Excursion Events Research Articles

Temperature Excursion Management: A Tier-Based Approach for Commercial Oral Solid Dosage Forms

Temperature excursions during product storage, transportation, and handling can deteriorate product quality. Following a temperature excursion event, the impact of the event on the product quality should be evaluated to determine if the product can be used or if it needs to be discarded. Pharmaceutical companies are required to have defined procedures for managing temperature excursions and performing impact assessment after an excursion occurs. In an increasingly complex supply chain, it is vital to develop processes that can expedite the review of these events. A tier-based approach is presented for analyzing the impact of temperature excursion on commercial small molecule drug products intended to be stored at room temperature. Utilization of each of the three tiers is based on whether the excursion temperature and/or excursion duration are within a predetermined, product-specific, allowable range. The stress study temperature defines the allowable temperature range, while the allowable duration is determined using a mathematical approach outlined in this article. Tier 1, specific to the product, allows products to be dispositioned for use without further assessment when temperature excursion events fall within both the product-specific allowable excursion temperature and duration ranges. Tier 2 applies when the excursion temperature is within the allowable range, but the duration exceeds it. Lot-specific release data is used for impact assessment in this tier. Finally, Tier 3 utilizes Arrhenius extrapolation to predict the final degradation and perform the impact assessment when the excursion temperature surpasses the allowable temperature range.Graphical

Aggregator control of battery energy storage in wind power stations to maximize availability of regulation service

Battery energy storage systems can produce very fast bi-directional power flows, which makes them suitable for providing wind power regulation and frequency control services. Though battery systems can provide fast regulation services, their energy storage capacities are quite low in comparison to other generation sources, so regulation responses from them should be optimized to maximize availability of service. This paper proposes an aggregator that optimizes frequency control responses from battery energy storage systems to maximize service availability. The frequency control response from the aggregated system is defined by a single frequency-droop characteristic. This provides the predictability of response required to comply with grid codes and allows the aggregated system to participate in frequency control markets as a single entity. The method of implementation is fail-safe as failure to receive an optimized order from the aggregator does not prevent the battery energy storage systems from responding to frequency events. This mitigates stability concerns relating to communication delays between the aggregator and battery energy storage systems. Battery systems that provide multiple functions, such as frequency control system services and wind power regulation, can participate in the aggregator scheme by assigning a proportion of the battery’s capacity to the aggregator scheme. Simulations performed in DIgSILENT PowerFactory show that the aggregator successfully extends the duration of full regulation service from the battery systems during frequency excursion events.

Magnetic polarity stratigraphy of quaternary sediments from Ramganga paleolake, NW Himalaya, India and its paleoenvironmental implications

Paleomagnetic records from the sediments provide the foundation for studying variations in the geomagnetic field across the geological time sacle. Here, we report a new paleomagnetic data from Quaternary sediments of Ramganga Paleolake, NW Himalaya, India, to provide more insight into the global geomagnetic excursions and paleoenvironmental implications. Paleomagnetic and rock magnetic analyses were performed on a 5 m thick vertical profile of unconsolidated sediments from the Ramganga paleolake (29°46′867″N; 79°14′043″E), located in the Lesser Himalaya at a height of 798 m. One hundred fifty oriented samples from 50 sites (10 cm intervals) were obtained from the vertical section. Extrapolating the optically stimulated luminescence (OSL) dates from literature indicates that the entire section was probably deposited between 38 and 0.8 ka. The rock magnetic data shows that the remanence is carried by a low coercivity mineral and a significant amount of a soft magnetic mineral, most likely magnetite. Virtual Geomagnetic Pole (VGP) latitudes were calculated. Plot of the VGP latitudes against the sample locations from the litho-column allows us for the construction of Magnetic Polarity Stratigraphy (MPS) column. The MPS of the Ramganga paleolake has detected three geomagnetic excursions that are correlated with the global events: the Mono Lake Event (∼28.4-25.8 ka), the Gulf of Mexico Event (∼12.5–17 ka), and the Bagwalipokar Excursion Events (15.5-14.7 ka and 8-2.85 ka) respectively. The lower and middle portion of the paleolake represents the low and high energy depositional environment during the sediment deposition due to wet and arid climatic conditions.

