西安地区部分古遗址考古地磁研究

通过对陕西耀州窑遗址内4个古窑,临潼兵马俑一号坑,西铜一级公路经过黄堡工地开挖的两个五代窑,以及耀州窑博物馆仓库工地内开挖的一个金代窑和一个春秋窑遗址的古地磁研究,初步得出了西安地区古地磁场变化的规律,为鉴定从春秋到金代西安地区的古遗址、古文物提供了考古地磁学上的一个粗略的标准。     

Late glacial and holocene 10Be production rates for western Norway

We present a new regional calibration of the ¹⁰Be production rate from two well‐dated surfaces in southern Norway: a rock avalanche with ¹⁴C‐dated wood and a precisely dated Younger Dryas moraine. Calculated ¹⁰Be production rates are 4.26 ± 0.13 and 4.65 ± 0.14 at g^?1 a^?1 for the Lal/Stone and Lifton scaling models, respectively. Our regional production rate for southern Norway is 5% lower than the canonical global ¹⁰Be production rate with lower uncertainties. Our ¹⁰Be production rate agrees with regional ¹⁰Be production rates from north‐eastern North America and New Zealand. The ¹⁰Be production rate estimate presented here can be used to improve the precision and accuracy of exposure‐dated ice‐marginal features, as well as other surfaces, in northern Europe. Copyright © 2011 John Wiley & Sons, Ltd.     

A high resolution relative paleointensity record from the Gerlache-Boyd paleo-ice stream region, northern Antarctic Peninsula

Herein we document and interpret an absolute chronological dating attempt using geomagnetic paleointensity data from a post-glacial sediment drape on the western Antarctic Peninsula continental shelf. Our results demonstrate that absolute dating can be established in Holocene Antarctic shelf sediments that lack suitable material for radiocarbon dating. Two jumbo piston cores of 10-m length were collected in the Western Bransfield Basin. The cores preserve a strong, stable remanent magnetization and meet the magnetic mineral assemblage criteria recommended for reliable paleointensity analyses. The relative paleomagnetic intensity records were tuned to published absolute and relative paleomagnetic stacks, which yielded a record of the last ∼8500 years for the post-glacial drape. Four tephra layers associated with documented eruptions of nearby Deception Island have been dated at 3.31, 3.73, 4.44, and 6.86 ± 0.07 ka using the geomagnetic paleointensity method. This study establishes the dual role of geomagnetic paleointensity and tephrochronology in marine sediments across both sides of the northern Antarctic Peninsula.     

Holocene and Lateglacial relative sea‐level change in north‐west England: implications for glacial isostatic adjustment models

Relative sea‐level (RSL) change is reconstructed for central Cumbria, UK, based on litho‐ and biostratigraphical analysis from the Lateglacial to the late Holocene. The RSL curve is constrained using ten new radiocarbon‐dated sea‐level index points in addition to published data. The sea‐level curve identifies a clear Lateglacial sea‐level highstand approximately 2.3 m OD at c. 15–17 k cal a BP followed by rapid RSL fall to below ?5 m OD. RSL then rose rapidly during the early Holocene culminating in a mid‐Holocene highstand of approximately 1 m OD at c. 6 k cal a BP followed by gradual fall to the present level. These new data provide an important test for the RSL predictions from glacial isostatic adjustment models, particularly for the Lateglacial where there are very little data from the UK. The new RSL curve shows similar broad‐scale trends in RSL movement predicted by the models. However, the more recent models fail to predict the Lateglacial sea level highstand above present reconstructed by the new data presented here. Future updates to the models are needed to reduce this mismatch. This study highlights the importance for further RSL data to constrain Lateglacial sea level from sites in northern Britain. Copyright © 2012 John Wiley & Sons, Ltd.     

The Ancient Rural Settlement Structure in the Hinterland of Pompeii Inferred from Spatial Analysis and Predictive Modeling of Villae Rusticae

Pompeii, buried by the explosive A.D. 79 eruption of Somma‐Vesuvius, is one of the most studied ancient cities in the Roman world. However, until very recently, the rural settlement in its hinterland had been largely ignored by systematic archaeological research. The ancient landscape around Pompeii consisted of a dense network of Roman farms (villae rusticae). They are believed to have played a vital role in ancient rural life and economy and thus represented the interactive rural–urban relationship in the Sarno River plain. The systematic investigation of published work combined with new fieldwork has yielded a data set of 140 villae rusticae in the Sarno River plain. Geographic information system based spatial statistics as well as predictive modeling were applied to gain a more detailed understanding of the ancient rural settlement structure in relation to the underlying paleoenvironmental and socioeconomic conditions. A high‐resolution pre‐A.D. 79 paleolandscape model of the Sarno River plain was utilized. The aim of this paper is to address theoretical considerations, the methodological implementation, and the archaeological discussion of the analysis of the ancient rural settlements and agriculture around Pompeii.     

