Sequence Stratigraphy Research Articles

The intrinsic rarity of equilibrium response in stratigraphic processes

Conventional sequence stratigraphy is based, explicitly or implicitly, on the hypothesis that steady external forcing results in a steady stratigraphic configuration (equilibrium response), so that an unsteady stratigraphic configuration is usually believed to result from unsteady external forcing. Recent advances in autostratigraphy, on the other hand, have led to a significantly different notion that steady external forcing generally results in an unsteady stratigraphic configuration (non-equilibrium response). To advance this debate, it is necessary to clarify what exactly is meant by a steady stratigraphic configuration. Here, we propose a quantitative criterion for defining the latter concept in terms of the straightness of the shoreline trajectory, and specifically a straight shoreline trajectory or the shoreline being held still as a sign to express steady stratigraphic configurations. In such a definition, a steady stratigraphic configuration means that the ratio of the rate of aggradation and the rate of progradation is constant, or one of these two rates is zero. Based on this criterion, a total of 7 types of steady stratigraphic configurations can be clarified, most of which require unsteady external forcing and are thus realized by non-equilibrium response, although special cases exist. The reason that non-equilibrium responses dominate the stacking of strata is that it is common for a growing basin-margin depositional system to change its surface area. The size-changing system will easily change the stacking pattern (unsteady stratigraphic configuration) if the external forcing is steady, or, if the steady stratigraphic configuration is maintained, the rate of external forcing must change in a particular pattern (unsteady external forcing). Equilibrium responses can occur, but in very special cases. Conventional sequence stratigraphy should take into account the importance of non-equilibrium response.

Paleogene to Neogene sequence stratigraphy and deepwater depositional systems in Kribi-Campo/Rio-Muni margin (Offshore Cameroon-Equatorial Guinea Margin)

2D seismic data and Gamma Ray logs were interpreted to document the Tertiary deepwater depositional system observed in the southern part of the Kribi-Campo sub-basin and the northern part of the Rio Muni basin, both basins separated by the Campo high. The sedimentary filling of both basins occurred with cyclicity during the Tertiary. The Paleogene filling exhibits at least three Seismic Unit Packages (SUP1 to SUP3) interpreted as some Feeder Channels-Lobe Complexes (FCLC). The units with Mass Transport Complexes (MTCs) are low amplitude and chaotic to transparent seismic facies. They are interpreted as mud-rich complexes. The units related to FCLC, features high to moderate amplitude with shingled oblique progradational clinoforms. The Neogene filling is dominated by some submarine Leveed-Channels Complexes associated to Lobes (LCCL) with low to moderate amplitude and concave-up mounded configuration. The well log analysis revealed three main electrofacies namely, shale, siltstone, and sandstone that were deposited in various depositional environments. Shale lithology are underlined by irregular, bell and bow gamma ray log motifs which may be deposited in inner shelf, tidal channels and channel-levees systems that are associated with transgressive to regressive depositional sequences. Sandstone and siltstone lithology are typified by funnel and cylindrical gamma ray log motifs that are deposited in prograding marine shelf fans and slope channels. Influenced by the high slope of paleotopography around the Campo High, the submarine channel-levee are confined to a western part of Kribi-Campo sub-basin. The FCLC shows large planar distribution, while the MTC are poorly structured.

Study on sequence stratigraphy in the Permian sediments of terrestrial sequences within the Chintalapudi sub-basin, Godavari Coalfield, Southern India: insight from palynology and geochemistry

Study on sequence stratigraphy in the Permian sediments of terrestrial sequences within the Chintalapudi sub-basin, Godavari Coalfield, Southern India: insight from palynology and geochemistry

Depositional Facies and Sequence Stratigraphy of Kodiak Butte, Western Delta of Jezero Crater, Mars

AbstractHigh‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control.

