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Choanoflagellates are microeukaryotes that inhabit freshwater and marine environments and have long been regarded as the closest living relatives of Metazoa. Knowledge on the evolution of choanoflagellates is key for the understanding of the ancestry of animals, and although molecular clock evidence suggests the appearance of choanoflagellates by late Neoproterozoic, no specimens of choanoflagellates are known to occur in the fossil record. Here the first putative occurrence of choanoflagellates in sediments from the Cretaceous (Cenomanian–Turonian) is described by means of several cutting-edge petrographic techniques, and a discussion of its paleoenvironmental significance is performed. Furthermore, their placement in the organic matter classification systems is argued, with a placement in the Zoomorph Subgroup (Palynomorph Group) of the dispersed organic matter classification system being proposed. Regarding the ICCP System 1994, incorporation of choanoflagellates is, at a first glance, straightforward within the liptinite group, but the definition of a new maceral may be necessary to accommodate the genetic origin of these organisms. While modern choanoflagellates may bring light to the cellular foundations of animal origins, this discovery may provide an older term of comparison to their extant specimens and provide guidelines for possible identification of these organic components in other locations and ages throughout the geological record. [ABSTRACT FROM AUTHOR]

The Aptian-Albian sedimentary record of the Parnaíba Basin (NE Brazil), represented by the Codó and Itapecuru formations, is characterized by near-shore, shallow marine, and fluvio-lacustrine clastic sediments deposited in a large shallow sag basin that developed during the breakup of northwestern Gondwana associated with the early opening stages of the South Atlantic. This study aims to precisely characterize the nature, variability, paleoenvironmental significance and preservation conditions of the organic matter of the Aptian-Albian succession of the 2-TV-1-MA borehole (270 m). With these premises, organic petrographic and geochemical techniques were applied for the definition of the organic facies, allowing a better understanding of the Parnaíba Basin evolution during the Aptian-Albian interval. The 2-TV-1-MA borehole presents, at the base, a lacustrine system, with a high contribution of continental components deposited in a high energy, oxic environment, with incipient marine influence. This is intercalated by periods of restriction, with deposition occurring in a dysoxic-anoxic, low energy environment, with high contribution of higher plants. To the top, a relative decrease in the water-column leads to an increase in restriction, the emplacement of a stratified water-column, and the development of microbial mats. This is topped by a return to a high energy, oxic environment, with marine influence, and dominance of higher plants organic components. • Four depositional systems have been proposed for the 2-TV-1-MA well core. • A first marine influence in the initial stages of deposition of the Codó Fm. • Organic-rich levels with terrestrially-derived AOM coeval with OAE 1b. [ABSTRACT FROM AUTHOR]

The early Toarcian is marked worldwide by major environmental changes that resulted in organic-rich black shale deposition, the Toarcian Oceanic Anoxic Event (T-OAE). This organic-rich sedimentation is particularly recorded in the Grands Causses (GCB) and Quercy (QB) basins. The main objectives of this study are the characterization, through organic petrology and geochemistry techniques, of the organic matter (OM) of the late Pliensbachian – early Toarcian sedimentary successions of these basins and the definition of the organic facies, assessing their implications in the evolution of depositional paleoenvironments. In the GCB sedimentation occurred, during the late Pliensbachian, in a well oxygenated water body (Total Organic Carbon - TOC 0.6 wt.% and low Amorphous Organic Matter - AOM) proximal to the terrestrial source area (high terrestrial contribution) with marine influence. In the lattermost Pliensbachian a shallowing of the water column is observed with decrease of marine influence and separation from the terrestrial source area (TOC 0.9 wt.%, AOM and zooclasts co-dominate) under an arid climate ( Classopollis ssp.). From the Tenuicostatum to early Serpentinum chronozones a restricted and stagnated environment (TOC 5.7 wt.%, AOM dominates) is implemented. From middle to late Serpentinum Chronozone the reestablishment of the oxygen levels (decrease in TOC and AOM) takes place, as well as paleoceanographic circulation patterns. In the QB, the late Pliensbachian to earliest Toarcian is characterized by low TOC (0.2 wt.%) with sedimentation occurring in a shallow oxygenated proximal water body (amorphous Hydrozoans dominate) separated from the terrestrial source area with arid climate ( Classopollis ssp.), and with episodes of emersion. From the Semicelatum Subchronozone to Serpentinum Chronozone the development of dysoxic to anoxic conditions (TOC 4.2 wt.%) takes place, associated with water column stratification and more effective non-carbonate sedimentation, and with an increase in water level. For the lattermost Serpentinum Chronozone shallowing of a more oxidizing water body, with some oxygen depletion still present is proposed. The differences in these paleoenvironmental depositional contexts further demonstrate that, although the T-OAE has a global character, local control mechanisms in these basins play a pivotal role. Furthermore, the first occurrence of Hydrozoans, namely its free-swimming medusoid forms, is described in organopalynological preparations of sediments from the Pliensbachian–Toarcian and their first paleoenvironmental application in a palynofacies based study is made. [ABSTRACT FROM AUTHOR]

Laser micropyrolysis provides important molecular data on organic fossils such as coals, source rocks, oil shales and kerogen. In our laboratory, the micropyrolysis system refers to a laser and an optical device; a sample chamber and cold trap; and a gas chromatography coupled with mass spectrometer triple quadripole (LmPy-GCMS) to separate and detail the composition of molecular pyrolysis products. The goal of this work was to use laser micropyrolysis to acknowledge the chemical structure of Botryococcus braunni and Gloeocapsomorpha prisca microfossils. The obtained results showed that isolated Botryococcus to have predominance of alkene > alkanes > diene hydrocarbons from C8 to C20 as well as the absence of botryococcenes and methylated squalenes, which chemical composition was similar with race A and S, as it has been described in the literature. Laser pyrolysis of G . prisca showed the carbon number distribution of n -alkanes and alkenes similar to those observed in the pyrolysates from B . braunni however, with low amount of C20 + n -alkanes. It was also noticed a contribution of oxygenated compounds in Kukersite pyrolysis products. Therefore, the collected data from laser experiments can complement the information obtained from bitumen analysis and showed no correlation can be made between Botryococcus braunii and Gloeocapsomorpha Prisca . Also, the use of LmPy-GCMS can improve our studies in chemical characterization of small components in heterogeneous material, as well as an identification of specific biomarkers in isolated microfossils. [ABSTRACT FROM AUTHOR]

The Middle Jurassic to Cretaceous sedimentary record in the Lusitanian Basin (Portugal) reveals the presence of disseminated solid bitumen. The present work is focused on the petrographic characteristics of solid bitumen identified in the Freixial-1 and Benfeito-1 boreholes (Arruda sub-basin, Lusitanian Basin) that display different thermal maturities. Microscopy techniques (reflected and transmitted white light, incident blue light and SEM) and organic geochemistry analyses (total organic carbon, total sulfur and insoluble residue) were used to study these samples. From the results obtained by optical microscopy (fluorescence and reflectance) it was possible to distinguish three types of solid bitumen. They were labeled as solid bitumen A, present in all the samples, solid bitumen B and solid bitumen C, these ones observed in some of them. They correspond to allochthonous (migrated) bitumens. In blue incident light, some bitumen do not show fluorescence while others reveal fluorescence that range from yellow (solid bitumen B) to dark brown (solid bitumen A). All bitumens are optically isotropic. Bitumen reflectance varies between 0.70 and 2.60% R r , and the vitrinite reflectance ranges from 1.11 to 1.48% R r . Based on the % R r values, the solid bitumen identified in these samples are classified as impsonite (epi- and cata-) or pyrobitumen. No relation can be established with confidence for the reflectance of bitumens with the reflectance of vitrinite. [ABSTRACT FROM AUTHOR]

The Middle Jurassic to Cretaceous sedimentary record in the Lusitanian Basin (Portugal) reveals the presence of disseminated solid bitumen. The present work is focused on the petrographic characteristics of solid bitumen identified in the Freixial-1 and Benfeito-1 boreholes (Arruda sub-basin, Lusitanian Basin) that display different thermal maturities. Microscopy techniques (reflected and transmitted white light, incident blue light and SEM) and organic geochemistry analyses (total organic carbon, total sulfur and insoluble residue) were used to study these samples. From the results obtained by optical microscopy (fluorescence and reflectance) it was possible to distinguish three types of solid bitumen. They were labeled as solid bitumen A, present in all the samples, solid bitumen B and solid bitumen C, these ones observed in some of them. They correspond to allochthonous (migrated) bitumens. In blue incident light, some bitumen do not show fluorescence while others reveal fluorescence that range from yellow (solid bitumen B) to dark brown (solid bitumen A). All bitumens are optically isotropic. Bitumen reflectance varies between 0.70 and 2.60% R r , and the vitrinite reflectance ranges from 1.11 to 1.48% R r . Based on the % R r values, the solid bitumen identified in these samples are classified as impsonite (epi- and cata-) or pyrobitumen. No relation can be established with confidence for the reflectance of bitumens with the reflectance of vitrinite. [ABSTRACT FROM AUTHOR]

Abstract: Studies of the Mesozoic and Cenozoic sequence crossed by the Barreiro-4 borehole provide an improved understanding of the organic matter deposited in the Lower Tagus sub-basin (Lusitanian Basin, Portugal) and the implications for the potential source rock and depositional environment. This study focused on 43 samples (Middle Jurassic to Neogene) that were subjected to palynofacies and organic geochemistry analyses (Total Organic Carbon, Rock-Eval pyrolysis and molecular biomarker analysis). The palynofacies data indicate that the sequence contains mainly phytoclasts (non-opaque phytoclasts). However, the Middle Jurassic samples are dominated by Amorphous Organic Matter (AOM). Continental and/or marine palynomorphs are present in all the samples. The Cretaceous samples are characterized by small amounts of kerogen that have high contents of solid bitumen. The Total Organic Carbon (TOC) content is generally less than 1 wt.%. The Rock-Eval S1 and S2 parameters vary from 0.01 to 3.50 mgHC/g rock and 0.15 to 34.03 mgHC/g rock, respectively, with the highest values corresponding to the Cretaceous samples. The hydrogen index (HI) and oxygen index (OI) values range from 35 to 552 mgHC/g TOC and 4 to 180 mgHC/g TOC, respectively. The T max values range from 416 to 437 °C. The biomarker analysis showed that n-alkanes with 15–30 carbon atoms are present and usually have a unimodal distribution with a predominance of low to medium molecular weight compounds. The CPI values range between 0.63 and 3.65, and the pristane/phytane ratios vary between 0.48 and 1.64, indicating alternation of oxic–anoxic conditions along the sequence. The distribution of terpanes shows small amounts of tricyclic and tetracyclic terpanes in most of the samples (except for some Cretaceous samples) and a predominance of pentacyclic terpanes. The amount of 17α (H),22,29,30-trisnorhopane (Tm) usually exceeds the amount of 18α (H),22,29,30-trinorneohopane (Ts). The 20S/(20S + 20R) and αββ/(ααα + αββ) ratios of the C29 steranes generally have values below the range of equilibrium, indicating an immature stage of the OM. [Copyright &y& Elsevier]

