The research, led by geologists working with the Piemonte Geological Map and a network of seismic sections crossing the whole basin, integrates surface mapping with subsurface data for the first time at a truly regional scale. The team traced the basin’s sedimentary successions across six distinct sub-domains, from the Torino Hill and Monferrato in the north to the Langhe, Alto Monferrato and Borbera-Grue in the south and east. By tying outcrop geology to roughly three hundred kilometres of seismic multipanels, the authors reconstructed how the basin evolved from a retroforeland depression behind the rising Western Alps into a thrust-top basin riding on the frontal thrusts of the young Apennine belt.

The story begins in the middle to late Eocene, when the collision between the European and Adriatic plates was still in its early stages. As the Alpine orogen started to exhume its high-pressure metamorphic rocks, the flexural load of the growing mountain chain bent the lithosphere and created space for sediment. On the external side of the belt, the Alpine Foreland Basin received continental and shallow-marine deposits, while on the internal side a large retroforeland realm developed over the deformed Ligurian units. The earliest sediments of the Tertiary Piemonte Basin, deep-water marls known as the Marne di Monte Piano, rest unconformably on these non-metamorphic Ligurian successions, marking the first chapter of a basin that would persist for more than thirty million years.

What makes the basin remarkable is its sensitivity to tectonic change. The sedimentary fill is punctuated by a series of regional-scale unconformities, labelled D0 through D7, each one recording a major geologic event that can be correlated across the entire basin and, in many cases, into the neighbouring EpiLigurian basins of the Northern Apennines and the Gonfolite Basin of the Southern Alps. These unconformities bound unconformity-bounded stratigraphic units, or synthems, whose ages and distributions the authors mapped in detail using the Piemonte Geological Map as a continuous regional framework. The result is a chronostratigraphic architecture that reads like a seismograph of Mediterranean geodynamics.

The first major reorganisation came in the early Rupelian, around thirty-four million years ago. As the Adriatic microplate moved westward and the Ligurian rollback subduction initiated, a transtensional regime developed in the inner side of the uplifting Alpine belt. High-angle synsedimentary faults dissected the basin substratum into a mosaic of fault blocks, and coarse continental to shallow-marine conglomerates and sandstones of the Molare, Cardona and Savignone formations began to accumulate. These deposits, the study notes, are the distinguishing feature of the Tertiary Piemonte Basin, marking the onset of erosion synchronous with the rapid exhumation of Alpine metamorphic rocks very close to the rising mountain chain, in a retroforeland geodynamic setting that the more distal EpiLigurian successions never shared.

By the late Rupelian and Chattian, the basin entered a subsidence-dominated phase. The Ligurian Alps experienced more than four kilometres of subsidence between thirty and twenty-six million years ago, and deep-water hemipelagic marls with interbedded re-sedimented sandstone bodies accumulated across the basin. This quiet period ended abruptly in the early Burdigalian, around twenty million years ago, when the direction of motion of the Adriatic indenter shifted from northwest to west-northwest. The resulting oblique convergence triggered a major contractional event that inverted many of the basin’s earlier structures, uplifted its margins, and carved the regionally extensive D2 unconformity. Shallow-water carbonate ramps of the Pietra da Cantoni and Visone formations then spread over the deformed Oligocene slope sediments, a dramatic reshaping that correlates with coeval tectonic events recorded in the Gonfolite Basin and the EpiLigurian domains.

The late Burdigalian brought a second, even more profound inversion. The main depocentre shifted abruptly to the southwest, into the Langhe region, and the entire basin drowned. More than seven hundred metres of westerly-derived turbidites of the Cortemilia Formation spread across the basin floor, while the formerly active sediment sources in the Ligurian Alps gradually gave way to new sources in the west as the Alpine axial belt continued to exhume. From this point onward, the Tertiary Piemonte Basin was no longer simply a retroforeland depression behind the Alps. It had become an episutural basin on top of the northeast-vergent Apennine tectonic belt, its fate now tied to the northeastward propagation of the Apennine thrust front rather than to the Alpine collision alone.