Reservoir Prediction and Prospectivity of Omos Field Onshore Niger Delta Basin, Nigeria

Reservoir prediction and prospectivity are performance indices of the oil and gas field development planning and reserves estimation which depicts the behaviour of the reservoir in the future; its success is dependent on accurate description of the reservoir rock properties, fluid properties, rock-fluid properties and flow. Hence, the objective of this paper was to investigate and predict the reservoir and prospectivity of Omos Field, Onshore Niger Delta Basin, by integrating appropriate standard methods. Results obtained from rock physics attribute map analysis revealed very high Mu-Rho values between 13.0-16.2 Gpa, that is expected for sand presence, and this agrees with the good quality reservoir sands predicted from sequence stratigraphy study.Lambda-Rho values obtained ranges between - 1 to 9.5 GPa, with a much lower value between -1 to 4.3 in the prospective zone that indicates the presence of hydrocarbon bearing sand. These results agree with the results of structural and amplitude maps analysis. Hence the prospective reservoir has a very good hydrocarbon potential in this zone and should be a target for further appraisal for development and production purposes.

3D static modeling and sequence stratigraphy using well logs and seismic data: An example of Abu Roash G member in Bahga oilfield

This research uses both three-dimensional (3D) modeling and geologic well control to piece back together the architectural parts of the Late Cretaceous formations. The goal is to figure out the sizes, directions, locations, and controls of the layers of the fluvial sandstone reservoirs. Sequence stratigraphy is essential for 3D reservoir modeling and petroleum geology understanding in the Bahga oilfield. The purpose of this work is to create a static model that shows the layers and facies distribution in the reservoir interval. We will use data from nine well logs and 22 seismic lines calibrated by the Abu Roash G Member reservoir core intervals to accomplish this. The petrophysical study discovered three parts in the Abu Roash G Member reservoir rock: channel fill that is affected by tides, channel fill that is dominated by tides (intertidal sands), and channel top with lenticular bedded sandstone. The model's findings point to the existence of an NNW-oriented sand body, which could be a prime location to produce hydrocarbons. The original oil in place (OOIP) is about 3,438,279 Stock Tank Barrels (STB), and the oil reserve reaches up to 1,031,484 (STB). Sequence stratigraphic analysis using seismic and well log information (SB) reveals that the Upper Cretaceous AR/G reservoir of the Bahga field is characterized by third- and fourth-order stratigraphic sequences, which are constrained by three Maximum Flooding Surfaces (MFS) and two Sequence Boundaries. The integration of the derived geological model and sequence stratigraphic results can lower future extraction risk by identifying the locations and trends of the geologic facies with the necessary petrophysical properties for the hydrocarbon accumulations.

Paleoclimate changes across the Cenomanian–Santonian transition at the southern Neo-Tethys margin (SW Iran): An integrated approach

The Cenomanian–Santonian (C–S) carbonate successions include valuable petroleum reservoirs in the Zagros Basin. They also provide important information on the paleogeographic setting, paleoclimatic conditions, and tectonic evolution of the southern Neo-Tethys margin. This study focuses on the paleoclimatic changes across the C–S transition using the petrographical, petrophysical, paleontological, major and trace element and isotope geochemical data from three subsurface sections selected from the southern Dezful Embayment and northwestern part of the Persian Gulf. Remarkable differences in allochemical (skeletal and non-skeletal) elements indicate dissimilar paleoclimatic conditions during the Cenomanian–Turonian and Santonian. Paleoexposure events are related to diagenetic processes such as extensive meteoric dissolution (karstification) and the development of bauxitic–lateritic paleosols with high Fe, Al, and kaolinite concentrations indicating warm and humid (tropical) conditions. Increased values of Fe, Al, Rb, and 87Sr/86Sr isotopic ratios and depletion of Ca, Sr, δ18O, and δ13C considered together indicate meteoric diagenetic effects under this paleoclimatic condition. Spectral gamma measurements are used to investigate paleoclimatic conditions. Low content of Uranium (U) throughout the transgressive systems tract (TST) and high concentration in the regressive systems tract (RST) along with low contents of kaolinite within the Santonian sequence denote the predominance of arid conditions. The major fall in U concentrations at the Cenomanian–Turonian interface (CT-Exposure Surface) could be regarded as an outcome of the fall in the relative sea-level and a proxy of oxidizing conditions (Th/U > 7) that could be the consequence of a change in paleoclimate from humid/semi-humid to humid. Evidence for a 3–4 °C decrease in paleo-temperature and increase in aridity are recorded during the Cenomanian–Santonian transition in the Zagros Basin, which is in close agreement with global trends. This cooling pattern is attributed to a decline in atmospheric CO2 levels and alterations in oceanic circulation, specifically an increase in meridional circulation.