Negative δ13Ccarb excursions within early part of the Lomagundi event recorded in the Paleoproterozoic sedimentary carbonates, Aravalli Supergroup, Rajasthan India: Chemostratigraphy and basin evolution

High resolution stable isotopic (C and O) and geochemical studies of Paleoproterozoic carbonates were carried out in the Umra sub-basin of the Aravalli Supergroup, Rajasthan, India. All the sections, Umra-Dedkiya (UM), Umra-Jampa (BD), and Matoon (MU and GU), have yielded characteristic Lomagundi type positive values, with δ13Ccarb > 4 ‰ VPDB (maximum up to 6.86 ‰). Samples of two sections (UM and BD) have also yielded several distinct negative δ13Ccarb values (up to −6.14 ‰ VPDB). Geochemical validation of trace element and REE data indicate both these types of excursions to be of pristine character, with no signature of organic-remineralisation or hypersaline depositional condition. Mineralogical assemblages lack hypersalinity indicator minerals, such as Na-tourmaline, Na-Albite or scapolite, in the positive δ13C bearing carbonate samples. This supports the inference regarding the observed positive δ13C excursions mimicking the global Paleoproterozoic Lomagundi event. Chemostratigraphic correlation within the basin and with one of the global strato-type Paleoproterozoic carbonate unit from Paso Severino Formation, Uruguay, indicate interruptions in the initial part of the Lomagundi episode marked by several negative δ13C excursion events before achieving a stable positive δ13C character. This phenomenon is also evident from variation in paleoproductivity proxies, such as TOC, TN, Ba and P values, consistent with δ13C fluctuations. Mathematical model calculations have corroborated such a conclusion. All these observations motivated us to present a modified version of the global Paleoproterozoic δ13Ccarb curve and a six stage basin evolution model to explain the evolution of δ13C vis-à-vis variation in atmospheric oxygen.

Building Resilience and Mitigating Impacts of Uncertainties in Technical and Vocational Education and Training in Kenya

Technical and vocational education and training (TVET) has emerged as an avenue through which Kenya aims to fast track her ambition for upper-middle-income economy status, together with the realization of the Big 4 Agenda. However, like other sectors, the TVET sector has shown its vulnerability to sudden and disruptive events manifested by the inability to conduct online training in the wake of the novel Covid-19 pandemic. Such vulnerability has necessitated the need for TVETs to embrace change in training to build resilience in TVET institutions. The Leagile framework has proven to be a stochastic dynamic decision-making tool to handle excursion events in the modern supply chain occasioned by uncertain and turbulent markets. The article adopts a self-completion survey via SMS that targets TVET trainers drawn from TVET institutions in Uasin Gishu County, Kenya. Data is collected using a structured questionnaire administered via SMS. The multiple regressions analysis results confirm that Leagile pedagogy positively and significantly influences resilience building.

Using chemostratigraphy and biostratigraphy methods to define the unconformity underlying the Upper Ordovician Pagoda Formation in the Upper Yangtze Platform

The discovery of hydrocarbon in the Pagoda Formation in South China has received attention from the petroleum industry. This research paper identifies the discontinuity surface underlying the Pagoda Formation. The Upper Ordovician strata were correlated in different regions using the conodont biostratigraphy, and δ13C and δ18O isotope stratigraphy. The biostratigraphic result illustrates that three conodont zones can be established in each study section, and one to three conodont zones are missing in the lower Pagoda Formation and the strata underlying the Pagoda Formation of the Upper Yangtze Platform. Moreover, the chemostratigraphic result highlighted that the development of the lower δ13C isotope positive excursion events in the Xiaogangwan and Liangcun areas was less complete than that in the Jiaodingshan area. Combined with the cyclostratigraphic results, the development of the δ13C isotope positive excursion is not complete. The development of the δ13C excursion event is more complete in the south and east than in the center and north. This demonstrates that the Pagoda Formation began its deposition at different times and the transgression process may have advanced from the southeast to the north and that the contact between the Pagoda Formation and the underlying formation is not conformable. It is proposed that the Late Ordovician in the South China Plate was affected by the tectonic movement and the cooling paleoclimate at that time, which resulted in the discontinuity between the Pagoda Formation and the underlying strata. The unconformity could be the channel for hydrocarbon migration or for the high-quality oil and gas reservoirs being developed and preserved under the unconformity surface.

