Marine Transgression Research Articles

The Eemian Stage interglacial marine transgression in the south-western Baltic region

Abstract. Through detailed investigations, three sequences of marine and associated deposits in the south-west Baltic area are shown to represent the Eemian interglacial transgression. Pollen analyses and foraminiferal and ostracod analyses are combined to provide the evolution of relative sea-level change. An independent chronology is established by correlation of the pollen record with that from the Bispingen laminated lake deposits in north Germany. Additional published sites from the area are included in a wider reconstruction of events. Ostracod analyses indicate that freshwater lakes initially existed in the basin prior to the marine inundation. This was followed by an early marine transgression. In the south-west Baltic the first marine ingression took place at the base of regional pollen zone E3, with fully marine conditions established in E4 continuing into the lower part of E5. The regression of the sea during zone E6 was followed by freshwater deposition in E7. The linking of the sequences in the south-west Baltic demonstrates that the Eemian transgression occurred both through northern Germany and through the Danish belts–Kattegat seaway, indicating that connections to the North Sea and North Atlantic were present in the area during the maximum interglacial sea-level highstand.

Detecting the late Frasnian semichatovae Event on the deep shelf of North Gondwana

The semichatovae Event is a mid-late Frasnian (Late Devonian) episode of a major marine transgression that coincides with the spread of the conodont Palmatolepis semichatovae . The occurrence of this species and the associated event were therefore proposed to define the Middle-Late Frasnian boundary. As this species is not found on the north Gondwana platforms, this event is only documented on the Laurussia marine outer-shelves. As such, it is not known in the Frasnian reference section within the Upper Quarry Coumiac, located in the Montagne Noire (southern France). In this contribution, we have used a multidisciplinary approach that combines sedimentology, conodont assemblages, magnetic susceptibility, and concentrations of certain elements that are indicative of detrital components to precisely date this event in the absence of Palmatolepis semichatovae by means of global scale correlations. We found that a significant part of the environmental signal has been preserved in the strata, and we could locate the semichatovae transgressive event in the cross-section in the lower part of Zone FZ 11. During this period of recurrent environmental perturbations, conodonts responded to sea-level changes only above a certain depth threshold which is reached only with the semichatovae event.

Provenance and Paleo-Environment of the Late Carboniferous Bauxite Formations in Southern Shanxi

The Carboniferous Benxi Formation in southern Shanxi of North China has significant bauxite resource potential; however, the source of its metallogenic material and its sedimentary environment remain unclear. The microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry methods were applied in this study to examine the mineralogical, petrographic, and geochemical characteristics. Geochemical proxies of La/Y, Sr/Ba, Al2O3/TiO2, Zr/Sc, Th/Sc, La/Sc, and Th/Co were analyzed to investigate the paleo-depositional environment and provenance of the aluminum-bearing strata. The findings indicate that diaspores are the primary ore minerals in bauxite, while kaolinite and rutile are the predominant gangue minerals. Both the bauxite and claystone/aluminous rocks exhibit high enrichment in Li, Bi, and U, with relative enrichment in In, Sb, Th, Nb, and Ta. Li is notably concentrated in the claystone/aluminous rocks, reaching up to 1994.00 μg/g, primarily occurring in cookeite and boehmite, while U is highly concentrated in the bauxite. The aluminum-bearing strata were primarily formed under alkaline-reducing conditions, with changes in acidity and alkalinity of the environment during the sedimentary diagenetic process. Marine transgressions significantly impacted the sedimentary environment of the aluminum-bearing strata, and the paleoclimate was characterized as hot and humid. The principal factors contributing to enrichment of aluminum in the sedimentary basin were the in situ weathering of aluminum-rich source rocks and the transport of clastic materials from high-aluminum source rocks. The source rocks were closely associated with intermediate-acidic magmatic rocks and potentially related to the weathering of Ordovician carbonates.

Carbon, iron and sulfur records of lacustrine paleo-environments during the middle Eocene in eastern China