Calibration of the in situ cosmogenic 14C production rate in New Zealand's Southern Alps

In situ cosmogenic ¹⁴C (in situ ¹⁴C) analysis from quartz‐bearing rocks is a novel isotopic tool useful for quantifying recent surface exposure histories (up to ～25 ka). It is particularly powerful when combined with longer‐lived cosmogenic isotopes such as ¹⁰Be. Recent advances in the extraction of in situ ¹⁴C from quartz now permit the routine application of this method. However, only a few experiments to calibrate the production rate of in situ ¹⁴C in quartz have been published to date. Here, we present a new in situ ¹⁴C production rate estimate derived from a well‐dated debris flow deposit in the Southern Alps, New Zealand, previously used to calibrate ¹⁰Be production rates. For example, based on a geomagnetic implementation of the Lal/Stone scaling scheme we derive a spallogenic production rate of 11.4 ± 0.9 atoms ¹⁴C (g quartz)^?1 a^?1 and a ¹⁴C/¹⁰Be spallogenic production rate ratio of 3.0 ± 0.2. The results are comparable with production rates from previous calibrations in the northern hemisphere. Copyright © 2012 John Wiley & Sons, Ltd.     

Environmental change in the Ría de Vigo,NW Iberia,since the mid‐Holocene: new palaeoecological and seismic evidence

Pollen analyses (pollen, dinocysts and others) were combined with high‐resolution seismic‐stratigraphy sequences to reconstruct environmental dynamics and regional sea‐level (RSL) changes in a ria in NW Iberia. The chronological framework was established using radiocarbon dating and pollen markers that are related to a number of historical events. Major intensifications of the regional upwelling regime occurred during predominant NAO positive stages, dated to c. 4600–4300, 3800–3600, 3200–2700 and 2600–2400 cal. a BP. The regional Early Highstand System Tract spans from before 4500 to c. 3200 cal. a BP. During this period RSL was still rising, but several short episodes of higher terrestrial influence were detected between c. 4300–3800 and 3600–3200 cal. a BP. A readjustment occurred between 3200 and 2300 cal. a BP, including the first stage of relative sea‐level drop (2.8 ka event) dated to 3200–2800 cal. a BP, with the RSL recovering between 2800 and 2300 cal. a BP. The subsequent Later Highstand System Tract, after 2300 cal. a BP, corresponds to a final period of rising sea level that caused the final inundation of San Simón Bay. Since then, only minor changes in relative sea level can be postulated (e.g. towards the end of the Roman Period, in the Middle Ages and during the Little Ice Age). This new evidence is consistent with most of the available palaeoecological and historical information, but it provides a more detailed, near‐complete succession of simultaneous changes occurring in both the terrestrial and the marine ecosystems.     

Quaternary magnetostratigraphy in Denmark

Magnetostratigraphical results from various historical, Holocene, Lateglacial and Glacial deposits from Central Jutland, Vendsyssel, the Baltic Sea and Schleswig-Holstein are illustrated and discussed. Although only a few archaeomagnetic case studies have yet been made in Denmark, magnetic datings with accuracies of about ±50 years have been obtained on mediaeval kilns by comparing with a dipole transformed modification of the British archaeomagnetic master curve. Furthermore, a study of the expected east–west orientation of some 330 Romanesque churches in Denmark seem to indicate that about 25% of these churches were magnetically orientated; thus some kind of a magnetic compass may have been in common use in the twelfth century in Denmark. Radiocarbon-dated Holocene lake sediments from lake Skanderborg reveal a distinct pattern of magnetic secular variation with fairly short time constants, which may be useful in magnetostratigraphical correlations of other lake sediments. Also Lateglacial and Early Postglacial sediments from the southern Baltic Sea show systematical magnetic patterns, whereas glacial boulder clay at the bottom shows disturbed directions, obviously moulded by the moving ice. Lateglacial Younger Yoldia clay from North Jutland shows well-developed short periodic swings as well as an extreme declination variation of some 80° to 90°, the so-called 'Nørre Lyngby declination excursion' around 14,000 B.P. A sequence of Older Yoldia clay at the same site furthermore shows significantly low inclination values, the so-called 'Rubjerg low inclination excursion' of an age between 23,000 B.P. and 40,000 B.P. Finally, a well-clustering palaeomagnetic direction from a Weichselian glacial boulder clay from Timmerhorn north of Hamburg is discussed from a hierarchical, statistical point of view.     

