Temperature is a critical parameter in sedimentary basin evolution. Its distribution through time and space highly contributes to address complex geodynamic topics in different settings through realistic thermal history reconstructions. Conventional thermal modeling constraints derived from the inorganic and organic fraction of sedimentary rocks (vitrinite %Ro, apatite fission-tracks, fluid inclusions, etc.) can be affected by important limitations.
Moreover, fluids circulation in fault zones and sediments is often disregarded. In the last years new modelling approaches, innovative thermo-chronology proxies (carbonate clumped isotopes thermometry coupled with laser ablation U-Pb chronometry) as well as Raman and FT-IR on organic matter and biomarker studies have been widely used to overcome these pitfalls. Aim of the session is to provide a worldwide panorama on sedimentary basins whose geodynamic evolution has been constrained by merging conventional and brand-new calibration techniques and thermal modelling approaches. Contributions on different scale mechanisms, also dealing with uncertainties of fluids and technique validation are warmly welcome and would allow for discussion on technique development and presentation of new pilot data.

Co-organized by GD4/SSP1
Convener: Andrea SchitoECSECS | Co-conveners: Sveva Corrado, Marta Gasparrini, Dave Muirhead, Silvia Omodeo SalèECSECS
| Attendance Wed, 06 May, 10:45–12:30 (CEST)

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Session summary Download all presentations (45MB)

Chat time: Wednesday, 6 May 2020, 10:45–12:30

Chairperson: Sveva Corrado, David Muirhead, Andrea Schito, Silvia Omodeo Salè
D1162 |
Andrea Di Giulio, Chiara Nicola, Domenico Grigo, Paolo Scotti, Massimiliano Zattin, Chiara Amadori, Silvia Tamburelli, Alberto Consonni, and Andrea Ortenzi

Unravelling the time-space distribution of diagenetic events modifying the pore network of reservoir rocks is a classical task of hydrocarbon research. Nevertheless, it is not always easy to reach that picture, as it needs to constraint a number of variables driving that distribution along the geological history of sedimentary basins.

Here we present the results of an integrated study performed on 15 samples of Palaeozoic reservoir sandstones coming from 3 hydrocarbon wells in the Illizi Basin. In particular, the topic of debate that promoted this study is the possible thermal effect on the Illizi Basin reservoirs rocks of the Cenozoic magmatic activity occurred in Hoggar dome, south of the studied region, and in other sector of the basin as pointed out by several magmatic intrusions.

The study was performed by combining: i) the reconstruction of the relative diagenetic timing obtained by petrographic observations; ii) microthermometric analyses of fluid inclusions trapped in diagenetic minerals; iii) low-T thermochronology (both Fission tracks and U-Th/H analyses) on clastic apatite grains; iv) vitrinite reflectance analysis; v) geohistory analysis of sampled wells. These data were used to constrain different thermal models, focussing in particular to the possible evidence of a Tertiary thermal overprint.

The results of the study can be summarized as follows:

  • Several diagenetic minerals precipitated in the pore network of the studied rocks; among these, precipitation conditions for quartz, calcite, ankerite and to a minor degree feldspars were constrained through fluid inclusion microthermometric analyses;
  • All these phases precipitated in a relatively narrow range of temperatures nicely correlated with burial depth of samples, from fluids with quite homogenous salinity (78-113 °C and 9.2-14.5 NaCl eq. %) suggesting a relatively limited time in which most of cements precipitated;
  • The data on the thermal maturity of organic matter (vitrinite reflectance along the Mesozoic sequence, and vitrinite reflectance equivalent, mainly from chitinozoans, for the Silurian-Devonian sequence) seem to suggest a heating higher than the one currently observed. This may be compatible both with an episode of magmatic activity or with a late Cretaceous-Tertiary burial now eroded (in the wells studied, no more than 500-700m);
  • Thermochronology shows a continuous burial until temperatures compatible with those observed by vitrinite reflectance although a minor thermal episode (i.e. with a temperature variation of the order of 10°C) is allowed.

