TS10.2

Flexural foreland basins represent first-order geological archives that preserve the record of orogenic processes. These detrital archives provide critical insights into tectonic, climatic and environmental evolution as well as variations in source lithologies, isostasy, eustasy and dynamic lithospheric processes. In this study, we combine published geological data (e.g., facies analysis, magnetostratigraphy, sediment provenance, and carbon and oxygen isotopic records from authigenic minerals) with new zircon U-Pb geochronologic and zircon and apatite (U-Th)/He thermochronologic data from the southern foreland basin of the Alborz Mountains in northern Iran. This orogen, resulting from the Neogene Arabia-Eurasia collision zone, experienced topographic growth and exhumation since ~20 Ma and foreland deposition of a thick pile (> 7 km) of continental red beds.

The foreland-basin fill consists of three major systematic coarsening-upward cycles that each exhibits fine-grained siliciclastic strata at the base with high sediment accumulation rates and younger detrital zircon U-Pb and (U-Th)/He ages (mostly Eocene), followed by coarse-grained sedimentary strata with decreased sediment accumulation rates and older detrital zircon U-Pb and (U-Th)/He ages (> 100 Ma).

The base of each cycle is interpreted as a pulse of enhanced subsidence driven by tectonic loading associated with the growth of new thrust sheets experiencing erosional unroofing. The top of each cycle is interpreted to reflect wanning tectonic subsidence in response to local intra-basinal uplift (cycle 1) as documented by the sedimentary stratal pattern; uplift of the proximal foreland (cycle 3) as suggested by the age distribution of the detrital zircon U-Pb ages, the shift from fluvial to alluvial fan deposits and recycled apatite (U-Th)/He ages from the deepest exhumed red beds. Within these systematic trends, the top of cycle 2 represents an exception as it appears to record an enhanced phase of sediment supply triggered by wetter climatic conditions as documented by oxygen isotope data from paleosols samples.

Overall, our multidisciplinary approach provides a comprehensive overview of the history of a collisional foreland basin, from the forcing mechanisms controlling its stratigraphic architecture and sedimentary composition to its final incorporation into the orogenic wedge associated with basin uplift and erosion.

How to cite: Ballato, P., Stockli, D. F., Hassanzadeh, J., Stockli, L. D., and Strecker, M. R.: The life cycle of a foreland basin: Insights from the Alborz Mountains (Arabia-Eurasia collision zone), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7383, https://doi.org/10.5194/egusphere-egu22-7383, 2022.

Apatite fission track (AFT) thermochronology can resolve thermal histories over a temperature window that spans 50–150°C. Herein, we present a case study from the Peel Plateau, a foreland basin of the Mackenzie Mountains, northern Canadian Cordillera, where we compare three interpretations from a single AFT sample: 1) the central age, and thermal history modelling of 2) a mono-kinetic population and 3) a multi-kinetic population. The AFT sample is derived from a lithic wacke with an Albian depositional age and yields an AFT central age of 67 ± 9 Ma (n: 39). Despite central ages often being interpreted to reflect a sample’s 'cooling age,' laboratory experiments have demonstrated that fission tracks anneal over a wide temperature range, corresponding to the partial annealing zone (PAZ). AFT ages from samples that have undergone multiple burial and exhumation events likely represent partial annealing due to their protracted residence in the PAZ and require thermal history modelling to derive a meaningful geologic interpretation. It is unlikely the Peel Plateau experienced a simple thermal history with rapid cooling through the PAZ, as a regional unconformity separates the Albian and Cenomanian strata across much of the region. Thus, the central age does not necessarily reflect a meaningful thermal event. Thermal modelling the data as a mono-kinetic population predict peak burial temperatures of 118–166°C at 65–92 Ma, however, the sample fails the χ², indicating it does not comprise a single statistical age population. Intra-sample age dispersion is often indicative of samples that comprise multi-kinetic population and grain specific chemistry is known to strongly influence apatite’s annealing kinetics. Most notably apatite with high F content will undergo thermal annealing at lower temperatures than apatite with high Cl content, although numerous other elements (e.g. OH, Mn, Fe) are known to effect annealing kinetics. The r_mro parameter was developed through laboratory annealing experiments, and accounts for compositional controls on apatite’s kinetic behaviour. Apatite grain chemistry was measured via EMPA methods to calculate r_mro values and used to separate AFT samples into two kinetic populations (resulting in pooled ages of 36 ± 5 Ma and 103 ± 12 Ma) that both pass the χ² test. Pooled ages incorporate information of the grains’ pre-depositional history and U-Pb dating can serve as an additional tool to decipher between different kinetic populations. These populations then act as independent thermochronometers capable of resolving different temperature windows. Compared to thermal history model results from mono-kinetic data, the multi-kinetic model predicts significantly lower burial temperatures of 83–93°C, which may have occurred over a longer duration (33–88 Ma). The central age for this sample overlaps with the timing of peak burial predicted by the multi-kinetic model, therefore does not inform us about the cooling history. Ultimately, the purpose of this study is to highlight the importance of assessing multi-kinetic behaviour in sedimentary samples, as these interpretations provide statistically significant age populations and robust thermal history models. Thermal history models that ignore multi-kinetic behaviour may lead to erroneous geologic interpretations.