The Miocene chapters record this transition in ever-sharper detail. In the Langhian and Serravallian, shelf systems prograded from both the western and eastern basin margins, progressively reducing the extent of the deep-water depocentre. By the Tortonian, the basin had reached its final configuration as a confined thrust-top basin bordered by the Torino Hill-Monferrato structural high, which now separated it from the ancestral Padane foredeep to the north. The Messinian Salinity Crisis then left its unmistakable signature: selenite gypsum of the Vena del Gesso Formation accumulated in shallow marginal basins, and when an intra-Messinian tectonic pulse reactivated the Apennine thrust front, the primary evaporites were dismantled and re-sedimented as chaotic gravity-flow deposits of the Valle Versa Complex, bound below by the regionally extensive D5 unconformity.

The seismic data add a crucial third dimension to this story. The multipanels reveal that the basin’s outcrop belts, separated at the surface by wide areas of Pliocene and Quaternary cover, are physically continuous in the subsurface. Beneath the Alessandria Basin, the sections image long-lived depocentres confined by prominent structural highs shaped by compressional deformation of a reflective Ligurian substratum, as well as polyphasic flower structures where the Grognardo deformation zone intersects east-west high-angle faults. The sections also document two major depocentre shiftings, one of late Burdigalian age and another of intra-Langhian age, confirming that the basin’s history was one of repeated inversion and migration rather than steady subsidence in a single place.

The study’s most provocative conclusion concerns the nature of that subsidence. Previous subsidence curves for the basin, the authors argue, were distorted by the inclusion of Pliocene and Quaternary deposits that belong to an entirely new generation of basins born after the intra-Messinian tectonic event. When the record is restricted to the Oligocene-Miocene life of the basin, it becomes clear that effectively continuous subsidence occurred only in the Langhe sub-domain, while the basin margins experienced repeated uplift and inversion. This suggests, the team argues, that large-scale far-field stresses and crustal bending may have been less important during the Oligocene and Miocene than the local dynamics of fault-bounded basins formed in the Alpine retroforeland setting. The Tertiary Piemonte Basin, in other words, was not a passive flexural sag but an active, mixed-mode basin whose complex history was shaped by the interplay of Alpine collision, Apennine subduction, and the anticlockwise rotation of the entire Alps-Apennines junction zone. As the Mediterranean’s tectonic plates continue their slow collision, the basin’s sedimentary archive remains the most complete witness to how two mountain belts grew into one integrated orogenic system.

Subject of Research: Tertiary Piemonte Basin sedimentary record of the Alps-Apennines orogenic interference zone in northwest Italy

Article Title: One basin for two orogens

Article References: d’Atri, A., Irace, A., Piana, F., Rossi, M., & Bertok, C. (2026). One basin for two orogens. Swiss Journal of Geosciences, 119, 197-248. https://doi.org/10.3897/sjg.119.184128

Image Credits: AI Generated

DOI: 10.3897/sjg.119.184128

Keywords: Tertiary Piemonte Basin, Alps, Apennines, orogeny, sedimentary basins, unconformities, Adria-Europe collision, Messinian Salinity Crisis, seismic stratigraphy, Piemonte, tectonics, geology

In a study published in the Bulletin of Earthquake Engineering, Anabella Cotovanu, Elisei Cojan and Radu Vacareanu of the Technical University of Civil Engineering Bucharest and the Military Technical Academy Ferdinand I present a unified framework that decomposes the variability of Vrancea ground motions into source, path and site contributions. Their conclusion is striking: the apparent anomalies that have caused Vrancea to be treated as an exception and excluded from global comparative studies do not reflect fundamentally different physics. They arise from pronounced structural heterogeneity and the strong interdependence of source, path and site effects, which previous approaches failed to separate coherently.