Distribution, taxonomic diversity and ecology of paleogene <i>Bacillariophyta</i> in Ukraine

The geographic distribution, level of taxonomic diversity, and ecological preferences of Bacillariophyta complexes extracted from Paleogene deposits in various regions of Ukraine are characterized. The stratigraphic sequence of diatom assemblages, the relationship of the conditions of their formation to paleoceanological events in sedimentation basins, and the biostratigraphic significance are traced. The most taxonomically diverse (up to 250 species) associations of marine diatoms and silicoflagellates are found in the Middle to Upper Eocene deposits of the northeast margin of the Dnieper-Donetsk Depression, the northwest margins of the Donbas, and the slopes of the Voronezh Uplift. In Eocene-Oligocene deposits of the Ukrainian Shield, diatom complexes consist of over 60 marine and brackish taxa. Early Oligocene marine associations, widespread in the Sambir Carpathians and the eastern part of the Azov region, include over 130 species-level taxa. Changes in the proportion of ecological groups of diatom algae indicate their formation under different facies conditions and the transition from marine warm to more cold-water coastal-marine environments during the Eocene, with episodes of freshwater input in the Oligocene.

A multi-proxy geochemical and micromorphological study of the use of space and stratigraphy of a Viking-age house in Ribe, Denmark

High-definition approaches are currently revolutionizing our understanding of the archaeology of urban archives. Multi-proxy studies at a high spatial resolution offer especially an opportunity to capture their high data potential. Here we present a study of complex floor layers from an occupation phase dating to c. AD 790–830 uncovered in the Viking-age emporium Ribe, Denmark (c. AD 700–900). In order to better understand stratigraphy and the use of indoor space, mapping for soil geochemistry (portable X-ray fluorescence analysis, pXRF) on a high-resolution grid (0.25 × 0.25 m, n = 1059), was combined with targeted sampling for soil micromorphology and artefact distributions. The results show that the studied occupation phase was composed of several short-lived floor phases belonging to two consecutive houses that had been sampled in conjunction, and which exhibited a complex stratigraphy. The older house phase had a primarily domestic function, where ten functional areas could be defined, and are interpreted as designated spaces for food preparation, storage, sitting or sleeping, and weaving. A younger house phase contained a metal workshop in addition to domestic functions. Methodologically, a number of new, potentially anthropogenic, elements of archaeological interest, such as arsenic, manganese and sulfur, were identified that may contribute to interpretations, while the multi-proxy approach elucidates the refined scale at which we can understand a complex stratigraphic sequence and the integrity of its units. This study shows how the various aspects of Viking-age urban life (craft production, domestic life) were integrated, and sheds light on the dynamics of urban occupation.

Seismic attributes and instantaneous spectral analysis-based temperature-porosity simulations: An example of imaging shale gas-bearing basin floor fans of early-cCretaceous delta sequences, Southeast Asian Basin