Biostratigraphy, organic petrography and carbon isotope chemostratigraphy of the Ordovician-Silurian black shales from the Northwestern Domain of Peninsular Malaysia

Integrated biostratigraphy, petrography, organic carbon and carbon isotope chemostratigraphy were used in tandem to assess the paleoenvironment and hydrocarbon potential of the latest Ordovician to Early Silurian basin in the Northwestern Domain of Peninsular Malaysia. Graptolite biostratigraphy indicated a Hirnantian to Aeronian age for the Tanjung Dendang Formation in Pulau Langgun, Langkawi. The graptolite fauna from the Langkawi Islands demonstrates a close association with the South Chinese fauna. The graptolite fragments show a non-granular surface morphology and are mostly present in a long, stipe-like, lath shape when observed under reflected white light microscopy. The pyrites present are relatively small and sparse during the latest Ordovician, suggesting a euxinic condition, but during the Silurian, the pyrites are larger and more common, suggesting anoxic and later dysoxic bottom water. The mean random reflectance of non-granular graptolite in sections perpendicular to the bedding range from 1.8% to 3.07%, and the equivalent vitrinite reflectance ranges from 1.86% Ro to 3.12% Ro, suggesting an overmature stage in term of hydrocarbon generation. The TOC of the Langkawi black shale averages 2.1 wt%, while the rock from the Mahang and Sungai Petani areas measures 1.37 wt% and 0.47% wt%, respectively. δ13Corg chemostratigraphy for the Tanjung Dendang Formation resulted in δ13Corg level between −31.4 ‰ to −28.7 ‰. The Hirnantian Isotope Carbon Excursion (HICE), signalled by a high δ13Corg value, is documented near the base of the formation, followed by a sudden negative shift towards the Ordovician-Silurian boundary. δ13Corg more or less maintained during the Silurian except for slight carbon excursion events during the middle Rhuddanian and early Aeronian. The δ13Corg excursion events from the Tanjung Dendang Formation in Langkawi can be accurately correlated with successions from China, the United Kingdom and Artic Canada.

Predicting the Severity of Runway Excursions from Aviation Safety Reports

Despite all technological advances, runway excursions (REs) remain among the most frequent aviation accidents. Several factors have been shown to contribute to RE incidents. Although different studies have addressed the prediction of REs using quantitative data, the present study contributes to RE research by applying advanced quantitative analysis methods using text mining of voluntarily submitted reports to predict aircraft damage as the outcome of a runway excursion event. The study also intended to unveil relevant predictors from the voluntary safety reports data. The random forest model presented better results than the naïve Bayes and the gradient boosting approaches. The positive predictive value of the random forest method was measured at 74.90%, which is in contrast to 63.58% of the naïve Bayes method and 72.56% of the gradient boosting method. Although several generalizable topics were identified in the reports (such as runway and touchdown zone characteristics, flight control during approach, aircraft malfunction, weather factors, and runway surface and braking action conditions), no defined predictors for runway excursion events resulting in aircraft damage could be established.

Monitoring observations of SMC X-1’s excursions (MOOSE) – II. A new excursion accompanies spin-up acceleration

ABSTRACTSMC X-1 is a high-mass X-ray binary showing superorbital modulation with an unstable period. Previous monitoring shows three excursion events in 1996–1998, 2005–2007, and 2014–2016. The superorbital period drifts from ≳60 to ≲40 d and then evolves back during an excursion. Here, we report a new excursion event of SMC X-1 in 2020–2021, indicating that the superorbital modulation has an unpredictable, chaotic nature. We trace the spin-period evolution and find that the spin-up rate accelerated 1 yr before the onset of this new excursion, which suggests a possible inside-out process connecting the spin-up acceleration and the superorbital excursion. This results in a deviation of the spin-period residual, similar to the behaviour of the first excursion in 1996–1998. In further analysis of the pulse profile evolution, we find that the pulsed fraction shows a long-term evolution and may be connected to the superorbital excursion. These discoveries deepen the mystery of SMC X-1 because they cannot be solely interpreted by the warped-disc model. Upcoming pointed observations and theoretical studies may improve our understanding of the detailed accretion mechanisms taking place.