Based on this integrated data set, different thermal scenarios have been tested, excluding or including a Cenozoic additional heating, in order to estimate the effect of the adopted thermal model on the age of cement precipitation in the pore system of studied reservoir rocks.

How to cite: Di Giulio, A., Nicola, C., Grigo, D., Scotti, P., Zattin, M., Amadori, C., Tamburelli, S., Consonni, A., and Ortenzi, A.: DIAGENETIC HISTORY VS. THERMAL EVOLUTION OF PALAEZOIC RESERVOIR ROCKS IN THE ILLIZI BASIN (Algeria), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2386, https://doi.org/10.5194/egusphere-egu2020-2386, 2020.

D1163 |
Shaowen Liu and Liangshu Wang

Evaporitic salt is prevailed in marine sedimentary basins, and the discovered hydrocarbon reservoirs are generally associated with salt structures in the world; accordingly salt structures have attracted much attention from academic and industry during the past decade. Tarim Basin that locates in northwest China, is the largest marine sedimentary basin in China with great hydrocarbon resources potential. Previous studies of salt structures in this basin mainly focus on its strong sealing capacity and structural traps created by salt structures. However, besides its extreme impermeability and low viscosity, rock salt has another unique thermal properties, featured by a large thermal conductivity as high as 5~6 W/(m.K), usually 2~3 times greater than that of other common sedimentary rocks, but a relatively low radiogenic heat production. This strong contrast in thermal properties could change the evolving thermal regime and associated thermal history of the source rocks around salt bodies, but has not been understood well. Herein based on the theoretical models and interpreted salt bearing seismic profiles from the Kuqa Foreland Basin, northern Tarim Basin, we use the 2D finite element numerical experiments to investigate the impacts of salt structures on basin geothermal regime and associated hydrocarbon thermal evolution. Our results show that, owing to its high efficiency in heat conduction, the salt rocks would result in obviously positive temperature anomalies (3~13%) above the salt body and negative temperature anomalies (11~35%) in the subsalt, enhancing and restraining the thermal maturation of source rocks above and below the salt body, respectively. The amplitude and extent of geothermal effects of salt structures depend on the thermal conductivity, geometry, thickness and burial depth of the salt bodies. The thermally affected area around the salt body can be 2 time of salt radius laterally and 2~3 times of salt thickness vertically. Salt structures in the Kuqa Foreland Basin can prominently cool the subsalt formation temperature and accordingly reduce the thermal maturity (Ro) of Jurassic source rocks as much as 18%, enabling the source rocks to be still of gas generation other than over-mature stage as expected previously, which is favor for deep hydrocarbon preservation below salt. In particular, salt structures in the west and east Kuqa Foreland Basin show strong differences in their thickness, geometric pattern, burial depth and composition, the thermal effects of salt structures on thermal maturation of subsalt source rocks should differ accordingly, which is supported by the observed tempo-spatial variation of Ro for Jurassic source rocks in this basin. Finally, we propose that the geothermal effects of salt structures will be of great importance in the deep hydrocarbon resources potential assessment and exploration in marine sedimentary basins in China.

How to cite: Liu, S. and Wang, L.: Quantifying the Effects of Salt Structures on Source Rocks Thermal Evolution of the Marine Sedimentary Basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4584, https://doi.org/10.5194/egusphere-egu2020-4584, 2020.