Basin floor fans (BFF) of deltaic depositional systems are important stratigraphic traps, which are sourced by the regionally developed meandering channel belts and associated deposits of point bar facies. The vertical and lateral changes in the tectonics and sea level adversely affect the temperature (θ) and porosity constraints of petroleum plays within BFF of the lowstand system tracts. These fluctuations impact the sedimentary controls on thickness, lithology-impedance contrast, phase, and frequency of BFF. As a result of the reliance on full-spectrum seismics, quantifying thin-bedded stratigraphic wet gas-bearing intervals (WGI) and light oil-bearing intervals of petroleum systems becomes extremely difficult. This study utilizes seismic attributes and instantaneous spectral analysis-based temperature-porosity reservoir simulations (TPRS) to quantify the BFF of the Early-Cretaceous delta of the Miano gas field, Central Pakistan. The 47-Hz peak-tuned frequency component of spectral decomposition [SpecDecomp] images a 154 km2 NEE-SWW traversed and regionally developed stratigraphic prospect. Linear regression of R2 > 0.80 between spectral decomposition-based tuning frequency of 47-Hz and gross reservoir thickness of BFF validates the presence of gas-bearing shales. The 47-Hz wavelet-based TPRS has resolved the phase reversals and seismic-doublet signatures for thin-bedded shale PETROS at θ of 170°F to 200°F and porosities of 22 % to 32 % of WGI within BFF. TPRS at 47-Hz SpecDecomp profile between the frequency bandwidth spectrums of 12–62-Hz has reappraised the exact morphology of the continental shelf, shelf-slope, and BFF. A 21 m thick aggradational parasequence of BFF was deposited at an angle of 2° during the onset of subsidence and rapid fall, followed by a subsequent standstill of sea-level at θ of 170 to 200°F, ∼26 to 35 % porosities, and laterally fractured subsidized regimes of WGI.. A 20 m thick retrogradational fluvial-dominated facies was deposited at an angle of 35° during a rising followed by a standstill of sea level at a θ of 140 to 165°F, ∼08 % to 18 % porosity, and poorly fractured uplifted compressional regimes of light oil-bearing intervals. The aggradational WGI of Lowstand System Tracts was completely embedded by retrogradational shales of transgressed system tracts from the top of the aggradational and laterally. The uncertainty analysis has prevailed with a moderate-to-good R2 > 0.75 for BFF and a very poor R2 < 0.1 for fluvial-dominated point bar traps. Our workflow has implications in terms of exploring the tectonics and stratigraphic frameworks within the petroleum systems for imaging the most productive zones in a single snapshot of 47-Hz tuning frequency.

Facies and geochemical characteristics of the Middle-Lower Ordovician Yingshan Formation in the Tarim Basin, NW China: Implications for the high-frequency sequence stratigraphy in shallow-water carbonate platform

Shallow-water carbonates from the Yingshan Formation are important target of hydrocarbon exploration in Tarim Basin. Detailed descriptions of outcrop, core, and thin sections, isotopic composition analysis, and trace element analysis were conducted. Seven lithofacies which consists of two facies belt groups were identified and used to interpret deposition environments of Yingshan Formation: (1) peritidal carbonate, with relatively lower δ13C values from −4.2% to −1.9%, mainly represented by intertidal to supratidal facies and restricted subtidal facies and (2) open-marine subtidal carbonate, with higher δ13C values (−1.5% to −0.3%), mainly consists of shoal facies and interbank sea facies. On the basis of the lithology sets, four types of meter-scale cycle model (types A–D) were grouped into peritidal sequences and subtidal sequences. On the basis of vertical lithofacies, cycle stacking patterns, and accommodation variations in Fischer plots, two third-order depositional sequences (SQ1–SQ2) were recognized. The sequence boundary between SQ1 and SQ2 is not only a surface of a positive shift of δ13C values, but also the transitional zone of cycle stacking patterns. The sequences can be further divided into four fourth-order sequence sets: Sq1–Sq4. The lower sequences (Sq1–Sq2) are dominated by peritidal facies and characterized by a progressive decreasing in accommodation space probably indicates a longer-term fall in sea level. The upper sequences (Sq3–Sq4) are mainly dominated by subtidal facies and characterized by the accommodation space with a progressive increasement, likely indicates a rising sea level with a longer term. The facies-controlled reservoirs are mainly present in the Sq3, related to the sequence boundary between SQ1 and SQ2.

A germline chimeric KANK1-DMRT1 transcript derived from a complex structural variant is associated with a congenital heart defect segregating across five generations.

