<p>Down-hole fractionation (DHF), a known phenomenon in static spot laser ablation, remains one of the most significant sources of uncertainty for laser-based geochronology. A given DHF pattern is unique to a set of conditions, including material, inter-element analyte pair, laser conditions, and spot geometry. Current modelling methods (simple or multiple linear regression, spline-based regression) for DHF do not readily lend themselves to uncertainty propagation, nor do they allow for quantitative inter-session comparison, let alone inter-laboratory or inter-material comparison.</p>
<p>In this study, we investigate the application of orthogonal polynomial decomposition for quantitative modelling of LA-ICP-MS DHF patterns. We outline the algorithm used to compute the models, apply it to an exemplar U–Pb dataset across a range of materials and analytical sessions, and finally provide a brief interpretation of the resulting data.</p>
<p>In this contribution we demonstrate the feasibility of quantitative modelling and comparison of DHF patterns from multiple materials across multiple sessions. We utilise a relatively new data visualisation method, uniform manifold approximation and projection (UMAP), to help visualise the data relationships in this large dataset while comparing it to more traditional methods of data visualisation.</p>
<p>The algorithm presented in this research advances our capability to accurately model LA-ICP-MS DHF and may facilitate reliable decoupling of the DHF correction for non-matrix-matched materials, lead to improved uncertainty propagation, and facilitate inter-laboratory comparison studies of DHF patterns.</p>
<p>The generalised nature of the algorithm means it is applicable not only to geochronology but also more broadly within the geosciences where predictable linear (<span class="inline-formula"><i>x</i></span>-to-<span class="inline-formula"><i>y</i></span>) relationships exist.</p>
F. W. Jakobsen, F. W. Jakobsen, M. Winsborrow
et al.
<p>Amplified Arctic warming is triggering dramatic changes to the Greenland Ice Sheet (GrIS). Studying past warm periods can provide process insights valuable to predictions of future ice sheet response. Miocene (23.03–5.33 <span class="inline-formula">Ma</span>) and Pliocene (5.33–2.58 <span class="inline-formula">Ma</span>) global climatic records include periods of warmer than present temperatures thought to represent analogues to near-future scenarios. Despite this, the details of the long-term glacial history of the eastern and northeastern sectors of Greenland are still largely unresolved. Here, we use seismic reflection and borehole data to describe the late Cenozoic glacial architectural development of the Northeast Greenland continental margin and thereby reconstruct long-term ice sheet evolution. We identify three key unconformable seismic surfaces that define three mega units of predominantly glacial origin. Two of the surfaces are for the first time correlated across the entire outer Northeast Greenland margin and tied to both Ocean Drilling Program Site 909 and Site 913. We show that the Late Miocene onset of shelf progradation occurs around 6.4 <span class="inline-formula">Ma</span>, marking the first recorded advance of grounded ice masses across the NE Greenland shelf, forming depocentres (trough mouth fans) beyond the palaeo-shelf edge. Subsequently during the Late Miocene and Early Pliocene, the GrIS expands multiple times across the shelf, extending the continental shelf seawards. Based on the development of more extensive and thicker depocentres along the entire outer shelf and upper slope, we suggest an intensification of shelf glaciations sometime after <span class="inline-formula">∼</span> 4.1 <span class="inline-formula">Ma</span>, possibly coinciding with the intensification of the Northern Hemisphere glaciations (3.6–2.7 <span class="inline-formula">Ma</span>).</p>
Permochoristidae is a megadiverse mecopteran group that has mainly been reported from Russia and Australia, whereas records from China remain scarce. In this report, two new species of <i>Mesochorista</i> are described and illustrated from the Guadalupian Yinping Formation, Eastern China. <i>Mesochorista tillyardi</i> Lian and Huang, sp. nov. is characterized by the forewing covered with dense oval spots, and Sc<sub>1</sub> closely approximal to R<sub>1</sub> and connected by a short sc-r crossvein. <i>Mesochorista yinpingensis</i> Lian and Huang, sp. nov. is characterized by the forewing covered with dense irregularly colored patches, Sc<sub>1</sub> devoid of expanded area, and M with only five branches. Based on a detailed discussion of the type species and other co-occurring species of <i>Mesochorista</i> and <i>Permochorista</i>, in light of the new insights into Sc<sub>3</sub>, we support that <i>Permochorista</i> is a junior synonym of <i>Mesochorista.</i>
<p>Melting polar and alpine ice sheets in response to global warming pose ecological and societal risks but will also hamper our ability to reconstruct past climate and atmospheric composition across the globe. Since polar ice caps are crucial environmental archives but highly sensitive to ongoing climate warming, the Arctic and Antarctic research community is increasingly faced with melt-affected ice cores, which are already common in alpine settings of the lower latitudes.</p>
