Paris Basin Research Articles

Microstructures and physical properties in carbonate rocks: A comprehensive review

Abstract Carbonate rocks are well-known to be tremendously heterogeneous. They mainly consist of component particles (from biological and non-biological origin) embedded in a lime-mud matrix and/or in a cement (composed of even smaller particles). The size, shape, density and spatial arrangement of those particles, alongside with natural fractures and cracks (although those are certainly not exclusive to carbonate rocks), define a microstructural pattern that is known to have a great influence on rock physical properties. Thus, to understand carbonate rock systems at large scales (formation, reservoir …), geophysicists have to study them at the pore scale, hoping to resolve the so-called “upscalling” problem. With this in mind, unravelling and identifying the relations between physical properties and carbonate rock microstructures is paramount for a global comprehension of a carbonate rock system. Since the late nineties, several research groups and authors have worked on documenting and providing significant insights into the microstructural parameters controlling the physical response of several rock properties (porosity, permeability, electrical conductivity, elastic, seismic and mechanical properties …) in carbonates. This article proposes a review of this specialized literature, from the early and recent contributions in rock physics, with emphasis on the recent studies on carbonate rocks from the Paris basin.

Onshore and offshore evidences for four abrupt “warming” episodes during MIS 6 at the westernmost tip of continental Europe: did they control the migrations of Neanderthals?

The total shell production typical of the Pupilla association in the onshore site of Nantois (Brittany, France) evidenced for the first time four brief, abrupt, warm and humid episodes during the Upper Saalian (MIS 6) loess deposition. These “warming” events were also found in the marine deposits of the Celtic Sea (MD03-2692 core). Comparison with the variations of the sea-level, show that the “warming” episodes were not only of regional interest but corresponded to global events ruled by precession and insolation cycles. Other comparisons with biomarker records (mollusсs, charcoal and rodents) of the Paris Basin (Villiers-Adam) and Jersey Island (La Cotte de Saint Brolade) confirm the existence of these warmer events. Tentative correlations with the discontinuous Neanderthal dwelling phases recorded in Brittany suggest that these populations were mainly (only?) present in Westernmost Europe during the warmer episodes.

Constraints on the duration of the early Toarcian T-OAE and evidence for carbon-reservoir change from the High Atlas (Morocco)

Abstract The Toarcian oceanic anoxic event (T-OAE, ~183 Ma) marks a geologically brief and severe global warming, associated with a profound perturbation in the global carbon cycle. The carbon cycle perturbation has been documented worldwide in marine and continental sedimentary records with a pronounced negative carbon isotope excursion (CIE) in the long-term δ13C profile. However, the cyclostratigraphically inferred duration of the CIE, which was mainly derived from the Paris (France) and Lusitanian (Portugal) basins, remains controversial, resulting in two notably different estimates of 300–500 and 900 kyr. Here, we present an early Toarcian cyclostratigraphic record from the High Atlas in Morocco (Talghemt section), based on high-resolution δ13C and %CaCO3 data, which capture the Pliensbachian-Toarcian (Pl-To) transition event and the T-OAE, and strongly correlate to previous δ13C key records. Orbital tuning based on the short and long, stable 405 kyr (g2–g5) eccentricity cycles, provides a duration of ~400 to ~500 kyr for the T-OAE. This duration is very close to that previously inferred from the Sancerre Core in the Paris Basin (300 to 500 kyr), and similar to that recently revised from the Peniche section (Lusitanian Basin, Portugal) (~472 kyr). In addition, the 405 kyr%CaCO3 timescale at Talghemt calibrates high-frequency δ13C variations at the Pl-To transition and the initiation part of the T-OAE to the obliquity cycle band, thus concuring with previous studies for obliquity forcing during these time intervals. The 405 kyr calibrated O1 obliquity period (~30 kyr) is shorter than the astronomically predicted one (~35 kyr), hence supporting the hypothesis of shortened obliquity periods during the Early Jurassic, and providing constraints on Earth’s tidal dissipation factor during this geologic epoch. Finally, a remarkable phase change between %CaCO3 and δ13C orbitally paced cycles is observed for the first time at the T-OAE, suggesting a change in the carbon reservoir in relation with volcanically released greenhouse gases and major carbonate crisis. However, this phase shift is not observed at the Pl-To event implying different causal mechanisms on the carbon cycle perturbation between the Pl-To and T-OAE events.