D1164 |
Chiara Amadori, Antonio Langone, Mattina Marini, Reguzzi Simone, Barbara Carrapa, Matteo Maino, and Andrea Di Giulio

The Tertiary Piedmont Basin (TPB) in NW Italy represents an episutural basin developed since the Late Eocene in the retrobelt of the Western Alps and in the foreland of the Northern Apennine. During Oligo-Miocene time, up to 3 km-thick clastic deposits filled the basin recording the tectonics associated with the shift from the Alpine collisional thickening and the progressive NE-migration of the Apennine. The continental thickening was also accompanied by the opening of the Liguro-Provençal Basin and the drift of the Corsica-Sardinia block. Because of this key-position, the tectono-sedimentary and thermochronological history of the TPB has been the object of extensive investigations (Maino et al., 2013 and reference therein). However, several questions regarding its burial-exhumation history are still open. In order to define the thermal history of the source-sink system, we combined literature data with new detrital apatite fission-track analyses and zircon U-Pb dating from Upper Priabonian to Lower Miocene syn-tectonic deposits. Results from AFT analysis show: i) a single reset population at 24.8 ± 1.2 Ma (Late Chattian) in the lowermost Late Priabonian sample; ii) partially annealed apatite grains from Early Rupelian sample; iii) unannealed Late Rupelian-Miocene samples with AFT age populations spanning from Late Cretaceous to Late Oligocene in time. Data from the Ligurian Alps crystalline massifs report similar AFT cooling ages between 22.9 ± 5.3 - 24.0 ± 1.4 Ma. This, combined with our data, shows that the bottom of the TPB sequence experienced ~110 °C heating and subsequent cooling together with its nearby margin. The heating experienced by the basin combined with reconstructed sedimentary thickness (before the exhumation/cooling event) of ca. < 3 km, implies an elevated geothermal gradient of about 60 °C/Km, which is anomalous for a thickened orogenic crust. Furthermore, one sample from Upper Oligocene sedimentary rocks contains an AFT detrital population age (33.6 ± 2 Ma) consistent with a youngest U-Pb age peak of 33.6 Ma from co-magmatic zircon grains, which likely reflects the age of volcanites today buried under the Po Plain (Di Giulio et al., 2001). Detrital zircon U-Pb ages show two main populations at ca. 290 and ca. 460 Ma, which are expected products of a Variscan source now exposed in the Ligurian Alps and Southern Alps. Our new geo-thermochronological data overall suggests a distributed Oligocene thermal signal, the origin of which is discussed. Possible explanations are: 1) a > 3 km of focused erosion associated with tectonic deformation occurred in the TPB and nearby margin and/or 2) an anomalously high heat flow event driven by asthenospheric rise as a consequence of the Liguro-Provençal rifting.

Maino M., Decarlis A., Felletti F., Seno S. (2013) Tectono-sedimentary evolution of the Tertiary Piedmont Basin (NW Italy) within the Oligo–Miocene central Mediterranean geodynamics. Tectonics, 32, 593–619.

Di Giulio, A., Carrapa B., Fantoni R., Gorla L., Valdisturlo L. (2001) Middle Eocene to Early Miocene sedimentary evolution of the western segment of the South Alpine foredeep (Italy). Int. J. Earth Sci., 90, 534-548.

How to cite: Amadori, C., Langone, A., Marini, M., Simone, R., Carrapa, B., Maino, M., and Di Giulio, A.: Unexpected thermal history of a syn-collisional basin revealed by geo- and thermochronology: the case of the Tertiary Piedmont Basin (Western Alps, Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5815, https://doi.org/10.5194/egusphere-egu2020-5815, 2020.

D1165 |
| Highlight
Louis Howell, Stuart Egan, Bernard Besly, Graham Leslie, and Surika Sooriyathasan

As a consequence of 19th and 20th century coal mining, a vast quantity of subsurface data has been accumulated on Britain’s late Carboniferous Coal Measures and the basins in which they have accumulated. Here we discuss current understanding of the geological evolution of the British Isles during this period, as well as how these data can be repurposed as the UK seeks to reduce its greenhouse gas emissions.