Magnetostratigraphy of palaeolake sequence from Kumaun Lesser Himalaya, India: Implications on young geomagnetic excursions

Geomagnetic excursions are short‐lived episodes when Earth's magnetic field deviates into an intermediate polarity state. Understanding the origin, frequency, amplitude, duration, and field behaviour associated with excursions is a forefront research area within solid Earth geophysics. Excursion events typically last a few thousand to tens of thousands of years; unlike full reversals, excursions are generally not recorded around the globe. We present here a new palaeomagnetic record (Geomagnetic excursions) from a lacustrine sediment sequence (at times, punctuated by undersized horizons of the gravels) with extraordinarily stable signals. Palaeomagnetic and rock magnetic investigations were performed on a 17‐m‐thick profile of unconsolidated sediments from Bagwalipokar palaeolake (Lat. 29°43′18″; Long. 79°28′42″; altitude 4167 ft), Binta Basin in the Kumaun Lesser Himalaya, situated in the zone of the active North Almora Thrust (NAT). A total of 540 oriented palaeomagnetic samples from 108 horizons (five samples per horizon) were collected from the section. The extrapolation of the optically stimulated luminescence (OSL) date indicates that the whole section was deposited between 45 and 2.5 ka. Magnetic remanence is predominantly carried by magnetite alone. Virtual Geomagnetic Pole (VGP) latitudes were determined using mean declinations and inclinations. Two geomagnetic excursions were observed at younger levels [11.6–10.5 m (15.5–14.7 ka) and 15–11.7 m (8.0–2.85 ka)]. These geomagnetic excursions correlate with the recently reported younger Hawaiian lava flow excursions. The youngest excursion from 8 ka may be attributed to the climatic event beginning at 8.2 ka cooling event of an oxygen isotope record of biogenic carbonate from palaeolake Riwasa in north‐western India that provides a history of the Indian Summer Monsoon (ISM) from ∼11 to 6 ka BP and also the North Atlantic glacial outburst flood and the slowdown of Atlantic meridional overturning circulation. However, further work is needed to verify this interpretation.

Evaluation of Classification Models for Forecasting Critical Voltage Events in Power Systems

The extensive proliferation of renewable energy sources and complex loads stresses the power system operation, making it challenging to ensure the safe and effective operation of networks. In this scenario, forecasting voltage may improve the effectiveness of voltage regulation against critical events. For this reason, this paper explores the effectiveness of machine learning models to predict voltage excursion events in power systems using simple categorical labels. By treating the prediction as a categorical classification task, the workflow is characterized by a low computational and data burden. A proof-of-concept case study on a real portion of the Italian 150 kV sub-transmission network, which hosts a significant amount of wind power generation, demonstrates the general validity of the proposal. A detailed comparison of evaluation metrics offers insight into the strengths and weaknesses of several widely utilized prediction models for this application in the presence of balanced and unbalanced datasets.

Real-Time Event Detection Based on Weibull Distribution Using Synchrophasor Measurements for Enhanced Situational Awareness

The proliferation of Phasor Measurement Units (PMUs) to monitor power grid dynamics at a high resolution (10–100 samples/sec) has opened a new paradigm to situational awareness. Existing event detection techniques for identifying multiple events like transmission line faults, generation trip, line trip, load loss, current transformer (CT) failure, islanding, etc., are prone to misdetection, delayed detection, and false detection. Moreover, most of them can detect events either with fast (transient events) or slow dynamics (oscillatory and excursion events) using synchrophasor measurements. This paper focuses on detecting events with both fast and slow dynamics using wide-area frequency measurements. To this end, a novel method is proposed based on Weibull distribution, which we call as Weibull-based Excursion Transient and Oscillatory (WETO) method. The WETO method can identify the time of inception, location, and severity of the event in near real-time using only a single parameter, known as variability. The events are detected within a time window of 5 cycles using only frequency measurements. The proposed method is validated for the Indian as well as the North American grid disturbances, and the results show that it would be beneficial to the system operator in visualizing the true situation of the grid events.

