Work

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

Year: 2025

Type: article

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. Therefore, this study investigates the interplay between URG 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 plus 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) to the Aquitanian sediments. Toarcian source-rock 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 nowadays 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 of heat flow in others, e.g. in Rittershoffen. Moreover, it appears that the heat flow must have been considerably higher (around 180 mW/m²) during faults activation (around 15 Ma) in the Rittershoffen area, compared to Soultz-sous-Forêts and present-day surface heat flows (maximum values around 150 mW/m² across the URG). Changes in local heat flows are attributed to east-west migration of hydrothermal cells positions through time from 15 Ma on in relationship to fluid circulation at basin scale. These results provide new insights into the thermal evolution of the URG and its implications for sub-surface resources exploration.

Source: Geothermics

DOI: 10.1016/j.geothermics.2025.103296

Authors: Tchang-Tchong Laurie, Michels Raymond, Beccaletto Laurent

Institutions: Centre National de la Recherche Scientifique, Laboratoire Interdisciplinaire des Environnements Continentaux, GeoRessources, Université de Lorraine, Bureau de Recherches Géologiques et Minières

Language: English

Topic: Hydrocarbon exploration and reservoir analysis

Subfield: Mechanics of Materials

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,220

Funders: Université de Lorraine, Agence Nationale de la Recherche, Bureau de Recherches Géologiques et Minières