The extent to which continental acidity during the Early Triassic varied with latitude remains insufficiently constrained, despite its relevance for understanding environmental stress and biotic recovery patterns across the Smithian-Spathian boundary (SSB). We examined the abundance, textures and compositions of strontium-rich hydrated aluminium phosphate-sulphate (APS) minerals in 179 continental samples spanning tropical to high paleolatitudes in both hemispheres. APS minerals display broadly comparable early-diagenetic features across sections, indicating formation shortly after deposition under acidic meteoric conditions. Their distribution suggests a latitudinal trend: APS contents commonly exceed 0.1 vol.% in equatorial western peri-Tethyan basins, where faunal and floral records are sparse during the SSB, whereas concentrations decrease towards higher latitudes and are rare beyond similar to 40 degrees in both hemispheres. This pattern does not appear to correlate with lithological or textural variability and may reflect spatial differences in the intensity or duration of acidification linked to Siberian Traps volcanism. Equatorial basins thus likely experienced more prolonged or recurrent acidic episodes, whereas higher-latitude areas may have been subject to comparatively attenuated effects, potentially contributing to earlier ecological recovery. These results provide a useful framework for evaluating continental acidification and its environmental implications during the interval following the end-Permian mass extinction (EPME).

A recent palaeontological and sedimentological prospecting conducted in the Marrakech High Atlas (Morocco) yielded fossils of Permian medusoids at Taddart (lower part of the Cham-el-Houa Siltstone Formation, Tissiyyi Basin). Some specimens show details of the radial canals and the manubrium. Based on comparisons with the European record, the specimens can be safely ascribed to Medusina atava. They correspond to the first Permian freshwater medusoids from Gondwana and provide crucial information for the reconstruction of equatorial ecosystems during the Permian. The specimens were fossilized in open lacustrine deposits, more specifically in high-density turbidite facies. This discovery (1) contrasts markedly with most European palaeontological sites yielding M. atava, where specimens are preserved in proximal lacustrine deposits formed in shallow-water, periodically emerged environments, (2) expands the palaeogeographic distribution of Permian freshwater medusoids beyond the northern hemisphere, into the equatorial zone, and (3) extends the stratigraphic range of the species M. atava from the early to the middle/late Permian.

This study reports new sedimentological, paleontological and geochronological data from the Perdasdefogu Basin, Sardinia, Italy. Sedimentological investigations showed that the basin hosted a permanent lake, initially infilled by epiclastic and volcaniclastic material, then by carbonates, and finally covered by thick felsic volcanic series. Lacustrine sediments yielded various fossils including plant and temnospondyl amphibian remains. Geochronological investigations, performed by U-Pb analyses on zircon, indicate that the Perdasdefogu Basin was being infilled during the early Permian, between 297.9 +/- 0.9/3.1 and 295.7 +/- 0.7/3.0 Ma (without/with systematic uncertainties propagated, respectively), and covered shortly after, at 295.9 +/- 1.1/3.1 Ma, by volcanic series. These age constraints show that the temnospondyls of the Perdasdefogu Basin, located in the southern side of the Variscan belt, were coeval to those of lower Permian basins located in the northern side of the belt. This demonstrates a rather large areal distribution for these fossil amphibians, which encompassed the northern, inner and southern parts of the Variscan belt. This in turn implies probable hydrographic connections that allowed for vertebrate migration between basins located across the belt. While hydrographic networks represent an obvious dispersal mechanism for ichthyofaunas, geochronological and paleontological data from the Perdasdefogu Basin suggest that this dispersal mechanism also holds for tetrapods, at least for aquatic and semi-aquatic groups. The reorganization of hydrographic networks due to the combined effects of climate change and Variscan tectonics could then have represented a driving mechanism for the migration of tetrapods in central Pangea during the late Carboniferous and early Permian.

The Khorat Plateau, situated in northeastern Thailand and extending partially into Laos and Cambodia, was a thriving ecosystem during the Early Cretaceous. It harboured a diverse array of vertebrate fauna, including freshwater hybodont shark-like fish, actinopterygian fishes, turtles, crocodilians, theropod and sauropod dinosaurs, as well as bivalves. However, not many studies were focused on the flora of this ecosystem. This study focuses on palynological findings from the Sao Khua Formation in the southeastern Khorat Plateau. A total of 74 species from 43 genera were identified, forming an assemblage characterised by Punctatisporites-Dicheiropollis-Classopollis. Based on recent radiometric dating of detrital zircon grains, the Sao Khua Formation is as assigned to an age no younger than the mid to late Valanginian. As the result, the key taxa found in this formation have been calibrated and the age of the palynological assemblage is therefore Valanginian. The assemblage was dominated by pollen of Cheirolepidiaceae together with diversity of pteridophyte spores, suggesting a humid subtropical climate with periodic arid seasons. Comparative analysis with other palynological provinces places this area within the Eastern Tethys Province of the Pan-Tethys Realm.