Carbon, oxygen and strontium isotopic and elemental characteristics of the Cambrian Longwangmiao Formation in South China: Paleoenvironmental significance and implications for carbon isotope excursions

The biosphere experienced episodic perturbations during the Neoproterozoic–early Cambrian, accompanied by major fluctuations of the carbon cycle. However, compared to the Ediacaran–early Cambrian, geochemical records of the Cambrian Toyonian Stage (Longwangmiao), which contains the significant Redlichiid–Olenellid Extinction Carbon Isotope Excursion (ROECE), are scarce. To address this data gap, we conducted measurements of carbon, oxygen and strontium isotopes and element contents of a continuous series of carbonate samples from the Longwangmiao Formation of Well HS2, located in the central Sichuan Basin of South China. Our specific aims were to reconstruct the paleoenvironment and to determine the origin of the ROECE. Strict sample screening was used to ensure that the isotopes and elements were not affected by diagenesis. The 87Sr/86Sr values of Well HS2, and for sites elsewhere, show that sea level gradually decreased during the Cambrian Toyonian Stage. Additionally, the pronounced negative δ13C excursion in the late Toyonian is globally associated with the ROECE, which is widely thought to have resulted from extinctions caused by a transgression. However, a transgression is not shown in the 87Sr/86Sr profile of Well HS2, which we attribute to local karst formation and erosion caused by frequent regional regressions. The interrelationships among several paleoenvironmental proxies show that continental weathering was climatically controlled, which affected the supply of terrigenous detritus, and that the carbonate platform was semi–restricted. Furthermore, profiles of paleoenvironmental proxies indicate that the environment was warm and humid, favoring high biological productivity and diversity during Interval I (early Toyonian), and that it gradually became colder and drier during Interval II (middle Toyonian). We suggest that by the time of Interval III (late Toyonian), the adverse effects of a cold and arid environment were superimposed on the transgression, triggering the ROECE. Our results provide a reference and possible interpretation for other carbon isotope excursion events.

Sedimentary Record of Glacial Impacts and Melt Water Discharge off the East Siberian Continental Margin, Arctic Ocean

AbstractThe East Siberian Continental Margin is a major constituent of the western Arctic Ocean, ideal for studying the evolutionary history of the Siberian Ice Sheet (SIS) based on its unique geographical location and medium‐depth bathymetry. For this study, the sedimentary core CHINARE‐ARC07‐E25 (E25) was analyzed, revealing nearly continuous stable oxygen isotope and mineralogy records that preserved scenarios of the SIS development. Lithostratigraphic evidence suggests that the stratigraphic range of E25 extends to marine isotope stage (MIS) 7. Stable oxygen isotope analysis reveals multiple strong, light‐oxygen isotopic excursions since the penultimate glacial, accompanied by multiple patterns of ice rafted debris content and mineralogy. Based on these isotopic events, the potential factors causing the excursions and the provenance of drainage were evaluated. It was found that the excursion events recorded in pink‐white carbonate detritus layers could be related to the retreat of the Laurentide Ice Sheet. The most typical events, occurring during the deglaciation periods of MIS6/5e and MIS4/3 to early MIS3, were characterized by involving a mixture of two or more sources, and could be used to trace the activity of the SIS, which has been ignored in previous studies. Findings of this study are expected to advance the understanding of SIS contribution to the western Arctic Ocean basin development, which is important for interpreting global climate change behavior of similar ice sheets in the Arctic region.