Structural variants (SVs) pose a challenge to detect and interpret, but their study provides novel biological insights and molecular diagnosis underlying rare diseases. The aim of this study was to resolve a 9p24 rearrangement segregating in a family through five generations with a congenital heart defect (congenital pulmonary and aortic valvular stenosis and pulmonary artery stenosis), by applying a combined genomic analysis. The analysis involved multiple techniques, including karyotype, chromosomal microarray analysis (CMA), FISH, genome sequencing (GS), RNA-seq, and optical genome mapping (OGM). A complex 9p24 SV was hinted at by CMA results, showing three interspersed duplicated segments. Combined GS and OGM analyses revealed that the 9p24 duplications constitute a complex SV, on which a set of breakpoints matches the boundaries of the CMA duplicated sequences. The proposed structure for this complex rearrangement implies three duplications associated with an inversion of ~ 2Mb region on chromosome 9 and a SINE element insertion at the more distal breakpoint. Interestingly, this genomic structure of rearrangement forms a chimeric transcript of the KANK1/DMRT1 loci, which was confirmed by both RNA-seq and Sanger sequencing on blood samples from 9p24 rearrangement carriers. Altogether with breakpoint amplification and FISH analysis, this combined approach allowed a deep characterization of this complex rearrangement. Although the genotype-phenotype correlation remains elusive from the molecular mechanism point of view, this study identified a large genomic rearrangement at 9p24 segregating with a familial congenital heart defect, revealing a genetic biomarker that was successfully applied for embryo selection, changing the reproductive perspective of affected individuals.

Sedimentological evolution of the Quibas site: High-resolution glacial/interglacial dynamics in a terrestrial pre-Jaramillo to post-Jaramillo sequence from southern Iberian Peninsula

The sedimentary infill of the Quibas karstic site (Early Pleistocene, southern Spain) represents the only continuous succession with remains of continental vertebrates in Europe from pre-Jaramillo to post-Jaramillo age. The Quibas site, with a significant paleontological record, is dated between 1.1 and 0.9 Ma and offers a unique opportunity to carry out a paleoclimatic reconstruction of the time period immediately after the arrival of the first humans to western Europe. For this reason, defining the dominant sedimentary processes in the different stratigraphic units and the associated paleoenvironment is essential. The Quibas site is made up of two karstic features with two stratigraphic sequences: Quibas-Cueva, containing six lithostratigraphic units, and Quibas-Sima, which contains seven lithostratigraphic units. The detailed description and analyses of the stratigraphic sections have allowed the characterization of various autochthonous and allochthonous facies of cave deposits. Paleoclimatic proxies, inferred from sedimentological analyses, reveal a record of several alternating humid and arid phases resulting from the Early Pleistocene glacial-interglacial cycles, allowing correlation to the marine oxygen isotope record. The lowermost units (pre-Jaramillo) were deposited during a long-lasting interglacial, correlated to MIS 33–31. It was followed by an increase in aridity in the intermediate units of Quibas-Sima and uppermost unit of Quibas-Cueva (Jaramillo), revealing the beginning of a glacial period at the start of the Jaramillo subchron (1 Ma), which can be correlated to MIS 30. The upper Jaramillo and post-Jaramillo units suggest these were deposited in alternating periods of aridity and humid conditions, although less humid than the pre-Jaramillo period, probably representing the MIS 29 interglacial, the MIS 28 glacial and the MIS 27 interglacial.

Predicting natural arsenic enrichment in peat-bearing, alluvial and coastal depositional systems: A generalized model based on sequence stratigraphy

Hazardously high concentrations of arsenic exceeding the threshold limits for soils and drinking waters have been widely reported from Quaternary sedimentary successions and shallow aquifers of alluvial and coastal lowlands worldwide, raising public health concerns due to potential human exposure to arsenic. A combined sedimentological and geochemical analysis of subsurface deposits, 2.5–50 m deep, from the SE Po Plain (Italy) documents a systematic tendency for naturally-occurring arsenic to accumulate in peat-rich layers, with concentrations invariably greater than maximum permissible levels.A total of 366 bulk sediment samples from 40 cores that penetrated peat-bearing deposits were analysed by X-ray fluorescence. Arsenic concentrations associated with 7 peat-free lithofacies associations (fluvial-channel, levee/crevasse, floodplain, swamp, lagoon/bay, beach-barrier, and offshore/prodelta) exhibit background values invariably below threshold levels (<20 mg/kg). In contrast, total arsenic contents from peaty clay and peat showed 2–6 times larger As accumulation. A total of 204 near-surface (0–2.5 m) samples from modern alluvial and coastal depositional environments exhibit the same trends as their deeper counterparts, total arsenic peaking at peat horizons above the threshold values for contaminated soils.The arsenic-bearing, peat-rich Quaternary successions of the Po Plain accumulated under persisting reducing conditions in wetlands of backstepping estuarine and prograding deltaic depositional environments during the Early-Middle Holocene sea-level rise and subsequent stillstand. Contamination of the Holocene and underlying Pleistocene aquifer systems likely occurred through the release of As by microbially-mediated reductive dissolution. Using high-resolution sequence-stratigraphic concepts, we document that the Late Pleistocene-Holocene lithofacies architecture dictates the subsurface distribution of As. The “wetland trajectory”, i.e. the path taken by the landward/seaward shift of peat-rich depositional environments during the Holocene, may help predict spatial patterns of natural As distribution, delineating the highest As-hazard zones and providing a realistic view of aquifer contamination even in unknown areas.