<p>Here, we review the characteristics and effects of near-surface melting on ice-core records, focusing on a polar readership and making recommendations for melt-prone study regions. This review first covers melt layer formation, identification and quantification of melt, and structural characteristics of melt features. Subsequently, it discusses effects of melting on records of chemical impurities, i.e. major ions, trace elements, black carbon, and organic species as well as stable water isotopic signatures, gas records, and applications of melt layers as environmental proxies.</p>
<p>Melting occurs during positive surface energy balance events, which are shaped by global to local meteorological forcing, regional orography, glacier surface conditions and subsurface characteristics. Meltwater flow ranges from homogeneous wetting to spatially heterogeneous preferential flow paths and is determined by temperature, thermal conductivity and stratigraphy of the snowpack. Melt layers and lenses are the most common consequent features in ice cores and are usually recorded manually or using line scanning. Chemical ice-core proxy records of water-soluble species are generally less preserved than insoluble particles such as black carbon or mineral dust due to their strong elution behaviour during percolation. However, high solubility in ice as observed for ions like F<span class="inline-formula"><sup>−</sup></span>, Cl<span class="inline-formula"><sup>−</sup></span>, NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="43bba5feeea5818072376b211f2a452d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-18-2691-2024-ie00001.svg" width="8pt" height="15pt" src="tc-18-2691-2024-ie00001.png"/></svg:svg></span></span> or ultra-trace elements can counteract the high mobility of these species due to burial in the ice interior. Stable water isotope records like <span class="inline-formula"><i>δ</i><sup>18</sup></span>O are often preserved but appear smoothed if significant amounts of meltwater are involved. Melt-affected ice cores are further faced with questions about the permeability of the firn column for gas movement, and gas concentrations can be increased through dissolution and in situ production. Noble gas ratios can be useful tools for identifying melt-affected profile sections in deep ice. Despite challenges for ice-core climate reconstruction based on chemical records, melt layers are a proxy of warm temperatures above freezing, which is most sensitive in the dry snow and percolation zone.</p>
<p>Bringing together insights from snow physics, firn hydrology, and ice-core proxy research, we aim to foster a more comprehensive understanding of ice cores as climate and environmental archives, provide a reference on how to approach melt-affected records, and raise awareness of the limitations and potential of melt layers in ice cores.</p>
<p>Magma-poor rifted margins, and their corresponding potential zones of exhumed serpentinized mantle, represent a unique class of tectonic boundaries with enormous promise for advancing the energy transition, such as with hydrogen production and carbon sequestration and in the search for critical minerals. In this study, a synthesis of the results from seismic refraction and wide-angle reflection (RWAR) profiling and resulting velocity models across the continent–ocean transitions of the southern North Atlantic Ocean is presented. The models are assessed and compared to understand characteristic basement types and upper mantle behaviour across the region and between conjugate margin pairs and to calibrate how their continent–ocean transition zones (COTZs) are defined. Ultimately, this work highlights the variable nature of continent–ocean transition zones, even within the magma-poor rifted margin end-member case, and points to avenues for future research to fill the knowledge gaps that will accelerate the energy transition.</p>
Esperanza Cerdeño, Natalia P. Lucero, Jorge O. Chiesa
This is an updated contribution to the Quaternary geology and paleontology from central-western Argentina, focused on San Luis Province. It is mostly based on unpublished data; only some fossils had previously been briefly mentioned in broader faunal contexts. The fossil-bearing sediments correspond to eolian and alluvial environments of moderate energy, dominated by sands and sandy silts. They overlie high-energy fluvial cycles and underlie edaphic horizons. They have a wide distribution, and several radiocarbon dates allow their regional correlation. Stratigraphic sequences with the precise origin of fossils allow for the improvement of lithostratigraphic and faunal correlations with the Pampean Region (central and east Argentina; La Pampa and Buenos Aires provinces), where Pleistocene assemblages are better known, but also with central-western (Cuyo Region), northwestern, and northeastern Argentina. Faunal remains correspond to large mammals, represented by xenarthrans (Cingulata and Tardigrada), macraucheniids (Litopterna), gomphotheres (Proboscidea), and equids (Perissodactyla), a typical Pleistocene mixture of native (xenarthrans and litopterns) and immigrant mammals.