The Middle-Upper Jurassic transition is a geodynamic benchmark in the evolutionary history of several peri-Atlantic basins. Contrary to the vast Tethyan and peri-Tethyan areas, in the Lusitanian Basin (Portugal), this interval corresponds to a major basin-wide disconformity preceded by a complex forced regression that induced sharp facies variations across the depositional systems. The Middle Jurassic units below are fully marine, whereas the Upper Jurassic sediments (Lower?-Middle Oxfordian), correspond to freshwater/brackish lacustrine, grading into punctuated brackish-restricted lagoonal and shallow-marine paleoenvironments. This study presents total organic carbon and palynofacies data of 34 samples (total analyzed thickness about 85 m) collected from three key sections encompassing the Middle-Upper Jurassic transition in the central-northern sector of the Lusitanian Basin. The palynofacies of the analyzed part of Middle Jurassic units (Cabo Mondego Formation) are characteristic of marine environments at their base, evidencing upwards a regressive trend of the depositional systems. Total organic carbon content is generally low, reaching up to 1.94 wt%. The Upper Jurassic Cabaços Formation presents kerogen assemblages mostly of continental origin, although punctuated by minor intervals of marine influence. Total organic carbon content is more variable, reaching up to 30.56 wt%. Intraclasts of re-deposited fragments of microbial mats were found incorporated in the kerogen assemblages, which point to highly dynamic erosional and depositional processes. Diversity of Botryococcus sp. occurrences was confirmed as an indicator of the degree of paleoenvironmental stability. The vertical distribution and comparison of the kerogen assemblages of the different sections indicate major changes of these parameters among relatively close settings and along narrow vertical intervals, attesting to the high sedimentary dynamics observed in the Lusitanian Basin. [ABSTRACT FROM AUTHOR]

Abstract: A high-resolution study (n=66) was conducted on Late Permian coal measures of the Bowen Basin, Australia, to observe palynofacies changes during peat accumulation over time. Palynofacies were determined using polytopic vector analysis (PVA) to derive end members with variable compositions that reflected fine scale environmental changes, within and between seams, of the Kaloola Member. Palynofacies reflect a three-stage succession within the palaeo- peat-forming environments from stable, anoxic conditions at the base, progressing to variable, oxic conditions toward the top of each seam. In cases where a seam was capped by tuff, rather than siliciclastic sediment, anoxic conditions similar to the bottom of each seam occurred. The results corroborate previous interpretations of palaeofloral communities and provide a new palynofacies model that integrates environmental progression within the coal seams in the Late Permian coal measures of the Bowen Basin. A complementary study of palynological assemblages recognised a shift from Dulhuntyspora sp., to Protohaploxypinus sp. in the lower Kaloola Member, indicating a change in pollen/spore source. Associations between dispersed palynomorphs and coal phyterals of parent flora remain tenuous beyond class rank, due to poor preservation and taxonomic bias inherent within the sample space. This is the first such palynofacies study to be conducted in the Bowen–Sydney–Gunnedah basin complex, thus opening the way for future work examining regional changes in palynofacies, expressed in both coal and siliciclastic sediments. [Copyright &y& Elsevier]

Organic petrology is an important tool used to characterize dispersed organic matter (DOM) in sediments and sedimentary rocks, and to assess its thermal maturity. This study was carried out on 33 cutting samples (Middle-Upper Jurassic) from the Ramalhal-1 well to characterize the particulate organic matter and to evaluate its thermal maturity. The samples were submitted to optical petrography analysis (reflected white and blue incident lights) and the mean random reflectance was measured. Microscopic observations revealed a low DOM content, characterized by the predominance of macerals of the inertinite group (including charcoal), followed by solid bitumen. Huminite/vitrinite is usually small in size and quantity. Liptinite macerals were also present, represented by sporinite, cutinite, liptodetrinite and rare bituminite. A type III-IV kerogen was defined for the Ramalhal-1 sequence. Huminite/vitrinite mean random reflectance varied between 0.38% and 0.75%, pointing to an immature-to-mature stage of the organic matter. Multi-populations of solid bitumen occurred in almost all the samples, filling voids and fractures in the inorganic materials (mainly carbonates). The bitumen populations were quite heterogeneous, concerning both the optical characteristics and distribution, displaying different thermal maturities. No relationship between vitrinite and bitumen reflectance was established, indicating that these bitumens were not generated in situ. [ABSTRACT FROM AUTHOR]

The study across the Pliensbachian–Toarcian boundary sedimentary record in the Bizanet section of the Pyrenean Basin (southern France) revealed the presence of solid bitumen. This secondary organic matter was characterized using petrographic (transmitted and reflected white lights, incident blue light, and scanning electron microscopy) and geochemical (total organic carbon, total sulfur, and insoluble residue) techniques. The spore coloration index (SCI) was also determined. With the characterization of the optical properties and reflectance of the solid bitumen, it was possible to distinguish four different families (A–D) that display a wide range of reflectance values, from 0.21% to 2.64% BRr, i.e., from glance pitch to meso-impsonite. SCI values were higher than 9–9.5 (%Req > 1.50%). The comparison between the equivalent vitrinite reflectance values of the solid bitumen and SCI showed that this index and the solid bitumen D values are concordant, indicating that solid bitumen D can be considered an indigenous bitumen. The other three families of solid bitumen (A–C) are considered as having migrated. The laterally equivalent Pont de Suert section (South Pyrenean Zone) displays no trace of solid bitumen which points to the important role of the morphotectonic context of the Bizanet section in the migration of these hydrocarbons, namely, the presence of a major thrust fault in the eastern Corbières close to the section's location. [ABSTRACT FROM AUTHOR]

Abstract: A Middle–Upper Jurassic sedimentary succession has been cut by the Ramalhal-1 borehole in the Bombarral sub-basin (Lusitanian Basin, Portugal). The succession comprises the Brenha, Montejunto, Abadia and Lourinhã Formations, which are composed of limestones, marls, sandstones and clays. The main objective of this study was to characterize the organic matter using palynofacies and geochemical analyses to determine the depositional paleoenvironments and the hydrocarbon generation potential. The Total Organic Carbon content is generally less than 1wt.% but reaches 4.1wt.% in one sample, due to the presence of perhydrous coal. The Rock-Eval pyrolysis results reveal lower values HI, usually nether to 100mgHC/gTOC, showing that the studied samples have type III kerogen and a low potential for oil generation. The Tmax values (varies between 319 and 443°C) and biomarker data obtained for these samples indicate a maturation ranging between immature and, eventually, mature. The palynofacies data indicate predominance of the Phytoclast group (>80%), with different degradation degrees and a modest contribution of Palynomorph group, especially sporomorphs, and the Amorphous Organic Matter (AOM) group. Solid bitumen was observed in some samples from the Montejunto and Brenha Formations. Determining the relative percentages of the kerogen groups allowed for the identification of seven intervals that established variations in the depositional environment. [Copyright &y& Elsevier]

Data on lipids, carbohydrates and proteins of the most expressive black shale (s.l.) intervals of the Early--Late Pliensbachian (Early Jurassic, ˜187 Ma) organic-rich hemipelagic series of the Lusitanian Basin (Portugal) were determined using a method that has been successfully applied over the last two decades in the characterization of biomass and very immature sediments. The goal of this paper is to test the applicability of these techniques to the ancient geological record. To our knowledge, this is the first time that this type of biogeochemical data from sedimentary series older than Oligocene is reported and tentatively used for palaeoenvironmental/diagenetic inferences. Carbohydrates and proteins are present in low concentrations, reaching up to 385.13 and 451.13 µg/g rock, respectively. The main variations are observed in the lipid contents, ranging from 197.67 to 8446.36 µg/g rock. The samples with the highest amounts of lipids seem to correlate with low [O2] time intervals determined by independent data, such as organic petrography, micropalaeontology and sedimentology. This was probably related with selective lipid preservation under oxygen and hydrogen sulfide-rich depleted environments. The good overall match between the determined lipid contents and specific depositional/early diagenetical conditions seem to favor the idea that the easy to perform and inexpensive method applied here has the potential to add useful information to the study of ancient organic-rich carbonate sedimentary series. [ABSTRACT FROM AUTHOR]

Abstract: In order to place information from palynofacies variations in a sequence stratigraphic context, palynofacies analyses for wells GTP-17-SE and GTP-24-SE from the Sergipe Basin, was integrated with sequence stratigraphy. Previous works assigned the succession to two second-order sequences, K50 and K60, the last being subdivided into systems tracts KM1 and KM2 (third-order sequences). By combining lithofacies data and gamma-ray logs from the studied wells with palynofacies and paleoecological data, the succession was subdivided into third-order sequences and correlated with the integrated sequence stratigraphic framework. The K50 sequence shows a slightly transgressive upward trend. The sequence boundaries of K50 are marked by major peaks in abundance of phytoplankton and amorphous organic matter and in the gamma-ray. KM1 sequence starts below of the boundary between Muribeca and Riachuelo Formations. This sequence was subdivided into three parasequences. The first transgressive systems tract is supported by a marked increase in Palynological Marine Index and amorphous organic matter values, and the phytoclast relative abundance shows a progressive decrease. The upper boundaries are marked by maximum flooding surface characterized by high abundances of dinoflagellate cysts. The boundaries are also marked by an abrupt decrease of phytoclasts, which is best observed in well GTP-24-SE. The highstand systems tract is characterized by an increase in amount of phytoclast particles, a clear decrease in amorphous organic matter percentage values and moderate values that tend to increase upwards of the Palynological Marine Index. The upper boundary of this sequence is marked by a peak of dinoflagellate cysts indicating the transgressive surface. In well GTP-24-SE, the boundary is placed at the base of an abrupt lithological change, from calcilutites to dark shales. The second transgressive systems tract is based on a marked increase in Palynological Marine Index and amorphous organic matter percentage values, together with the clear decrease in phytoclast particles. These are observed clearly in well GTP-24-SE, especially the decrease of phytoclasts. The top of these parasequences is distinguished on the basis of the peaks of Palynological Marine Index indicating the maximum flooding surface. In well GTP-24-SE, the lowest abundances of the phytoclast group are recorded at the maximum flooding surface. The KM2 sequence interpreted previously as a highstand systems tract is confirmed herein, on the basis of palynofacies. [Copyright &y& Elsevier]