The Sequence Stratigraphy and Sedimentary Evolution of the Guantao Formation in the Binxian Uplift Area, Bohai Bay Basin, China

Due to the influence of multiple tectonic movements in rift basins, the sequence and sedimentary filling modes of continental petroleum reservoirs are complex, which makes it difficult to establish isochronous stratigraphic frameworks and thus affects the accuracy of subsequent predictions of effective sand bodies. Taking the Guantao Formation of the Binxian uplift and the surrounding areas as an example, this study established the sequence stratigraphic framework of the Guantao Formation and discussed the controlling effect of sequence stratigraphy on sedimentary filling. According to a combination method of seismic data, well log data, the wavelet transform technique (WTT), and Integrated Prediction Error Filter Analysis (INPEFA) methods, the Guantao Formation in the study area can be divided into 1 long-term cycle (LNG), 4 mid-term cycles (MNG1–MNG4, from bottom to top), and 11 short-term cycles (SNG1–SNG11, from bottom to top). Based on comprehensive analysis of geological and seismic data, three sedimentary facies can be classified: alluvial fan facies, braided fluvial facies, and meandering fluvial facies. The sequence stratigraphic style of the study area has a significant controlling effect on sedimentation and sand body distribution. Different levels of cycles have different impacts on sedimentary facies/microfacies types, the development degree of each sedimentary microfacies, and sand body distribution. The long-term cycle controls the distribution of sedimentary facies, while the mid-term and short-term cycles control the distribution of sedimentary microfacies. The bottom interface of the Guantao Formation (T1) served as the dominant migration channel in the study area, connecting the reservoir and source rocks. When the base-level was in the low stage (MNG1), a large amount of sand bodies developed, forming favorable reservoirs for petroleum. The interlayers at the top of the long- and mid-term cycles served as seal layers to prevent oil and gas from escaping. The MNG1 cycle has a good combination of reservoir and seal, resulting in the accumulation of oil and gas in the MNG1 strata, which became the main oil- and gas-producing layer in the area. These study results can provide effective guidance for future prediction of the distribution of sand bodies and high-quality reservoirs.

ESR/U-series dating of palaeontological remains from the Neanderthal site of Mutzig-Rain (Alsace, France)

The Middle Paleolithic site of Mutzig-Rain, discovered in 1992, has been studied through several pits (called M1 to M15) and excavation area since 2009, evidencing several localities and delivering more than 5000 lithic artifacts and 12,000 well preserved paleontological remains. The main excavation M2 sequence corresponds to a collapsed rock shelter, containing several levels of Middle Paleolithic occupation. The faunal assemblage of the main archaeological levels (l.7a to 7c) from this sequence includes woolly mammoth, reindeer, horse, bison and woolly rhinoceros, reflecting both cold climate and a steppe context for the whole sequence, while microfauna from the lower levels (l.7d and l.10) indicate the occasional presence of forests that could correspond to a cooler climate. In 1995, U-series analyses on bones from M8 were attempted but the obtained results did not follow the sample stratigraphic order. Later, an OSL dating study has placed the M2 archaeological sequence as coeval to the onset of the Weichselian glacial stage (MIS5d-5a), between 100 and 80 ka.The good preservation of the abundant faunal remains at Mutzig-Rain has allowed their use for ESR/U-series dating studies and the results obtained on Mutzig horse teeth are given in the present paper. A first set of analyses of teeth carried out from the M2 excavation provided ages around 106-96 ka for levels M2 l.7, in agreement with the OSL data, despite quite systematic evidence of U-leaching from the dental tissues and the consequent use of the Accelerating Uptake (AU) model for the age calculation. A second set of analyses on teeth from the M2 and M8 localities confirms this uranium leaching trend, placing the deposition of these levels ca 133 -122 ka.Taking the whole set of ESR/U-series ages, which are slightly older than the OSL dates, would suggest that the stratigraphic sequence was deposited between ca 130 ka (M8 l. 6 and M2 l.10) and ca 100 ka (M2 l.7), i.e. on a time range covering the Eemian Interglacial (MIS5e) and the subsequent Early Weichselian Glacial stage (MIS5d-5a). However, as the faunal record indicates a cool climate and an open steppe-like environment for the whole archaeological sequence, the ESR/U-series dating to the Eemian Interglacial in the Mutzig-Rain sequence seems unlikely. In order to check the quality of the paleodosimetric reconstruction of the ESR/U-series analyses, an additional isochron study was performed for the two levels for which several teeth were analyzed: M2 l.7 (n = 4) and M8 l.6 (n = 3). This isochron study validates the proposed reconstruction and confirms the Early Weichselian age of these two levels. These results confirm the chronology established previously with OSL and places Mutzig-Rain as a reference site for the understanding of the Neanderthal Middle Palaeolithic occupation in Eastern France.