Rafed Al-Muhamed, Mazin Al Shaoosh, Nagham Al Hawi
Twenty oil wells were selected to study the tectonostratigraphic of the Cretaceous in southern Iraq, in order to develop a comprehensive description of the petroleum system in the region. That was conducted through an interpretation of the technical reports and the available information of the wells, which include sedimentary, stratigraphy, tectonic reports, and oil reservoir studies of the Cretaceous. Stratigraphically, a third order cycle was identified in the Cretaceous succession in southern Iraq, which also comprises seven and half cycles of the fourth order. Eight genetic stratigraphic sequences were also identified, as well as eight maximum flooding surfaces. The concept of the tectonostratigraphic boundary (TSB) and the tectonostratigraphic unit (TSU) has been adapted in this study. In the present study, the Cretaceous period in southern Iraq considers one tectonostratigraphic system (TSS) consisting of four main tectonostratigraphic categories. Each category consists of a set or group of secondary tectonostratigraphic units; these are TSU1A, TSU1B, TSU1C, TSU1D-TSU2A, TSU2B-TSU3A, TSU3B, TSU3C-TSU4A, TSU4B, and TSU4. These units are separated by five tectonostratigraphic boundaries presented from TSB1 to TSB5 by Sulaiy, Shuaiba, Mauddud, Khasib, lower part of Tanuma, and Shiranish. The lateral extensions of the TSUs that are close to the passive margin (northeast part of the study area) are hydrocarbon reservoirs. The lateral extensions TSUs that are far from the passive margin (southwest part of the study area) are hydrocarbon generator source. The intermediate unite is characterized as both a generator source and reservoir hydrocarbon. Vertically, the TSUs are characterized by improved reservoir properties with reduced depth due to the lack of compressional tectonic force, which leads to forming a good primary porosity. The transfer from north to south of the study area represents a trend of improvement in reservoir characteristics for the same reason as mentioned previously. Finally, the TSB represents a source generator hydrocarbon more than a reservoir.
Cyril Mayaud, Blaž Kogovšek, Franci Gabrovšek
et al.