New paroxyclaenid mammals from the early Eocene of the Paris Basin (France) shed light on the origin and evolution of these endemic European cimolestans

We present new species of an enigmatic family of mammals, which is endemic to Europe, the Paroxyclaenidae: Merialus bruneti sp. nov., Fratrodon tresvauxi gen. et sp. nov., Paraspaniella gunnelli gen. et sp. nov., and Sororodon tresvauxae gen. et sp. nov. The fossils described come from six localities of the Ypresian of the Paris Basin (France): Pourcy (MP7), Mutigny, Avenay, Condé-en-Brie (MP8 + 9), Grauves and Prémontré (MP10). They allow the description of three new genera and four new species belonging to the subfamilies Merialinae and Paroxyclaeninae. Two of these new species represent the earliest occurrence of each subfamily. Fossils from Mutigny, Avenay and Condé-en-Brie indicate that merialines were more abundant than paroxyclaenines during the Ypresian. Surprisingly, merialines disappeared from the fossil record at the end of the Ypresian – the youngest records are close to MP10 – while the paroxyclaenines were present in Europe until the end of the middle Eocene. Based on comparison with the data presently available for European mammals during the Ypresian, we suggest the existence of two periods of faunal turnover that must be more extensively studied in the future in order to be fully characterized: the ‘Intra-Ypresian Mammal Turnover’ and the ‘Ypresian–Lutetian Mammal Turnover’. Finally, because the oldest paroxyclaenids appear morphologically closer to cimolestids such as Procerberus than to pantolestans, it is suggested that similarities between paroxyclaenids and pantolestans could be due to convergence. http://zoobank.org/urn:lsid:zoobank.org:pub:8A3B21A0-6945-4CE4-975C-402736E92C51

Overall stability in the genetic structure of a Zymoseptoria tritici population from epidemic to interepidemic stages at a small spatial scale

Subpopulations of the wheat pathogen Zymoseptoria tritici (26 sample groups composed of 794 isolates) were collected in two nearby wheat fields in the Paris basin, during both epidemic and inter-epidemic periods of three successive years (2009–2013). In addition to the type of inoculum (ascospores vs. pycnidiospores), the alternative presence of wheat debris allowed taking into account its putative origin (local vs. distant). We used a molecular epidemiology approach, based on population genetic indices derived from SSR marker analysis, to describe putative changes in the structure and genotypic diversity of these subpopulations over 3 years, at a spatiotemporal scale consistent with epidemiological observations. Genetic structure was broadly stable over time (within and between years) and between fields, however with weak population differentiation over time. All subpopulations displayed very high diversity and the occurrence of regular sexual reproduction was confirmed in the two fields. A significant increase of the MAT1–1/MAT1–2 ratio was observed over the course of the epidemics. This original finding suggests a competitive advantage of MAT1–1 strains consistently with their greater pathogenicity reported in the literature and may reveal undescribed adaptation. Finally, we found that the period, the type of inoculum and its putative origin had little effect on the short term evolution of the local population of Z. tritici. Fungal population size and diversity are apparently large enough to prevent genetic drift at this fine spatiotemporal scale, and more likely short distance migration contributes strongly to the stabilization of genetic diversity among and within plots.