It is widely recognized that anoxic conditions facilitate the preservation of organic carbon in marine sediments. However, the specific geological factors that lead to the development of such conditions in paleo-lakes are less well understood. Owing to their smaller size, paleolakes could experience more frequent and stronger changes in geochemical conditions than oceans. Such changes, such as volcanism, hydrothermal fluids, or ocean transgressions, can also strongly affect the lacustrine organic carbon burial thereby complicating sediment diagenesis record. Here, we used total organic carbon content (TOC), organic carbon isotope (δ13Corg), iron speciation, and pyrite sulfur isotope (δ34Spy) data to establish relationships between organic carbon preservation and anoxic conditions in fine-grained sediments from the middle Eocene lacustrine depositional environments from the Shahejie Formation of the Jiyang Depression, Bohai Bay Basin, eastern China. The results reveal TOC between 1 % and 10 %, highly-reactive iron to total iron ratios >0.38, and most TOC to total sulfur ratios exceeding 2. These data indicate that the organic-rich shales of the Shahejie Formation were formed as a result of high primary productivity during the warm and humid middle Eocene period, coupled with the efficient preservation of organic matter in anoxic bottom waters. Negative δ13Corg and δ34Spy excursions recorded in the Shahejie Formation indicate water column conditions to have been influenced by transient volcanic eruptions. Positive δ13Corg and negative δ34Spy excursions may have been caused by hydrothermal fluids input whereas δ34Spy values approaching 20 ‰ suggest frequent marine transgressions. In particular, despite potential inputs of S into the paleolake by volcanism, hydrothermal fluids, or marine transgressions, bacterial sulfate reduction efficiently depleted the sulfate pool to have created ferruginous geochemistry water conditions for the effective preservation of organic carbon in sediments. Our results establish a direct link between lacustrine shale geochemical signatures and geological phenomena that impact its sedimentation.

Astronomical Calibration of the Ocean Anoxic Event 1b and Its Implications for the Cause of Mid‐Cretaceous Events: A Multiproxy Record

AbstractThe timing and duration of oceanic disturbances linked to Oceanic Anoxic Event (OAE) 1b, as well as the mechanisms driving anoxia and carbon burial during this period, remain subjects of debate. We conducted cyclostratigraphic analyses on magnetic susceptibility (MS) and elemental Ti and Fe series within the upper Aptian‐lower Albian interval of the Poggio le Guaine core in the Umbria‐Marche Basin, Italy. This interval provides a detailed sedimentary record, supported by variations in magnetic mineral content, Ti, Fe, and significant global shifts in the δ13C curve. Orbital control of MS, Ti, and Fe suggests a duration of 2.84 Myr for the OAE 1b event. Our chronostratigraphic analysis reveals ages of 114.07 ± 0.12 Ma for 113/Jacob, 113.28 ± 0.12 Ma for Kilian, 112.49 ± 0.12 Ma for the central age of the Monte Nerone cluster, 111.70 ± 0.12 Ma for Urbino, and 111.28 ± 0.12 Ma for Leenhardt sub‐events. Stable δ13C chemostratigraphy correlations enable the transfer of tiepoints across various sedimentary basins. Key features of the carbon isotope curves were identified, named, and dated using astrochronology. Our findings suggest that the organic‐rich layers associated with the OAE 1b event exhibit distinct characteristics influenced by several factors, including a warm climate driven by volcanic CO2 emissions, heightened precipitation, intense weathering, and marine transgressions. These factors amplify orbital forcings on paleoclimate changes, leading to oceanic‐atmospheric disturbances that promote deoxygenation and carbon burial during OAE 1b.

Miocene bioerosion in a Cretaceous metamorphic basement from the Arzew Mountains (Oran, northwestern Algeria): First evidence of a Tortonian rocky shore in the southwestern Mediterranean area

Bioerosive trace fossils at the Guessiba Valley (Arzew Mountains) document an ancient Tortonian shoreline cut into Barremian calcschists at the lowermost part of the Tortonian Balanid Marl Formation. Four ichnogenera produced by endolithic bivalves (Gastrochaenolites) and polychaete annelids (Caulostrepsis, Maeandropolydora, Trypanites) have been identified. The four traces consist of dwelling structures (domichnia). The encrusting epifauna on the rockground include acorn barnacles of the genus Balanus and scarce, poorly preserved bivalves. These epibionts exhibit Trypanites and Entobia, respectively. This ichnoassociation identifies the Entobia ichnosubfacies as part of the Trypanites ichnofacies. The fossil rocky shore described in this paper is related to a transgression that occurred during the Tortonian, characterising a stratigraphic surface corresponding to a sequence boundary. The Guessiba Valley succession marks the first Mediterranean marine transgression affecting the southern flank of the Arzew Mountains, characterised by three distinct phases. The calcschists reported here are among the rare examples of non-carbonate rocky substrates colonised by endolithic boring organisms.