Poljes are flat closed karst depressions prone to regular flooding. The floods can be several meters high, last for months and damage significantly human infrastructures. To predict the maximum level reached, the polje water balance needs to be implemented. This technique encounters the difficulty that important part of the inflow and outflow flowing through many poljes is ungauged, as it is challenging to measure accurately the numerous springs and ponors activating temporarily with the rise of water level. This work aims to see whether this problem can be handled and the polje water balance reconstituted. To do so, a typical Dinaric polje is equipped with several water level stations installed over its surface and in the nearby water active caves. Combining a 1*1m digital elevation model of the polje surface with water levels and inflow records of the main two springs allowed assessing the variation of flooded volume and reconstructing the water balance. The highest total inflow values reached during the observed period were of about 140-150 m3/s, with up to a third of it being ungauged. In addition, the effect of a large estavelles group on the polje inflow and outflow could be identified, and helped to characterize the outflow, with values comprised between 65 and 75 m3/s. Finally, intense rainfall over the polje flooded surface showed to be a temporary important source of inflow. The values found by the water balance analysis have been used as input and calibration data in a numerical model reproducing the flood dynamics in the polje and its surrounding aquifer. Results validated both polje water balance and conceptual hydrogeological model. They justify the significance of combining water level measurements with a digital elevation model to monitor the floods. The method can be applied to other poljes flooding in a complex way of superposed input and output signals. Finally, the places to be equipped in priority if the polje has no measurement network or if available funding is limited are discussed.
Nikolaos Dimopoulos, Elena Zoumpouli, Nicolina Bourli
et al.
The studied section, up to 10 m thick with 17 different carbonate beds, showed the interaction between a giant slide and the pre-existing normal faults during the upper Cretaceous time. There are three major points of consideration in the studied section: (1). The presence of two slump horizons, up to 1 m thick each, within the stratigraphic column, related to the basin floor instability, due to normal listric faults activity. (2). The presence of many normal, with listric geometry, faults, with an ESE–WNW direction, and mostly west-dipping. These faults acted during the sedimentation processes and produced the basin floor inclination for the slumping when still the sediments were unconsolidated. This tectonic activity seems to terminate in the upper part of the stratigraphic column. (3). After the development of the slumps and the normal faults’ activity, which produced a displacement of up to 30 cm, a new event was characterized in the region. The completely studied block probably rotated to the west and thus the instability of the sediments produced a giant slide, up to 7 m thick and with movement up to 0.9 m, cutting the pre-existing normal faults. The knowledge of the regional evolution, with extensional tectonics during the Jurassic to early Miocene periods, which was inverted to a compressional regime during the middle Miocene, as well as the presence of a major normal fault along the studied section with an NNW–SSE direction, suggested that the studied section was situated on the hanging wall of the above fault during the extensional regime.
This paper presents a list of >100 publicly known late Quaternary proboscidean sites that have certain or possible traces of hominin utilization in Africa, Europe, and Asia, along with a sample of references, chronometric or estimated ages, and brief descriptions of the associated materials and bone modifications. Summary discussions of important sites are also presented. Lower Palaeolithic/Early Stone Age hominins created far fewer proboscidean site assemblages than hominins in later Palaeolithic phases, in spite of the time span being many times longer. Middle Palaeolithic/Middle Stone Age hominins created assemblages at eight times the earlier hominin rate. Upper Palaeolithic/Later Stone Age hominins created site assemblages at >90 times the rate of Lower Palaeolithic hominins. <i>Palaeoloxodon</i> spp. occur in nearly one third of the sites with an identified or probable proboscidean taxon and <i>Mammuthus</i> species are in nearly one half of the sites with identified or probable taxon. Other identified proboscidean genera, such as <i>Elephas</i>, <i>Loxodonta</i>, and <i>Stegodon</i>, occur in few sites. The sites show variability in the intensity of carcass utilization, the quantity of lithics bedded with bones, the extent of bone surface modifications, such as cut marks, the diversity of associated fauna, and mortality profiles.
Alexander Jan Dimitris Westra, Changhong Miao, Ioannis Liritzis
et al.