We report here on a palynoflora from the Spearfish Formation of South Dakota that represents the first definite record of late Permian plant remains in the form of miospores from North America. The assemblage is dominated by taeniate pollen (Lueckisporites virkkiae, Lunatisporites noviaulensis, Corisaccites alutas, Jugasporites spp.) as well as simple saccate pollen taxa (Klausipollenites schaubergeri, Falcisporites spp.), but is highly depauperate in spores. The palynoflora was extracted from a mudstone associated with black fissile shales and carbonates about 30 m above the conformable contact with the underlying Minnekhata Limestone at Cascade Springs. Multiple lines of evidence from organic and carbonate petrology as well as acritarchs indicate that the depositional context was a brackish lagoon or inlet subject to high evaporation rates. Eolian dust, present in all studied units, combined with carbonate and organic petrography, indicates aridity through this interval. Through similarity and ordination analysis, we show that the Spearfish assemblage most closely resembles low paleolatitude palynofloras of late Permian (Lopingian) age in Europe and differs significantly from middle Permian palynofloras of the central United States. The palynoflora also differs from lower Triassic palynofloras, thereby establishing that the lower portion of the Spearfish Formation is late Permian. The similarity in composition of the Spearfish assemblage in the western United States to xeric European assemblages indicates that a near-uniform xerophytic flora dominated by voltzian conifers and peltasperms extended thousands of kilometers across low-latitude Pangaea in late Permian times.

In hydrogeology, a key challenge involves identifying patterns within ancient formations to forecast the distribution of fluid pathways and barriers to permeability, as well as comprehending the palaeohydrological system and its changes over time. This study addresses two main research inquiries concerning fluid flow: firstly, the influence of dolomitization induced by paleosols on flow characteristics, and secondly, the implications for fluid flow pattern distribution in continental sedimentary units. The objectives are pursued through: (1) meticulous, high-resolution measurements of porosity and permeability coupled with well-log data from an outcrop and two boreholes; (2) investigation of petrographic features of diagenetic minerals and their ages using the UPb geochronology system; and (3) an integration of these methodologies to grasp rock properties and fluid flow at a broader scale. Findings suggest that early dolomitization in continental sequences significantly affects fluid flow properties across the basin. The development of paleosols triggered early dolomitization, supported by UPb geochronology evidence. Subsequent groundwater migration along hydraulic gradients, influenced by fluctuations in the local aquifer's water table, facilitated the vertical distribution of dolomitization. Dolomitization occurred in residual pores resulting from initial mineral alteration, early lithifying the sediment and preventing mechanical compaction, thus preserving porosity. During migration events, fluids moved vertically along local faults and horizontally through the dolomitized layers of the formation, which likely remained porous at the time, leading to substantial silica mineralization.

Volcanism from large igneous provinces leads to increases in the Earth’s surface temperature and acidity, thus triggering mass extinction events. However, the dependence of acidity on latitudinal position has remained underexplored and is key to better understand, and react to, global environmental changes today. Here, we study biotic recovery after the catastrophic end-Permian mass extinction, in Early Triassic continental environments. We quantify strontium-rich hydrated aluminum phosphate-sulfate minerals in 179 samples from tropical to circumpolar paleolatitudes in both hemispheres. We provide evidence that latitude controls acidity and its impact on biotic recovery. Subequatorial latitudes concentrate volcanic aerosols through wind circulation patterns, enhancing the impact of acidity on the environment. In contrast, high latitudes provide refuge against environmental change, hosting accelerated recovery after the end-Permian biotic crisis.

