# Syn- to post-rift thermal evolution of the Pechelbronn sub-basin (Upper Rhine Graben)

Laurie Tchang-Tchong, Raymond Michels, Laurent Beccaletto

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Laurie Tchang-Tchong, Raymond Michels, Laurent Beccaletto. Syn- to post-rift thermal evolution of the Pechelbronn sub-basin (Upper Rhine Graben). Geothermics, 2025, 129, pp.103296. 10.1016/j.geothermics.2025.103296. hal-05003718

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# Syn- to post-rift thermal evolution of the Pechelbronn sub-basin (Upper Rhine Graben)

Tchang-Tchong Laurie<sup>a,b,*</sup> ◐, Michels Raymond<sup>a</sup>, Beccaletto Laurent<sup>c</sup>

## ARTICLE INFO

**Keywords:**

Miocene erosion

Paleo-burial

Heat flow evolution

2D basin thermal modelling

Upper Rhine Graben

## ABSTRACT

The Upper Rhine Graben (URG) is a key target for geothermal projects in Western Europe, requiring an understanding of the development and spatial evolution of geothermal fluids. Its thermal and geological history was impacted during the Neogene period by a major change in rift kinematics, evidenced by a regional-scale and gradual erosive unconformity and coeval volcanic activity. This study investigates the interplay between URG syn- and post-rift burial history and heat flow evolution in the westerly Pechelbronn sub-basin - hosting petroleum and geothermal fields – in comparison to the more central Rastatt Trough. The method uses thermal maturity assessment by vitrinite reflectance and 2D burial coupled to conductive thermal modelling. Results reveal that the maximum burial occurs during the Aquitanian (post-rift), and that the maximum cumulative sediment thickness related to the Neogene erosion was approximately 1200 m in the Pechelbronn sub-basin, from the top of the Schistes à Poissons (Rupelian shale) to the Aquitanian sediments. Toarcian source rock (Schistes carton) reached the oil window at 29–28 Ma within the Pechelbronn sub-basin and at 43 Ma for the Rastatt Trough at Roeschwoog well. The comparison of current adjacent local heat anomalies reveals variations in thermal history of the Pechelbronn sub-basin, highlighting the dominant influence of syn-rift burial in some areas, e.g. in Soultz-sous-Forêts or additional heat input attributed to geothermal fluids in others, e.g. in Rittershoffen. Moreover, it appears that the heat flow must have been considerably higher (around 180 mW/m², under the pure conduction hypothesis) during faults activation around 15 Ma in the Rittershoffen area, compared to Soultz-sous-Forêts (150 mW/m²). Changes in local heat flows are attributed to east-west migration of hydrothermal cells positions through time in relationship to fluid circulation at basin scale. These results provide a broad geological time frame for further thermal modeling in the URG and provide new insights into the thermal evolution of the URG and its implications for sub-surface resources exploration.

## 1. Introduction

The Upper Rhine Graben (URG) is one of the key targets for geothermal projects in Western Europe (Frey et al., 2022) and by extension, for the co-exploitation of lithium-bearing geothermal brines (Fries et al., 2022; Sanjuan et al., 2022). As a result, it is important to understand when geothermal fluids developed and how they have evolved spatially and in thermal intensity. Recent studies have focused on the burial history of the URG (Böcker et al., 2016; Tchang-Tchong, 2023). Yet, the thermal and geological history reconstruction remains affected by the difficult-to-characterize Neogene period, corresponding to a major change in rift kinematics (Villemin et Bergerat, 1987;

Schumacher, 2002), attributed to the transition from rifting dynamics to lithospheric folding during Burdigalian (Bourgeois et al., 2007). This resulted in a gradual erosional unconformity from the north to the south of the graben, coeval to the uplift resumption of the Vosges and the Black Forest Arch (Roll, 1979; Dezes et al., 2004; Rotstein and Schaming, 2008). This period was accompanied by regional volcanism, e.g. the volcanic domes of the Kaiserstuhl to the south of the URG (Schumacher, 2002) and the Vogelsberg to the north (Bogaard and Wörner, 2003). It was later over imposed by uneven erosions following the late and highly partitioning of the graben (Roll 1979; Brun et al., 1992; Derer et al., 2005; Haimberger et al., 2005; Beccaletto et al., 2010; Rotstein and Schaming, 2011). Although the timings of faults activation or

<footnote><sup>a</sup> Université de Lorraine, CNRS, GeoRessources, UMR 7359, France</footnote>

<footnote><sup>b</sup> Université de Lorraine, CNRS, LIEC, UMR 7360, France</footnote>

<footnote><sup>c</sup> BRGM, Orléans F-45060, France</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: laurie.tchang-tchong@univ-lorraine.fr (T.-T. Laurie).</footnote>
reactivation during the syn- and post-rift are still poorly described in the area, it would appear that most of faults are likely to have developed around 15 Ma (Person and Garven, 1992). This raises major challenges for geothermal reconstruction as Neogene faulting could be responsible for the initiation of the hydrothermal convective cells (Lemgruber-Traby et al., 2023), partly responsible for the URG's present-day high surface heat flows (Kohl and Mégel, 2007; Guillou-Frottier et al., 2013; Vallier et al., 2018). This study focuses on the Pechelbronn sub-basin (western part of the central URG segment) hosting the Soultz-sous-Forêts and Rittershoffen geothermal fields, while also comparing data with the deeply buried eastern part, i.e. the Rastatt Trough (GeORG project team, 2013).

The main challenges to the thermal evolution of the central URG is to estimate the average Tertiary thickness of eroded sediments. As organic matter is a sensitive marker used in many basin studies as an excellent witness of thermal evolution through time (Barker, 1981; Tissot et al., 1987; Robert, 1988; Barker, 1989; Naeser and McCulloh, 1989), the aim of the paper is to couple organic thermal maturity markers with 2D thermal basin modelling (PetroMod© software) in order to discern the respective contributions of the burial and the external heat input (heat flow) to the thermal history. The work proposes conductive thermal

basin modelling based on: 1) the pre-selection of target areas mainly based on the presence of geothermal anomalies and on the thickness of preserved syn- to post-rift sediments; 2) the syn- to post-rift tectono- sedimentary and thermal history of the URG; 3) the observation and interpretation of seismic profiles to characterize the main periods of faults activity in the Pechelbronn sub-basin; 4) the assessment of the organic thermal maturity recorded along pre-selected well profiles; 5) the modelling of four synthetic geological cross-sections (including de- posits from Permian to the present-day) and their thermal calibrations by adjusting the heat flows over time.

Once the conductive model is constrained, any deviation between the modelled evolution of the organic matter maturity and that observed in wells can be attributed to convective geothermal system. This study explores how a distinctive geothermal system develops over time within an intracontinental sedimentary basin, where unusually elevated thermal gradients have been recorded. The geological scenario provided should bring new insights to the understanding and the evaluation of the lifespan and spatio-temporal dynamic concepts in regard to the convective geothermal system.

<figure><img src="image_4.png" /><figcaption>**Fig. 1.** Location of studied area. a. Simplified map of the borders between France (FR), Germany (DE), Switzerland (CH) with the URG limits and location of the Pechelbronn sub-basin. b. Simplified geological map of the URG surroundings with limits of the study area and the Pechelbronn sub-basin based on Equipe du projet GeORG (2013) and the geological map of France 1/1 000 000, BRGM (Chantraine et al., 1996).</figcaption></figure>
## 2. Geological background

### 2.1. General geological features of the URG

The URG is a major segment of the European Cenozoic Rift System (ECRIS, Dèzes et al., 2004) (Fig. 1). It trends NNE/SSW and extends partly in France, Germany and Switzerland over 300 km from the Rhenish Massif to the north (Ziegler, 1992) to the Jura Mountains to the south. To the west, it is limited by the Western Main Border Fault, separating the URG from the Vosges Mountains, the eastern Paris Basin and the Saverne Fracture Field. To the east it is limited by the Eastern Main Border Fault, separating the URG from the corresponding units of the Black Forest, the Odenwald and the Franconian Platform (Fig. 1). Its opening and development were controlled by the Pyrenean and Alpine orogens dynamics (Schumacher, 2002; Dèzes et al., 2004), resulting in a polyphase tectonic rift evolution and related syn- to post-rift sedimentation (Laubscher, 1987; Sissingh, 1998, 2006; Schumacher, 2002).

### 2.2. Present-day geothermal features of the study area

Positive local thermal anomalies exist in the URG, mainly along its western edge, for example in France in Soultz-sous-Forèts, Rittershoffen, Scheibenhard (Fig. 2), and in Germany in Landau and Insheim. These anomalies are characterized by temperatures exceeding 150 °C at 2000 m below the surface (Schellschmidt and Clauser, 1996; Baillieux et al., 2013; GeORG project team, 2013; Fig. 2). Traditionally, high heat flows in rift basins are associated with the stretching and thinning of the lithosphere (McKenzie, 1978). However, the thinning of the lithosphere in the URG has long been considered insufficient to explain the current measured thermal anomalies (Edel et al., 1975; Zucca, 1984). Since then, it has been demonstrated that the high and local geothermal gradients observed in the URG (Laurent, 1974) are correlated with the 1) lithological nature of the crystalline basement, 2) its structural inheritance (Edel, 2007), 3) groundwater circulations at the basin scale (Schellschmidt and Clauser, 1996; Pribnow and Schellschmidt, 2000; Guillou-Frottier et al., 2013) and 4) hydrothermal convective cells in the fractured crystalline basement and at the sediment-basement interface (Clauser and Villinger, 1990). These are controlled by the overall

<figure><img src="image_5.png" /><figcaption>**Fig. 2.** Simplified structural map of the study area (red frame; see Fig. 1) depicting the thickness of tertiary sediments in shades of gray and the outlines of the 150 °C isotherm at approximately 1700 m depth (red), approximately 2300 m depth (orange), and approximately 2900 m depth (yellow) (based on Equipe du projet GeORG, 2013). Abbreviation: Soultz: Soultz-sous-Forèts.</figcaption></figure>
geometry of the basin and fault systems.