Evidence of multiple thermokarst events in northeastern France and southern Belgium during the two last glaciations. A discussion on ‘Features caused by ground ice growth and decay in Late Pleistocene fluvial deposits, Paris basin, France’ ( )

The past thermokarst activities in valleys of northern France and Belgium covered the Upper Weichselian and the Upper Saalian periods. To develop in western Europe, thermokarst first requires an accumulation of ground ice close to the surface progressively stored along the glacial-time permafrost aggradation: it is regionally uncommon during the early glacials, especially on the plateau, but frequent during the Upper Pleniglacials in valleys. These features mostly relate to various frost mounds created by injection and segregated ices. The role of ice wedges is really very limited in this zone of southern extent of the European palaeo-permafrost on plateau and terraces. Thermokarst events are mostly susceptible to occur during the coldest part of the glacial. With a more progressive warming or a retrogressive thermokarst triggered by erosion, as in Arctic today, deformations are more gradual, in direct relation with the rheological properties of the sediments and usually local drainage. They are in concurrence with the vegetation dynamic that will limit its expression. Thermokarst events are in first order orbitally forced under control of a maximum insolation and a minimum in precession, as well as during the Weichselian and the Saalian. They are moreover, associated with abrupt warming transmitted by Dansgaerd Oeschger events. Snowiness and mild winter temperatures are probably the main triggers for thermokarst activity as of today. Other events can be triggered by solar activity as at 20 ka or perhaps enhanced by major ash splay as during the MIS 6b Zeiffen interstadial. Thermokarst events are usually followed on the continent by a reorganization of the rivers from braided to meandering systems.

Uniaxial compressive strength measurements of limestone plugs and cores: a size comparison and X-ray CT study

In many geo-engineering fields, the uniaxial compressive strength (UCS) of a rock material is the parameter most commonly used to define a rock’s mechanical strength. Several international standards have been developed for determining this value, which require the tested material to have certain minimum dimensions and shapes. In many applications, however, sample material is limited. Therefore, this study investigates the possibility of determining the UCS on rock plugs smaller than the minimum dimensions in the most common standards. The materials investigated are four different depositional limestones from the Paris Basin which are often used as building material in France and Belgium. Results from UCS tests in a small-scale uniaxial compressive device are compared to standard-sized tests according to the governing international standards. The results show that the strength determined on the small-scale plugs is very similar to the UCS determined on standard-sized cores. Using high-resolution X-ray computed tomography, it was possible to investigate the failure modes of the small-scale plugs and link them to their internal rock fabric. Obtaining a three-dimensional visualization provides valuable insights into the origin of the variability in the UCS measurements in small-scale plugs.

3D seismic for design and derisking of dual geothermal boreholes in sedimentary sequences and new prospects in the Paris Basin (Adapted methodology using petroleum industry techniques)

The use of existing geological and structural maps, previous 2D seismic profiles, boreholes and correlation models between these data is sufficient to understand basin structure and thermal systems on a regional scale. However, this is not sufficient on a scale of a geothermal site to be sure of the hydraulic connectivity (or of the presence of a permeability barrier) between two boreholes 1.5 or 2 km apart.To ensure that there is enough hydraulic connectivity, it i s necessary to understand the controls on the network of fractures which affects the aquifer (fracture permeability) and the physical properties of the rock, namely the porosity and clay content in order to obtain a matrix permeability.The latest generation of broadband (six octaves) 3D seismic reflection will provide the following information: the similarity attribute will give an accurate structural map of the fault network at the seismic resolution and, in many cases, at a higher resolution than seismic; seismic velocity anisotropy analysis techniques will make it possible to visualize a 3D volume of information on the fracture network [Michelet al.(2013) Application of Azimuthal Seismic Inversion for Shale Gas Reservoir –Proceedings of the 11th SEGJ International Symposium, Yokohama]; acoustic impedance inversion or petrophysical inversion techniques will predict the porosity throughout the whole volume of the aquifer from a porosity log recorded in a pilot-hole. It allows a real 3D mapping of predicted porosity inside the aquifer much more reliably than from modelling alone.These seismic techniques were initially developed for petroleum exploration and development. They have rapidly progressed throughout the last decade, both in acquisition, processing and interpretation with new methodologies and high-performance softwares. They are efficient for modelling reservoirs to be produced.And, consequently, they can be used for geothermal applications as data to design dual deviated drillings with horizontal drains in carbonate and clastic reservoirs – not only for new projects, but also to revisit old ones to improve their performance or develop another reservoir.Broadband 3D seismic will secure the exploration of Triassic sandstones which stay an interesting prospect for deep geothermal projects.New prospects are proposed in the Paris Basin: Regional faults overlap the substratum. Inside faulted zones, hydrothermal circulations arriving by convection at the top of granitic basement could be geothermal objectives, as in the Alsace Upper Rhine Graben.A production pilot site is suggested to test superimposed aquifers and a regional fault and, at the same time, two different architectures of boreholes doublets: horizontal drains for aquifers and deviated wells for crossing a regional fault.The first site that will use this approach could be instrumented and used as an experiment with a small addition of measurements and sensors, thus becoming a showcase for geothermal energy in France. The objective of this experiment would be to determine the transit time, the heating time of the re-injected water and the circulation speed to define the optimal direction, spacing and length of drains, and also, to realize the thermal modelling of the site for different options.