Eocene contractional deformation in the NW corner of the Arabian plate and its relation to Arabia-Eurasia collision in SE Türkiye

ABSTRACT Field evidence indicates c. 40 Ma (Early-Middle Eocene) contractional deformation in the S Amanos Mountains. Following latest Cretaceous southward ophiolite emplacement, an intra-platform basin infilled with shallow to deeper marine, dominantly carbonate sediments. Localized thrusting, reverse faulting, and folding were followed by subaerial erosion and non-marine clastic deposition, sealed by an Early Miocene marine transgression. Eocene emergence elsewhere in SE Türkiye probably also resulted from regional crustal shortening. Alternative hypotheses for collision in SE Türkiye propose latest Cretaceous, Mid-Late Eocene, Early Miocene, or Late Miocene suturing of S Neotethys. Much geological evidence in SE Türkiye and NW Iran supports Mid-Late Eocene initial continent-continent collision. Plate reconstructions suggest S Neotethys survived in this region until the Mid-Late Eocene. Biogeographical evidence points to minor Eocene mammal migration across S Neotethys, followed by Early Miocene large-scale terrestrial migrations. Seawater isotopic data suggest a major decrease in inter-Indian Ocean-Mediterranean Sea current flow during the Early Miocene. Instrumental geophysics and both numerical and analogue modelling suggest that the northern Arabian platform underthrust Eurasia (>200 km in S central Iran). In SE Türkiye, Eocene initial ‘soft’ collision was followed by Early Miocene ‘hard collision’, with crustal thickening and exhumation continuing until the Late Miocene, followed by westward ‘tectonic escape’.

Sediment recycling during the Holocene marine transgression in Ría de Vigo (NW Iberia): multiproxy evidence and environmental implications

A new multiproxy study of a 155-cm sediment core located in Ría de Vigo (NW Iberia) recording the transgressive and highstand system tract of the Holocene sea-level rise is presented. New data described include grain size, geochemical analyses, high-resolution qualitative/quantitative analyses of pollen, non-pollen palynomorphs and dinoflagellate cysts content, the qualitative evaluation of diatoms at different key levels and the reconsideration of some seismic interpretations. Besides, 14 radiocarbon dates were obtained from shells and pollen extracts. This new evidence revealed that notable changes in the sedimentation rates and the relative abundance of the different types of palynomorphs occurred during the Holocene. The sediment core studied shows anomalous pollen successions, including unexpected Pinus pollen peaks, during the Early and Middle-Holocene. Differential dating revealed that those anomalous successions correspond to conspicuously aged sediment that has inverted pollen chronologies. Thus, these facies may constitute evidence of redeposition of ancient upland sediments, formed above the ancient coastline at different intervals comprised between the end of the Last Glacial Maximum and the early stages of the Lateglacial, which were rich in very resistant pollen types (Pinus). Dinoflagellate cyst records in combination with the non-reworked pollen evidence reveal a reliable climatic seesaw during the Holocene, includingwet stormy periods of prevailing mixed waters, with strong development of Lingulodinium and high accumulation rates in dinoflagellate cysts, which alternate with other sparsely stormy and drier phases, characterised by the coastal upwelling intensification, well-stratified waters, and increases in Bitectatodinium and Spiniferites spp. but low accumulation rates in dinoflagellate cysts. These climatic dynamics, including a millennial drier cool period that occurred just after the Thermal Optimum are consistent with previous evidence obtained in other limnetic systems in the Iberian Peninsula. Furthermore, there is a delay between the two phases with the highest marine contribution to sediment (ca. 11.0-8.2 and ca. 4.0–3.0 cal ka BP) and the subsequent warm stages when the relative sea level stabilises: the Thermal Optimum (8.0–6.0 ka BP) and the 2.5-0.5 ka BP interval, respectively. Changes in Pinus pollen concentrations and grain size recorded in the postglacial sediments suggest that some upland ancient (Lateglacial) pollen evidence might be remobilised, especially during stages of upwelling intensification, and then resedimented in the seabed. Further studies will be needed to determine if the significant differences existing between the Pinus pollen grain sizes respond to climatic variations affecting the region or have been the result of any replacement of pine species in the area. Nonetheless, Pinus pollen evidence almost disappeared with the first signs of anthropisation in the area, and only recovered after the modern repopulations. Our findings open up new possibilities to further our understanding of sediment reworking and recycling mechanisms through the integration of multiproxy studies encompassing pollen, seismic and sedimentary data.

Description of the Late Holocene South‐east Saline Everglades, Florida palustrine depositional environment with comparisons to other Holocene environments