## 2.3. Pre-rift tectono-sedimentary history of the URG

Following the demise of the Variscan orogen, continental clastics deposits filled vast fault-controlled basins from the Uppermost Carboniferous to the Lower Permian, like the Lorraine-Saar-Nahe basin north of the URG (Boigk and Schöneich, 1970; Donsimoni, 1981; Hemelsdaël et al., 2023) (Fig. 1). From the Late Permian until at least the mid-Jurassic, the future URG area underwent post-organic thermal subsidence (Cloething and Ziegler, 2007), leading to the deposition of the complete Triassic sequence and the Jurassic units (Supplementary data), at present partly eroded (Malm and Cretaceous units are completely absent). The Liassic deposits contain the major source rocks of the URG, i.e. Hettangian/Sinemurian and Toarcian (Supplementary data), also extending over the entire Central Europe Basin System (Littke

et al., 2008). These formations are overlain by Dogger carbonates until the Callovian (Aichholzer, 2016). The lack of Upper Jurassic and Cretaceous deposits is attributed to the uplift-erosion phase from the Cretaceous to Paleocene (Ziegler, 1987). This slight compressional phase led to moderate folding and southward tilting of the Mesozoic series in the whole area, triggering their erosion before syn-rift sedimentation (Sittler, 1967; Ziegler, 1990; Lutz and Cleintuar, 1999; Bourgeois et al., 2007; Grimmer et al., 2017).

## 2.4. Syn- to post-rift tectono-sedimentary history of the URG

The first Cenozoic sediments correspond to siderolitic formations and residual clays resulting from weathering of the Mesozoic carbonates (Sittler, 1965; Duringer, 1988; Schumacher, 2002; Duringer et al., 2019). They are locally associated with lignite-rich Lutetian lacustrine sediments (Formation de Bouxwiller in Fig. 3; Sittler, 1965; Ménillet

<figure><img src="image_6.png" /><figcaption>**Fig. 3.** Longitudinal section through the URG from north to south, illustrating variations in thickness and lithofacies of tertiary formations over time and position within the basin. Adapted from Hinsken et al. (2011) and based on Von Eller and Sittler (1974). The base and top of the Schistes à Poissons (Rupelian shales) are shown in dotted red in the lithostratigraphy column. Abbreviations: Gp.: Group; Up. : Upper ; Low. : Lower ; Sup.: Supérieures (Upper); Moy.: Moyennes (Middle); Inf.: Inférieures (Lower). The stratigraphic formations comprising sets 1, 2, 3, 4 are described by Grimm et al. (2011).</figcaption></figure>
et al., 2015). This slight Eocene resumption of subsidence marks the early rifting phase, also evidenced by volcanic activity (Schumacher, 2002; Lutz et al., 2013; Ménillet et al., 2015), and by the deposition of marly clays and calcareous formations of Bartonian age (Châteauneuf and Ménillet, 2014; Duringer et al., 2019).

### 2.4.1. Overview of the syn-rift period

The onset of the syn-rift phase was initiated in the Priabonian (Eocene; Duringer, 1988; Berger et al., 2005; Derer et al., 2005; Ménillet et al., 2015). The initiation phase is mainly marked by the development of topographic reliefs, reflected in the sedimentation by the coarse fluvial conglomerates deposited along the URG margins (Duringer, 1988). The increase in syn-rift tectonic subsidence is recorded in the Pechelbronn sub-basin by the deposition of the Dolomitic Group, followed by the Couches de Pechelbronn Inférieures (Fig. 3). Following this, the Eocene-Oligocene transition (i.e. Priabonian-Rupelian) is marked in the sedimentary record by the deposition of the Couches de Pechelbronn Moyennes (Fig. 3). This formation corresponds to the first Rupelian marine transgression. This is followed by the deposition of the Couches de Pechelbronn Moyennes and the Couches de Pechelbronn Supérieures (Fig. 3), mainly made of siliciclastic and evaporitic rocks, which specifically contain the main traps of the Pechelbronn oil fields (Wannesson, 1998).

The syn-rift ended upon the widespread Late Rupelian marine transgression known throughout the entire URG and starting point of the post-rift phases (deposition of the Série Grise; Fig. 3) (Schumacher, 2002; Berger et al., 2005; Roussé, 2006; Le Metayer, 2007). This episode is mainly highlighted by the deposition of the Schistes à Poissons (Fig. 3), corresponding to one of the main URG petroleum source rocks (Bruss, 2000; Böcker et al., 2017; Tchang-Tchong, 2023).

### 2.4.2. Overview of the post-rift 1 period

By the end of the Oligocene, the central segment of the URG was reactivated as a pull-apart basin (Schumacher, 2002), specifically in the Rastatt area, and characterized by the deposition of the Couches de Niederroedern (Fig. 3). In the Aquitanian (basal Miocene), the main depocenter migrated northwards marking the Aquitanian marine transgression recorded by the deposition of the Worms-subgroup (Fig. 3), while its central and southern segments were uplifted (Schumacher, 2002; Rotstein and Schaming, 2008). The uplifted zone extended from the Jura thrusts in the south to the Kaiserstuhl and is probably associated with the doming of the external part of the Alpine foreland (Sinclair et al., 1991). The Aquitanian marine transgression was then interrupted at the end of the Langhian, due to the progressive thermal doming of the Rhenish Massif (Fuchs et al., 1983). This event marks the end of a first post-rift episode, described in this study as post-rift 1 (Fig. 3). The previously deposited Oligocene and Miocene series were then eroded from the N/NW to the S/SE (Roll, 1979) in relation to the uplift resumption of the Vosges and Black Forest crystalline massifs (Roll, 1979; Rotstein and Schaming, 2008) and associated with volcanism (Fig. 3; Schumacher, 2002; Bogaard and Wörner, 2003; Dèzes et al., 2004).

### 2.4.3. Overview of the post-rift 2 period

Following the post-rift 1 period, a widespread non-depositional period extended from the end of the Serravallian to the Pliocene (Perner, 2018) (Fig. 3) inducing a dissimilarly evolution between northern, central and southern URG segments (Perner, 2018). Especially, the eastern part of the URG central segment (the Rastatt Trough) had much higher sedimentation rates than its western central part (the Pechelbronn sub-basin). Finally, the end of the post-rift period deposits results from rapid, major geodynamic changes in the Plio-Quaternary, and are overlaid by most recent sediments of glacial events (Ellwanger et al., 2005). This episode witnesses the end of post-rift 2 (Fig. 3).

## 3. Acquisition of organic geochemistry data for the calibration of 2D models

### 3.1. Sampling and measured data

A set of cores and drill cuttings was collected from the geothermal wells GPK-1, GRT-1 of the Pechelbronn sub-basin, as well as from oil wells SCB F102, SCB-101 and RO1 of the western part of the Rastatt Trough (Fig. 2). The organic petrography analyses were conducted by the Egs-ploration Organic Petrology Laboratory (Rueterswil, Switzerland). The analysis methods employed follow the guidelines published by the International Organization for Standardization (ISO 7404-2, ISO 7404-3, and ISO 7404-5). All measurements are shown in Table 1. Rock-Eval analysis was performed at ISTO laboratory, Orléans, France (Le Meur et al., 2021).

### 3.2. Calibration principles

2D thermal conduction modelling was carried out using the Schlumberger PetroMod© software (Hantschel and Kauerauf, 2009). The concepts of numerical and thermal maturity modelling were previously published by Waples et al. (1992a, 1992b), Poelchau et al. (1997), and Yalcin et al. (1997). For all modelling in this study, organic thermal maturity markers were used to calibrate the thermal history. Heat flows input data were adjusted to fit the measured maturity markers values.

## 4. Methodology and thermal modelling procedures

### 4.1. Selecting areas for modelling

The Soultz-sous-Forëts (GPK-1 well), Rittershoffen (GRT-1 well), Scheibenhard (SCB-101 and SCB F102 wells) and Roeschwoog (RO1 well) sections were selected according to 1) the availability of samples (%Ro measurements), 2) the structural configuration of the area and the associated preserved post-rift sediments thickness and 3) the presence or not of a present-day positive thermal anomaly (Fig. 2). Their respective parameters are provided in Table 2.

### 4.2. Setting up 2D sections for modelling

Synthetic geological sections were constructed from the GeORG 3D model (Équipe du projet GeORG, 2013), and validated by the observation and interpretation of seismic profiles provided by BRGM (Beccalletto et al., 2010). These west-east synthetic geological sections illustrate the main structural system and simplified limits of major lithostratigraphic units. Only the first-order geological parameters are represented, e.g. major faults (Fig. 4).

### 4.3. Overview of the main input data for modelling

The initial inputs correspond to the major lithostratigraphic units that are deduced from the URG 3D model (Equipe du projet GeORG, 2013). Their absolute ages were defined from the chronostratigraphic chart proposed by Cohen et al. (2013, 2019) (Supplementary data). The Liassic origin of the Pechelbronn oils (Ploethner, 1988; Blümel et al., 1989; Richard, 1994; Bruss, 2000; Böcker et al., 2017; Tchang-Tchong, 2023) and the availability of kinetic data from the literature led to choose the Toarcian and the Rupelian source rocks as references in modelling (Supplementary data). These source rocks were modelled using the type II kerogen kinetic model of Behar et al. (1997). Formation thicknesses were derived from the drilling logs of the selected calibration wells and considered as isopach for all synthetic geological sections derived from seismic profiles interpretation. The lithological mixes of the lithostratigraphic units were deduced from the geological data synthesized by the GeORG project (Equipe du projet GeORG, 2013) and
<caption>**Table 1**</caption>

Rock-Eval Total Organic Carbon (TOC%) Rock-Eval and vitrinite reflectance (%Ro) from cores and cuttings samples of the calibration wells GPK-1, GRT-1 and RO1.