Palaeontological prospecting organized in the Ourika and Yagour basins (Marrakech High Atlas, Morocco) in the 1980's, have yielded abundant and exquisitely preserved tetrapod tracks, some of them preserving thinly detailed skin traces (Collection Biron, Cadi Ayyad University, Marrakech, Morocco). Based on this material, diverse morphologies of tracks were described and six new ichnotaxa were erected. However, these trackways have never been reinvestigated in detail from an ichnotaxonomic point of view. Here, the Biron collection is reevaluated using modern photogrammetric imaging techniques. The fine-grained sandstone slabs bear trackways ascribed to Apatopus lineatus, Isochirotherium isp. and Rhynchosauroides isp. whose trackmakers are possible phytosaurs, crocodylian-stem archosaurs or non-crown-group archosauriforms and lepidosauromorphs/archosauromorphs, respectively. "Chirotherium atlensis", "Enigmatopus atlensis", "Hyloidichnus triasicus", "Prochirotherium triasicum", "Pseudochirotherium oukaimedensis" and "Rectilinetopus ourikensis" are considered as invalid. The palaeoichnological assemblage includes a mixture of Early to the Middle Triassic (Isochirotherium) and Late Triassic (Apatopus lineatus) tracks. This result corroborates the biostratigraphic data recently obtain from the base of the Oukakmeden Sandstone Formation, suggesting a Middle-Late Triassic age. The living environment was a semi-arid alluvial plain with ponds and ephemeral rivers.

This study characterizes the depositional environment and climate evolution from the late Permian to the early Middle Triassic, based on detailed sedimentological and palaeosol analysis. Sequence stratigraphy and palae-oenvironmental reconstructions were used to define the Permian-Triassic (P-T) evolution of the High Atlas basins as well as to make a comparison with European basins. The late Permian in Morocco is dominated by distal fluvial fan environment, under arid to semi-arid paleo-climate conditions. Above the P-T unconformity (BS1), the Lower Triassic deposits, record a similar climate evolution from arid to subhumid conditions. In the Argana Basin, the Early Triassic starts by an aeolian deflation lag, followed by stacked debris flow lobes and sheetflood ephemeral alluvial fan deposits, showing immature to locally mature calcretes. The Marrakech High Atlas basins are further characterized by well-developed aeolian dunes in alluvial fan environment. These arid environments evolve through time from proximal to distal deposits, as a retrogradational trend, until well-developed floodplain or lacustrine deposits under semi-arid to subhumid climate (maximum flooding surface, MFS). From MFS, the evolution from distal to proximal environments, testified the progradational trend which is capped by a newly defined angular unconformity (BS2). Above this tectonically induced BS2, the sedimentary section, dated as Anisian is characterized by palaeoenvironments that include meandering river fluvial packages deposited in a semi-arid floodplain. Basin configuration, border fault direction, palaeoenvironments and palaeocurrents recorded in the Argana Basin confirm an independent system, separate from the Marrakech High Atlas (MHA) area during the Triassic. Above BS1, remnant topographies resulted in discrete catchment and discrete drainage systems are evidenced by palaeocurrent and palaeowind measurements controlled by border faults. Palaeoenvironment reconstructions show that the MHA was made up of numerous independent basins during the Early Triassic and the remnant topographies are progressively infilled until BS2. After the BS2, the palaeo-drainage became axial and basins were probably connected in the MHA. Above the P-T unconformity, a common climate evolution is observed in Morocco during the Lower Triassic until BS2, which could correspond to the European Hardegsen unconformity. The sedimentation record shows a similar change in climate and geodynamics to that recorded from both Europe and Morocco.

The Permian marks the transition between the end of the accretion of the supercontinent Pangea and the beginning of its dislocation. In the Eastern Pangea intertropical domain (i.e. the present-day Western Europe), the late-Paleozoic (i.e. uppermost Carboniferous-Permian) history remains poorly constrained due to the lack of precise radiometric data. This is particularly true for Permian basins from the southern part of the French Massif Central, making it difficult to determine correlations between basins and therefore robust timings and constraints on the environmental and climate events described in these basins, and to compare them with the larger-scale settings. This article focuses on the Saint-Affrique Basin, via an integrated petrological, geochemical and geochronological study of eight of the volcanic-ash levels interbedded in the sedimentary succession. It highlights the existence of two different groups of felsic volcaniclastic rocks. The first group, located at the base of the basin and attributed to the Stephanian continental stage, is related to a late-orogenic volcanic setting and corresponds to calc-alkaline trachy-andesitic tuffites that could not be dated due to the lack of volcanic zircon. The second group, located towards the top of the succession, is composed of calc-alkaline dacitic ash beds and tuffites yielding Kungurian ages, i.e. late early Permian (Cisuralian, 283.5 +/- 0.6 to 273.01 +/- 0.14 Ma), and are attributed to a post-orogenic deposition setting. These ages show that the sedimentary filling of the basin is younger than hitherto expected (i.e. Artinskian, 290.1 +/- 0.26 to 283.5 +/- 0.6 Ma). The elemental geochemistry, the presence of inherited detrital zircons and the Hf signatures of the volcanic ones indicate the involvement of an old (Proterozoic and older) basement in the magma genesis; this crustal contribution becomes more prominent towards the top of the sedimentary succession.