Characteristics and Geological Conditions of Coastal Zone Quaternary Sediment Formations in The Binh -Tri -Thien Area under The Context of Global Sea Level Change

Quaternary sediments in the Binh Tri Thien coastal zone are diverse in both material composition and development history. From land to sea, there are 4 structural regions: i) marginal plain region; ii) Coastal lagoon region; iii) Coastal sand dunes region; and iv) Monocline coastal subsidence region. In the vertical direction, all four regions have five sedimentary cycles as follows: a) Early Pleistocene (Q11); b) Early middle Pleistocene (Q12a); c) Late middle Pleistocene (Q12b); d) Early late Pleistocene (Q13a); e) Late late Pleistocene (Q13b-Q2). Four structural zones are characterized by different lithofacies complexes: 1) In the lowstand systems tract (LST) at the beginning of each cycle in all 4 structural zones, the SmaLST facies complex is present; 2) In the transgressive systems tract (TST), there are the following lithofacies complexes: a) region I: MsbTST; b) region II: MlgTST; c) region III: SmTST; d) region IV: Msam,mTST; 3) In the highstand systems tract (HST) there are the following facies complexes: a) Region I: (MsabHST); b) Region II: MslgHST; c) Region III: SmvHST; d) Region IV: SmmHST. The difference in sedimentary facies in the transgressive and highstand systems tract depends on the differentiation of four geological structure regions.&#x0D;

Geochemical study of a Neolithic metallurgical site, Le Planet (France): Detection of paleopollution recorded in archaeological soils

A geochemical study was carried out at the metallurgical site of Le Planet (Fayet, Aveyron), situated in the south of France. The site dates from the 3rd millennium BC, and is one the oldest copper smelting metallurgical sites known in France. The site reveals numerous phases of occupation, all dated from the Late Neolithic. The geochemical study of the site aimed at identifying the signature of the metallurgical activities in the archaeological soils and their spatial distribution. The analyses were carried out by X-ray fluorescence (p-XRF). Two main sampling methods were used. The first, grid-based method, allowed the sampling of the totality of the archaeological excavation surface. The second sampling method aimed to study the vertical distribution of the trace elements in the stratigraphic sequence. Four vertical profiles, positioned throughout the site, allowed a high-resolution sampling of the totality of the stratigraphy, which permitted to identify the stratigraphic distribution of polluted archaeological horizons. The geochemical analyses reveal the importance of the pollution due to the prehistoric metallurgical activities, mainly of lead, copper and arsenic. For instance, the measured values of lead vary between 26 and 9831 ppm. These values for copper are between 53 and 1154 ppm, whereas for arsenic they vary between 35 and 258 ppm. The metallurgical furnaces seem to constitute the main hotspots for the spatial distribution of the pollution. The geochemical study of the profiles identifies two main polluted archaeological horizons, and thus allows having a better understanding of the stratigraphic extension of horizons containing geochemical traces of metallurgical activities.