Abstract: Palynofacies analyses were carried out on 272 core samples from two wells (GTP-17-SE and GTP-24-SE) in the Sergipe Basin, with the aim of reconstructing the paleoenvironments of the upper Aptian–middle Albian. For the palynofacies analysis the kerogen categories were counted and subjected to cluster analyses. For detailed environmental analysis, kerogen distribution trends and parameters were applied, based on percentages of kerogen categories. Total organic carbon analysis was also used. The stratigraphic distribution of palynofacies associations that defined eight palynofacies units in well GTP-17-SE and ten in well GTP-24- SE reflects a continuous terrestrial influx throughout the succession. Amorphous organic matter (AOM) and palynomorph groups show moderate to high percentages, especially in well GTP-24-SE. The increase in relative abundance of these groups suggests that a long-term a transgression and/or a decreasing terrestrial influx occurred in the area. From the bottom to top six depositional environments were identified in wells GTP-17-SE and GTP-24, respectively, and they reflect the progressive increase in marine influence as the basin evolved. Brackish lagoon conditions changed to more open marine conditions as sea level changed during the separation of South America from Africa. [Copyright &y& Elsevier]

The Cenomanian—Turonian boundary is marked by worldwide paleoenvironmental and paleoceanographical changes that are associated with a perturbation of the global carbon cycle and black shale deposition, called the Oceanic Anoxic Event 2 (OAE2). The objective of this study is to precisely characterize the nature of the organic matter, its variability, paleoenvironmental significance and the preservation conditions of two areas located along the northwest African Shelf where large-scale organic carbon burial contributed significantly to the global carbon burial associated with OAE2. With these premises, an organic petrographic and geochemical approach to the Cenomanian—Turonian record of the Moroccan Atlantic coast allowed the definition of the variability of the organic facies and the paleoenvironmental characterization of the upper Cenomanian—lower Turonian sediments of the Agadir section (Agadir Basin) and of the lower Turonian record of the Amma Fatma section (Tarfaya Basin). At Agadir, the marine microplankton dominated assemblages, with variable degree of amorphization, allowed the characterization of a transgressive-regressive cycle during the upper Cenomanian followed, during the lower Turonian, by a drowning event with establishment of a deep platform environment (under reducing conditions, increase in EFU, EFV, EFMo). The base of the succession (base of W. archaeocretacea biozone) and the top of the upper Cenomanian are characterized by two sea-level lowstands, and a high energy oxic environment, that culminate in emersion surfaces (high EFMn and low organic matter preservation). The organic facies in the lower Turonian of Amma Fatma is largely dominated by bacterial material (probably derived from sulfur bacteria), indicating an outer shelf setting, with some degree of restriction, under euxinic conditions (high EFMo) and high primary productivity (high EFCu, EFNi, EFZn). Differences in terms of the redox conditions between the two basins during the lower Turonian were determined, with anoxia prevailing at Agadir, while euxinic conditions are established at Tarfaya. These are explained by different oceanic circulation patterns, with the mixing of Tethyan waters at Agadir. High primary productivity is recorded at both locations, possibly promoted by the occurrence of upwelling currents. This study further corroborates a delay in the anoxia in Agadir, that during the isotopic excursion of OAE2 only reaches slight dysoxia (upper Cenomanian), and the maintenance of reducing conditions in Tarfaya post-OAE2. • Paleoenvironmental conditions during Cenomanian—Turonian at Agadir and Tarfaya. • Bacterial material in the organic facies of the Amma Fatma section. • Different redox conditions in the Agadir and Tarfaya basins during the lower Turonian. • Global vs local control mechanisms on the OAE2 organic record are highlighted. • Corroborates delay of anoxia in shallow water marginal environments during OAE2. [ABSTRACT FROM AUTHOR]

The Cenomanian-Turonian boundary is marked by global sea-level highstands and one of the warmest periods of the Mesozoic, with high p CO 2 levels linked to a massive magmatic episode. This is associated with the establishment of a worldwide marine anoxia, the deposition of organic-rich facies and disturbances of the global carbon cycle, the so-called Oceanic Anoxic Event 2 (OAE2). The Pont d'Issole section's (Subalpine Basin, SE France) sedimentary succession represents the reference record of OAE2 in the Tethyan domain, although its organic fraction is extremely poorly studied. Therefore, the main objectives of this study are the characterization of the Pont d'Issole section's organic matter (OM) for paleoenvironmental interpretation and the assessment of the OM thermal maturity using organic petrology and organic geochemistry techniques. The organic record characterizes a shallowing-up marine system with varying redox and restriction conditions, associated with periods of stratified oxygen regimen. It displays the presence of two OM enrichment episodes with different paleoenvironmental and geodynamic contexts. The first OM enrichment episode (Unit Th1) is thought to be associated with the global mechanisms that trigger OAE2 and is characterized by a palynofacies association co-dominated by amorphous OM and marine microplankton, reflecting a context of high sea-level. This is followed by the Plenus Cold Event (Unit Th2), characterized by a decrease in amorphous OM and increase in marine microplankton, representing a reoxygenation associated with an increase in water level, and an apparent decrease in temperature (disappearance of Classopollis sp.). The second OM enrichment episode (Unit Th3 and base of Unit Th4) is characterized by an association dominated by amorphous OM, the occurrence of freshwater microplankton, and the development of a restricted environment with low sea level. These depositional conditions are thought to be connected to the beginning phases of basin closure, promoted by the regional tectonic framework (compressive trend between Africa and Europe). The molecular fraction showed the presence of unsaturated compounds, monoaromatic steranes, monoaromatic anthrasteroids and the biological ββ hopanes, indicating a low thermal evolution for the OM. This is corroborated by biomarkers ratios and organic petrographic data, namely vitrinite reflectance (0.29% R r). The presence of Paleozoic reworked OM in the samples was also identified presenting a more complex thermal history than the Cretaceous OM. This OM is possibly related to the subaerial erosion of Hercynian Massifs. • Depositional paleoenvironmental conditions during CTB at Pont d'Issole section. • Global vs local control mechanisms on the OAE2 organic record are highlighted. • Identification of the presence of Paleozoic reworked organic matter at Pont d'Issole. [ABSTRACT FROM AUTHOR]

Highlights • Petroleomics of crude oils recovered from the Mero Field, Santos Basin, Brazil. • The samples were generated under a thermal condition related to the peak of the oil window (0.7–0.9%Ro). • The samples were generated by a source-rock deposited in a lacustrine environment. • ESI FT-ICR MS is a trustworthy way to achieve a geochemical assessment. Abstract Three crude oils recovered from three different wells of the Mero Field in the pre-salt of the Santos Basin were selected for detailed geochemical analysis. The samples were analyzed using a 7.2 T LTQ FT-ICR MS instrument by negative electrospray ionization (–ESI), focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing compounds (NSO). Additionally, a combination of traditional geochemical methods including GC-FID, GC-MS, and carbon isotopic composition (whole oil and n -alkanes) were used to assess the samples. Through this work, it was demonstrated that –ESI FT-ICR MS is a reliable method for assessing crude oil composition and providing information about the origin and thermal maturity of the samples. Results showed that the dominant heteroatom classes are N 1 , O 2 , N 1 O 1 , and O 1. Due to the similarity of double bound equivalent (DBE), which means number of unsaturation present in an organic molecule, and carbon number distributions for the N 1 class species it is possible to suggest that Mero's filling history had an oil charge representing the peak of the oil window (0.7–0.9 %Ro) and that the oils were generated by a source rock deposited in a lacustrine environment. [ABSTRACT FROM AUTHOR]

Highlights • Petroleomic was applied to 69 off-shore Brazilian crude oils samples. • Kerogen type plays an important control on NSO compounds. • Clear separation based on polar species found in marine and lacustrine oils. • Negative ESI FTICR-MS can be used to perform geochemical assessment in crude oils. Abstract Lacustrine and marine crude oils from different off-shore Brazilian basins were analyzed using a 7.2 Tesla LTQ FTICR-MS instrument. The samples were analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. We also employed a combination of other geochemical methods, such as GC-FID and GC-MS analyses, to characterize and assess the depositional environments of the different oil families. The results indicate that lacustrine oils tend to be enriched in Nx compounds, while marine oils show preference for Ox compounds. The dominant heteroatomic classes in crude oils are N1, followed by O1, O2, and N1O1 with remarkable differences in their distributions between marine and lacustrine, strongly suggesting the control by the kerogen type of the heteroatomic compounds found in these crude oils. Considerable differences in the DBE distribution of the main classes analyzed between the crude oils allowed an efficient geochemical characterization regarding their origin. The use of negative ESI FTICR-MS as a geochemistry tool can provide additional information beyond that obtained with currently employed geochemical methods, resulting in the full comprehension of crude oil composition. [ABSTRACT FROM AUTHOR]

Thermal maturity of late Pliensbachian-early Toarcian organic-rich sediments in the Grands Causses (Suèges section), Quercy (Caylus section) and Pyrenean (Pont de Suert section) basins was determined through multiple parameters, including Spore Coloration Index (SCI), hydroid random reflectance (HR r ) and spectral fluorescence of Tasmanites algae ( λ max ). The main objective of this study is to test the effectiveness and make comparisons of organic matter thermal maturity in these three sections by different techniques and particularly hydroid reflectance. For the Suèges section SCI presented a value of 3.5–4.0. HR r ranges between 0.36% and 0.47%, which corresponds to 0.45%–0.52% VR eq , and shows a good correlation with SCI values. Spectral fluorescence analysis presents a λ max of 560 nm for most samples. The fluorescence spectral maximum seems to be redshifted in comparison to other thermal maturity parameters. The Caylus section exhibited SCI of 3.5–4.0. HR r ranges between 0.32% and 0.50% corresponding to 0.42%–0.54% VR eq . Spectral fluorescence analysis points out a λ max of 560 nm, displaying a good correlation with SCI. When R eq values determined through SCI are compared with equivalent vitrinite reflectance values determined through λ max , a redshift of the fluorescence spectrum maximum is detected. For the Pont de Suert section SCI ranges between 8.0-8.5 and 8.5–9.0. HR r varies between 0.85% and 1.18% which corresponds to 0.76%–0.98% VR eq . Even though there are lower values than those obtained by SCI, VR eq is reliable and acceptable to determine the thermal evolution stage. Furthermore, HR r values also present a good correlation with SCI. These data indicate that the majority of the samples from the Suèges and Caylus sections are in the immature to early mature evolution stages and Pont de Suert section samples are in late mature to early overmature evolution stages for liquid hydrocarbons generation, supporting a very similar thermal evolution for the Grands Causses and Quercy basins and an entirely different thermal history for the Pyrenean Basin. This is in accordance with the similar tectonic and sedimentary context of the Quercy and Grands Causses basins. The Pont de Suert section, located near the collision front of the Pyrenees mountains, records a more complex sedimentary and tectonic history. In addition, this study presents the first reflectance data for Jurassic hydroids, which show a good correlation with other rank parameters. [ABSTRACT FROM AUTHOR]