AbstractA transgressive palustrine depositional model is described for the South‐east Saline Everglades, Florida. The origin, development and termination of freshwater carbonate mud (marl) deposition along the very low gradient Late Pleistocene carbonate ramp are responses to changing rates of rising sea level during the Late Holocene. The onset of the Late Holocene is defined by a decrease in the rate of sea‐level rise from between 2 and 3 to <1 mm year−1. Freshwater marl deposition began with this decrease ca 3165 ± 187 year BP, in a shallow (<0.3 m deep), ephemeral wetland that developed landward of a fringing mangrove forest and is maintained by seasonal Everglades water delivery. Sedimentation kept pace with sea‐level rise forming a 1.2 m thick wedge shaped, landward thinning deposit. The rate of global sea‐level rise began to accelerate ca 1900, the Anthropocene Marine Transgression, and presently the regional rate is 9.4 mm year−1. Saltwater encroachment rates >80 m year−1 are driven by sea‐level rise. Saltwater encroachment resulted in retreat and transformation of coastal communities and their biogenic facies, resulting in a decrease in freshwater wetlands and marl production. Inundation ponding, mangrove overstep and the beginning of submergence are the responses to the accelerating rate of sea‐level rise, however, small scale topographic and tidal ingress differences create considerable variability between Biscayne Bay and Florida Bay coastal basins. The freshwater marl producing habitat will probably be lost within 55 years, and submergence within the next century at the present rate of sea‐level rise. The unique South‐east Saline Everglades depositional environment is compared to other Holocene palustrine depositional environments.

The Holleford structure: Insights into the pre- and post-impact geology of the Frontenac Terrane, Canada

A multi-chronometric investigation has been conducted on the ∼2.0-km-diameter Holleford impact structure of Ontario, Canada. In situ triple quadrupole laser ablation−inductively coupled−mass spectrometry U-Pb and Rb-Sr geochronology, along with (U-Th)/He thermochronology, have been applied to multiple mineral phases from impact melt-bearing breccias and overlying sedimentary units. Impact-induced resetting is absent in all three isotopic systems. While Holleford’s small size resulted in insufficient heating to reset geochronometers during impact, our investigation has defined a more detailed pre- and post-impact geologic setting within the Precambrian basement and overlying Paleozoic lithologies. Target rock age determinations include those associated with the Proterozoic Frontenac Terrane. These are manifest as the Rigolet (1004 ± 5 Ma, U-Pb apatite dating) and Ottawan (1074 ± 12 Ma, Rb-Sr biotite dating) phases of the Grenville Orogeny. Pre-Grenville ages associated with the Penokean (1806 ± 46 Ma, apatite dating) and the Shawinigan (1184 ± 8 Ma, U-Pb titanite dating; 1134 ± 21 Ma, U-Pb zircon dating) orogenies are also retained. A Paleoproterozoic age records Superior Province tectonometamorphism (2421 ± 97 Ma, U-Pb zircon dating). Dated post-impact events include dolomitization associated with Silurian marine transgression (430 ± 14 Ma, U-Pb dolomite dating) and regional K-metasomatism of Mississippian age (346 ± 5 Ma, U-Pb titanite dating). Extremely young (U-Th)/He ages (27−3 Ma) were obtained from planar fractured and recrystallized apatite, which we interpret to be the result of impact-induced diffusion domain reduction. This, combined with low-temperature heating due to burial, significantly limited He retention. Stratigraphic constraints place the Holleford impact event at ca. 458 Ma, close to the Darriwilian−Sandbian boundary of the Ordovician. This age indicates that Holleford may be part of the Late Ordovician group of terrestrial impact craters related to L-chondrite parent breakup.

Possible Indication of the Impact of the Storegga Slide Tsunami on the German North Sea Coast around 8150 cal BP

The Storegga slide tsunami (SST) at ca. 8100 ± 100–250 cal BP is known to be the largest tsunami that affected the North Sea during the entire Holocene. Geological traces of tsunami landfall were discovered along the coasts of Norway, Scotland, England, Denmark, the Faroes and Shetland Islands. So far, the German North Sea coast has been considered as being well protected due to the wide continental shelf and predominant shallow water depths, both assumed to dissipate tsunami wave energy significantly, thus hindering SST propagation dynamics. The objective of our research was to clarify if the SST reached the German Bight and if corresponding sediment markers can be found. Our research was based on the in-depth investigation of a 5 m long section of the research core Garding-2 from Eiderstedt Peninsula near Garding in North Frisia known from a previous study. For this, we newly recovered sediment core Garding-2A at exactly the same coring location as core Garding-2. Additionally, high-resolution Direct Push sensing data were collected to gain undisturbed stratigraphic information. Multi-proxy analyses of sediment material (grain size, geochemical, geochronological and microfaunal data) were carried out to reconstruct palaeoenvironmental and palaeogeographical conditions. We identified a high-energy event layer with sedimentological (e.g., erosional unconformity, rip-up clasts, fining-upward), microfaunal (e.g., strongly mixed foraminiferal assemblage) and other features typical of tsunami influence and identical in age with the SST, dated to ca. 8.15 ka cal BP. The event layer was deposited at or maximum ca. 1–1.5 m below the local contemporary relative sea level and several tens of kilometers inland from the coastline within the palaeo-Eider estuarine system beyond the reach of storm surges. Tsunami facies and geochronological data correspond well with SST signatures identified on the nearby island of Rømø. SST candidate deposits identified at Garding represent the southernmost indications of this event in the southeastern North Sea. They give evidence, for the first time, of high-energy tsunami landfall along the German North Sea coast and tsunami impact related to the Storegga slide. SST deposits seem to have been subsequently reworked and redeposited over centuries until the site was affected by the Holocene marine transgression around 7 ka cal BP (7.3–6.5 ka cal BP). Moreover, the transgression initiated energetically and ecologically stable shallow marine conditions within an Eider-related tidal channel, lasting several millennia. It is suggested that the SST was not essentially weakened across the shallow continental shelf of the North Sea, but rather caused tsunami run-up of several meters (Rømø Island) or largely intruded estuarine systems tens of kilometers inland (North Frisia, this study). We, therefore, assume that the southern North Sea coast was generally affected by the SST but sedimentary signals have not yet been identified or have been misinterpreted. Our findings suggest that the German North Sea coast is not protected from tsunami events, as assumed so far, but that tsunamis are also a phenomenon in this region.

