ESR dating of Pleistocene archaeological localities of the Nihewan Basin,North China – Preliminary results

The well-developed, late Cenozoic Nihewan Beds in northern China are amongst the most famous and well-preserved Quaternary strata in East Asia. The Nihewan Basin is also well-known for its mammalian fossils and stone artifacts, which document early human settlements in high northern latitudes (around 40°N). It is a key geological place to study palaeoenvironments and ancient human activities due to the excellent age-control of the formation by palaeomagnetism. In the present paper, the sediments of two Paleolithic sites were dated using the ESR signals of the titanium center in quartz. In order to check the reliability of our analytical procedures, a reference sample collected near the Brunhes/Matuyama (B/M) boundary at the Donggutuo site was firstly analyzed, yielding an age of 750 ± 88 ka. Then, three samples collected from the Dongpo site were analyzed by the same procedures. Our ESR results indicate that the age of the Dongpo cultural layer ranges between 304 ± 12 ka and 333 ± 23 ka, with an average of approximately 321 ± 15 ka.     

The Feature of Segmentation Activity on the Northern Segment of the Anninghe Fault Zone Since Late Pleistocene

Based on fault geometric features,composite pattern,faulting land-forms and seismic data,this paper discussed the activity behavior along the northern segment of the Anninghe fault(from Xichang to Shimian)since the Late Pleistocene.The fault can be divided into three active segments by discrepancies of their activity:the segment from Xichang to Mianning,the segment from Mianning to Zimakua,and the segment from Zimakua to Tianwan.The southern segment has the background of occurrence of great earthquakes,but the middle and the northern segments can generate strong and moderate events respectively.According to the features of quartz from fault gouges by scanning electron microscopy(SEM),this paper discussed the movement features along the fault and indicated the stick-slipping feature on the segment from Xichang to Zimakua,the creeping feature on the segment from Jiziping to Tianwan and the transitional feature on the segment in between.     

Rock and sediment luminescence dating of an ancient circular stone-walled enclosure at Sønnebøe,northern Scania,Sweden

Dating agricultural artefacts such as field walls and clearance cairns using radiocarbon can be challenging, especially since the association with datable material may be poor. Rock surface burial dating using luminescence offers an alternative. Here we report on the luminescence dating of a medieval circular stone-walled enclosure at Sønnebøe, northern Scania, Sweden, using both buried rocks and sediments. Luminescence burial profiles from IRSL signals measured at 50 °C (IR₅₀) indicated significant prior light exposure in 7 of the 8 samples tested (5 granite, 2 felsic gneiss), in some cases multiple exposure burial cycles were indicated. These rock surfaces had apparently been exposed for sufficient time to allow accurate IRSL ages for the most recent burial event. In contrasts, no useful post-IR IRSL profiles were obtained indicating that this signal was not sufficiently reset to allow accurate determination of the burial dose on any of these rocks. IR₅₀ fading corrections (typically ∼50%) were derived by comparing field saturation with that induced in the laboratory. Quartz extracted from sediments surrounding the rocks gave an average measured to given dose ratio of 1.03 ± 0.01 (n = 90), and these sediment samples were then dated using multigrain aliquots; the corresponding feldspar dose recovery ratio obtained using rock samples was 0.98 ± 0.05 (n = 28). A total of 15 ages were derived; 8 quartz OSL ages from the disturbed coarse grained sediments surrounding the structure, and 7 fading corrected IR₅₀ ages from the surfaces of rocks (2–3 mm chips, ∼1 mm thick) used in the construction of the structure itself. The exposure events preserved by the ring enclosure stones unequivocally show wall building taking place at the site between 800 and 300 years ago.     

Luminescence dating of an Upper Pleistocene alluvial fan and aeolian sandsheet complex: The Senne in the Münsterland Embayment,NW Germany

An up to 15 m thick alluvial fan and aeolian sandsheet complex is exposed in the upper Senne area, on the southern slope of the Teutoburger Wald Mountains (NW Germany). The origin and age of these deposits have been controversially discussed for many years, ranging from Saalian glaciofluvial to periglacial Weichselian deposits. In order to provide a high-resolution chronological framework for the deposits, we conducted luminescence dating of 12 samples from two localities (Oerlinghausen and Augustdorf pits). Both coarse-grain potassium-rich feldspar and quartz minerals were used for luminescence dating. Feldspar was measured using an elevated temperature post-IR infrared stimulated luminescence (IRSL). Quartz was measured using optically stimulated luminescence (OSL) with a conventional single aliquot regenerative dose (SAR) protocol. Feldspar results tend to overestimate quartz ages for the lower part of the sections (alluvial plain and alluvial fan facies) but are consistent with quartz ages for the upper part of the sections (aeolian facies). Quartz ages from both central and minimum age models suggest deposition during the Late Pleistocene Pleniglacial to Late Glacial.     