<table><thead><tr><th>Well code</th><th>Locality</th><th>Sample type</th><th>Depth (m)</th><th>Stratigraphic formation</th><th>Stage/Age</th><th>TOC (%)</th><th>% Ro</th><th>Std. Dev.</th><th>Cnt</th><th>Conf. (95 %)</th></tr></thead><tbody><tr><td rowspan="4">GPK-1</td><td rowspan="4">Soultz-sous-Forêts</td><td rowspan="4">Cuttings</td><td>625</td><td>Schistes carton</td><td>Toarcian</td><td>6.45</td><td>0.75</td><td>0.04</td><td>13</td><td>0.03</td></tr><tr><td>630</td><td>Calcaire de Kirrwiller - Marnes à Septaria</td><td>Pliensbachian</td><td>3.18</td><td>0.74</td><td>0.08</td><td>20</td><td>0.04</td></tr><tr><td>640</td><td>Marnes à ovoïdes</td><td rowspan="2">Hettangian/ Sinemurian</td><td>1.32</td><td>0.81</td><td>0.06</td><td>18</td><td>0.03</td></tr><tr><td>735</td><td>Marnes et calcaires à Gryphées</td><td>1.17</td><td>0.82</td><td>0.04</td><td>13</td><td>0.02</td></tr><tr><td rowspan="5">GRT-1</td><td rowspan="5">Rittershoffen</td><td rowspan="5">Drill cores</td><td>435</td><td>Schistes à Poissons</td><td>Rupelian</td><td>2.51</td><td>0.76</td><td>0.06</td><td>12</td><td>0.04</td></tr><tr><td>1315</td><td>Couches à Dactylioceras</td><td>Toarcian</td><td>2.71</td><td>1.53</td><td>0.05</td><td>7</td><td>0.05</td></tr><tr><td>1321</td><td>Schistes carton</td><td rowspan="2">Pliensbachian</td><td>3.71</td><td>1.65</td><td>0.06</td><td>16</td><td>0.03</td></tr><tr><td>1327</td><td>Marnes à Septaria</td><td>2.23</td><td>1.90</td><td>0.06</td><td>14</td><td>0.04</td></tr><tr><td>1430.5</td><td>Marnes et calcaires à Gryphées</td><td>Hettangian/ Sinemurian</td><td>1.2</td><td>2.35</td><td>0.07</td><td>12</td><td>0.04</td></tr><tr><td rowspan="3">SCB F102</td><td rowspan="3">Scheibenhard</td><td rowspan="3">Drill cores</td><td>1655.9</td><td>Marnes et grès de Schalkendorf</td><td>Aalenian</td><td>1.64</td><td>0.82</td><td>0.06</td><td>16</td><td>0.03</td></tr><tr><td>1768</td><td>Argiles d'Obermodern</td><td>Sinemurian</td><td>1.52</td><td>1.71</td><td>0.08</td><td>10</td><td>0.06</td></tr><tr><td>1770</td><td>Marnes et calcaires à Gryphées</td><td>Hettangian/ Sinemurian</td><td>1.71</td><td>0.57</td><td>0.06</td><td>15</td><td>0.03</td></tr><tr><td>SCB-101</td><td rowspan="3">Roeschwoog</td><td rowspan="3">Drill cores</td><td>1610.5</td><td>Marnes de Gundershoffen</td><td>Aalenian</td><td>1.22</td><td>0.93</td><td>0.05</td><td>8</td><td>0.04</td></tr><tr><td>1430.5</td><td>Couches de Pechelbronn Supérieures</td><td>Rupelian</td><td>1.66</td><td>0.66</td><td>0.05</td><td>20</td><td>0.02</td></tr><tr><td></td><td>1958.5</td><td>Fm. d'Etendorf</td><td></td><td>0.94</td><td>1.35</td><td>0.07</td><td>12</td><td>0.05</td></tr><tr><td>RO1/ 4719</td><td></td><td></td><td></td><td>2107.2</td><td>Marnes de Printzheim</td><td></td><td>1</td><td>1.63</td><td>0.08</td><td>13</td><td>0.05</td></tr><tr><td></td><td></td><td></td><td></td><td>2277.7</td><td>Marnes et Calcaires à Gryphées</td><td></td><td>6.78</td><td>1.69</td><td>0.08</td><td>20</td><td>0.04</td></tr></tbody></table>

Abbreviations: Std. Dev.: Standard Deviation; Cnt: Count; Conf.: Confidence; Fm.: formation.

<caption>**Table 2**</caption>

Overview of targeted parameters recorded in the Pechelbronn area at Soultz-sous-Forêts, Rittershoffen, Scheibenhard and Roeschwoog. Temperatures (°C) at depth (m) are from the 3D GeORG model (Equipe du projet GeORG, 2013).

<table><thead><tr><th>Well Code</th><th>Location</th><th>Source rocks structural position</th><th>Post-rift crossed by calibration wells</th><th>Temperatures (°C) at depth (m)</th></tr></thead><tbody><tr><td>GPK-1</td><td>Kutzenhausen/ Soultz-sous-Forêts</td><td>Liassic SR in the hanging wall</td><td>Absence</td><td>135–160 °C at 1500 m below surface</td></tr><tr><td>GRT-1</td><td>Rittershoffen</td><td>Liassic SR in the hanging wall</td><td>≈ 400 m of Série Grise</td><td>105–135 °C at 1500 m below surface</td></tr><tr><td>SCB F102 SCB-101</td><td>Scheibenhard</td><td>Liassic SR in the footwall</td><td>368 m of Couches de Niederroedern 454 m Série Grise</td><td>105–120 °C at 1500 m below surface</td></tr><tr><td>RO1/ 4719</td><td>Auenheim/ Roeschwoog</td><td>Liassic SR in the footwall</td><td>883 m of Couches de Niederroedern 464 m of Série Grise</td><td>75–90 °C at 1500 m below surface</td></tr></tbody></table>

Abbreviations: SR: source rocks; Fm.: Formation.

from the Haguenau geological map note for the source rocks (Ménillet et al., 2015).

### 4.4. Outlines of the thermal modelling and initial boundary conditions

Principles of the heat flow model used in this paper are described in Hantschel and Kauerauf (2009). In the lithosphere the heat flow is mainly caused by the temperature difference between the asthenosphere-lithosphere limit and the sediment-water-interface which both define the boundary conditions of the model. Modelling was performed as steady state and transient effect are applied when thermal boundary conditions, geometry, properties or temperatures are modified through time by subsidence (sedimentary deposition) or uplift (erosion). Thermal conductivities (based on Sekiguchi model), specific heat

capacities and radiogenic heat production of each geological unit are taken into account (supplementary data). Pore fluid functions are applied in regards to water content. Since compaction and overpressure driven water velocities are small, compaction driven convection is neglected in the thermal budget. Convection has not been modelled in this paper. Heat flow calibration was performed by comparing kerogen thermal maturation modelling to maturity profiles measured in wells. Any significant deviation between modelled and measured thermal maturity is attributed to change in heat flow. Additional heat input may then be assumed as related to convection, since this actually occurs in the present-day fractured substratum of the URG.

For all the models, the Paleo-Water Depth (PWD) was estimated according to facies type, from 0 m for continental deposits to 100 m for deep marine environment deposits (Röhl et al., 2001; Blaise, 2012). Throughout the Cretaceous to Paleocene period, PWD is considered to be equal to 0 m. If sediments were deposited, they mainly referred to continental paleoenvironments (Tchang-Tchong et al., 2023). The Sediment-Water Interface Temperature (SWIT) is derived from the compilation proposed by Bruss (2000), based on palynological and palynofacies studies defined by Stahmer (1980), Schuler (1990), Sittler and Ollivier-Pierre (1994). The evolutions of the estimated PWD and SWIT over time are given in the Supplementary data.

The evolution of heat flow over time is from Bossennec et al. (2021) and is given in the Supplementary data. The hydrothermal episode dated around 150 Ma (Blaise et al., 2016) was not considered as a thermal peak in Bossennec et al. (2021) but is nevertheless in the same range as the thermal peak identified by these last authors at around 180 Ma. Present-day heat flows considered are (Table 2): 150 mW/m² in Soultz-sous-Forêts (Kohl and Mégel, 2007), 130 mW/m² in Rittershoffen (Vallier et al., 2018), same value used for the Scheibenhard area, which displays a similar thermal anomaly (Guillou-Frottier et al., 2013) (Table 2). In Roeschwoog, there is no thermal anomaly (82 mW/m², Bossennec et al., 2021).

### 4.5. Initial assumptions

#### 4.5.1. Determining the timing of fault activation and reactivation

The geometries of the deposits and their relationship to the faults were observed on seismic profiles of the Pechelbronn sub-basin. The main periods of major faults activity were determined and qualified as
<figure><img src="image_7.png" /><figcaption>**Fig. 4.** Synthetic W-E geological sections (scale 1:1) based on the GeORG 3D model (Equipe du projet GeORG, 2013) and observation of seismic profiles of the Pechelbronn area (Beccaletto et al., 2010), with the horizons of the lithostratigraphic sets defined. a. Soultz-sous-Forêts with the position of well GPK-1 (total depth of well not shown on section). b. Rittershoffen with the position of well GRT-1. c. Roeschwoog with the position of well RO1(4749) at depth. d. Scheibenhard with the position of well SCB-101. Abbreviations: b.: Base; Musch.: Muschelkalk; Bunt.: Buntsandstein. Fault identification: numbered 1 to 3, from west to east.</figcaption></figure>

syn-rift or post-rift (Fig. 5). Throughout the URG, the Couches de Pechelbronn are associated with the syn-rift period (around 37–32 Ma) and are overlaid and sealed by the Série Grise, corresponding to the start of post-rift phase (Fig. 3). A fault is identified as syn-rift when the Couches de Pechelbronn show fan-type depositional geometries or at least thickness variations of syn-rift deposits on both sides; while post-rift activity is identified where the faults intersect the post-rift units (Série Grise and Worms-subgroup around 16–15 Ma) (Fig. 3). In this study, post-rift 1 includes the Série Grise, the Couches de Niederroedern, the Couches à Cérithes and the Couches à Hydrobies, from 32 to 15 Ma (“Worms-subgroup” of Chattian-Aquitanian age; Fig. 3). Post-rift 2 comprises the long-lasting non-deposition period and its tectono-sedimentary history during the Plio-Quaternary, between 15 and 0 Ma (Fig. 3).