The Hilina Pali palaeomagnetic excursion and possible self‐reversal in the loess from western Ukraine

A loess‐palaeosol succession from the last glacial cycle was palaeomagnetically studied in the Rivne abandoned brickyard (western Ukraine). Two samples of undisturbed loess from the same depth of parallel sections display steep negative inclinations. These reversed directions in the loess dated at c. 18 ka may possibly be correlated with the Hilina Pali palaeomagnetic excursion. This is the first occurrence of the Hilina Pali in a loess sediment. Unfortunately, the loess with negative inclination does not form any continuous layer that could be suitable for studies of detailed features of geomagnetic field inversion. Another six samples from an illuvial horizon of the Holocene soil also showed negative inclinations and strongly deviated declinations. This part of the section does not represent, however, any palaeomagnetic excursion. The anomalous magnetization in maghemite‐ and titanomagnetite‐rich sediment results most probably from self‐reversal remagnetization. A new insight into palaeomagnetic excursions noted in loess, especially in its parts affected by pedogenic processes, is recommended.     

Were last glacial climate events simultaneous between Greenland and France? A quantitative comparison using non‐tuned chronologies

Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard–Oeschger events are assumed to have been synchronous over wide areas, and then used as tie‐points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard–Oeschger‐type events in a well‐dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well‐dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi‐centennial time scales. If possible, comparisons between proxy archives should be based on independent, non‐tuned time‐scales. Copyright © 2009 John Wiley & Sons, Ltd.     

Integrated geothermal modeling on different scales in the Northeast German basin

Geothermal modeling is an important part of large-scale basin studies. Based on a new 3D structural model of the Northeast German basin, the present day regional geothermal field is modeled. Range and regional trend of the modeled temperature values are in agreement with the published data. Due to the high spatial resolution, the calculated temperature distribution provides additional information with respect to areas where no measured data is available. The results are used as input and boundary parameters for small-scale models of geothermal energy production. In general, in many regions not enough data is available to define all necessary physical or chemical parameters for modeling. In this context, data obtained from the large-scale model help to constrain unknown parameters. Subsequently, the small-scale model is used to simulate various production schemes focusing on enhanced predictions with respect to the possible lifetime of such installations. The simulation results also show the need for elaborated models if reliable predictions of the temperature evolution are required.     

Micro‐PIXE Geochemical Fingerprinting of Nephrite Neolithic Artifacts from Southwest Bulgaria

Neolithic artifacts made of nephrite, □Ca₂(Fe,Mg)₅Si₈O₂₂(OH)_2, are found at prehistoric settlements in Bulgaria. This study investigates these objects based on particle induced X‐ray emission using a scanning nuclear microprobe (micro‐PIXE technique). Seven nephrite artifacts from the Neolithic sites of Kovachevo, Bulgarchevo and Galabnik in southwest Bulgaria were analyzed to quantify their composition and to establish if a correlation exists between the distribution of major and trace elements, color, impurities, and texture. The nephrite artifacts are tremolite in composition, with a proposed ultrabasic origin. Based on the geochemical data obtained by micro‐PIXE, we divide the artifacts into Group 1 objects from the Kovachevo site and Group 2 objects from the Galabnik and Bulgarchevo sites. The analytical data and microprobe analyses are compared with geochemical data of nephrite from across the globe. The results are in a good agreement with previous electron microprobe and electron paramagnetic resonance (EPR) spectroscopy data. Our study provides a better understanding of the mineralogy and geochemistry of nephrite artifacts and helps to address questions regarding origin and the distribution of such materials in Bulgaria and other Balkan countries.     

Relative Sea‐Level Changes During Roman Times in the Northwest Mediterranean: The 1st Century A.D. Fish Tank of Forum Julii,Fréjus,France

Fish tanks become fashionable throughout the Mediterranean area between the 1st century B.C. and the 1st century A.D. Because of this narrow chronological window, and their link to former sea level, they constitute precious archives to investigate relative sea level (RSL) since the Roman period, especially when combined with fossilized marine benthos found attached to the fish tank walls. Here, we present new results from an integrated analysis of a fish tank located in the Roman colony of Fréjus, Southeastern France. The well‐preserved biological remains on the fish tank wall allow us to estimate an RSL rise of 40 ± 10 cm at Fréjus since Roman times, consistent with a recently published range of −32 to −58 ± 5 cm for the Northwestern Mediterranean for the same time. By contrast, the findings contradict the ∼150 cm of RSL change since Roman times reported for the Northwestern Mediterranean by some authors. © 2013 Wiley Periodicals, Inc.     