The scale of the problem becomes clear when you consider how divergent the published estimates of key parameters have been. Stress drop, a measure of how much energy an earthquake releases per unit of fault area, has been variously reported for major Vrancea events at around 50 bar, 100 to 200 bar, as high as 850 bar statically and 950 to 1400 bar dynamically, and in the range of 300 to 1200 bar by researchers using empirical Green’s function methods. One influential series of analyses by Oth and colleagues employed stress-drop values roughly twenty times higher than commonly adopted reference values simply to make their models consistent with observations. Stress drop, in other words, had effectively become a correction dial rather than a physically constrained quantity.

The situation was hardly better for wave propagation. The literature contains six different attenuation functions describing how ground-motion amplitudes decay with distance outside the Carpathian Arc, split into two camps based on contradictory assumptions about geometrical spreading, with one group assuming amplitude decay proportional to the inverse of distance and the other to the inverse square root. Seismic refraction profiles from the VRANCEA99 and VRANCEA2001 experiments and the CALIXTO tomography project revealed why: the crust and upper mantle beneath the region are dramatically heterogeneous, with the asthenosphere lying at very different depths on either side of the arc, and sedimentary strata in the Focsani Basin bent to depths exceeding 30 kilometers.

Then there is the data problem, which is arguably the most severe constraint of all. Since the beginning of the twentieth century, Vrancea has produced fourteen earthquakes with moment magnitudes of at least 6.3, yet only four have been instrumentally recorded: the events of 1977, 1986, and the two shocks of May 1990. The devastating 1977 magnitude 7.4 earthquake, which killed roughly 1,500 people in Bucharest, was recorded within Romania at a single station. Attempting statistically robust source and path analyses with such a sparse database of major events is a formidable challenge, and one reason Vrancea has been left out of global ground-motion studies for decades.

The new framework tackles this problem head-on with a series of methodological innovations. First, rather than letting the recordings themselves define the grouping of data, the researchers built a zonation of the affected region from independent geological, tectonic, geophysical and geomorphological evidence, together with maps of the fundamental resonance frequency of near-surface sediments. This produced eight zones, from the Dobrogea Platform with its shallow ancient bedrock, through the deeply sedimented Dacian Basin accumulation zone, to the Focsani Basin with its exceptional sediment thickness and strong local topographic effects. Because the zoning is defined without reference to strong-motion data, it avoids circular reasoning and serves as an external pivot for organizing the region’s heterogeneity.

A preliminary spectral comparison across these zones immediately revealed systematic differences. The Dobrogea region showed a narrow amplification band peaking near 0.1 seconds, matching its independently mapped resonance frequency, while for larger earthquakes the Focsani Basin and the southern Moesia accumulation zone displayed pronounced amplification in the 0.5 to 2.5 second range. Critically, the two accumulation zones behaved similarly for moderate earthquakes but diverged sharply for large ones, suggesting that bigger ruptures activate deeper sedimentary packages. This supports what the authors call a dynamic boundary between path-controlled and site-controlled behavior, rather than a fixed depth dividing local site conditions from the deeper propagation medium.

The framework then performs what the team calls a uniformization of site effects. Because moderate-magnitude and large-magnitude datasets exhibit different site responses, an average ratio between their amplification patterns was computed and applied to the large-event data, bringing both datasets to a common reference site condition. This allowed the sparse large-event recordings and the more numerous moderate events to be combined into a single database for estimating path parameters. Stress drop was deliberately fixed at a physically plausible 100 bar and never used as a fitting parameter, a choice designed to avoid the source-site trade-offs that have plagued earlier work. Strikingly, when the analysis was repeated with stress-drop values ranging from 50 to 300 bar, the derived attenuation parameters did not change at all; the variations were absorbed entirely by site amplification, revealing the hidden coupling that had made earlier stress-drop estimates so unstable.

The results are internally consistent and, crucially, unremarkable. Geometrical spreading follows the physically expected inverse-distance decay for body waves, which dominate intermediate-depth ground motions. Frequency-dependent anelastic attenuation was determined independently for each zone, with coefficients of determination exceeding 85 percent for most zones and reaching about 98 percent in the best-constrained one. The zone-to-zone differences in attenuation, lowest over the North Moesia ridge and strongest around the Focsani Basin and Transylvanian side, directly explain why previous non-zonated studies produced such wildly different attenuation functions: they were averaging over irreducibly heterogeneous propagation paths. Site amplification envelopes derived for each zone are physically plausible and match independent stratigraphic evidence, with the deep basins amplifying long-period motion and the shallow-bedrock zones concentrating their response at short periods.