Observations from seismic profiles were transposed to synthetic geological cross-sections to assign periods of activity to the major faults (numbered 1 to 3, from west to east; Fig. 4). It appears that in the Pechelbronn sub-basin, almost all the faults were activated/reactivated during post-rift period (considered around 15 Ma), except for the fault junction at Soultz-sous-Forêts (syn- and post-rift; Fig. 5). Faults in the Soultz-sous-Forêts section were active during syn-rift (37–32 Ma) and post-rift (15–0 Ma). In contrast, the flower structure in the Rittershoffen section was active during the post-rift phase only (15–0 Ma; Fig. 5). Faults west to the Scheibenhard section (Fig. 4) were only active during post-rift (15–0 Ma, Fig. 5), unlike the easternmost one (Fig. 4), which

was also active during syn-rift period (37–32 Ma; Fig. 5). Concerning the Roeschwoog geological section, the unique fault was active during syn-rift (37–32 Ma) and post-rift periods (15–0 Ma) (Fig. 5).

### 4.5.2. Calibration and modelling of pre-rift paleo-thicknesses

The reconstruction of the pre-rift burial and thermal history (from Permian to Paleocene) is described in Tchang-Tchong et al. (2023). The authors demonstrate that the period of major Cretaceous/Paleocene hiatus can be modelled by considering the following scenario: deposition of 160 m of Middle Jurassic, followed by the deposition of 300 m of Upper Jurassic from 160 to 145.1 Ma, and then by a hiatus period from 140 to 70 Ma, completed by the total erosion of the Upper Jurassic and the partial erosion of the Middle Jurassic, from 60 to 50 Ma. This scenario is used in the 2D thermal models. The eroded stratigraphic formations from the Cretaceous/Paleocene could not be modeled as separate units. Instead, the thickness of the top preserved formation (Aalenian) is combined with an estimated 460 m of eroded sediment, added to the model at 171 Ma (Tchang-Tchong et al., 2023; Supplementary data).

### 4.5.3. Assessment of post-rift paleo-thicknesses

In the Pechelbronn sub-basin specifically, the preserved Tertiary deposit thicknesses are particularly heterogeneous (Fig. 2). For example, the Soultz-sous-Forêts and Rittershoffen sections reveal smallest post-rift sediment thicknesses, in contrast to the Scheibenhard and Roeschwoog
<figure><img src="image_8.png" /><figcaption>**Fig. 5.** Detailed structural map of the study area produced from BRGM data. a. The Gray area framed in black dotted lines corresponds to the area studied from seismic profiles (Beccaleto et al., 2010). b. Zoom on the area studied: blue circles correspond to the intersection of a seismic profile with a post-rift fault (post-Série Grise), red circles circled in blue correspond to the intersection with a syn- and post-rift fault and blue circles to the intersection with a fault that played at least at post-rift (uncertainty for syn-rift).</figcaption></figure>

sections (Fig. 4), located in the west/south-west extension of the Rastatt Trough. However, the thickness of the Série Grise (start of post-rift) may be considered as isopach throughout the URG, while the Worms-subgroup thickness (post-rift 1) can be considered uniform across the Pechelbronn sub-basin. The thickness of this subgroup is currently very heterogeneous (Section 2.4). This heterogeneity is overall the consequence of the tilting, gradual erosion of previously deposited series during Mid-to-late Miocene (post-rift 1) and the activation/reactivation of faults at around 15 Ma followed by subsequent erosion of the geological formations (post-rift 2; Fig. 3). For these reasons, the estimation of paleo-thicknesses of Miocene-eroded sediments in the Pechelbronn sub-basin cannot be based on a representative URG-wide approach but must be estimated locally.

The Roeschwoog geological section includes the structural limit of the eastern Pechelbronn sub-basin with the Rastatt Trough (Fig. 4). The thickness of post-rift sediments currently preserved to the east of the Roeschwoog section (Rastatt Trough) is about 1200 m above the Schistes à Poissons. By analogy, it is considered as the potential average thickness of sediments of same age that could have been deposited within the Pechelbronn sub-basin before erosion. This assumption has been adopted for the conductive thermal modelling of the synthetic sections of Soultz-sous-Forêts and Rittershoffen. The estimated amounts of post-rift Chattian-Aquitanian sediments to be added to the current thicknesses vary according to the section studied:

- At Roeschwoog: uniform post-rift thickness of around 1200 m above the Schistes à Poissons;

- At Scheibenhard: uniformization of post-rift over a thickness of around 1350 m;

- At Soultz-sous-Forêts: uniformization of the post-rift preserved to the east of the section (base of the Série Grise), followed by additional post-rift of ≥ 700 m;

- At Rittershoffen: uniformization of the preserved post-rift (Série Grise) then post-rift supplement of ≥ 500 m.

The estimated paleo-thicknesses of post-rift sediments were implemented to the models at 28 Ma. The adjustment of paleo-thicknesses is then relayed by a period of sedimentary hiatus from 28 to 16 Ma, followed by a period of erosion at 16–15 Ma (Supplementary data).

## 5. 2D models calibration based on vitrinite reflectance (%Ro)

The pre-rift history is based on the conclusions established in Tchang-Tchong et al. (2023), indicating that source rocks are immature before the onset of the URG while 460 m of Upper Jurassic/Cretaceous sediments are considered to have been eroded during Paleocene. Vitrinite reflectance (%Ro) is used to calibrate the 2D thermal models, using the "Easy%Ro" kinetic model proposed by Burnham (2019). Comparisons of measured %Ro with simulated values as a function of depth are presented in Figs. 6, 7 and 8.

### 5.1. Calibration of the Soultz-sous-Forêts conductive thermal model

The %Ro values measured in well GPK-1 (Soultz-sous-Forêts) within the Mesozoic range from 0.6 %Ro to 1 %Ro (Table 1 and Fig. 6). The simulated %Ro matches with the measured values. These results suggest that the 2D thermal model scenario for Soultz-sous-Forêts, based on the initial boundary conditions and pre-established assumptions, is acceptable.
<figure><img src="image_9.png" /><figcaption>**Fig. 6.** Evolution of %Ro measured in the GPK-1 well (black crosses; Soultz-sous-Forêts area) and simulated (red curve; Burnham, 2019) as a function of depth, focused on the measurements and the range 0.10–4.00 %Ro (logarithmic scale), with the 0.60 %Ro isoline in light gray representing the onset of the oil window (PetroMod®). Error bars: 95 % confidence interval.</figcaption></figure>

## 5.2. Calibration of the Rittershoffen conductive thermal model

In well GRT-1 (Rittershoffen), measured %Ro values are much higher (Table 1 and Fig. 7a). This means that the modelling scenario used for Soultz-sous-Forêts leads clearly to an underevaluation of the thermal maturity level, indicating that the chosen boundary conditions (burial and/or heat flow) are not valid for the Rittershoffen section. However, the burial histories of Rittershoffen and Soultz-sous-Forêts areas during the Chattian-Aquitanian are similar, given their close positions in the sub-basin (≈ 6.5 km distance), both exhibit similar petrography of the top crystalline basement (Baillieux et al., 2014), so the thermal basin modelling differences can only be attributed to a different heat flow history. For this reason, heat flow evolution was revised for the Rittershoffen model.

The additional simulation tests conducted were based on the adjustment of the heat flow only from 16 to 0 Ma. The various scenarios tested are described below, and the modelling results can be found in Fig. 7b:

- **Black curve:** simulated %Ro obtained for a heat flow of 87.5 mW/m² at 16 Ma, 160 mW/m² at 15 Ma and 160 mW/m² at 0 Ma and 120 mW/m² at 16 Ma, 160 mW/m² at 15 Ma and 160 mW/m² at 0 Ma;

- **Purple curve:** simulated %Ro obtained for a heat flow of 90 mW/m² at 16 Ma, 180 mW/m² at 15 Ma and 160 mW/m² at 0 Ma and 90 mW/m² at 16 Ma, 180 mW/m² at 15 Ma, 180 mW/m² at 10 Ma, 160 mW/m² at 5 Ma and 160 mW/m² at 0 Ma;

- **Orange curve:** simulated %Ro obtained for a heat flow of 120 mW/m² at 16 Ma, 200 mW/m² at 15 Ma and 160 mW/m² at 0 Ma;

- **Blue curve:** simulated %Ro obtained for a heat flow of 130 mW/m² at 16 Ma, 180 mW/m² at 15 Ma and 130 mW/m² at 0 Ma;

- **Yellow curve:** simulated %Ro obtained for a heat flow of 140 mW/m² at 16 Ma, 180 mW/m² at 15 Ma and 160 mW/m² at 0 Ma;

- **Green curve:** simulated %Ro obtained for a heat flow of 160 mW/m² at 16 Ma, 160 mW/m² at 15 Ma and 160 mW/m² at 0 Ma.

The best match between measured and simulated values are obtained for the following scenario (blue curve on Fig. 7b; red on Fig. 7c): a heat flow of around 130 mW/m² before faults activation at 16 Ma and then 180 mW/m² at 15 Ma. Following this adjustment in the heat flow, the Rittershoffen model is considered acceptable.

## 5.3. Calibration of the Scheibenhard conductive thermal model

For the Scheibenhard section, VR data from Robert (1985) are also used (Fig. 8). In addition, %Ro values measured in the well Scheibenhardt 2 published by Böcker (2015), considering data from Teichmüller (1979) and unpublished reports, were also used for calibration. Measured %Ro values reproduce a continuous profile from post-rift formations to the base of the Triassic, from around 0.2 % to 2.5 %. The modelled %Ro trend is slightly shifted to the right of the measurements from the Cenozoic formations, while it is fairly well correlated with the Mesozoic data (Fig. 8). The slight discrepancy between measured and simulated values for the Cenozoic formations may be either due to the post-rift thickness assumptions, or to the position of the Scheibenhardt 2 well further east of the SCB-101 and SCB F102 wells. Since the measured values are better correlated for the main source rocks (Triassic formations), the 2D conductive thermal modelling of Scheibenhard is considered well-calibrated when considering the initial boundary conditions and assumptions (Sections 4.3 and 4.4).

## 5.4. Calibration of the Roeschwoog conductive thermal model

For the Roeschwoog section (well RO1), the %Ro measured values are greater than 0.60 %Ro and increase with depth (Fig. 9). Modelling using the Soultz-sous-Forêt scenario overestimates the observed vitrinite reflectance, except for the shallowest value. The discrepancy between measured and simulated values is linked here to the position of well RO1 relative to the fault blocs, which imply different burial histories (Fig. 4).