It is widely assumed that Britain’s Coal Measures accumulated during a period of tectonically quiescent, thermally induced post-rift subsidence and that the lateral extent of the Variscan foreland in southern England and Wales was restricted. Burial history curves constructed from stratigraphic successions across the UK suggest, however, that during the late Carboniferous the UK was characterised by accelerated subsidence rates as far north as northern England and Scotland, beyond any perceivable flexure-induced foredeep. On local scales, seismic and borehole-based mapping shows that many individual depocentres were strongly influenced by syn-depositional faulting, folding and positive inversion. This influence is illustrated by repeated local unconformities within the late Carboniferous succession across England and Scotland as well as variable isochore thickness trends. We propose that this succession was influenced by a combination of both local tectonic controls and regional controls such as supralithospheric orogenic loading and sublithospheric dynamic loading. In this sense, we believe that the British Variscan foreland system, as the British Isles should be referred to as during the late Carboniferous, resembled a ‘broken’ foreland system such as that of Patagonia, South America.

Understanding the nature of Britain’s Coal Measures has gained renewed importance given the need to reduce carbon emissions and seek alternative sources of energy. Across the UK, there are a number of active projects aiming to harness latent heat from abandoned underground coalmines. In addition, coupled CO2 sequestration and enhanced coal bed methane recovery offers a further, if riskier, low carbon subsurface energy prospect. To aid deep geothermal exploration, subsurface data from northern England is being compiled in order to construct regional 3D geothermal models. Our models highlight hot areas within the subsurface more realistically than equivalent maps based on contouring around individual borehole temperature measurements that are skewed by sparsely distributed data points and, potentially, inaccurate measurements. Deep heat-producing granite bodies and the variable thickness of thermally resistive rock units, such as the Pennine Coal Measures Group, are highlighted as dominant controls on the distribution of deep geothermal energy in northern England.

How to cite: Howell, L., Egan, S., Besly, B., Leslie, G., and Sooriyathasan, S.: Repurposing Britain’s Coal Measures: insights from seismic and borehole-based mapping, and geothermal modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7205, https://doi.org/10.5194/egusphere-egu2020-7205, 2020.

D1166 |
Andrea Licciardi, Kerry Gallagher, and Stephen Anthony Clark

Vitrinite reflectance and apatite fission track) and borehole data (bottom hole temperature and porosi ty) for thermal history reconstruction in basin modeling.  The approach implements a trans-dimensional and hierarchical Bayesian formulation with a reversible jump Markov chain Monte  Carlo (rjMcMC) algorithm. The main objective of the inverse problem is to infer the heat flow history below a borehole given the data and a set of geological constraints (e.g. stratigraphy , burial histories and physical properties of the sediments).  The algorithm incorporat es an adaptive, data-driven parametrization of the heat flow history, and allows for automatic estimation of relative importance of each data type in the inversion and for robust quantification of parameter uncertainties and trade-offs. In addition, the algorithm deals with uncertainties on the imposed geological constraints in two ways. First, the amount of erosion and timing of an erosional event are explicitly treated as independent parameters to be inferred from the data. Second, uncertainties on compaction parameters and surface temperature histo ry are directly propagated 
into the final probabilistic solution.

How to cite: Licciardi, A., Gallagher, K., and Clark, S. A.: A Bayesian approach for thermal history reconstruction in basin modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13606, https://doi.org/10.5194/egusphere-egu2020-13606, 2020.

D1167 |
| Highlight
Nathan Looser, Herfried Madritsch, Marcel Guillong, Oscar Laurent, Stephan Wohlwend, and Stefano M. Bernasconi

