. The similarity of the δ18O/δ13C isotope patterns in ancient and modern brachiopods also supports such an interpretation. In our view, the 18O enrichment in progressively younger samples is principally, although not exclusively, a reflection of the evolving 18O/16O composition of seawater. If so, a delineation of this trend may ultimately result in development of a valuable paleoclimatic and paleoceanographic tracer for the Phanerozoic.

North Rhine-Westphalia, the most industrialized and densely populated state of Germany, is drained by six major tributaries of the Rhine: the Sieg, Wupper, Ruhr, Erft, Emscher, and Lippe. The first four drain predominantly catchments with Phanerozoic siliciclastic rocks, while the latter two dewater Cretaceous carbonate basins. Together, the rivers account for {approximately}11 percent of the Rhine water, and they reflect various stages of pollution, from a moderately polluted Sieg and Ruhr to the heavily damaged Emscher. The {delta}{sup 18}O H{sub 2}O of -8.5{+-}1.5 permil SMOW suggests that summer recharge into local aquifers is the main source of water in these rivers. Down-stream, the water becomes enriched in {sup 18}O, by {approximately}2 permil, due to low altitude precipitation and because of evaporation, particularly in artificial lakes. However, thermal fractionation, when water is utilized for cooling in power stations and smelters, also contributes to this trend. State-wide, and down-stream within rivers, the increasing pollution levels are characterized by rising salt concentrations (from normal riverine values up to a third of seawater), by up to two orders of magnitude CO{sub 2} overpressures, oxygen depletion, and enhanced nutrient concentrations. The {delta}{sup 13}C{sub DIC} demonstrate that microbial respiration of C{sub org} in soil/groundwater systems accountsmore » for about 50 to 100 percent of the entire DIC, with the higher values typical of more polluted ecosystems. Evasion of gaseous CO{sub 2} into the atmosphere and microbial nitrification are the most important processes for the riverine aquatic cycles of carbon and nitrogen, resulting in more advanced dissipation of CO{sub 2} and NH{sub 4}{sup +} in the less polluted ecosystems. Denitrification may fuel generation of some {open_quotes}excess{close_quotes} CO{sub 2} only in the highly polluted ecosystems, such as the Emscher. 58 refs., 15 figs., 1 tab.« less

We report a new oil and gas prospecting technique based on measurements of sub-part-per-billion ethane concentration in the atmosphere and local wind data. The sensitivity of our sensor enables detection, from a range of several km, of the naturally occurring ethane seepages that accompany hydrocarbon reservoirs. Using the concentration and wind data, the gas dispersion process is inverted to provide maps of surface ethane flux over several hundred km(2). Within a desert environment, we demonstrate the technique is capable of locating a controlled release and corresponds with the results from a geochemical soil sampling survey conducted over the same oil field.

A total of 2128 calcitic and phosphatic shells, mainly brachiopods with some conodonts and belemnites, were measured for their δ18O, δ13C and 87Sr/86Sr values. The dataset covers the Cambrian to Cretaceous time interval. Where possible, these samples were collected at high temporal resolution, up to 0.7 Ma (one biozone), from the stratotype sections of all continents but Antarctica and from many sedimentary basins. Paleogeographically, the samples are mostly from paleotropical domains. The scanning electron microscopy (SEM), petrography, cathodoluminescence and trace element results of the studied calcitic shells and the conodont alteration index (CAI) data of the phosphatic shells are consistent with an excellent preservation of the ultrastructure of the analyzed material. These datasets are complemented by extensive literature compilations of Phanerozoic low-Mg calcitic, aragonitic and phosphatic isotope data for analogous skeletons. The oxygen isotope signal exhibits a long-term increase of δ18O from a mean value of about −8‰ (PDB) in the Cambrian to a present mean value of about 0‰ (PDB). Superimposed on the general trend are shorter-term oscillations with their apexes coincident with cold episodes and glaciations. The carbon isotope signal shows a similar climb during the Paleozoic, an inflexion in the Permian, followed by an abrupt drop and subsequent fluctuations around the modern value. The 87Sr/86Sr ratios differ from the earlier published curves in their greater detail and in less dispersion of the data. The means of the observed isotope signals for 87Sr/86Sr, δ18O, δ13C and the less complete δ34S (sulfate) are strongly interrelated at any geologically reasonable (1 to 40 Ma) time resolution. All correlations are valid at the 95% level of confidence, with the most valid at the 99% level. Factor analysis indicates that the 87Sr/86Sr, δ18O, δ13C and δ34S isotope systems are driven by three factors. The first factor links oxygen and strontium isotopic evolution, the second 87Sr/86Sr and δ34S, and the third one the δ13C and δ34S. These three factors explain up to 79% of the total variance. We tentatively identify the first two factors as tectonic, and the third one as a (biologically mediated) redox linkage of the sulfur and carbon cycles. On geological timescales (≥1 Ma), we are therefore dealing with a unified exogenic (litho-, hydro-, atmo-, biosphere) system driven by tectonics via its control of (bio)geochemical cycles.

Cretaceous and Paleogene marls, rich in total organic carbon, are widespread throughout Jordan and adjoining areas. Based on planktonic foraminifera these oil shales have been assigned a late Campanian–Paleocene age in previous studies. For the current analysis a total of 283 smear slides from five wells in central Jordan have been investigated for calcareous nannofossil biostratigraphy. Findings suggest a much more differentiated age model of the oil shales than previously proposed. The oil shales studied contain abundant calcareous nannofossil taxa of Eocene age along with varying abundances of Maastrichtian and Paleocene taxa. The encountered marker species Rhomboaster cuspis, Tribrachiatus bramlettei, Tribrachiatus orthostylus, Discoaster lodoensis, Coccolithus crassus, Discoaster sublodoensis, Nannotetrina quadrata, Reticulofenestra umbilicus and Chiasmolithus solitus, indicate an Early to Middle Eocene age, while the presence of Maastrichtian and Paleocene forms suggests major reworking. The presence of Cretaceous taxa reflects either subaerial erosive input from the hinterland or submarine reworking of Cretaceous strata within the basin. The highly variable amount of reworked material and associated deposition rates in the basin may represent changes in the tectonic setting during the Eocene. We propose that the high abundances of Cretaceous and Paleocene taxa reflect an increase in accommodation space by active graben flank movements. A dominance of Eocene taxa, on the other hand, indicates either periods of little accommodation space due to graben infill or inversion-type movements of the graben itself. In any case, the youngest Eocene and autochthonous taxa represent shallower or low topography graben phases.