Intramontane late Carboniferous–Permian basins of western Europe developed during the latest orogenic stages of the Variscan Mountain Belt in eastern Pangaea, at equatorial palaeolatitudes. Their stratigraphic framework is mainly based on continental subdivisions (e.g. Stephanian and Autunian continental stages), which can be contentious owing to biostratigraphic biases, resulting in long-distance diachronous subdivisions. To provide precise inter-basinal and global correlations to the internationally recognized chronostratigraphic marine stages, this study reports new U–Pb geochronology from the Aumance and Decize–La Machine basins, located in the northern French Massif Central. Zircon grains extracted from three volcanic ash-fall layers give weighted mean 206 Pb/ 238 U ages of 299.11 ± 0.35, 298.73 ± 0.36 and 298.59 ± 0.35 Ma (2 σ total propagated uncertainty) by the chemical abrasion isotope dilution thermal ionization mass spectrometry method, coinciding with the Carboniferous–Permian transition (Gzhelian and Asselian stages). These ages imply that the northern Massif Central basins developed synchronously in relatively short periods of time (<10 myr), reflecting substantial sedimentation rates. Finally, the new chronology of infilling of these basins confirms that they were connected during the late Carboniferous and early Permian periods, improving the knowledge on the late orogenic Variscan geodynamic setting in this area. Supplementary material: Operating conditions and complete analytical results are available at https://doi.org/10.6084/m9.figshare.c.6805228

Abstract The Rochechouart impact structure, located in the western part of the Massif Central in France, has been suggested to be one of the largest impact structures in western Europe. Various age datings have placed the event in a span from the Late Triassic to the Early Jurassic, but the most recent works favour a Late Triassic age. Very little is known about the target environment at the time and location of the impact event. Seemingly coeval, potential tsunamites along palaeoshorelines of the sea that covered parts of continental Europe at the time have been suggested to be related to the impact event and may indicate a marine target setting. Here we apply the method of visual line-logging of the graded suevite in the Chassenon SC2 drill core. This method has previously been used to investigate the depositional environment of similar deposits in several marine target impact craters. It allowed us to compare the deposits at these craters with those at Rochechouart, and in this way not only confirm the marine target setting, but also estimate the target water depth to be ∼200 m. Altogether, our results indicate a palaeogeographic target setting in a newly opened seaway connecting the Paris Basin with the Aquitaine Basin, which may indicate an age of impact at the younger end of the hitherto suggested age-span, i.e. in the late Rhaetian – Early Jurassic.

The evolution of depositional environments in the Late Pennsylvanian-early Permian of the Paradox Basin in Utah, USA, is investigated through detailed sedimentological and high-resolution sequence stratigraphic analyses, in order to define a model of landscape evolution, to discuss the stratigraphic model, and to evaluate the significance of the cyclicity in the paleoclimatic context. Forty high-resolution cycles integrated in 15 minor and two major cycles are observed for the first time throughout the Late Pennsylvanian-early Permian units. A-three steps landscape evolution is recognized. First, the lower Cutler beds, mainly corresponded to a marine environment, with longshore bar, subtidal, tidal, mouth-bar, and with locally fluvial deposits. The upper part of the lower Cutler beds also contains an aeolian dune. Second, the Cedar Mesa Sandstone, corresponded to broad erg deposits which are present across the entire study area, whereas longshore bar, subtidal, mouth-bar, and some fluvial deposits are mainly preserved in the northern part of the studied area. Third, the Organ Rock Formation records decreasing aeolian dune field preservation. To the south, the aeolian environments are interbedded with shoreface deposits, whereas to the north, fluvial deposits with some mouth-bars are more developed. Semi-arid climatic conditions persisted, as indicated by the presence of calcretes. Everywhere in these three steps, root traces within sandstone bars indicate that a soil was once present above the sand dunes. This new model of landscape evolution documents complex interactions between aeolian, fluvial and marine environments within the entire Permian succession of the Paradox Basin. High-resolution stratigraphic analyses allow to discuss the significance of the cyclicity in a scenario that take into consideration sea-level variation in the Late Paleozoic Ice Age paleoclimatic context. This Late Pennsylvanian to early Permian succession reflects both relative sea-level fluctuations and the variability of sediment supply. (c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The reinterpretation of deep wells and the reprocessing and interpretation of 115 km of industrial seismic lines can be used to update the geometry, depositional environments and tectonic evolution of the Carboniferous-Permian Brecy depocenter (southwest Paris Basin). The presentday geometry of the Brecy depocenter is controlled by several eastward dipping normal faults, some of which possibly connected to deep detachments that were active during the late Carboniferous-Permian history. It is estimated that the maximum thickness of the Brecy depocenter is 3900 m. The filling provides evidence for a thick late Carboniferous-lower Permian syn-rift stage overlain by a thin post-rift stage, probably similar to the tectonic evolution of the northeastward basins in the Lorraine region of France and Germany and thus attributed to the lower-middle Permian. The facies generally characterize lake environments, with occurrences of sediment supply attributed to fluvial, alluvial fan and delta fan deposits. They mainly display a retrogradational-progradational pattern during the synrift stage, and a retrogradational pattern during the post-rift stage. The Brecy area was part of a larger late Variscan basin during the latest Carboniferous-early Permian times in the northernMassif Central region.