The thermal maturity level impact on polar compounds was analyzed for a suite of hydrous pyrolysis (HP) products using a 7.2 Tesla LTQ FTICR-MS instrument. The sample suite was analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. The HP experiments were performed under isothermal conditions for 2 h at eleven different temperatures (300, 310, 320, 325, 330, 340, 345, 350, 355, 360 and 365 °C) to simulate the full range of thermal levels starting at early bitumen generation to maximum oil generation. The maturity suite samples consist of one immature bitumen (original sample), eleven expelled oil samples and eight residual bitumen samples. In general, O x compounds are destroyed by decarboxylation and dehydration with increasing maturity; sulfur compounds decrease; the aromaticity and degree of condensation increase; and steranoic and hopanoic acids decrease. Additionally, we investigated fluid retention properties comparing the carbon number distribution between the expelled oil and residual bitumen samples from each experiment. The maturity related changes of the acidic O 2 compounds in the expelled oil samples led us to create several regressions that we propose as new maturity parameters covering the full range of oil generation. [ABSTRACT FROM AUTHOR]

The Pliensbachian–Toarcian (Lower Jurassic) in the Lusitanian Basin (Portugal) is particularly well exposed through marl-limestone alternations very rich in nektonic and benthonic macrofauna. In the general context of Toarcian Oceanic Anoxic Event (T-OAE), the Lower Toarcian (Polymorphum and Levisoni ammonite zones) marks important sedimentological changes in the marine paleoenvironment. To better understand the paleoenvironmental changes that occurred during the latest Pliensbachian–early Toarcian, a high-resolution study of organic matter was undertaken in the Alcabideque section, in the northern sector of the basin. Based on the analysis of 14 samples from a section 20 m thick, this study involved organic geochemistry [total organic carbon (TOC), sulfur and biomarkers] and palynofacies. The results confirm that sediments are particularly poor in organic matter, with the highest TOC values reaching 0.41 wt.% around the top of Polymorphum Zone. The palynofacies analysis provides evidence that the organic matter largely consists of particles belonging to phytoclasts and palynomorphs groups. The phytoclasts present were generally degraded and oxidized, with significant representation in the Emaciatum and Polymorphum zones. The palynomorphs were mainly composed by sporomorphs, with a sporadic increase in marine palynomorphs (mainly dinocysts) at the top of the Emaciatum and Polymorphum zones. Continental organic matter was predominant at the base of Levisoni Zone (T-OAE), through the deposition of brownish marls (Chocolate Marls), which was confirmed by the occurrence of tetrads and polyads (pollen grain agglomerates), and by biomarkers, with the major presence of long-chain n -alkanes, n- alkane C17, C20 tricyclic terpane, C24 tetracyclic terpane and C29 regular sterane. The gammacerane index shows a peak at the top of Polymorphum Zone, clearly associated with the increase of marine palynomorphs and the maximum marine influence in the series. [ABSTRACT FROM AUTHOR]

The artificial maturation changes of the humic coal organic matter (OM) from late diagenesis to the semianthracite stage of coalification were investigated using the closed-system pyrolysis. Two extracted coal samples, a subbituminous coal 26C (with a random vitrinite reflectance Rr = 0.42%) and a high volatile bituminous coal 30C (Rr = 0.56%), were pyrolysed during 4 h at two different temperatures, 250 °C and 400 °C. The applied petrographic and organic geochemical analyses showed that the humic coal OM is sensitive to the artificial thermal stress. A good correlation between the changes in petrographic characteristics and the derived liquid products was observed. The contents of all vitrinite macerals, as well as total vitrinite, increased during the thermal maturation. The abundance of liptinite macerals decreased during the maturation and they practically disappeared after 4 h of the pyrolysis at 400 °C. The total inertinite contents increased after the pyrolysis at 250 °C, yet to be decreased after the pyrolysis at 400 °C. The content of organic carbon increased from coals to the solid residues at 400 °C, whereas the contents of total hydrogen and sulphur decreased. The yields of gases, liquid products and solid residues at respective temperatures were very similar for both coals, regardless of the rank. As expected, the pyrolysis at 400 °C gave higher gas and liquid yields than at 250 °C. Regarding the liquid pyrolysates, more pronounced changes were observed in the distribution of aromatic compounds than in saturated biomarkers. The distributions of the aromatics indicate that apart from cracking and isomerisation (the formation of thermodynamically more stable isomers), the reactions of dehydrocyclization, condensation (the formation of more stable conjugated systems) and aromatization, as well as reactions involving H 2 S, elemental sulphur and reactive phenyl radicals released during the pyrolysis, also play an important role. It was shown that bentonitic clay plays a more important role in the subsequent aromatization of the OM than the initial maturity of the coal OM. n -Alkane parameters were useful at lower maturities (up to ~ 0.75% Rr), whereas sterane, naphthalene and phenanthrene maturity ratios are applicable at higher maturities (> 0.75% Rr). Hopane parameters showed variable sensitivities over the investigated maturity range (0.5–1.8% Rr). The most sensitive maturity parameters in the wide range of the humic OM maturity (0.5–1.8% Rr) are vitrinite reflectance, phenylnaphthalene ratio, methylchrysene index 2 and a parameter proposed in this study, based on the distribution of methylfluorenes (MF): (2- + 3-MF) / (1- + 4-MF). Generally, maturity parameters based solely on the isomerisation reactions of alkylaromatics, which do not include alkylation/dealkylation processes, are more appropriate for the humic OM, particularly at higher maturities. [ABSTRACT FROM AUTHOR]

The unusual occurrence of calcretes and prominent organic matter in the Middle Jurassic (Lower Bathonian, Serra de Aire Formation) of the Lusitanian Basin of western Portugal (Western Iberian Margin) revealed a complex palimpsest exposure record, here interpreted as reflecting hydrological changes caused by phases of emergence and immersion. It serves as a potential model for understanding stratigraphic development at lowstand surfaces in carbonate successions. The exposure-dominated facies association grades upwards into peritidal and lagoonal limestones, and the interval is assigned to the regressive peak of a Transgressive-Regressive Facies Cycle (2nd order) of the thick Middle Jurassic carbonate ramp succession. The Galinha Quarry, Fátima region, NE of Lisbon, a type section for this lowstand assemblage, exhibits varied calcretes, with black-clasts, interbedded with, and grading into: organic-rich marly/clayey seams and lenses, locally with carbonate nodules; carbonates with evaporite traces; microbial laminites; black-clast and fenestral limestones; some lithofacies are dolomitized. The palynofacies contains phytoclasts associated with less refractory, more prone to degradation components, which suggests natural combustion/pyrolysis (wild fires). The lowstand surface represents a low relief landscape with small depressions/ponds bordering a more distal marginal-littoral setting; the partly subaerial and partly subaqueous settings were subjected to lengthy exposure and to fluctuating, very shallow water bodies and water table. Coeval climatic regime was a seasonally dry/wet one, with dry/semi-arid phases dominating over the sub-humid, as shown by the combined record of intense calcrete development, rhizogenic structures, microbial mats, brecciation, desiccation, evaporites and wild fire evidence. However, sea level rise caused changes to shallow, sea-water influenced restricted lagoonal-peritidal settings. Comparisons and differences with modern and ancient coast marginal carbonates are made to provide a guide to the variability in such lowstand deposystems in the stratigraphic record. [ABSTRACT FROM AUTHOR]

The study of the organic matter present in sedimentary rocks is fundamental for the characterization of the potential source rocks as well as to define the depositional paleoenvironments. Parameters of organic petrology and organic geochemistry, and their variations along sedimentary successions are essential tools to achieve these goals. Two borehole successions (Freixial-1 and Benfeito-1) from Arruda sub-basin (Lusitanian Basin), that comprise siliciclastic–carbonate deposits of Jurassic age, have been studied in order to characterize the organic matter and its vertical variability as well as its hydrocarbon potential. Palynofacies and geochemical data indicate both, marine (including zooclasts) and terrestrial organic matter where the phytoclasts predominated despite an important contribution of the amorphous organic matter (AOM). Different types of solid bitumen were observed. Most of the analyzed samples have total organic carbon content (TOC) lower than 1 wt.% and Hydrogen Index (HI) values lower than 100 mgHC/g TOC, revealing types III and IV kerogen. However, one set of samples exhibit TOC values higher than 1 wt.% and higher HI values depicting a type II kerogen. The biomarker data showed a dominance of n -alkanes with 15–30 carbon atoms having a unimodal distribution. Pristane/Phytane ratio varies between 0.04 and 1.84 indicating an alternation of oxic–anoxic conditions along the sequences. Typical terpane distributions are characterized by the presence of tricyclic and tetracyclic terpanes as well as pentacyclic terpanes (rare in carbonated samples from Freixial-1 borehole). The amount of 17α (H),22,29,30-trisnorhopane (Tm) usually exceeds the amount of 18α (H),22,29,30-trinorneohopane (Ts). The values of the ratio 22S/(22S + 22R) epimers of C32 homohopanes revealed that most samples reached equilibrium values. The 20S/(20S + 20R) and ββ/(αα + ββ) isomerization ratios in C29 sterane, calculated for the studied samples, range between 0.19–0.61 and 0.20–0.70, respectively, with several samples reaching the equilibrium values. The vitrinite reflectance values are higher than 0.5% indicating that the organic matter reached the oil generation window. According to the data obtained in this study, the Abadia, Montejunto, Cabaços and Brenha Formations can be considered potential source rocks of hydrocarbons (gas and/or oil) in this section of the Lusitanian Basin. [ABSTRACT FROM AUTHOR]

The main goal of this study was to quantitatively and qualitatively characterize the sedimentary organic matter (OM) and demonstrate the usefulness of geochemistry and palynofacies analysis for obtaining paleoenvironmental data for the Holocene in southernmost Brazil. The results indicate that during the time interval from 10,586 cal yr BP to the present, the study area housed a wetland characterized by different hydrologic regimes. The basal peaty deposits correspond to a phase influenced mainly by the groundwater table, whereas the upper deposits composed of silty organic mud indicate fluvial influence related to river overflow events. In a similar manner, the TOC (total organic carbon) and TS (total sulfur) contents are higher in the basal portion of the profile, decreasing toward the top. These findings could be related to granulometry alterations that are linked to hydrologic regimes or anthropogenic interference in the landscape dynamics. Anomalous TS content observed in one of the samples might be due to an external source and perhaps related to the presence of thermal springs in the region. These types of areas have potential as a modern reference that can be applied in the reconstruction of past analogous environments such as coal deposits associated with fluvial paleoenvironments. [ABSTRACT FROM AUTHOR]