During its late-stage evolution, the European Alpine orogen witnessed a northwest-directed propagation of its deformation front along an evaporitic basal décollement into the foreland. This resulted in the decoupling of the northern Alpine Molasse Basin from its basement and the formation of the Jura fold-and-thrust belt. Here, we present the first absolute age and temperature constraints on deformation along this major décollement by using combined carbonate U-Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and clumped isotope thermometry. We analyzed calcite veins associated with a secondary thrust fault branching off from the basal décollement in a deep borehole within the Swiss Molasse Basin providing evidence for three brittle deformation events related to Alpine contraction: Vein formation at ~14 Ma ago, thrust faulting with cataclasis ~13 Ma ago, and another vein formation event ~9 Ma ago. Clumped isotope data reveal vein calcite precipitation at temperatures of ~100 °C from fluids equilibrated with the host rock during all deformation intervals. These temperatures are in good agreement with temperature estimates from microfabrics of anhydrite mylonites in the basal décollement. Our data demonstrate that the propagation of Alpine deformation into its distal foreland occurred significantly earlier than previously inferred, at middle Miocene (Langhian) times at the latest, contributing to the debate about the late-stage geodynamics of the central Alps. The deformation sequence indicated by our results underpins fundamental kinematic models of viscous décollement-based foreland thrust belts. Beyond that, we demonstrate the potential of our methodological approach applied to foreland thrust systems in resolving the late-stage evolution of convergent orogens.

How to cite: Looser, N., Madritsch, H., Guillong, M., Laurent, O., Wohlwend, S., and Bernasconi, S. M.: Middle Miocene onset of thrusting along the basal décollement of the Jura Mountains: Evidence from carbonate U-Pb dating and clumped isotope thermometry, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18462, https://doi.org/10.5194/egusphere-egu2020-18462, 2020.

D1168 |
Anthea Arns, Frank Tomaschek, Edith Alig, Katrin Weber, Hubert Vonhof, Jan Fischer, Sebastian Voigt, and Thomas Tütken

The intra-mountainous Saar-Nahe Basin (SNB), SW Germany, a strike-slip-fault basin formed during the Variscian orogeny, was filled by a large freshwater lake system during the Early Permian. The SNB experienced intense syn- and post-depositional magmatic activity, resulting in a complex volcano-sedimentary sequence of magmatic intrusions, lava flows and tephra deposits intercalating in continental red beds and limno-fluvial sediments. Fossils preserved in white color are found in Permo-Carboniferous fluvio-lacustrine siliciclastic floodplain sediments with thin intercalated limestone banks, of the Remigiusberg Formation in the SNB. The oldest amniote fossil of Germany and other partly articulated tetrapod remains were recovered from it at the Remigiusberg quarry near Kusel (e.g., Fröbisch et al., 2011; Voigt et al. 2014). These terrestrial tetrapods were discovered together with aquatic vertebrate fossils in close proximity (< 5 m; within the contact aureole) to an underlying decameter thick sill of kuselite, an auto-hydrothermally altered andesite. We aim to assess the thermal and chemical impact of post-depositional contact metamorphism and hydrothermal activity associated with this sill on the bioapatite of vertebrate skeletal remains by characterizing the elemental, isotopic and mineralogical composition of these fossils. White-colored, likely hydrothermally altered teeth of the freshwater shark Lebachacanthus were analyzed and compared to shark teeth of the same species retaining their original black color, from contemporaneous unmetamorphosed lacustrine black shale deposits in the SNB.


In situ Electron Microprobe analysis and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) elemental profiles reveal distinct diagenetic histories for the black- and white-colored shark teeth. This is further supported by apatite 18O and 13C values, which indicate different secondary alteration by fluids for both facies. Raman spectroscopy and X-ray diffraction on bulk powder samples identify fluorapatite as the major mineral phase in all teeth. Apatite crystallinity of both dentin and enameloid is higher in white- than in black-colored fossils, consistent with crystallite growth due to thermal overprint of > 500 °C. For both, white- and black-colored shark teeth, LA-ICP-MS U-Pb analyses yield inconclusive data and unexpectedly young ages inconsistent with known ages of deposition or metamorphism.