Perspectives sur l’étude des productions lithiques simples au Néolithique : le cas de la culture Blicquy/Villeneuve-Saint-Germain par le prisme du site de Vasseny (Aisne)..

Perspectives sur l’étude des productions lithiques simples au Néolithique : le cas de la culture Blicquy/Villeneuve-Saint-Germain par le prisme du site de Vasseny (Aisne)..

Occupations humaines et chronostratigraphie du gisement pléistocène d’Illiers-Combray (Eure-et-Loir, France) De nouveaux éléments pour le SIM 5b

Between 2012 and 2015, five successive archaeological campaigns were led by the Department of archaeology of Eure-et-Loir, on the Illiers-Combray plateau, 1 km to the east of the river Loir. Middle Palaeolithic remains were discovered in a Pleistocene loess-palaeosoils sequence, extending over an area of more than 10 km ² . This Early Weichselian site constitutes a major discovery, due to the good preservation of the artefacts and the sparse data in the south-west of the Paris basin. During the archaeological survey, trenches were dug down to the bedrock every 25 m to 50 m, which revealed lithic remains over the entire research area, while neither bones nor organic remains were preserved due to the low pH value of the soils. The geoarchaeological approach combines sedimentology, micromorphology and luminescence dating (OSL, post-IR IRSL, TL) of sediments and burned flint artefacts. Lithic artefacts were found isolated or in clusters of dozens of pieces at a depth comprised between 0.70 m and 2 m. Three main sectors were identified. The sector n° 1, situated to the north-east of the town, comprises of 59 lithic artefacts in small clusters of about 10 pieces per square meter over an area of 4500 m ² area. The sector n° 2, 500 m to the south, delivered 261 artefacts spread over an area of 3.6 ha. The third sector, covering an area of 0.4 km ² , is the largest of the three sectors and is located to the south-east of the two other areas. 186 lithic artefacts were found in this area. The Pleistocene loess-palaeosoil sequence is homogeneous and well preserved on the plateau. It covers at least three glacial-interglacial cycles (Saalian, Eemian and Wechselian) and can be divided into 15 units. At the base, the Saalian strata (unit 11 to 15) are above the “ argile à silex” tertiary formation (unit 16). The OSL age of the unit 11 is 218.6 ± 49.6 ky. Saalian strata are marked by huge ice wedges and hydromorphy. The Eemian strata show a well preserved pseudomorph of an ancient tree windthrow (unit 9) located in a luvisol (unit 8 and 10). OSL dating of the unit 10 gives 121.0 ± 15.7 ky. The Early Weichselian strata are comprised of three units 7.1, 7.2 and 7.3. The majority of the artefacts is contained in the unit 7b, which is rich in ferro-manganic nodules. However, some artefacts were also found in the 7a and 7c units, as well as in the ice wedges which cut through the Early Weichselian strata. The top of the sequence is characterised by decarbonated loess deposits in which a luvisol has developed. The lithic material is in excellent condition and numerous refi ttings testify a good preservation within the archaeologi-cal layers. The analysis of these remains suggests a concomitance of several operating production chains, to manufacture fl akes, blades and points as well as an operating chain for bifacial shaping. The identifi ed production methods are convergent unipolar, parallel unipolar, Levallois and discoid debitage. However, tools made out of fl akes are rare. They consist of side scrappers and retouched artefacts. Two burned artefacts from unit 7.2 were dated by TL at 88.9 ± 6.9 ky and 89.7 ± 6.9 ky, which place the lithic industry in the MIS 5b. The preliminary results shot that the site constitutes a new reference for the Pleistocene and the Middle Palaeolithic of the Centre and the North of France, in addition to the reconstruction of the palaeoenvironmental and archaeological history of this area. Finally, the extensive excavation could become important in reconstructing Middle Palaeolithic history, since the site itself is located on the divide between the watersheds of the Seine and the Loire and, thus, in a key area for understanding the cultural palaeogeography of the Neanderthal populations.