Sepetiba Bay (SB) is one of the Brazilian coastal regions most impacted by anthropogenic activities due to increased population density, the installation of tourist and industrial mega-developments, and essential port, agricultural and fishing activities. Given the great concern about its environmental quality, several studies have focused on it, especially since the 1980s. This study aims to analyze the current ecological risk by potentially toxic elements (PTEs) in the bottom sediments of Sepetiba Bay (SB). The work integrates numerous variables (physicochemical, textural, and geochemical) analyzed at 73 stations in SB and the transition area to Ilha Grande Bay. The results show that the sediments in the eastern-inner region of Sepetiba Bay, along the Itacuruçá coast, and in some areas near the Marambaia Barrier Island (MBI) are severely polluted by Cd (4.47 mg kg−1) > Sn (7.31 mg kg−1) > Zn (824 mg kg−1) > Co (12.50 mg kg−1) > Pb (36.6 mg kg−1) > Cr (65.0 mg kg−1) > Fe (4.98 %) > Ni (21.4 mg kg−1) > V (66.0 mg kg−1), (maximum values), and highly polluted by U (2.8 mg kg−1) > Mn (857 mg kg−1) > Sb (0.32 mg kg−1) > Tl (0.63 ppm) > Hg (170 μg kg−1) > As (11.2 mg kg−1), maximum values. The pollution load index (PLI) and contamination degree (Cdeg) indexes also indicate considerable to very high contamination, indicating severe pollution in that zone. The Potential Ecological Risk Index (PERI) suggests high (160≤RI < 320) and very high (RI ≥ 320) ecological risk in the inner and middle areas of Sepetiba Bay by Cd > Hg > Cu > Co > Pb > Sn > Tl > Ni. Relatively low pH and Eh values were identified in the inner region of Sepetiba Bay, indicating eutrophication processes. A comparison of the concentration factors in the surface sediments of SB in 2009–2011 and 2022 suggests that there has been a general increase in contamination by metals, namely Fe, Mn, Pb, Co, Cr, Ni, U, V, and Hg. Although metals accumulate more pronounced in the inner and the most impacted marginal areas of Sepetiba Bay, their enrichment factors (EF) indicate an increase in contamination in the outer sector. Metals are being imported from the nearby oceanic region, where there is a dredging site, to the outer sector of Sepetiba Bay. Thus, the choice of dredged spoil disposal sites and how contaminated dredged material is deposited needs to be better addressed and is still a challenging task. This aspect often results in problems being transferred from one region to another. The results suggest that mitigation measures must be adopted to prevent the situation from worsening. • Worsening of metal pollution in 2022 compared to 2009–2011 in Sepetiba Bay. • There are two main axes of pollution in Sepetiba Bay: in the inner and outer areas. • 45% of the analyzed sites located in the inner area have high/very high potential ecological risk. • Transferring pollutants from the inner to the outer zone by dredging activities. [ABSTRACT FROM AUTHOR]

Gaiteiros-1 borehole, located in the central Lusitanian Basin (Portugal), drilled a continuous Jurassic (Hettangian to Kimmeridgian) sedimentary sequence. Forty-one samples were selected for this study to characterize the dispersed organic matter and its vertical variation along Gaiteiros-1 borehole and to evaluate the environmental changes based on palynofacies and bulk geochemistry analyses. Gaiteiros-1 borehole lithological sequence is characterized by a low organic carbon content, which varies between 0.10 wt% and 0.83 wt%, in Candeeiros carbonates and Lower Jurassic Coimbra Formation, respectively. The insoluble residue content indicate a carbonated character in almost the entire sequence, except for Kimmeridgian samples. The palynofacies analysis evidences the presence of the main groups of kerogen (Phytoclats, Amorphous and Palynomorphs) with a dominance of the amorphous group in the carbonated samples and phytoclasts in Kimmeridgian detritic samples. Different types of amorphous particles were identified, suggesting periods of reworking by bacterial activity and primary bioproductivity in depleted oxygen environments. Despite the dominance of amorphous particles, the kerogen groups vertical variation provides information that reveals changes in the depositional environment. The kerogen assemblage of the Candeeiros facies suggests a stratified water column, with well-oxygenated layers, responsible for high primary productivity periods, which allowed for the development of zooplankton, preserved in the form of zooclasts fragments and foraminiferal test-linings. The contribution of the Palynomorph group is scarce during the Lower-Middle Jurassic but increases in the Upper Jurassic. This modification in the kerogen assemblage reflects changes in the sea level, oxygenation conditions, climate and proximity to the terrestrial source area. The presence of Coleochaete -like freshwater algae was detected for the first time in the Lusitanian Basin, suggesting more restrictive conditions during the Late Oxfordian. During the Kimmeridgian, the amorphous material disappears and phytoclasts, mainly opaque phytoclasts, come to dominate the kerogen assemblage, as a result of terrigenous sediments input, due to the great proximity to the terrestrial source area. • Palynofacies are reported for Gaiteiros-1 sedimentary sequence (Lusitanian Basin). • Monotonous carbonated record dominated by amorphous organic matter. • Non-carbonate sedimentation characterized by terrestrial organic matter. • Different depositional environments, from carbonate platform to fluvio-deltaic. • Coleochaete algae: first occurrence in the Jurassic fossil record. [ABSTRACT FROM AUTHOR]

The Toarcian Oceanic Anoxic Event (TOAE) is characterised by a perturbation of the global carbon cycle and the widespread deposition of organic matter (OM)-rich strata/sediments in the northern areas of the West Tethys Shelf, in several northern European epicontinental basins. Contrariwise, in the southern areas of the West Tethys Shelf such as western and southern Iberian, and northern Gondwana margins, OM-rich strata/sediments are spatially and temporally restricted. To better understand the relationship between OM production, depositional conditions, and palaeoceanographic controls on the occurrence of OM-rich facies in the northern Iberian margin, we collected and analysed 18 samples from the Rodiles section (Asturian Basin) for geochemical (total organic carbon-TOC, total sulfur-TS, δ13C Kerogen , and δ13C Wood) and palynofacies analysis. The studied upper Pliensbachian–lower Toarcian succession has TOC values reaching up to 2.9 wt%. The relative dominance of non-opaque phytoclasts and the δ13C Kerogen values (average of ~ −24‰) in the lowermost Toarcian (Tenuicostatum Zone) agrees with previous interpretations indicating that this area was located in a dominantly winter-wet climate zone. A change in the kerogen assemblages is observed at the Tenuicostatum/Serpentinum zones boundary (onset of TOAE), related to an increase in amorphous OM (AOM). A slight increase in non-opaque phytoclasts and terrestrial palynomorphs, and a negative δ13C Kerogen excursion (reaching −31.5‰) is recorded in the same interval. These observations suggest a increase in continental weathering and fluvial runoff associated with more humid conditions, likely resulting in increased superficial productivity and deposition and preservation of OM under, at least, suboxic conditions. Above the TOAE interval, the δ13C Kerogen record (values around −24‰) and the drastic drop in TOC and AOM content indicate that bottom water oxygenation improved after the TOAE. Our results demonstrate a link between early Toarcian climate dynamics and the deposition of OM-rich strata/sediments. • Organic matter-rich sediments occur in the Asturian Basin. • The studied kerogen assemblages are mostly of terrestrial affinity. • Increase in abundances of TOC, amorphous and terrestrial organic matter during TOAE. • Improved bottom water oxygenation caused decline in TOC and amorphous organic matter after TOAE. • A link between kerogen assemblages, δ13C Kerogen and winter-wet climate is demonstrated. [ABSTRACT FROM AUTHOR]

A Wenlock (Silurian) sedimentary continuous sequence was sampled in the Dornes region (Central Iberian Zone, Portugal) to characterize the organic matter type using different microscopic analyses (organic petrology and palynofacies). Total organic carbon (TOC) was also determined. Samples are part of Foz da Sertã Formation and correspond to mudstone, punctually with sandstone, rich in organic matter (mean TOC value of 5.1%). Whole rock samples showed a dominance of non-granular graptolites (lath- and blocky-shape) and solid bitumen. Lath-shape graptolites display the characteristic segmented structure. In the blocky-shape graptolites, the fusellar layers of the graptolite wall are well marked and are an important distinctive feature. Foz da Sertã graptolites are optically anisotropic as well as the solid bitumen. Non-granular graptolite's maximum reflectance varies from 1.43 to 3.94% and solid bitumen maximum reflectance oscillates between 1.09 and 2.22%. Vitrinite reflectance equivalent was calculated using Bertrand and Malo's equation (values between 1.97 and 3.72%) denoting a post-mature stage for the organic matter. No relation was established with confidence between graptolite maximum reflectance and solid bitumen maximum reflectance. The palynofacies study confirmed not only the presence of graptolite and solid bitumen but also amorphous material derived from graptolite. Under transmitted white light, graptolite features were not noticed. To improve the palynofacies characterization, reflected white light was used on slides, thus exposing distinctive graptolite features. The different lights and preparation types used allowed a better characterization of the organic matter present in Foz da Sertã Formation samples, mainly the graptolites. The use of reflected white light, in the palynofacies study, proved to be extremely important in the description of the graptolite features. • Silurian organic matter from Dornes region were studied. • Graptolites, amorphous particles and solid bitumen dominate the kerogen assemblage. • Organic matter are in a post-mature stage. • Reflected white light observation was essential to distinguishing graptolite features. [ABSTRACT FROM AUTHOR]

Lakes can be classified as open, semi-closed, and closed based on the balance between accommodation space and sediment–water fill. Different lake types can coexist in adjacent basins and rapidly change throughout time from one type to another. Understanding the processes that result from shifts in a lake's hydrological properties can be challenging, as well as characterizing its sedimentary products. The Aptian Codó Formation, in the Parnaíba Basin, north–northeast Brazil, contains in its record a complex facies succession deposited in a continental lacustrine system. In order to better understand the depositional aspects of different lake types, we characterized the lower portion of the Codó Formation using a multi-proxy approach. We combined litho- and microfacies analysis, ichnology, bulk chemical data, mineralogy, isotopic geochemistry, and organic matter analysis in the recently drilled, fully recovered borehole, 2-CO-1-MA. We defined eight lithofacies: bioturbated siltstones, dark gray mudstones, laminites, stratiform and domal stromatolites, heterolites rich in ostracods and organic muddy, and anhydrite and gypsum rocks. The isotopic data and the palynofacies analysis pointed out the existence of restricted conditions (TOC up to 19.6 wt%) with intermittent connections with seawater. Integrating all techniques, we interpreted five depositional stages: expanded lake, brackish ephemeral lake, perennial shallow lake, evaporitic sabkha, and stratified lake. These stages were influenced by the relation between inflow and evaporation rate, which were the main controls on sedimentation in the lacustrine-sabkha system studied. Our findings provide a detailed description and interpretation of the paleoenvironmental conditions related to the alternation from open to closed lakes, combining sedimentological, geochemical, and palynological characteristics of an inland lake system. [ABSTRACT FROM AUTHOR]