This led to the extraction of two pseudo-wells from the Roeschwoog 2D thermal model, within the bloc positioned towards the Pechelbronn sub-basin and the bloc located towards the Rastatt Trough (Fig. 10). The resulting simulated %Ro evolutions are shown in Fig. 10 and are compared with the top and base measured %Ro values of well RO1 (Fig. 9); referred hereinafter as "boundary values". It appears that only %Ro simulated for pseudo-well 1 located in the Pechelbronn sub-basin matches with measured boundary values (Fig. 10). As a result, the paleo-thicknesses of the Chattian-Aquitanian deposits east of the fault (Rastatt Trough) are not considered as they do not reflect the burial history west of the fault. Only the western part of the Roeschwoog section is considered as well-calibrated and investigated hereafter.

## 5.5. Synthesis of conductive thermal modeling results

In summary, the 2D thermal calibration of Soultz-sous-Forêts is considered as satisfactory regarding the implemented initial boundary conditions (Supplementary data) and assumptions (Sections 4.3 and 4.4). The 2D conductive thermal modelling of Rittershoffen is well-calibrated after increasing the heat flow to 130 and 180 mW/m² at 16 and 15 Ma, respectively. These estimates are based on a conductive system only, and are given here in mW/m² only to provide a first order of indication. For Scheibenhard, the slight discrepancy between measured and simulated values may be linked to the 1) position of the well Scheibenhardt 2 in regards to wells SCB-101 and SCB-102, and to the 2) estimated post-rift paleo-thicknesses, which were expected to be greater to the east of the section. However, the model is considered as well-calibrated as adjustments fit better to the source rocks thermal matu-rities (Fig. 8). Finally, concerning the Roeschwoog area, only the western part of the 2D thermal model (pseudo-well 1; Fig. 10) is considered
Rittershoffen (well GRT-1)

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

kinetic parameters from Burnham (2019)

**Fig. 7.** Evolution of %Ro (logarithmic scale) measured in the GRT-1 well (black crosses; Rittershoffen area) and simulated values (red curve; Burnham, 2019) as a function of depth, with the 0.60 %Ro isoline in light gray representing the entrance of oil window (PetroMod©). Error bars: 95 % confidence interval. a. Modelling results for the initial configured heat flow based on Bossennec et al. (2021) and Vallier et al. (2018). b. Results of various simulation tests obtained after adjusting the heat flow from 16 to 0 Ma (unchanged heat flow from 333 Ma to 16 Ma, based on Bossennec et al. (2021). c. Best match results after calibration of the heat flow (increase) from 16 to 0 Ma (unchanged heat flow from 333 Ma to 16 Ma, based on Bossennec et al. (2021).
Scheibenhard
(wells SCB-101, SCB F102, Scheibenhardt 2)

<figure><img src="image_13.png" /><figcaption>**Fig. 8.** Evolution of %Ro (logarithmic scale) measured in wells SCB-101, SCB F102 and Scheibenhardt 2 (crosses; Scheibenhard area) and simulated values (red curve; Burnham, 2019) as a function of depth, with the 0.60 %Ro isoline in light gray representing the entrance of oil window (PetroMod©). Error bars: 95 % confidence interval. *Scheibenhardt 2 well.</figcaption></figure>

as well-calibrated, considering the initial boundary conditions and the initial assumptions (Sections 4.3 and 4.4). The modelling focuses on conduction only, which is calibrated accordingly to the geological evolution of the basin (using organic matter maturity as marker). From faults activation at around 15 Ma, any residual deviation between simulation results and in-well measurements is to be attributed to the effects of heat transfer through convection. The modelling of convection requires more local details (e.g. petrophysical, hydrogeological, fluid chemistry) to simulate the fluid dynamics in the geothermal reservoirs (the fractured granitic basement and the Lower Triassic). Because convective circulations are confined to the base of the model (reservoirs) and to a few specific faults, the convective modelling is considered out of scope of the paper.

# 6. Modelling results and discussions

## 6.1. Interplay between paleo-burial and faults activity

In this study, the observations and interpretations of the seismic profiles reveal that almost all the Pechelbronn sub-basin faults were active only during the post-rift period and that they developed after the Aquitanian sediment deposition, i.e. probably in relation to the mid-Miocene tectonic activity at around 15 Ma (Section 4.4). In addition, the Roeschwoog fault corresponds to the geological boundary between the Pechelbronn sub-basin and the Rastatt Trough. This allows to consider the 1200 m of preserved post-rift 1 sediments at well RO1 as the thickness of sediments deposited in the Pechelbronn sub-basin before erosion. In comparison, Böcker (2015) assumes 250 m for the mid-Miocene erosion but admitted that this erosion was difficult to

Roeschwoog
(well RO1)

<figure><img src="image_14.png" /><figcaption>**Fig. 9.** Evolution of %Ro (logarithmic scale) measured in the RO1 well (crosses; Roeschwoog area) and simulated values (red curve; Burnham, 2019) as a function of depth, with the 0.60 %Ro isoline in light gray representing the entrance of oil window (PetroMod©). RO1 well measurements in red (Robert, 1985) and black (this study).</figcaption></figure>

assess because of post-Oligocene faulting (Hildebrandt, 1986). In addition, Schwarz and Henk (2005) presented a 3D numerical model for the evolution of the URG rift zone and the results indicate that the Cenozoic rift shoulders uplift would be approximately a maximum of 1400 m on the eastern flank of the area studied here (between Strasbourg and Karlsruhe). An equivalent estimation was proposed by Ziegler and Dèzes (2007) in the southern parts of the URG, from which up to 1–1.5 km of sediments were eroded. Moreover, in the southern URG and Swiss Jura mountains, Todorov et al. (1993) propose a maximum Neogene-age erosion of 1000–2000 m. Compared with the literature, the assessment made in this study supported by seismic profiles interpretation and model calibration using vitrinite reflectance appears reasonable (Figs. 6 and 7). The 1200 m of post-rift sediments were then included above the Rupelian source rock in the conductive thermal basin modelling of the Pechelbronn sub-basin.

## 6.2. In-situ hydrocarbon generation

The %Ro measurements presented in Table 1 reveal that Liassic formations have reached the peak oil window (0.7–0.9 %Ro) in well GPK-1 (Soultz-sous-Forêts), the condensate/dry gas (1.4–2.0 %Ro) to dry gas windows (2.0–4.0 %Ro) in well GRT-1 (Rittershoffen), the peak oil window to the condensate to dry gas window in wells SCB-101 and SCB F102 (Scheibenhard) and the gas/condensate (wet gas/minor oil generation; 1.1–1.4 %Ro) to gas/condensate-to-gas windows in well RO1 (Roeschwoog). All measurements show a positive trend with depth, except for the measured %Ro value for Hettangian/Sinemurian in the well SCB F102, which is considerably lower compared to the depth and other recorded values (Table 1). This could be due to oxidation processes at surface, as indicated by the presence of hematite resulting from pyrite alteration in the sample (not shown here). Nevertheless, the measurements are supported by Tmax Rock-Eval (results of this paper and
<figure><img src="image_15.png" /><figcaption>Fig. 10. Position of pseudo wells 1 and 2, at 700 m and 6000 m respectively on the Roeschwoog section, relative to well RO1, with simulated %Ro results (red curve; Burnham, 2019) and limit values measured in well RO1 (red crosses), bottom left and right, compared with all %Ro values measured in well RO1 displayed in the center (PetroMod©). Scales are different for the pseudo-well 2.</figcaption></figure>

<figure><img src="image_16.png" /><figcaption>Fig. 11. Evolution of simulated %Ro (Easy%RoV kinetic model, Burnham (2019)) of Schistes à Poissons (black curve) and Schistes carton (red curve) as a function of time, with the 0.60 %Ro isoline in light gray representing onset of oil window (PetroMod©). Conductive Thermal modelling results for a. the Soultz-sous-Forêts area (well GPK-1). b. the Rittershoffen area (well GRT-1). c. the Scheibenhard area (wells SCB-101 and SCB F102). d. the Roeschwoog area (pseudo well 1).</figcaption></figure>
Espitalié et al., 1988, not shown here) and demonstrate that the Liassic source rocks have reached sufficient levels of thermal maturity to generate oil and gas. In contradiction to Richard (1994), Blümel et al. (1989) and Böcker et al. (2017) who exclude local Mesozoic active source-rocks, this study demonstrates the potentiality of a local petroleum kitchen.

## 6.3. Diachronous hydrocarbon generation history

For a type II kerogen clay-rich source rock, the onset of the oil window is considered to be reached at 0.6 %Ro (Tissot, 1984; Petersen and Hickey, 1987; Sweeney et al., 1987; Tissot et al., 1987; Dembicki, 2009). The thermal maturity evolutions of the two major Mesozoic and Cenozoic source rocks was simulated as a function of time and the results are displayed in Fig. 11.

According to the conductive thermal modelling results of the Soultz-sous-Forêts area (well GPK-1), the Schistes à Poissons (Rupelian source rock) did not reach the oil window before being eroded during the Miocene. In contrast, the Schistes carton (Toarcian source rock) reached the oil window around 27–26 Ma. Maximum maturity was reached between early to mid-Miocene. For the Rittershoffen model (GRT-1), the Rupelian source rock reached the oil window around 18–17 Ma, without increasing in maturity until the present day (%Ro < 0.70). In contrast, the Toarcian source rock entered the oil window around 30–29 Ma, i.e. earlier than at Soultz-sous-Forêts and reached %Ro up to 1.60 (end of oil window) between the early and middle Miocene.

The Rupelian source rock has barely reached the oil window (%Ro ≤ 0.60; Fig. 10) in the Pechelbronn sub-basin and in the western extension of the Rastatt Trough. In contrast, the Mesozoic source rocks reached the oil window in all studied areas and the gas window in Roeschwoog and Rittershoffen (%Ro > 1.50; Fig. 10). The onset of hydrocarbon generation by the Toarcian source rock is estimated at 42.6 Ma in Roeschwoog, 29.7 Ma in Rittershoffen, 30.1 Ma in Scheibenhard and 26.8 Ma in Soultz-sous-Forêts. The onset of hydrocarbon generation is diachronous from east/southeast to west/northwest and may be associated with a higher sedimentation rate in the Rastatt Trough than in the Pechelbronn sub-basin (Fig. 10). This suggests that the Pechelbronn sub-basin was isolated from the Rastatt Trough as early as the syn-rift phase, as

evidenced by the thickness of syn-rift sediments. On average, the onset of hydrocarbon generation in the Pechelbronn sub-basin occurs between 30 and 27 Ma (Fig. 10).