The implications extend well beyond Romania. Vrancea belongs to a very small global class of highly active intermediate-depth seismic nests, alongside Bucaramanga in Colombia and the Hindu Kush in Afghanistan, and its earthquakes shape seismic design requirements across more than two-thirds of Romanian territory. The long-period amplification characteristic of Vrancea ground motions is already embedded in the Romanian design code through spectral corner periods of 0.7, 1.0 and 1.6 seconds, far longer than the 0.3 to 0.5 second bands typical elsewhere, pushing the most severe seismic demand from low-rise buildings toward mid- and high-rise structures. The new framework, the authors argue, is transferable to any tectonic setting characterized by sparse strong-motion data and non-standard ground motions, provided sufficient independent geological and geophysical information exists to structure the regional heterogeneity. The broader lesson is perhaps the most satisfying one in science: what looks like an exception to the rules may simply be a complicated case in which the rules have not yet been applied coherently. Vrancea, it turns out, was never breaking the laws of seismology. It was just hiding them behind layers of complexity that no one had thought to peel apart.

Subject of Research: Seismic complexity and ground-motion characterization of the Vrancea intermediate-depth seismic source in Romania

Article Title: Defining and resolving seismic complexity through a unified source–path–site framework: the Vrancea intermediate-depth ground motions

Article References: Cotovanu, A., Cojan, E., & Vacareanu, R. (2026). Defining and resolving seismic complexity through a unified source–path–site framework: the Vrancea intermediate-depth ground motions. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02713-4

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02713-4

Keywords: Vrancea, intermediate-depth earthquakes, seismic hazard, stress drop, anelastic attenuation, geometrical spreading, site amplification, ground motion prediction, Romania, Carpathians, sedimentary basins, seismology

The problem hinges on a temperature window that thermochronologists call the partial retention zone. In the zircon (U-Th)/He system, this is the range of temperatures, roughly between about 130 and 200 degrees Celsius depending on grain properties, within which radiogenic helium leaks out slowly rather than being fully retained or fully lost. A sedimentary sample that never entered this window after deposition is unreset: its single-grain helium ages all predate deposition and speak purely of source-region cooling. A sample heated well above the window is fully reset: its ages all postdate deposition and record cooling in the basin. But a partially reset sample, heated into the window, produces a spread of ages straddling the depositional age, a mixture of each grain’s individual pre-depositional history and the shared post-depositional one.

That mixture is precisely why partially reset samples have long been treated as a nuisance rather than a resource. In theory they are the most informative samples of all, because merely knowing that a sample spent time in the partial retention zone pins down the timing and temperature of maximum burial heating far more tightly than the loose upper or lower limits offered by unreset or fully reset samples. Correcting the measured ages for post-depositional helium loss would also recover when each grain’s source rock cooled, information that fully reset samples destroy entirely. The obstacle has always been that standard inverse thermal-history modeling, started at the depositional age, produces systematic biases: it underestimates burial temperature when many ages predate deposition, and overestimates it toward a full-reset scenario when most ages postdate deposition.

Earlier approaches tried to break the deadlock by combining two dating methods on the same grains. In the popular zircon U/Pb–(U-Th)/He double-dating scheme, the U/Pb age marks each grain’s crystallization, the high-temperature starting point of its thermal history, while the helium age records how much of the accumulated helium survived. Reiners and colleagues in 2005 devised a first-order correction based on the grain with the smallest total helium loss, and Fosdick and colleagues in 2015 introduced forward modeling of combined pre- and post-depositional paths evaluated with a Kolmogorov-Smirnov test. Both, however, rest on assumptions about the pre-depositional history, such as rapid post-crystallization cooling near the surface, that are often unknowable, especially for ancient sediments whose source rocks have long since eroded away.