Influence of climate and marine transgression on Mesozoic–Cenozoic diagenesis of clastic rocks in the Tabei Uplift, Tarim Basin, China

The Mesozoic–Cenozoic clastic rocks in the Tabei Uplift form one of the most hydrocarbon-rich zones in the Tarim Basin of China. Understanding how diagenesis has affected the petrophysical properties of the sandstone is crucial for developing regional exploration strategies. Although most studies have investigated the physical conditions during sedimentation and chemical processes during diagenesis, the hydrochemical environment during sedimentation and subsequent diagenesis has received little attention. This study employed petrographic observations, paleo-geothermal reconstructions, and paleoenvironmental analysis to constrain the regional climatic conditions, hydrochemical environment of deposition, and diagenetic features of clastic rocks in the Tabei Uplift. The sandstone at depths of 3500–6000 m is located mainly in the A phase of the middle diagenetic stage, and exhibits three types of diagenesis. Triassic–Jurassic sandstones are dominated by silica, kaolinite, and chlorite cements, Cretaceous sandstones by mainly carbonate cements, and Paleogene sandstones by carbonate and evaporite cements. These diagenetic stages correspond to paleoclimatic changes during the earliest Late Jurassic and the maximum marine transgressions of the Proto-Tethys during the Paleogene, thereby highlighting the influence of climatic change and transgressions on the water conditions during deposition and the type of diagenesis.

Paleoenvironmental conditions across the Coniacian-Santonian in the Kometan Formation, northeastern Iraq: Insights from planktonic foraminifera distribution, mineralogy and geochemistry

The paleoenvironmental conditions during the Coniacian-Santonian interval within the Kometan Formation in northeastern Iraq have been analyzed through the distribution of depth-related planktonic foraminifera in the carbonate rocks (limestone and marly limestone) of the Kometan Formation using standard washing method for soft samples and thin section method for hard samples supported by mineralogical investigations, geochemical analysis and stable isotopic δ13C and δ18O data. The findings indicate that saline marine waters and a hot, dry to semi-arid climate with low to medium oxygen conditions were conducive to deposition, which was characterized by high organic productivity due to marine transgression. The study revealed that the distribution of shallow water forms (SWF) of globular-shaped foraminifera, compared to deep water forms (DWF) of keeled-shaped genera, along with δ13C data from the late Turonian-early Campanian succession, indicated a relatively low sea level throughout the Late Turonian period. The water level began to rise in the early Coniacian, continuing gradually until the late Coniacian, when a noticeable increase in sea level was observed. This elevated sea level persisted through the early and late Santonian periods, before starting to drop. A slight marine transgression was noted at the beginning of the early Campanian period, followed by a significant drop in sea level. During the late Turonian, a subtropical climate prevailed. Temperature increased during the early to middle Coniacian, decreased slightly at the beginning of the late Coniacian, and then rose again at the end of the late Coniacian, indicating a shift from tropical to subtropical climatic conditions. Similar hot climatic conditions persisted in a tropical-subtropical climate during the early to late Santonian and early Campanian, with a relative temperature drop near the end of the early Campanian. No evidence of an oceanic anoxic event (OAE3) was found in the Kometan Formation during the late Coniacian–early Santonian period. The hypothesized event, based on biostratigraphy, facies analysis, stable isotopes, geochemical evidence, and field study, was limited to demonstrating an increase in the ratio of keeled chamber planktonic foraminifera compared to globular chamber ones. This ratio increase of the keeled chamber types is believed to result from a deepening sedimentary environment due to rising sea levels, creating organic matter-rich beds with high productivity and relatively low oxygen conditions during the Coniacian-Santonian boundary.