We are currently analyzing the petrology of the kuselite to constrain the metamorphic evolution of sediments in the contact aureole by modelling. Additionally, heating experiments of modern bioapatite samples are performed to further constrain the alteration temperature. Altogether, these data will enhance our understanding of the particular thermometamorphic/hydrothermal conditions required to form white-colored, recrystallized vertebrate fossils in the context of the magmatic-metamorphic evolution of the SNB.



FRÖBISCH, J., SCHOCH, R.R., MÜLLER, J., SCHINDLER, T. & SCHWEISS, D.J. (2011): The oldest amniote from Germany: a sphenacodontid synapsid from the Saar-Nahe Basin. Acta Palaeontologica Polonica, 56: 113–120.


VOIGT, S., FISCHER, J., SCHINDLER, T., WUTTKE, M., SPINDLER, F. & RINEHART, L. (2014): On a potential fossil hotspot for Pennsylvanian-Permian nonaquatic vertebrates in Europe. Freiberger Forschungshefte, C548: 39–44.

How to cite: Arns, A., Tomaschek, F., Alig, E., Weber, K., Vonhof, H., Fischer, J., Voigt, S., and Tütken, T.: Metamorphosed Permian vertebrate fossils: geochemistry and mineralogy of “white” sharks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18533, https://doi.org/10.5194/egusphere-egu2020-18533, 2020.

D1169 |
Andrea Schito, Achraf Atouabat, Sveva Corrado, Faouziya Haissen, Geoffroy Mohn, and Dominique Frizon De Lamotte

Located in northern Morocco, the Rif belt represents the western edge of the Maghrebides system. This domain underwent a significant Cenozoic alpine compressional deformation, due to the collision between the North African margin and the south-western margin of the exotic Alboran Domain. This collision led to the development of a nappe stack during the Miocene.

This contribution aims to characterize the main tectonic mechanisms driving the evolution of the Rifain wedge, its burial-exhumation paths and to understand the former architecture of the North African paleo-margin. The work focuses mainly on the Flysch domain, originated from the Maghrebian branch of the Tethys and on the External domain (namely Intrarif, Mesorif and Prerif) that belong to the former north African margin. To define the thrust sheet stacking pattern and their burial-exhumation paths, a regional transect from Chefchaouen and Ouezzane towns (Central Rif), crossing the orogenic wedge from the Flysch to the Prerif Units is constructed.

The methodological approach consists in combining petrography and Raman micro-spectroscopy on organic matter and 1D thermal modelling, together with field structural data.

A new paleo-thermal data set of vitrinite reflectance (Ro%) and Raman micro-spectroscopy displays levels of thermal maturity between early and deep diagenetic conditions (Ro% ranges from 0.50% to 1.15%).

Preliminary results show an abrupt change in the thermal maturity and the rate of shortening in the Loukkos sub-unit (Intrarif Domain) that is structurally squeezed between Tangier sub-unit (Intrarif Domain) and the “Izzaren Duplex” (Mesorif).

Furthermore, previous studies show that the thickest crust below the Rif fold-and-thrust belt is located below the Izzaren area, suggesting a deep crustal imbrication at the transition between the Intrarif and the Mesorif. These observations joined with the thermal maturity data and 1D thermal modelling allow revisiting the structural evolution of the central part of the Rif belt, by defining the rate of shortening and proposing a new geological restoration with respect to the Mesozoic North African margin structural original setting.

How to cite: Schito, A., Atouabat, A., Corrado, S., Haissen, F., Mohn, G., and Frizon De Lamotte, D.: Structural styles of the External Rif and Flysch Domain (Rif belt, northern Morocco) through thermal maturity and structural data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19279, https://doi.org/10.5194/egusphere-egu2020-19279, 2020.

D1170 |
Rémi Leprêtre, Andrea Schito, Rachid Ouchaou, Mohamed El Houicha, and Francis Chopin

The Variscan belt in NW Africa is an intracontinental belt, resulting from far-field compressional stress during the closure of the Rheic Ocean between the Late Carboniferous and the Early Permian. In the classical view, this orogen building was preceded by a pre-orogenic stage, namely the Eo-variscan stage, suggested to have occurred at the Late Devonian-Early Carboniferous transition.