## 6.4. Spatial temperature distribution over geological time

For each calibrated conductive thermal model (Section 5), evolutions of the lithostatic and hydrostatic pressures as well as temperature conditions of the Toarcian source rock were modelled as a function of time in Fig. 12. For all models, temperatures and pressures increase from 180 to 170 Ma following the deposition of the source rock, in relationship to their burial by the deposition of the Middle and Upper Jurassic series. Values remain constant during the sedimentary hiatus, until the end of the Cretaceous. Their values follow a decreasing trend in response to the erosion period from the end of the Paleocene to the beginning of the Eocene (Fig. 12; Supplementary data).

Conductive thermal modelling results from Soultz-sous-Forêts (GPK-1 well; Fig. 12) indicate that temperature and pressure of the Toarcian source rock (Schistes carton) follow the same trend over time. From 40 Ma on, the parameters gradually increase and reach a maximum in the early-mid Oligocene. This maximum decreases very slightly until the middle of the Miocene, the evolution of parameters remains rather constant from mid-Oligocene to mid-Miocene (Fig. 12). Maximum temperature reached by the source rock during this period is around 120 °C and lithostatic and hydrostatic pressures values are 35–40 MPa and 15–20 MPa, respectively (Fig. 12). For the Rittershoffen area (GRT-1 well), pressures follow the same trend over time. Maximum values remain constant from mid-Oligocene to mid-Miocene, and are yet higher than at Soultz-sous-Forêts. The temperature trend is mainly marked by a thermal peak in the early-mid Miocene. At this stage, the Toarcian source rock records a temperature of around 180 °C (Fig. 12). The evolution of temperature and pressure in the Toarcian source rock over time obtained by thermal conductive modelling of the Scheibenhard area is very similar to that of the Soultz-sous-Forêts model (Fig. 12), nonetheless higher values are obtained. The highest temperature values (around 140–150 °C) show almost no evolution between the mid-Oligocene and the mid-Miocene. West of the Roeschwoog section (pseudo-well 1), the same evolution is observed, reaching two maxima

<figure><img src="image_17.png" /><figcaption>**Fig. 12.** Temperature (°C; in red), lithostatic (MPa; in green) and hydrostatic pressures (MPa; in blue) evolutions for the Schistes carton as a function of time in the Soultz-sous-Forêts area (GPK-1 well; a), Rittershoffen area (GRT-1 well; b) and Roeschwoog area (pseudo-well 1; d) as modelled using PetroMod©.</figcaption></figure>
in the early-mid Oligocene and early-mid Miocene (Fig. 12). West of the Roeschwoog section (pseudo-well 1), at early-mid Oligocene and early-mid Miocene, two distinct maxima are reached with no value plateau unlike the other sites. The maximum temperature is reached during the Oligocene (around 180 °C).

The 2D conductive thermal modelling results indicate that the most intense thermal histories were recorded in Rittershoffen and Roeschwoog, yet no positive thermal anomaly is currently known for the latter (Fig. 11). It means that the thermal distribution has spatially evolved over the development of the URG and was controlled by local burial and evolving past heat flow values, at the sub-basin scale. More specifically, the modelling results indicate that the thermal history of Soultz-sous-Forêts and Scheibenhard depend on both the syn-rift burial and the increase in heat flow during the mid-Miocene (15 Ma) (Fig. 11). The thermal maximum recorded by the Toarcian source rock at Rittershoffen and west of Roeschwoog are identical and particularly high (180 °C; Fig. 11), but differently controlled. The thermal history at Rittershoffen mostly depends on the significant increase in temperature from 15 Ma onwards (Figs. 7 and 11), whereas the thermal history of western Roeschwoog depends mostly on the syn-rift burial (Fig. 11). While the heat flow estimated at Rittershoffen at 15 Ma may be questionable, only its considerable increase during post-rift fault activation can explain the measured %Ro. This involves that the heat flow must have been much higher in Rittershoffen in the past (around 15 Ma) than that currently measured in the URG (> 150 mW/m²). In addition, the heat flow in Rittershoffen was higher than in Soultz-sous-Forêts, unlike today (Table 2). It may be suggested that the convective hydrothermal cells system currently responsible for the high heat flow at Soultz-sous-Forêts (Bächler et al., 2003), was located further east 15 Ma ago. This would suggest a migration of the position of hydrothermal cells from east to west over time, in accordance with numerical modelling of heat transfer in the URG as proposed by Le Carlier et al. (1994).

## 7. Conclusions

The basin modelling proposed in this paper brings a geological time frame to the thermal evolution of the central part of the URG. Among the geological constraints to the conductive basin modelling, major challenge was to quantify the erosion events controlling the average Tertiary thickness. Seismic profiles observation and hydrocarbon generation timing analysis indicate that the Pechelbronn sub-basin was isolated from the Rastatt Trough as early as the syn-rift phase. The calibrations of the conductive thermal basin models based on the %Ro measurements indicate that the maximum paleo-burial is of Aquitanian age (post-rift), and the maximum additional cumulative thickness in the Pechelbronn sub-basin is approximately 1200 m (from the top of the Schistes à Poissons to the Aquitanian age sediments). The thermal evolution scenario obtained indicates that the Liassic source-rocks reached the oil window in the Pechelbronn sub-basin and the gas window in Roeschwoog and Rittershoffen (%Ro > 1.5). These results are consistent with the Liassic origin of the oils trapped in the Pechelbronn oilfield reservoirs (Böcker et al., 2017; Tchang-Tchong, 2023).

Regarding the thermal modelling, this study demonstrates that the area of Soultz-sous-Forêts mainly depends on syn-rift burial, rather than on its current heat flow. In contrast, the thermal history in Rittershoffen is mainly influenced by a heat flow value that was considerably higher 15 Ma years ago (approximately 180 mW/m², under the pure conduction hypothesis), compared to the Soultz-sous-Forêts area (150 mW/m²). It implies that the position of the hydrothermal cells, mainly responsible for local heat anomalies, may have changed over time, migrating from east to west in relationship to the redistribution of the heat flow by fluid circulation at the basin scale. Perspective of this work is therefore to focus on convective thermal modelling and fluid flows over the past 15 Ma in the central URG.

## CRediT authorship contribution statement

**Tchang-Tchong Laurie:** Writing – review & editing, Writing – original draft, Visualization, Validation, Software, Methodology, Investigation, Conceptualization. **Michels Raymond:** Writing – review & editing, Validation, Supervision, Resources, Conceptualization. **Beccaletto Laurent:** Writing – review & editing, Validation, Supervision, Methodology, Conceptualization.

## Declaration of competing interest

Laurie Tchang-Tchong reports writing assistance was provided by BRGM. Laurent Beccaletto reports a relationship with Bureau for Geological and Mining Research that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgments

The authors would like to thank ÉS-Geothermie and especially A. Genter for permission to sample well GRT-1 and the French geological survey (BRGM), especially O. Serrano, for the sampling of the wells GPK-1, SCB F102, SCB-101 and RO1. We also thank Schlumberger for providing the PetroMod© academic license. The Université de Lorraine is acknowledged for funding this research through the "Lorraine Université d'Excellence" initiative (DEEPSURF project), reference ANR-15-IDEX-04-LUE. Many thanks to Dr. Thomas Poulet and an anonymous reviewer for their constructive comments and discussions.

## Supplementary materials

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.geothermics.2025.103296.

## Data availability

Data will be made available on request.

## References

* Bächler, D., Kohl, T., Rybach, L., 2003. Impact of graben-parallel faults on hydrothermal convection - Rhine Graben case study. Phys. Chem. Earth, Parts A/B/C 28 (9-11), 431-441.

* Baillieux, P., Schill, E., Edel, J.-B., Mauri, G., 2013. Localization of temperature anomalies in the Upper Rhine Graben: insights from geophysics and neotectonic activity. Int. Geol. Rev. 55 (14), 1744-1762.

* Baillieux, P., Schill, E., Abdelfettah, Y., Dezayes, C., 2014. Possible natural fluid pathways from gravity pseudo-tomography in the geothermal fields of Northern Alsace (Upper Rhine Graben). Geotherm. Energy 2, 1-14.

* Barker, C.E., 1981. Organic geochemistry as a geologic tool. Am. Assoc. Pet. Geol. Bull. 65 (5), 894-894.

* Barker, C.E., 1989. Temperature and time in the thermal maturation of sedimentary organic matter. In: Naeser, N.D., McCulloh, T.H. (Eds.), Thermal History of Sedimentary Basins. Springer, New York, NY.

* Beccaletto, L., Capar, L., Cruz-Mermy, D., Oliviero, G., Elsass, P., Perrin, A., Rupf, I., Nitsch, E., Tesch, J., 2010. The GeORG project - seismic interpretation, structural pattern and 3D modeling of the Upper Rhine Graben - first scientific results. Presented at the Technical Workshop on Geopotential of the Upper Rhine Graben (GeORG), 18 November 2010, Freiburg, Germany.

* Behar, F., Vandenbroucke, M., Tang, Y., Marquis, F., Espitalie, J., 1997. Thermal cracking of kerogen in open and closed systems: determination of kinetic parameters and stoichiometric coefficients for oil and gas generation. Org. Geochem. 26 (5-6), 321-339.

* Berger, J.-P., Reichenbacher, B., Becker, D., Grimm, M., Grimm, K., Picot, L., Storni, A., Pirkenseer, C., Derer, C., Schaefer, A., 2005. Paleogeography of the upper Rhine Graben (URG) and the Swiss Molasse basin (SMB) from eocene to pliocene. Int. J. Earth Sci. 94 (4), 697-710.

* Blaise, T., 2012. Doctoral Dissertation. Université de Lorraine, p. 348.

* Blümel, G., Eder, M., Gerling, P., Ploethner, D., Ranke, U., Trippler, K., 1989. Application of hydraulic theory in petroleum exploration. Erdoel Kohle, Erdgas, Petrochem. 42 (1).
Böcker, J.J., 2015. Petroleum system and thermal history of the Upper Rhine Graben. Implications from organic geochemical analyses, oil-source rock correlations and numerical modelling. Doctoral dissertation. Rheinisch-Westfälischen Technischen Hochschule, Aachen, p. 154.