The Lastglacial and Holocene seismostratigraphy and sediment distribution of Lake Bolshoye Shchuchye,Polar Ural Mountains,Arctic Russia

Seismostratigraphical studies of the 11.8‐km²‐large and ~140‐m‐deep Lake Bolshoye Shchuchye, Polar Ural Mountains, reveal up to 160‐m‐thick acoustically laminated sediments in the lake basin. Using a dense grid of seismic lines, the spatial and temporal distributions of the sedimentary history have been reconstructed. Three regional seismic horizons have been identified and correlated with the well‐dated 24‐m‐long sediment core retrieved from the lake. Isopach maps constructed from the seismic data show four phases of sedimentation. A contour map of the deepest regional seismic reflector represents the earliest hemipelagic sedimentation in the lake. Three contour maps represent time intervals covering the last 23 cal. ka based on the well‐dated core stratigraphy from the lake. The detailed time constraints on the upper stratigraphical units in the lake allow calculation of the lake's development in terms of sediment fluxes and the denudation rates from the Last Glacial Maximum (LGM) to the present. The sedimentation in Lake Bolshoye Shchuchye has been dominated by hemipelagic processes during at least the last 24 cal. ka BP only locally interrupted by delta progradation and slope processes. A major shift in the sediment accumulation at c. 18.7 cal. ka BP is interpreted to mark the end of the local glacial maximum, greatly reduced denudation and the onset of the deglaciation period; this also demonstrates how fast the glaciers melted and possibly disappeared at the end of the LGM. The denudation rate during the Holocene is only a fifth of the LGM rate. The age of the oldest stratified sediments in Lake Bolshoye Shchuchye is not well constrained, but estimated as c. 50–60 ka.     

中国区域化探若干基本问题研究：1999—2009

1999—2009年,中国区域化探发生了根本性改变。主导思想是以地球化学理论为指导研究区域化探方法技术问题和进行矿产资源潜力评价。区域化探方法技术研究的基本要求是最大限度保持原生地球化学分布特征,表生地球化学条件下采样物质问题是区域化探方法研究的核心,样品采集应以代表地质找矿信息的基岩物质成分为原则,在全国范围内最大限度地保持采样物质的一致性。基于成矿地球化学理论建立资源潜力地球化学评价方法和实行地质找矿定量预测,使勘查地球化学从单纯方法手段上升到指导地质找矿的理论高度。主要标志是在全国建立完整的区域化探工作方法技术系统和实行样品分析质量全程监控。在区域化探高精度数据基础上绘制与出版精美的地球化学图集,使区域地球化学图精确地反映地质背景分布与异常特征,促进区域化探数据信息深度开发和利用,建立具有从区域、普查到详查进行全过程独立开展资源调查、评价和预测的方法技术体系和工作程序。区域化探长期支撑中国地质找矿工作,是整个地质找矿工作的先导。随着新一代地区和全国地球化学图的形成,将在基础地质和成矿规律研究以及揭示重大地质事件等方面提供新的发现、新的认识和新的观点,对于未来中国勘查地球化学和整个地质工作产生重要影响。     

Holocene environmental change in the West African Sahel: sedimentological and mineral‐magnetic analyses of lake sediments from Jikariya Lake,northeastern Nigeria

Previous studies have demonstrated long‐term changes in effective moisture in sub‐Saharan Africa. Here, we reconstruct Holocene environments using a ～7 m lake‐sediment sequence recovered from the northeastern Nigerian Sahel and attempt to distinguish basin‐specific changes from regional climatic variations. The sequence was analysed for sedimentological properties, mineral magnetism and pollen, and dated by ¹³⁷Cs, ²¹⁰Pb excess and ¹⁴C. Extremely arid conditions of the terminal Pleistocene ended ca. 11 500 cal. BP (calendar years) when climate ameliorated and a lake developed until the occurrence of an arid event leading to lake desiccation at ～11 200 cal. BP. Following this, climate ameliorated and a water body re‐emerged. Very wet conditions predominated 11 200–5600 cal. BP, followed by drought between 5600 and 5500 cal. BP and a return to moderate humidity from 5500 to 4000 cal. BP. After 4000 cal. BP, a marked deterioration occurred, culminating in lake desiccation at ca. 800 cal. BP. After this time the climate remained generally dry and the re‐emerging lake was shallow. Comparison of these results with other well‐dated sequences in the region demonstrates the importance of basin‐specific influences on the palaeolimnological records in addition to regional climatic controls. Disentangling these different controls, as well as the reconstruction of Holocene climate, therefore requires a multiple‐basin approach. Copyright © 2008 John Wiley & Sons, Ltd.     