Мировые тенденции в развитии геотермальной энергетики. Часть 1. Геотермальные ресурсы по регионам мира

The article provides an overview of materials on the use of geothermal resources over regions of the world. The dependence of efficiency of using geothermal resources on the geophysical and geographical parameters of each region is shown. We present data on the countries where geothermal energy is developing most successfully and for what purposes it is used. The leaders are here the United States, the Philippines, Mexico, Indonesia, and New Zealand. All these countries are located in the areas of present-day volcanism, within the “Fiery Ring”, where the heat carrier has high parameters and is available on the Earth's surface, where the cost of building a geothermal power plant is minimal, and the prime cost of energy is competitive in the energy market. It is emphasized that geothermal energy is used very little on the global scale: the share of electricity generated from geothermal resources is only 0.5%. It is produced only in 24 countries. The direct use of geothermal heat is much more wide-spread: for space heating, including centralized heat supply, for and pools, greenhouses, air conditioning, for heating open ground, and pavement, in industrial processes, for melting snow and other purposes. For example, in the capital of China, Beijing, about three hundred wells were drilled to a depth of about 3 kilometers. Water with a temperature up to 70 °C flows from them and is used for central heating of high-rise buildings and for heating greenhouses. In Iceland, owing to geothermal heat, 90% of the country's heating capacity needs are met. Almost half of the volumes of geothermal energy are spent for heating and hot water. In the Paris basin, there are 37 circulation systems, including 50 installations for centralized heat supply. Heat is also supplied to greenhouses and fish farms. In 2007, a new draft of the circulation system for heating the Orly airport in Paris was implemented. In the vicinity of Paris, 170 thousand houses are heated by 33 geothermal plants.

Microbial and Geochemical Investigation down to 2000 m Deep Triassic Rock (Meuse/Haute Marne, France)

In 2008, as part of a feasibility study for radioactive waste disposal in deep geological formations, the French National Radioactive Waste Management Agency (ANDRA) drilled several boreholes in the transposition zone in order to define the potential variations in the properties of the Callovo–Oxfordian claystone formation. This consisted of a rare opportunity to investigate the deep continental biosphere that is still poorly known. Four rock cores, from 1709, 1804, 1865, and 1935 m below land surface, were collected from Lower and Middle Triassic formations in the Paris Basin (France) to investigate their microbial and geochemical composition. Rock leachates showed high salinities ranging from 100 to 365 g·L−1 NaCl, current temperatures averaging 65 °C, no detectable organic matter, and very fine porosity. Microbial composition was studied using a dual cultural and molecular approach. While the broad-spectrum cultural media that was used to activate microbial communities was unsuccessful, the genetic investigation of the dominant 16S rRNA gene sequences revealed eight bacterial genera considered as truly indigenous to the Triassic cores. Retrieved taxa were affiliated to aerobic and facultative anaerobic taxon, mostly unknown to grow in very saline media, except for one taxon related to Halomonas. They included Firmicutes and α-, β-, and γ-Proteobacteria members that are known from many subsurface environments and deep terrestrial and marine ecosystems. As suggested by geochemical analyses of rocks and rock leachates, part of the indigenous bacterial community may originate from a cold paleo-recharge of the Trias aquifer with water originating from ice melting. Thus, retrieved DNA would be fossil DNA. As previously put forward to explain the lack of evidence of microbial life in deep sandstone, another hypothesis is a possible paleo-sterilisation that is based on the poly-extremophilic character of the confined Triassic sandstones, which present high salinity and temperature.

