Basin Research - Volume 35, Issue 3, 2023

The southwest depocentre of the Magallanes Basin records the change from a rifting, thermal sag and foreland development since the Middle Jurassic to Neogene, separated by boundaries surfaces and major unconformities. Its internal geometries and stacking patterns respond to variations such as tectonic load and flexural subsidence, accommodation space, sediment supply variation and relative sea‐level fluctuations.

This contribution characterizes primary lithologic and depositional components of the Magallanes‐Austral basin and defines infill geometries and stacking patterns from seismic and well data. An integrated seismic model is proposed for recognition of rifting, thermal sag and foreland tectono‐stratigraphic phases based on depositional geometries and its relation with the evolving deformational and geodynamic framework. Above a Middle–Late Jurassic extensional phase, evidenced by synrift depositional geometries, follow marine successions representing the subsidence thermal sag phase (Tithonian–Early Cretaceous) characterized by concordant and laterally extensive seismic reflectors. The following foreland phase is described through the evolution and lateral migration history of the foredeep depocentre and concomitant forebulge development. The foreland phase is represented by different stages characterized by asymmetric sedimentary wedges bounded by basal surfaces and/or major unconformities recording transitions from underfilled to overfilled conditions. The accumulated thickness due to lithospheric flexure reflects different foreland subsidence profile patterns across the southern depocentre of the Magallanes‐Austral basin, producing asymmetrical westward and southward thickening wedges. The first Foreland I stage (Coniacian?–Maastrichtian) is recorded as an asymmetric wedge infill, that thins cratonward, with a NW‐trending foredeep axis. The erosive basal foreland surface (BF) at its base deepens towards the west and south along the active margin of the basin, where subsidence was maximum. On top of it, along the western portion of the basin and with a source area from the north, deep‐marine slope deposits and turbiditic complexes were deposited; while on the forebulge to the east, a clastic platform developed. The Foreland II stage (early‐to‐middle Palaeocene–middle Eocene) is characterized by renewed uplift and flexure, and increasing tectonic subsidence rates, building a new clastic wedge‐shaped foreland succession next to the orogenic belt, and a well‐represented forebulge to the east. Subsequently, an extensive diachronous G7 unconformity was generated, eroding locally the previous foreland deposits towards the eastern margin. A pronounced and continuous NW‐SE trending deflection is established subtly to the east. The following Foreland III stage (middle to late‐Eocene–Oligocene) is characterized by a reduction in thrust load along the western active margin, and progradational systems towards the NE, a time during which the subsidence rate decreased and accommodation space was reduced. Deposition occurred within a wide and continuous NW‐SE trending foredeep without a marked forebulge. The top of this stage is the A1 unconformity, marking the beginning of the Foreland IV stage (early Miocene–Neogene), regarded as an overfilled basinal stage without a marked foredeep and major variations in thickness across the extent of the basin. The depositional pattern in this stage is largely conformal and tabular. The proposal model represents an evolutionary example for the internal geometry of deep‐marine foreland basin system, including variables such as tectonic load and flexural subsidence, accommodation space, sediment supply variation, and relative sea‐level fluctuations.

Models of the formation of rifted margins have significantly evolved over the last decades by identifying new styles of crustal thinning and magmatic production. However, the expression of these different processes in the depositional environments of the overlying basins remains to be determined. Using only published data, we integrated the sedimentary evolution of 21 basins of the Equatorial, Central and South segments of the South Atlantic that record various styles of crustal thinning and magmatic production. To compare these basins that underwent rifting at different times, we developed a new type of analysis allowing to evaluate statistically the (dis)similarities in depositional environment trends by normalizing them to the tectonic phases of the basin (syn‐rift, transition and post‐rift) rather than the stratigraphic or absolute ages: The GeoDyNamical Analysis. We show that the timing of the long‐term retrograding mega‐sequence driven by lithosphere thinning depends on the deformation style and magma production. Along oblique margins of the Equatorial Segment, deepening initiated during syn‐rift because their narrow crustal thinning style favours rapid tectonic subsidence surpassing sediment supply. Along wide margins of the Central Segment, deepening is initiated later, at the end of the transition phase, because depth‐dependent thinning favours slow tectonic subsidence and late break‐up. Along magma‐rich margins of the South Segment, deepening is initiated during the transition phase, after volcanics stopped filling accommodation created by subsidence. In the Central Segment, evaporites accumulated during the second half of the transition phase, when crustal thinning ceased in the proximal margin and migrated to its distal part. Immediately before and during evaporites accumulation, sediments recorded continental and coastal depositional environments resulting from the limited thermal subsidence in the proximal margin domain. Evaporite deposition lasted until the initiation of retrograding mega‐sequence, at the onset of the post‐rift phase and the end of crustal thinning in the distal margin.