Paleogeographic reconstruction and sedimentary evolution of tidal-dominated estuarine depositional systems: Insights from the campanian M1 sandstone formation, Oriente Basin, Ecuador

The Oriente Basin is a back-arc basin located east of the Ecuadorian Andes in South America. Evidence suggests that during the Cretaceous period, the basin's margins received a terrigenous shallow marine sedimentation. Due to regional variations in accommodation and depositional controlling factors near a shoreline, the sedimentary environments in the fluvial-marine transitional zones exhibit considerable variability. In this study, we analyzed the sedimentological characteristics of the M1 Sandstone Formation unit (∼83 Ma-72 Ma), which comprises a set of ancient estuarine deposits preserved in the northern part of the basin. We quantified the impact of mixed hydrodynamic processes on the distribution of tidal-dominated estuarine facies and discussed the development conditions and evolutionary processes of an estuarine formation under the background of persistent transgression. Core, well log, and seismic data provide evidence for reconstructing the tidal-dominated estuarine environment. In the core section, we identified 14 lithofacies and 7 major facies association types. The frequent occurrence of sedimentary structures associated with tidal currents indicates that tidal processes extensively reworked the deposits. The spatial distribution trends of facies associations reveal the evolution of mixed hydrodynamic conditions dominated by tidal processes in the estuary and allow us to divide the M1 Sandstone Formation into four depositional periods: the initial development, rapid development, decline, and the post-infilling open coast tidal flat development periods. Furthermore, through a systematic analysis of hydrodynamic conditions and sediment distributions, we identified multiple depositional centers in the tidal-dominated estuary influenced by different hydrodynamic processes. These correspond to the upstream fluvial-dominated tidal point bar depositional region, the middle mixed-energy depositional interaction zone, and the downstream tidal-dominated tidal sand bar depositional region. In these regions, the substantial accumulation of sandy deposits, represented by tidal sand bars, reflects the high accommodation space characteristic of tidal-dominated estuaries. Our findings indicate that the slow subsidence of a broad and gently sloping coastal topography, stable material transport, and sea level change dominated by marine transgression ensured the necessary accommodation for the development of the estuary in the M1 Sandstone Formation. The sedimentological study of the M1 Sandstone Formation provides a case for understanding the sedimentary evolution in fluvial-marine transitional zones.

Geophysical modeling of the middle Bogotá River Basin with support from interpretation of electrical resistivity, gravity, seismic and borehole data to evaluate potential deep aquifers

The main objective of this research was to develop a geological and geophysical modeling to infer the geometry and thickness in the sedimentary sequence of the middle basin of the Bogotá River with emphasis on the Guadalupe Group, reconstructing the stratigraphic sequence, structural setting, hydrogeological modeling, and potential geothermal uses. Various geophysical methods were applied, including vertical electrical soundings (VES), and magneto telluric soundings (MT-VES), whose results were complemented with the interpretation of seismic lines, regional and local gravity anomaly maps, and borehole data, among others, which allowed to model the subsurface from the surface to depths beyond 3000 meters, with emphasis on the interval between 500m to 1000m depth. Integrated models were developed from interpretations of electrical resistivity data, gravity and magnetic data, reflection seismic and borehole data. Based on the results, potential deep aquifers have been proposed to be confirmed by drilling. These deep aquifers can contribute to satisfy the need for water, which historically has been explored and overexploited from shallower aquifers in this sector of the basin. A recommendation was also made to consider the potential of low enthalpy thermal energy for agro-industrial purposes associated with groundwater’s temperature at the depth of this research. As a result, the modeled sedimentary sequence is characterized by a thick quaternary overburden overlying an intensively folded and faulted Neogene, Paleogene, and upper Cretaceous formations, mainly composed of siltstone, sandstones, and shale sequences of fluvial and marine environment, including facies of marine regressions and transgressions near the coastline. The penetration obtained allows establishing a high hydrogeological potential in the first 2000m depth, especially associated with the Guadalupe group, where the Labor and Tierna and Arenisca Dura formations have the highest hydrogeological potential. In addition, the preliminary estimation of thermal gradients suggest that low enthalpy geothermal energy potential is feasible to be used for the agro-industrial demand of energy of the study area.