The impacts of pyroclastic surges on buildings at the eruption of the Soufrière Hills volcano, Montserrat

We investigated the impacts on buildings of three pyroclastic surges that struck three separate villages on 25 June, 21 September and 26 December, 1997, during the course of the andesitic dome building eruption of the Soufrière Hills Volcano, Montserrat, which began on 18 July, 1995. A detailed analysis of the building damage of the 26 December event was used to compare the findings on the flow and behaviour of dilute pyroclastic density currents (PDCs) with the classical reports of PDCs from historical eruptions of similar size. The main characteristics of the PDC, as inferred from the building damage, were the lateral loading and directionality of the current; the impacts corresponded to the dynamic pressure of the PDC, with a relatively slow rate of rise and without the peak overpressure or a shock front associated with explosive blast; and the entrainment of missiles and ground materials which greatly added to the destructiveness of the PDC. The high temperature of the ash, causing the rapid ignition of furniture and other combustibles, was a major cause of damage even where the dynamic pressure was low at the periphery of the current. The vulnerability of buildings lay in the openings, mainly windows, which allowed the current to enter the building envelope, and in the flammable contents, as well as the lack of resistance to the intense heat and dynamic pressure of some types of vernacular building construction, such as wooden chattel houses, rubble masonry walls and galvanised steel-sheet roofs. Marked variability in the level of damage due to dynamic pressure (in a range 1–5 kPa, or more) was evident throughout most of the impact area, except for the zone of total loss, and this was attributable to the effects of topography and sheltering, and projectiles, and probably localised variations in current velocity and density. A marked velocity gradient existed from the outer part to the central axis of the PDC, where buildings and vegetation were razed to the ground. The gradient correlated with the impacts due to lateral loading and heat transfer, as well as the size of the projectiles, whilst the temperature of the ash in the undiluted PDC was probably uniform across the impact area. The main hazard characteristics of the PDCs were very consistent with those described by other authors in the classic eruptions of Pelée (1902), Lamington (1951) and St Helens (1980), despite differences in the eruptive styles and scales. We devised for the first time a building damage scale for dynamic pressure which can be used in research and in future volcanic emergencies for modelling PDCs and making informed judgements on their potential impacts. Editorial responsibility: T. Druitt     

Quantification of the 1998–1999 explosion sequence at Popocatépetl volcano,Mexico

The sequence of large Vulcanian explosions occurring at the andesitic Popocatépetl volcano, Mexico during November 1998 to April 1999 was studied. The size of 26 largest explosions was estimated from broadband seismic records at the distance of 4 km from the crater. The sequence began with the largest explosion (E = 2.6 × 10¹² J) occurring on 25 November at 08:05, and following largest daily explosions were characterized by gradual decrease in the energy. The energy of 20 large (E ≥ 10¹¹ J) explosions was distributed as Student's t-distribution with a geometrical mean Log E = 11.81 (J).     

OSL dating of fine and coarse quartz from a Palaeolithic sequence on the Bistrița Valley (Northeastern Romania)

Previous works focused on optically stimulated luminescence dating of quartz extracted from Romanian and Serbian loess reported significant discrepancies between ages obtained on fine (4–11 μm) and coarse (63–90 μm) quartz. The present study is directed at expanding these investigations. The SAR-OSL and double SAR-OSL protocols are applied on quartz of different grain sizes belonging to 9 samples extracted from a newly identified archaeological site at Bistricioara-Lutărie III on the Bistrița Valley (NE Romania). Radiocarbon ages are also obtained for the 3 uppermost cultural layers hosted in the loess-like deposit.Discrepant ages are obtained between fine (4–11 μm) and coarse (63–90 and 90–200 μm, respectively) quartz for equivalent doses higher than ∼80–100 Gy. However, a very good agreement is achieved for the youngest sample, with an age of ∼8 ka (with a D_e of 38 Gy for fine and 35 Gy for coarse grains, respectively). The comparison with independent control provided by radiocarbon dating suggests better agreement of ages calculated for coarse quartz. Our results are once again proof that concerns should be raised regarding the reliability of the equivalent doses obtained on quartz samples for which the laboratory dose response cannot be fitted by a single saturating exponential function. Further systematic investigations are required regarding the very different saturation characteristics of fine and coarse grained quartz.     