ICHTHYOSAURIA TEETH OF CRETACEOUS DEPOSITIONS IN UKRAINE

During early and late Cretaceous wide range of large reptiles-carnivores of Reptilia class, Ichthyopterygia subclass and Ichthyosauria order inhabit basins and bays of warm-water shallow epiсontinental seas situated in the separated northern coast of Mezotethys. Among Ichthyosauria fossils found are some fragments of skeletons, separate findings of skull fragments preserved to various extent, vertebrae and teeth which findings are known in Greenland, southwest of Great Britain, Parisian basin, Northern Apennines (Italy), Annopole (Poland) and Volga region (Russia). The findings of ichthyosauria teeth and vertebrae (Kaniv, Malyn, Transnistria) make it possible to fill the gap (region) between Western Europe and eastern area of the East European platform. Fossils of the latest and youngest in age ichthyosaurus (Platypterygius sp. and Platypterygius? sp.) found in Ukraine are presented by phosphatized vertebrae and teeth preserved to different extent. Ichthyosauria fossils are sampled from glauconite quartz sands of Albian and Cenomanian (Kaniv, Middle Transnistria) and basal depositions of sedimentary cover (Malyn). Lithological and stratigraphic characteristics of ichthyosauria teeth locallities of Cretaceous depositions in Ukraine are discussed.

Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: Application to Middle Jurassic carbonate reservoirs in the Paris basin, France

AbstractIn recent years stylolites, which are rough dissolution surfaces commonly found in carbonates, have been used for paleopiezometry estimates. The Stylolite Roughness Inversion Technique (SRIT) applied on sedimentary bedding-parallel stylolites (BPS) grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo-depth. This study reports the results of SRIT applied to a BPS population hosted in carbonate platform reservoirs of the Paris basin sub-surface (France). Middle Jurassic carbonates from two well cores from the depocenter and margin of the basin, for which the burial and thermal history are known, based on a thermally calibrated 3-D basin model, were analyzed. By defining a consistency criterion and using two signal treatment methods, we propose a new approach to select which BPS can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates, which then can be converted into maximum burial depth. The study of a BPS population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded. Especially suture and sharp peak BPS are better suited to estimate the real maximum depth, whereas seismogram pinning BPS record preferentially intermediate depths. Median values of maximum depth derived from our data set (1300 and 1650 m for the margin and depocenter cores, respectively) are in line with maximum burial estimates provided by conventional basin modeling (1450 and 1800 m, respectively), thus showing that SRIT is a standalone robust depth gauge in sedimentary basins, provided sample selection and data treatment are carried out in a rigorous and thoughtful manner.

Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, eastern France and western Switzerland)

The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhône Formation and record stepwise environmental change on the innermost platform, which was strongly influenced by the nearby landmass. From the latest Barremian onward, sedimentation progressively changed from: i) predominantly oncoidal and detrital charophyte-rich marly limestones; to ii) heterozoan marly limestones and marls; followed by iii) detrital sediments interspersed with numerous phosphatic conglomerates. These changes are linked with the onset of the latest Barremian Taxy Episode and with the following oceanic anoxic episodes (OAE's) 1a to d in the neighbouring basins. The sedimentary changes are associated with sedimentary sequences which formed during 2nd-order transgressions, and which express the effect of sea level fall followed by drowning events. The presence of a rich ammonite-fauna allowed a precise biostratigraphical dating of these events during the latest Barremian to Cenomanian time interval.