Böcker, J., Littke, R., Forster, A., 2017. An overview on source rocks and the petroleum system of the central Upper Rhine Graben. Int. J. Earth Sci. 106 (2), 707-742.

Bogaard, P., Wörner, G., 2003. Petrogenesis of basanitic to tholeiitic volcanic rocks from the Miocene Vogelsberg, Central Germany. J. Petrol. 44 (3), 569-602.

Boigk, H., Schöneich, H., 1970. Die tiefenlage der Perm basis im nördlichen teil des Oberrheingrabens. Graben Probl. 27, 48-55.

Bossennec, C., Géraud, Y., Böcker, J., Klug, B., Mattioni, L., Sizun, J.-P., Sudo, M., Moretti, I., 2021. Evolution of diagenetic conditions and burial history in Buntsandstein Gp. fractured sandstones (Upper Rhine Graben) from in-situ δ18O of quartz and 40Ar/39Ar geochronology of K-feldspar overgrowths. Int. J. Earth Sci. 110 (8), 2779-2802.

Bourgeois, O., Ford, M., Diraison, M., Veslud, C., Gerbault, M., Pik, R., Ruby, N., Bonnet, S., 2007. Separation of rifting and lithospheric folding signatures in the NW-Alpine foreland. Int. J. Earth Sci. 96 (6), 1003-1031.

Brun, J., Gutscher, M.-A., DEKORP-ECORS team, 1992. Deep crustal structure of the Rhine Graben from DEKORP-ECORS seismic reflection data: a summary. Tectonophysics. 208 (1-3), 139-147.

Druss, G., 2000. Zur Herkunft der Erdeole im Mittleren Oberrheingraben und Ihre Bedeutung fuer Die Rekonstruktion der Migrationsgeschichte und der Speichergesteinsdiagenese. Doctoral Dissertation, 3831. Universität Erlangen-Nürnberg, Forschungszentrum Jülich. Berichte des Forschungszentrums Jülich, p. 222.

Burnham, A.K., 2019. Kinetic models of vitrinite, kerogen, and bitumen reflectance. Org. Geochem. 131, 50-59.

Chantraine, J., Autran, C., Cavelier, C., Alabouvette, B., Barféty, J., Cecca, F., Clozier, L., Debrand-Passard, S., Dubreuilh, J., Feybesse, J., 1996. Carte Géologique de la France à 1/1 000 000. BRGM Orléans ed.

Châteauneuf, J.-J., Ménillet, F., 2014. Découverte d'une microflore bartonienne dans le Fossé rhénan supérieur : la formation de Mietesheim (Bas-Rhin, Alsace, France). Géol. France (1), 3-20.

Clauser, C., Villinger, H., 1990. Analysis of conductive and convective heat transfer in a sedimentary basin, demonstrated for the Rheingraben. Geophys. J. Int. 100 (3), 393-414.

Cloething, S., Ziegler, P.A., 2007. Tectonic models for the evolution of sedimentary basins, in crust and lithosphere dynamics. In: Treatise on Geophysics, Watts, A.B. (eds), 486-611.

Cohen, K.M., Finney, S.C., Gibbard, P.L., Fan, J.-X., 2013. The ICS international chronostratigraphic chart. Episodes 36, 199-204.

Dembicki Jr, H., 2009. Three common source rock evaluation errors made by geologists during prospect or play appraisals. Am. Assoc. Pet. Geol. Bull. 93 (3), 341-356.

Derer, C.E., Schumacher, M.E., Schäfer, A., 2005. The northern Upper Rhine Graben: basin geometry and early syn-rift tectono-sedimentary evolution. Int. J. Earth Sci. 94 (4), 640-656.

Dèzes, P., Schmid, S.M., Ziegler, P.A., 2004. Evolution of the European Cenozoic Rift System: interaction of the Alpine and Pyrenean orogens with their foreland lithosphere. Tectonophysics. 389 (1-2), 1-33.

Donsimoni, M., 1981. Le bassin houiller lorrain : synthèse géologique. Mém. BRGM 117, 102.

Duringger, P., 1988. Les Conglomerés des Bordures du Rift Cénozoïque Rhénan. Dynamique Sédimentaire et Contrôle Climatique. Doctoral Dissertation. Université de Strasbourg, p. 328.

Duringger, P., Aichholzer, C., Orciani, S., Genter, A., 2019. The complete lithostratigraphic section of the geothermal wells in Rittershoffen (Upper Rhine Graben, eastern France): a key for future geothermal wells. BSGF-Earth Sci. Bull. 190 (1), 13.

Edel, J., Fuchs, K., Gelbke, C., Prodehl, C., 1975. Deep structure of the southern Rhinegraben area from seismic refraction investigations. J. Geophys. 41 (1), 333-356.

Edel, J.-B., Schulmann, K., Rotstein, Y., 2007. The Variscan tectonic inheritance of the Upper Rhine Graben: evidence of reactivations in the Lias, late eocene-Oligocene up to the recent. Int. J. Earth Sci. 96 (2), 305-325.

Ellwanger, D., Gabriel, G., Hoselmann, C., Lämmermann-Barthel, J., Weidenfeller, M., 2005. The Heidelberg drilling project (Upper Rhine Graben, Germany). Quaternaire. Rev.' Assoc. Franç. Pour l'étude Quatern. 16 (3), 191-199.

Espitalié, J., Marquis, F., Barsony, I., Fritz, B., 1988. Diagraphe géochimique du forage géothermique de Soultz-sous-Forêts (GPK1) en Alsace. IFP 35829, 6. Doc. Ref.

Frey, M., Bär, K., Stober, I., Reinecker, J., van der Vaart, J., Sass, I., 2022a. Assessment of deep geothermal research and development in the Upper Rhine Graben. Geotherm. Energy 10, 1-67.

Fries, D., Lebouil, S., Maurer, V., Martin, C., Baujard, C., Ravier, G., Boguais, R., Amari, S., 2022. Lithium extraction through pilot scale tests under real geothermal conditions of the Upper Rhine Graben. Presented at the. In: Proceedings European Geothermal Congress, p. 7.

Fuchs, K., Gehlen, K., Mälzer, H., Murawski, H., Semmel, A., 1983. Plateau uplift: The Rhenish Shield—A case History. Springer Berlin, p. 413.

GeORG project team, 2013. Potentiel géologique profond du Fossé rhénan supérieur. Rapport scientifique et technique du projet Interreg GeORG, Part 1-4; Internet (PDF-document : http://www.geopotenziale.eu).

Grimm, M.C., Wielandt-Schuster, U., Hottenrott, M., Grimm, K.I., Radtke, G., Deutsche Stratigraphische Kommission, 2011. Oberrheingraben. In: Stratigraphie Von Deutschland IX; Tertiär, Teil 1: Oberrheingraben und Benachbarte Tertiärgebiete, 75. Schriftenr. Deut. Ges. Geow. (Hannover), pp. 57-132. -

Grimmer, J., Ritter, J., Eisbacher, G., Fielitz, W., 2017. The late Variscan control on the location and asymmetry of the Upper Rhine Graben. Int. J. Earth Sci. 106 (3), 827-853.

Guillou-Frottier, L., Carré, C., Bourgine, B., Bouchot, V., Genter, A., 2013. Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models. J. Volcanol. Geotherm. Res. 256, 29-49.

Hantschel, T., Kauerauf, A.I., 2009. Fundamentals of Basin and Petroleum Systems Modeling. Springer Science & Business Media, p. 476.

Haimberger, R., Hoppe, A., Schäfer, A., 2005. High-resolution seismic survey on the Rhine River in the northern Upper Rhine Graben. Int. J. Earth Sci. 94, 657-668.

Hemelsdael, R., Averbuch, O., Beccalotto, L., Izart, A., Marc, S., Capar, L., Michels, R., 2023. A deformed wedge-top basin inverted during the collapse of the Variscan belt: the Permo-Carboniferous Lorraine Basin (NE France). Tectonics, 42, e2022TC007668.

Hildebrandt, L., 1986. Die oligozänen Konglomerate von Wiesloch bei Heidelberg. Aufschluss 37, 137-148.

Hinsken, S., Schmalholz, S.M., Ziegler, P.A., Wetzel, A., 2011. Thermo-Tectono-stratigraphic Forward modelling of the Upper Rhine Graben in reference to geometric balancing: brittle crustal extension on a highly viscous mantle. Tectonophysics. 509 (1-2), 1-13.

Kohl, T., Mégel, T., 2007. Predictive modeling of reservoir response to hydraulic stimulations at the European EGS site Soultz-sous-Forêts. Int. J. Rock Mech. Min. Sci. 44 (8), 1118-1131.

Laubscher, H.P., 1987. Die tektonische Entwicklung der Nordschweiz. Ecol. Geol. Helv. 80 (2), 287-303.

Laurent, H., 1974. Etudes préliminaires des possibilités géothermiques de la Basse Alsace, entre Schirrhein et Scheibenhard (Bas-Rhin). BRGM, report 74SGN080GTH, 63 pp.

Le Carlier, C., Royer, J.J., Flores, E.L., 1994. Convective heat transfer at the Soutz-sous-Forêts geothermal site: implications for oil potential. First Break 12 (11), 553-560.

Le Tapyer, M., 2007. Doctoral Dissertation. These de l'Université de Strasbourg, p. 280.

Le Meur, M., Boussafir, M., Le Milbeau, C., Debure, M., Claret, F., Robinet, J.C., Lerouge, C., 2021. Organic matter oxidation of the Tégulines Clay formation, (Paris Basin, France): spatial heterogeneities. Appl. Geochem. 134, 105093.

Lemgruber-Traby, A., Bossennec, C., Béthune, G., Souque, C., Divies, R., Van der Vaart, J., Bär, K., Sass, I., 2023. Basin-scale 3D modelling of the northern Upper Rhine Graben: insights into basement fault-related geothermal flow pathways. Geoenergy 1 (1) geenergy2023-002.

Lutz, M., Cleintuar, M., 1999. Geological results of a hydrocarbon exploration campaign in the southern Upper Rhine Graben (Alsace Centrale, France). Bull. Angew. Geol. 4, 3-80.