The December 26, 2004, off the west coast of northern Sumatra, Indonesia, M_W=9.0, earthquake and the critical-point-like model of earthquake preparation

Introduction The unexpected December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake, which caused devastating tsunami around the Indian Ocean, reminds seis-mologists of the difficulty of earthquake forecast and/or prediction. For seismologists this earth-quake is almost completely unexpected, because there was neither forecasting (which means the estimation of the future earthquake rate as a function of location, time, and magnitude) nor predic-tion (forecasti…     

The evolution of sub-mesoscale,coherent vortices on the β-plane

Abstract

An investigation is made of the evolution of small-scale, axisymmetric vortices in a stratified fluid with spatially variable Coriolis parameter. The criteria for smadness are a horizontal scale less than or equal to the first internal radius of deformation and a vertical scale less than or equal to that of the ambient stratification. These circumstances match those of Sub-mesoscale, Coherent Vortices frequently observed in the oceans. The dynamical model is the balance equations, which include various effects of finite Rossby number. The principal topics are the regime of nearly uniform propagation, the development of an equilibrium ratio of vertical and horizontal scales (i.e., Burger number selection), and the occurrence of various types of instability for vortices with extremes in amplitude or shape.     

The subterranean electric structure at the Chinese Great Wall Station on Antarctic（CGWSA）

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Changes in the plain river system and its hydrological characteristics under urbanization – case study of Suzhou City,China

ABSTRACT

Rapid urbanization in China has severely disturbed the underlying surface and river systems. The stream structure parameters of Suzhou City were analysed to study the evolution and spatial differentiation of a water system undergoing urbanization. The influencing pattern of different urbanization processes on river system structure and hydrological processes was detected by statistical methods and simulation analysis. The results show that urban sprawl is influenced by both the natural environment and the social economy. At different stages of urbanization, the spatial urban expansion and the natural river characteristics influence the evolution of the river network: during rapid urbanization, the decline in surface water ratio and river density is more intense. The decrease of surface water ratio and river density in rapidly urbanized areas was greatest, followed by that in area urbanized in the 1980s, with few changes in the old town. Under high urbanization, river system indicators tend to stabilize. The rivers’ hydrological features were affected by urbanization, with water yield in the study area increasing from 0.81 to 0.95 m³/m² (1991–2015). The same rainfall intensity results in higher flood levels and greater risk of flooding under rapid urbanization.     

Petrologic composition model of the upper crust in Bohai Bay basin, China, based on Lamé impedances

Seismic attributes, such as P- and S-wave velocity, Poisson’s ratio, and acoustic impedances, all generally can be used for distinguishing different rock types. The non-uniqueness can be largely reduced using Lamé impedances instead of acoustic impedances as additional constraints. We have followed this method to constitute a petrologic composition model of the upper crust in the Bohai Bay basin, China. We briefly review the seismic parameters used for discrimination of rock types and focus our attention on the sensitivity of different combinations of parameters to determine the composition of materials. Corrections for pressure and temperature are performed in order to compare elastic wave velocities and densities measured at room temperature and surface pressure in laboratory with those for representative rock parameters. In a second step, we find the rock classes in the tested area by contrasting known data to laboratory measurements on a variety of rock samples extracted in the area. The basic field data are P-wave velocity values collected along a seismic profile conducted in the Bozhong Depression. The different rock types belonging to a particular rock class are finally constrained by the seismic velocities, Poisson’s ratio, density, acoustic impedance, and Lamé impedance related to the topmost 10 km of the Bohai Bay crust.     

A review of: “The earth: 1 the upper atmosphere,ionosphere and magnetosphere”

Abstract

Edited by Charlotte W. Gordon, V. Canuto and W. Ian Axford, Gordon and Breach Science Publishers, 412 pp., $63.00 ($35.00). (ISBN O 677 16100 X.) 1978.     