Lower Jurassic sedimentary successions in many central and northern Atlantic basins include relatively thick organic-rich intervals. Despite intense research, it is still unclear which mechanisms led to the deposition of these sediments during the Early Jurassic. In this talk, we will (1) present a detailed temporal and geographical framework of Sinemurian and Toarcian organic matter preservation intervals (OMPIs; subdivided into local, regional, and superregional) and (2) broadly constrain the relationship of OMPIs with the Early Jurassic δ13C record. For this, we combine an in-depth analysis of the distribution of organic-rich facies in the Sinemurian and Toarcian with new geochemical data [total organic carbon (TOC) and organic matter pyrolysis] from Portugal, Spain, and Morocco. The developed OMPI framework suggests a strong local control on organic matter preservation during most of the Sinemurian. Regionally widespread organic-rich facies are associated with the most negative δ13C values of the broad Sinemurian-Pliensbachian negative carbon isotopic trend (including the Sinemurian-Pliensbachian Boundary Event). Pliensbachian OMPIs are expressive in the areas bordering the proto-Atlantic Ocean and are often linked with positive δ13C excursions and short-lived warm intervals, but OMPIs are also observed for the Late Pliensbachian cool interval. Toarcian maximum TOC content occurs with the positive 513C (recovery) trend following the 513C negative shift typically linked to the Early Toarcian Oceanic Anoxic Event (T-OAE). However, superregional OMPIs predate and postdate the T-OAE, indicating that conditions favouring the preservation of organic matter (increased productivity and/or enhanced preservation) were not restricted to the T-OAE interval. We will also briefly discuss how future research should aim to disentangle (1) the complexities in estimating original TOC and organic carbon accumulation rates, (2) temporal and spatial variability in environmental or Earth system feedback mechanisms driving sedimentary carbon sequestration, and (3) their combined impact on the global carbon cycle. [ABSTRACT FROM AUTHOR]

Scarce knowledge is available concerning the diatom ecology of hypersaline environments and their potential to use as bioindicators. The aim of this study was to characterize and quantify diatom assemblages from Vermelha Lagoon associated with environmental parameters in order to establish environmental quality bioindicators for hypersaline environments. Species distribution displayed a weak relationship with environmental parameters analyzed in DCA analyses. The cluster analyses evidenced the presence of four diatom groups in the lagoon: Group I - located on the south margin of the lagoon, represented by N. arenaria; Group II - located in the north, the central sector and near the communication channel with Araruama Lagoon, dominated by F. interposita. The Group III - distributed in the shallowest regions, where primary productivity is high. Species H. acutiuscula and C. placentula in this group reached high relative abundance values. Group IV is characterized by increased salinity and lipids values, characterizing hypertrophic sediment conditions. These stations were located in the Saltpan water catchment and were characterized by a decreased number of species and the dominance of A. robusta. • This study investigated the sediment quality of the Vermelha Lagoon (Rio de Janeiro, Brazil) through an integrated approach. • It was analyzed the physicochemical, sedimentologial and geochemistry parameters on the diatom species distribution. • It is the first record of diatoms from hyipersaline environments of Brazil. • These results provide a baseline for paleoenvironmental and environmental studies in carbonate systems. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to document the changes observed in the Quaternary dinoflagellate assemblages from 80 core samples from the Campos Basin. The Interglacial (Subzone X1), Glacial (Subzones Y5 to Y2), Last Glacial Maximum (Subzone Y1) and Post-Glacial (Zone Z) intervals were identified. High abundance of Operculodinium centrocarpum suggests the warm, high salinity and nutrient-poor water conditions dominated the upper water column of the Campos Basin. The climate and oceanic current dynamic of the continental slope of the Campos Basin appears to has been a significant controlling factor in the distribution of dinocysts, particularly of O. centrocarpum , during the Pleistocene/Holocene transition. [ABSTRACT FROM AUTHOR]

Vermelha Lagoon is a hypersaline shallow transitional ecosystem in the state of Rio de Janeiro (Brazil). This lagoon is located in the protected area of Massambaba, between the cities of Araruama and Saquarema (Brazil), and displays two quite uncommon particularities: it exhibits carbonate sedimentation and displays the development of Holocene stromatolites. Due to both particularities, the salt industry and property speculation have been, increasingly, generating anthropic pressures on this ecosystem. This study aims to apply a multiproxy approach to evaluate the trophic state of Vermelha Lagoon based on physicochemical parameters and geochemical data for the quantification and qualification of organic matter (OM), namely total organic carbon (TOC), total sulfur (TS), total phosphorus (TP) and biopolymeric carbon (BPC), including carbohydrates (CHO), lipids (LIP) and proteins (PTN). The CHO/TOC ratio values suggest that OM supplied to the sediment is of autochthonous origin and results, essentially, from microbial activity. The cluster analyses allowed the identification of four regions in Vermelha Lagoon. The Region I included stations located in shallow areas of the eastern sector of Vermelha lagoon affected by the impact of the artificial channel of connection with Araruama Lagoon. The Region II, under the influence of salt pans, is characterized by the highest values of BPC, namely CHO promoted by microbiological activity. The Region III include stations spread through the lagoon with high values of dissolved oxygen and lower values of TP. Stromatolites and microbial mattes growth was observed in some stations of this sector. Region IV, where the highest values of TOC and TS were found, represents depocenters of organic matter, located in general in depressed areas. Results of this work evidences that the Vermelha Lagoon is an eutrophic but alkaline and well oxygenated environment (at both water column and surface sediment) where the autotrophic activity is greater than heterotrophic one. These particular conditions make this a special and rare ecosystem. [ABSTRACT FROM AUTHOR]

A gelified wood from the late Aptian Maceió Formation (Sergipe–Alagoas Basin, northeastern Brazil) was studied under scanning electron microscopy and organic petrography allowing for the record of the fossil-species Brachyoxylon patagonicum , likely belonging to the Cheirolepidiaceae family. The anatomical structure of the secondary xylem is characterized by mixed type of radial tracheary pitting, composed exclusively by uniseriate bordered pits, in separated, contiguous and compressed arrangements. Cross-field pits are of the araucarioid type, xylem rays are uniseriate or rarely partially biseriate, and probable sporadic traumatic resin canals are present. The present record expands the paleobiogeographic distribution of the fossil-genus in South America and amplifies its climatic tolerance, since the parent plants lived in the Aptian Tropical Equatorial Hot arid belt. The presence of fungal remains within the wood tissue, and the absence of signs of plant defense against fungal decay suggest saprophytic fungus–wood interactions that likely occurred during a stage of aerobic exposure before burial. • A record of cheirolepidiacean wood for the Brazilian Aptian. • Wood preservation by gelification was determined by organic petrography. • Periquatorial occurrence of Brachyoxylon amplified its climatic tolerance. [ABSTRACT FROM AUTHOR]

The analyses of radiolarian assemblages were carried out from low-latitude DSDP Site 355 (Leg 39), drilled in the Brazil Basin, South Atlantic Ocean. A total of 98 early to middle Eocene radiolarian events were identified in this site. The standard low-latitude radiolarian zonation was adopted for the Site 355 cores, and it allowed the identification of seven radiolarian zones: Podocyrtis mitra (RP14), Podocyrtis ampla (RP13), Thyrsocyrtis triacantha (RP12), Dictyoprora mongolfieri (RP11), Theocotyle cryptocephala (RP10), Phormocyrtis striata striata (RP9), and Buryella clinata (RP8). The radiolarian events at Site 355 were compared with previous studies from low and mid-latitudes, showing a good correlation with the low-latitude regions. On the other hand, 11 radiolarian events were clearly diachronous between low and mid-latitudes. • Record of radiolarian events from the early to middle Eocene South Atlantic. • Radiolarian biostratigraphy of the early to middle Eocene interval at DSDP Site 355. • Biostratigraphic correlations with previously studied throughout the Atlantic and Pacific oceans. • An analysis of the diachroneity between low and mid-latitudes Eocene radiolarian events is presented. [ABSTRACT FROM AUTHOR]

Evidences of paleowildfires from the upper coal seam S from the Faxinal Coalfield have been analyzed through petrographic, fluorescence, and scanning electron microscopy (SEM) specifically at the base (1) and top (2) boundaries of an interlayered tonstein bed and revealed recurrent charcoal deposition in the peat-forming environment. An unusual accumulation of adjacent, large-sized (21.8 × 13.4 cm and larger) charred logs occurs throughout the coal seam area (1.6 km 2 ) beneath the tonstein bed (boundary 1) reflecting an extensive wildfire event in hypautochthonous/autochthonous conditions. The logs display a semifusinite–vitrinite–semifusinite sandwich-like structure ( sensu Jones et al., 1993) indicating burning in growth position, and reflectance measurements below 1%Ro suggest that this was a low-temperature fire. Dryness in the peatland during the fire event was clearly detected by altered fluorescence of spores and algae. Corroborating previous studies, the paleoecological setting can be characterized as a swamp forest based on the presence of pollen clusters and organs observed under fluorescent light and on the identification under SEM of the morphogenus Agathoxylon Hartig as a single wood type, reflecting the dominance of arborescent gymnosperms (glossopterids) in the peatland. Homogenized cell walls observed under SEM ratified the recognition of the material as charcoal. The reestablishment of regular conditions of peat deposition following the major fire episode is represented by alternate bands of vitrinite and semifusinite in both boundaries 1 and 2, suggesting an oscillation from dry to wet conditions in the climate pattern and the occurrence of wildfires as common and systemic events. Fire ignition, activity, and spread in the peat-forming environment resulted from a combination of lightning strikes, dryness, fuel abundance, and high atmospheric oxygen levels. [ABSTRACT FROM AUTHOR]

Hydrous pyrolysis (HP) experiments were used to investigate the petroleum composition and quality of petroleum generated from a Brazilian lacustrine source rock containing Type I kerogen with increasing thermal maturity. The tested sample was of Aptian age from the Araripe Basin (NE-Brazil). The temperatures (280–360 °C) and times (12–132 h) employed in the experiments simulated petroleum generation and expulsion (i.e., oil window) prior to secondary gas generation from the cracking of oil. Results show that similar to other oil prone source rocks, kerogen initially decomposes in part to a polar rich bitumen, which decomposes in part to hydrocarbon rich oil. These two overall reactions overlap with one another and have been recognized in oil shale retorting and natural petroleum generation. During bitumen decomposition to oil, some of the bitumen is converted to pyrobitumen, which results in an increase in the apparent kerogen (i.e., insoluble carbon) content with increasing maturation. The petroleum composition and its quality (i.e., API gravity, gas/oil ratio, C 15+ fractions, alkane distribution, and sulfur content) are affected by thermal maturation within the oil window. API gravity, C 15+ fractions and gas/oil ratios generated by HP are similar to those of natural petroleum considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous age. API gravity of the HP expelled oils shows a complex relationship with increasing thermal maturation that is most influenced by the expulsion of asphaltenes. C 15+ fractions (i.e., saturates, aromatics, resins and asphaltenes) show that expelled oils and bitumen are compositionally separate organic phases with no overlap in composition. Gas/oil ratios (GOR) initially decrease from 508–131 m 3 /m 3 during bitumen generation and remain essentially constant (81–84 m 3 /m 3 ) to the end of oil generation. This constancy in GOR is different from the continuous increase through the oil window observed in anhydrous pyrolysis experiments. Alkane distributions of the HP expelled oils are similar to those of natural crude oils considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous age. Isoprenoid and n -alkane ratios (i.e., pristane/ n -C 17 and phytane/ n -C 18 ) decrease with increasing thermal maturity as observed in natural crude oils. Pristane/phytane ratios remain constant with increasing thermal maturity through the oil window, with ratios being slightly higher in the expelled oils relative to those in the bitumen. Generated hydrocarbon gases are similar to natural gases associated with crude oils considered to be sourced from similar Brazilian lacustrine source rocks with Type I kerogen of Lower Cretaceous, with the exception of elevated ethane contents. The general overall agreement in composition of natural and hydrous pyrolysis petroleum of lacustrine source rocks observed in this study supports the utility of HP to better characterize petroleum systems and the effects of maturation and expulsion on petroleum composition and quality. [ABSTRACT FROM AUTHOR]

Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks . In 2012–2013, an interlaboratory exercise was conducted to establish precision limits for the D7708 measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (0.31–1.53% R o ), from organic-lean to organic-rich (1–22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability limits (maximum difference between valid repetitive results from same operator, same conditions) ranged from 0.03 to 0.11% absolute reflectance, whereas reproducibility limits (maximum difference between valid results obtained on same test material by different operators, different laboratories) ranged from 0.12 to 0.54% absolute reflectance. Repeatability and reproducibility limits degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping the other components. Discussion among participants suggested this problem could not be easily corrected via kerogen concentration or solvent extraction and is related to operator training and background. No statistical difference in mean reflectance was identified between participants reporting bitumen reflectance vs. vitrinite reflectance vs. a mixture of bitumen and vitrinite reflectance values, suggesting empirical conversion schemes should be treated with caution. Analysis of reproducibility limits obtained during this exercise in comparison to reproducibility limits from historical interlaboratory exercises suggests use of a common methodology (D7708) improves interlaboratory precision. Future work will investigate opportunities to improve reproducibility in high maturity, organic-lean shale varieties. [ABSTRACT FROM AUTHOR]

This paper presents results of an interlaboratory exercise on organic matter optical maturity parameters using a natural maturation series comprised by three Devonian shale samples (Huron Member, Ohio Shale) from the Appalachian Basin, USA. This work was conducted by the Thermal Indices Working Group of the International Committee for Coal and Organic Petrology (ICCP) Commission II (Geological Applications of Organic Petrology). This study aimed to compare: 1. maturation predicted by different types of petrographic parameters (vitrinite reflectance and spectral fluorescence of telalginite), 2. reproducibility of the results for these maturation parameters obtained by different laboratories, and 3. improvements in the spectral fluorescence measurement obtained using modern detection systems in comparison with the results from historical round robin exercises. Mean random vitrinite reflectance measurements presented the highest level of reproducibility (group standard deviation 0.05) for low maturity and reproducibility diminished with increasing maturation (group standard deviation 0.12). Corrected fluorescence spectra, provided by 14 participants, showed a fair to good correspondence. Standard deviation of the mean values for spectral parameters was lowest for the low maturity sample but was also fairly low for higher maturity samples. A significant improvement in the reproducibility of corrected spectral fluorescence curves was obtained in the current exercise compared to a previous investigation of Toarcian organic matter spectra in a maturation series from the Paris Basin. This improvement is demonstrated by lower values of standard deviation and is interpreted to reflect better performance of newer photo-optical measuring systems. Fluorescence parameters measured here are in good agreement with vitrinite reflectance values for the least mature shale but indicate higher maturity than shown by vitrinite reflectance for the two more mature shales. This red shift in λmax beyond 0.65% vitrinite reflectance was also observed in studies of Devonian shale in other basins, suggesting that the accepted correlation for these two petrographic thermal maturity parameters needs to be re-evaluated. A good linear correlation between λmax and Tmax for this maturation series was observed and λmax 600nm corresponds to Tmax of 440°C. Nevertheless if a larger set of Devonian samples is included, the correlation is polynomial with a jump in λmax ranging from 540 to 570nm. Up to 440°C of Tmax, the λmax, mostly, reaches up to 500nm; beyond a Tmax of 440°C, λmax is in the range of 580-600nm. This relationship places the "red shift" when the onset of the oil window is reached at Tmax of 440°C. Moreover, the correlation between HI and λmax (r²=0.70) shows a striking inflection and decrease in HI above a λmax of 600nm, coincident with the approximate onset of hydrocarbon generation in these rocks. [ABSTRACT FROM AUTHOR]

By the Early Cretaceous, the Araripe Basin (Northeastern Brazil) is interpreted as having gone through a phase of tectonic quiescence, during which rates of sediment accumulation were mostly modulated by climatic variations. The Crato Member (Santana Formation, upper Aptian of Araripe Basin) consists of gray calciferous mudstone and parallel-stratified micritic limestone deposited in a lacustrine environment. The present study applied the principles of cyclostratigraphic analysis in the uppermost carbonate unit of the Crato Member, which comprises laminated limestone displaying a characteristic cyclic alternation of pale to dark laminae, in order to estimate sediment accumulation rates by relating the depositional record with astronomical cycles of known periodicity. An 8.5 m thick limestone succession was analyzed in order to build a time series by using two distinct data sources, namely spectral gamma ray readings and color variation chart. Additionally, petrographic and organic composition analyses were performed to investigate if environmental changes have affected those parameters. Results indicate that darker laminae reflect periods with concentration of sulfite related to relatively anoxic water conditions. The time series analysis allowed for an identification of two different astronomical cycles: (1) Milankovitch cycles, ranging from 18.6 ky to 39.4 ky, resulting in an estimated depositional rate of 3.25 cm/ky, with a total of 261 ky for the deposition of the whole studied interval; (2) Suess solar cycles, ranging 180–200 years, with an estimated depositional rate of 3.3 cm/ky, and a total of 257 ky for the deposition of the same interval. Therefore, this multidisciplinary approach led to the identification of Milankovitch and Suess high frequency solar cycles, based on which it was possible to determine the rate of deposition as well as the time span involved in it. • The cyclostratigraphic method allowed a higher resolution for sedimentation rates. • The deposition of laminated limestones from the Crato Member was influenced by astronomical cycles. • Lake environments allow the identification of climatic influence on deposition. [ABSTRACT FROM AUTHOR]

The analyses of abundant and well-preserved late middle Eocene to early Oligocene radiolarian assemblages were carried out on ODP Site 1090 (Leg 177) sediments in the Atlantic Sector of the Southern Ocean. A total of 83 radiolarian events are identified and correlated with the geochronologic time scale and paleomagnetic polarity data. The high latitude Eucyrtidium spinosum and Eucyrtidium antiquum Interval Zones are recognized in the studied interval at Hole 1090B, and three new subzones are proposed herein for the Eucyrtidium spinosum Zone: Eucyrtidium nishimurae Interval Subzone (Subchrons C17n.2r to C16r), Dendrospyris stabilis Interval Subzone (Subchrons C16n.2n to C13r), and Dicolocapsa microcephala Interval Subzone (Subchron C13r). The bases of these subzones are defined by the first occurrences of Eucyrtidium spinosum, Dendrospyris stabilis and Dicolocapsa microcephala, respectively. The proposal of these subzones could significantly improve the biostratigraphic resolution of the middle to late Eocene interval from high latitude regions. The FOs of Axoprunum irregularis and Eucyrtidium antiquum are nearly synchronous in the Southern Ocean, and could be used to estimate the Eocene/Oligocene boundary. Other radiolarian events such as the FOs of Dendrospyris stabilis, Dicolocapsa microcephala, and Zygocircus bütschli, and the LO of Eucyrtidium nishimurae are synchronous or approximately synchronous in the Southern Ocean. In contrast, the LOs of Axoprunum pierinae, Periphaena decora, and Siphocampe quadrata , and the FO of Artostrobus annulatus are commonly diachronous among different sites in the Southern Ocean. • Record of radiolarian events from the late middle Eocene to early Oligocene of Southern Ocean. • Radiolarian biostratigraphy of the late middle Eocene to early Oligocene interval at ODP Site 1090. • Biostratigraphic correlations with previously studied ODP holes throughout the Southern Ocean. • An analysis presented about the synchroneity and diachroneity of Eocene-Oligocene radiolarian events is presented. [ABSTRACT FROM AUTHOR]

The presence of the fern Weichselia in a restricted sedimentary interval of a drilling core in the Parnaíba Basin (Brazil) was used as a lead for paleoenvironmental interpretation integrating paleobotanical, palynofacies, palynological, organic petrography and clay mineralogy analyses. The fern paleobiogeography was amplified and its association with terrestrial bryophyte gametophytes (Muscites) indicated depositional conditions corresponding to marginal areas of freshwater bodies subjected to frequent flooding under the general fluvial-deltaic conditions so far accepted for the intermediary portion of the Codó Formation. The high dominance of non-opaque phytoclasts and very scarce autochthonous non-marine palynomorphs pointed to a shallow water body linked to marginal areas of fluvial systems in the river outlets, channel margins in estuarine systems, and/or shallow floodplain lakes connected/open to fluvial canals. The very scarce marine palynomorphs (dinoflagellate cysts) suggest a limited influence from unstable environments on coastal margins or estuarine canals. The terrestrial vegetation surrounding the depositional setting, deciphered by palynological analysis, reflected distinct environmental conditions prevailing simultaneously in 1) humid areas dominated by fern communities, and 2) dry-xerophytic areas dominated mainly by Araucariaceae and Cheirolepidiaceae gymnosperms, both as components of a wider Aptian paleoenvironment within the periequatorial latitudes in South America. The results were supported by clay mineralogy that showed abundance of detrital kaolinite over montmorillonite and suggest the dominance of a climatic humidification process and a less expressive semiarid climate in a regional context. • The paleobiogeography of Weichselia is amplified for the Aptian. • Weichselia and Muscites imply freshwater marginal areas under frequent flooding. • Multi proxies imply fluvial/estuarine systems margins and/or shallow floodplain lakes. • Rare marine plankton imply unstable environments on coastal margins/estuarine canals. • A climatic humidification and less expressive semiarid conditions in regional context. [ABSTRACT FROM AUTHOR]

Abstract: A high-resolution carbon and oxygen isotopic bulk carbonate record from organic-rich hemipelagic series of Early–Late Pliensbachian age (~187Ma) is presented for the Lusitanian Basin (Portugal) and compared to the record of other sedimentary basins. This dataset provides an excellent basis for discussing newly raised questions concerning the hypothesis of major carbon cycle perturbations prior to the Toarcian Oceanic Anoxic Event. In addition to the recognition in the studied series of two positive carbon isotope excursions previously defined elsewhere, corresponding to the Ibex and Margaritatus (uppermost Stokesi–Gibbosus subzones) zones, a third positive excursion is identified here for the first time, at the Davoei Zone. In the Lusitanian Basin these excursions are associated with organic-rich facies intervals. The younger excursion may be related to worldwide enhanced preservation of organic matter in the Margaritatus Zone. We suggest that until these organic-rich facies are well age constrained at a wider scale and high-resolution carbon data are provided from other locations, and that worldwide anoxia is proven, this interval should be referred to as an Organic Matter Preservation Interval (Late Pliensbachian OMPI). This period is probably linked with the complex chain of events that eventually led to the Toarcian Oceanic Anoxic Event. [Copyright &y& Elsevier]