An emerging thermochronometer for carbonate-bearing rocks: ∆47 /(U-Pb)

Research Article| November 09, 2018 An emerging thermochronometer for carbonate-bearing rocks: ∆47 /(U-Pb) Xavier Mangenot; Xavier Mangenot * 1IFP Energies nouvelles, 92852 Rueil-Malmaison Cedex, France2Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France *E-mail: xavier-mangenot@club.fr Search for other works by this author on: GSW Google Scholar Marta Gasparrini; Marta Gasparrini 1IFP Energies nouvelles, 92852 Rueil-Malmaison Cedex, France Search for other works by this author on: GSW Google Scholar Axel Gerdes; Axel Gerdes 3Institute of Geosciences, Goethe University, 60438 Frankfurt, Germany Search for other works by this author on: GSW Google Scholar Magali Bonifacie; Magali Bonifacie 2Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France Search for other works by this author on: GSW Google Scholar Virgile Rouchon Virgile Rouchon 1IFP Energies nouvelles, 92852 Rueil-Malmaison Cedex, France Search for other works by this author on: GSW Google Scholar Geology (2018) 46 (12): 1067–1070. https://doi.org/10.1130/G45196.1 Article history received: 24 May 2018 rev-recd: 10 Oct 2018 accepted: 22 Oct 2018 first online: 09 Nov 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Xavier Mangenot, Marta Gasparrini, Axel Gerdes, Magali Bonifacie, Virgile Rouchon; An emerging thermochronometer for carbonate-bearing rocks: ∆47 /(U-Pb). Geology 2018;; 46 (12): 1067–1070. doi: https://doi.org/10.1130/G45196.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Assessing the thermal evolution of sedimentary basins is critical for understanding the origin of natural resources (including ores, geothermal fluids, or hydrocarbons) and for deciphering larger-scale tectonic and geodynamic evolutions. Modern reconstructions of past subsurface temperatures mostly rely on thermochronometers that are not applicable to carbonate rocks [e.g., fission-track and (U-Th)/He analyses]. Here, by coupling carbonate clumped isotope (∆47) thermometry and laser ablation U-Pb geochronology on a complete paragenetic sequence, we demonstrate the applicability of an emerging thermochronometer for carbonate bearing-rocks. Paired ∆47 and U-Pb data were obtained for calcite and dolomite phases precipitated in a Middle Jurassic carbonate hydrocarbon reservoir of the Paris Basin depocenter (France). The absolute thermochronological data allow the precise reconstruction of the thermal history of these rocks: from shallow burial temperatures (∼40 °C), occurring in the Late Jurassic, toward a progressive burial and heating stage (up to 87 °C) during the Cretaceous, followed by a cooling stage (down to 69 °C) during the Tertiary uplift of the basin. The inferred time-temperature path based on Δ47/(U-Pb) data is mostly consistent with the thermal scenario independently deduced from organic maturity indicators from the underlying Lower Jurassic shales. The Δ47/(U-Pb) thermochronological data also highlight a thermal anomaly during Aptian–Albian time that requires revisiting the accepted timing for hydrocarbon migration in the Middle Jurassic reservoir carbonates. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

3D Numerical Modelling and Sensitivity Analysis of the Processes Controlling Organic Matter Distribution and Heterogeneity—A Case Study from the Toarcian of the Paris Basin