The Calgary team’s innovation is elegant in its simplicity: stop assuming anything about the pre-depositional past, and instead exploit the few grains that record only the shared post-depositional story. These are syn-depositional grains, volcanic or shallow magmatic zircons that crystallized at or very near the time the sediment was laid down. Because they had almost no time to accumulate and lose helium before burial, their helium ages reflect essentially nothing but the basin’s thermal history. The researchers use inverse temperature-time modeling of these grains, performed in the widely used software HeFTy, to generate a large set of candidate post-depositional temperature-time paths.

Each candidate path is then put on trial. The team forward-models the post-depositional history to determine how much helium accumulated after deposition and what fraction of the pre-depositional helium survived. From the measured helium concentration they back-calculate a pre-depositional model age for every grain under that path, using a generic age equation that accounts for the decay of uranium and thorium through geologic time. The crucial test is a likelihood criterion: a plausible path must yield pre-depositional model ages that fall between each grain’s U/Pb crystallization age and the depositional age, because cooling through the partial retention zone in the source region can only have happened after the grain formed and before it was deposited. A Monte Carlo procedure incorporating the uncertainties on all three ages assigns a probability to every path, and a knee-detection algorithm selects the subset of highest-likelihood histories whose fits remain distinguishable from one another.

On synthetic data with known thermal histories, the method performs impressively. Where the classic correction of Reiners and colleagues pushed six of ten grains more than ten million years away from their true pre-depositional ages, the new strategy recovered maximum burial temperatures of 160 to 190 degrees Celsius at 25 to 20 million years ago, close to the true value of 168 degrees, and matched nearly all true pre-depositional ages within ten million years. Unlike the Fosdick approach, which evaluates the bulk sample and can overlook minor sources with distinct cooling histories, the new method delivers pre-depositional ages grain by grain, allowing the same kind of provenance interpretation applied to unreset samples, from clusters of grains that crystallized and cooled together to recycled grains from fully reset metamorphic sources.

To demonstrate the approach on real rocks, the team applied it to a Devonian sandstone from the Imperial Formation in the Mackenzie Plain of the Northern Canadian Cordillera, part of the vast Ellesmerian clastic wedge shed from terranes that collided with Laurentia in the Late Devonian to Mississippian. The zircon grains yielded U/Pb ages ranging from 364 million years to 2.9 billion years, while their helium ages spanned 57 million to 2.03 billion years, straddling the depositional age of about 364 million years, with roughly 73 percent of grains postdating deposition. That pattern confirmed a high degree of partial reset. Three young, near-syn-depositional grains with concordant U/Pb ages below 400 million years anchored the inverse modeling, and the knee-detection algorithm distilled six best-fitting thermal histories from 250 candidate paths.

The results were validated against an independent, higher-temperature chronometer measured on the very same grains: zircon Raman dating, which tracks radiation damage in the crystal lattice rather than helium. The pre-depositional Raman model ages preserved a bimodal distribution, separating Paleo- to Mesoproterozoic cooling of the Canadian Shield from Neoproterozoic to Paleozoic cooling in younger source terranes, and for one Raman band every single model age fell within the expected envelope. The modeled burial histories also agreed broadly with existing thermal models of the Imperial Formation built from apatite fission-track and helium data, pointing to Late Cretaceous to Paleogene heating at peak temperatures of roughly 100 to 160 degrees Celsius between 90 and 70 million years ago, and matching detrital muscovite argon-argon ages from the same formation.