Evaluating the interaction between engineered materials and aircraft tyres as arresting systems in landing overrun events

According to the registered databases of air accidents around the world, landing overruns are the most probable accidents among all runway excursion events. Although new aircraft are enhanced with the latest technologies that improve the maneuvers safety, the frequency of landing overruns are bound to increase because of the ascending growth rate of annual traffic. The principal scope of this paper is to evaluate the functionality of Engineered Materials Arresting System (EMAS) as a mitigation strategy to reduce the possible consequences of landing overrun events and in particular to determine if installing an EMAS can help land-locked airports to meet Federal Aviation Administration (FAA) recommendations in order to upgrade their Runway End Safety Areas (RESAs). In the previous studies, not enough investigations are dedicated to predicting the behavior of the aircraft and its deceleration rate after interfering EMAS and how different materials as arrestor beds would modify aircraft braking distance in RESA. Therefore, secondary objective of this paper is to determine the most optimum height of EMAS slabs, in function of execution costs and accident severity reduction rate. In this regard, a MATLAB®-based numerical code, which simulate the tire-pavement interface, is developed in order to evaluate the functionality of EMAS for aircraft ground maneuvers. Although this code is developed for both dry and wet runway conditions, dry runway’s surface is selected as the boundary condition of this study. It simulates aircraft arresting distance by calculating a dynamic skid resistance between aircraft main gear and runway pavement with a fix time step. The results are plotted as risk contour intervals on the layout of EMAS that is installed at the RESA. In addition, this numerical code is adopted in order to perform a sensitivity analysis on five arresting bed materials, which consist of three low-density concretes with maximum crushing stress thresholds of 172500, 345000 and 930000 Pa, one gravel-based material and one foam aggregate-based mixture. Among all, low-density concrete with the highest crushing strength causes shorter aircraft arresting distance.

Eye-Blink Parameters Detect On-Road Track-Driving Impairment Following Severe Sleep Deprivation.

Drowsiness leads to 20% of fatal road crashes, while inability to assess drowsiness has hampered drowsiness interventions. This study examined the accuracy of eye-blink parameters for detecting drowsiness related driving impairment in real time. Twelve participants undertook two sessions of 2-hour track-driving in an instrumented vehicle following a normal night's sleep or 32 to 34 hours of extended wake in a randomized crossover design. Eye-blink parameters and lane excursion events were monitored continuously. Sleep deprivation increased the rates of out-of-lane driving events and early drive terminations. Episodes of prolonged eyelid closures, blink duration, the ratio of amplitude to velocity of eyelid closure, and John's Drowsiness Score (JDS, a composite score) were also increased following sleep deprivation. A time-on-task (drive duration) effect was evident for out-of-lane events rate and most eye-blink parameters after sleep deprivation. The JDS demonstrated the strongest association with the odds of out-of-lane events in the same minute, whereas measures of blink duration and prolonged eye closure were stronger indicators of risk for out-of-lane events over longer periods of 5 minutes and 15 minutes, respectively. Eye-blink parameters also achieved moderate accuracies (specificities from 70.12% to 84.15% at a sensitivity of 50%) for detecting out-of-lane events in the same minute, with stronger associations over longer timeframes of 5 minutes to 15 minutes. Eyelid closure parameters are useful tools for monitoring and predicting drowsiness-related driving impairment (out-of-lane events) that could be utilized for monitoring drowsiness and assessing the efficacy of drowsiness interventions. This study is registered with the Australian New Zealand Clinical Trial Registry (ANCTR), http://www.anzctr.org.au/TrialSearch.aspx ACTRN12612000102875. Shekari Soleimanloo S, Wilkinson VE, Cori JM,Westlake J, Stevens B, Downey LA, Shiferaw BA, Rajaratnam SMW, Howard ME. Eye-blink parameters detect on-road track-driving impairment following severe sleep deprivation. J Clin Sleep Med. 2019;15(9):1271-1284.

Anomaly Detection and Segmentation for Wafer Defect Patterns Using Deep Convolutional Encoder–Decoder Neural Network Architectures in Semiconductor Manufacturing

Abnormal defect pattern detection plays a key role in preventing yield loss excursion events for the semiconductor manufacturing. We present a method for detecting and segmenting abnormal wafer map defect patterns using deep convolutional encoder–decoder neural network architectures. Using a defect pattern generation model, we create synthetic wafer maps for 8 basis defect patterns, which are used as training, validation, and test datasets. One of the key capabilities for any anomaly detection system is to detect unseen patterns. We demonstrate that by using only synthetic wafer maps with the basis patterns for network training, the models can detect unseen defect patterns from real wafer maps.