The active debate about the processes governing the organic-rich sediment deposition generally involves the relative roles of elevated primary productivity and enhanced preservation related to anoxia. However, other less spotlighted factors could have a strong impact on such deposits, e.g., residence time into the water column (bathymetry), sedimentation rate, transport behavior of organo-mineral floccules on the sea floor. They are all strongly interrelated and may be obscured in the current conceptual models inspired from most representative modern analogues (i.e., upwelling zones and stratified basins). To improve our comprehension of organic matter distribution and heterogeneities, we conducted a sensitivity analysis on the processes involved in organic matter production and preservation that have been simulated within a 3D stratigraphic forward model. The Lower-Middle Toarcian of the Paris Basin was chosen as a case study as it represents one of the best documented example of marine organic matter accumulation. The relative influence of the critical parameters (bathymetry, diffusive transport, oxygen mixing rate and primary production) on the output parameters (Total Organic Carbon, and oxygen level), determined performing a Global Sensitivity Analysis, shows that, in the context of a shallow epicontinental basin, a moderate primary productivity (>175 gC·m−2·year−1) can led to local anoxia and organic matter accumulation. We argue that, regarding all the processes involved, the presence and distribution of organic-rich intervals is linked as a first-order parameter to the morphology of the basin (e.g., ramp slope, bottom topography). These interpretations are supported by very specific ranges of critical parameters that allowed to obtain output parameter values in accordance with the data. This quantitative approach and its conclusions open new perspectives about the understanding of global distribution and preservation of organic-rich sediments.

Response to the discussion by Van Vliet-Lanoë et al. of the paper ‘Features caused by ground ice growth and decay in Late Pleistocene fluvial deposits, Paris Basin, France’ (Bertran et al., 2018, Geomorphology 310, 84–101)

The response by Van Vliet-Lanoë et al. to our paper on potential thermokarst features in Pleistocene alluvial deposits from the Paris Basin (France) presents inconsistencies that we consider here successively. These are (1) the map of the maximum extent of Pleistocene permafrost in France, (2) the genesis of liquefaction and fluidization structures in periglacial environments, (3) the origin of thermokarst lakes and recumbent folds, (4) the depositional context of sandy units, and (5) the age of the studied deposits. All structures result from the interplay between (1) the growth and degradation of ice wedges, which are responsible for the development of a mound-like topography (badland thermokarst reliefs) on the edge of the alluvial terrace and from the initiation of ponding elsewhere on the terrace, (2) the degradation of lithalsa that developed later in the lacustrine deposits. The sequence was dated confidently to the Late Weichselian.

Diffusion of organic anions in clay-rich media: Retardation and effect of anion exclusion

The transport of emerging organic contaminants through the geosphere is often an environmental issue. The sorption of organic compounds slows their transport in soils and porous rocks and retardation is often assessed by extrapolation of batch experiments. However, transport experiments are preferable to strengthen migration data and modelling. In this context, we evaluated the adsorption of various organic acids by means of through-diffusion experiments in a sedimentary clay-rich rock (Callovo-Oxfordian, East of Paris Basin, France). A low diffusivity of organic anions was quantified with effective diffusion coefficients, De, ranged between 0.5 and 7 10−12 m2 s−1. These values indicated an organic anion exclusion. As for chloride, the porosity accessible to organic anions was lower than that of water: εa(organic anions) < ε(water). The partial exclusion of organic anions from rock porosity was linked to both charge and size effects. A significant retardation was observed for organic anions such as oxalate, citrate or α-isosaccharinate. Yet, retardation measured by diffusion experiments was significantly lower than expected from batch experiments on crushed samples. An empirical correction factor is proposed to account for a possible decrease of retardation with accessible porosity of diffusing solute. This feature has significant implications for the estimation of migration parameters of organic compounds in the environment.

New Species of Crassatellidae (Bivalvia) from the Middle Eocene of Ukraine

Three new species of Crassatellidae: Crassatella ballista sp. nov., C. calva sp. nov., and Eucrassatella depulsoris sp. nov. from the Middle Eocene deposits of the western slope of the a quarry of the Ingulets Ore Mining and Processing Enterprise (Ingulets, Ukraine), which are correlated with the Lutetian Stage, are described. The study of valves of Crassatella parisiensis Orbigny, 1852 from the Middle Eocene deposits of the Parisian Basin has shown that it differs from the species C. illustris Berezovsky, 2004, which was previously described as a subspecies of C. parisiensis. The study of variation of Crassatellidae provided substantiation of the species rank of C. artacosta Berezovsky, 2004, which was previously described as a subspecies of C. densicostata Berezovsky, 1998.