We show that the timing of the long‐term retrograding mega‐sequence driven by lithosphere thinning depends on the deformation style and magma production. Along oblique margins of the Equatorial Segment, deepening is initiated during syn‐rift because their narrow crustal thinning style favours rapid tectonic subsidence surpassing sediment supply. Along wide margins of the Central Segment, deepening is initiated at the end of the transition phase because of depth‐dependent thinning favours slow tectonic subsidence and late break‐up. Along magma‐rich margins of the South Segment, deepening is initiated during the transition phase, after volcanics stopped filling accommodation created by subsidence.

The Taiwan Western Foreland Basin is thought to have received sediment mainly from Eurasia until the late Pliocene–early Pleistocene. However, clay mineralogy, δ¹³Corg and C/N of organic matter and magnetic susceptibility of the Kueichulin Formation show the rapidly uplifting Taiwan became the dominant sediment source at the Miocene–Pliocene transition.

The Taiwan Western Foreland Basin is thought traditionally to have received sediment mainly from Eurasia until the late Pliocene–early Pleistocene, after which time, the Taiwan orogen became the dominant source. However, a combination of clay mineralogy, δ¹³Corg and C/N of organic matter, and mass‐specific magnetic susceptibility of late Miocene to early Pliocene strata of the Kueichulin Formation indicate that onset of major sediment contributions from Taiwan occurred much earlier, and correlates closely to the uplift and initial emergence of the Taiwan orogen. Clay mineralogy shows an upsection increase in illite and illite crystallinity, and a decrease in chlorite and kaolinite after the late Miocene, and this is attributed to rapid erosion of the Taiwan orogen. Results from δ¹³Corg and C/N analyses show that organic material in the Kueichulin Formation changed from dominantly marine to dominantly terrestrial in the early Pliocene, and this is linked to the delivery of large quantities of terrestrial organic material from the Taiwan orogen to the adjacent Taiwan Strait. Magnetic susceptibility also decreases significantly during the early Pliocene, resulting from dilution of magnetic minerals through the influx of non‐magnetic minerals delivered from the Taiwan orogenic belt. The establishment of the growing Taiwan orogen as a major sediment source to the Western Foreland Basin occurred at the Miocene–Pliocene transition, about two million years earlier than previously recognized.

Cretaceous‐Miocene sedimentary rocks in the Nepalese Lesser Himalaya provide an opportunity to decipher the timing of India‐Asia collision and unroofing history of the Himalayan orogen, which are significant for understanding the growth processes of the Himalayan‐Tibetan orogen. Our new data indicate that detrital zircon ages and whole‐rock Sr‐Nd isotopes in Cretaceous‐Miocene Lesser Himalayan sedimentary rocks underwent two significant changes. First, from the Upper Cretaceous‐Palaeocene Amile Formation to the Eocene Bhainskati Formation, the proportion of late Proterozoic‐early Palaeozoic zircons (quantified by an index of 500–1200 Ma/1600–2800 Ma) increased from nearly 0 to 0.7–1.4, and the percentage of Mesozoic zircons decreased from ca. 14% to 5–12%. The whole‐rock ⁸⁷Sr/⁸⁶Sr and εNd(t = 0) values changed markedly from 0.732139 and −17.2 for the Amile Formation to 0.718106 and −11.4 for the Bhainskati Formation. Second, from the Bhainskati Formation to the lower‐middle Miocene Dumri Formation, the index of 500–1200 Ma/1600–2800 Ma increased to 2.2–3.7 and the percentage of Mesozoic zircons abruptly decreased to nearly 0. The whole‐rock ⁸⁷Sr/⁸⁶Sr and εNd(t = 0) values changed significantly to 0.750124 and −15.8 for the Dumri Formation. The εHf(t) values of Early Cretaceous zircons in the Taltung Formation and Amile Formation plot in the U‐Pb‐εHf(t) field of Indian derivation, whereas εHf(t) values of Triassic‐Palaeocene zircons in the Bhainskati Formation demonstrate the arrival of Asian‐derived detritus in the Himalayan foreland basin in the Eocene based on available datasets. Our data indicate that (1) the timing of terminal India‐Asia collision was no later than the early‐middle Eocene in the central Himalaya, and (2) the Greater Himalaya served as a source for the Himalayan foreland basin by the early Miocene. When coupled with previous Palaeocene‐early Eocene provenance records of the Tethyan Himalaya, our new data challenge dual‐stage India‐Asia collision models, such as the Greater India Basin hypothesis and its variants and the arc–continent collision model.