The authors are candid about the method’s Achilles heel: it needs syn-depositional grains, ideally three to ten of them, which are plentiful in strata fed by active magmatic arcs but scarce in sediments derived from ancient cratons. They suggest screening strategies, laser-ablation double dating that can process dozens to hundreds of grains without bias, and fallbacks ranging from clast-based analysis to fully reset low-temperature thermochronometers. Near-fully reset samples also weaken the likelihood criterion, and simplifications such as uniform uranium-thorium zoning or an alpha-ejection-shaped initial helium profile can be refined in future work. Yet the payoff is a fundamental shift in perspective: rather than avoiding partially reset samples, geologists can now target them, extracting both the depth and timing of basin burial and the low-temperature cooling of vanished mountain belts from a single handful of sand. To spread the technique, the team released PaRACAS, an open-source Jupyter notebook that calculates, plots, and evaluates pre-depositional model ages from HeFTy output, and the same logic extends naturally to apatite U/Pb with helium or fission-track dating, promising a broader toolkit for reading Earth’s thermal memory.

Subject of Research: A new thermochronological modeling strategy for disentangling pre- and post-depositional thermal histories in partially reset detrital zircon samples

Article Title: Technical note: Disentangling pre- and post-depositional thermal histories in partially reset samples

Article References: Härtel, B. P., Enkelmann, E., & Maitra, A. (2026). Technical note: Disentangling pre- and post-depositional thermal histories in partially reset samples. Geochronology, 8(3), 475-494. https://doi.org/10.5194/gchron-8-475-2026

Image Credits: AI Generated

DOI: 10.5194/gchron-8-475-2026

Keywords: thermochronology, zircon, U-Pb dating, helium dating, partial reset, sedimentary basins, thermal history modeling, detrital grains, Canadian Cordillera, geochronology, burial heating, provenance

The research, led by Samuel O. Sedara of the CSIR-National Geophysical Research Institute in Hyderabad and Adekunle Ajasin University in Nigeria, together with colleagues from Nigerian institutions, integrated an unusually broad set of data. The team compiled 175 heat-flow and geothermal gradient records alongside 1,300 radiometric measurements of the three heat-producing isotopes: uranium-238, potassium-40 and thorium-232. These measurements were organized across six geomorphic regions of the country, covering the northwest, northeast, north-central, southeast, south-south and southwest zones, allowing the authors to compare thermal behavior between Nigeria’s ancient crystalline basement complexes and its younger sedimentary basins for the first time in a single analytical framework.

What makes the study methodologically distinctive is its reliance on an independent multi-criteria decision analysis, or MCDA, framework designed to strip subjectivity out of geothermal favorability mapping. Rather than assigning weights to different geophysical parameters by expert judgment alone, the researchers derived weights objectively using Shannon entropy, a statistical measure of the information content of each variable, and cross-checked them with the analytic hierarchy process, which achieved a consistency ratio of just 0.003, far below the 0.10 threshold generally accepted as reliable. From this foundation the team constructed three composite indices: a thermal index, a heat-flow-weighted index, and a three-parameter geothermal favorability threshold index, each designed to explicitly separate conductive heat flow, the heat arriving from deeper sources, from radiogenic heat flow generated within the crust itself.

That separation is the analytical heart of the paper. Continental heat flow has two principal contributors: the slow decay of uranium, thorium and potassium in crustal rocks, and heat conducted upward from the mantle and lower lithosphere. By computing the ratio of conductive to radiogenic heat flow for each region, the authors could ask a deceptively simple question: is a region hot because its rocks are radioactive, or because something beneath the crust is supplying additional heat? In the northwest, the answer was unambiguous. The region recorded the dataset’s highest conductive heat flow at 151.4 milliwatts per square meter and a geothermal gradient of 56.0 degrees Celsius per kilometer, and its conductive-to-radiogenic ratio of roughly 86 means that 98.8 percent of the surface heat flow cannot be attributed to crustal radioactivity.

The implications of that number are profound. A purely radiogenic explanation for the northwest’s thermal anomaly is inconsistent with the data, the authors conclude, and a deeper heat source is required. While surface measurements and Curie point depth estimates, which track the depth at which magnetic minerals lose their magnetization and provide an independent proxy for crustal temperature, cannot distinguish among mantle upwelling, lithospheric thinning, or deep tectonic reactivation as the specific mechanism, the decoupling between conductive and radiogenic heat is real and quantified. This is, according to the study, the primary geoscientific result: Nigeria’s northwest is not merely warm, it is anomalously hot for reasons rooted in the deep Earth, placing it in a geodynamic category that few expected for a region far from active plate boundaries.