Subsource characterization: Obsidian utilization of subsources of the Coso volcanic field,Coso Junction,California, USA

Six chemical subsource groups were identified in the analysis of 84 obsidian samples collected from subsource locations at Coso volcanic field, California. In prehistoric times, Coso provided obsidian for artifacts found from San Francisco Bay to San Diego to Death Valley to the eastern Mojave Desert. Subsource groups were defined by instrumental neutron activation analysis (INAA) of 29 elements followed by cluster analysis, principal component analysis, and bivariate plotting. The new data are compared to previously published INAA and X‐ray fluorescence data. Characterization of 55 obsidian artifacts from archaeological sites located approximately 100 miles from Coso suggests preferential usage of specific subsources as a function of the directionality of travel. The results are consistent with a bimodal (resident and itinerant) model of procurement. This research illustrates the importance of accurate sourcing of obsidian artifacts when attempting to define subsource usage. © 2004 Wiley Periodicals, Inc.     

Late Quaternary tephrostratigraphy,Ahklun Mountains,SW Alaska

Radiocarbon‐dated sediment cores from six lakes in the Ahklun Mountains, south‐western Alaska, were used to interpolate the ages of late Quaternary tephra beds ranging in age from 25.4 to 0.4 ka. The lakes are located downwind of the Aleutian Arc and Alaska Peninsula volcanoes in the northern Bristol Bay area between 159° and 161°W at around 60°N. Sedimentation‐rate age models for each lake were based on a published spline‐fit procedure that uses Monte Carlo simulation to determine age model uncertainty. In all, 62 ¹⁴C ages were used to construct the six age models, including 23 ages presented here for the first time. The age model from Lone Spruce Pond is based on 18 ages, and is currently the best‐resolved Holocene age model available from the region, with an average 2σ age uncertainty of about ± 109 years over the past 14.5 ka. The sedimentary sequence from Lone Spruce Pond contains seven tephra beds, more than previously found in any other lake in the area. Of the 26 radiocarbon‐dated tephra beds at the six lakes and from a soil pit, seven are correlated between two or more sites based on their ages. The major‐element geochemistry of glass shards from most of these tephra beds supports the age‐based correlations. The remaining tephra beds appear to be present at only one site based on their unique geochemistry or age. The 5.8 ka tephra is similar to the widespread Aniakchak tephra [3.7 ± 0.2 (1σ) ka], but can be distinguished conclusively based on its trace‐element geochemistry. The 3.1 and 0.4 ka tephras have glass major‐ and trace‐element geochemical compositions indistinguishable from prominent Aniakchak tephra, and might represent redeposited beds. Only two tephra beds are found in all lakes: the Aniakchak tephra (3.7 ± 0.2 ka) and Tephra B (6.1 ± 0.3 ka). The tephra beds can be used as chronostratigraphic markers for other sedimentary sequences in the region, including cores from Cascade and Sunday lakes, which were previously undated and were analyzed in this study to correlate with the new regional tephrostratigraphy. Copyright © 2012 John Wiley & Sons, Ltd.     

Surface wave phase velocity maps from multiscale wave field interpolation

Availability of spatially dense broadband observations of seismic surface wave fields allows to derive phase velocity maps on regional scale by non-tomographic means. I present a multiscale interpolation scheme for surface wave fields where for each observed wave field, a multiscale phase velocity map and its standard deviation are calculated from subsets of the available data. Isotropic phase velocity (with an estimate on its standard deviation) is then found as the weighted mean of multiscale maps from different observations. Comparison of different interpolation schemes on synthetic wave fields shows that bivariate linear interpolation of phases in a triangulated region, in conjunction with multiscale stacking, is not inferior than methods involving higher-order polynomials. The recovered phase velocity maps are, in the presence of random uncertainties with realistic magnitude, largely free of artifacts and restore a synthetic input model reasonably well. The method is applied to a subset of Rayleigh wave observations at USArray which yields phase velocity maps well within the range of published results. Multiscale interpolation seems to be a practical alternative to tomographic inversion for regional broadband seismic networks (≥30 stations). It requires no choice of arbitrary parameters and is insensitive to number of earthquakes and their azimuthal distribution.