We report on a multi-proxy study of the Carnian Pluvial Episode in the continental Argana Basin (Morocco) based on mineralogy, geochemistry, paleosols and sedimentary features. The study focus on two sections of the Irohalene Member (unit t5) of the Timezgadiouine Formation dated as late Julian-early Tuvalian through clam shrimp (conchostracan) associations. The sedimentary study of the Irohalene Member defines three parts: lower, middle and upper (t5.1, t5.2, t5.3 respectively). The base of the lower part comprises channels with gravel and sandy bars related to proximal areas, and fluvial meandering systems, overbank and floodplain deposits developing upwards. Extensive floodplains showing the development of siliciclastic and carbonate lakes mostly represent the t5.2 and t5.3 parts, although the sedimentary characteristics of the former reflect more humid and permanent water conditions. These more humid characteristics are also indicated by the drastic change from calcareous paleosols in t5.1 to smectitic Vertisols in t5.2, which occur in relation to thin layers of lacustrine carbonates, greenish lutites, and hybrid oolitic sandstones of palustrine environments. Stable carbon and oxygen isotope data are consistent with a general tendency towards the arid conditions observed in the Tadart Ouadou t6 Member of the Bigoudine Formation, of fluvial-eolian origin and younger in age. This general tendency is interrupted by at least two humid yet hot intervals characterized by pedogenic carbonates featuring lighter isotope compositions and lacustrine carbonates precipitated under conditions of high temperatures and evaporation rates.

&lt;p&gt;From the end of the Carboniferous onwards, the over-thickened and hot Variscan crust collapsed (late-orogenic collapse), accompanied by the rise of high-grade metamorphic domes along low-angle detachment faults and the development of mainly half-graben or pull-apart type asymmetric intramountain coal basins.&lt;/p&gt; &lt;p&gt;These Carboniferous-Permian late orogenic basins widely developed around 300 Ma and were filled with siliciclastic continental material, accompanied by a widespread intrusive and extrusive magmatic activity. These basins crop out in the internal parts of the belt south of the Variscan Front in several limited locations in and around the Variscan basement of Western Europe (Massif Central, Vosges-Black Forest, Alps, Harz). They occur as small isolated and disconnected &amp;#8220;basins&amp;#8221; with incomplete sedimentary series. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath their Meso-Cenozoic sedimentary covers.&lt;/p&gt; &lt;p&gt;We propose a geological overview of the late Variscan Carboniferous-Permian Br&amp;#233;cy basin (SW Paris basin, France), based on the reprocessing and interpretation of vintage seismic lines and related deep boreholes. We aim (i) to discuss its sedimentary filling, which is hidden beneath the Meso-Cenozoic cover of the Paris basin, (ii) to present thickness maps of its 3.9 km-thick sedimentary filling, and (iii) to describe its structural extensional features related to a syn- to post-rift tectonic scenario. We finally compared our new results to other Carboniferous-Permian deposits in France (to discuss its lateral correlation with neighboring basins) and northwest Europe, suggesting that the Br&amp;#233;cy Basin may represent - due to its thickness and location - a missing link between late Variscan basins in southern and northern Europe.&lt;/p&gt;