The objective of this study is to investigate the relationship between early Toarcian climatic events and the composition of kerogen assemblages in the Lusitanian Basin (Portugal). In particular, we aim to understand how the Pliensbachian–Toarcian Event (Pl–Toa Event) and Toarcian Oceanic Anoxic Event (TOAE) affected the continental areas of the western Iberian margin and how possible variations in continental sources of organic matter (OM) were expressed in marginal-marine and hemipelagic depositional environments during the early Toarcian. We present here a characterisation [total organic carbon (TOC), total sulphur (TS), δ13C in kerogen concentrate (δ13C Kerogen), and palynofacies] of kerogen assemblages from several uppermost Pliensbachian (emaciatum ammonite Zone)–lower Toarcian sections in the Lusitanian Basin (western Iberian margin), including the Peniche section, which contains the Toarcian GSSP. In all sections, TOC concentration is low (average 0.4 wt.%), with the highest values reaching up to 2.1 wt.% in a discrete level located approximately 10.5 m above the base of the levisoni Zone at Peniche. The TOAE negative carbon isotope excursion is observed in kerogen concentrate at the base of the levisoni Zone throughout the basin. Palynofacies analysis demonstrates that the kerogen assemblages are mostly of terrestrial affinity, with the dominance of the Phytoclast Group and terrestrial palynomorphs, and with punctual increases in amorphous organic matter, freshwater (e.g. Botryococcus sp.) and marine microplankton (dinoflagellate cysts, acritarchs, and prasinophyte algae) in specific stratigraphic intervals. A change in palynofacies assemblages associated with the TOAE is observed around the base of levisoni Zone. Although with slight differences between sections, the TOAE interval records an increase in non-opaque, translucent, phytoclasts (NOP) and cuticle fragments, and is also associated with an increased contribution of terrestrial palynomorphs (increase in sporomorphs and Classopollis in tetrads and agglomerates) and decrease in marine palynomorphs. The increases in NOP and terrestrial palynomorphs support the postulated enhancement of the hydrological cycle and increased export of terrestrial OM into marine environments during the early Toarcian, especially during the TOAE, in the western Iberian margin. Understanding the impact of the early Toarcian climatic events on land-based ecosystems may provide important insights into current climate change. • The Lower Jurassic in the Lusitanian Basin is mainly organic matter lean. • The studied kerogen assemblages are mostly of terrestrial affinity. • A link between kerogen assemblages and climate conditions is demonstrated. • During the TOAE δ13C negative trend an increase in terrestrial particles is observed. • A gradual re-establishment of the depositional conditions after TOAE is observed. [ABSTRACT FROM AUTHOR]

The Lower Jurassic Água de Madeiros (AM Fm) and Vale das Fontes (VF Fm) Formations, and the Upper Jurassic Cabaços Formation (Cab Fm) are considered the most important units with petroleum source-rock potential in the Lusitanian Basin, and the likely sources for its widespread hydrocarbon occurrences. Nonetheless, the bottom-water redox conditions during their deposition remain debatable. To resolve this controversy, we investigated whole-rock inorganic geochemical data of the most significant organic-rich levels of the AM, VF and Cab Fms cropping out at basin scale. Significant variations in TOC, TS and redox-sensitive elements contents and their ratios are evident within and between the organic-rich levels of the studied units. A positive covariation between primary productivity proxies, TOC enrichment and paleo-redox proxies for the Lower Jurassic units clearly suggest an interdependence between enhanced primary productivity, organic matter accumulation and bottom-water redox conditions. For the AM Fm, the paleo-redox proxies indicate that the black shales deposition took place beneath bottom-waters that ranged from suboxic to strongly euxinic conditions, with a clear predominance of the latter. A TOC threshold of ~6–7 wt% clearly separates samples deposited under suboxic to anoxic conditions from those deposited under true euxinic conditions, and is interpreted as the minimum amount of organic matter (OM) accumulation within sediments required to sustain H 2 S production at rates that outpaced its consumption through precipitation of sulphides and/or OM sulphurization, allowing the diffusion of H 2 S to the bottom-waters. For the Vale das Fontes Fm, the paleo-redox proxies suggest a prevalence of suboxic to anoxic bottom-waters, despite all black shales displaying TOC contents greater than the above threshold. The less reducing conditions relative to the AM Fm euxinic black shales are attributed to: i) a larger proportion of continental OM; ii) lower reactivity of the OM reaching the sediment-water interface (decreasing oxygen consumption); and iii) higher availability of reactive iron (increasing the buffer effect to H 2 S produced through OM remineralization by sulphate-reducing bacteria). Both units display Mo-EF vs U-EF covariation patterns that deviate from the field of sediments deposited under unrestricted open-marine conditions, towards higher Mo enrichment relative to that of U, indicating an accelerated transport of aqueous Mo to the sediments, consistent with the operation of a metal-oxyhydroxide particulate shuttle linked to Mn and Fe redox cycling within the water column in a weakly-restricted basin. The Mo-COT regression-line slope indicates a moderate degree of bottom-water mass restriction, with [Mo] aq concentration of ~60–70% of the present-day seawater value and bottom-water renewal times of ~10–20 years, akin to the present-day Cariaco Basin. The redox conditions of the Cab Fm organic-rich levels are dependent on the location of the depositional environment in the basin, with deposition taking place beneath oxygenated bottom-waters at Cabo Mondego, and under suboxic conditions at Vale de Ventos and Pedrógão, the latter denoting a larger degree of oxygen depletion than the former. In this context, the overall potential for OM preservation should increase from Cabo Mondego to Vale de Ventos and Pedrógão. • Redox sensitive elements elucidate the redox conditions of Jurassic organic-rich levels. • Água de Madeiros Fm black shales were deposited predominantly under euxinic conditions. • Vale das Fontes Fm black shales were deposited predominantly under suboxic to anoxic conditions. • Cabaços Fm organic-rich rocks were deposited under oxic to suboxic conditions. [ABSTRACT FROM AUTHOR]

The investigation of the relationship between paleoenvironmental conditions and distribution and relative abundance of specific saturated and aromatic hydrocarbons was the main objective of this study, thus marking the parameters, which were most sensitive to environmental changes. Insights on the type, generative potential, and maturity of organic matter (OM), as well as paleoclimate conditions, along with the reconstruction of depositional settings of the northwest part of the Toplica basin (Serbia), were provided. Organic petrographic, palynofacies, organic geochemical, mineralogical, and XRF analyses were carried out to investigate 40 sediment samples of the Prebreza and Čučale sedimentary units. Investigated samples were deposited in the saline and anoxic environment, under semi-arid to semi-humid/humid climate conditions, along with the constant inflow of volcanoclastic material. The predominance of δ-methyltrimethyltridecil chroman (δ-MTTC) within euxinic portions of the stratified water column was associated with an increase in salinity, which was noticed for sediments of the Prebreza unit. Sediments from this stratigraphic unit showed a higher contribution of algae precursor, whereas sediments of the Čučale unit suggested higher participation of microbiologically reworked OM. Most of the samples contained oil-prone kerogen type II. Maturity of the OM for sediments of the Prebreza unit ranged from immature to early-mature, while for samples of the Čučale unit varied from early-mature to mature stages. Distribution of hopane biomarkers typical for crude oil indicated that depth of 1 km was a boundary for the genesis of thermodynamic, more stable compounds. A significant portion of semifusinite was correlated with the paleofire event, which affected the distribution of n -alkanes. The high production of hydrocarbons was related to volcanic activity. Parameters, which proved to be highly susceptible at the stratigraphic boundary between the Prebreza and Čučale units, were C-value, S/H, α-MTTC, δ-MTTC, β-/γ-MTTC, and (1,3- + 1,6-)/(1,4 + 1,5-DMC), respectively. • The Prebreza and Čučale units are deposited in two distinct paleoenvironments. • Most of the samples contain oil-prone kerogen type II and cover a wide maturity span. • Analcime in the borehole is related to the constant inflow of volcanoclastic material. • δ-MTTC predominance is related to the higher salt content in the Prebreza unit. • Significant alteration of some parameters is observed at the stratigraphic boundary. [ABSTRACT FROM AUTHOR]

The Early Toarcian Oceanic Anoxic Event (T-OAE) is characterised by major palaeoenvironmental and palaeoceanographical changes (ocean anoxia, global warming, ocean acidification, among other), and a severe perturbation of the global carbon cycle. Although widespread oceanic anoxia was a significant control on the occurrence of organic-rich facies during the T-OAE in several locations of the northern Tethyan margin, the effects of anoxia, oceanic productivity, and dilution are poorly understood in other worldwide locations, such as the southern Tethyan and Iberian margins. In this study, we report new geochemical [total organic carbon (TOC), total sulphur (TS), total carbonate content (CaCO 3), δ13C from kerogen isolates (δ13C Kerogen)], palynofacies and thermal maturation data from the Upper Pliensbachian–Lower Toarcian successions in La Cerradura and Fuente Vidriera, External Subbetic domain, Betic Cordillera (SE Spain). The obtained results indicate that these successions have low TOC contents (~ 0.3 wt.%), with TOC reaching up to 0.46 wt.% around the Polymorphum–Serpentinum ammonite zone boundary in La Cerradura. δ13C Kerogen negative carbon isotope excursions (CIE) are observed at the base of the Polymorphum Zone, the Pliensbachian–Toarcian Event (Pl-Toa), and base of the Serpentinum Zone (T-OAE). Overall, the low maturity kerogen assemblages are dominated by terrestrial OM and with a minor marine component. Small increments in terrestrial OM, non-opaque phytoclasts, and palynomorphs are observed just before and during the T-OAE in the studied area. During the Early Toarcian, in the External Subbetic domain, accumulation and preservation of OM was low and with a significant terrestrial contribution, similarly to other locations around the southern margins of Iberia and Tethys. The dominance of the opaque phytoclast subgroup, the occurrence of Classopollis , and the relatively more positive δ13C of terrestrial kerogen suggest that OM was mostly sourced from an area characterised by a semi-arid climate (i.e. with pronounced arid periods) during most of the Polymorphum Zone. The T-OAE negative CIE is accompanied by an increase in terrestrial OM, with a slight increase in the non-opaque phytoclast subgroup and terrestrial palynomorph subgroup. The increase of non-opaque phytoclast and terrestrial palynomorphs are in line with the posited enhancements of the hydrological cycle and export of terrestrial OM into marine environments during the T-OAE. This study suggests a link between 13C fractionation during photosynthesis in C3 plants and climate during the Early Toarcian. This link suggests coupling of the water and terrestrial carbon cycles before and during the T-OAE. • Early Toarcian sediment successions of the External Subbetic are mainly organic matter lean. • The studied palynofacies assemblages suggest a dominantly semi-arid climate. • During the T-OAE, an increase in land plant-derived organic matter is observed. • A link between 13C fractionation during photosynthesis in C3 plants and climate during the Early Toarcian is suggested here. [ABSTRACT FROM AUTHOR]