This view is now questioned, for multiple reasons. A first structural reason aims at re-interpreting the so-called Eovariscan features as extensional ones. Indeed, although many structures have been described, their integration into a compressional setting is not straightforward. A second reason is geodynamical, since this peculiar stage is bracketed between two general extensional phases recorded at the scale of NW Africa, and this leaves a very short time interval to proceed to a compressional phase that is geodynamically not integrated until today. At last, a third reason stems from early findings from metamorphic works in the Western Meseta that demonstrated the occurrences of previously unnoticed high geothermal gradients inside numerous Early Carboniferous basins (Chopin et al., 2014 ; Wernert et al., 2016 ; Delchini et al., 2018 ; Lahfid et al., 2019).

In this work, we sampled the Khenifra Basin within the easternmost part of the Western Meseta, where the Eovariscan deformation was defined (Allary et al., 1972). We carried on structural observations into the basement and sampled both the Ordovician basement and the Middle(?)-Late Visean series of the basin, which is thought the be extensional. Maximum temperatures reached by the 77 sampled rocks were obtained from the analysis of organic matter with the use of the Raman spectroscopy. The examination of this new dataset demonstrates that the Ordovician series acquired temperatures through a single event, consistently with their common record of the Eovariscan deformation. Instead, the unconformable Visean series on top of the basement show a pronounced basinal asymmetry, from low temperatures (< 160°C) to temperatures equivalent to the Ordovician ones (> 250°C). The Visean series do not record the Eovariscan deformation, and their thermal structure was acquired before the Variscan event, regarding their repartition within the basin. The examination of the different hypotheses for the timing of the maximal temperature acquisition (Variscan, compressional Eovariscan and extensional Eovariscan) leads to a single option only compatible with an extensional Eovariscan context.

The renewal on the knowledge about the early stages of the Variscan orogeny in NW Africa allows us to consider a Pyrenean-like model for the formation of this intraplate belt, resulting from the inversion of hot Early Carboniferous rifted basins.

How to cite: Leprêtre, R., Schito, A., Ouchaou, R., El Houicha, M., and Chopin, F.: A Pyrenean-like model for the Variscan belt in NW Africa : insights from thermometry-based Raman spectroscopy study in the Khenifra Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20672, https://doi.org/10.5194/egusphere-egu2020-20672, 2020.

D1171 |
Natalia Amanda Vergara, Marta Gasparrini, Sveva Corrado, and Stefano Bernasconi

A realistic reconstruction of the time-temperature history of sedimentary basins is critical to understand basin evolution and to predict oil maturation as well to assess reservoir quality. Carbonate rocks undergo diagenetic processes that modify their mineralogical and petrophysical properties. Understanding the temperature at which those processes occur and determining the geochemistry of the driving fluids is critical to constrain their occurrence and evolution in space and time.

Here, we put to the test the joint application of two independent techniques: the traditional fluid inclusion microthermometry (FIM) and the more recent clumped isotopes thermometer (∆47). We compare thermal information acquired by Δ47 thermometer and FIM on diagenetic carbonates having precipitated at temperatures between 60°C and 130°C in Upper Triassic reservoirs (depths of 1820-2450 m) from the well-known Paris Basin, and having suffered 120°C during maximum burial for about 20 Ma. A conventional diagenesis study (petrography, O-C isotope geochemistry) has been accomplished in samples from three different cores drilled in carbonate-cemented siliciclastic reservoir units of Norian age (Grés de Chaunoy Formation) and located in the northern part of the basin depocenter. A complete cement paragenesis was reconstructed highlighting three different burial cements: two non-ferroan blocky calcite phases (Cal1 and Cal2) and one non-ferroan dolomite phase of saddle type (Dol1). The progressively more negative δ18Ocarb suggests a possible increase in temperature, going from Cal1 to Dol1, whereas the consistently negative δ13C could indicate the involvement of continental fluids.