The late Carboniferous–early Permian represents a key period in the Phanerozoic history, given the major global geodynamic and climate modifications. The aim of this work is to better understand the context and characteristics of the sedimentation recorded in the continental environments of eastern equatorial Pangea at this time, through the example of the Autun Basin (northeastern Massif Central, France). The Autun Basin contains the historical stratotype of the Autunian continental stage, and its stratigraphy was recently improved by accurate numerical ages. This basin formed in an extensional tectonic context during the latest stages of the Variscan orogeny, and it is essential to study its paleoenvironmental evolution to provide new insights into the sedimentary evolution of contemporaneous surrounding basins. Using field and subsurface data, we propose a refined sedimentological model for the Autun Basin, relying on updated facies interpretations, organic matter content fluctuations, and sequence stratigraphy concepts and correlations. The continental environments of the lower sedimentary succession of the Autun Basin, previously considered to be fluvial and lacustrine, are herein re-interpreted as mainly lacustrine, comprising fine-grained organic matter-rich deposits, and supplied by coarser-grained deltaic siliciclastic sediments, without preservation of strict fluvial sedimentation. The determination of the sequence stratigraphy cycles, strengthened by the quantification of the organic matter content, and reflected by the temporal succession of progradational and retrogradational trends, is used to determine new correlations between several sections, as well as to reconstruct the paleoenvironment evolution at the Carboniferous–Permian transition. This study provides evidence that the sedimentation area of the Autun Basin at the time of its filling was much larger than the preserved basin area, and suggests connections with contemporaneous neighboring French basins, pointing to a large sedimentary system in the northeastern Massif Central area rather than narrow and isolated basins.

In this study, we focused on the formation and preservation processes of colluvial sedimentary breccias within an extensional context. The breccias studied in this work (from Crete and the Pyrenees) are characterized by poorly sorted polygenic deposits of highly angular carbonate clasts whose size ranges from pebbles to blocks measuring several millimeters to several meters. This study shows that the colluvial sedimentary breccias were formed during extensional tectonics and are spatially associated with large-throw normal fault. They are related to the creation of a substantial topography in the footwall of the normal fault followed by its collapse on the hanging wall, leading to fast sediment accumulation and preservation. These breccias are organized, with pebble-to cobble-sized clasts near the slope of the fault while the mega-clasts, such as boulders and blocks, are preserved away from the slope. Such a clast size organization is indicative of a dry rockfall process and is opposite to that of alluvial fan systems dominated by gravity process involving water. This study also revealed that the breccias from the NE of the Pyrenees, encountered on both flanks of the Bas Agly syncline and previously attributed to the Lower Cretaceous, are related to a first phase of extension during the Upper Jurassic.

Late Carboniferous to early Permian organic-rich sedimentary successions of late-orogenic continental basins from the northeastern Massif Central (France) coincide with both the Variscan mountain dismantling and the acme of the long-lasting Late Paleozoic Ice Age. Here, we investigate the carbon and nitrogen cycles in the newly dated sedimentary successions of the Decize–La Machine and Autun basins during these geodynamic and climate upheavals. The sedimentary organic matter has been analyzed through Rock-Eval pyrolysis, palynofacies and elemental and isotope geochemistry along cored-wells and outcropping sections, previously accurately defined in terms of paleo-depositional environments. Rock-Eval and palynofacies data have evidenced two origins of organic matter: a phytoplanktonic/bacterial lacustrine origin (Type I organic matter, organic δ 13 C values around −23.5‰), and a terrestrial origin (vascular land plants, Type III organic matter, organic δ 13 C values around −20‰), mixed in the deltaic-lacustrine sediments during background sedimentation (mean organic δ 13 C values around −22‰). Episodes of high organic matter storage, reflected by black shales and coal-bearing deposits (total organic carbon up to 20 and 70%, respectively) are also recognized in the successions, and are characterized by large negative organic carbon isotope excursions down to −29‰. We suggest that these negative isotope excursions reflect secondary processes, such as organic matter remineralization and/or secondary productivity varying under strict local controls, or possibly larger scale climate controls. At times, these negative δ 13 C excursions are paired with positive δ 15 N excursions up to +10‰, reflecting water column denitrification and anammox during lake-water stratification episodes. Together, these isotopic signals (i.e., low sedimentary organic δ 13 C associated with high bulk δ 15 N values) indicate periods of high primary productivity of surface waters, where nitrogen and carbon cycles are spatially decoupled. These local processes on the sedimentary isotope archives may partially blur our ability to directly reconstruct paleoclimate variations in such continental settings using only C and N isotopes. At last, we explore an organic δ 13 C-based mixing model to propose ways to disentangle autochthonous versus allochthonous origin of organic matter in lacustrine continental settings.