Simplified palaeogeographic framework of the Himalayan orogen and Indus‐Yarlung suture zone denoting provenance changes in sedimentary rocks in the TH, LH and Sub‐Himalaya and tectonic evolution of the Himalayan orogen from the initial India‐Asia collision to the early‐middle Miocene.

New outcrop, ash‐bed dating and well data have been integrated with recently published seismic data to detail the paleogeographic development of the Early‐Middle Jurassic Cuyo Group margin in southern Neuquen Basin. The topsets partition into sand‐rich subaqueous deltas, a muddy tidal shoreline zone and an inner topset alluvial zone that can be detected on subsurface data.

New Cuyo Group outcrop data complement recently published seismic and well data that detail the progradational character of the Lower‐Middle Jurassic Neuquén Margin (Argentina). The deepwater margin, with shelf topset (Lajas Formation), slope break and deepwater slope to basin‐floor deposits (Los Molles Formation), prograded northward and westward as large‐scale clinoforms (250–500 m high) for 120 km, during 13 My, supplied by sediment mainly from the North Patagonian Massif. The studied Lajas Formation topsets are themselves progradational, with a 500 m‐thick vertical succession of subaqueous delta, shoreface with associated tidal flat, mouth bar, fluvio‐tidal channel and alluvial plain deposits. This pattern is confirmed by facies analysis in five areas of outcrops and well data but is interrupted by frequent marine transgressions that add a short‐term cyclicity to the succession. A new paleogeographic map suggests previous disagreements on process stratigraphy are due to shoreline/paralic strike variability and to increased basinal process impact as the topset/shelf widened. A marked feature of each Lajas topset sequence is a differential partitioning of sand and mud, though not with a simple proximal to distal grain‐size reduction. The sand‐prone outer shelf passes landward to a channelized muddy shoreline environment, and then to a mixed sandy and muddy channelized coastal and alluvial plain. This type of partitioning, important for the characterization and prediction of reservoir quality, can also be recognized on seismic and well log data.

The Middle Jurassic–Early Cretaceous evolution of the Neuquén Basin is traditionally attributed to a long phase of thermal subsidence. However, recent works have challenged this model. In view of this, we study the Late Jurassic Tordillo Formation, a non‐marine depositional unit that marks a shift to regional regression across the basin. Previous studies propose different causes for this regression, including the growth of the magmatic arc in the west, uplift in the south or extension in the north. We studied the Tordillo Formation in sections located at an intermediate position in the Neuquén Basin, in order to understand the tectonic processes active during sedimentation. We present evidence of normal faulting within the Tordillo Formation and the base of the overlying Vaca Muerta Formation. Some of these faults can be attributed as syndepositional. We characterize the Tordillo Formation as part of a distal fan‐playa lake depositional system with a contemporaneous western magmatic arc as the main source of sediment. When compared to the Late Triassic–Early Jurassic NE to NNE‐oriented rifting, which marks the opening of the Neuquén Basin, the Late Jurassic extension shows a switch in stress orientation; the latter is orthogonal to the north‐trending subduction zone. We interpret this change as a renewed phase of back‐arc extension induced by slab rollback along with minor distributed intraplate extension prior to opening of the South Atlantic Ocean.