Sequence stratigraphy of the paleozoic successions in Ghadames Basin, southern Tunisia: Insights from integrated interpretation of well logs and seismic data.

The Ghadames Basin is considered as huge intracratonic structure, which preserved over 4000 m of Paleozoic sedimentary succession deposited over the Precambrian Basement. The present work consists of an integrated interpretation of the Paleozoic interval in the Ghadames basin of southern Tunisia using well logs and calibrated seismic data. Thus, the adopted sequence stratigraphic approach allowed the identification of a total of 3 s-order sequences, bounded by Taconic, Caledonian, and Hercynian unconformities recognized as major tectonic discontinuities in the study area. The determined second-order sequences have been further subdivided into fourteen third-order sequences with their associated systems tracts, which are limited by sequence boundaries (SB), and presenting transgressive surfaces (TS), and maximum flooding surfaces (mfs). Each sequence is characterized by a unique stacking pattern and distinctive facies, thus reflecting the lithology and the corresponding depositional environment. These sequences are composed of claystone and sandstone facies deposited in varying depositional environments, ranging from a shallow marine setting during the Ordovician period to a deep marine environment during the Early Silurian. A complex deltaic environment was evidenced during the Late Silurian involving to a fluvial environment during the Devonian period. The integration of well logs and seismic data proved to be an efficient approach in the delineation of sequence stratigraphy, revealing in detail the spatial distribution and sequence organizations within the study area. These later are controlled by the relative sea level variations, with eustasy is being the dominant factor. The obtained results are mainly correlatable with the sequence stratigraphy of North African basins at a regional scale and Snedden and Lee chart (2010) at a global scale.

Taxonomy and stratigraphic distribution of Lotagnostus (Agnostida: Agnostidae) and associated trilobites and conodonts in the Upper Cambrian (Furongian) of Laurentia.

Two Lotagnostus-dominated faunas from the Windfall Formation at Ninemile Canyon in the Antelope Range of Nevada, USA, are described: an older Lotagnostus nolani Fauna and younger L. rushtoni Fauna. The former is dominated by two morphs of Lotagnostus, one strongly scrobiculate and the other smooth to weakly scrobiculate. Both morphs fall within the broad concept advocated for L. americanus by Peng et al. (2015). The numerous (>1400 sclerites) specimens of Lotaganostus in collections of the L. nolani Fauna confirm that the two morphs do not intergrade and remain distinct throughout ontogeny. Both display multiple traits that distinguish them from the type material of L. americanus, justifying treatment as separate species. Similarly unique, diagnostic features were identified to restore the Asian species L. punctatus and L. asiaticus to full species status, whereas deficiencies in the type material for L. americanus warrant restriction of the name to the holotype. New species described from the Windfall include five agnostoids (Lotagnostus nolani, L. clarki, L. morrisoni, L. rushtoni, and Neoagnostus parki) and one trilobite (Bienvillia eurekensis). Plicatolina nyensis Taylor is reassigned to Mendoparabolina on the form of its pygidium. Conodonts from the Catlin Member of the Windfall Formation and overlying informal Caryocaris shale member of the Goodwin Formation at Ninemile Canyon provide a late Sunwaptan (Eoconodontus Zone) age for the Lotagnostus rushtoni Fauna and assign the entire Caryocaris shale to the early Ordovician Rossodus manitouensis Zone. Combined with published data on trilobite faunas, the conodont faunas confirm strong diachroneity for the top of the Catlin, and a lack of overlap in age between the Caryocaris shale and Bullwhacker Member of the Windfall in ranges to the north and east. Co-occurrence of Lotagnostus nolani and Mendoparabolina nyensis establishes age equivalence of the L. nolani Fauna with the Hedinaspis-Charchaqia (HC) Fauna at the base of the Hales Limestone in the Hot Creek Range, and earlier correlations of the latter with the L. punctatus Zone in Asia are supported. However, isolation of the HC Fauna in starved-basin deposits above a major sequence boundary at the base of the Hales, and ecologic restriction of Lotagnostus to lower slope and basinal environments that prevented association with endemic shallow marine taxa, renders correlation into the biostratigraphy of Laurentian upper slope and platform imprecise on the order of 10s, if not 100s of meters.