Lutz, H., Lorenz, V., Engel, T., Häfner, F., Haneke, J., 2013. Paleogene phreatomagmatic volcanism on the western main fault of the northern Upper Rhine Graben (Kisselwörth diatreme and Nierstein-Astheim Volcanic System, Germany). Bull. Volcanol. 75 (7), 1-11.

McKenzie, D.P., 1978. Some remarks on the development of sedimentary basins. Earth. Planet. Sci. Lett. 40 (1), 25-32.

Ménillet, F., Durand, M., Genter, A., Party, J., 2015. Notice explicative de la carte géologique de France (1/50 000). Feuille Haguenaue, 2e éd. BRGM, Orléans.

Naeser, N.D., McCulloh, T.H., 1989. Thermal History of Sedimentary Basins: Methods and Case Histories. Springer-Verlag, New York.

Perner, M.J., 2018. Doctoral Dissertation. Universität Heidelberg, p. 115.

Person, M., Garven, G., 1992. Hydrology constraints on petroleum generation within continental rift basins: theory and application to the Rhine Graben. Am. Assoc. Pet. Geol. Bull. 76 (4), 468-488.

Petersen, N., Hickey, P., 1987. California Plio-Miocene oils: evidence of early generation. In: exploration for heavy crude oil and natural bitumen. AAPG Stud. Geol. 25, 351-359.

Ploethner, D., 1988. Entwicklung und anwendung einer erdölgeologisch-geochemischen explorationmethode unter besonderem Berücksichtigung der Hydraulik im Pechelbronner Gebiet-Flachbohrprogramm: temperatur- und Hydrochemiedaten. Bundesanstalt für Geowissenschaften und Rohstoffe - Hannover (FRG). BMFT-Forschungsvorhaben, 032 6476 A.

Poelchau, H., Baker, D., Hantschel, T., Horsfield, B., Wygrala, B., 1997. Basin simulation and the design of the conceptual basin model. Petrol. Basin Evolut. 3-70.

Pribnow, D., Schellschmidt, R., 2000. Thermal tracking of upper crustal fluid flow in the Rhine graben. Geophys. Res. Lett. 27 (13), 1957-1960.

Richard, A., 1994. Petroleum exploration in the French Rhine Graben. Hydrocarbon and Petroleum Geology of France. Springer Berlin Heidelberg, pp. 361-363.

Robert, P., 1985. Histoire géothermique et diagenese organique. Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 8, 345.

Robert, P., 1988. Organic Metamorphism and Geothermal history: Microscopic Study of Organic Matter and Thermal Evolution of Sedimentary Basins. Reidel publishing company, p. 291.

Röhl, H.-J., Schmid-Röhl, A., Oschmann, W., Frimmel, A., Schwark, L., 2001. The Schistes cartons (Lower Toarcian) of SW-Germany: an oxygen-depleted ecosystem controlled by sea level and palaeoclimate. Palaeogeogr. Palaeoclimatol. Palaeoecol. 165 (1-2), 27-52.

Roll, A., 1979. Versuch einer Volumenbilanz des Oberrheintalgrabens und seiner Schultern. Geol. Jahrbuch/A: Allgemeine Region. Bundesrepubl. Deutschland Nachbargebiete, Tekton., Stratigraph., Paläontol. 52, 82.

Rotstein, Y., Schaming, M., 2008. Tectonic implications of faulting styles along a rift margin: the boundary between the Rhine Graben and the Vosges Mountains. Tectonics. 27 (2).
Rotstein, Y., Schaming, M., 2011. The Upper Rhine Graben (URG) revisited: miocene transtension and transpression account for the observed first-order structures. *Tectonics*. 30 (3).

Roussé, S., 2006. Doctoral Dissertation. Université de Strasbourg, p. 474.

Sanjuan, B., Gourcerol, B., Millot, R., Rettenmaier, D., Jeandel, E., Rombaut, A., 2022. Lithium-rich geothermal brines in Europe: an up-date about geochemical characteristics and implications for potential Li resources. *Geothermics*. 101, 102385.

Schellschmidt, R., Clauser, C., 1996. The thermal regime of the Upper Rhine Graben and the anomaly at Soultz. *Zeitschr. Angew. Geol.* 42 (1), 40–44.

Schuler, M., 1990. Environnements et paléoclimats paléogènes. *Palynologie et biostratigraphie de l'Eocène et de l'Oligocène inférieur dans les fossés rhénan, rhodanien et de Hesse. Doc. B.R.G.M* (190), 503.

Schumacher, M.E., 2002. Upper Rhine Graben: role of preexisting structures during rift evolution. *Tectonics*. 21 (1), 6–1.

Schwarz, M., Henk, A., 2005. Evolution and structure of the Upper Rhine Graben: insights from three-dimensional thermomechanical modelling. *Int. J. Earth Sci.* 94, 732–750.

Sinclair, H., Coakley, B., Allen, P., Watts, A., 1991. Simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion: an example from the central Alps. *Tectonics*. 10 (3), 599–620.

Sissingh, W., 1998. Comparative tertiary stratigraphy of the Rhine Graben, Bresse Graben and Molasse Basin: correlation of Alpine foreland events. *Tectonophysics*. 300 (1–4), 249–284.

Sissingh, W., 2006. Syn-kinematic palaeogeographic evolution of the West European Platform: correlation with Alpine plate collision and foreland deformation. *Netherlands J. Geosci.* 85 (2), 131–180.

Sittler, C., 1965. Le Paléogène des fossés rhénan et rhodanien. *Etudes sédimentologiques et paléoclimatiques. Mém. Serv. Carte Géol. Alsace Lorraine* (24), 329.

Sittler, C., 1967. Le soubassement et le remplissage sédimentaire du Fossé Rhénan au niveau du bassin de Pechelbronn et du seuil d'Erstein. *Coupes géologiques à travers le Fossé Rhénan. The Rhinegraben Progress Report, Strasbourg*, 69–80.

Sittler, C., Ollivier-Pierre, M.-F., 1994. Palynology and palynofacies analyses: some essential clues to assess and identify West-European tertiary depositional environments in terms of relative high or lowstands. Application to the case of three eocene and oligocene sections in France. *Bull. Centres Rech. Explor.-Prod. Elf-Aquit.* 18 (2), 475–488.

Stahmer, G., 1980. Stratigraphie des Oberrheingraben-Tertiärs und seiner nördlichen fortsetzungen. *Wintershall AG (Internet Bericht), Kassel*.

Sweeney, J., Burnham, A.K., Braun, R., 1987. A model of hydrocarbon generation from type I kerogen: application to Uinta Basin, Utah. *Am. Assoc. Pet. Geol. Bull.* 71 (8), 967–985.

Tchang-Tchong, L., 2023. Les hydrocarbures comme marqueurs de thermicité et de transfert de fluides en contexte d'anomalie géothermique : le cas du sous-bassin de Pechelbronn (Fossé Rhénan). *Doctoral Dissertation. Université de Lorraine*, p. 363.

Tchang-Tchong, L., Michels, R., Beccaletto, L., Bossennec, C., Lorgeoux, C., Faure, P., 2023. Pre- to early-rift thermal conditions of the Upper Rhine Graben using geological and organic geochemical controls. *Mar. Pet. Geol.* 151, 106202.

Tissot, B., 1984. Recent advances in petroleum geochemistry applied to hydrocarbon exploration. *Am. Assoc. Pet. Geol. Bull.* 68 (5), 545–563.

Tissot, B., Pelet, R., Ungerer, P., 1987. Thermal history of sedimentary basins, maturation indices, and kinetics of oil and gas generation. *Am. Assoc. Pet. Geol. Bull.* 71 (12), 1445–1466.

Todorov, I., Schegg, R., Wildi, W., 1993. Thermal maturity and modelling of mesozoic and cenozoic sediments in the south of the Rhine Graben and the Eastern Jura (Switzerland). *Eclog. Geol. Helv.* 86 (3), 667–692.

Vallier, B., Magnenet, V., Schmittbuhl, J., Fond, C., 2018. THM modeling of hydrothermal circulation at Rittershoffen geothermal site, France. *Geotherm. Energy* 6, 1–26.

Villemin, T., Bergerat, F., 1987. L'évolution structurale du fossé rhénan au cours du Cenozoique; un bilan de la deformation et des effets thermiques de l'extension. *Bull. Soc. Géol. France* 3 (2), 245–255.

Von Eller, J.-P., Sittler, C., 1974. Les Vosges et le Fossé Rhénan. *Vieux Massifs et Grands Bassins sédimentaires, J. Debelmas edition, Géologie de La France* 1, 63–104.

Wannesson, J., 1998. Technical report. *Institut Français du pétrole*, p. 62.

Waples, D.W., Kamata, H., Suizu, M., 1992a. The art of maturity modeling. Part 1: finding a satisfactory geologic model. *Am. Assoc. Pet. Geol. Bull.* 76 (1), 31–46.

Waples, D.W., Suizu, M., Kamata, H., 1992b. The art of maturity modeling. Part 2: alternative models and sensitivity analysis. *Am. Assoc. Pet. Geol. Bull.* 76 (1), 47–66.

Ziegler, P.A., 1987. Late cretaceous and cenozoic intra-plate compressional deformations in the Alpine foreland—a geodynamic model. *Tectonophysics*. 137 (1–4), 389–420.

Ziegler, P.A., 1990. Geological atlas of western and central Europe. *Shell Int. Pet. Maatschappij. Geol. Soc. Publ. House, Bath, UK*, p. 239.

Ziegler, P.A., 1992. European cenozoic rift system. *Tectonophysics*. 208 (1–3), 91–111.

Ziegler, P.A., Dèzes, P., 2007. Cenozoic uplift of Variscan Massifs in the Alpine foreland: timing and controlling mechanisms. *Glob. Planet. Change* 58 (1–4), 237–269.

Yalcin, M., Littke, R., Sachsenhofer, R., 1997. Thermal history of sedimentary basins. *Petrol. Basin Evolut.* 71–167.

Zucca, J., 1984. The crustal structure of the southern Rhinegraben from re-interpretation of seismic refraction data. *J. Geophys.* 55 (1), 13–22.