This study attempts to understand the Late Jurassic evolution of the Neuquén Basin, particularly during Tordillo Formation sedimentation, which has been linked to opposite tectonic scenarios: extension and compression. To achieve this, we performed structural, sedimentological and provenance analyses. We found evidence of syndepositional extension within the Tordillo Formation.

Low‐angle detachments are fundamental crustal structures found in many extensional systems and plate tectonic boundaries, including onshore extensional basins, rifted margins and mid‐oceanic ridges. Direct observations of the complete geometry of extensional detachments are rare so that aspects of our understanding of their development and evolution rely mainly on proxy observations and numerical simulations. A high‐resolution 3D seismic reflection survey Offshore West of Ireland images a complete corrugated extensional detachment, from its steep oceanward breakaway faults to its back‐rotated domal crest. The detachment surface, the P reflector, developed during the Jurassic hyperextension of the Porcupine Basin and is preserved in its slip position. It covers 95 × 35 km area and has a N‐S elongate domal shape, at right angles to the prevailing extension direction, with a crest at ca. 6.3 s two‐way travel time. It is overlain by a syn‐rift sequence offset by steep frontal faults that pass eastward into shallower, predominantly west‐dipping highly listric faults that merge downwards with the detachment. The detachment has pronounced E‐W corrugations parallel to the basin opening direction, and N‐S lineaments that correspond with the footwall cutoff lines of overlying Jurassic faults. The most significant N‐S lineaments correspond with changes in dip of the detachment. We propose that the geometry of P can be explained by a conceptual model in which the detachment was assembled from initially steep faults that developed at the front of P and back‐rotated to form listric faults during extension, with punctuated oceanward propagation of the segments of the detachment. Comparisons with 2D profiles and 3D surfaces of published detachments suggest that our conceptual model may be applicable to other detachments that accommodate extreme extension at other rifted margins and at mid‐oceanic slow and ultra‐slow spreading ridges.

Detachment structure in the Porcupine Basin, West of Ireland. (a) Location, (b) 2D view and (c) 3D view. The Porcupine detachment studied in 3D displays corrugations and faults footwall cutoffs ridges that give insights on the kinematics of its development.

Understanding the source‐to‐sink relationship of a large river‐marginal sea system is key to using marginal sea sediments to infer terrestrial erosion/weathering variations. The Zambezi River, the largest river in the southern African region, has been transporting large amounts of sediments to the southwestern Indian Ocean since the Cretaceous, which have been often used to infer river integration history and uplift of the southern African region. Thus, characterizing the geochemical features of different parts of the river is the key to correctly interpreting terrestrial sediment signals in the southwestern Indian Ocean drill cores. Here we present the first provenance study based on Sr‐Nd‐Hf isotopic results of river sands from mainstream and tributaries of the Zambezi River. We find that the isotopic signatures of the river sediments are largely consistent with its underlying basements of the different reaches, which suggests the local geology control of the river sedimentary provenance. This result is in line with the studies of the provenance of the Yellow and Yangtze Rivers, which suggest that sediments transported by the upper reaches of large rivers draining interior continents are primarily stored in sedimentary basins on land instead of marginal seas. This study suggests caution must be taken in using sediments of marginal seas to infer erosion history of the hinterland mountain uplift and exhumation.

To understand the source‐to‐sink relationship of the Zambezi River‐marginal sea system, we present the first provenance study based on Sr‐Nd‐Hf isotopic results of river sands from mainstream and tributaries of the Zambezi River. We find that the isotopic signatures of the river sediments are largely consistent with its underlying basements of the different reaches, which suggests the local geology control of the river sedimentary provenance.

3D seismic identifications of thin‐skinned deformation above a basal mobile shale, and their implications on platform region of Tarakan Basin.