Disasters do and have happened throughout human existence. Their traces are found in the environmental record, archaeological evidence, and historical chronicles. Societal responses to these events vary and depend on ecological and cultural constraints and opportunities. These elements are being discovered more and more on a global scale. When looking at disasters in antiquity, restoring the environmental and geographical context on both the macro- and microscale is necessary. The relationships between global climatic processes and microgeographical approaches ought to be understood by examining detailed societal strategies conceived in response to threatening natural phenomena. Architectural designs, human geography, political geography, technological artefacts, and textual testimony are linked to a society’s inherited and real sense of natural threats, such as floods, earthquakes, fires, diseases, etc. The Shang and Mycenaean cultures are prime examples, among others, of Bronze Age societies with distinctive geographical, environmental, and cultural features and structures that defined their attitudes and responses to dangerous natural phenomena, such as floods, earthquakes, landslides, and drought. By leaning on two well-documented societies with little to no apparent similarities in environmental and cultural aspects and no credible evidence of contact, diffusion, or exchange, we can examine them free of the onus of diffused intangible and tangible cultural features. Even though some evidence of long-distance networks in the Bronze Age exists, they presumable had no impact on local adaptive strategies. The Aegean Sea and Yellow River cultural landscapes share many similarities and dissimilarities and vast territorial and cultural expansions. They have an apparent contemporaneity, and both recede and collapse at about the same time. Thus, through the microgeography of a few select Shang and Mycenaean sites and their relevant environmental, archaeological, and historical contexts, and through environmental effects on a global scale, we may understand chain events of scattered human societal changes, collapses, and revolutions on a structural level.
Jarred C. Lloyd, Alan S. Collins, Morgan L. Blades
et al.
Continental rifts have a significant role in supercontinent breakup and the development of sedimentary basins. The Australian Adelaide Superbasin is one of the largest and best-preserved rift systems that initiated during the breakup of Rodinia, yet substantial challenges still hinder our understanding of its early evolution and place within the Rodinian supercontinent. In the past decade, our understanding of rift and passive margin development, mantle plumes and their role in tectonics, geodynamics of supercontinent breakup, and sequence stratigraphy in tectonic settings has advanced significantly. However, literature on the early evolution of the Adelaide Superbasin has not been updated to reflect these advancements. Using new detrital zircon age data for provenance, combined with existing literature, we examine the earliest tectonic evolution of the Adelaide Superbasin in the context of our modern understanding of rift system development. A new maximum depositional age of 893 ± 9 Ma from the lowermost stratigraphic unit provides a revised limit on the initiation of sedimentation and rifting within the basin. Our model suggests that the basin evolved through an initial pulse of extension exploiting pre-existing crustal weakness to form half-grabens. Tectonic quiescence and stable subsidence followed, with deposition of a sourceward-shifting facies tract. Emplacement and extrusion of the Willouran Large Igneous Province occurred at c. 830 Ma, initiating a new phase of rifting. This rift renewal led to widespread extension and subsidence with the deposition of the Curdimurka Subgroup, which constitutes the main cyclic rift sequence in the Adelaide Superbasin. Our model suggests that the Adelaide Superbasin formed through rift propagation to an apparent triple junction, rather than apical extension outward from this point. In addition, we provide evidence suggesting a late Mesoproterozoic zircon source to the east of the basin, and show that the lowermost stratigraphy of the Centralian Superbasin, which is thought to be deposited coevally, had different primary detrital sources.
<p>Big data are significant for quantitative analysis and contribute to
data-driven scientific research and discoveries. Here a brief introduction
is given to the Geobiodiversity Database (GBDB), a comprehensive
stratigraphic and palaeontological database, and its data. The GBDB includes
abundant geological records from China and has supported a series of
scientific studies on the Paleozoic palaeogeography and tectonic and
biodiversity evolution of China. The data that the GBDB has including those that are newly
collected are described in detail; the statistical results and structure of
the data are given. A comparison between the GBDB; the largest
palaeobiological database, the Paleobiology Database (PBDB); and the geological rock database Macrostrat is drawn. The GBDB and other databases are complementary in
palaeontological and stratigraphic research. The GBDB will continually provide users access to detailed palaeontological and
stratigraphic data based on publications. Non-structured data of palaeontology and stratigraphy will also be included in the GBDB, and they
will be organically correlated with the existing data of the GBDB, making
the GBDB more widely used for both researchers and anyone who is interested
in fossils and strata. The GBDB fossil and stratum dataset (Xu, 2020) is
freely downloadable from <a href="https://doi.org/10.5281/zenodo.4245604">https://doi.org/10.5281/zenodo.4245604</a>.</p>
The Borghetto d' Arroscia sequence begins with a little known basel post, followed by two lithostratigraphic Units: the M. Bignone Quartzites (Paleocene ? —Eocene ? ) and the Ubaga Limestones (Eocene).