How to cite: Spalding, J., Schneider, D., and Powell, J.: Central ages, mono-kinetic, or multi-kinetic? Assessing detrital AFT thermochronology in a Cretaceous foreland basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-61, https://doi.org/10.5194/egusphere-egu22-61, 2022.

The Froan Basin, located on the proximal platform area on the Mid-Norwegian Continental Shelf, contains petroleum-bearing Upper Jurassic syn-rift deposits. Additional isolated Upper Jurassic shallow marine sand bodies have been identified on the Frøya High, but the platform area remains poorly understood in terms of its Late Jurassic tectono-stratigraphic evolution. Improving our understanding, and in particular how fault activity and rift-shoulder uplift influenced rift physiography and the presence of shallow marine reservoirs, is crucial when assessing hydrocarbon prospectivity. In this study, we present a model for the Late Jurassic rift development of the Froan Basin and Frøya High based on seismic interpretation, well data, and reverse subsidence modelling. We show that during the Late Jurassic to Early Cretaceous, major footwall uplift and exposed the western margin of the Froan Basin and Frøya High formed an intra-rift footwall island. Shallow marine areas to the east, immediately adjacent to the footwall island, accumulated shoreface sediments supplied from the eroded footwall. We therefore suggest that the extent of the Late Jurassic shallow marine system was controlled by the magnitude of footwall uplift and geomorphology of the western margin of the platform area.

How to cite: Nakken, L., Chiarella, D., and Jackson, C. A.-L.: Development of a Late Jurassic shallow marine system controlled by footwall uplift in the Froan Basin and Frøya High, offshore Mid-Norway, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10007, https://doi.org/10.5194/egusphere-egu22-10007, 2022.

Raman Spectroscopy on Carbonaceous Material (RSCM) approach is commonly used to calculate thermal peaks recorded by rocks. A first calibration of the RSCM was developed to measure temperatures ranging from 330°C to 640°C (Beyssac et al., 2002). Its applicability was later expanded to lower temperatures from 200°C to 350°C (Lahfid et al., 2010). Here, we apply the RSCM approach to Digne Nappe area - thrust front of the SW Alps - in order to evaluate the thermal evolution of the sub-Alpine domain from rift to the present. About 150 temperatures have been obtained along seven continuous stratigraphic sections sampled along the strike the whole Digne thrust sheet. The base of the Digne thrust sheet (i.e. the Lias syn-rift carbonates) shows temperatures ranging from 250°C to 330°C. These temperatures are 200-240°C in post-rift marls dated to Callovian-Oxfordian and rapidly drop upsection in the Kimmeridgian-Tithonian carbonates and younger Cretaceous rocks to temperatures below 100-120°C. While these temperatures are seen to decrease from bottom to top we note the lack of well-defined apparent geothermal gradients. One of our section (Serre-Ponçon) structurally positioned beneath the Embrunais-Ubaye thrust sheets is remarkable because the temperatures are rather homogeneous, ranging between 300°C and 350°C along the whole 5km-thick sedimentary pile from the Lias until the Eocene. The regional dataset suggests that the thermal history of the sub-Alpine fold-and-thrust belts varies along-strike and requires the succession of several thermal events. The drop of temperatures observed in the Late Jurassic sediments is interpreted to be related to increasing heat flow during crustal thinning associated to the formation of the Alpine Tethys rifted margin.  The high temperatures observed along the Serre-Ponçon specifically indicate a burial beneath the Embrunais-Ubaye thrust sheets during Alpine orogeny, possibly combined with high geothermal gradients inherited from the Mesozoic Alpine Tethys thinning phase.

How to cite: Célini, N., Mouthereau, F., Lahfid, A., Gout, C., and Callot, J.-P.: Tectono-thermal evolution of the External Western Alps (France): evidence for rift-related thermal event, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3510, https://doi.org/10.5194/egusphere-egu22-3510, 2022.