Deformation on shale‐rich continental margins is commonly associated with thin‐skinned extension above mobile shales. Normal faulting and shale mobilization are widespread on such margins, being associated with and controlled by progradation and gravitational failure of deltaic sedimentary wedges. However, due to uncertainties in seismically imaging mobile shales, our understanding of problems like how base mobile‐shale controls deformation, and the shape, size, and distribution of shale structures remains poorly understood. Here, we use 3D seismic reflection data from the platform region of the Tarakan Basin, offshore eastern Indonesia to investigate the temporal and spatial evolution of thin‐skinned deformation of the Neogene sedimentary section. Our detailed seismic interpretation reveals up to 74 km long, concave‐ and convex‐into‐the‐basin normal faults, dipping both basinward (eastwards) and locally landward (westwards), which detach downwards on a basal mobile shale (Early‐Middle Miocene). The base of the mobile‐shale unit dips gently (<17°) seaward, although older (Eocene‐Early Miocene), rift‐related normal faults originate local structural highs deforming the base of mobile shales. Our isochore (thickness map) analysis shows that supra‐shale normal faulting commenced in the Middle Miocene and was accompanied by the formation of hanging‐wall rollover folds and associated crestal grabens, with the subsequent along‐ and across strike migration of the deformation related to the nucleation, lateral linkage and reactivation of individual fault systems. Updip growth normal faulting was also accompanied by the downslope flow of mobile shale, accompanied by parallel and perpendicular variations of the differential loading in the delta system, and local contraction and mobile‐shale upbuilding, resulting in the growth of large, margin‐parallel shale anticlines further downdip. The growth faults and anticlines are locally overlain by up to 5 km tall mud pipes and volcanoes. We suggest that variations in the rate of sedimentary loading, mobile‐shale flow, fault growth and gravitational failure of the delta system above a seaward‐dipping, but locally rugose base mobile‐shale surface, controlled Neogene deformation in the Tarakan Basin. We also demonstrate how variations in the trend and dip of the base mobile‐shale surface influence the position, timing of formation and evolution of supra‐shale normal faults and their associated depocentres along shale‐rich, deltaic margins.

Hypogene dissolution‐precipitation processes strongly affect the petrophysical properties of carbonate rocks and fluid migration pathways in sedimentary basins. In many deep carbonate reservoirs, hypogene cavernous voids are often associated with silicified horizons. The diagenesis of silica in carbonate sequences is still a poorly‐investigated research topic. Studies exploring the complexity of silica dissolution‐precipitation patterns in hypogene cave analogues are therefore fundamental to unravel the diagenetic and speleogenetic processes that may affect this kind of reservoir. In this work, we investigated an exhumed and silicified Neoproterozoic carbonate sequence in Brazil hosting a 1.4 km‐long cave. Quartz mineralization and silicified textures were analyzed with a multidisciplinary approach combining petrography, fluid inclusion microthermometry, silicon‐oxygen stable isotope analyses and U‐Th‐Pb dating of monazite crystals. We found that an early silicification event caused the replacement of the dolostone layers with micro‐crystalline quartz forming chert nodules. This event was likely associated with mixing fluids (ancient Neoproterozoic seawater and hydrothermal solutions sourced from the underlying Mesoproterozoic basement) at relatively low temperatures (ca. 50–100°C) and shallow depth. After the tectonic deformation produced by the Brasiliano orogeny, silica dissolution was promoted by high temperature and alkaline hydrothermal solutions rising from the quartzite basement along deep‐rooted structures. Hypogene hydrothermal alteration promoted the dissolution of the cherty layers and the precipitation of chalcedony and megaquartz. Homogenization temperatures from primary fluid inclusions in megaquartz cement indicate minimum formation temperatures of 165–210°C. Similar temperature estimates (110–200°C) were obtained from the δ³⁰Si and δ¹⁸O isotope systematics of quartz precipitated from hydrothermal solutions. The dissolved salts in the fluid inclusions were evaluated as NaCl + CaCl2 from microthermometric data combined with cryogenic Raman spectroscopy, corresponding to salinity ranging between 17 and 25 wt.%. No reliable age constraints for hydrothermal silica dissolution‐precipitation phases were obtained from monazite U‐Th‐Pb dating. However, our results, interpreted in the regional context of the São Francisco Craton, suggest that the Cambrian tectono‐thermal events could have been amongst the possible drivers for this hypogene process in the basin.