Three deformation phases affected the tectonic evolution of the Borghetto d'Arroscia element. They are shown by the minor structures (at outcrop scale) and by the major ones, surveyed at 1/10.000 scale. The first two phases are vergent outwards. The former (Fl ) is characterized by southvergent recumbent folds, the latter (Fl b) gives cut planes slightly dipping, forming the overthrust surface to the same direction. The third phase (F2) is retrovergent and does not change the general structural setting already reached.
Jama leži v Matarskem podolju, v SZ delu Slovenije. Okolico sestavljajo apnenci ter apnenčaste breče kredne starosti. Njen vhodni del je udornega nastanka in leži v večji vrtači, jama pa se konča s podorom pod drugo vrtačo. Nad osrednjim delom jame je tudi manjša vrtača; posledica je, da je v tem delu obilnejša siga. Očitne so poškodbe zaradi zmrzali, ki segajo globoko v jamo; v vhodnem delu so značilni pojavi plazenja krioklastičnega grušča. Jama je sprva nastajala v freatčnih, nato pa v epifreatičnih pogojih. Izračunan nekdanji pretok kaže na veliko količino vode.
Cave lies in Matarsko podolje, in southwestern part of Slovenia. Surrounding beds are composed of limestones and limestone breccias of Cretaceous age. In the vicinity there are many dolines and collapse dolines. The entrance and final part of the cave are situated directly under the big dolines. Because of the small doline, which can be found above the middle part of the cave, there are many flowstone features. Obvious damages due to the freezing and thawing are found along the most part of the cave, at the entrance there is a lot of cryoclastic gravel. Cave began to form in phreatic and later in epiphreatic conditions. Palaeoflow discharge indicates great amount of water.
A geophysical survey using vertical electrical sounding (VES) was undertaken within the University of Benin (Ugbowo Campus) in an attempt to ascertain aspects of the hydrogeological parameters for groundwater exploitation. Six (6) vertical electrical soundings with electrode spacing of 215m AB/2 were occupied along the traverse, with the aid of ABEM SAS 1000 Terrameter set. The data were interpreted using the IXID and 3-D fieldmap computer softwares. The subsurface stratigraphy is as follows; (262.43-784.7m); topsoil, (205.65-3666.4m); wet laterite, (44.017-2201m); anomalous soil, (601.03-1450m); clayed/silty sand, (2712.38-11741m); dry sand, and (2909.7-12423m); as aquifer. The results reveal depth to water table ranges of 31.2-65.5m. The range of values of minimum thickness of the aquifer across the VES is from 45-63m. VES 3 is the shallowest and may be the cheapest to drill and install a borehole. VES 6 with a inferred depth of 63-65.5m, will probably be the best area to site a borehole in spite of the expected cost imperatives. The area shows slight spatial variations and plausibly attests to natural inhomogeneity, anthropogenic interplay in the course of the development of the area via
construction, and very marginal susceptibility to contamination from the health centre and hostels within the study area. Furthermore, the results conformed to those of previous writers who described the aquifer as sandy and highly prolific
The archaeological works carried out at Buenavista (Lanzarote) have shown a big rectangular structure inside an stratigraphic sequence with a number of artifacts and chronology fluctuating between 10th Century BC and 3rd Century AD. The dates are new for Canarian protohistory, as well as the fact that organic remains associated to Phoeno-Punic materials (pottery, copper and bronze objects and a glass seed) have been found. The goal of this paper is to present a synthesis of the archaeological works at Buenavista showing stratigraphy, chronology and material record.