Crucially, the finding does not rest on a single line of evidence. The researchers subjected their rankings to a battery of independent validations. Bootstrap resampling with 1,000 iterations tested the stability of the favorability class boundaries at plus or minus 0.50 standard deviations. A random forest regression model, a machine learning algorithm that builds predictions from many decision trees, achieved a coefficient of determination of 0.702, a moderate but respectable performance given the small regional sample. K-means unsupervised clustering, which groups regions by similarity without reference to the MCDA labels, produced a silhouette score of 0.397 and an adjusted Rand index of 0.074, modest values the authors attribute candidly to the limited number of data points, since with only six regions even a single misclassification sharply depresses the agreement metric. The team is explicit that these machine learning results should be read as supporting evidence within the overall multi-method framework rather than as standalone proof.

The convergence, however, is what gives the northwest result its weight. Curie point depth-derived heat flow, random forest regression, bootstrap validation and prior independent studies all point to the same region. Across every composite index, the northwest ranks first, with a thermal index of plus 1.715, a heat-flow-weighted index of plus 1.864 and a geothermal favorability threshold index of plus 1.343. The Sokoto Basin, which spans Sokoto, Kebbi and Zamfara states, together with nearby northwest sedimentary terrains, is continuously identified as the most attractive exploration target in the country. The authors recommend urgent geophysical investigation of the basin and slim-hole drilling, along with a dedicated thermal model to establish actual temperature-at-depth profiles before any full exploration campaign begins.

The study also redraws the map of geothermal opportunity in a second, very different way. The southeast region, with a thermal index of plus 0.490, represents not a secondary version of the northwest prospect but an entirely distinct type of geothermal target. Its thermal regime is radiogenically sourced and dominated by potassium-40, meaning its heat comes from the decay of radioactive elements within crustal rocks rather than from below. That character makes the southeast better suited to direct-use applications, such as district heating, agricultural drying and greenhouse warming, than to power generation, and the authors caution that it cannot be directly compared with the northwest. The north-central and northeast regions emerge as moderately favorable, while the south-south and southwest rank as unfavorable in this screening.

The authors are careful to frame the scope of their conclusions. This was a regional-scale screening exercise, and it did not address the factors that ultimately determine whether a geothermal prospect can be developed: permeability, fluid content, reservoir depth, sustainable extraction rates and drilling feasibility. Those questions remain prerequisites for any actual development decision, and no amount of surface and magnetic data can substitute for them. Yet the study transforms the starting point for Nigerian geothermal exploration. By quantifying, for the first time at national scale, where the country’s heat comes from and how strongly each region scores across independently weighted and validated indices, it converts a diffuse sense of possibility into a ranked, evidence-based agenda. If subsequent geophysics and drilling confirm what the numbers suggest, the Sokoto Basin could place Nigeria on the geothermal map, adding a firm, weather-independent renewable resource to an energy economy in urgent need of diversification.

Subject of Research: National-scale geothermal resource assessment of Nigeria using multivariate and machine learning analysis of heat flow and radiometric data

Article Title: A New Multivariate Analysis of Geothermal Assessment of Nigeria’s Crystalline Basement and Sedimentary Basins: Thermal and Geodynamic Implications

Article References: Sedara, S. O., Alabi, O. O., Adekanle, O. J., Adekanye, O. O., & Christopher, O. A. (2026). A New Multivariate Analysis of Geothermal Assessment of Nigeria’s Crystalline Basement and Sedimentary Basins: Thermal and Geodynamic Implications. Natural Resources Research. https://doi.org/10.1007/s11053-026-10773-1

Image Credits: AI Generated

DOI: 10.1007/s11053-026-10773-1

Keywords: geothermal energy, Nigeria, heat flow, radiogenic heat production, Sokoto Basin, multi-criteria decision analysis, random forest, Curie point depth, geothermal gradient, crystalline basement, sedimentary basins, geodynamics