δ³⁰Si–δ¹⁸O isotopes and fluid inclusion microthermometry were used to get insight into silica dissolution‐precipitation processes in a cave developed within a (silicified) Neoproterozoic carbonate sequence.

The pore pressure distribution in the Taranaki Basin is controlled by a combination of sediment loading, lithofacies variations, fault zone permeability and structural architecture. This work represents an appraisal of the pore pressure distribution across the whole of a multiphase structurally complex basin, and the approach taken provides a framework for better understanding the distribution of pore fluid pressures and pore fluid migration in other sedimentary basins.

Significant variations in pore pressure across the Taranaki Basin, New Zealand, are attributed to changes in lithofacies and structure, usefully illustrated in terms of ten areas that we term geopressure provinces, each displaying individual pore pressure trends. Cretaceous to Early Miocene formations in different parts of the basin can be either normally pressured (near or at hydrostatic) or significantly overpressured (up to 28 MPa) at the same depth. Variations in Eocene–Oligocene facies types and thicknesses both within and between geopressure provinces provide first‐order control on the magnitude, distribution and maintenance of overpressure across the basin. Examples of hydraulic compartmentalisation due to sealing faults and stratigraphic architecture are identified within the basin. Deep pore pressure transitions are sealed by diagenetic, structural or stratigraphic mechanisms in different places and are associated with an increase in mudrock volume (reduced permeability) or gas generation. Thus, pore pressure distribution in the Taranaki Basin is controlled by a combination of sediment loading, lithofacies variations, fault zone permeability and structural architecture. This work represents an appraisal of the pore pressure distribution across the whole of a multiphase structurally complex basin, and the approach taken provides a framework for better understanding the distribution of pore fluid pressures and pore fluid migration in other sedimentary basins.

Understanding the interactions of submarine channels with seafloor deformations is challenging as these channels more often involve a wide variety of responses relying on both autogenic and allogenic factors. The effect of active growing structures on channel pathways is well documented, but the evolution of lateral migration and the internal architectures along the deflected channel bends around ongoing active structures remain poorly constrained. Here, we use 3D seismic interpretation and quantitative geomorphologic methods to examine the channel bend morphology and the kinematics of lateral migration near gravity‐driven tectonic deformation. Using high‐resolution seismic reflection data acquired from the offshore Niger Delta, two‐channel levee systems (Amaku Major System and Amaku Channel Levee System) have been recognized in the seismic survey. Each system consists of three channel complexes, recording five types of deflected channel bends, defined here as: (i) avulsed bend, (ii) confined bend, (iii) chute cut‐off bend, (iv) blocked bend and (v) kinked bend. Geomorphologic parameters including bend sinuosity, bend amplitude, along‐bend length, straight‐bend length, channel depth and width, were considered within the deflected channels. Lateral migration estimators; channel lateral shift (SH), and channel lateral spacing (CS), were assessed throughout the distances of cross‐sectional channel patterns. The lateral migration estimators (SH and CS) were used to estimate the expression of internal architectures and the evolution of lateral migration around seabed deformation at the scale of the channel complex. The results show that the morphology and internal architecture of the deflected bends, although developing in the same structural context, display varied responses to structural deformation. Unlike previously published models of channel‐fold interactions asserting tectonics as the solitary driver, here we demonstrate that the channel deflections around structures are sensitive to the lateral confinement produced by sediment relief of the outer levees, and the autogenic forcing of channel mechanisms. This study provides new insights into the evolution of submarine channels in active tectonic settings, shows detailed mechanisms of channel bends at a small scale and offers a better understanding of the distribution of sediments in the deep sea.