The sea level at Port-aux-Français,Kerguelen Island,from 1949 to the present

Relative sea level rise at Kerguelen Island over the last 55 years has been investigated using a combination of historical and recent tide gauge data. The best estimate of relative sea level trend from data sets spanning 38 years is estimated to be 1.1±0.7 mm year^?1. We have tried to quantify the error budget due to some of the possible sources of uncertainty. As expected, the main source of uncertainty comes from oceanic interannual variability, preventing an accurate estimate of sea level trend over short record lengths. However, our values are reasonably consistent with other reported southern hemisphere sea level trends for similar time periods.     

The effect of the Jessica grounding on subtidal invertebrate and plant communities at the Galápagos wreck site

Impacts of the grounding of the oil tanker Jessica off San Cristóbal island, Galápagos, included both effects of oil on biota and also mechanical effects associated with a shallow furrow 50 m x 30 m gouged across the rocky seafloor and wreckage strewn over 7500 m(2). The wreckage represented a minor but potentially chronic source of pollution to the surrounding environment through delayed releases of oil, antifouling compounds and other toxic chemicals, and a possible source of exotic marine taxa. Investigation at the wreck site indicated that impacts on subtidal plant and macro-invertebrate communities were largely confined within 100 m of the wreck site itself. Observed population effects included significant increases in cover of opportunistic algae (filamentous green algae, filamentous red algae and Ulva sp.) and the hydroid Ectopleura media adjacent to the wreck, while densities of the green sea urchin Lytechinus semituberculatus significantly decreased from 0.3 m(-2) adjacent to the wreck to 11 m(-2) at 100 m distance.     

High-resolution optical dating of Late Holocene storm surge deposits – a showcase from Schokland (Noordoostpolder,the Netherlands)

Storm surges have a major impact on land use and human habitation in coastal regions. Our knowledge of this impact can be improved by correlating long-term historical storm records with sedimentary evidence of storm surges, but so far few studies have applied such an approach. Here we apply, for the first time, state-of-the-art optically stimulating luminescence (OSL) methods to obtain high-resolution age information on a sequence of Late Holocene storm surge deposits. By combining this chronological framework of storm surges with other reconstruction methods, we investigate the storm surge impact on the former island Schokland, located in a former inlet of the North Sea (central Netherlands).During the Late Holocene, Schokland transformed from a peat area that gradually inundated (~800 CE) via an island in a marginal marine environment (~1600 CE) to a land-locked island in the reclaimed Province of Flevoland (1942 CE). These transitions are recorded in the sediment archive of the island, consisting of silty clay with sandy intervals deposited during storm surges. A series of ten quartz OSL ages, obtained using best-practice methods to deal with incomplete resetting of the OSL signal and dose rate heterogeneity, reveal two periods of storm surge deposition, around 1600 CE and between 1742 and 1822 CE. Historical sources indicate that major storm surges hit Schokland during these periods. Laboratory analyses (thermogravimetry, grain-size, foraminifera, bivalves and ostracods) corroborates the existence of the two sets of storm surge deposits within the clay sequence. Our study sets a benchmark for obtaining robust depositional age constraints from storm surge sediments, and demonstrates the great potential of modern OSL methods to contribute to improved assessment of storm surge risk. © 2018 John Wiley & Sons, Ltd.     

The effects of adsorptive materials on microbial community composition and PAH degradation at the sediment capewater interface

Capping with layers of inert or adsorptive materials is used to control the release of polycyclic aromatic hydrocarbons(PAH)in sediment but little is known about microbial degradation processes in these materials.A rich native microbial community inhabits the sediment bed,and capping media can influence enrichment and biodegradation activity of benthic microorganisms.The aim of this study was to evaluate the effects of capping media(sand,organoclay,and powdered activated carbon[PAC])on microbial communities under oxic conditions typical of the capewater interface,where naphthalene degradation(model PAH)is likely to be maximized.Bench scale experiments compared naphthalene concentrations,nahAc biomarker abundance,microbial community composition,and cellular attachment in systems amended with adsorptive and non-adsorptive capping materials.Results indicate that activated carbon promoted and enhanced bioactivity;PAC treatments showed high biodegradation rates,nahAc biomarker levels,and attached biological growth consistent with enrichment of the PAHdegrading genus Pseudomonae.In contrast,sand did not enhance biological activity compared to media-free systems.Naphthalene strongly influenced microbial community composition at the species level in all treatments except organoclay,which promoted biological signatures commonly associated with impeding degradation activity.Data overall suggest that adsorptive capping materials can both promote(PAC)and inhibit(organoclay)bioactivity in the surficial layer of caps,indicating that media selection is critical to the design of bioactive capping systems.