Paleoenvironmental Transition during the Rhuddanian–Aeronian and Its Implications for Lithofacies Evolution and Shale Gas Exploration: Insights from the Changning Area, Southern Sichuan Basin, South-West China

During the Rhuddanian–Aeronian interglacial period, global geological events such as glacial melting, synsedimentary volcanic activity, biological resurgence, and large-scale marine transgressions caused frequent fluctuations in paleoproductivity, climate changes, and sea level variations. These paleoenvironmental transitions directly influenced the development characteristics of shale lithofacies. This study investigates the Longmaxi Formation shale in the Changning area in the Southern Sichuan basin, focusing on 28 core samples from Well N1. Using scanning electron microscopy, QEMSCAN, TOC, XRD, and major and trace element analyses, we reconstructed the paleoenvironmental transitions of this period and explored their control over shale lithofacies types and mineral compositions. Four shale lithofacies were identified: carbonate rich lithofacies (CRF), biogenic quartz-rich lithofacies (BQRF), detrital clay-rich lithofacies (CRDF), and detrital quartz-rich lithofacies (DQRF). During the Rhuddanian period, rising global temperatures caused glacial melting and rapid marine transgressions. The low oxygen levels in bottom waters, combined with upwelling and abundant volcanic material, led to high paleoproductivity. This period primarily developed BQRF and CRF. Rich nutrients and abundant siliceous organisms, along with anoxic to anaerobic conditions, provided the material basis and preservation conditions for high biogenic quartz and organic matter content. High paleoproductivity and anoxic conditions also facilitated the precipitation of synsedimentary calcite and supplied Mg2+ and SO42− for the formation of iron-poor dolomite via sulfate reduction. From the Late Rhuddanian to the Mid-Aeronian, the Guangxi orogeny caused sea levels to fall, increasing water oxidation and reducing upwelling and volcanic activity, which lowered paleoproductivity. Rapid sedimentation rates, stepwise global temperature increases, and the intermittent intensification of weathering affected terrigenous clastic input, resulting in the alternating deposition of CRF, CRDF, and DQRF. Two favorable shale gas reservoirs were identified from the Rhuddanian–Aeronian period: Type I (BQRF) in the L1–L3 Layers, characterized by high TOC and brittleness, and Type II (DQRF) in the L4 Layer, with significant detrital quartz content. The Type I-favorable reservoir supports ongoing gas production, and the Type II-favorable reservoir offers potential as a future exploration target.

Facies architecture, pedogenesis and palynology of the Olenekian dryland setting – A sedimentary record of Early Triassic climate oscillations in the SE Germanic Basin

The Early Triassic period was characterised by significant climatic perturbations driven by generally high global temperatures. Several significant shifts in the stable carbon and oxygen isotopes were recognised in the marine settings in the Olenekian age deposits that were linked to short-lasting but relatively high-amplitude climatic events. The record of these events in the continental strata is far less understood due to the stratigraphic incompleteness of such deposits. However, in the Holy Cross Mountains (Poland), the Olenekian continental deposits are well preserved, and sedimentation was relatively continuous, making them an ideal candidate for studying the effects of climate changes and their preservation in continental settings. As such, sedimentological analysis of five wells and one outcrop (over 530 m logged in total), integrated with new and legacy palynological data, allowed the reconstruction and dating of major steps in the palaeoenvironmental evolution of the SE part of the Central European (Germanic Basin), and its comparison with the marine-based climatic models for the Early Triassic. The lower and middle Olenekian stage is represented by fine-grained deposits of dry floodplain interbedded with sandstones deposited within fluvial distributary channels and terminal splays. The palaeosols are mainly represented by aridisols (calcisols), indicating a relatively dry, though not extreme, climate as some water was necessary to support relict plant cover. Towards the mid-Spathian times, the climate became more humid - lacustrine deposits appeared, and palaeosols displayed features of an elevated water table (gleyed vertisols and inceptisols). Frequent storms and floods also affected the lacustrine sedimentation, reflecting volatile climatic conditions. In the late Spathian time, continental sedimentation continued, and the dominance of vertisols and more stacked fluvial channels in the sequence is linked with an increased seasonality, with more pronounced humid seasons. The continental setting lasted until the latest Spathian time, when a marine transgression occurred, marking a new phase in the basin development.