Simulation of Carbon Isotope Excursion Events at the Permian-Triassic Boundary Based on GEOCARB

Abstract The biggest Phanerozoic mass extinctionoccurred at the Permian-Triassic boundary and resulted in the loss of about 95% or more of all marine species. For quite some time, many kinds of abnormal environmental events were adopted to explain the abnormal reduction of carbon isotope at the Permian-Triassic boundary, however there still has not been a unified opinion. In this paper, based on the carbon cycle balance model of the earth under a long-period scale, the contributions of possible cataclysm events at the Permian-Triassic boundary to the carbon isotope records in carbonates were quantitatively simulated. The results proved that a single event, such as volcanism, terrestrial ecosystem collapse or another factor, was not strong enough to lead to the negative bias of carbon isotope at the Permian-Triassic boundary. Even though the release of methane hydrate can result in a comparably large negative excursion of inorganic carbon, this explanation becomes unsuitable when both the shifting Permian-Triassic boundary and the fluctuation record of other inorganic carbon isotopes in the early Triassic as a whole are considered. Therefore, it is suggested that the dynamic equilibrium between inorganic carbon reserves and organic carbon reserves was possibly disturbed by a superimposed effect of multiple events.

Constraining the depositional age of an Upper Cretaceous non-marine and shallow marine siliciclastic succession, Kuji Group, northeastern Japan, based on carbon isotope stratigraphy and U−Pb radiometric dating

Determining detailed geologic ages for pre-Quaternary non-marine and shallow marine siliciclastic successions has generally been difficult due to the rare occurrence of age-diagnostic fossils. In this study, we present the first record of stable carbon isotope stratigraphy derived from detrital woods with U–Pb radiometric dating for felsic tuffs in the Upper Cretaceous Kuji Group, northeast Japan, for which the geologic age has been poorly constrained to date. The radiometric ages for each tuff, obtained by laser ablation–inductively coupled plasma mass spectrometry (LA–ICPMS) analyses, range from 92.6 ± 0.6 to 79.1 ± 1.2 Ma (95% confidence interval). The composite δ13Cwood curve in the Kuji Group is correlated to the Upper Cretaceous reference sections in the Northwest Pacific, North America and Northwest Europe. Based on our correlations, several global carbon isotope excursion events in the late Turonian–early Campanian interval were recognized, and the Upper Cretaceous stage boundaries in the Kuji Group were partially identified, which agree well with previous biostratigraphic assumptions. Further, the depositional age of the dinosaur-bearing bone bed in the Kuji Group was estimated to be restricted to the early–middle Santonian. Our detailed chronostratigraphic framework provides significant implications for sequence stratigraphy, regional tectonic reconstruction and further exploration into the terrestrial ecosystem of the Late Cretaceous East Asian continental margin.

Ash From the Changbaishan Qixiangzhan Eruption: A New Early Holocene Marker Horizon Across East Asia

AbstractPrehistoric Holocene eruptions of Changbaishan volcano in Northeast China are poorly dated, with the exception of the 946 CE Millennium eruption. Poorly refined age estimates for the earlier eruptions present problems for the reconstruction of the eruptive history of the volcano. The Qixiangzhan eruption (QE) is a major controversial event in terms of its eruptive timing (ranging from ~88 to ~4 kyr) and style (effusive or explosive). As a result of the imprecise age estimates for the eruption, a geomagnetic field excursion recorded within the QE comendite has been variably correlated with a number of different excursion events observed elsewhere. In this study, a visible early Holocene tephra was identified in Yuanchi Lake, ~30 km east of the Changbaishan volcanic vent, and was dated to 8831‐8100 cal yr BP using Bayesian age modelling. Glass shard compositions enable the correlation of this tephra with the poorly dated QE, as well as with a tephra (SG14‐1058) recorded in Lake Suigetsu, in central Japan. These correlations confirm that the QE was explosive and that the ash from the QE can serve as an important early Holocene marker bed across East Asia. In addition, we propose an age of ~8100 cal yr BP for the QE based on the precise date of the Suigetsu SG14‐1058 tephra. Our results also confirm that the geomagnetic field excursion recorded in the Qixiangzhan comendite dates to ~8100 cal yr BP.