The Midland Valley Basin of Scotland (MVS) is a major NE-SW trending, fault-bounded sedimentary basin in central Scotland, UK, comprised predominantly of Carboniferous and Devonian sedimentary rocks. Changing palaeo-environments of the MVS produced alternating successions of sandstone, siltstone, mudstone, limestone and coal. The MVS also experienced folding, fault inversion and development of a widespread unconformity during the latest Carboniferous culmination of the Variscan Orogeny and minor tectonic events thereafter. The MVS’ geological resources played a major role in driving Scotland’s economic, industrial, and cultural development in the 19^th - 20^th. The region was heavily exploited for coal and hydrocarbon energy resources and material for construction, manufacturing, and agriculture. The MVS basin remains as relevant in the 21^st century having been identified as a viable source of low-carbon geo-energy resources (e.g., geothermal energy) and potential for subsurface energy storage (Heinemann et al., 2019).

While the geology of the MVS has been well-studied, thermal and burial history reconstructions have typically relied on techniques focused on the maturation of organic matter (e.g., vitrinite reflectance, VR), which lack quantitative information on timing. Moreover, tracing sediment provenance can be challenging but crucial for understanding the tectonic evolution of the surrounding source region. Here, we present the results of a geochronological and thermochronological investigation of the MVS basin designed to better understand sediment pathways to the basin from surrounding upland regions and the post-depositional thermal history of the MVS. Our data includes zircon and apatite U-Pb data and apatite fission-track (AFT) data from across the basin and AFT data from a UK Geoenergy Observatories borehole in Glasgow.

With our U-Pb data, we identify distant source areas in Greenland, more local source areas in the Scottish Highlands, and recycling of older sedimentary rocks and reworked material in the basin that change through the tectono-magmatic evolution of the basin. Our AFT data and associated thermal history modelling identify three main thermal events: i) Carboniferous-Permian heating; ii) Permian-Mesozoic cooling, and iii) relatively rapid Cenozoic cooling (McKenna, 2021; Hattie, 2021). These are attributed to post-Carboniferous burial followed by post-Permian exhumation. However, ambiguity in some of our models suggests some heating in the Mesozoic may have occurred and, due to the limitations on the temperature sensitivity of the AFT technique, the timing and rate of Cenozoic cooling is poorly resolved. Through our modelling we explore the influence changing palaeo-geothermal gradients has on our thermal history and whether the lower temperature thermochronometer apatite (U-Th)/He can better resolve the most-recent cooling event.

Heinemann, N., Alcalde, J., Johnson, G., Roberts, J. J., McCay, A. T., & Booth, M. G. (2019). Low-carbon GeoEnergy resource options in the Midland Valley of Scotland, UK. Scottish Journal of Geology, 55(2), 93-106.

McKenna, Eamon (2021) The Provenance and thermal histories of the Carboniferous Midland Valley of Scotland, PhD thesis, University of Glasgow.

Hattie, Andrew (2021) Constraining the post-burial history of the central Midland Valley of Scotland using apatite fission track analysis: implications for geothermal energy. MSc(R) thesis, University of Glasgow.

How to cite: Wildman, M., Persano, C., McKenna, E., Hattie, A., and Monaghan, A.: Geology, Geochronology and Geoenergy of Sedimentary Basins: Insights from the Midland Valley of Scotland, UK, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8433, https://doi.org/10.5194/egusphere-egu22-8433, 2022.

The measurements of soil erosion, sediment transport, and soil deposition due to the tectonic activity regions retard the river basin development. The tectonic activity assessment in this area requires the identification of minimum eroded volume (MEV) and the soil loss (Sl) amount. The MEV, LS, and Hi indices have been used to develop relative tectonic activity Index (RTI) to identify probable zones of Hi, MEV, and SL in the Diyala River Basin (DRB). The results show that the north, north-eastern, and northwestern parts of the (DRB) are situated in the high (RTI) zone. The TIN model is used for estimating the MEV in the DRB and the (RUSLE) model is used for estimating the soil loss in the DRB. The MEV results in the DRB vary from 0 to 845 m3 in some areas. The result of soil loss in the DRB is varied from a minimum value of zero to a maximum of 91.34 t/h/y in some areas. The spatial distribution of MEV and SL in the (DRB) is classified into five types (Low Tectonic Activity, Slight Tectonic Activity, Moderate, High, and Extremely Tectonic Activity). From the results, it was observed that about 25.3% and 24.2% of the total study area are located in the very high relative tectonic activity and low relative tectonic activity zones, respectively. The large percentage of soil loss areas are 28.6% and 26.5% of the total study area are located in the very slight and slight, respectively.

How to cite: Ali, M.: The tectonic  activity assessment using minimum eroded volume and soil loss in Diyala river basin area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12468, https://doi.org/10.5194/egusphere-egu22-12468, 2022.