Micropaleontological and sedimentological analyses of carbonates rocks in parts of Sokoto Basin, Nigeria: implications for paleoecological interpretation and exploration efforts

This study presents a detailed analysis of the Paleocene and Maastrichtian marine sediments in the Sokoto Basin, Nigeria, using boreholes GSN – BH – 2051 and GSN – BH – 4051, respectively. This study is aimed at integrating sedimentological, micropaleontological and petrographic data in paleoecologic interpretation of depositional environments of the Sokoto Basin. The methods adopted in this research involved the examination of ditch cuttings, carbonate thin sections, and microfossils analyses from the boreholes drilled in Sokoto Basin. The sedimentological data from the borehole showed that the studied stratigraphic unit comprises mainly fine to medium-grained limestone facies, sparitic intraclastic packstone and oolitic-elmicrite wackestone facies. The microfacies obtained from petrography data revealed micro-fossils abundance and diversity associated with the onset of shallow marine transgression which resulted in the deposition of the Dange and Kalambaina Formations, respectively. The assemblages of the larger foraminifera (Opercullnoides bermudezi) and the larger ostracod (Bairdia iIaroensis) in the borehole sections further suggested marginal marine depositional environment for the Kalambaina and Gamba Shale Formations. The paleoecological interpretation suggests varying salinities and dysaerobic conditions during deposition, with implications for understanding basin evolution. The study concludes by highlighting the importance of integrating multiple methods for a detailed understanding of paleoecological and depositional environment of Sokoto sedimentary basin.

Reconciling short- and long-term measurements of coastal cliff erosion rates

Oblique terrestrial laser scanning (TLS) enables topographic change detection at scales (10−1 –100 cm) that are appropriate for coastal cliff erosion monitoring. Despite this, published applications of TLS on cliff are limited to a small number of sites around the world. Here we report new TLS point cloud datasets from 9 years of monitoring (2014–2023) at Rothesay Bay within the Hauraki Gulf, New Zealand, which has relatively low wave energy and a meso-tidal range. The 120 m-length scan area includes cliffs of 10–30 m height, formed of horizontally bedded soft sedimentary flysch rock. The cliffs are fronted by an 140 m wide near-horizontal shore platform that terminates in an abrupt seaward edge. Previous research at this site has estimated long-term cliff erosion rates within a range of 1.4 ± 0.1 to 14.3 ± 0.1 mm/year on the basis of measured shore platform width, assuming that the shore platform has widened over time over 6000 years of stable Holocene sea level, and that the seaward edge of the shore platform has not retreated. Volumetric cliff-face erosion rates were detected through 17 scans over a 9-year window (2014–2023), including intensive monthly TLS scanning between July 2021 and July 2022. Results show that the average cliff recession rate over the past decade has been 41 ± 2 mm/year, and monthly scans show a range in erosion rates of 30 to 288 mm/year. The cliff recession rate detected with TLS is 3 to 30 times higher than erosion rates derived based on the shore platform width. If erosion had been constant at this rate over approximately 6000 years, a total cliff retreat of >245 m would be expected, whereas the contemporary shore platform is only 140 m wide. We discuss two possible hypotheses for the confounding width of the modern shore platform: 1) that modern cliff retreat rates are faster than past erosion rates; 2) that the seaward edge of the shore platform does not reliably demarcate Holocene cliff recession. We present new bathymetric survey mapping seaward of the shore platform edge that reveals multiple rocky features that are distinguished by steep slope breaks and planar surfaces. Understanding the evolution of the intertidal shore platforms during the Holocene era may necessitate new insights on how cliffs formed toward the end of the last marine transgression. This could potentially be investigated through the study of subtidal marine bathymetry.

Sedimentology and structure of the Paleogene Nummulitic series of Corsica: Reconstruction of the southern termination of the western Alpine foreland basin

AbstractNummulitic Limestones deposits are preserved along the tectonic contact between the Variscan basement and Alpine units of Corsica. These marine carbonates, dated from the Late Palaeocene to the Middle Eocene, were deposited within a foreland flexural basin that is considered to be the southern continuation of the Alpine foreland basin of southeast (SE) France. However, in contrast with the Nummulitic Limestones of SE France, those of Corsica are far less documented. This field‐based study constrains the sedimentology, stratigraphy and structure of the Nummulitic Limestones of Corsica in three localities (Balagne, Corte and Sari‐Solenzara) to identify factors that controlled foreland basin development and to clarify its significance within the early alpine orogen. The microfacies, microfaunal assemblages and siliciclastic fractions are characterised throughout the succession at each locality. The results indicate the existence of an important Variscan basement relief to the west of the basin (West Corsican Massif) that supplied early alluvial fans found at the base of the foreland succession in the northernmost Balagne area. Continuous high clastic input strongly reduced the development and diversity of the overlying Nummulitic Limestones facies and fauna. Further south, limestones in the Corte and Sari‐Solenzara areas are thicker and contain richer fauna. Three depositional models corresponding to the carbonate ramp system are proposed for the Nummulitic Limestones and used to construct paleogeographic maps illustrating the transgressive evolution of the Corsican foreland basin from the Early to the Late Eocene. Based on our results and available regional tectonic data and LT thermochronological data, we propose that the Nummulitic marine transgression took place within a continuous foreland basin encompassing southern Corsica and SE France during the early development of the western alpine arc.