Submaine channel deflections around growing structures reflect several types of channel bends and competing controls on lateral migration, i.e., tectonic push vs. depositional/autogenic forcing

Uplift of the Tian Shan range modified regional climate during Cenozoic aridification in Central Asia. This study presents facies analyses and Neogene oxygen and carbon isotopic records from magnetostratigraphically dated terrestrial sedimentary sections on the southern side of the intermontane Issyk‐Kul basin in the Kyrgyz Tian Shan and ²⁶Al/¹⁰Be isochron burial ages from the southern and eastern sides of the basin. The δ¹⁸O and δ¹³C data show a positive ca. 2‰ shift in values between ca. 8 and 7 Ma and a change from a negative to a positive trend. This change is attributed to the upwind growth of the Kyrgyz, Kungey and Trans Ili (Zaili) ranges, which diverted the westerlies, thereby changing the Issyk‐Kul basin from a windward to a leeward position, enhancing aridification and establishing the modern‐day spring and summer precipitation regime within the basin. Two 4 to 5 Ma ²⁶Al/¹⁰Be isochron burial ages constrain the onset of Sharpyl Dak deposition on the eastern side of the basin; southward paleocurrent directions there suggest the eastward growth of the Kungey range in the Pliocene. Increased subsidence on the southern side of the basin and local tectonically induced river system reorganization led to the commencement of lake formation at ca. 5 Ma, followed by a ca. 2 Ma local depositional hiatus. The transition from sandstones of the Chu sedimentary group to conglomerates of the Sharpyl Dak group, marking a change from fluvial‐alluvial deposits to a proximal alluvial fan, is dated at 2.6–2.8 Ma by ²⁶Al/¹⁰Be isochron burial dating on the southern side of the basin, driven either by tectonics or Northern Hemisphere glaciation. This study concludes that the late Miocene–Pliocene northward growth of Tian Shan significantly altered environmental conditions within the range, preventing the moisture‐bearing westerlies from reaching the intermontane Issyk‐Kul basin and promoting lake formation and expansion.

The late Miocene–Pliocene northward growth of Tian Shan created an orographic barrier that diverted the moisture‐bearing westerlies and enhanced aridification in the Issyk‐Kul basin. Reorganization of the river systems and enhanced subsidence led to the formation of an internally drained lake in Pliocene. The transition from sandstone to conglomerate (Sharpyl Dak group) deposition, linked to a change in climate and/or tectonic activity, occurred diachronously within the basin.

The Tertiary‐Piedmont Basin (NW Italy) is an episutural basin that developed from the late Eocene on the Alps–Apennines tectonic junction. Several coeval geodynamic processes, including the loading and exhumation of the Western Alps, the outward migration of the Apennine accretionary wedge and the opening of the Liguro‐Provençal rift basin, controlled the basin evolution. We integrate fluid‐inclusion microthermometry, low‐temperature thermochronology and burial history with numerical modelling to constrain the palaeo‐geothermal gradients required and evaluate the mechanisms that governed the basin thermal history. Apatite fission‐track and (U‐Th‐Sm)/He analyses of the basal late Eocene turbidites show reset ages of ca. 25 and 20 Ma, respectively, which require temperatures to be >120°C. Homogenization temperatures up to ca. 130°C from fluid inclusion analyses from authigenic minerals confirm the thermochronometric data, supporting a significant post‐depositional heating in the lower sequence of the basin. Stratigraphic reconstructions and decompaction of the basin fill indicate that the maximum burial experienced by the basal strata at 25 Ma is 2.3 ± 0.1 km, which is not sufficient to reset the AFT thermochronometric system when applying a typical geothermal gradient (ca. 20–30°C/km). An elevated geothermal gradient of 45 ± 5°C/km is thus necessary to explain the thermochronometric dates and the elevated thermal signature at shallow depths. 2D numerical simulations indicate that such an elevated palaeo‐geothermal gradient can be best explained by mantle upwelling, consistent with crustal thinning caused by the inception of the Liguro‐Provençal rift basin and related outward migration of the Alpine and Apennine fronts during the Oligocene.

The Tertiary Piedmont Basin (NW Italy) developed on the Alps–Apennines tectonic junction. By the integration of microthermometry, low‐temperature thermochronology and burial history we constrained a paleo‐geothermal gradient of 45 ± 5°C/km. Numerical simulations indicate that the elevated gradient can be best explained by mantle upwelling.