FIM indicates homogenization temperatures (Th) spanning from 60°C to 95°C (mode 67.5°C) for Cal1, 70°C to 110°C (mode 84°C) for Cal2, and 100°C to 130°C (mode 115°C) for Dol1. Δ47 measurements overall reveals lower temperatures for calcite cements, indicating probable thermal re-equilibration of the fluid inclusions, and a fairly similar temperature for the saddle dolomite cement. Uncertainties in the temperatures obtained through FIM and ∆47 thermometry and in the successively calculated δ18Ofluid, may lead to an erroneous assessment of the time of precipitation of the different diagenetic phases and to an erroneous thermal history and fluid-flow reconstruction. 

This work emphasizes the necessity of better understanding the limitations and applicability fields of these thermometric tools, especially when applied to burial diagenetic phases precipitated at temperatures above 100°C and/or in reservoirs having experienced temperatures in the gas window.

How to cite: Vergara, N. A., Gasparrini, M., Corrado, S., and Bernasconi, S.: Joint application of fluid inclusion and clumped isotope (Δ47) thermometry to burial carbonate cements from Upper Triassic reservoirs of the Paris Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20718, https://doi.org/10.5194/egusphere-egu2020-20718, 2020.

D1172 |
Rosanna Maniscalco, Sveva Corrado, Martina Balestra, Andrea Schito, Claudio Ivan Casciano, Martina Forzese, Sergio Montalbano, Alessandra Pellegrino, Andang Bachtiar, Giuseppe Palmeri, and Agata Di Stefano

The upper Triassic Streppenosa and Noto Formations are considered the main source rocks of the Hyblean Plateau in south-eastern Sicily, that represents the present-day deformed foreland of the Sicilian fold-and-thrust belt. This work focusses on the Upper Triassic Streppenosa and Noto Formations, penetrated by the Eureka 1 onshore well (south-eastern Sicily, Italy) in order to constrain the burial-thermal history of this basin of the western Tethys. According to previous paleogeographic reconstructions, starting from Norian, the palaeogeographic scenario consisted, moving from north to south, of a wide carbonate platform (Sciacca Fm.), adjacent to two different domains: the euxinic lagoon/basin of the Noto Formation, and, to the south, the basin of the Streppenosa Formation. Eureka 1 well is located in the inner portion of the platform-basin system and its Triassic succession consists of alternation of black shales and micritic, microbial dolomitic laminated limestones. A detailed description of the sedimentological facies from cores samples has been performed together with detailed organic petrography/Raman spectroscopy and clay mineralogy on fine grained sediments to assess thermal maturity of the Streppenosa and Noto Fms. The main facies consist of light-grey limestones (wackestone-mudstone) with scattered sub-angular intraclast, light grey finely laminated limestones, dark grey-black laminated mudstones, brownish undulated algal laminae saturated with bitumen. The cores are often bitumen saturated and interrupted by different sets of open microfractures, veins filled with calcite, and stylolites (parallel and vertical with respect to lamination) that may enhance and/or inhibit at places the fluid flow. Concerning thermal maturity, the studied interval falls in the lower-mid portion of the oil window, with robust agreement among the geothermometers derived from the three adopted techniques.

How to cite: Maniscalco, R., Corrado, S., Balestra, M., Schito, A., Casciano, C. I., Forzese, M., Montalbano, S., Pellegrino, A., Bachtiar, A., Palmeri, G., and Di Stefano, A.: Sedimentological features and thermal maturity signature of the upper Triassic Streppenosa and Noto Formations, source rocks in the Hyblean Plateau (SE Sicily, Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21703, https://doi.org/10.5194/egusphere-egu2020-21703, 2020.